JP4385031B2 - Light guide plate and flat illumination device - Google Patents

Description

  According to the present invention, the light guide plate is formed so that the position of the incident end surface portion is minimized, and the gentle first inclined surface portion and the sharp second inclined surface portion whose back surface faces in the opposite direction to the incident end surface portion. When the straight light from the light source travels from the incident end face to the non-incident end face, the taper leak due to the inclination of the wedge-shaped light guide plate itself does not occur and the light is reflected. When the light is reflected at the anti-incident end face portion and proceeds to the incident end face portion, a taper leak occurs at the first inclined surface portion of the back surface portion, or total reflection is performed and proceeds toward the front surface portion. In the second inclined surface portion, the reflection angle of total reflection is small and proceeds at an angle substantially perpendicular to the surface portion, and the cross section provided on the surface portion extends to the convex or concave incident end surface portion and anti-incident end surface portion. The light deflecting section collects the light that has traveled to the surface section, and the surface section The light guide plate can be emitted in a substantially right angle direction, avoiding the reflection of strong light from the light source in the vicinity of the incident end face, and having a light source in the vicinity of the side surface of the light guide plate when the light source is small. The present invention relates to a light guide plate and a flat illumination device that can avoid the occurrence of dark portions at both end portions near the end face portion.

  As a conventional light guide plate and flat illumination device, the light guide plate is formed into a so-called wedge shape, with the thickness decreasing as the distance from the incident end face portion increases in order to maximize the light from the light source. A method is known in which light traveling from the end face to the opposite direction of the incident end face utilizes a taper leak due to the inclination of the light guide plate itself.

  Furthermore, in the case of a large flat illumination device, the thickness of the light guide is reduced as it is farther from the incident end face, and a taper leak of light from the incident end face to the opposite direction of the incident end face is used. There is known a method in which two opposite end faces of the light guide plate are made incident end face portions by using the method of the above.

  In addition, when printing a white light scattering agent on the opposite side of the exit surface of the conventional light guide plate, it is incident even when the printed portion is increased away from the incident end face portion or dots such as irregularities are provided on the light guide plate. The dots were increased as the distance from the end face portion increased.

In addition, as a conventional flat illumination device using a point light source such as an LED, a plurality of LEDs are arranged on the side surface of the light guide plate, and a convex or concave such as a prism is formed on the incident end surface portion of the light guide plate at a position facing these LEDs. There is known a method of providing a shape so that the light beam reaches a part of both corners of the light guide plate.
JP 2003-337333 A JP 2003-029260 A

As the above-described conventional light guide plate and planar illumination device, here, the locus of light rays when light is incident on the wedge-shaped light guide plate 21 will be described with reference to FIGS. 19 and 20.
As shown in FIG. 19, the conventional light guide plate 21 has a wedge shape in which the thickness decreases from the incident end surface portion 31 toward the counter incident end surface portion 41 located on the opposite side of the incident end surface portion 31. Therefore, while the incident light L01 travels to the counter-incident end surface portion 41 located on the opposite side of the incident end surface portion 31, the incident angle of the light beam L01 with respect to the surface portion 61 toward the surface portion 61 is within about 42 ° ( In the case of an acrylic resin), the light is totally reflected by the front surface 61 and proceeds in the direction of the back surface 71 as a light ray L02. However, since the light guide plate 21 has a wedge shape that is thin with respect to the direction in which the light beam travels, the incident angle with respect to the back surface portion 71 is smaller than the critical angle, so the critical angle is broken and the light beam L03 and the light beam L04 are emitted from the back surface portion 71. End up.
Here, for the sake of explanation, the outgoing light that breaks the critical angle is shown only on the back surface portion 71, but the outgoing light that breaks the critical angle similarly exists on the front surface portion 61 as well.

  Thus, as shown in FIGS. 20A and 20B, the thickness of the light guide plate 21 is increased as the distance from the incident end face portion 31 increases in order to make maximum use of light from the light source 9. In the method of using a tapered leak of light that is formed into a so-called wedge shape that is thinned and is directed from the incident end surface portion 31 in the opposite direction to the incident end surface portion 31, when the light source 9 is directional, the vicinity of the incident end surface portion 31 is obtained. Then, the critical angle is immediately broken, that is, high brightness light is emitted by the taper leak. Since this light is emitted light having high brightness and strong directivity, the shape of the semiconductor light emitting element 9 itself is observed (reflected) from the light emitting surface of the entire light source, for example, the light source 9 of the semiconductor light emitting element (LED). There is a problem that will be done.

  Furthermore, in the light guide plate 21 in which the thickness of the light guide plate is reduced as the distance from the incident end face portion 31 increases as described above, the shape of the semiconductor light emitting element 9 itself is not observed from the exit surface. Actually, since the vicinity of the incident end face portion 31 is not used, there is a problem that the light guide plate 21 larger than the necessary area of the flat illumination device must be used.

  Further, in the case of a conventional large flat illumination device, the thickness of the light guide plate 21 is reduced as the distance from the incident end surface portion 31 is decreased, and the light taper from the incident end surface portion 31 in the opposite direction to the incident end surface portion 31 is achieved. In the configuration in which two opposing end surfaces of the light guide plate 21 are made incident end surface portions 31 by using a method utilizing leakage, as shown in FIG. 21, the thickness of the central portion of the light guide plate 21 is the thinnest part, As the weight is reduced, the thickness of the central portion is reduced and there is a problem in mechanical (structural) strength.

  Furthermore, in order to obtain white light by using three color light sources of RGB (red light emission, green light emission, blue light emission) as light sources, when each RGB light source is arranged in an array, each emission color is incident on the end face. It is difficult to mix in the vicinity of the part. For this reason, there is a problem in that each emission color does not become white in the vicinity of the incident end face portion and is emitted in a patchy manner from the emission surface.

  Further, in a conventional illumination device using a light guide plate and a point light source such as one LED at the center of the incident end face, as shown in FIGS. 20 (a) and 20 (b), a semiconductor light emitting device such as an LED is used. Since the light source 9 of the element has directivity, the critical angle is broken while traveling in the direction of the anti-incident end face portion 41 in a narrow range and from the incident end face portion 31 in the direction of the anti-incident end face portion 41. For this reason, there is a problem that both end portions of the incident end surface portion 31 (between the incident end surface portion 31 and the incident light beam L0) become dark portions.

  In addition, in the conventional light guide plate and flat illumination device, the light confined in the light guide plate is simply emitted by a taper leak or a groove or uneven shape provided on the front or back surface of the light guide plate. Are emitted or diffused as they are. For this reason, only light in a state where the luminance and energy of light are low can be emitted. For example, since the light is weak with respect to each pixel of RGB of the liquid crystal display device, the aperture area must be widened. It was an obstacle to miniaturize pixels.

(Object of invention)
The present invention has been made to solve the above-described problems, and provides a light guide plate and a flat illumination device having the following characteristics.

  Light source and light composed of a single semiconductor light emitting element or CCFL, etc., which are monochromatic light or red light, green light and blue light of a plurality of semiconductor light emitting elements, white light using a wavelength conversion material or an array or directivity Crossing the incident end face part that guides the light, the anti-incident end face part that reflects light, the surface part or / and the back part that emits the light, and the front part and the back part. While having a side part, while the straight light incident from the incident end face part does not break the critical angle while traveling to the anti-incident end face part, it is reflected by the anti-incident end face part and proceeds from the anti-incident end face part to the incident end face part In order to break the critical angle, the thickness of the front and back surfaces is minimized at the incident end face, and the thickness of the front and back faces is maximized at the anti-incident end face. The light plate has a back surface facing the anti-incident end surface. A stepwise shape in which a gentle first inclined surface portion and a sharp second inclined surface portion are alternately and continuously connected is formed, and an incident end surface portion and a counter incident end surface portion have a convex or / and concave cross section on the surface portion. A light guide plate provided with a light deflection portion extending in the direction, and a reflector having reflectivity that covers portions other than the incident end face portion and the emission surface of the light guide plate. As a result, when the straight light from the light source travels from the incident end surface portion to the non-incident end surface portion, it is totally reflected on the front surface portion and the back surface portion without causing a taper leak due to the inclination of the wedge-shaped light guide plate itself. The angle at which the light is totally reflected is changed to a larger angle toward the anti-incident end face part, and when reflected at the anti-incident end face part that reflects light and proceeds to the incident end face part, Taper leaks or total reflection causes light close to the critical angle to travel toward the surface. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and the cross section provided on the surface portion has a convex or concave shaped incident end surface portion and anti-incident end surface. The light that has traveled to the surface portion can be condensed by the light deflection portion extending in the direction of the portion, and can be emitted in a direction substantially perpendicular to the surface portion.

  In addition, avoiding the reflection of strong light from the light source in the vicinity of the incident end face, and in the case of providing a light source in the vicinity of the side surface of the light guide plate, dark portions are generated at both ends near the incident end face of the light guide plate when there are few light sources. It can be avoided.

  Furthermore, by providing a light deflecting section having a circular arc shape or a triangular cross section on the front surface portion, the light totally reflected from the back surface portion can be condensed in the direction of the side surface portion. For example, when the light deflection unit has an arc-shaped cross-sectional shape, a sharp light beam is emitted in each direction with respect to each RGB pixel in the LCD, so that the aperture area of the pixel can be reduced. Accordingly, by reducing the size of each pixel of RGB, the amount of pixels per unit area can be made finer, so that a clear image can be provided.

  In addition, the cross-sectional shape of the light deflecting portion provided on the surface portion is maximized at the anti-incident end surface portion, and becomes smaller as it approaches the incident end surface portion. As the area increases, the amount of light that travels in the direction of the anti-incident end face increases even when the light has a spread, so that the amount of light reflected by the anti-incident end face increases, and the amount of emitted light increases, resulting in brighter outgoing light. Obtainable.

  Furthermore, the anti-incident end face part is formed into an arc shape in which the center position of the same distance position swells from the two side face parts, and the second inclined face part is set to the center of the same distance position from the two side face parts. On the other hand, by setting the center to an arc shape close to the direction of the incident end face, the light that has spread from the direction of the incident end face is reflected toward the center by the anti-incident end face and reflected toward the incident end face. When the reflected light is totally reflected by the second inclined surface portion, the diffused reflected light is directed toward the surface portion, and uniform outgoing light can be emitted from the entire surface portion.

  Furthermore, it is possible to eliminate reflection of light sources and luminance spots, and even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not emit immediately in the vicinity of the incident end face part, but once on the opposite side of the incident end face part of the light guide plate. Since the light is reflected and then emitted, the monochromatic light of RGB is mixed in order to proceed while repeating total reflection several times in the light guide plate in the meantime, and complete white light can be obtained. In addition, brightness spots and emission color spots can be controlled along with the brightness, and the light exiting surface of the light guide plate can be made larger. Since the thickness becomes the maximum, it is possible to provide a light guide plate and a flat illumination device having excellent mechanical strength.

