JP2002133930A - Dual sides formed light guide plate and plane illumination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent appearance of an emission line and a dark line, and to obtain a bright and evenly emitted light. SOLUTION: A light guide plate 2 comprises: an incident end 3 introducing light from the light source; a reflective end part 4 that is located at the opposite side of the incident end 3 and reflects the light; side surface parts 7 that are connected to the incident end 3 and the reflective end part 4; a front surface part 5 that emits light introduced from the incident end 3; a backside part 6 that is located opposite to the surface part 5; a light control part 8 provided on either the surface part 5 or the backside part 6 refracting or reflecting light; and a prism part 9 provided on either the front surface part 5 or the backside part 6 extending from the incident end 3 to the reflective end part 4. The prism part 9 has its ridge cut off diagonally toward the light inlet end part 3 and forms an approximate triangle plane 10. This renders it possible to make the condensing action by the prism small and emit outside the light let in from the incident end 3, while providing reduced diffusion effect to the light reentering the light guide plate from outside, thus preventing appearance of an emission line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided light guide plate and a flat lighting device, and more particularly, to a light control section having an arc shape or the like for performing refraction and reflection on a front surface portion and a rear surface portion. Prevents the appearance of bright lines and dark lines by increasing the area of the prism that extends from the incident end face to the reflective end face, and the ridge of the prism is cut obliquely into a substantially triangular plane toward the incident end face. The present invention also relates to a double-sided formed light guide plate and a plane elucidating device capable of obtaining bright and uniform outgoing light.

[0002]

2. Description of the Related Art A conventional light guide plate is disclosed in, for example,
One disclosed in Japanese Patent No. 40720 is known. This light guide plate has a colored dot printed portion for absorbing light at the upper end of the reflector provided below the back surface of the light guide plate, and the colored dot printed portion is closer to the fluorescent tube. So that the area gradually decreases toward the farther from
Also, the colored dots are made of gray, dark brown, purple, green, etc., and the colored dots are arranged in a plurality of straight lines substantially parallel to the long axis direction of the fluorescent tube, and a plurality of dots arranged in an arbitrary straight line Are arranged almost at the midpoints of the center points of a plurality of dots in a row adjacent to a row of a plurality of dots arranged in an arbitrary straight line.

As a conventional light guide plate, for example, a light guide plate disclosed in Japanese Patent Application Laid-Open No. 8-327828 is known. This light guide plate is provided with a light shielding wall extending along a plane on which a light incident surface is mounted, and a portion where an incident end surface of the light guide plate is connected to the front surface and the back surface is covered with a shielding material. is there.

[0004]

As a conventional light guide plate,
For example, one disclosed in Japanese Patent Application Laid-Open No. 8-240720 has a colored dot printing portion for absorbing light at an upper end of a reflector provided at a lower portion of a back surface of a light guide plate; The printed area of the colored dots may be gradually reduced from the area closer to the fluorescent tube to the area farther from the fluorescent tube, or the colored dots may be gray, dark brown, purple, green, etc. The center points of a plurality of linearly arranged dots arranged in a plurality of straight lines substantially parallel to the axial direction are arranged in a row adjacent to a row of a plurality of linearly arranged dots. In this configuration, the dots are arranged at substantially the middle points of the center points of a plurality of dots.

In a general light guide plate, as shown in FIG. 6, light incident on the light guide plate 2 has a refraction angle γ of 0 ≦ | γ.
It proceeds into the light guide plate 2 within a range satisfying the expression | ≦ sin ⁻¹ (1 / n). For example, the refractive index of an acrylic resin which is a resin material used for a general light guide plate 2 is about n = 1.49. Therefore, at the incident end face portion 3 closest to the light source, the incident angle is 0.
In this case, the light beam travels without being refracted in the direction (reflection end surface portion) opposite to the incident end surface portion 3 (the highest energy value of the light beam), and is incident at a place close to the front surface portion 5 or the back surface portion 6. Is also 0
Incident at an angle close to °.

Further, the maximum angle of incidence is such that the light reflected and scattered by a reflector or the like (not shown) is
The light from the direction to the back surface 6 direction and the light from the back surface 6 direction to the front surface 5 direction have an incident angle of 90 °, and the incident end face 3
Is within the range of about γ = ± 42 °. However, γ = − only in the direction of the back surface 6 near the front surface 5
42 ° only, and γ = only in the front surface 5 direction near the back surface 6
Only + 42 °.

