JP2010249851A - Light source element, light control member, and image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve screen quality by enhancing uniformity of brightness in a front direction and an oblique direction in a direct type illumination surface light source element enhancing front brightness and light use efficiency. <P>SOLUTION: The surface light source element replaces a fine particle diffusion plate used generally with a light control member 2 having a first ridge-like projection 241 and a second ridge-like projection 242 on an emission face. Light incident in the oblique direction with the second ridge-like projection 242 is deflected in the neighborhood of the front direction. In addition, light emitted in a largely oblique direction from the second ridge-like projection 242 is made incident on the first ridge-like projection 241, and uniformity of high brightness of the front direction and the oblique direction is achieved by being returned to a light source side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  For example, surface light source elements used in image display devices include 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 the diffusion plate, the light is made uniform by the diffusion plate, and the light is extracted to the exit surface opposite to the incident surface.

  In an image display device used for a mobile phone or a mobile personal computer, thinness of the device is required. Therefore, an edge light method that is advantageous for thinning is mainly used by providing a light source at a side end of the device. On the other hand, with respect to television and personal computer monitors, there are increasing demands for larger image display devices, higher brightness, and lower power consumption. In a large screen, the ratio of the length of the peripheral portion to the screen area is reduced, and sufficient luminance cannot be obtained. In addition, the light guide plate becomes thick and the weight increases. Therefore, the direct type is the mainstream for large surface light source elements.

  In the direct-type surface light source element, improvement in luminance uniformity, improvement in front luminance, reduction in thickness, and reduction in power consumption, that is, energy saving are required. The luminance uniformity is particularly important for eliminating the light / dark difference in the screen due to the light source image, and is important for applications such as image display devices and illuminated signboards.

The direct-type surface light source element includes a light source, a reflection plate, a diffusion plate, a diffusion sheet, and the like. The reflection plate reflects light emitted from the light source to the back side in the front direction, and the diffusion plate has a function of reducing the image of the light source in which fine particles that diffuse light are dispersed. Further, a diffusion sheet or a prism sheet is used in order to further improve the luminance uniformity and improve the front luminance.

  Means for realizing high luminance uniformity include arranging a large number of light sources densely and increasing the number of fine particles of the diffusion plate, both of which are not preferable from the viewpoint of energy saving.

  As another means for improving the luminance uniformity and the front luminance, it has been proposed to give the reflector a unique shape (see, for example, Patent Document 1), but it needs to be aligned with the light source and produced. Thinning may be hindered by a decrease in efficiency and the shape of the reflector. In addition, for each light source, a method of installing a reflecting member facing the light source (for example, see Patent Document 2) and a method of installing a light beam direction conversion element such as a Fresnel lens for each light source (for example, Patent Document 3). Have been proposed, but accurate alignment with the light source is required, leading to a reduction in production efficiency.

  In addition, in order to improve luminance uniformity, it has been proposed to use a diffuser plate in which a ridge-shaped convex portion is formed on the exit surface (see, for example, Patent Document 4 and Patent Document 5). This diffuser plate is suitable from the viewpoint of energy saving because it achieves a significant reduction or no use of fine particles for diffusing light and has high light use efficiency. In addition, high production efficiency can be obtained because there is no need for precise alignment with the light source. However, although this diffuser plate can obtain high luminance uniformity in the front direction, the light source image is viewed from the oblique direction, and when used in an image display device, the screen quality is degraded.

Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A JP 2006-343672 A JP 2007-12517 A

  Therefore, in the present invention, for example, a direct-type surface light source element used for an image display device or the like, which has high luminance, high luminance uniformity in the front direction and oblique direction, and utilization of light. An object of the present invention is to provide a surface light source element with high efficiency and productivity, a light control member included in the surface light source element, and an image display device using the surface light source element.

  In the present invention, a diffusion plate in which fine particles for diffusing light, which are generally used, are dispersed is used as a light control member having first and second ridge-like convex portions alternately arranged on the exit surface. The above-mentioned problem is solved by replacing. Specifically, the light control member can control the light emitted in the oblique direction by causing the light emitted in the unnecessary direction by the second hook-shaped convex portion to enter the first hook-shaped convex portion again. A first hook-like convex part and a second hook-like convex part.

That is, one aspect of the surface light source element of the present invention is:
One of the normals of the XY plane parallel to the X axis and the Y axis perpendicular to the X axis is defined as the front direction,
Comprising at least a plurality of light sources, a reflecting plate for reflecting light from the plurality of light sources, and at least one sheet-shaped or film-shaped light control member,
The reflector and the light control member are arranged in parallel to the XY plane,
The plurality of light sources are discretely arranged in a virtual plane parallel to the XY plane,
The surface light source element in which the reflector, the plurality of light sources, and the light control member are arranged in this order toward the front direction,
The light control member is
Mainly on the side from which light is emitted, a plurality of first hook-shaped protrusions orthogonal to the X-axis and parallel to the Y-axis, and a plurality of second hook-shaped protrusions orthogonal to the X-axis and parallel to the Y-axis Comprising light control means
The first hook-shaped protrusions and the second hook-shaped protrusions are alternately arranged along the X-axis direction,
The cross-sectional width of the first hook-shaped convex portion in a plane parallel to the X axis and perpendicular to the Y axis is a1,
B1 is the height of the first hook-shaped protrusion.
A cross-sectional width of the second hook-shaped convex portion in a plane parallel to the X axis and perpendicular to the Y axis is a2,
The height of the second hook-shaped convex part is b2,
θ = tan-1 [(a1 + a2) / 2 / (b1-b2)]
In this case, θ is 40 degrees or more and 60 degrees or less.