A light guide plate according to a first aspect of the present invention is an incident end face part that guides light from a linear light source, an anti-incident end face part that is opposite to the incident end face part, reflects light, and emits the light. It has a surface portion or / and a back surface portion, and a side surface portion that intersects the surface portion and the back surface portion, and does not break the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. In order to break the critical angle while being reflected at the incident end face and traveling from the anti-incident end face to the incident end face, the thickness of the front and back surfaces is minimized at the incident end face, and at the anti-incident end face. A light guide plate having an outer shape that maximizes the thickness of the front surface portion and the back surface portion,
The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion are alternately connected continuously, and the surface portion has a convex shape and / or a concave shape. Are provided with a light deflecting portion extending in the direction of the incident end surface portion and the anti-incident end surface portion, and the second inclined surface portion is centered at the same distance position from the two side surface portions, and the center is an arc shape close to the incident end surface portion direction. The anti-incident end face part has a circular arc shape in which the center position at the same distance from the two side face parts swells .

The light guide plate according to claim 1 is an incident end face part that guides light from the linear light source, an anti-incident end face part that reflects light and is located on the opposite side of the incident end face part, or a surface part that emits the light, or And / or a back surface portion, and a side surface portion that intersects the front surface portion and the back surface portion, and does not break the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. The thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion so that the critical angle is broken while traveling from the anti-incident end surface portion to the incident end surface portion. A light guide plate having an outer shape that maximizes the thickness of the back surface,
The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion are alternately connected continuously, and the surface portion has a convex shape and / or a concave shape. Are provided with a light deflecting portion extending in the direction of the incident end surface portion and the anti-incident end surface portion, and the second inclined surface portion is centered at the same distance position from the two side surface portions, and the center is an arc shape close to the incident end surface portion direction. And the anti-incident end face part has an arc shape in which the center position at the same distance from the two side parts swells, so that when the straight light from the light source travels from the incident end face part to the anti-incident end face part, a wedge shape The light guide plate itself is totally reflected at the front and back surfaces without causing a taper leak due to the inclination of the light guide plate itself. Then, the angle of total reflection at the front surface portion and the back surface portion changes to a larger angle toward the anti-incident end surface portion, and the back surface portion is reflected by the anti-incident end surface portion that reflects light and proceeds to the incident end surface portion. A taper leak occurs at the first inclined surface portion of the light, or total reflection is performed and light close to the critical angle travels toward the surface portion. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.

  Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face.

Furthermore, the light guide plate according to claim 2 is an incident end face part that guides light from a point light source, an anti-incident end face part that reflects light, and a surface part that emits light. In addition, the straight light incident from the incident end face portion is reflected at the anti-incident end face portion and travels from the anti-incident end face portion to the incident end face portion without breaking the critical angle while traveling to the anti-incident end face portion. A thin plate that minimizes the thickness of the front and back surfaces at the incident end face so as to break the critical angle during the process, and maximizes the thickness of the front and back faces away from the incident end face. A rectangular cube shaped light guide plate,
The incident end face portion is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end face portion, and the distance is maximized at the end corner of the maximum separation distance from the incident end face portion, The back surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the direction of the end corner opposite to the incident end surface portion are alternately connected, and the surface portion has a convex section. A light deflecting element extending in the direction of the incident end face is provided in the shape or / and the concave shape, and the second inclined face is centered at the same distance from the two side faces, and the center is a circle close to the direction of the incident end face The arc-shaped and anti-incident end surface portion has an arc shape in which the center position of the same distance position swells from the two side surface portions .

The light guide plate according to claim 2 is an incident end face part that guides light from a point light source, an anti-incident end face part that reflects light and is positioned other than the incident end face part, and a front surface part and / or a rear surface that emits light. While the straight light incident from the incident end face portion does not break the critical angle while traveling to the anti-incident end face portion, it is reflected by the anti-incident end face portion and proceeds from the anti-incident end face portion to the incident end face portion. In order to break the critical angle, the thickness of the front and back surfaces is minimized at the incident end face, and the thickness of the front and back faces is maximized as the distance from the incident end face increases. A cube-shaped light guide plate,
The incident end face portion is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end face portion, and the distance is maximized at the end corner of the maximum separation distance from the incident end face portion, The back surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the direction of the end corner opposite to the incident end surface portion are alternately connected, and the surface portion has a convex section. A light deflecting element extending in the direction of the incident end face is provided in the shape or / and the concave shape, and the second inclined face is centered at the same distance from the two side faces, and the center is a circle close to the direction of the incident end face The arc-shaped and anti-incident end face part is an arc shape with the center position of the same distance position swelled from the two side face parts. Therefore, when the straight light from the point light source travels away from the incident end face part, it is wedge-shaped. The surface portion and the taper leak due to the inclination of the light guide plate itself The angle of total reflection at the surface portion changes to a larger angle toward the anti-incident end surface portion other than the incident end surface portion, and is reflected by the anti-incident end surface portion that reflects light and proceeds to the incident end surface portion. A taper leak occurs at the inclined surface portion of 1 or the light close to the critical angle due to total reflection travels toward the surface portion. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. Furthermore, it is possible to obtain a light condensing property on the reflected light at the anti-incident end surface portion, and the surface portion is provided by the light deflecting portion whose cross section provided on the surface portion extends in the direction of the convex or concave incident end surface portion. It is possible to condense the light that has traveled to, and emit it in a direction substantially perpendicular to the surface portion.
In addition, since the light guide plate itself has a shape in which the thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion increases, The reflection of strong light from the light source in the vicinity of the part can be avoided.

Furthermore, the light guide plate according to claim 3 is characterized in that the cross-sectional shape of the light deflecting portion has an arc shape or a triangular shape, and the inclined surface is straight or curved or the top of the cross-section is notched flat.

In the light guide plate according to claim 3 , since the cross-sectional shape of the light deflecting portion has an arc shape or a triangular shape and the inclined surface is straight or curved or the top of the cross section is cut out flat, the light totally reflected from the back surface portion. Has a spread in the direction of the side surface, is deflected by the inclined surface of the light deflection unit, and can be condensed in the upward direction of the top of the light deflection unit.

  When the top of the ridge is cut out flat, the light that is totally reflected from the back surface and reaches the flat portion of the top is directly emitted from the front surface and is deflected by another inclined surface.

Furthermore, the light guide plate according to claim 4 is characterized in that the cross section of the light deflection portion is maximized at the maximum distance from the incident end surface portion, and becomes smaller as it approaches the incident end surface portion.

In the light guide plate according to the fourth aspect , the cross section of the light deflection section becomes the maximum at the maximum distance from the incident end face portion, and becomes smaller as it approaches the incident end face portion. Since the area is increased, even light with a spread increases in the direction toward the anti-incident end face, and the amount of light reflected by the anti-incident end face can be increased.

  In addition, in the total reflected light from the gentle inclined surface such as the first inclined surface portion provided on the back surface portion toward the incident end surface portion, the inclination of the first inclined surface portion and the inclination of the light deflecting portion are always in opposite directions. It is suitable. For this reason, even the reflected light having a large reflection angle that is totally reflected with a small inclination like the first inclined surface portion can be emitted by the light deflecting unit with a small exit angle corresponding to the inclination of the light deflecting unit.

  Furthermore, the inclination of the second inclined surface portion provided on the back surface portion is larger than the inclination of the light deflection portion. Therefore, when the incident angle to the surface portion of the light totally reflected by the second inclined surface portion is equal to the inclination of the light deflecting portion, the emitted light is emitted without being deflected by the light deflecting portion, but the second inclined surface portion. Thus, the light totally reflected perpendicularly to the light deflecting part is emitted in the direction of the slightly incident end face part.

Further, the flat illumination device according to claim 5 is a linear light source, an incident end face part that guides light from the linear light source, an anti-incident end face part that is located on the opposite side of the incident end face part and reflects light, It has a front surface portion that emits the light, a back surface portion that is located on the opposite side of the front surface portion, and a side surface portion that intersects the front surface portion and the back surface portion, and the straight light incident from the incident end surface portion is the anti-incident end surface portion. The thickness of the front surface portion and the back surface portion at the incident end surface portion is such that the critical angle is not broken while traveling to the incident end surface portion but is reflected at the anti-incident end surface portion and travels from the anti-incident end surface portion to the incident end surface portion. The outer shape is such that the thickness of the front surface portion and the back surface portion is maximized at the anti-incident end surface portion, and the back surface portion is sharp with a gentle first inclined surface portion facing the anti-incident end surface portion. A staircase shape is formed in which the second inclined surface portions are alternately and continuously connected, and the surface portion has a convex cross section. Together with providing a light deflecting portion extending to the incident end face and counter-incident end face direction and / concave shape, the second inclined surface portion is from two side portions around the same length position, centered incident end face A light guide plate having an arc shape close to the direction, and the anti-incident end surface portion having an arc shape in which the center position of the same distance position swells from the two side surface portions ;
And a reflector having reflectivity that covers portions other than the incident end face portion and the surface portion of the light guide plate.

The flat illumination device according to claim 5 includes a linear light source, an incident end surface portion that guides light from the linear light source, an anti-incident end surface portion that reflects light and is located on the opposite side of the incident end surface portion, and the light. A surface portion that emits light, a back surface portion that is located on the opposite side of the front surface portion, and a side surface portion that intersects the surface portion and the back surface portion, and straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. The thickness of the front and back surfaces of the incident end face is such that the critical angle is not broken while the critical angle is broken while traveling from the anti-incident end face to the incident end face without being broken. The outer shape is minimized and the thickness of the front surface portion and the back surface portion is maximized at the anti-incident end surface portion, and the back surface portion has a gentle first inclined surface portion and a sharp second surface facing the anti-incident end surface portion. A stepped shape in which the inclined surface portions are alternately and continuously connected, and the surface portion has a convex shape or / Together provided a light deflecting portion extending to the incident end face and counter-incident end face direction in a concave shape and the second inclined surface portion is centered on the same distance position from the two side portions, the central incident end face direction A light guide plate having a circular arc shape in which the center position of the same distance position from the two side surface portions swells is formed in a close arc shape and the anti-incident end surface portion ;
A reflector having a reflective property that covers portions other than the incident end surface portion and the surface portion of the light guide plate, so that when the straight light from the light source travels from the incident end surface portion to the non-incident end surface portion, the wedge-shaped light guide plate itself It causes total reflection on the front and back surfaces without causing taper leak due to the inclination of the surface, and the angle of total reflection on the front and back surfaces changes to a larger angle toward the anti-incident end surface so that light is reflected. When the light is reflected by the anti-incident end face and proceeds to the incident end face, a taper leak occurs at the first inclined face of the back face or total reflection causes light close to the critical angle to travel toward the surface. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.

  Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, taper leak does not occur in the vicinity of the incident end face. Even with a highly directional light source, the shape of the light source such as the high-intensity emitted light near the incident end face or the semiconductor light emitting element itself is observed (reflected). ) Or brightness spots.

  Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, part of the light reflected by the anti-incident end face portion becomes closer to the critical angle while the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the first inclined surface can be reflected again into the light guide plate by the reflector.

  Furthermore, since a taper leak can occur after more light is totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not immediately exit near the incident end face part. Thereby, generation | occurrence | production of a light emission color spot can be avoided and incident light will be emitted after totally reflecting once on the opposite side of the incident-end surface part of a light-guide plate. For this reason, the light guide plate travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.

Further, the planar illumination device according to claim 6 is a prism sheet in which an acute angle portion is directed to the light guide plate direction at an upper portion on the light exit surface side of the light guide plate, and the prism portion is arranged in parallel to the incident end surface portion and the anti-incident end surface portion. It is characterized by comprising.

