JP2010044922A - Plane light source element and light control member used for this as well as image display using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high luminance uniformity and color uniformity in a front face direction without rigorous positioning of a light source with other members, in a plane light source element of a down-light type with color reproductivity enhanced with the use of point light sources of an LED or the like. <P>SOLUTION: With the use of a light control member (2) equipped with a sheet having a plurality of convex parts (21), of the convex part, one of normals of the X-Y plane which is parallel to an X-axis and a Y-axis crossing the X-axis is to be a Z-axis direction, a cross-section shape in an optional plane parallel to the X-Y plane is made to be constant, and a cross-section shape in an optional plane parallel to the Y-Z plane is made to be constant, and also, a light beam direction is controlled two-dimensionally and by all surfaces of the light control member (2). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface light source element having a plurality of point light sources, a sheet-like light control member provided in the surface light source element, and an image display apparatus using the same, and particularly requires a large size, high luminance and luminance uniformity. In particular, the present invention relates to a direct-type surface light source element used in an illumination signage device, a liquid crystal display device, and the like, a light control member included in the surface light source element, and an image display device using the light control member.

  As a surface light source for illuminating a transmissive liquid crystal display, a lighting signboard, and the like from the back, there are an edge light method and a direct light method. The edge light method is a method of taking out light from a light source arranged on the end face of the light guide plate in a front direction from the main surface orthogonal to the end face by the light guide plate, and the direct method is arranging a plurality of light sources on the back of the device, In this method, light is incident on a diffuser plate, the light is made uniform by the diffuser plate, and the light is extracted to an exit surface opposite to the incident surface (see, for example, Patent Document 1).

There is an increasing demand for large-sized image display devices in television and personal computer monitors, and direct light sources that are advantageous in terms of brightness improvement and uniformity are the mainstream for surface light source elements used in large-sized image display devices. It has become.
The direct-type surface light source element includes a light source, a reflection plate, a diffusion plate, a lens sheet, and the like. The reflection plate has a function of reflecting light emitted from the light source to the back side in the front direction. The diffusion plate and the lens sheet have a function of diffusing light to reduce the image of the light source, and a function of converting the diffused light into appropriate directivity.

  As a light source, a fluorescent lamp, which is a linear light source, has been used, but there are problems such as poor color reproducibility and load on the environment due to the use of mercury. Therefore, it has been proposed that a point light source such as a light emitting diode (LED) that does not use mercury is arranged in a plane and used as a planar light source (for example, Patent Document 2, Non-patent). Reference 1).

  However, when the point light source is arranged in a plane, the contrast between the light source images is generated two-dimensionally. Furthermore, the light emission of the LED has a strong directivity, and it is more difficult to obtain high luminance uniformity than when a linear light source is used. In addition, when using LEDs of each color such as red, blue, and green in order to widen the color coordinates, it is difficult to obtain color uniformity. It is possible to increase brightness uniformity and color uniformity by increasing the fine particles of the diffusion plate, but light absorption and light emitted in unnecessary directions increase, and light use efficiency decreases. Therefore, it is not preferable from the viewpoint of energy saving.

  A technique for providing two lenticular lens shapes has been disclosed in order to improve the light utilization efficiency and obtain high brightness uniformity (see, for example, Patent Document 3). However, since two lenses, a lenticular lens for reducing the light source image in the X-axis direction and a lenticular lens for reducing the light source image in the Y-axis direction, are used, the number of members increases and the productivity is increased. In addition, since the lenticular lens arranged on the light source side affects other than the target direction, it is difficult to reduce the two-dimensional light source image. If the luminance and / or color is not uniform in one of the X-axis direction and the Y-axis direction, a striped luminance distribution and color distribution result, and the screen quality deteriorates.

Japanese Patent Laid-Open No. 2-17 Japanese Patent Laid-Open No. 7-191311 JP 2007-12517 A Nikkei Business Publications, Inc. Flat-Panel Display 2004 Practice p170

  Therefore, in the present invention, for example, a direct-type surface light source element used in an image display device or the like, which uses a point light source such as an LED, enables high color reproducibility, high brightness, and uniform brightness. An object of the present invention is to provide a surface light source element capable of realizing energy saving because of high color uniformity and high light utilization efficiency, a sheet-like light control member provided in the surface light source element, and an image display device using the surface light source member.