The light incident on the light guide plate 2 within the range of the refraction angle γ = ± 42 ° is transmitted to the light guide plate 2 and the air layer (refractive index n =
At the interface with 1), the critical angle can be expressed by the equation sin α = (1 / n). For example, since the refractive index of an acrylic resin, which is a resin material used for a general light guide plate 2, is about n = 1.49, the critical angle α is about α = 42 °. If there are no grooves, protrusions, or depressions that disturb the light rays on the back surface portion 6, the light inside the light guide plate 2 is totally reflected by the front surface portion 5 and the back surface portion 6 while the surface on the opposite side of the incident end surface portion 3 (the reflection end surface portion). ) Direction.

As described above, light rays within the range of the refraction angle γ = ± 42 ° exist at any position on the incident end face 3, and particularly in the direction of the front face 5 and the rear face 6 near the incident end face 3. The light ray traveling in the direction or the like is a light ray having a refraction angle near γ = 42 °. For example, a light ray having a refraction angle γ = 42 ° near the incident end face part 3 and having a high energy value is the surface part 5 of the incident end face part 3 The light ray L1 incident from a place near the side and the back part 6 side, and incident from a place near the surface part 5 side of the incident end face part 3, is totally reflected by the front part 5 and becomes a light ray L2 on the back part 6. Become, back part 6
Is totally reflected by the dot pattern of the convex portion 40 provided on the light-emitting device, a scattering groove (not shown), etc., and is totally reflected by the back surface portion 6 because the emission angle (reflection angle) β2 is smaller than the incident angle β1 of the light beam L2. The light beam which reaches L <b> 3 and reaches the surface portion 5 breaks the critical angle and exits from the surface portion 5.

Light rays refracted by the projections 40 (not shown) provided on the rear surface portion 6 and the scattering grooves (not shown) and emitted out of the rear surface portion 6 of the light guide plate 2 are reflected by a reflector (not shown). The reflected light is incident on the light guide plate 2 again. When the incident light beam has an emission angle smaller than the incident angle, the light beam breaks the critical angle at the surface portion 5 and is emitted.

Therefore, if there are no grooves, protrusions, or depressions that disturb any light beam on the front surface portion 5 or the rear surface portion 6, total reflection is continued,
If there is a groove, a convex or a concave that disturbs the light beam, it becomes a leak light that breaks the critical angle or a light beam that can leak, but the range condition where the leak light first emerges from the incident end face 3 side is as shown in FIG. As shown, the angle of refraction from the incident end face 3 to the surface 5 is γ.
= + 42 ° or a ray having a refraction angle γ = −42 ° from the incident end surface 3 toward the back surface 6 is obtained by cotγ * L = X, and proceeds to a position X away from the incident end surface 3. Leakage light that breaks the critical angle may be emitted due to the presence of grooves, protrusions or depressions that disturb the light ray at the position.
°, the position of the bright line generated when the thickness of the incident end face 3 of the light guide plate 2 is 2 mm (here, the maximum distance L from the back face 6) is cot (42 °) * 2 = 2.222125, and It appears at a position of about 2.22 mm from the end face.

Therefore, in the light guide plate disclosed in Japanese Patent Application Laid-Open No. 8-240720, the width of the printed portion of the colored dots in the direction perpendicular to the major axis direction of the fluorescent tube is 0.1 mm to 2 mm.
In this case, there is a shift of 0.22125 mm, and the position of the leak light that breaks the critical angle varies depending on the thickness of the light guide plate. The light energy can be absorbed only after the light beam passes through the light guide plate. However, if there is no unevenness or scattering dot pattern, it is present at an odd multiple of X due to total reflection. There is a problem that the exit position of the leak light is affected by the presence of the light.

Here, the distance X from the incident end face 3, the distance L from the front surface 5 and the back surface 6 of the maximum refraction angle γ where the bright line appears, and the refraction angle are γ.

Further, in the case of the wedge-shaped light guide plate 2 in which the inclination between the incident end face portion 3 and the front surface portion 5 or the back surface portion 6 is 6 degrees or more, the back surface portion 6 is a mirror surface, and the presence of unevenness or a scattering dot pattern is present. Without it, π / 2-maximum refraction angle γ (42 °) -6 °
= 42 ° or less, the emission angle becomes smaller than the incident angle, the critical angle is broken, the surface portion 5 becomes a bright line, and there is a problem that a leak light appears at a position matching the above condition.