In one aspect of the surface light source element of the invention,
The maximum value of the inclination with respect to the X-axis of the outline of the cross section of the first hook-shaped convex portion parallel to the X-axis and perpendicular to the Y-axis is in the range of 52 degrees or more and 80 degrees or less.

Furthermore, in one aspect of the surface light source element of the invention,
It is preferable that the maximum value of the inclination with respect to the X axis of the contour line of the cross section of the second hook-shaped convex portion parallel to the X axis and perpendicular to the Y axis is in a range of 45 degrees to 80 degrees,
It is preferable that the outline of the cross section of the first hook-shaped convex portion parallel to the X axis and orthogonal to the Y axis is a curve formed of an ellipse, a parabola, or a part of a polynomial.
Furthermore, it is preferable that the contour line of the cross section of the second hook-shaped convex portion parallel to the X axis and orthogonal to the Y axis is composed of an ellipse, a parabola, or a part of a polynomial,
A ratio b1 / a1 between the cross-sectional width a1 of the first hook-shaped convex portion and the height b1 of the first hook-shaped convex portion in a plane parallel to the X axis and perpendicular to the Y axis is 0.28 or more and 0.00. It is preferable that it is 58 or less.

  Moreover, one aspect of the light control member of the present invention is a member provided in the surface light emitting element described above. Furthermore, in one aspect of the image display device of the present invention, a transmissive display device is arranged in the front direction of the surface light source element described above.

  The light control member used in the present invention includes light control means including a first hook-shaped convex portion and a second hook-shaped convex portion on the emission surface, and secondly outputs light emitted obliquely from the second hook-shaped convex portion. By making it incident on the ridge-shaped convex part, control of light emitted in the front direction and control of light in the diagonal direction are realized, and high luminance uniformity is achieved by reducing the light source image in both the front direction and the diagonal direction. It has a function.

  By using a light control member having a light control means, it is possible to avoid or greatly reduce the use of a fine particle diffusing material, and to reduce light absorption and light emission in unnecessary directions. Use efficiency can be improved and energy saving can be realized.

  In addition, since the light control member used in the present invention has uniform optical performance on the main surface, there is no need for strict alignment with the light source or the reflecting plate, and high productivity can be obtained.

It is a figure which shows an example of the surface light source element of embodiment of this invention. It is a figure which shows an example of the form which used the point light source as a light source. It is a figure which shows the direction of the light which injected into the light control member in this invention. It is a figure which shows the direction of the light which injected into the bowl-shaped convex part. It is a figure which shows the direction of the light which injected into the light control member which has only a 1st hook-shaped convex part. It is a figure which shows the direction of the light which injected into the light control member which has only a 2nd hook-shaped convex part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  The surface light emitting device according to the present invention includes at least a plurality of light sources, a reflecting plate, light, and a normal direction of an XY plane parallel to the X axis and a Y axis orthogonal to the X axis. And a control member. The light control member has a first hook-like convex part and a second hook-like convex part mainly on the side from which light is emitted. Hereinafter, it demonstrates concretely using drawing.

(Embodiment 1)
An example of the surface light source element of Embodiment 1 of this invention is shown in FIG. In the surface light emitting device shown in FIG. 1, an example is shown in which a linear light source 1, a light control member 2, and a reflection sheet 3 are provided as a plurality of light sources. In the light control member 2, the first hook-shaped protrusions 241 and the second hook-shaped protrusions 242 are alternately arranged mainly on the light emitting side. In the following description, the first hook-like convex part 241 and the second hook-like convex part 242 are also referred to as “light control means”. The light control member 2 includes an exit surface. In the following description, out of the surfaces parallel to the main surface of the light control member 2, the side that emits light, which is opposite to the light source side, is the emission surface.

  The reflection plate has a function of reflecting light emitted 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 (Polyethylene Terephthalate) 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 luminance uniformity, the material is preferably diffusely reflected. This includes foamed PET and the like.

  The light source is not particularly limited, but a linear light source such as a fluorescent tube or a point light source such as an LED (Light Emitting Diode) can be used. A linear light source in which point light sources such as LEDs are linearly arranged at narrow intervals can also be used.

  By using a point light source such as an LED, high color reproducibility can be realized, and a surface light source element with high screen quality can be obtained. When a point light source is used, as shown in FIG. 2, two light control members 2 are arranged so that the ridge-shaped convex portions are orthogonal to each other, and the light source image can be erased two-dimensionally. Further, the second hook-shaped protrusion is provided only on the light control member 2 that makes the luminance uniform along a direction in which it is difficult to make the luminance uniform depending on the light source interval and the distance to the light source. It is possible to efficiently control the light beam by alternately arranging the light source and the surface light source element with high luminance and high productivity.