That is, the present invention provides the following means in order to solve the above problems.
The first invention of the present application is
One of the normals of the XY plane parallel to the X axis and the Y axis orthogonal to the X axis is defined as the Z axis direction.
at least,
A light emitting surface parallel to the XY plane, a plurality of point light sources, and a sheet-like or film-like light control member,
The plurality of point light sources are arranged in a virtual plane parallel to the XY plane,
The light control member is arranged in parallel to the XY plane and on the Z-axis direction side of the plurality of point light sources,
The light-emitting surface is a surface light source element disposed on the Z-axis direction side of the light control member,
The light control member has a plurality of convex portions on the surface from which light is emitted mainly,
The plurality of convex portions,
The cross-sectional shape in an arbitrary plane parallel to the XZ plane is constant,
and,
A surface light source element having a constant cross-sectional shape in an arbitrary plane parallel to the YZ plane.

The second invention of the present application is the surface light source element of the first invention,
The surface light source element, wherein the plurality of point light sources are periodically arranged in the X-axis direction and periodically arranged in the Y-axis direction.

The third invention of the present application is the surface light source element of the second or third invention,
The contour line of the cross-sectional shape in a plane parallel to the XZ plane of the plurality of convex portions consists of a part of a curve made of an ellipse, a parabola, or a polynomial,
and,
The surface light source element is characterized in that an outline of a cross-sectional shape in a plane parallel to the YZ plane is formed of a part of a curve made of an ellipse, a parabola, or a polynomial.

Moreover, 4th invention of this application is any one of said surface light source elements,
The ratio b ₁ / a ₁ of the contour line width a ₁ and the contour line height b ₁ in a plane parallel to the XZ plane of the plurality of convex portions is 0.28 to 0.65. Yes,
and,
A surface having a ratio b ₂ / a _{2 of} a contour line width a ₂ and a contour line height b ₂ in a plane parallel to the YZ plane is 0.28 to 0.65. It is a light source element.

Moreover, 4th invention of this application is any one of said surface light source elements,
The maximum inclination angle θ1 of the contour line of the cross-sectional shape in a plane parallel to the XZ plane of the plurality of convex portions is 50 degrees to 82 degrees,
and,
The surface light source element is characterized in that the maximum inclination angle θ2 of the contour line of the cross-sectional shape in a plane parallel to the YZ plane is 50 degrees to 82 degrees.

  Moreover, 6th invention of this application is a sheet-like or film-like light control member with which one of said surface light source elements is provided.

  The seventh invention of the present application is an image display device characterized in that a transmissive display device is arranged on the light emitting surface of the surface light source element of the present invention.

  The effects of the present invention will be described in detail below.

  The surface light source element of the present invention has a high color reproducibility by using a point light source, a diffuser plate in which fine particles for diffusing light are dispersed, a sheet having a plurality of convex portions, or High luminance uniformity and color uniformity are obtained by replacing the film-like light control member in two dimensions to control the direction of the light beam. In the present invention, it is not only advantageous for the size change by giving a uniform property that similarly controls the direction in which the incident light is emitted at all points on the incident surface of the light control member, It is not necessary to align the position. Furthermore, the combined functions of the light control member, such as brightness uniformity and brightness enhancement effect, make it possible to eliminate or reduce the use of other functional optical films, which is advantageous for productivity and thickness reduction. In addition, by disposing a transmissive display device on the light emitting surface of the surface light source element, a high-quality image display device having high color reproducibility and high luminance uniformity and color uniformity can be obtained. .

  A surface light source element provided by the present invention is a surface light source element having a light emitting surface parallel to an XY plane parallel to an X axis and a Y axis orthogonal to the X axis. -It has a plurality of point light sources arranged in a virtual plane parallel to the Y plane, and one sheet-like or film-like light control member. Therefore, high brightness uniformity and color uniformity can be obtained.

  The light from the point light source is incident on the light control member at a small angle from the Z axis immediately above the point light source, and is incident on the light control member at a large angle from the Z axis at a position away from the point light source. It is possible to reduce the image of the point light source by directing the light ray direction of the light incident on the light control member in the Z-axis direction by a convex portion provided on the exit surface of the light control member.

  FIG. 2 shows the principle of controlling the light beam direction in the light control member of the present invention. A light beam incident from a position away from the point light source is refracted on the incident surface and the output surface of the light control member, and the direction thereof changes. At this time, by providing a convex portion on the exit surface, the light is refracted on the slope of the convex portion, and the angle from the Z-axis direction is small, and the light is deflected and emitted in the front direction.