[0014] In addition, although the description will be somewhat duplicated,
The bright line appearing in the flat illumination device appears parallel to a linear light source such as a fluorescent tube and the width of the bright line is a thin line of about 1/10 mm. There is a problem that if a line is applied with a width similar to the width of the bright line in a part or the like, or if a line is applied for the purpose of alignment with a light guide plate at the time of printing or assembling, a dark line appears more than light absorption. .

Further, for example, an uneven surface or a scattering dot pattern or the like is provided on the front surface portion 5, and a prism pattern extending to the reflection end surface portion 4 at right angles to the incident end surface portion 3 is provided on the rear surface portion 6.
The rays incident from the incident end face 3 and traveling in the direction of the rear face 6 are focused by the prism. The light reflected by the prism at the angle of reflection, enters the prism, travels in the direction of the side surface 7 opposite to the incident side of each prism, reaches the surface portion 5 and exits from the surface portion 5, but the prism is There is a problem that high-intensity light rays emitted from the surface portion 5 appear as bright lines because they are arranged in large numbers along the line 7.

Further, as a conventional light guide plate disclosed in, for example, Japanese Patent Application Laid-Open No. 8-327828, a light shielding wall extending along a plane on which a light incident surface is provided is provided so as to allow the light guide plate to receive light. Since the connection between the end face and the front and back surfaces is covered with a shielding material, the light rays are directly shielded, reducing the amount of light incident on the light guide plate and causing loss of energy from the light source and parts of the shielding material. There are issues such as an increase in points and productivity such as assembly.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide an arc-shaped light control unit for refraction and reflection on a front surface and a back surface of a double-sided light guide plate. A prism extending from the incident end face to the reflective end face on the front surface or the back surface obliquely cuts the ridge of the prism toward the incident end face in a substantially triangular plane so that the area of the bright line or the dark line is increased. An object of the present invention is to provide a double-sided molded light guide plate and a plane elucidating device which can prevent the appearance and obtain bright and uniform emitted light.

[0018]

According to a first aspect of the present invention, there is provided a light guide plate provided with a light control unit for refracting or reflecting light on a front surface or a rear surface and an incident end surface on a front surface or a rear surface. The ridge of the prism portion extending from the prism portion to the reflection end surface portion is cut obliquely in a substantially triangular plane toward the incident end surface portion.

The light guide plate according to the first aspect of the present invention is provided with a light control unit for refraction and reflection on the front surface or the back surface, and a prism portion extending from the incident end surface to the reflection end surface on the front surface or the back surface. Since the ridge of the prism part is cut off obliquely toward the incident end face part, the light-condensing effect of the prism is reduced, and the light is emitted to the outside and the diffusion effect on the light beam from the outside that enters the light guide plate again is small, The appearance of bright lines can be prevented.

Further, in the light guide plate according to the second aspect, the angle between the front surface portion and the rear surface portion of the substantially triangular flat portion is 0.09.
It is characterized by a range of 5 ° to 11.3 °.

In the light guide plate according to the second aspect, the angle between the front surface portion and the rear surface portion of the substantially triangular planar portion is 0.095 ° or more.
Since the angle is in the range of 11.3 °, it is possible to prevent the generation of bright lines with high luminance by the prism regardless of the size and thickness of the light guide plate.

Further, in the light guide plate according to claim 3, the light control portion has a radius of 5 μm to 50 μm and a height or depth of 5 μm.
Arc-shaped convex or arc-shaped concave with a radius of curvature of 10 μm to 100 μm or a maximum projection length of 10 μm
It is characterized in that it is a triangular prism, a quadrangular prism, or a cylinder having a height or depth of 5 μm to 50 μm, which is convex or concave.

According to a third aspect of the present invention, in the light guide plate, the radius of the light control unit is 5 μm to 50 μm, and the height or the depth is 5 μm to 50 μm.
m, arc-shaped convex or arc-shaped concave having a radius of curvature of 10 μm to 100 μm or a maximum projection length of 10 μm to 100
μm and a convex or concave shape of a triangular prism, a square prism and a cylinder having a height or depth of 5 μm to 50 μm, so that a light beam from a light source guided from the incident end face can be emitted in a direction suitable for the purpose. At the same time, the light emitted from the linear light source can be dispersed without being linear.