The flat illumination device according to claim 6 is provided with a prism sheet so that an acute angle portion is directed toward the light guide plate in the upper part on the light exit surface side of the light guide plate, and the prism portion is arranged in parallel in the incident end surface portion and the anti-incident end surface portion direction. Therefore, the reflected light from the anti-incident end face part proceeds from the anti-incident end face part toward the incident end face part, and the light directed from the light deflecting part (surface part) toward the incident end face part is the light deflecting part (surface part) of the light guide plate. ), The light emitted to the outside of the light guide plate reaches the first surface of the prism, refracts by the prism and proceeds to the inside of the prism, and then undergoes total reflection on the other surface of the prism and is substantially perpendicular to the plane of the prism. Can be emitted.

Further, the flat illumination device according to claim 7 is a linear light source, an incident end face part that guides light from the linear light source, an anti-incident end face part that is located on the opposite side of the incident end face part, and reflects light, It has a front surface portion and a back surface portion for emitting the light, and a side surface portion that intersects the front surface portion and the back surface portion, and breaks the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. First, the thickness of the front and back surfaces of the incident end surface is minimized so that the critical angle is broken while the light is reflected by the anti-incident end surface and proceeds from the anti-incident end surface to the incident end surface. The outer surface is shaped so that the thickness of the front surface portion and the back surface portion is maximized, and the back surface portion is alternately formed with a gentle first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion. Consecutively connected staircase shape, and the surface has a convex or / and concave shape in cross section Together provided a light deflecting portion extending to the end face and counter-incidence end face direction, the second inclined surface portion is from two side portions around the same length position, center an arc shape close to the incident end face direction And the anti-incident end face part is a light guide plate having an arc shape in which the center position of the same distance position swells from the two side face parts ,
And a reflector having reflectivity that covers portions other than the incident end face and the exit face of the light guide plate.

A flat illumination device according to a seventh aspect includes a linear light source, an incident end face part that guides light from the linear light source, an anti-incident end face part that is located on the opposite side of the incident end face part, and reflects the light, and the light The front and back portions that emit light, and the side portions that intersect these front and back portions, without breaking the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion, In order to break the critical angle while being reflected at the anti-incident end face portion and traveling from the anti-incident end face portion to the incident end face portion, the thickness of the front surface portion and the back surface portion is minimized at the incident end face portion, and at the anti-incident end face portion. The outer shape is such that the thickness of the front surface portion and the back surface portion is maximized, and the back surface portion is formed by alternately and gradually forming a first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion. A stepped shape connected to the surface, and the surface has a convex or / and concave cross section on the surface. And with providing the optical deflecting portion extending in the counter-incident end face direction, the second inclined surface portion is centered on the same distance position from the two side portions, center an arc shape close to the incident end face direction, and The anti-incident end face part is a light guide plate having an arc shape in which the center position of the same distance position swells from the two side face parts ,
A reflector having a reflectivity that covers portions other than the incident end face and the exit face of the light guide plate, so that when the straight light from the light source travels from the incident end face to the non-incident end face, the wedge-shaped light guide plate itself It causes total reflection on the front and back surfaces without causing taper leak due to the inclination of the surface, and the angle of total reflection on the front and back surfaces changes to a larger angle toward the anti-incident end surface so that light is reflected. When the light is reflected by the anti-incident end face and proceeds to the incident end face, a taper leak occurs at the first inclined face of the back face or total reflection causes light close to the critical angle to travel toward the surface. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.

  Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face.

  Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, part of the light reflected by the anti-incident end face portion becomes closer to the critical angle while the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the first inclined surface can be reflected again into the light guide plate by the reflector.

  In addition, since a taper leak can occur after more light is totally reflected at the anti-incident end face portion, even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not immediately exit near the incident end face portion. Thereby, generation | occurrence | production of a light emission color spot can be avoided and incident light will be emitted after totally reflecting once on the opposite side of the incident-end surface part of a light-guide plate. For this reason, the light guide plate travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.

  Further, in the case of a configuration in which the back surface portion is the exit surface, the operation is the same as that when the exit surface is the surface portion, but the direction from the front surface portion, which is the direction in which the reflector is provided, to the surface portion at a substantially right angle. After the reflected light is reflected by the reflector, it enters the light guide plate (from the front surface portion) again, proceeds from the surface portion direction of the light guide plate to the inside, and exits from the back surface portion to the outside.

Furthermore, the planar illumination device according to claim 8 is a point light source,
An incident end face part for guiding light from a point light source, an anti-incident end face part that is located at a position other than the incident end face part and reflects light, and a front surface part and / or a back surface part for emitting the light, and the incident end face part In order to break the critical angle while traveling straight light incident from the counter-incident end face part while breaking the critical angle while being reflected by the anti-incident end face part and traveling from the anti-incident end face part to the incident end face part, A thin rectangular rectangular cube shape in which the thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion increases. Is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the distance between the front end surface portion is maximized at the end corner of the maximum separation distance. The first inclined surface portion and the sharp second inclined toward the end corner direction opposite to the incident end surface portion. It forms a step shape in which the inclined surface portion is continuously connected alternately, in a surface portion with providing the optical deflection element section extends on the incident end face direction in a convex shape and / or concave shape, the second inclined surface Is centered on the same distance position from the two side surfaces, the center is in an arc shape close to the direction of the incident end surface portion, and the anti-incident end surface portion is an arc shape in which the center position of the same distance position swells from the two side surface portions a light guide plate is,
And a reflector having reflectivity that covers portions other than the incident end face and the exit face of the light guide plate.

A flat illumination device according to claim 8 is a point light source,
An incident end face part for guiding light from a point light source, an anti-incident end face part that is located at a position other than the incident end face part and reflects light, and a front surface part and / or a back surface part for emitting the light, and the incident end face part In order to break the critical angle while traveling straight light incident from the counter-incident end face part while breaking the critical angle while being reflected by the anti-incident end face part and traveling from the anti-incident end face part to the incident end face part, A thin rectangular rectangular cube shape in which the thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion increases. Is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the distance between the front end surface portion is maximized at the end corner of the maximum separation distance. The first inclined surface portion and the sharp second inclined toward the end corner direction opposite to the incident end surface portion. It forms a step shape in which the inclined surface portion is continuously connected alternately, in a surface portion with providing the optical deflection element section extends on the incident end face direction in a convex shape and / or concave shape, the second inclined surface Is centered on the same distance position from the two side surfaces, the center is in an arc shape close to the direction of the incident end surface portion, and the anti-incident end surface portion is an arc shape in which the center position of the same distance position swells from the two side surface portions a light guide plate is,
And a reflective reflector that covers the portion other than the incident end face and the exit face of the light guide plate, so that when the straight light from the light source travels away from the incident end face, the wedge-shaped light guide plate itself tilts. The total reflection at the front and back surfaces without causing taper leak due to the light, and the angle of total reflection at the front and back surfaces changes to a larger angle toward the non-incident end surface other than the incident end surface, reflecting the light When the light is reflected by the anti-incident end face portion and proceeds to the incident end face portion, a taper leak occurs at the first inclined surface portion of the back surface portion, or total reflection causes light close to the critical angle to travel toward the surface portion. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.
Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion is increased. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face.

In addition, a part of the light reflected by the anti-incident end face portion becomes closer to the critical angle as the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the inclined surface portion 1 can be reflected again into the light guide plate by the reflector.

As described above, the light guide plate according to the first aspect of the present invention includes the incident end face part that guides light from the linear light source, the opposite incident end face part that is located on the opposite side of the incident end face part, and reflects the light. It has a surface part to be emitted or / and a back part, and a side part that intersects the front part and the back part, and does not break the critical angle while the straight light incident from the incident end face part proceeds to the anti-incident end face part. The thickness of the front and back surfaces of the incident end surface is minimized so that the critical angle is broken while being reflected by the anti-incident end surface and traveling from the anti-incident end surface to the incident end surface. A light guide plate having an outer shape such that the thickness of the front surface portion and the back surface portion is maximum in the portion,
The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion are alternately connected continuously, and the surface portion has a convex shape and / or a concave shape. Are provided with a light deflecting portion extending in the direction of the incident end surface portion and the anti-incident end surface portion, and the second inclined surface portion is centered at the same distance position from the two side surface portions, and the center is an arc shape close to the incident end surface portion direction. And the anti-incident end surface portion has an arc shape in which the center position at the same distance from the two side surface portions swells, so that when the straight light from the light source travels from the incident end surface portion to the anti-incident end surface portion, it has a wedge shape. No light leaks due to the inclination of the light guide plate itself, and the light is totally reflected at the front and back surfaces. The angle at which the light is totally reflected at the front and back surfaces changes to a larger angle toward the anti-incident end surface, reflecting light. Reflected by the anti-incident end face When proceeding to hurt surface, or causing tapered leak in the first inclined surface portion of the back surface, the light near the critical angle performs total reflection proceeds in the surface portion direction. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.
Therefore, the light from the light source is reflected by the counter-incident end face is totally reflected with a spread in the second inclined surface, the light can be effectively utilized to maximize the reflected light is laterally from a light source Can be mixed with each other while preventing leakage .

Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face. As a result, the amount of light can be controlled, the light source is not reflected, and both the ends of the incident end face near the incident end face have no dark portions, and bright and uniform emitted light can be obtained. As a result, the area of the light guide plate that can actually be used can be increased, and even if the light sources are arranged in parallel (array shape), the occurrence of luminance spots is prevented without overlapping light from adjacent light sources. be able to.
Further, when the size is increased, both ends are set as incident end faces, and the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

The light guide plate according to claim 2 is an incident end face part that guides light from a point light source, an anti-incident end face part that reflects light and is positioned other than the incident end face part, and a front surface part and / or a rear surface that emits light. While the straight light incident from the incident end face portion does not break the critical angle while traveling to the anti-incident end face portion, it is reflected by the anti-incident end face portion and proceeds from the anti-incident end face portion to the incident end face portion. In order to break the critical angle, the thickness of the front and back surfaces is minimized at the incident end face, and the thickness of the front and back faces is maximized as the distance from the incident end face increases. A cube-shaped light guide plate,
The incident end face portion is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end face portion, and the distance is maximized at the end corner of the maximum separation distance from the incident end face portion, The back surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the direction of the end corner opposite to the incident end surface portion are alternately connected, and the surface portion has a convex section. A light deflecting element extending in the direction of the incident end face is provided in the shape or / and the concave shape, and the second inclined face is centered at the same distance from the two side faces, and the center is a circle close to the direction of the incident end face The arc-shaped and anti-incident end face part is an arc shape with the center position of the same distance position swelled from the two side face parts. Therefore, when the straight light from the point light source travels away from the incident end face part, it is wedge-shaped. The surface portion and the taper leak due to the inclination of the light guide plate itself The angle of total reflection at the surface portion changes to a larger angle toward the anti-incident end surface portion other than the incident end surface portion, and is reflected by the anti-incident end surface portion that reflects light and proceeds to the incident end surface portion. A taper leak occurs at the inclined surface portion of 1 or the light close to the critical angle due to total reflection travels toward the surface portion. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. Furthermore, it is possible to obtain a light condensing property on the reflected light at the anti-incident end surface portion, and the surface portion is provided by the light deflecting portion whose cross section provided on the surface portion extends in the direction of the convex or concave incident end surface portion. It is possible to condense the light that has traveled to, and emit it in a direction substantially perpendicular to the surface portion.
In addition, since the light guide plate itself has a shape in which the thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion increases, It is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the portion.
Therefore, the light from the point light source reflected at the anti-incident end face part is totally reflected with a spread at the second inclined face part, and uniform outgoing light with no spots can be obtained from the outgoing face. Light from such point light sources can be mixed with each other to obtain complete white light.