  In the present invention, the convex portions can control the light beams in the X-axis direction and the Y-axis direction on all surfaces of the light control member, and the light source image can be erased two-dimensionally. Furthermore, by making the cross-sectional shape in an arbitrary plane parallel to the XZ plane of the convex portion constant and making the cross-sectional shape in an arbitrary plane parallel to the YZ plane constant, all the light control members Light can be controlled along the X-axis direction and the Y-axis direction at the position, and high brightness uniformity can be obtained by efficiently deflecting light in the vicinity of the Z-axis direction.

  In addition, when many types of point light sources that emit light of a specific color are used, high color uniformity is achieved by making the distribution constant for each color.

  The surface light source element of the present invention has a light beam along the X-axis direction and the Y-axis direction even when the arrangement of the point light sources is distributed along the two-dimensional direction (X-axis direction and Y-axis direction). By using a light control member with a convex portion that can control the direction, light is controlled two-dimensionally with a single light control member, and both good brightness uniformity and color uniformity are achieved. realizable. In addition, by obtaining high luminance uniformity, the thickness can be easily reduced and the productivity can be improved. Further, since light can be deflected in the Z-axis direction, the luminance in the Z-axis direction is improved, and a surface light source element with higher quality can be obtained.

The shape of the plurality of protrusions having a constant cross-sectional shape in an arbitrary plane parallel to the XZ plane and a constant cross-sectional shape in an arbitrary plane parallel to the YZ plane is, for example, convex The coordinates of the X-axis, Y-axis, and Z-axis directions of the part are respectively x, y, and z,
z (x, y) = f (x) + g (y) (1)
It can be expressed as. Here, f (x) and g (y) are functions expressing contour lines of a cross-sectional shape in the YZ plane and XZ plane of the convex portions, respectively.

  According to the second aspect of the present invention, the same luminance and color can be realized on the light emitting surface of the surface light source element by periodically arranging a plurality of point light sources in the X-axis direction and the Y-axis direction. Further, by periodically arranging the point light sources, high luminance uniformity and color uniformity can be obtained on all the light emitting surfaces of the surface light source element.

  According to the third invention of the present application, the contour of the cross section in the plane parallel to the XZ plane and the contour of the cross section in the plane parallel to the YZ plane of the convex portion of the light control member are smoothly curved. By doing so, it is possible to spread the light from the point light source continuously and smoothly, and a smooth and uniform luminance and color distribution can be realized. Further, by forming the convex portion with a smooth curved surface, high productivity and durability such as good moldability and less damage are realized.

The fourth invention of the present application relates to the ratio b ₁ / a ₁ of the width of the contour line and the height of the contour line in the plane parallel to the XZ plane of the convex portion of the light control member, and the YZ plane. By reducing the ratio b ₂ / a ₂ between the width of the contour line of the cross-sectional shape and the height of the contour line in a plane parallel to the plane from 0.28 to 0.65, the light source image is effectively reduced, and the luminance and color It is possible to increase the uniformity. Moreover, since the ratio of the width and height of the cross-sectional shape of the convex portion is within a specific range, the moldability is good and high productivity is realized. Here, the width and height of the contour line in the cross-sectional shape of the convex portion do not depend on the height at which the entire contour line exists, and are, for example, as shown in FIG.

The fifth invention of the present application is the maximum inclination angle θ ₁ of the contour line of the cross-sectional shape in the plane parallel to the XZ plane, and the contour of the cross-sectional shape in the plane parallel to the YZ plane. By making the maximum inclination angle θ _{2 of the} line 50 to 82 degrees, the light is incident on the light control member obliquely with respect to the Z-axis direction at a position away from the point light source along the X-axis direction and the Y-axis direction. Therefore, it is possible to direct a large amount of the light to the vicinity of the front, reduce the light source image, and realize high brightness uniformity, color uniformity, and high brightness. Furthermore, when the maximum inclination angle of the cross-sectional shape in the XZ plane and the YZ plane of the convex portion is 50 to 82 degrees, the moldability becomes good and high productivity can be realized.

  A sixth invention of the present application is a sheet-like or film-like light control member having a light control means for controlling a light beam direction along the X-axis or Y-axis, which is included in any of the surface light source elements described above. By using the light control member, it is possible to control the distribution of light emitted from the point light source in the front direction and to obtain a surface light source element that realizes high luminance uniformity and high color uniformity.