Further, in the light guide plate according to claim 4, the width of the prism is 5 μm to 1000 μm, and the height or the depth is 5 μm.
１０００1000 μm, and the pitch is 5 μm〜1000 μm.

According to a fourth aspect of the present invention, the light guide plate has a prism width of 5 μm to 1000 μm and a height or depth of 5 μm to 10 μm.
00 μm and the pitch is 5 μm to 1000 μm,
By controlling the width, pitch and height or depth of the prism in accordance with the size of the light guide plate, it is possible to obtain a light beam having a lateral spread with respect to the facing surface.

Further, the flat lighting device according to claim 5 is
A light source, a light incident surface for guiding light from the light source, a reflective surface located opposite to the light incident end, a front surface for emitting light guided from the light incident end, and a rear surface opposite to the surface. And a convex or concave light control unit that has refraction or reflection on the front surface or the back surface and has a side surface portion connected to the incident end surface portion and the reflection end surface portion, and the front surface portion or the rear surface portion from the incident end surface portion. A double-sided molded light guide plate in which the prism portion facing the reflection end surface is cut in a substantially triangular planar shape nearer to the incidence end surface and the ridge of the prism portion is cut off obliquely, a reflector provided at the lower part of the back surface, and a light source And a reflector for reflecting light and re-entering the incident end face portion.

According to a fifth aspect of the present invention, there is provided a flat lighting device, comprising: a light source;
An incident end face for guiding light from the light source, a reflective end face located opposite to the incident end face, a front face for emitting light guided from the incident end face, a back face located opposite to the front face, and an incident end face. A convex or concave light control unit for refraction or reflection is provided on the front surface or the back surface having a side portion connected to the surface and the reflection end surface, and the front end or the reflection end surface is provided on the front surface or the back surface. The two-sided molded light guide plate, in which the prism portion extending toward the substantially triangular flat surface is closer to the incident end face portion, the ridge portion of the prism portion is cut off obliquely, a reflector provided at the lower portion of the back surface portion, and reflects light from the light source. A reflector for re-entering the incident end face is provided, so that the light from the light source guided from the incident end face is controlled in accordance with the size of the light guide plate by controlling the width, pitch and height or depth of the prism. Against the side The prism is made to emit light in a direction suitable for the purpose, and the ridge of the prism is cut obliquely in a substantially triangular plane so that the area of the cut-out portion becomes larger as it is closer to the incident end face, so that the condensing action of the prism is improved. The light emitted from the linear light source can be dispersed without being linearized by reducing the size of the light guide plate, or the light reflected by the reflector has a small diffusion effect on the light from the outside that enters the light guide plate again. Irrespective of the thickness, it is possible to prevent the generation of a bright line of high luminance by the prism.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the present invention provides an arc-shaped or similar light control unit that performs refraction and reflection on the front surface and the back surface of the double-sided molded light guide plate, and has a prism unit that extends from the incident end surface to the reflection end surface on the front surface or the back surface. A light guide plate capable of preventing bright and dark lines from appearing and obtaining a bright and uniform outgoing light by increasing the area of the part where the ridge of the prism is cut obliquely into a substantially triangular plane toward the incident end face. And a flat lighting device.

FIG. 1 is a schematic perspective view of a flat lighting device according to the present invention, FIG. 2 is an enlarged plan view of an incident end face of a light guide plate, and FIG.
FIG. 4 is a schematic diagram of a ray trajectory of a prism portion of the flat lighting device according to the present invention, FIG. 4 is a schematic diagram of a ray trajectory of an incident end face portion of the flat lighting device of the present invention, and FIG. It is a trajectory schematic diagram.

As shown in FIG. 1, a flat lighting device 1 according to the present invention includes a light guide plate 2, a light control unit 8, a reflector 13, and a light source 1.
1 and a reflector 12.

The light guide plate 2 is made of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7, and is provided with an incident end face 3 for guiding light from the light source 10. A reflection end face 4 located on the opposite side to the incident end face 3 for reflecting light into the light guide plate 2; a side face 7 connected to the incident end face 3 and the reflection end face 4; It comprises a part 5 and a back part 6 located on the opposite side of the front part 5.