  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.

  It is desirable that the distance between adjacent light sources is narrow because the luminance uniformity is good and high luminance can be obtained. However, if the interval is too narrow, the number of light sources increases, power consumption is large, and cost is undesirable. The distance between the light sources is preferably 10 mm or more and 100 mm or less. More desirably, it is 15 mm or more and 50 mm or less.

  A longer distance between the light source and the light control member 2 is desirable because of high luminance uniformity. However, if the length is too long, the thickness of the entire apparatus increases, which is not preferable. The distance between the light source and the light control member 2 is preferably 5 mm or less and 50 mm. More desirably, it is 7 mm or more and 30 mm or less.

  The light control member 2 includes light control means including a first hook-like convex part 241 and a second hook-like convex part 242 on the exit surface. By making the light emitted from the second hook-shaped convex part 242 obliquely enter the first hook-shaped convex part 241, the light emitted in the front direction and the light control in the oblique direction are realized. It has a function of realizing high luminance uniformity with reduced light source images in both directions and oblique directions.

  Specifically, the light from the light source travels in the front direction at the position where the light source is disposed on the light incident surface of the light control member 2, and the light from the light source at the intermediate position between the light source and the light source. Travels diagonally. Therefore, by providing the first hook-like convex part 241 and the second hook-like convex part 242 orthogonal to the X axis and parallel to the Y axis on the surface from which light is emitted mainly of the light control member 2, an oblique direction It is possible to direct the light emitted to the front direction. The light control means will be described in detail below with reference to the drawings.

  FIG. 3 shows the light control member 2 including the light control means 24 having the first hook-like convex portion 241 and the second hook-like convex portion 242. FIG. 3 shows the principle of deflecting light incident in the oblique direction by the first hook-like convex part 241 and the second hook-like convex part 242 in the front direction.

In FIG. 3 and FIGS. 4 to 6 to be described later, reference numerals 41 to 48 are used to indicate light.
41: Light obliquely incident on the light control member 42: Light emitted by being deflected in the front direction by the inclined surface of the hook-shaped convex portion 43: Light 44 totally reflected by the inclined surface of the hook-shaped convex portion and returning to the light source side : Light 45 incident on the ridge-shaped convex portion at an angle near the front direction 45: Light incident on the ridge-shaped convex portion at an angle near the front direction 46: Light emitted at an angle close to the front 46: Front surface on the ridge-shaped convex portion Of light incident at an angle near the direction, light 47 returns to the light source side by total reflection: Of light incident on the hook-shaped convex portion at an angle near the front direction, light 48 that is largely deflected obliquely and emitted: Light that exits largely obliquely from the second hook-shaped convex part, enters the first hook-shaped convex part, and returns to the light source direction

FIG. 4 shows a light control member 2b including the light control means 21 having an arbitrary hook-shaped convex portion 211. The arbitrary hook-shaped protrusion 211 is not limited to the shape of the first hook-shaped protrusion 241 or the second hook-shaped protrusion 242 described above, and may have an arbitrary shape.
FIG. 4 shows how light travels in the light control member 2b having the ridge-shaped convex portion 211 on the surface from which light is mainly emitted. The light (reference numeral 41) that is incident obliquely on the light incident surface of the light control member 2b is refracted on the incident surface, is incident on the inclined surface of the bowl-shaped convex portion 211, and is refracted, thereby causing the front direction. The light is deflected to the vicinity and emitted (reference numeral 42).

  Here, in order to deflect a large amount of light inclined in a more oblique direction near the front direction at a position further away from the light source, a more inclined slope is required.

  FIG. 5 shows a light control member 2c including the light control means 22 having the first hook-shaped convex portion 221. FIG. 6 shows a light control member 2d including the light control means 23 having the second hook-shaped convex portion 231. At the position of the light source, light (reference numeral 44) incident at an angle near the front direction by the light control member 2c is partially incident near the top of the first hook-shaped convex portion 221 as shown in FIG. The light is emitted while maintaining a nearby angle (reference numeral 45), and part of the light is incident on the skirt of the first hook-shaped protrusion 221 and directed toward the light source side by a plurality of total reflections (reference numeral 46). However, when the inclined surface is more inclined than the first hook-shaped protrusion 221 as compared with the first hook-shaped protrusion 221, as shown in FIG. 6, the light incident on the skirt of the second hook-shaped protrusion 231 ( After the total reflection of the reference numeral 44), it is refracted from the vicinity of the top of the second hook-shaped convex portion 231 without being totally reflected again, and is largely inclined from the front direction and emitted from the light control member 2d (reference numeral 47). Therefore, when the surface light source element is observed from an oblique direction, the luminance uniformity is low and the quality is lowered.