  A seventh invention of the present application is an image display device configured by disposing a transmissive display device on the light emitting surface of any one of the above surface light source elements. The surface light source element is a surface light source element that has high luminance uniformity and color uniformity in the front direction. By arranging a transmissive display device on the light emitting surface, color reproducibility is improved. Since the luminance and color uniformity are high, a high-quality image can be realized. Here, the image display device of the present invention is a display module in which a surface light source element and a display element are combined, and further a device having at least an image display function using the display module, such as a television, a personal computer monitor, an advertisement signboard, etc. including.

  An example of the best mode of the present invention is shown in FIG. One of the normal lines of the XY plane parallel to the X axis and the Y axis orthogonal to the X axis is defined as the Z axis direction, and at least a light emitting surface parallel to the XY plane, a plurality of point light sources, A surface light source element including a light control member having a convex portion having a constant cross-sectional shape in the −Z plane and a constant cross-sectional shape in the YZ plane.

  Although there is no restriction | limiting in particular as a point light source of this invention, LED etc. can be used. Examples of the LED include a white LED and LEDs of each color such as red, blue, and green. Only white is used, and each color LED is periodically arranged.

  When the point light sources are arranged periodically, a plurality of point light sources having the same color may be arranged in one cycle. As a result, it is possible to adjust the color and brightness on the light emitting surface of the surface light source element, and also to reduce the uniformity of brightness due to the variation in brightness among the point light sources in the same color. It is possible to reduce the uniformity degradation.

  A point light source of a color other than a green point light source, a red point light source, or a blue point light source may be used as the point light source. By using a point light source of another color, it is possible to obtain higher luminance and higher color reproducibility.

  In the case where the point light sources are arranged periodically, various forms are conceivable as the arrangement of the point light sources within one cycle. An example that can be used in the present invention is shown in the figure. FIG. 7 shows an example in which three color point light sources are arranged in a triangle. FIG. 8 shows an example in which four color point light sources are arranged in a square shape. FIG. 9 shows an example in which three color point light sources are arranged in a straight line.

  Although various forms can be considered as the arrangement of the point light source, an example that can be used in the present invention is shown in the drawing. FIG. 4 shows an example in which each point light source is arranged in a rectangular shape. FIG. 5 shows an example in which the point light sources are arranged in a staggered manner. In FIG. 5, there are four nearest point light sources adjacent to a certain point light source, and each is in an oblique 45 degree direction. FIG. 6 is also an example in which the point light sources are arranged in a staggered manner. In FIG. 6, there are six closest point light sources adjacent to a certain point light source, and form a regular hexagon.

  The shorter the distance between the adjacent point light sources and the point light source along the X-axis direction and the distance between the adjacent point light sources and the point light source along the Y-axis direction, the more uniform the luminance and the color. It is desirable because of its good characteristics and high luminance. However, if the period is too short, the number of point light sources increases, resulting in an increase in power consumption and a problem of heat generation. The distance between adjacent point light sources and point light sources along the X-axis direction and the Y-axis direction is preferably 7 mm to 70 mm. More desirably, the thickness is 15 mm to 50 mm.

  A longer distance between the point light source and the light control member is desirable because of high brightness uniformity and color uniformity. However, if the length is too long, the thickness of the entire apparatus increases, which is not preferable. The distance between the point light source and the light control member is preferably 5 mm to 50 mm. More desirably, the thickness is 10 mm to 30 mm.

When the ratio b ₁ / a ₁ of the contour line width to the contour line height in the plane parallel to the XZ plane of the convex portion of the light control member is smaller than 0.28, XZ Light incident from a point light source at an angle with respect to the Z-axis direction on the plane cannot be efficiently deflected in the front direction, and it is difficult to obtain luminance uniformity and color uniformity. . Similarly, even when the ratio b ₂ / a ₂ between the width of the contour line and the height of the contour line in a plane parallel to the YZ plane is smaller than 0.28, the luminance uniformity and the color It is difficult to obtain uniformity. On the other hand, when b ₁ / a ₁ and b ₂ / a ₂ are larger than 0.65, it is difficult to form the convex portion, and the productivity is lowered. When b ₁ / a ₁ and b ₂ / a ₂ are 0.28 to 0.65, it is possible to efficiently emit light from a point light source in the vicinity of the Z-axis direction, and to improve productivity. A high surface light source element is obtained. b ₁ / a ₁ and b ₂ / a ₂ are more preferably 0.30 to 0.62, and further preferably 0.32 to 0.59.