In the light guide plate according to the third aspect , the cross-sectional shape of the light deflecting portion has an arc shape or a triangular shape, and the inclined surface is straight or curved, or the top of the cross section is notched flat, so that the light deflecting portion is deflected by the inclined surface of the light deflecting portion. Then, the light can be condensed in the upward direction of the top of the light deflection unit.
Therefore, for example, a sharp light beam is emitted in each direction with respect to each pixel of RGB on the LCD, so that the aperture area of the pixel can be reduced. Thus, by reducing the size of each pixel of RGB, the amount of pixels per unit area can be made finer and a clear image can be provided.

When the top of the ridge is cut out flat, the light that is totally reflected from the back surface and reaches the flat portion of the top is directly emitted from the front surface and is deflected by another inclined surface.
For this reason, not only the light that has been collected all over the top, but also the light that has a slight spread and the collected light are mixed, so that bright light can be obtained as a whole light guide plate.

In the light guide plate according to the fourth aspect , the cross section of the light deflection section becomes the maximum at the maximum distance from the incident end face portion, and becomes smaller as it approaches the incident end face portion. Since the area increases, even light that has a spread increases in the direction toward the anti-incident end face, and the amount of light reflected by the anti-incident end face can be increased.
Therefore, the amount of emitted light increases and bright emitted light can be obtained.

In addition, in the total reflected light from the gentle inclined surface such as the first inclined surface portion provided on the back surface portion toward the incident end surface portion, the inclination of the first inclined surface portion and the inclination of the light deflecting portion are always in opposite directions. Therefore, even the reflected light having a large reflection angle that is totally reflected with a slight inclination as in the first inclined surface portion can be emitted by the light deflection portion with a small emission angle corresponding to the inclination of the light deflection portion.
Therefore, there is no outgoing light having a large outgoing angle in the direction of the incident end face.

Further, since the inclination of the second inclined surface portion provided on the back surface portion is larger than the inclination of the light deflecting portion, the incident angle to the surface portion of the light totally reflected by the second inclined surface portion and the inclination of the light deflecting portion. When the two are equal, the emitted light is emitted without being deflected by the light deflecting unit, but the light totally reflected perpendicularly to the light deflecting unit by the second inclined surface part is emitted in the direction of the slightly incident end face part.
Therefore, it is possible to obtain vertical light from the light deflecting portion on the front surface portion without necessarily performing total reflection in the vertical direction on the back surface portion.

The flat illumination device according to claim 5 includes a linear light source, an incident end surface portion that guides light from the linear light source, an anti-incident end surface portion that reflects light and is located on the opposite side of the incident end surface portion, and the light. A surface portion that emits light, a back surface portion that is located on the opposite side of the front surface portion, and a side surface portion that intersects the surface portion and the back surface portion, and straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. The thickness of the front and back surfaces of the incident end face is such that the critical angle is not broken while the critical angle is broken while traveling from the anti-incident end face to the incident end face without being broken. The outer shape is minimized and the thickness of the front surface portion and the back surface portion is maximized at the anti-incident end surface portion, and the back surface portion has a gentle first inclined surface portion and a sharp second surface facing the anti-incident end surface portion. A stepped shape in which the inclined surface portions are alternately and continuously connected, and the surface portion has a convex shape or / Together provided a light deflecting portion extending to the incident end face and counter-incident end face direction in a concave shape and the second inclined surface portion is from two side portions around the same length position, center the incident end face direction A light guide plate that has an arc shape close to, and the anti-incident end surface portion has an arc shape in which the center position of the same distance position swells from the two side surface portions ,
A reflector having a reflective property that covers portions other than the incident end surface portion and the surface portion of the light guide plate, so that when the straight light from the light source travels from the incident end surface portion to the non-incident end surface portion, the wedge-shaped light guide plate itself It causes total reflection on the front and back surfaces without causing taper leak due to the inclination of the surface, and the angle of total reflection on the front and back surfaces changes to a larger angle toward the anti-incident end surface so that light is reflected. When the light is reflected by the anti-incident end face and proceeds to the incident end face, a taper leak occurs at the first inclined face of the back face or total reflection causes light close to the critical angle to travel toward the surface. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.
Therefore, the light from the light source reflected by the anti-incident end face part is totally reflected by the second inclined face part with a spread, and the light can be used to the maximum extent effectively. can be obtained emitted light, reflected light from the light source Ru can be mixed with one another while hardly leaks from the side.

Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, taper leak does not occur in the vicinity of the incident end face. Even with a highly directional light source, the shape of the light source such as the high-intensity emitted light near the incident end face or the semiconductor light emitting element itself is observed (reflected). ) Or brightness spots.
Therefore, the amount of light can be controlled and there is no reflection of the light source, and both ends of the incident end face near the incident end face can be obtained with no dark part and bright and uniform outgoing light can be obtained. Large area of the light guide plate.

Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, part of the light reflected by the anti-incident end face portion becomes closer to the critical angle while the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the first inclined surface can be reflected again into the light guide plate by the reflector.
Therefore, light from the light source can be used without waste, and all light can be emitted from the emission surface.

Furthermore, since a taper leak can occur after more light is totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not immediately exit near the incident end face part. Thereby, generation | occurrence | production of a light emission color spot can be avoided and incident light will be emitted after totally reflecting once on the opposite side of the incident-end surface part of a light-guide plate. For this reason, the light guide plate travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.
Therefore, even if the light sources are arranged in parallel (array shape), it is possible to use any type of light source so that the light from adjacent light sources can be prevented from overlapping without causing luminance spots. Light source of semiconductor light emission such as RGB can be used as the light source, and it is possible to obtain a flat illumination device that is light weight, downsized, mechanical strength, light emission in low temperature environment, power saving, high brightness and environment friendly it can.
Further, when the size is increased, both ends are set as incident end faces, and the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

The flat illumination device according to claim 6 is provided with a prism sheet so that an acute angle portion is directed toward the light guide plate in the upper part on the light exit surface side of the light guide plate, and the prism portion is arranged in parallel in the incident end surface portion and the anti-incident end surface portion direction. Therefore, the reflected light from the anti-incident end face part proceeds from the anti-incident end face part toward the incident end face part, and the light directed from the light deflecting part (surface part) toward the incident end face part is the light deflecting part (surface part) of the light guide plate. ) Is emitted to the outside of the light guide plate to reach one surface of the prism, and is refracted by the prism and proceeds to the inside of the prism, and then is totally reflected by the other surface of the prism and Can be emitted substantially vertically.
Therefore, all the light emitted from the surface portion can be emitted substantially vertically, and bright emitted light can be obtained.

A flat illumination device according to a seventh aspect includes a linear light source, an incident end face part that guides light from the linear light source, an anti-incident end face part that is located on the opposite side of the incident end face part, and reflects the light, and the light The front and back portions that emit light, and the side portions that intersect these front and back portions, without breaking the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion, In order to break the critical angle while being reflected at the anti-incident end face portion and traveling from the anti-incident end face portion to the incident end face portion, the thickness of the front surface portion and the back surface portion is minimized at the incident end face portion, and at the anti-incident end face portion. The outer shape is such that the thickness of the front surface portion and the back surface portion is maximized, and the back surface portion is formed by alternately and gradually forming a first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion. A stepped shape connected to the surface, and the surface has a convex or / and concave cross section on the surface. And with providing the optical deflecting portion extending in the counter-incident end face direction, the second inclined surface portion is centered on the same distance position from the two side portions, center an arc shape close to the incident end face direction, and The anti-incident end face part is a light guide plate having an arc shape in which the center position of the same distance position swells from the two side face parts ,
A reflector having a reflectivity that covers portions other than the incident end face and the exit face of the light guide plate, so that when the straight light from the light source travels from the incident end face to the non-incident end face, the wedge-shaped light guide plate itself It causes total reflection on the front and back surfaces without causing taper leak due to the inclination of the surface, and the angle of total reflection on the front and back surfaces changes to a larger angle toward the anti-incident end surface so that light is reflected. When the light is reflected by the anti-incident end face and proceeds to the incident end face, a taper leak occurs at the first inclined face of the back face or total reflection causes light close to the critical angle to travel toward the surface. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion.
Therefore, the light from the light source reflected by the anti-incident end face part is totally reflected by the second inclined face part with a spread, and the light can be used to the maximum extent effectively. can be obtained emitted light, reflected light from the light source Ru can be mixed with one another while hardly leaks from the side.

Further, the light guide plate of the present invention has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face.
As a result, the amount of light can be controlled and there is no reflection of the light source, and both ends of the incident end surface near the incident end surface can be obtained with no dark areas, and bright and uniform outgoing light can be obtained, and can be used for that. The area of the obtained light guide plate can be increased.

Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the surface portion and the back surface portion is maximized at the anti-incident end surface portion. For this reason, part of the light reflected by the anti-incident end face portion becomes closer to the critical angle while the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the first inclined surface can be reflected again into the light guide plate by the reflector.
Therefore, light from the light source can be used without waste, and all light can be emitted from the emission surface.

Furthermore, since a taper leak can occur after more light is totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not immediately exit near the incident end face part. Thereby, generation | occurrence | production of a light emission color spot can be avoided and incident light will be emitted after totally reflecting once on the opposite side of the incident-end surface part of a light-guide plate. For this reason, the light guide plate travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.
Therefore, even if the light sources are provided in parallel (array shape), it is possible to use any type of light source so as to prevent the occurrence of luminance spots without overlapping light from adjacent light sources.
Further, when the size is increased, both ends are set as incident end faces, and the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

Further, in the case of a configuration in which the back surface portion is the exit surface, the operation is the same as that when the exit surface is the surface portion, but the direction from the front surface portion, which is the direction in which the reflector is provided, to the surface portion at a substantially right angle. After the reflected light is reflected by the reflector, it enters the light guide plate (from the front surface portion) again, proceeds from the surface portion direction of the light guide plate to the inside, and exits from the back surface portion to the outside.
Therefore, the reflected light from the anti-incident end face portion does not directly exit from the exit surface (back surface portion), and almost vertical light can be emitted from the exit surface (back surface portion).