The light guide plate 2 has a surface portion 5 with a radius of 5 μm.
m to 50 μm, height 5 μm to 50 μm, radius of curvature 1
An arc-shaped convex shape having a diameter of 0 μm to 100 μm or a radius of 5 μm to
An arc-shaped concave light control unit 8 having a height of 50 μm, a height or depth of 5 μm to 50 μm, and a radius of curvature of 10 μm to 100 μm is provided, or a triangular prism having a maximum projection length of 10 μm to 100 μm and a height of 5 μm to 50 μm. Convex shape of prisms and cylinders, maximum projection length 10 μm to 100 μm, depth 5 μm
A concave light control unit 8 of a triangular prism, a quadrangular prism, and a cylinder having a size of ５０50 μm is provided.

As shown in FIG. 2, the light control section 8 has a refraction angle γ = ± 42 ° in the light guide plate from the incident end face portion 3, for example, in an arc-shaped convex shape (however, the light control section 8 is used for the light guide plate 2). The resin material is an acrylic resin having a refractive index of about n = 1.49.) Among the light beams L1 incident on the surface portion 5, the light beam LR1 traveling in the direction of the surface portion 5 is an arc-shaped convex light control applied to the surface portion 5. Proceeding to the part 8, since the incident angle (approximately 20 °) formed by the critical surface 8a with the air layer and the normal of the arc-shaped convex is smaller than the critical angle, it is refracted to the outside (the air layer) and becomes larger than the incident angle. The light beam L0 is emitted at a large emission angle (about 30.6 °).

Although not shown, the light rays traveling in the direction of the back surface 6 are refracted by the prism 9 provided on the back surface 6 at a refraction angle γ = −42 ° and emitted to the outside of the back surface 6 (collectively as a whole). The light reflected by the reflector 13 provided below the light guide plate 2 again passes through the prism 9 and enters the light guide plate 2.

Further, the width of the back surface 6 of the light guide plate 2 is 5
μm to 1000 μm, height or depth of 5 μm to 100
A light beam having a width in the lateral direction with respect to the opposing surface by controlling the width, pitch and height or depth of the prism 9 according to the size of the light guide plate by applying a prism 9 having a pitch of 0 μm and a pitch of 5 μm to 1000 μm. To get

For example, as shown in FIG. 3, the light from the linear light source 11 is refracted at the incident end face portion 3 and the parallel light beam L1 having a refraction angle γ = 0 to -42 ° advances to the back face portion 6 to form the prism 9 and the air layer. Since the incident angle is larger than the critical angle (about 63 °) on the critical surface, the light is reflected and becomes a light beam L12, further proceeds to the opposing surface of the prism 9, and the incident angle is larger than the critical angle on the critical surface between the prism 9 and the air layer. Since the light beam L13 is small (about 16 °), the light beam L13 transmitted through the prism surface reaches the reflector 13 and is reflected at an emission angle equal to the incident angle with respect to the reflector 13, and is reflected by the light beam L1.
4 again travels to the other prism surface, and since the incident angle is smaller than the critical angle at the critical surface between the prism 9 and the air layer, the light beam L15 is refracted and transmitted through the prism 9 again to communicate with the air layer at the prism 9 surface. The incident angle is larger than the critical angle at the critical surface, and the light is reflected and travels toward the surface portion 5 as a light ray L06.

Similarly, since the parallel light beam L11 advances to the back surface portion 6 and the incident angle at the critical surface between the prism 9 and the air layer is larger than the critical angle, it is reflected and becomes a light beam L21 and further advances to the opposite surface of the prism 9. Since the incident angle at the critical surface between the prism 9 and the air layer is smaller than the critical angle, the light beam L22 transmitted through the prism surface reaches the reflector 13 surface and
Reflected at an exit angle equal to the incident angle to
Again travels to the other prism surface, and since the incident angle is smaller than the critical angle at the critical surface between the prism 9 and the air layer, it is refracted and travels toward the surface portion 5 as a light ray L07.

The light rays L06 and L07 are spread by the prism 9 from the incident end face 3 from the linear light source 11 to the reflecting end face 4 so as to spread in the left-right direction of the prism 9 (toward the side face 7 of the light guide plate 2). The parallel light beam traveling toward the surface portion 5 can be spread toward the side portion 7 before reaching the surface portion 5.