The convex portion in the light control member, X-Z plane and the maximum inclination angle theta ₁ of the cross-sectional shape of the contour line in a plane parallel, the maximum inclination angle theta ₂ and is excessively cross-sectional shape of the contour lines in the Y-Z plane If it is small, only the light incident on the light control member from the point light source at a small angle with respect to the Z-axis direction is emitted in the front direction, so that it is emitted near the Z-axis direction at a position away from the point light source. Light may be reduced and it may be difficult to achieve brightness uniformity and color uniformity. On the other hand, if the maximum inclination angle is excessively large, it is possible to deflect light incident on the light control member at a large angle with respect to the Z-axis direction from the point light source, but it becomes more difficult to mold, Productivity decreases. When θ ₁ and θ ₂ are 50 to 82 degrees, it is possible to obtain a surface light source element with high luminance uniformity and color uniformity, good moldability, and high productivity. θ ₁ and θ ₂ are more preferably 53 to 75 degrees, and still more preferably 60 to 72 degrees.

  Although it is desirable that the thickness of the light control member is thin, in the surface light source element of the present invention which is a direct type, since a space is provided between the light source and the light control member, the light control disposed closest to the light source side It is desirable that the member has a thickness that does not cause bending or deformation. Although the light control member varies depending on the size of the surface light source element, the thickness is preferably 0.5 mm to 5 mm. If it is thinner than this, the light control member will be bent or deformed, the point light source will come into contact with the light control member, and the appearance quality will deteriorate. On the other hand, if it is thicker than this, the surface light source element becomes thick and the weight increases. Further, it is desirably 1 mm to 4 mm, and more preferably 1.5 mm to 2.5 mm. In this range, the strength is maintained, and furthermore, an increase in manufacturing cost due to an increase in the amount of the base material used per main surface area can be suppressed.

The width a ₁ of the contour line of the cross-sectional shape in the plane parallel to the XZ plane and the width a ₂ of the contour line of the cross-sectional shape in the YZ plane are preferably 10 μm to 500 μm. If it is larger than 500 μm, the pattern itself is visually recognized from the exit surface, and the appearance quality is lowered. On the other hand, if it is smaller than 10 μm, it is colored by the diffraction phenomenon and the appearance quality is lowered. More preferably, it is 20 μm to 400 μm, and further desirably 40 μm to 300 μm. Within this range, the pattern itself is difficult to observe, and the production is facilitated and the productivity is improved. Further, in the image display device in which the transmissive display device is provided on the light emitting surface of the surface light source element of the present invention, a ₁ and a ₂ are in the range of 1/100 to 1 / 1.5 of the pixel pitch of the transmissive display device. It is desirable to be in If it is larger than this, interference fringes with the pixel pitch are generated and the appearance quality is lowered.

  Although there is no restriction | limiting in particular as a manufacturing method of a light control member, Extrusion molding, injection molding, 2P (Photo Polymerization) shaping | molding which uses an ultraviolet curable resin can be raised, but the magnitude | size of a convex part, the shape of a convex part, mass production A suitable molding method may be selected in consideration of the appropriateness. When the main surface is large, extrusion molding is suitable.

  As a material of the light control member, any ordinary optical transparent material can be used. For example, methacrylic resin, polystyrene resin, polycarbonate resin, cycloolefin resin, methacryl-styrene copolymer resin, cycloolefin-alkene copolymer resin and the like can be mentioned.

  In order to use more light, a reflector or the like may be used on the back surface of the light source. By using the reflector, light emitted from the light source in the back direction, light emitted in the back direction by the light control member can be directed in the Z-axis direction, more light can be used, and high brightness can be obtained. Is possible.

  The reflection plate has a function of reflecting light coming from the light source to the back side in the front direction. A reflectance of 95% or more is desirable because of high light utilization efficiency. Examples of the material of the reflecting plate include metal foils such as aluminum, silver, and stainless steel, white coating, and foamed PET resin. In order to increase the light utilization efficiency, it is desirable that the material has a high reflectance. This includes silver, foamed PET, and the like. In order to improve the uniformity of brightness and the uniformity of color, it is desirable that the material be diffusely reflected. This includes foamed PET and the like.

