JP2020021640A - Planar lighting system - Google Patents

Abstract

To compatibly achieve narrowing of a frame and widening of a color gamut by preventing colors from becoming uneven from nearby a light incidence face of a light guide plate.SOLUTION: A planar lighting system according to an embodiment comprises a light guide plate, a light source, an incidence prism, a longitudinal prism, and a light path change part. The light guide plate has a side face as an incidence face, and two principal surfaces. The light source includes a plurality of light emitting elements one of which is different in light emission color, and the plurality of light emitting elements are provided along the incidence surface. The incidence prism is provided on the incidence surface, and lets part of light from the light source travels in a first direction close to a direction substantially parallel with the incidence surface, and also lets light other than the light traveling in the first direction of the light from the light source travel in a second direction. The longitudinal prism extends in a direction substantially perpendicular to the incidence surface, and is so provided on one of the two principal surfaces as to have an uneven shape which is continuous in a cross section crossing the extending direction. The light path change part is provided on the other principal surface of the two principal surfaces, and changes the optical path of light in the light guide plate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a planar lighting device.

  2. Description of the Related Art Conventionally, there has been known a planar lighting device in which a plurality of light sources such as LEDs (Light Emitting Diodes) are arranged along a side surface of a light guide plate serving as a light incident surface while facing the side surface. Such a planar illumination device is used for, for example, a backlight of a liquid crystal display device, and in recent years, with a demand for a narrower frame for narrowing a frame portion of a light emission area, a wide area for improving color reproducibility. There is a strong demand for color gamut.

JP 2018-018813 A JP 2017-034148 A

  However, the above-described conventional technology has room for further improvement in achieving both narrower frame and wider color gamut while suppressing the occurrence of color unevenness near the light incident surface of the light guide plate.

  Specifically, for the purpose of widening the color gamut, the light source disposed on the side surface of the light guide plate includes two or more types of LED chips having different emission colors such as blue and green, for example, and it is desirable to mix colors externally. The light emitting device that obtains the color of (1) can be used as one unit light source. However, in such a case, there is a problem that color unevenness having a long distance from the vicinity of the light incident surface of the light guide plate is likely to occur, which hinders narrowing of the frame.

  The present invention has been made in view of the above, and is a planar illumination that can achieve both a narrower frame and a wider color gamut by suppressing the occurrence of color unevenness near the light incident surface of a light guide plate. It is intended to provide a device.

  In order to solve the above-described problem and achieve the object, a planar lighting device according to one embodiment of the present invention includes a light guide plate, a light source, a light distribution unit, a light diffusion unit, and an optical path changing unit. Prepare. The light guide plate has a side surface serving as a light incident surface and two main surfaces. The light source includes a plurality of light emitting elements each having a different emission color, and a plurality of the light sources are provided along the light incident surface. The light distribution unit is provided on the light incident surface, and a part of light from the light source travels in a first direction that is a direction close to a direction substantially parallel to the light incident surface, and light from the light source is emitted from the light source. The light other than the light traveling in the first direction is caused to travel in a second direction that is a direction substantially perpendicular to the light incident surface. The light diffusing portion extends in a direction substantially perpendicular to the light incident surface, and is provided on one of the two main surfaces so as to have a continuous uneven shape in a cross section intersecting the extending direction. Provided. The optical path changing unit is provided on the other main surface of the two main surfaces, and changes an optical path of light inside the light guide plate.

  According to one embodiment of the present invention, it is possible to achieve both narrow frame and wide color gamut while suppressing the occurrence of color unevenness near the light incident surface of the light guide plate.