As shown in FIG. 4, the prism 9 is larger as it is closer to the incident end face 3 of the light guide plate 2, and has an angle δ with the back face 6 of 0.095 ° to 11.3 °. The ridge is cut diagonally, and the cut surface is roughly triangular
(10a, 10b). This allows
The incident light at the incident end face 3 is light only in the range of the refraction angle γ = ± 42 °, and the parallel light beam LS traveling in the direction of the back surface 6 with the refraction angle γ = 0 to −42 ° is the ridge of the prism 9. Is obliquely cut off, and the angle of incidence is greater than the critical angle (about 65 °) at the critical plane with the air layer in the substantially triangular plane 10. And proceed to the outside of the back surface portion 6, much less the incident end surface portion 3.
No light is emitted to the nearby surface portion 5.

FIG. 5 is a view of the field of view from the incident end face 3 to the substantially triangular plane 10 (a cross-sectional view of two portions of the prism section 9 from the incident end face 3).

The ridge of the prism 9 is cut off obliquely, and the bottom surface of the substantially triangular plane 10 becomes larger as it approaches the incident end face 3 of the light guide plate 2. The parallel light beam LS1 that has traveled in the direction of the back surface 6 at the refraction angle γ = −42 ° reaches one surface of the prism 9 and has a larger incidence angle than the critical angle (about 72 °) at the critical surface with the air layer. The light ray LS11 reflected by one surface proceeds to the bottom surface of the substantially triangular plane 10, where the light ray LS11 is at the critical surface with the air layer and the incident angle is smaller than the critical angle. The transmitted light LS12 is reflected by the reflector 13
The light reaches the surface and is reflected and proceeds in the direction of the surface portion 5, but the light beam LS13
Since the light travels in the direction of the side surface 7 of the light guide plate 2, no bright line is generated on the surface 5 near the incident end face 3.

Similarly, when the bottom surface of the substantially triangular plane 10 is large, the parallel light beam LS2 traveling in the direction of the back surface 6 at the refraction angle γ = −42 ° reaches one surface of the prism 9 and is in contact with the air space. Since the incident angle is larger than the critical angle at the critical plane, the light ray LS21 reflected on one surface proceeds to the bottom surface of the substantially triangular plane 10, where the light ray LS21 is at the critical plane with the air layer and the incident angle is the critical angle. Therefore, the light beam LS22 transmitted through the bottom surface of the substantially triangular planar shape 10 reaches the reflector 13 and is reflected and travels toward the surface 5 so that the reflected light is transmitted to the side surface 7 of the light guide plate 2 like the light beam LS13. Therefore, no bright line occurs on the surface portion 5 near the incident end surface portion 3.

The light rays traveling in the direction of the back surface 6 are:
Although not shown as a whole as shown in FIG. 4, the light beam travels in the direction of the reflection end face 4, and as described further, the reflected light travels in the direction of the side face 7 of the light guide plate 2. There is no occurrence as a bright line.

In FIG. 1, the ridge of the prism 9 continuous with the incident end face 3 and the reflective end face 4 is obliquely cut off to form a substantially triangular plane 10 (10a, 10b). Although the shape is shown, in the case where all the light rays that have entered the light guide plate 2 do not effectively exit to the surface section 5 and many light rays reach the reflection end face section 4 direction, only the incident end face section 3 side is used. May be cut obliquely to form a substantially triangular plane 10 (10a). When the light guide plate is long, or when the light source is disposed opposite to both end surfaces (in the case of FIG. 1, the incident end surface portion 3 and the reflective end surface portion 4 in FIG. 1), the prism portion as shown in FIG. Preferably, the ridges at both ends of 9 are cut obliquely to form substantially triangular planar shapes 10a and 10b.

The light source 11 has a linear shape such as a CFL (cold shadow tube). Direct light enters the light guide plate 2 from the incident end face 5 of the light guide plate 2, and other light is reflected by the reflector 12. The light enters the light guide plate 2 through the space between the light source 11 and the reflector 13.

The reflector 12 is made of a sheet or metal on which a white insulating material or a metal such as aluminum is deposited, and surrounds the incident end face 5 of the light guide plate 2 and the light source 11. The light is reflected, and the reflected light is incident again on the incident end face 5 of the light guide plate 2.

The reflector 13 is made of a sheet in which a white material such as titanium oxide is mixed in a thermoplastic resin or a sheet of a thermoplastic resin, which is formed by depositing a metal such as aluminum, or a sheet in which a metal foil is laminated. And the light from the light source 11 is reflected by the light guide plate 2 to reflect the light other than the light emitted from the light source plate 11 to the light guide plate 2, and is again incident on the light guide plate 2. Is emitted from the surface portion 5.