A flat illumination device according to claim 8 is a point light source,
An incident end face part for guiding light from a point light source, an anti-incident end face part that is located at a position other than the incident end face part and reflects light, and a front surface part and / or a back surface part for emitting the light, and the incident end face part In order to break the critical angle while traveling straight light incident from the counter-incident end face part while breaking the critical angle while being reflected by the anti-incident end face part and traveling from the anti-incident end face part to the incident end face part, A thin rectangular rectangular cube shape in which the thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion increases. Is provided at one end of the light guide plate, the distance between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the distance between the front end surface portion is maximized at the end corner of the maximum separation distance. The first inclined surface portion and the sharp second inclined toward the end corner direction opposite to the incident end surface portion. It forms a step shape in which the inclined surface portion is continuously connected alternately, in a surface portion with providing the optical deflection element section extends on the incident end face direction in a convex shape and / or concave shape, the second inclined surface Is centered on the same distance position from the two side surfaces, the center is in an arc shape close to the direction of the incident end surface portion, and the anti-incident end surface portion is an arc shape in which the center position of the same distance position swells from the two side surface portions a light guide plate is,
And a reflective reflector that covers the portion other than the incident end face and the exit face of the light guide plate, so that when the straight light from the light source travels away from the incident end face, the wedge-shaped light guide plate itself tilts. The total reflection at the front and back surfaces without causing taper leak due to the light, and the angle of total reflection at the front and back surfaces changes to a larger angle toward the non-incident end surface other than the incident end surface, reflecting the light When the light is reflected by the anti-incident end face portion and proceeds to the incident end face portion, a taper leak occurs at the first inclined surface portion of the back surface portion, or total reflection causes light close to the critical angle to travel toward the surface portion. Further, the second inclined surface portion of the back surface portion has a small reflection angle of total reflection and proceeds at an angle substantially perpendicular to the surface portion, and totally reflects the reflected light from the anti-incident end surface portion with a spread in the surface portion direction. In addition, it is possible to obtain the light condensing property on the reflected light at the anti-incident end face part, and the light deflection in which the cross section provided on the surface part extends toward the convex or concave incident end face part and the anti-incident end face part. By the portion, the light traveling to the surface portion can be condensed and emitted in a direction substantially perpendicular to the surface portion. Therefore, the light from the light source reflected by the anti-incident end face part is totally reflected by the second inclined face part with a spread, and the light can be used to the maximum extent effectively. can be obtained emitted light, reflected light from the light source Ru can be mixed with one another while hardly leaks from the side.

Further, the light guide plate itself has a shape in which the thickness between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness between the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion is increased. For this reason, it is possible to avoid reflection of strong light from the light source in the vicinity of the incident end face without generating a taper leak in the vicinity of the incident end face.

In addition, a part of the light reflected by the anti-incident end face portion becomes closer to the critical angle as the total reflection is repeated many times between the front surface portion and the back surface portion, and the inclination angle of the first inclined surface portion is small. The light emitted from the back surface by the minute light breaking the critical angle at the inclined surface portion 1 can be reflected again into the light guide plate by the reflector. Therefore, light from the light source can be used without waste, and all light can be emitted from the emission surface.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the light guide plate of the present invention, the distance between the front surface portion and the back surface portion is the minimum at the incident end surface portion, the distance is maximum at the maximum separation distance from the incident end surface portion, and the back surface portion is the incident end surface portion. The first inclined surface portion and the sharp second inclined surface portion facing in the opposite direction to each other form a stepped shape in which the first and second inclined surface portions are alternately and continuously connected. These surfaces form a mirror surface, and collect light on the surface portion. An optical deflection unit is provided.

Moreover, the flat illuminating device of this invention comprises the said light guide plate, a linear light source, a point light source, and the reflector with the reflectivity which covers parts other than the entrance-end surface part and output surface of a light-guide plate. It is. With the above configuration, the present invention can control the reflection of the light source near the incident end face portion of the light guide plate, the occurrence of luminance spots and light emission color spots, and can lead to a large use exit surface of the light guide plate. An optical plate and a flat illumination device are provided.

  1 to 7 are schematic perspective views of a flat illumination device according to the present invention, FIG. 8 is a schematic cross-sectional view and a trajectory diagram of the concept of the light guide plate according to the present invention, and FIG. 9 is a schematic cross-sectional view of the light guide plate according to the present invention. 10 is a schematic front view and a trajectory diagram of the light guide plate according to the present invention, FIG. 11 is a schematic cross-sectional view and a trajectory diagram of the light guide plate according to the present invention, and FIG. 12 is a schematic back surface of the light guide plate according to the present invention. 13 is a schematic perspective view of a flat illumination device according to the present invention, FIG. 14 is a partially enlarged view of a light guide plate according to the present invention, FIG. 15 is a schematic perspective view of the flat illumination device according to the present invention, and FIG. FIG. 17 is a schematic perspective view of a flat illumination device according to the present invention, and FIG. 18 is a schematic cross-sectional view and a trajectory diagram of the flat illumination device according to the present invention.

  A flat illumination device 1 shown in FIG. 1 includes a light guide plate 2, a light source 10, and a reflector 11 and is schematically configured.

The light guide plate 2 is formed of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7. The light guide plate 2 includes an incident end face portion 3 that guides light from the light source 10, a counter incident end face portion 4 that is located on the opposite side of the incident end face portion 3, a surface portion 8 that emits light, and the surface portion 8. It consists of a back surface portion 5 located on the opposite side, and a front surface portion 8 and a side surface portion 14 connected to the back surface portion 5.
Here, although the incident end surface portion 3 uses one side surface of the rectangular light guide plate 2, the incident end surface portion 3 may be anywhere on the peripheral side of the light guide plate 2, and the shape is not defined.

In the light guide plate 2, the distance between the front surface portion 8 and the back surface portion 5 (thickness of the light guide plate 2) is minimum (thin) at the incident end surface portion 3, and the maximum separation distance ( The anti-incident end face portion 4) located on the opposite side of the incident end face portion 3 has a shape in which the distance (thickness) is maximized (thick). The light source 10 is disposed in the vicinity of the incident end face portion 3 where the thickness of the light guide plate 2 is thin, and the light guide plate 2 is disposed on the opposite side (maximum separation distance) of the light guide plate 2.
Although not shown, the anti-incidence end face portion 4 is provided with a reflector so as to be reflected or reflected by the reflector 11.

  Further, the back surface portion 5 of the light guide plate 2 has a first inclined surface portion 6 and a sharp second inclined surface portion 7 alternately and continuously facing the direction opposite to the incident end surface portion 3 (the anti-incident end surface portion 4). It has a connected staircase shape. Note that the surfaces of the first inclined surface portion 6 and the second inclined surface portion 7 are mirror surfaces.

Further, the light incident on the light guide plate 2 travels into the light guide plate 2 in a range where the refraction angle γ satisfies the expression 0 ≦ | γ | ≦ Sin ⁻¹ (1 / n). For example, since the refractive index of acrylic resin, which is a resin material used for a general light guide plate 2, is about n = 1.49, light from the front surface portion 8 direction of the incident end surface portion 3 to the rear surface portion 5 direction and the back surface The maximum incident angle of light from the portion 5 direction to the surface portion 8 direction is 90 °, and the refraction angle γ refracted at the incident end surface portion 3 is in the range of γ = 0 to ± 42 °.
However, only γ = −42 ° only in the direction of the back surface 5 near the front surface portion 8 and only γ = + 42 ° only in the direction of the front surface portion 8 near the back surface portion 5.

  Further, the light incident on the light guide plate 2 within the range of the refraction angle γ = 0 to ± 42 ° is Sin α = (1 / n) at the boundary surface between the light guide plate 2 and the air layer (refractive index n = 1). ) Can be used to express the critical angle. For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 2, is about n = 1.49, the critical angle α is about α = 42 °, and the surface portion 8 of the light guide plate 2 And the rear surface portion 5 has no groove for deflecting the light beam, or the entire inclination angle so that the thickness of the light guide plate 2 gradually decreases from the direction of the incident end surface portion 3 of the light guide plate 2 is about 6 °. If the critical angle α is not exceeded, the light in the light guide plate 2 travels in the direction toward the anti-incident end face part 4 while being totally reflected by the front face part 8 and the back face part 5.

However, in the light guide plate 2 of the present invention, the thickness (the distance between the front surface portion 8 and the back surface portion 5) is directed from the incident end surface portion 3 to the anti-incident end surface portion 4 located on the opposite side of the incident end surface portion 3. Wedge shape that becomes thicker (thickest at the maximum separation distance from the incident end face portion 3) (opposite to the wedge shape that decreases in thickness toward the maximum separation distance from the incident end face portion as in a general or conventional light guide plate) It is. Accordingly, as shown in FIG. 8, even if the light guide plate 2 is wedge-shaped while the incident light Ln1 from the incident end surface portion 3 proceeds to the counter incident end surface portion 4 located on the opposite side of the incident end surface portion 3, it is critical. There is no light beam that breaks the corner, and the light beam Ln2 that has undergone total reflection at the front surface portion 8 and the back surface portion 5 undergoes total reflection at the anti-incident end surface portion 4, and the reflected light beam Ln3 reaches the surface portion 8 at an angle close to the critical angle α. The incident angle with respect to the surface portion (tilt) of the light guide plate 2 breaks the critical angle α, and the light beam Ln4 can be emitted from the surface portion 8.
In addition, the gentle 1st inclined surface part 6 and the sharp 2nd inclined surface part 7 which face the counter-incident end surface part 4 which is the opposite direction of the incident end surface part 3 in the back surface part 5 of the light-guide plate 2 of FIG. 8 here. Although not shown, the back surface portion 5 as one gentle inclined surface is shown so that the overall shape and the like can be easily understood.

  Further, as shown in FIG. 9, the back surface portion 5 of the light guide plate 2 includes a gentle first inclined surface portion 6 and a sharp second inclined surface portion 7 facing the counter-incident end surface portion 4 which is opposite to the incident end surface portion 3. And have a staircase shape that is continuously connected alternately. Moreover, these surfaces are mirror surfaces.

The light guide plate 2 is substantially wedge-shaped, and has a staircase shape in which gentle first inclined surface portions 6 and sharp second inclined surface portions 7 directed to the anti-incident end surface portion 4 are alternately and continuously connected. There is no light beam that breaks the critical angle while the incident light Ln1 from the incident end surface portion 3 travels to the counter-incident end surface portion 4 located on the opposite side of the incident end surface portion 3, and a gentle first of the front surface portion 8 and the back surface portion 5 is observed. The total reflection is repeated at the inclined surface portion 6 and the sharp second inclined surface portion 7, reaches the anti-incident end surface portion 4, undergoes total reflection at the anti-incident end surface portion 4, and the totally reflected light beam Ln 2 travels again in the direction of the incident end surface portion 3. . At this time, the taper leak hardly occurs in the gentle first inclined surface portion 6, and even when it occurs, the light is emitted at a large emission angle along the back surface portion 5.
Further, even when a taper leak occurs from the surface portion 8 due to total reflection at the gentle first inclined surface portion 6, the light is emitted at a large emission angle along the surface portion 8.

  However, since the light beam that has reached the sharp second inclined surface portion 7 is a light beam that is likely to cause a taper leak, it is totally reflected by the second inclined surface portion 7 and the light beam Ln3 proceeds in the direction of the surface portion 8, The light beam Ln4 can be emitted from the portion 8 at a substantially right angle.

Further, the second inclined surface portion 7 can perform total reflection with a large deflection angle even if it is not a light beam close to the critical angle, and can emit substantially vertical light or a wide range of light directly from the surface portion 8.
For this reason, taper leak does not occur in the vicinity of the incident end face 3, and therefore the shape of the light source 10 such as high-intensity emitted light near the incident end face 3 or the semiconductor light-emitting element itself is different from the exit face even in the light source 10 with high directivity. There is no observation (reflection) or brightness spots.