  Further, in order to further improve the uniformity of brightness and the uniformity of color, the light control member of the present invention may be provided with a light diffusion means. As the light diffusing means, a method of providing random irregularities such as embossing and embossing on the main surface of the light control member, a method of providing fine particles that diffuse a small amount of light inside the structure, and a diffusion sheet as the incident surface of the light control member The method of providing in the side and / or the output surface side, or the method which combined these is mentioned.

  Random irregularities can be realized by applying a solution in which fine particles are dispersed to the main surface by spraying, molding by extrusion of a resin in which fine particles are dispersed, and transferring from a mold having irregularities.

  When fine particles for diffusing light are provided inside the structure, the concentration of the fine particles can be kept lower than that of a normal diffusion plate. Any material used for a diffusion plate or the like can be preferably used. The preferred concentration of fine particles varies depending on the material, and examples thereof include dispersing 0.4% by weight of siloxane polymer particles in a methyl methacrylate-styrene copolymer.

  In addition, a diffusion sheet may be used to obtain more uniform brightness and color uniformity, and a prism sheet, a deflection separation film, or the like may be used to obtain high frontal brightness.

  In addition, a transparent support substrate made of resin, glass, or the like may be provided on the light source side of the light control member. By disposing the support substrate, it is possible to prevent bending or deformation even if the light control member is thinned from 0.1 mm to 1 mm, for example. By reducing the thickness of the light control member, molding by extrusion molding or the like is further facilitated, and productivity is improved. In addition, it becomes easy to support the light control member that becomes increasingly difficult as the surface light source element becomes larger. The thickness of the support substrate is not particularly limited, but is usually 1 mm to 5 mm, and more preferably in the range of 2 mm to 4 mm, usually in view of weight reduction and strength. The support substrate may be improved in diffusibility by dispersing fine particles that diffuse light inside, embossing on the surface, or applying fine particles. In the case of dispersing fine particles inside or embossing on the surface, it is preferable for production that the base material is a thermoplastic resin, and a suitable material is equivalent to the light control member. Further, the support substrate may be bonded to the light control member, for example, can be bonded with a transparent adhesive or the like, thereby simplifying the assembly process of the surface light source element, and further, the shift of the light control member and wrinkles Occurrence can be prevented.

  The light control member of the present invention can be used for light sources other than a plurality of point light sources. For example, by using it for a single point light source, it is possible to obtain uniform and high luminance in a wider range. The plurality of convex portions included in the light control member of the present invention are a plurality of linear light sources arranged in a virtual plane parallel to the XY plane, parallel to the X-axis direction and along the Y-axis, or Y It is possible to control the direction of light rays from a plurality of linear light sources arranged in parallel to the axial direction and along the X-axis direction, and high luminance uniformity can be realized. As these linear light sources, it is also possible to use a linear light source configured by linearly arranging point light sources such as fluorescent lamps and LEDs at narrow intervals.

  The image display device of the present invention is realized by providing a transmissive display device on a surface light source element. Examples of the display device include a transmissive liquid crystal panel. As a result, it is possible to obtain an image display device that has excellent luminance uniformity and color uniformity on the display surface and excellent color reproducibility.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  The surface light source element shown in the schematic diagram of FIG. 1 was analyzed for luminance uniformity using illumination design analysis software LightTools (registered trademark). The conditions used for the analysis are described below.

  The point light source has one cylinder with a height of 0.5 mm and a diameter of 0.8 mm at the position of X = 0 and Y = 0, and uses the upper surface of the cylinder as a light-emitting part, and the angular characteristics of light emission are Lambertian. Distribution (Lambertian) was used. A reflecting plate that diffusely reflects was disposed on the lower surface side of the point light source, and a light control member was disposed at a position 25 mm from the reflecting plate. The light control member is assumed to be a general optical resin such as polystyrene resin, and the refractive index is set to 1.59.

  Using the above model, the luminance from the front direction with one point light source was analyzed by simulation, and the uniformity of the luminance when a plurality of point light sources were arranged was calculated from the result of one point light source. At this time, assuming that the luminance in the front direction at the X and Y positions as a result of the simulation with one point light source is L (X, Y), the luminance L ′ (X when a plurality of point light sources are arranged , Y) was obtained from the following equation.