Therefore, in the present invention, the hook-shaped protrusions arranged on the light control member 2 are alternately arranged with the first hook-shaped protrusions 241 and the second hook-shaped protrusions 242, and the hook-shaped protrusions to be arranged are arranged. Set the shape as follows. That is, the width a1 and the height b1 of the cross section in the plane parallel to the X axis and perpendicular to the Y axis of the first hook-shaped convex part 241 and parallel to the X axis of the second hook-like convex part 242 and perpendicular to the Y axis Next, the width a2 and the height b2 of the cross section in the plane to be set are set using the angle θ calculated by the equation (1). θ is the minimum angle from the front direction of the light emitted from the second hook-shaped convex part 242 and incident on the first hook-shaped convex part 241.
θ = tan-1 [(a1 + a2) / 2 / (b1-b2)] (1)
By setting the angle θ calculated by Expression (1) to 40 degrees or more and 60 degrees or less, high luminance uniformity is realized in the front direction and the oblique direction.

  By determining the width and height of the first hook-like convex part 241 and the second hook-like convex part 242 as described above, the light (reference numeral 44) incident at an angle near the front direction at the light source position is second. When the light is projected from the light control member 2 by being totally reflected at the skirt of the hook-shaped convex portion 242, refracted from the vicinity of the top of the second hook-shaped convex portion 242, and greatly inclined from the front direction, the adjacent first hook-shaped It is possible to re-enter the convex portion 241 and direct light toward the light source direction. In FIG. 3, this light reflection is shown by a one-dot broken line. Therefore, even when a large number of inclined slopes are provided on the second hook-shaped convex portion in order to improve the luminance uniformity in the front direction, high luminance uniformity can be realized even in the oblique direction.

  Further, when a reflection plate is provided on the back side of the light source, high luminance in the front direction can be obtained by directing light emitted with a large inclination in the oblique direction toward the light source and reflecting the light with the reflection plate.

  Describing in detail with reference to FIG. 3, light (reference numeral 44) incident at an angle near the front direction from the light source side of the light control member 2 enters the second hook-shaped protrusion 242 and the second hook-shaped protrusion 242. Is once totally reflected by the skirt portion of the second and is emitted again in the θ direction from the vicinity of the top portion of the second hook-shaped convex portion 242. This light is incident on the adjacent first hook-shaped convex portion 241, is totally reflected by the first hook-shaped convex portion 241, and is emitted from the light control member 2 to the light source side.

  As in the reflection of light indicated by the one-dot broken line in FIG. 3, the angle θ of the light emitted from the second hook-shaped convex part 242 and incident on the first hook-shaped convex part 241 is 40 degrees or more and 60 degrees or less. In this case, high luminance uniformity in the front direction and luminance uniformity in the oblique direction can be realized. If it is larger than this, the light incident on the light control member 2 at an angle near the front direction at the light source position, the light incident on the skirt of the second hook-shaped convex portion 242 is emitted obliquely, and the luminance is uniform in the oblique direction. The performance is greatly reduced. On the other hand, if it is smaller than this, the proportion occupied by the second hook-like convex part 242 becomes small, the luminance uniformity in the front direction cannot be improved, and the first hook-like convex part 241 and the second hook-like convex part Since the width of 242 is greatly different, productivity is lowered. When the angle θ is not less than 42 degrees and not more than 55 degrees, luminance uniformity in the front direction and the oblique direction can be realized, and more preferably, not less than 45 degrees and not more than 50 degrees.

  As described above, the light control member 2 of the present embodiment includes the light control means 24 including the first hook-like convex portion and the second hook-like convex portion on the emission surface, and from the second hook-like convex portion 241. By making the light emitted in the oblique direction incident on the first hook-shaped convex portion 241, control of the light emitted in the front direction and control of the light in the oblique direction are realized, and the light source image is obtained in both the front direction and the oblique direction. It has a function to realize reduced high brightness uniformity.

  Further, in this embodiment, the use of the light control member 2 having the light control means 24 can avoid or greatly reduce the use of the fine particle diffusing material, and can absorb light or emit light in an unnecessary direction. Therefore, the light utilization efficiency can be improved and energy saving can be realized.

  In addition, since the light control member 2 used in the present invention has uniform optical performance on the main surface, there is no need for strict alignment with the light source and the reflecting plate, and high productivity can be obtained. For this reason, cost reduction can be realized.

(Embodiment 2)
In the present embodiment, the shapes of the first hook-shaped protrusion 241 and the second hook-shaped protrusion 242 will be described with reference to FIG. The configuration of the surface light source element is the same as that in FIG. 1 or FIG.

  If the maximum value of the inclination of the first saddle-shaped convex portion 241 in the light control member 2 with respect to the X-axis of the contour line of the cross section parallel to the X-axis and orthogonal to the Y-axis is excessively small, light from a position away from the light source When the light incident obliquely on the control member 2 cannot be directed to the front, and only the light incident at a small angle with respect to the front direction is emitted in the front direction. There is. On the other hand, if the maximum value of the inclination with respect to the X axis of the contour line of the cross section parallel to the X axis and perpendicular to the Y axis of the first hook-shaped convex portion 241 is excessively large, the light incident in the oblique direction is also directed in the front direction. Although it can be emitted, it becomes more difficult to mold and the productivity is lowered. Therefore, in the first bowl-shaped convex part 241, when the maximum value of the inclination of the contour line with respect to the X axis is 52 degrees or more and 80 degrees or less, the luminance uniformity is high, the moldability is good, and the productivity is high. It is possible to obtain a light source element. This angle is more preferably not less than 60 degrees and not more than 78 degrees, and more preferably not less than 62 degrees and not more than 76 degrees.