  Furthermore, since a taper leak or the like can be caused only by the light beam totally reflected at the anti-incident end face portion 4, even in the case of the light source 10 in which the monochromatic light sources 10 such as RGB are arranged, the light does not immediately emit in the vicinity of the incident end face portion 3. Thereby, generation | occurrence | production of the light emission color spot can be avoided, and incident light is once reflected in the opposite side of the incident-end surface part 3 of the light-guide plate 2, and is emitted. For this reason, the light guide plate 2 travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.

  Further, the second inclined surface portion 7 can totally reflect even a light beam that is not close to the critical angle, and can be directly emitted from the surface portion 8 substantially perpendicularly. The substantially perpendicular emitted light is incident on the incident end face portion 3 and the anti-incident end face. Propagation in the direction of the portion 4 can be emitted as a light beam having a sharp peak width.

Further, the surface portion 8 of the light guide plate 2 is provided with a light deflecting portion 8a having a convex or / and concave cross section so as to extend in the direction of the incident end surface portion 3 and the anti-incident end surface portion 4.
Note that the surfaces of the light deflecting portion 8a and the surface portion 8 are mirror surfaces.

The light deflection section 8a shown in FIG. 1 has a triangular shape 12 in cross section, and a convex shape and a concave shape are arranged in parallel.
Further, the light deflection unit 8a shown in FIG. 2 has a circular arc shape 13 having a convex cross section, and the convex shapes are continuously arranged side by side.
Further, the light deflecting portion 8a shown in FIG. 3 has triangular shapes 12 having a convex cross section, and a plane (mirror surface) 8b of the surface portion 8 exists between the triangular shapes 12.
Further, the light deflecting portion 8a shown in FIG. 4 is provided with a circular arc shape 13 having a convex cross section, and a plane (mirror surface) 8b of the surface portion 8 exists between the circular arc shapes 13.

  Then, as shown in FIGS. 10 (10a, 10b), these light deflecting portions 8a have a cross-sectional shape that is convex outward. For this reason, the totally reflected light Lr from the first inclined surface portion 6 and the second inclined surface portion 7 of the back surface portion 5 travels in the direction of the light deflecting portion 8a of the front surface portion 8, and air in a triangular shape (refracted). Refracted at a boundary portion with a space having a different rate) and a boundary portion with air of the arc shape 13 (space having a different refractive index), and the refracted light Lrr travels in the direction of the top of the triangular shape 12 or the arc shape 13. Then, the refracted lights Lrr intersect from the inclined surfaces in the different directions so that the light is condensed in the upper position direction of the top of the triangular shape 12 or the arc shape 13 by the inclined surfaces in the different directions of the light deflecting portions 8a. The light is emitted from the light deflection unit 8a.

As shown in FIG. 14, the cross-sectional shape of the light deflector 8a is such that the inclined surface of the triangular shape 12 is a straight line (straight inclined surface 12 in FIG. 14A) or a curved line (FIGS. 14B and 14C). Curve inclined surfaces 12c1, 12c2). As a result, the light is deflected by the inclined surface of the light deflection unit 8a and can be condensed in the upward direction of the top of the light deflection unit 8a.
Further, if the straight inclined surface 12 of FIG. 14 (a) is a standard, the concave curved inclined surface 12c1 of FIG. 14 (b) collects light with a slight spread, and the convex curved inclined surface of FIG. 14 (c). 12c2 is more concentrated.
In the case of the concave curved inclined surface 12c1 in FIG. 14B, depending on the curvature and the overall inclination, the light deflecting portion 8a does not transmit (refract) but totally reflects and faces the inclined surface facing the opposite inclined surface 5 direction. Returned to

  In any case, the shape of these inclined surfaces has a condensing function, and particularly when condensing sharply, for example, a sharp luminous flux is emitted in each direction with respect to each RGB pixel in the LCD. The opening area can be reduced. Thus, by reducing the size of each pixel of RGB, the amount of pixels per unit area can be made finer and a clear image can be provided.

  Furthermore, as shown in FIGS. 14D to 14F, the cross-sectional shape of the light deflection portion 8a is the top of the triangular shape 12 in FIG. 14A or the arc shape 13 in FIG. 14G. Can be flattened (flat surfaces 12c3 to 12c5, 13c1 of (d) to (f) and (h) of FIG. 14). Thereby, the light that is totally reflected from the back surface portion 5 and reaches the flat portion at the top portion is emitted from the front surface portion 8 as it is and is deflected by the other side surface portion.

  Therefore, not only all the light collected above the top, but also a slightly broadened light and the collected light are mixed, so that the light guide plate 2 as a whole can obtain bright outgoing light.

  Further, as shown in FIGS. 5 and 6, the light deflection portion 8 a is provided so that the cross section of the triangular shape 12 b or the arc shape 13 b is maximized at the anti-incident end face portion 4 and becomes smaller as it approaches the incident end face portion 3. Can do.

As shown in FIG. 11, the light Lrc having the maximum total reflection angle from the first inclined surface portion 6 provided on the back surface portion 5 toward the incident end surface portion 3 with respect to the triangular shape 12b or the arc shape 13b enters the light deflection portion 8a. The emission light Lrco having a small emission angle corresponding to the inclination angle of the light deflection unit 8a is emitted.
Similarly, the light Lr having a certain reflection angle reaches the light deflection unit 8a, and emits the outgoing light Lro having a smaller emission angle by the inclination angle of the light deflection unit 8a.

Here, in order to contrast with the present invention, when the surface portion 8 indicated by the dotted line is flat, the light of the maximum total reflection angle light Lrc from the same first inclined surface portion 6 toward the incident end surface portion 3 is obtained. Is emitted at a large emission angle and is emitted in a state along the surface portion 8 like the emitted light Lrcm.
Similarly, the light Lr having a certain reflection angle toward the incident end face 3 is emitted at a large emission angle, and is emitted in a state along the surface portion 8 to some extent like the emission light Lrm.

As described above, in the total reflected light from the gentle inclined surface such as the first inclined surface portion 6 provided on the back surface portion 5 toward the incident end surface portion 3, the inclination of the first inclined surface portion 6 and the light deflecting portion 8a. The tilt is always in the opposite direction. As a result, even the light having a large reflection angle that is totally reflected with a small inclination like the first inclined surface portion 6 can be emitted by the light deflection unit 8a with a small emission angle by the inclination of the light deflection unit 8a.
Therefore, there is no outgoing light having a large outgoing angle along the surface portion 8 of the light guide plate 2 in the direction of the incident end face portion 3.

Similarly, as shown in FIG. 11, the reflection in which the light toward the incident end surface portion 3 is totally reflected substantially vertically by the second inclined surface portion 7 provided on the back surface portion 5 with respect to the triangular shape 12b or the arc shape 13b. The light Lrs reaches the light deflector 8 a, and the inclination angle of the light deflector 8 a absorbs the refraction of the light guide plate 2, and emits the emitted light Lrso perpendicular to the surface portion 8.
Further, the reflected light Lrr, which is the total reflected light vertically toward the incident end surface 3 by the second inclined surface portion 7 provided on the back surface portion 5, reaches the light deflection portion 8a, and the inclination angle of the light deflection portion 8a is equal to the angle of inclination. It is larger than the refraction of the light guide plate 2. For this reason, the emitted light Lrro is emitted substantially perpendicularly to the surface portion 8 in the direction opposite to the anti-incident end face portion 4.

Thus, the inclination of the second inclined surface portion 7 provided on the back surface portion 5 is larger than the inclination of the light deflection portion 8a. For this reason, when the incident angle to the surface portion 8 of the light totally reflected by the second inclined surface portion 7 is equal to the inclination of the light deflection portion 8a, the emitted light is emitted without being deflected by the light deflection portion 8a. The light totally reflected perpendicularly to the light deflecting portion 8 a by the two inclined surface portions 7 is emitted in the direction of the slightly incident end face portion 4.
Thereby, it is possible to obtain vertical light from the light deflecting portion 8a of the front surface portion 8 without necessarily making the back surface portion 5 totally reflect in the vertical direction.

The light source plate 2c of the flat illumination device 1b in which the point light source 10 in FIG. 13 is provided in at least one corner and the surface 8 is provided with the light deflecting portion 8a having the arc shape 13b, and the light deflection in FIG. Since the action of light in the light guide plate 2c of the flat illumination device 1b in which the portion 8a is provided with the triangular shape 12b is the same, the description thereof is omitted.

As shown in FIGS. 7 and 12, the flat illumination device 1 d has an arc shape in which the counter-incident end surface portion 4 d of the light guide plate 2 b swells at the center position at the same distance from the two side surface portions 14.
Further, the second inclined surface portion 7d provided on the back surface portion 5 has a shape that is centered on the same distance position from the two side surface portions 14 and has an arc shape whose center is close to the incident end surface portion 3 direction.
Note that the light deflecting portion 8a provided on the surface portion 8 of the light guide plate 2b in FIG. 7 is omitted.

  Therefore, it is possible to obtain a light condensing property for the reflected light at the anti-incident end surface portion 4d. For example, in the case of a plurality of point light sources 10 and the like, the reflected light from the light source 10 can be mixed with each other while being difficult to leak from the side surface portion 14 direction.

  Further, the second inclined surface portion 7d can totally reflect the reflected light from the anti-incident end surface portion 4d with a spread in the surface portion 8 direction. In particular, when a plurality of directional point light sources 10 are used, the light from each point light source 10 reflected by the anti-incident end surface portion 4d is totally reflected by the second inclined surface portion 7d. Thus, uniform emission light without spots can be obtained from the emission surface 8. For example, light from point light sources 10 such as RGB can be mixed with each other to obtain complete white light.

  Furthermore, as shown in FIG. 15, the flat illumination device 1 c uses the front surface portion 8 of the light guide plate 2 facing downward in the direction of the reflector 11 and the back surface portion 5 toward the emission direction. A first inclined surface portion 6 and a second inclined surface portion 7 are provided, and a light deflecting portion 8 a having a triangular shape 12 or an arc shape 13 in cross section is provided downward in the direction of the reflector 11. The light deflecting portion 8a in FIG. 15 has a triangular cross section of 12.

Although not shown, the light guide plate 2 is substantially wedge-shaped while incident light from the incident end surface portion 3 travels to the non-incident end surface portion 4 located on the opposite side of the incident end surface portion 3, and is provided on the exit surface (back surface portion 5). Even if the first inclined surface portion 6 and the sharp second inclined surface portion 7 facing the anti-incident end surface portion 4 are alternately and continuously connected, there is no light beam that breaks the critical angle, and the surface portion 8 And the first inclined surface portion 6 and the sharp second inclined surface portion 7 of the back surface portion 5 are repeatedly totally reflected, reach the anti-incident end surface portion 4 and totally reflected by the anti-incident end surface portion 4, and are totally reflected. Again proceeds in the direction of the incident end face 3. At this time, the taper leak hardly occurs in the gentle first inclined surface portion 6, and even when it occurs, the light is emitted at a large emission angle along the back surface portion 5.
Further, even when a taper leak occurs from the surface portion 8 due to total reflection at the gentle first inclined surface portion 6, the light is emitted at a large emission angle along the surface portion 8.