With respect to the luminance distribution L ′ (X, Y) when a plurality of point light sources are arranged, the maximum luminance and the minimum luminance are _calculated from the maximum luminance L _xmax and the minimum luminance L _xmin in the interval between the point light sources along the X-axis direction. The ratio R _x = L _xmin / L _xmax was calculated as an index of luminance uniformity in the X-axis direction. Similarly, from the maximum luminance L _ymax and the minimum luminance L _ymin in the interval between the point light sources along the Y-axis direction, the ratio of the maximum luminance to the minimum luminance R _y = L _ymin / L _ymax is _determined as the luminance in the Y-axis direction. Calculated as an index of uniformity.

Table 1 shows the values of R _x and R _y obtained in Examples and Comparative Examples and the analysis conditions.

In the first embodiment, the convex portion of the light control member has a polynomial in cross-sectional outline in an arbitrary plane parallel to the XZ plane and a cross-sectional outline in an arbitrary plane parallel to the YZ plane. Where the coordinates of the X-axis, Y-axis, and Z-axis directions of the convex portion are x, y, and z, respectively.
z (x, y) = f ₁ (x) + g ₁ (y)
As a result, the obtained shape was simulated. A plurality of point light sources were arranged periodically along the X-axis direction and the Y-axis direction with D _x = 20 mm and D _y = 23 mm. In this case, a light source image is reduced in both the X-axis direction and the Y-axis direction, and a high-quality surface light source element with high luminance uniformity can be obtained.

In the second embodiment, the convex portion of the light control member has a cross-sectional outline in a plane of quality parallel to the XZ plane and a cross-sectional outline in an arbitrary plane parallel to the YZ plane as a parabola. And the coordinates of the X-axis, Y-axis, and Z-axis of the convex part are x, y, and z, respectively.
z (x, y) = f ₂ (x) + g ₂ (y)
As a result, the obtained shape was simulated. The plurality of point light sources were arranged periodically along the X-axis direction and the Y-axis direction with D _x = 20 mm and D _y = 33 mm. In this case, it is possible to widen the light source image especially in the Y-axis direction, and even when the interval between the light sources in the Y-axis direction is widened, high luminance uniformity can be obtained, and a high-quality surface light source An element is obtained.

  As Comparative Examples 1 and 2, analysis was performed when microlenses were arranged as convex portions in the light control member. In the comparative example 1, the microlenses have hemispheres having a radius of 0.15 mm arranged in a lattice pattern at intervals of 0.3 mm, and the height of the microlens is 0.15 mm. In Comparative Example 2, hemispheres having a radius of 0.2 mm are arranged in a lattice pattern at intervals of 0.3 mm, and the height is 0.13 mm. In this case, the light source images in the X-axis direction and the Y-axis direction cannot be reduced, the luminance uniformity is low, and the quality is lowered.

  As Comparative Example 3, an analysis was performed when a quadrangular pyramid was arranged as a convex portion in the light control member. The square pyramids had a width of 0.3 mm and a height of 0.15 mm, and were arranged in a grid at intervals of 0.3 mm. In this case, light incident on the light control member at an angle near the front direction at the position of the point light source does not transmit in the front direction, and the luminance in the front direction at the position of the point light source is very low. Therefore, the luminance uniformity is low and the quality is poor.

It is a figure which shows a suitable example of the surface light source element of this invention. It is a figure which shows the principle which deflects light to Z-axis direction vicinity with the surface light source element of this invention. As an example of the convex portion is a diagram showing a width a ₁ and a height b ₁ of the contour line in cross-section. It is a figure which shows an example of the arrangement | sequence for every unit of the some point light source in the surface light source element of this invention. It is a figure which shows an example of the arrangement | sequence for every unit of the some point light source in the surface light source element of this invention. It is a figure which shows an example for every arrangement | sequence unit of the some point light source in the surface light source element of this invention. It is a figure which shows an example of the arrangement | sequence of several point light sources in the surface light source element of this invention. It is a figure which shows an example of the arrangement | sequence of several point light sources in the surface light source element of this invention. It is a figure which shows an example of the arrangement | sequence of several point light source groups in the surface light source element of this invention.