  By setting the maximum inclination of the contour of the cross section of the first hook-shaped convex portion 241 parallel to the X axis and perpendicular to the Y axis to the X axis in the range of 52 degrees to 80 degrees, the light source extends in the X axis direction. A large amount of light incident on the light control member 2 at a distant position can be directed to the front direction while maintaining high luminance uniformity in the oblique direction, reducing the light source image and reducing the light source image. High luminance uniformity can be realized. Furthermore, by making the maximum value of the inclination with respect to the X axis of the outline of the cross section of the first hook-shaped convex portion 241 parallel to the X axis and orthogonal to the Y axis, from 52 degrees to 80 degrees, the moldability becomes good. High productivity can be realized.

  In addition, if the maximum value of the inclination with respect to the X axis of the contour line of the cross section parallel to the X axis and perpendicular to the Y axis of the second hook-shaped convex portion 242 in the light control member 2 is excessively small, the position away from the light source Therefore, the light incident obliquely on the light control member 2 cannot be directed to the front, and the uniformity of luminance is reduced. On the other hand, if the maximum value of the inclination with respect to the X axis of the contour line of the cross section parallel to the X axis and perpendicular to the Y axis of the second bowl-shaped convex portion 242 is excessively large, the light incident in the oblique direction is also directed in the front direction. Although it can be emitted, it becomes more difficult to mold and the productivity is lowered. When the maximum value of the inclination of the contour line with respect to the X-axis is not less than 45 degrees and not more than 80 degrees, it is possible to obtain a surface light source element with high brightness uniformity, good moldability, and high productivity. This angle is more preferably not less than 50 degrees and not more than 78 degrees, and more preferably not less than 53 degrees and not more than 76 degrees.

  By setting the maximum inclination of the contour line of the cross section of the second hook-shaped convex part 242 parallel to the X axis and perpendicular to the Y axis to the X axis from 45 degrees to 80 degrees, it is separated from the light source in the X axis direction. More light incident on the light control member 2 at the position can be directed in the front direction, and high luminance uniformity can be realized. Furthermore, it is possible to direct more light incident on the light control member 2 at an angle near the front direction to the light source side, it is possible to equalize the energy distribution of the light, and uniform brightness in the front direction and the oblique direction. Can improve the performance. Furthermore, by making the maximum value of the inclination with respect to the X axis of the contour line of the cross section of the second hook-shaped convex part 242 parallel to the X axis and orthogonal to the Y axis, the moldability becomes good, High productivity can be realized.

In addition, the light control member 2 is configured such that the contour line of the cross section of the first hook-shaped convex portion 241 that is parallel to the X axis and orthogonal to the Y axis is a curve made of an ellipse, a parabola, or a part of a polynomial. The light from the light source can be spread smoothly and smoothly, and a smooth and uniform luminance distribution can be realized. Further, by forming the ridge with a smooth curved surface, high productivity and durability such as good moldability and resistance to breakage are realized.
Further, the light control member 2 is configured such that the contour line of the cross section of the second hook-shaped convex portion 242 that is parallel to the X axis and orthogonal to the Y axis is a curve composed of an ellipse, a parabola, or a part of a polynomial. The light from the light source can be spread smoothly and smoothly, and a smooth and uniform luminance distribution can be realized. Further, by forming the ridge with a smooth curved surface, high productivity and durability such as good moldability and resistance to breakage are realized.

  When the ratio b1 / a1 of the cross-sectional width a1 to the height b1 is smaller than 0.28 on the plane parallel to the X axis and perpendicular to the Y axis of the first hook-shaped convex portion 241 in the light control member 2, the light source Light incident at an angle inclined with respect to the front direction cannot be efficiently changed to the front direction, and it is difficult to improve the uniformity of luminance. When b1 / a1 is larger than 0.58, the light incident on the light control member 2 at an angle near the front direction is totally reflected on the skirt of the first hook-shaped protrusion 241 and the first hook-shaped protrusion By emitting light from the vicinity of the top of the portion 241 at a large angle in the oblique direction with respect to the front direction, the luminance uniformity in the oblique direction is greatly reduced. When the ratio b1 / a1 between the cross-sectional width and height of the first hook-shaped convex portion 241 is 0.28 or more and 0.58 or less, it is possible to efficiently direct light from the light source in the front direction. A surface light source element having high luminance uniformity between the direction and the oblique direction can be obtained. b1 / a1 is more preferably 0.30 or more and 0.56 or less, and further preferably 0.32 or more and 0.55 or less.

  As described above, the light control member 2 has a ratio b1 between the cross-sectional width a1 of the first hook-shaped protrusion 241 and the height b1 of the first hook-shaped protrusion 241 in a plane parallel to the X axis and orthogonal to the Y axis. By setting / a1 to be 0.28 or more and 0.58 or less, the light source image can be effectively reduced in the front direction and the oblique direction, and the uniformity of luminance can be improved. Moreover, since the ratio between the width and the height of the ridge is in a specific range, the moldability is good and high productivity is realized.