FIG. 1A is a schematic plan view of the planar lighting device according to the embodiment. FIG. 1B is an image diagram of color unevenness. FIG. 1C is an exploded perspective view illustrating a configuration example of a planar lighting device according to a comparative example. FIG. 1D is a schematic sectional view illustrating a configuration example of the optical path changing member. FIG. 1E is a schematic plan view illustrating a traveling direction of light near a light incident surface in the surface illumination device according to the comparative example. FIG. 2 is an exploded perspective view illustrating a configuration example of the spread illuminating apparatus according to the embodiment. FIG. 3 is a schematic cross-sectional view illustrating a configuration example of the vertical prism according to the embodiment. FIG. 4 is a schematic plan view illustrating a configuration example of the light incident prism according to the embodiment. FIG. 5 is a schematic plan view illustrating a traveling direction of light near a light incident surface in the planar lighting device according to the embodiment. FIG. 6 is a diagram illustrating light distribution characteristics to a light guide plate. FIG. 7 is a schematic plan view illustrating a modification of the light entering prism according to the embodiment.

  Hereinafter, a planar lighting device according to an embodiment will be described with reference to the drawings. Note that the relationship between dimensions of each element in the drawings, the ratio of each element, and the like may be different from reality. Even in the drawings, there may be cases where portions having different dimensional relationships and ratios are included.

  In addition, in order to make the description easy to understand, a three-dimensional orthogonal coordinate system may be illustrated in each drawing. In such an orthogonal coordinate system, a main surface direction of a light guide plate described later is defined as an XY plane direction, and a thickness direction of the light guide plate is defined as a Z-axis direction. The “principal surface” refers to a principal surface on the front and back of the light guide plate, excluding a side surface that is a surface along the thickness direction of the light guide plate, and the principal surface direction refers to a plane direction of the principal surface.

  First, the outline of the configuration of the spread illuminating apparatus 1 according to the embodiment will be described with reference to FIG. 1A. FIG. 1A is a schematic plan view of the planar lighting device 1 according to the embodiment.

  As shown in FIG. 1A, the spread illuminating device 1 includes an emission area 2, light blocking members 3 and 4, and a plurality of light sources 5. The light-emitting area 2 is a planar area from which a plurality of light sources 5 emit light, and light from which the light is guided and diffused is defined by the light-blocking members 3 and 4. Inside the emission area 2, a light guide plate 21, a reflection sheet 22, a diffusion sheet 23 (see FIG. 1C and thereafter), which will be described later, and the like are stacked.

  The light-shielding members 3 and 4 are, for example, sheet-like members, and define the emission region 2 by covering both end portions in the longitudinal direction of the planar illumination device 1. The light shielding member 3 has a larger width than the light shielding member 4 to cover a region including the light source 5 and a flexible printed circuit (FPC) (not shown) on which the light source 5 is mounted. The width dimension of the light shielding member 3 is, for example, 2.5 mm or less.

  The plurality of light sources 5 each include a plurality of light emitting elements having different emission colors, and are provided along the side surface of the light guide plate 21 serving as a light incident surface. One of the light sources 5 is, for example, an LED package including a blue LED chip, a green LED chip, and a red phosphor, and by mixing light of these different colors externally, for example, white. Light of a desired color is emitted. As described above, by using the light source 5 including two or more types of LED chips having different emission colors, a wider color gamut can be achieved.

  The emission color and number of each LED chip constituting one light source 5, the color of the phosphor, and the like can be appropriately selected according to the amount of light and chromaticity to be obtained, and are limited to the examples described above. It is not something to be done. Although FIG. 1A illustrates five light sources 5, the number of light sources 5 in the planar lighting device 1 is not limited.

  Such a planar illumination device 1 is used, for example, as a backlight of a liquid crystal display device. The liquid crystal display device is used for a smartphone, for example.

  By the way, when the light source 5 including two or more types of LED chips having different emission colors is used as described above, it is known that color unevenness relatively long from the vicinity of the light incident surface of the light guide plate 21 may occur. ing. FIG. 1B is an image diagram of color unevenness. Although FIG. 1B is an enlarged schematic diagram of the portion M1 shown in FIG. 1A, for the sake of simplicity, one light source is shown as an example including three types (RGB) of LED chips.