Explanation of symbols

1: Point light source 1a: Red LED
1b: Blue LED
1c: Green LED
1d: LED of the fourth color
11: 1 unit of array of point light sources in which a plurality of point light sources are present 2: light control member 21: a plurality of convex portions in light control member 3: reflector 41: Z axis from point light source to light control member Incident light 42: Light that is refracted in the vicinity of the Z-axis direction by the convex portion from the light control member 43: Light that is reflected in the back direction by the convex portion of the light control member 51: On the XZ plane Parallel plane 52: XY plane 52: parallel to XY plane y: y2 plane 61: 51 plane, convex section cross-sectional contour 62: 52 plane 52: 52 Cross-sectional outline

a ₁ : Width of the contour line of the cross-sectional shape in the plane parallel to the XZ plane of the convex part b ₁ : Height of the contour line of the cross-sectional shape in the plane parallel to the XZ plane of the convex part a ₂ : The width b ₁ of the contour line of the cross-sectional shape in the plane parallel to the YZ plane of the convex portion: the height θ ₁ of the contour line of the cross-sectional shape in the plane parallel to the YZ plane of the convex portion , The maximum inclination angle θ ₂ of the contour line of the cross-sectional shape in the plane parallel to the XZ plane: the maximum inclination angle x of the contour line of the cross-sectional shape in the plane parallel to the YZ plane x: on the convex part , X-axis direction coordinate y: on the convex portion, Y-axis direction coordinate z: on the convex portion, Z-axis direction coordinate f (x): sectional shape of the convex portion in a plane parallel to the XY plane Function g (y) representing the contour line of the projection: Function D representing the contour line of the cross-sectional shape of the convex portion in a plane parallel to the YZ plane _x : Distance between point light sources along the X-axis direction D _y : Distance between point light sources along the Y-axis direction L: Analysis result of luminance in the front direction when there is one point light source L ′: Plurality Luminance L _{xmin in} the front direction when the point light sources are arranged: Minimum luminance L _{xmax in} the interval between the point light sources along the X-axis direction: Maximum luminance R _x in the interval between the point light sources along the X-axis direction: Ratio of L _xmin and L _xmin (= L _xmin / L _xmax )
L _ymin : Minimum luminance L _{ymax at} the interval between the point light sources along the Y-axis direction: Maximum luminance R _y at the interval between the point light sources along the Y-axis direction R _y : Ratio of L _ymin and L _ymin (= L _ymin / L _ymax )

Claims (7)

One of the normals of the XY plane parallel to the X axis and the Y axis orthogonal to the X axis is defined as the Z axis direction.
at least,
A light emitting surface parallel to the XY plane, a plurality of point light sources, and a sheet-like or film-like light control member,
The plurality of point light sources are arranged in a virtual plane parallel to the XY plane,
The light control member is arranged in parallel to the XY plane and on the Z-axis direction side of the plurality of point light sources,
The light-emitting surface is a surface light source element disposed on the Z-axis direction side of the light control member,
The light control member has a plurality of convex portions on the surface from which light is emitted mainly,
The plurality of convex portions,
The cross-sectional shape in an arbitrary plane parallel to the XZ plane is constant,
and,
A surface light source element having a constant cross-sectional shape in an arbitrary plane parallel to the YZ plane. The surface light source element according to claim 1,
The surface light source element, wherein the plurality of point light sources are periodically arranged in the X-axis direction and periodically arranged in the Y-axis direction. The surface light source element according to claim 1 or 2,
The contour line of the cross-sectional shape in a plane parallel to the XZ plane of the plurality of convex portions consists of a part of a curve made of an ellipse, a parabola, or a polynomial,
and,
A surface light source element, wherein a contour line of a cross-sectional shape in a plane parallel to the YZ plane is formed of a part of a curve made of an ellipse, a parabola, or a polynomial. The surface light source element according to claim 1,
The ratio b ₁ / a ₁ of the contour line width a ₁ and the contour line height b ₁ in a plane parallel to the XZ plane of the plurality of convex portions is 0.28 to 0.65. Yes,
and,
A surface having a ratio b ₂ / a _{2 of} a contour line width a ₂ and a contour line height b ₂ in a plane parallel to the YZ plane is 0.28 to 0.65. Light source element. The surface light source element according to any one of claims 1 to 4,
The maximum inclination angle θ1 of the contour line of the cross-sectional shape in a plane parallel to the XZ plane of the plurality of convex portions is 50 degrees to 82 degrees,
and,
A surface light source element, wherein the maximum inclination angle θ2 of the contour line of the cross-sectional shape in a plane parallel to the YZ plane is 50 degrees to 82 degrees.   The sheet-like or film-like light control member with which the surface light source element of any one of Claims 1-5 is provided.   An image display device comprising: a transmissive display device disposed on a light emitting surface of the surface light source element according to claim 1.