  When the ratio b2 / a2 between the cross-sectional width a2 and the height b2 on the plane parallel to the X axis and perpendicular to the Y axis of the second hook-shaped convex portion 242 in the light control member 2 is smaller than 0.38, the light source Therefore, it is difficult to efficiently deflect light incident at an angle inclined with respect to the front direction in the front direction, and it is difficult to obtain high luminance uniformity. On the other hand, when b2 / a2 is larger than 0.65, it is difficult to form the second hook-shaped convex portion, and the productivity is lowered. When the ratio b2 / a2 of the cross-sectional width to the height of the second hook-shaped convex part 242 is 0.38 or more and 0.65 or less, it is possible to efficiently direct the light from the light source in the front direction and the luminance. A surface light source element with high uniformity and high productivity can be obtained. b2 / a2 is more preferably 0.40 or more and 0.62 or less, and further preferably 0.42 or more and 0.59 or less.

  As described above, the light control member 2 has a ratio b2 between the cross-sectional width a2 of the second hook-shaped protrusion 242 and the height b2 of the first hook-shaped protrusion 241 in a plane parallel to the X axis and orthogonal to the Y axis. By setting / a2 to be not less than 0.38 and not more than 0.65, the light incident on the light control member 2 can be efficiently directed in the front direction at a position away from the light source in the X-axis direction. High uniformity in direction can be realized. In addition, it is possible to direct a large amount of light incident on the light control member 2 toward the light source at an angle near the front direction at the position of the light source, making the light energy uniform and realizing high brightness uniformity even in the oblique direction Is done. Furthermore, since the ratio of the width and height of the ridge is in a specific range, the moldability is good and high productivity is realized.

  Although it is desirable that the light control member 2 be thin, the surface light source element of the present invention, which is a direct type, has a space between the light source and the light control member 2, so that the strength without bending or deformation is high. It is desirable to have a thickness. Although the thickness of the light control member 2 varies depending on the size of the surface light source element, the thickness is preferably 0.5 mm or more and 5 mm or less. If it is thinner than this, the light control member 2 is bent or deformed, the light source and the light control member 2 come into contact with each other, and the appearance quality is deteriorated. If it is thicker than this, the surface light source element becomes thick and the weight also increases. More desirably, it is 1 mm or more and 4 mm or less, and more preferably 1.5 mm or more and 2.5 mm or less. In this range, the strength is maintained, and it is possible to suppress an increase in manufacturing cost due to an increase in the amount of base material used per main surface area.

  The cross-sectional width a1 in the plane parallel to the X axis and perpendicular to the Y axis of the first flange-shaped convex portion 241 in the light control member 2 is desirably 10 μm or more and 500 μm or less. 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, they are 20 micrometers or more and 400 micrometers or less, More desirably, they are 40 micrometers or more and 300 micrometers or less. In this range, the pattern itself is difficult to be visually recognized, and the production is facilitated and the productivity is improved. Furthermore, in the image display device in which the transmissive display device is provided on the emission surface side of the surface light source element of the present invention, a1 may be in the range of 1/100 to 1 / 1.5 of the pixel pitch of the transmissive display device. desirable. If it is larger than this, interference fringes with the pixel pitch are generated, and the appearance quality is lowered.

(Other embodiments)
The surface light source element according to the present invention includes a sheet-like or film-like light control member 2 provided with a first hook-like convex part 241 and a second hook-like convex part 242 that control the light beam direction along the X axis. Use. By using this light control member 2, the distribution of the light emitted from the light source in the front direction and the light emitted in the oblique direction is controlled, and high luminance and high luminance uniformity in the front direction and the oblique direction are realized. A surface light source element can be obtained. Here, a method for manufacturing the light control member 2 will be described.
Examples of the manufacturing method of the light control member 2 include extrusion molding, injection molding, and 2P (Photo Polymerization) molding using an ultraviolet curable resin. The size of the ridge-shaped protrusion, the shape of the ridge-shaped protrusion, and mass productivity A suitable molding method may be selected in consideration of the above.

  The first hook-like protrusions 241 and the second hook-like protrusions 242 in the light control member 2 are usually arranged alternately and continuously, but are flat between the first hook-like protrusions 242 and the second hook-like protrusions 241. A part may be provided. By providing the flat portion, the concave portion of the mold is hardly deformed, which is advantageous in forming the convex portion. In addition, since light directly above the light source is emitted in the front direction, it is effective in improving only the luminance directly above the light source. On the contrary, when the flat portion is not provided, the light beam direction can be controlled over the entire main surface of the light control member 2, so that the intensity distribution of the emitted light in the front direction can be easily made uniform.

  As a material of the light control member 2, 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.

  Further, in order to further improve the luminance uniformity, the light control member 2 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 or embossing on the main surface of the light control means, a method of providing fine particles for diffusing a small amount of light inside the structure, and emitting a diffusion sheet from the light control member 2 The method of providing in the surface side, or the method of combining 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. As for the degree of unevenness, the arithmetic average roughness Ra is desirably 3 μm or less. If it exceeds this range, the diffusion effect will be too great, and the front luminance will decrease.

  In the case where fine particles that diffuse light are provided inside the structure, the concentration of the fine particles can be kept very low compared to a normal diffusion plate. Any material used for a fine particle diffusion plate or the like as a material can be suitably 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.