  Similarly, as shown in FIG. 16, the reflected light Lr1 reflected by the anti-incident end surface portion 4 reaches the sharp second inclined surface portion 7, is totally reflected, and the light beam Lr2 is reflected by the lower surface portion 8 (light deflecting portion). 8a), the light is condensed by the light deflecting portion 8a, refracted to the outside from the surface portion 8 (light deflecting portion 8a), and the light beam Lro1 is emitted. The light beam Lro1 reaches the reflector 11 provided under the light guide plate 2, is reflected by the reflector 11, and the reflected light Lrr again travels to the light guide plate 2, and is refracted by the front surface portion 8 (light deflecting portion 8a) and back surface. The light Lri travels in the direction of part 5. This light Lri is further refracted by the gentle first inclined surface portion 6 and can be emitted to the outside as outgoing light Lro2.

  Similarly, since the taper leak does not occur near the incident end face 3, the shape of the light source 10 such as the high-intensity emitted light near the incident end face 3 or the semiconductor light emitting element itself can be obtained even when the light source 10 has high directivity. There are no observations (reflections) or luminance spots.

Furthermore, since a taper leak or the like can be caused only by the light beam totally reflected at the anti-incident end face portion 4, even in the case of the light source 10 in which the monochromatic light sources 10 such as RGB are arranged, the light does not immediately emit in the vicinity of the incident end face portion 3. Thereby, generation | occurrence | production of the light emission color spot can be avoided, and incident light is once reflected in the opposite side of the incident-end surface part 3 of the light-guide plate 2, and is emitted. For this reason, the light guide plate 2 travels while repeating total reflection several times in the meantime, and RGB monochromatic light is mixed to obtain complete white light.
In addition, about the different shape of the light deflection | deviation part 8a of FIG. 2, and the planar illuminating device 1c which comprised the back surface part 5 of the light-guide plate 2 of FIG. 3, FIG.

In addition, although not shown, in the case of the flat illumination device 1 having a large screen size, the light guide plate 2 has a structure in which the incident end surface portions 3 are provided at both ends, and the light guide plate 2 has a front surface portion 8 and a back surface from the concept of the present invention. The distance (thickness of the light guide plate 2) to the portion 5 is the smallest (thin) at the incident end face 3 and the distance (thickness) at the center from the incident end face 3 at both ends is maximized (thick). Have a different shape.
That is, although not shown, the flat illumination device 1 has two light sources 10 at both ends of the light guide plate 2, and both end portions of the light guide plate 2 facing the two light sources 10 are incident end surface portions 3, and the thickness is the smallest. The light guide plate 2 becomes thicker toward the center, and the distance between the front surface portion 8 and the back surface portion 5 is maximized at the central portion.

Therefore, the thickness of the light guide plate 2 (distance between the front surface portion 8 and the back surface portion 5) increases from the two incident end surface portions 3 to the opposite side of each incident end surface portion 3 (from each incident end surface portion 3). (Center) The shape is thick (maximum). For this reason, even if the light guide plate 2 has a tapered shape while the incident light from each incident end surface portion 3 travels to the center, there is no light beam that breaks the critical angle α to the center. The first inclined surface portion 6 and the second inclined surface portion when the light beam having repeatedly reflected passes through the center and travels in the direction of the incident end surface portion 3 facing each other (the thickness of the front surface portion 8 and the back surface portion 5 gradually decreases). 7 is totally reflected in the direction of the surface portion 8, and light is emitted from the surface portion 8 substantially vertically.
Therefore, the thickness of the light guide plate 2 becomes thicker from the incident end face portions 3 at both ends toward the center, and the thickness of the center portion is the thickest, so that the mechanical stability and strength of the light guide plate are excellent.

A light source (linear light source, point light source) 10 is a semiconductor light emitting element, and includes an LED, a laser, and the like, and each single color light of RGB (red, green, blue) is provided in the vicinity of the incident end face 3, A unit configured in an array shape in which a plurality of semiconductor light emitting elements composed of RGB (red light emission, green light emission, blue light emission) are combined may be provided on the incident end face portion 3.
In particular, in the case where high luminance is required as the light source 10, a high-luminance light emitting element of a quaternary compound or a compound such as InGaAlP, InGaAlN, or InGaN is used.

  Furthermore, as the light source 10, white light may be obtained using a semiconductor light emitting element and a wavelength conversion material. For example, a wavelength conversion material (YAG system) that is excited by blue light emitted from an InGaAlN-based semiconductor light-emitting element and emits light in yellow, orange, or the like is provided. The light source 10 in which the emission color mixed with the emission color such as orange becomes white may be used.

The light source 10 may use CCFLs (cold cathode fluorescent lamps) when the incident end face portion 3 is large or the light guide plate 2 itself is large. These light sources 10 are linear, and direct light is incident on the incident end face of the light guide plate 2. The light enters the light guide plate 2 from the portion 3, and other light enters the light guide plate 2 through the space between the light source 10 and the reflector while being reflected by a reflector (not shown).
In the case of this linear light source 10, a bright line with high luminance appears in the vicinity of the incident end face 31 in the conventional light guide plate 21, but generation of a bright line by using the light guide plate 2 of the present invention. Can be prevented.

The reflector 11 is made of a thermoplastic resin in which a white material such as titanium oxide is mixed, metal deposition such as aluminum is performed on the thermoplastic resin, or a metal. The reflector 11 covers a portion other than the incident end face portion 3 and the surface portion 8, reflects or irregularly reflects light other than the light from the light source 10 emitted to the surface portion 8 by the light guide plate 2, and enters the light guide plate 2 again. Thus, all the light from the light source 10 is emitted from the surface portion 8.
Further, the reflector 11 used for the anti-incident end face portion 4 and the back surface portion 5 may be provided with a concavo-convex shape, a prism shape, or the like on the reflector 11, and the position to return to the light guide plate 2 again by controlling the concavo-convex shape or the prism shape. Can be adjusted to adjust the luminance, light quantity distribution, emission angle, and the like of the final outgoing light.

  Further, when the reflecting surface has a concave or convex shape or a prism shape, the light source 10 can mix light of three primary colors such as RGB within the light guide plate 2 by reflection by the prism surface. The efficiency of converting the light from the light source 10 into the light emitted from the light guide plate 2 can be improved without wasting it.

Although not shown here, for example, when the directivity of the light source 10 such as CCFL (Cold Cathode Tube) indicates the radial direction, a reflector is provided around the light source 10 (CCFL) and incident on the light guide plate 2. The end surface 3 and the light source 10 are surrounded, the light from the light source 10 is reflected, and the reflected light is incident again on the incident end surface 3 of the light guide plate 2.
The reflector is made of, for example, a white insulating material or a sheet or metal on which a metal such as aluminum is deposited.

A planar illumination device 1e shown in FIG. 17 has a configuration in which the planar illumination device 1 including the light guide plate 2, the light source 10, and the reflector 11 shown in FIG.
Note that the contents described in FIG.

As shown in FIG. 18, the locus of light when the apex angle 15d direction of the prism 15 is directed toward the light guide plate 2 (light deflection portion 8a) on the light deflection portion 8a provided on the surface portion 8 of the light guide plate 2. The light reflected from the anti-incident end surface portion 4 is totally reflected by the first inclined surface portion 6 and the second inclined surface portion 7 of the back surface portion 5. The reflected light Lri1 and the reflected light Lri2 due to the total reflection proceed in the direction of the light deflecting unit 8a, break the critical angle from the light deflecting unit 8a, refract and tilt toward the incident end surface 3 to the light deflecting unit 8a (surface unit 8). The light is emitted to the outside of the light guide plate 2 as outgoing light Lrio1 and outgoing light Lrio2 having a large outgoing angle. The emitted light Lrio1 and the emitted light Lrio2 proceed to one surface 15a of the prism 15 provided on the light deflection unit 8a, are refracted by the first surface 15a of the prism 15, and enter the inside of the prism 15 with the incident light Lpi1 and the incident light Lpi2. And proceeds into the prism 15. Thereafter, the incident light Lpi1 and the incident light Lpi2 are totally reflected by the other surface 15b of the prism 15, and the total reflected light Lpri1 and the total reflected light Lpri2 are substantially perpendicularly emitted from the plane 15c of the prism 15 as the emitted light Lpo1 and the emitted light Lpo2. Can be emitted.
Therefore, the emitted light having a large emission angle emitted from the surface portion 8 can be emitted substantially vertically, and bright emitted light can be obtained.

Furthermore, it shows in FIG. 13 as an example of the light-guide plate 2 and the planar illuminating device 1 of this invention.
The flat illumination device 1b of FIG. 13 includes a directional point light source 10 in the vicinity of one end of the light guide plate 2c, and an incident end surface portion 3 is provided at one end of the light guide plate 2c having a thin rectangular cubic shape. The distance between the front surface portion 8 and the back surface portion 5 (thickness of the light guide plate 2c) is the smallest at the incident end surface portion 3, and the distance between the front end portion 3 is the largest (incident incident) at the end corner 4 at the maximum separation distance. will end surface 3 facing the symmetrical end corners 4), and a rear surface portion 5 first inclined surface portion 6 and sharp second inclined surface 7 gentle facing end corner 4 a direction opposite to the incident end face 3 A staircase shape (radial from the incident end face portion 3) connected alternately and continuously is formed, and a convex light deflection portion 13 c (8 a) having a circular cross section is opposite to the incident end face portion 3 on the surface portion 8. It is provided so as to be directed in the direction of the end corner 4 (radiating from the incident end face portion 3).
The gentle first inclined surface portion 6 and the sharp second inclined surface portion 7 are both mirror surfaces.

  Further, although not shown here, similarly to FIG. 2, the light deflection portion 8 a having a circular cross section on the surface portion is directed toward the end corner 4 opposite to the incident end surface portion 3 (radially from the incident end surface portion 3. The light deflecting portions 8a and the mirror planes 8b may be alternately provided as shown in FIG. 3 and FIG.

Further, the intersection of the light guide plate 2c and the like from both sides side to be connected to a substantially right angle to each other stepped shape to be connected to the incident end face 3 used in Fig. 13, different portions of thicknesses proceeds substantially at right angles from one another aspect, the point The shape that intersects at right angles to each other on the straight line from the light source 10 or one end, or the staircase shape that connects from both side surfaces connected to the incident end surface portion 3 intersects in an arc shape, and which part is always different in thickness Even at the position, the distance from the point light source 10 and one end is constant, and the shape connected from the side surfaces on both ends in an arc shape and the staircase shape connected from both side surfaces connected to the incident end surface 3 intersect each other in a straight line, The shape may be such that the point light source 10 and the straight line from one end are substantially perpendicular and the straight line from the point light source 10 and one end is located at the shortest distance.

  Thus, in the light guide plate 2 and the flat illumination device 1 of the present invention, the thickness of the light guide plate 2 is the thinnest at the position of the incident end surface portion 3, and the thickness of the light guide plate 2 increases as the distance from the incident end surface portion 3 increases. With this configuration, when traveling in the direction from the incident end face portion 3 toward the opposite incident end face portion 4 located on the opposite side of the incident end face portion 3, more total reflection is performed on the mirror surface of each surface of the light guide plate 2. And the total reflection is performed at the non-incident end face portion 4, and then proceeds again in the direction of the incident end face portion 3. Since the thickness of the light guide plate 2 is gradually reduced when proceeding in the direction of the incident end face 3, there are many rays that are deflected by the first inclined surface 6 and break the critical angle at the surface 8, or near the critical angle. The light is condensed by the light deflector 8a together with the taper leak, breaks the critical angle, and exits from the light guide plate 2. The second inclined surface portion 7 has a large angle of deflection due to total reflection even if it is not a light beam close to the critical angle. Therefore, when the total reflection is performed, the incident angle to the surface portion 8 becomes small, and the light deflection portion. The light is condensed by 8a and can be directly emitted from the surface portion 8 (light deflecting portion 8a). In particular, the light totally reflected by the second inclined surface portion 7 can obtain substantially vertical outgoing light.