As described above, the double-sided light guide plate and the flat lighting device of the present invention have a radius of 5 μm to 50 μm and a height or depth of 5 μm to 5 μm for refraction and reflection on the front and back surfaces of the double-sided light guide plate. 50 μm, radius of curvature 10 μm to 100
μm arc-shaped convex or arc-shaped concave or maximum projection length of 10 μm to 100 μm, height or depth of 5 μm to
A 50 μm light control unit such as a triangular prism, a quadrangular prism, and a cylindrical convex or concave arc-shaped light control unit is provided, and the width of the prism extending from the incident end surface to the reflection end surface on the front surface or the rear surface is 5 μm to 1000 μm, and the height is 5 μm to 1000 μm. Or 5 μm in depth
A prism having a pitch of 5 μm to 1000 μm and an angle of 0.095 ° to 11.3 ° with a ridge of the prism and a rear surface facing the incident end face is cut obliquely into a substantially triangular plane. By increasing the area of the portion, the appearance of bright lines and dark lines is prevented, and bright and uniform emitted light is obtained.

[0049]

As described above, the light guide plate according to the first aspect is provided with a light control section for performing refraction and reflection on the front surface or the back surface, and from the incident end surface to the reflection end surface on the front surface or the back surface. Since the extending prism part is cut obliquely toward the incident end face part in a substantially triangular planar shape,
The light condensing effect of the prism is reduced, and the light is emitted to the outside. The diffusion effect on the light from the outside that is incident on the light guide plate again is small, and the appearance of bright lines can be prevented.

Further, in the light guide plate according to the second aspect, the angle between the front surface portion and the rear surface portion of the substantially triangular flat portion is 0.09.
Since the angle is in the range of 5 ° to 11.3 °, it is possible to prevent the generation of high-luminance bright lines by the prism regardless of the size and thickness of the light guide plate, and to easily design any light guide plate or flat lighting device. it can.

Further, in the light guide plate according to the third aspect, the radius of the light control section is 5 μm to 50 μm, and the height or the depth is 5 μm.
Arc-shaped convex or arc-shaped concave with a radius of curvature of 10 μm to 100 μm or a maximum projection length of 10 μm
１００100 μm, and the height or depth is 5 μm to 50 μm.Because of the convex or concave shape of the triangular prism, the square prism and the cylinder, the light from the light source guided from the incident end face can be emitted in a direction suitable for the purpose. As a result, the light emitted from the linear light source can be dispersed without being linearized, and a bright light guide plate that is easy to see can be obtained.

Further, in the light guide plate according to the fourth aspect, the width of the prism is 5 μm to 1000 μm, and the height or the depth is 5 μm.
Since the pitch is 5 μm to 1000 μm and the width, pitch and height or depth of the prism are controlled in accordance with the size of the light guide plate, a light beam having a lateral spread with respect to the facing surface is obtained. Therefore, by controlling the light beam in the direction of the reflection end face or the direction of the incidence end face by the light control section, it is possible to obtain outgoing light having a wide viewing angle in the entire light guide plate.

Further, in the flat lighting device according to the fifth aspect, the light source, the light incident from the light source, and the light guided from the reflecting end surface and the light incident end surface opposite to the light incident end surface. A convex or concave type that has a front surface portion that emits light, a back surface portion opposite to the front surface portion, and a side surface portion connected to the incident end surface portion and the reflective end surface portion and performs refraction or reflection on the front surface portion or the back surface portion. A double-sided light guide plate in which a light control unit is provided and a prism extending from the incident end surface to the reflection end surface on the front surface or the rear surface is cut into a substantially triangular plane obliquely with a ridge of the prism facing the incident end surface. And a reflector provided at the lower portion of the back surface portion, and a reflector that reflects the light of the light source and makes it incident again on the incident end surface portion, so that the light from the light source guided from the incident end surface portion depends on the size of the light guide plate. The width of the prism,
By controlling the pitch and the height or depth, the side surface is expanded in the side direction with respect to the opposing surface to emit in the direction suitable for the purpose, and the ridge of the prism is cut obliquely in a substantially triangular plane shape and the incident end surface The closer it is, the larger the area of the cut-out part is, the smaller the light condensing action by the prism is to disperse the emitted light from the linear light source without making it linear, and the light reflected by the reflector is incident on the light guide plate again Since the diffusion effect on external light rays is small, it is possible to prevent the generation of bright lines by the prism regardless of the size and thickness of the light guide plate. It can handle various objects such as monitors and monitors that require a wide viewing angle.