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

  Further, a transparent support substrate made of resin, glass, or the like may be provided on the light source side of the light control member 2. By disposing the support substrate, it is possible to support the light control member 2 even if the light control member 2 is thinned to, for example, 0.1 mm to 1 mm. By making the light control member 2 thinner, molding by extrusion molding or the like is further facilitated, and productivity is improved. Further, as the surface light source element becomes larger, it becomes easier to support the light control member 2 that becomes increasingly difficult. Although there is no restriction | limiting in particular in the thickness of the said support substrate, Usually, it is 1 mm or more and 5 mm or less, and it is still more desirable that it is the range of 2 mm or more and 4 mm or less normally from the balance of weight reduction and intensity | 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 2. Further, the support substrate may be bonded to the light control member 2, 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 displacement of the light control member 2 And generation of wrinkles can be prevented.

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. Thereby, it is possible to obtain an image display device having a high display quality with high brightness on the display surface and high uniformity of brightness.
This is an image display device configured by disposing a transmissive display device in the front direction of the surface light source element. The surface light source element is a surface light source element with high uniformity of luminance in the front direction and the oblique direction. By arranging a transmission type display device on the exit surface side, the surface light source element is bright and high in luminance. Since the uniformity is high, it is possible to display a high-quality image. 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 is a device having at least an image display function using the display module, and includes a television, a personal computer monitor and the like.

Examples of the present invention will be described below, but the present invention is not limited thereto.
In order to obtain a plurality of light sources of the present invention, in this embodiment, fluorescent tubes with a diameter of 3 mm, which are linear light sources, are arranged at intervals of 30 mm. A reflector is arranged at a position 3 mm from the center of the fluorescent tube on the back side of the fluorescent tube, and a light control member 2 is arranged at a position 10 mm from the center of the fluorescent tube on the front side of the fluorescent tube. The structure of the surface light source element of an Example is shown in FIG.

  In this embodiment, in order to obtain the light control member 2 of the present invention, groove-shaped recesses in which the first hook-shaped protrusions and the second hook-shaped protrusions are reversed by cutting are continuously produced in parallel. A stamper is fabricated by electroforming nickel after producing a ridge-shaped convex portion from the mold thus obtained using an ultraviolet curable resin. By using the stamper, polystyrene (refractive index: 1.60) is injection-molded to produce a light control member 2 having a thickness of 2 mm and having a first hook-like protrusion and a second hook-like protrusion.

For the implemented configuration, the front luminance was measured using a luminance meter (BM-7 manufactured by Topcon Co., Ltd.) at a measurement angle range of 0.2 degrees, the measurement distance was constant, and the X-axis direction in which the light sources were arranged Measure for one cycle of the light source array while moving 1 mm each. L _1min is the minimum value of luminance in one cycle of the light source array in the front direction, and L _1max is the maximum value of luminance in one cycle of the light source array in the front direction.
In order to evaluate the luminance uniformity in the front direction, the ratio of L _1min that is the minimum value of luminance in one cycle of the light source array in the front direction and L _1max that is the maximum value is R ₁ = L _1min / L _1max Is calculated.

Further, the luminance in the oblique direction is measured for one period of the light source array while the luminance meter is tilted 65 degrees from the front direction and is moved by 1 mm in the X-axis direction in the same manner as the front luminance. L _2min is the minimum value of the luminance at the one period of the source array by tilting 65 degrees from the front direction, L _2max is luminance in one period of the source array by tilting 65 degrees from the front direction Is the maximum value.
To evaluate the uniformity of the oblique luminance, calculates the minimum value _{L 2min} luminance in one period of the oblique direction of the light source array, the ratio _R 2 _{= L} 2min _/ L _2max maximum value _{L 2max.}

  Next, in the surface light source element of this embodiment, a transmissive liquid crystal panel is arranged in the front direction of the exit surface, and the screen quality and screen brightness are observed.

  From this example, the first hook-like convex portion and the second hook-like convex portion achieve high brightness uniformity in the front direction, and the first hook-like convex portion emits from the second hook-like convex portion in an oblique direction. By directing light in the direction of the light source, high brightness uniformity is realized in both the front direction and the oblique direction. Next, when a transmissive liquid crystal panel is installed and observed in the front direction of the exit surface in the surface light source element of this embodiment, an image with good screen quality such as uniform brightness and high brightness is obtained.

  As Comparative Example 1, the linear light source was disposed in the same manner as in Example 1, and evaluation was performed when the light control member 2 in which the first hook-shaped convex portions were arranged in the X-axis direction was used. In this case, high brightness uniformity cannot be obtained in the front direction, and a light / dark difference due to the light source image is observed. Next, when a transmissive liquid crystal panel is arranged in the front direction of the exit surface in the surface light source element and observed, the image has low luminance uniformity and poor screen quality.

  As Comparative Example 2, the linear light source was arranged in the same manner as in Example 1, and evaluation was performed using the light control member 2 in which the second hook-shaped convex portions were arranged in the X-axis direction. In this case, high brightness uniformity cannot be obtained in the front direction, particularly in the oblique direction, and when viewed from the oblique direction, a light / dark difference due to the light source image is observed. Next, in this surface light source element, when a transmissive liquid crystal panel is arranged in the front direction of the exit surface and observed, an image with poor luminance uniformity and poor screen quality is observed when observed from an oblique direction.