  Similarly, when the incident end surface portions 3 are provided at both ends of the light guide plate 2, the thickness of the light guide plate 2 is the thinnest at the position of the incident end surface portion 3, and the thickness of the light guide plate 2 is the central portion of the light guide plate 2. It is the structure which becomes the thickest. For this reason, when proceeding from the incident end face portion 3 toward the central portion, only the total reflection occurs at the mirror surface of each surface, and the thickness of the light guide plate 2 gradually increases from the position beyond the central portion toward the opposite incident end face portion 3. Since the thickness of the light guide plate 2 exceeds the central portion of the light guide plate 2, the incident angle is incident on the surface portion 8 that breaks the critical angle α while traveling through the light guide plate 2, and is collected by the light deflection portion 8 a and emitted from the light deflection portion 8 a and uniform. With this, it is possible to obtain high-intensity outgoing light.

  Further, even with a highly directional light source 10, high-luminance outgoing light in the vicinity of the incident end face portion 3 and the shape of the light source 10 such as the semiconductor light-emitting element itself are emitted from the emission surface without reflection (reflection) or luminance spots. . In particular, when the incident end face portions 3 are provided at both ends of the light guide plate 2, the mechanical strength is excellent, and a substantially large exit surface can be secured as much as there is no reflection. Further, even when the light source 10 uses the three primary color lights (RGB) as the white light source 10, since it does not emit near the incident end face 3, the light rays of the respective colors (RGB) are mixed and break the critical angle α while traveling in the forward direction. Sometimes it can be emitted as perfect white light.

  Suitable for backlights from small liquid crystal display devices to backlights for large liquid crystal display devices, etc., especially because it can obtain emitted light with high brightness and no brightness spots or color temperature spots, for example, from mobile products to LCD TVs It is possible to provide a light guide plate and a flat lighting device ranging from a product to a special application.

1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. It is the schematic sectional drawing and locus | trajectory figure of the concept of the light-guide plate concerning this invention. It is a schematic sectional view and a locus diagram of a light guide plate according to the present invention. (A), (b) It is an approximate surface figure and locus figure of a light guide plate concerning the present invention. It is a schematic sectional view and a locus diagram of a light guide plate according to the present invention. It is a schematic back view of the light guide plate according to the present invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. It is the elements on larger scale of the light-guide plate which concerns on this invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. It is a schematic sectional drawing of the plane illuminating device which concerns on this invention. 1 is a schematic perspective view of a flat illumination device according to the present invention. It is the schematic sectional drawing and locus | trajectory figure of the planar illuminating device which concerns on this invention. It is a schematic sectional drawing of the conventional light-guide plate. (A) It is a schematic sectional drawing of the conventional plane illuminating device. (B) It is a schematic plan view of the conventional flat illumination apparatus. It is a schematic sectional drawing of the conventional plane illuminating device.

Explanation of symbols

1, 1b, 1c, 1d, 1e Planar illumination device 2, 2b, 2c Light guide plate 3 Incident end face 4, 4d Anti-incident end face 5 Back face 6, 6d First inclined face 7, 7d Second inclined face 8 Surface portion 8a Light deflection portion 8b Plane 9 Light source (conventional)
10 Light source (point light source, linear light source)
11 Reflector 12, 12b Triangular shape 12c, 12c1 Triangular shape 12c2, 12c3 Triangular shape 12c4, 12c5 Triangular shape 13, 13b, 13c Arc shape 13c1 Arc shape 14 Side surface portion 15 Prism sheet 21 Light guide plate 31 Incident end surface portion 41 Anti-incident end surface Part 61 Front surface part 71 Back surface part Ln1, Ln2 light beam Ln3, Ln4 light beam Lr, Lrr, Lro light beam Lrc, Lrco light beam Lrcm, Lrm light beam Lrs, Lrso, Lrro light beam Lr1, Lr2, Lro2 Lrr light Lrro, Lr2 , Lrio1 rays Lrio2, Lpi1, Lpi2 rays Lpri1, Lpri2 rays Lpo1, Lpo2 rays L01, L02, L03, L04 rays γ refraction angle n refractive index α critical angle

Claims (8)

An incident end face part for guiding light from a linear light source, an anti-incident end face part for reflecting light located on the opposite side of the incident end face part, a front surface part and / or a back surface part for emitting the light, and It has a side surface portion that intersects the front surface portion and the back surface portion, and the rectilinear light incident from the incident end surface portion is reflected on the anti-incident end surface portion without breaking the critical angle while traveling to the anti-incident end surface portion. The thickness of the front surface portion and the back surface portion is minimized in the incident end surface portion so as to break a critical angle while traveling from the counter incident end surface portion to the incident end surface portion. A light guide plate having an outer shape that maximizes the thickness of the front surface portion and the back surface portion,
The back surface portion has a stepped shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing the anti-incident end surface portion are alternately and continuously connected, and the surface portion has a convex shape or / And an optical deflecting portion extending in the direction of the incident end surface portion and the anti-incident end surface portion in a concave shape, and the second inclined surface portion is centered on the same distance position from the two side surface portions, and the center is A light guide plate having an arc shape close to the direction of the incident end surface portion, and the counter incident end surface portion having an arc shape in which the center position of the same distance position swells from the two side surface portions . An incident end face for guiding light from a point light source; an anti-incident end face located at a position other than the incident end face for reflecting the light; and a front surface and / or a back face for emitting the light. While the straight light incident from the end face does not break the critical angle while traveling to the anti-incident end face, the critical angle is reflected by the anti-incident end face and travels from the anti-incident end face to the incident end face. The thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion is increased. A light guide plate having a thin rectangular cubic shape,
The incident end surface portion is provided at one end of the light guide plate, and the distance between the front surface portion and the back surface portion is minimized at the incident end surface portion, and at the end corner of the maximum separation distance from the incident end surface portion. A staircase shape in which the distance between the first and second inclined surface portions is alternately and continuously connected to the back surface portion, and a gentle first inclined surface portion and a sharp second inclined surface portion facing the end corner direction opposite to the incident end surface portion. The surface portion is provided with a light deflection element having a convex or / and concave cross section extending in the direction of the incident end surface , and the second inclined surface portion has the same distance from the two side surface portions. Centering on the position, the center has an arc shape close to the direction of the incident end surface portion, and the anti-incident end surface portion has an arc shape in which the center position of the same distance position swells from the two side surface portions. A light guide plate. 3. The light guide plate according to claim 1, wherein the light deflector has a circular arc shape or a triangular cross section, and an inclined surface is straight or curved, or a top portion of the cross section is notched flat. 3. The light guide plate according to claim 1, wherein the cross section becomes maximum at a maximum distance from the incident end surface portion and becomes smaller as the incident end surface portion is approached. A linear light source;
An incident end face part that guides light from the linear light source, an anti-incident end face part that reflects light and is located on the opposite side of the incident end face part, a surface part that emits the light, and an opposite side of the surface part And a side surface portion that intersects the front surface portion and the back surface portion, and does not break the critical angle while the straight light incident from the incident end surface portion proceeds to the anti-incident end surface portion. The thickness of the front surface portion and the back surface portion is minimized in the incident end surface portion so as to break a critical angle while being reflected by the anti-incident end surface portion and traveling from the anti-incident end surface portion to the incident end surface portion. And the outer shape is such that the thickness of the front surface portion and the back surface portion is maximized at the anti-incident end surface portion, and the back surface portion is a gentle first inclined surface portion facing the anti-incident end surface portion. A staircase shape in which the sharp second inclined surface portions are alternately and continuously connected, Serial surface portion To Rutotomoni provided a light deflecting portion in cross-section extending in the incident end face and the counter-incident end face direction in a convex shape and / or concave shape, the second inclined surface portion has two said side Centered at the same distance position from the center, the center having an arc shape close to the incident end surface portion direction, and the anti-incident end surface portion having an arc shape in which the center position of the same distance position swells from the two side surface portions. and there the light guide plate,
A flat illumination device comprising: a reflector having reflectivity that covers portions other than the incident end surface portion and the surface portion of the light guide plate. The light guide plate further includes a prism sheet at an upper portion on the light exit surface side with an acute angle portion directed toward the light guide plate and a prism portion arranged in parallel with the incident end surface portion and the anti-incident end surface portion. The flat illumination device according to claim 5 . A linear light source;
An incident end face portion that guides light from the linear light source, an opposite incident end face portion that is located on the opposite side of the incident end face portion, reflects light, a front surface portion and a back surface portion that emit the light, and the front surface And a side surface portion that intersects the back surface portion, and straight light incident from the incident end surface portion does not break a critical angle while traveling to the anti-incident end surface portion, and is reflected by the anti-incident end surface portion. The thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion so as to break a critical angle while traveling from the anti-incident end surface portion to the incident end surface portion, and the surface at the anti-incident end surface portion. The outer surface has a shape that maximizes the thickness of the back surface portion and the back surface portion, and the back surface portion has alternating first sloping surface portions and sharp second sloping surface portions that face the counter-incident end surface portion. Consecutively connected staircase shape, the surface has a convex cross section Other / and concave shape on the incident end face and the counter-incident end face direction is provided a light deflecting portion extending Rutotomoni, the second inclined surface portion is from two of the side portions around the same length position The light guide plate having an arc shape in which the center is close to the incident end face portion direction, and the anti-incident end face portion is an arc shape in which the center position of the same distance position swells from the two side face portions ;
A flat illumination device comprising: a reflector having reflectivity that covers a portion other than the incident end surface portion and the emission surface of the light guide plate. A point light source;
An incident end face part that guides light from the point light source, an anti-incident end face part that reflects light and is located at a position other than the incident end face part, and a front surface part and / or a back surface part that emits the light, While the straight light incident from the incident end face does not break the critical angle while traveling to the anti-incident end face, it is reflected by the anti-incident end face and critical while traveling from the anti-incident end face to the incident end face. The thickness of the front surface portion and the back surface portion is minimized at the incident end surface portion so as to break the corner, and the thickness of the front surface portion and the back surface portion is maximized as the distance from the incident end surface portion is increased. A thin plate-like rectangular cube, wherein the incident end face portion is provided at one end of the light guide plate, and the distance between the front surface portion and the back surface portion is minimized at the incident end face portion, and the incident end face portion At the corners of the maximum separation distance from the The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the direction of the end corner opposite to the incident end surface portion are alternately connected, and the surface portion has cross-section convex or / and concave shape on the light deflecting element which extends on the incident end face direction provided Rutotomoni, the second inclined surface portion is centered on the same distance position from the two said side portions, said center Has a circular arc shape close to the incident end face portion direction, and the anti-incident end face portion is a light guide plate having an arc shape in which the center position of the same distance position swells from the two side face portions ,
A flat illumination device comprising: a reflector having reflectivity that covers a portion other than the incident end surface portion and the emission surface of the light guide plate.

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