[Brief description of the drawings]

FIG. 1 is a schematic perspective horizontal view of a flat lighting device according to the present invention.

FIG. 2 is an enlarged plan view of an incident end face portion of the flat lighting device according to the present invention.

FIG. 3 is a schematic view of a ray trajectory of a prism portion of the flat illumination device according to the present invention.

FIG. 4 is a schematic view of a ray trajectory of an incident end face of the flat illumination device according to the present invention.

FIG. 5 is a schematic view of a ray trajectory of a prism portion of the flat illumination device according to the present invention.

FIG. 6 is a schematic view of a ray trajectory of a conventional light guide plate.

FIG. 7 is a schematic view of a ray trajectory of a conventional light guide plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Planar illuminating device, 2 ... Double-sided molded light guide plate, 3 ... Incident end surface part, 4 ... Reflection end surface part, 5 ... Front surface part, 6 ... Back surface part, 7 ... Side surface part, 8 ... Light control part, 8a ... Critical surface , 9 ... prism part,
10 (10a, 10b): substantially triangular planar shape; 11: light source;
12: reflector, 13: reflector, n: refractive index, γ: refraction angle, δ: angle formed with the back surface, L1, LR1, L0, L
11, L06, L07, L21, L22, L15, L2
3, L12, L13, L14, L15, LS0, LS,
LS1, LS2, LS11, LS12, LS13, LS
21, LS22, L2, L3 ... light rays, L ... thickness of the light guide plate.
40: dot pattern of projection, β1: incidence angle, β2: emission angle.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) G02F 1/13357 F21Y 103: 00 // F21Y 103: 00 G02F 1/1335 530 F term (Reference) 2H038 AA55 BA06 2H042 CA01 CA12 CA17 DA02 DA06 DA11 DE04 2H091 FA21Z FA23Z FB02 FB08 KA10 LA11 LA18

Claims (5)

[Claims] An incident end face for guiding light from a light source, a reflecting end face located on the opposite side of the incident end face for reflecting light,
A side surface connected to the incident end face and the reflective end face, and a surface that emits light guided from the incident end face,
In the light guide plate having a back surface portion located on the opposite side of the front surface portion, a light control unit that performs refraction or reflection is provided on the front surface portion or the back surface portion, and the light incident portion on the front surface portion or the back surface portion. A double-sided molded light guide plate, wherein a ridge portion of the prism portion is cut obliquely toward the incident end surface portion of the prism portion extending to the reflection end surface portion in a substantially triangular plane shape. 2. An angle between the substantially triangular planar portion and the front surface portion or the rear surface portion is 0.095 ° to 11.3.
2. The double-sided light guide plate according to claim 1, wherein the angle is in a range of degrees. 3. The light control section has a radius of 5 μm to 50 μm.
m, height or depth 5 μm to 50 μm, radius of curvature 1
It is characterized in that it is a convex or concave shape of a triangular prism, a quadrangular prism and a cylinder having a convex shape of an arc of 0 to 100 μm or a concave shape of an arc or a maximum projection length of 10 to 100 μm and a height or depth of 5 to 50 μm. The double-sided molded light guide plate according to claim 1. 4. The prism has a width of 5 μm to 1000 μm.
2. The double-sided light guide plate according to claim 1, wherein the light guide plate has a height of 5 [mu] m to 1000 [mu] m and a pitch of 5 [mu] m to 1000 [mu] m. 5. A light source, an incident end face for guiding light from the light source, a reflective end face opposite to the incident end face, a surface for emitting light guided from the incident end face, and the surface. A convex or concave light control unit that has a back surface located on the opposite side to the incident end surface and a side surface connected to the reflective end surface and performs refraction and reflection on the front surface or the back surface. A double-sided molding in which a prism portion extending from the incident end surface portion to the reflection end surface portion on the front surface portion or the rear surface portion is obliquely cut in a substantially triangular planar shape toward the incident end surface portion. A flat lighting device comprising: a light guide plate; a reflector provided at a lower portion of the back surface; and a reflector that reflects light from the light source and causes the light to enter the incident end surface again.