Table 1 shows configurations and evaluation results of the examples and the comparative examples.
[Table 1 Configuration and Evaluation Results of Examples and Comparative Examples]

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. Moreover, each said embodiment can be combined, respectively.

DESCRIPTION OF SYMBOLS 1 Linear light source 2 Light control member 11 Point light source 21 Light control means 22 which consists of a bowl-shaped convex part Light control means 23 which consists only of a 1st bowl-shaped convex part Light control means 24 which consists only of a 2nd bowl-shaped convex part Light control means 3 composed of a first hook-shaped convex portion and a second hook-shaped convex portion Reflective sheet 41 Light 42 obliquely incident on the light control member Light 43 that is deflected in the front direction by the inclined surface of the hook-shaped convex portion and emitted Light that is totally reflected by the slope of the hook-shaped convex part and returns to the light source side 44 Light that enters the hook-like convex part at an angle near the front direction 45 Of the light that enters the hook-shaped convex part at an angle near the front direction Light 46 exiting at an angle close to the front 46 Of light incident on the ridge-shaped convex portion at an angle near the front direction, light returning to the light source side by total reflection 47 Light incident on the ridge-shaped convex portion at an angle near the front direction Of which light 48 is largely deflected in an oblique direction and emitted. From which the light exits largely obliquely, enters the first hook-shaped convex part, and returns to the light source direction.

a1 Cross-sectional width of the first hook-shaped protrusion in a plane parallel to the X axis and perpendicular to the Y axis b1 Height of the first hook-shaped protrusion a2 Parallel of the second hook-shaped protrusion to the X axis and to the Y axis Cross-sectional width b2 in the plane perpendicular to the height θ of the second hook-shaped convex portion The minimum angle from the front direction of the light emitted from the second hook-shaped convex portion and incident on the first hook-shaped convex portion

Claims (9)

One of the normals of the XY plane parallel to the X axis and the Y axis perpendicular to the X axis is defined as the front direction,
At least a plurality of light sources, a reflection plate that reflects light from the plurality of light sources, and at least one light control member formed of any one of a sheet shape and a film shape, and the reflection The plate and the light control member are arranged in parallel to the XY plane, and the plurality of light sources are discretely arranged in a virtual plane parallel to the XY plane, The plurality of light sources and the light control member are surface light source elements arranged in this order toward the front direction,
The light control member is
Light comprising a plurality of first hook-shaped protrusions orthogonal to the X-axis and parallel to the Y-axis and a plurality of second hook-shaped protrusions orthogonal to the X-axis and parallel to the Y-axis on the light emission side With control means,
The first hook-shaped protrusions and the second hook-shaped protrusions are alternately arranged along the X-axis direction,
For the first hook-shaped protrusion, the cross-sectional width in a plane parallel to the X-axis and perpendicular to the Y-axis is a1, the height of the first hook-shaped protrusion is b1, and the second hook-shaped protrusion is the X-axis A2 is a cross-sectional width in a plane parallel to the Y axis and perpendicular to the Y axis, and b2 is the height of the second hook-shaped protrusion
θ = tan-1 [(a1 + a2) / 2 / (b1-b2)]
The surface light source element is characterized in that θ is 40 degrees or more and 60 degrees or less.   2. The first saddle-shaped convex portion has a maximum inclination with respect to an X-axis of a contour line of a cross section parallel to the X-axis and perpendicular to the Y-axis, in a range of 52 degrees to 80 degrees. The surface light source element of description.   2. The second saddle-shaped convex portion has a maximum inclination of 45 degrees to 80 degrees with respect to an X axis of a contour line of a cross section parallel to the X axis and perpendicular to the Y axis. Or the surface light source element of 2. 4. The first saddle-shaped convex portion is formed of a curve in which a contour line of a cross section parallel to the X axis and perpendicular to the Y axis is an ellipse, a parabola, or a part of a polynomial. The surface light source element according to claim 1.   The said 2nd bowl-shaped convex part consists of a curve which the outline of the cross section parallel to a X-axis and orthogonal to a Y-axis consists of a part of an ellipse, a parabola, or a polynomial. The surface light source element according to claim 1.   A ratio b1 / a1 between the cross-sectional width a1 of the first hook-shaped convex portion and the height b1 of the first hook-shaped convex portion in a plane parallel to the X axis and perpendicular to the Y axis is 0.28 or more and 0.00. The surface light source element according to claim 1, wherein the surface light source element is 58 or less.   A ratio b2 / a2 between the cross-sectional width a2 of the second hook-shaped convex portion and the height b2 of the first hook-shaped convex portion in a plane parallel to the X axis and perpendicular to the Y axis is 0.38 or more and 0.00. The surface light source element according to claim 1, wherein the surface light source element is 65 or less.   The light control member with which the surface light source element as described in any one of Claims 1 thru | or 7 is provided.   An image display device comprising: a transmissive display device arranged in the front direction of the surface light source element according to claim 1.

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