  As shown in FIG. 1B, the color unevenness is caused by the fact that the colors of the LED chips of the light source 5 do not mix well in the vicinity of the light source 5 being mounted, that is, in the vicinity of the light incident surface of the light guide plate 21. Arising from In addition, such color unevenness has a relatively long generation distance.

  The reason will be described with reference to FIGS. 1C to 1E. First, a configuration example of a planar lighting device 1 ′ according to a comparative example will be described with reference to FIGS. 1C and 1D. FIG. 1C is an exploded perspective view illustrating a configuration example of a spread illuminating apparatus 1 ′ according to a comparative example. FIG. 1D is a schematic sectional view illustrating a configuration example of the optical path changing unit 6.

  As shown in FIG. 1C, the planar lighting device 1 ′ includes a light guide plate 21, a reflection sheet 22, a diffusion sheet 23, and a pair of prism sheets 24 and 25. The light guide plate 21 is a transparent member formed in a substantially rectangular thin plate shape, and is made of, for example, a polycarbonate resin.

  The plurality of light sources 5 described above are arranged along the light incident surface 21a, which is one side surface of the light guide plate 21, and the light emitted from the light source 5 and incident on the light incident surface 21a, and the guided light is The light is emitted from the emission surface 21b which is one of the main surfaces of the light guide plate 21.

  The reflection sheet 22 is disposed on the other of the main surfaces of the light guide plate 21, that is, on the reflection surface 21c opposite to the emission surface 21b. The reflection sheet 22 reflects the light to be emitted from the reflection surface 21c side and makes the light enter the light guide plate 21 again.

  In addition, on the reflection surface 21c side of the light guide plate 21, an optical path changing unit 6 which is a member for changing an optical path of light is provided. As shown in FIG. 1D, the optical path changing unit 6 is provided as a dot pattern arranged on the reflection surface 21c, for example, so as to be substantially uniformly distributed.

  Then, the light path changing unit 6 changes a part of the light path of the light reflected by the reflection surface 21c and advanced in the light incident on the inside of the light guide plate 21 from the light source 5 via the light entrance surface 21a. Then, the light is emitted from the emission surface 21b (see the portion M2 in the figure).

  In FIG. 1D, for convenience of explanation, the size and distribution of the optical path changing unit 6 are shown uniformly, but the light whose optical path has been changed by the optical path changing unit 6 is substantially uniform from the entire area of the emission surface 21b. The light path changing unit 6 can be provided so that the shape, size, distribution, and the like of the dot pattern are not uniform according to the distance from the light incident surface 21a so that the light is emitted.

  The optical path changing unit 6 is not a dot pattern, but a stepped prism or the like that is continuously formed in a direction substantially perpendicular to the light incident surface 21a (X-axis direction in the drawing) with respect to the reflection surface 21c. You can also

  Returning to the description of FIG. 1C. The diffusion sheet 23 is a member that diffuses light emitted from the emission surface 21b of the light guide plate 21 to make the brightness uniform. The pair of prism sheets 24 and 25 are members for adjusting the directional characteristics of the light diffused by the diffusion sheet 23 in two orthogonal directions. For example, both of the ridge lines of the prism point to the positive direction side of the Z axis in the drawing. The prisms are arranged so that the directions and the directions of the ridge lines of the prisms are orthogonal to each other.

  And in such a planar illumination device 1 ', the light from the light source 5 shows the traveling direction as shown in FIG. 1E near the light incident surface 21a. FIG. 1E is a schematic plan view illustrating a traveling direction of light near the light incident surface 21a in the planar illumination device 1 'according to the comparative example.

  In addition, in FIG. 1E, for easy understanding of the drawing, the traveling direction of only the A-color or B-color light emitted from one LED chip per one light source 5 is schematically illustrated.

  As shown in FIG. 1E, in the planar lighting device 1 ′ according to the comparative example, light emitted from the light source 5 enters the light entrance surface 21 a while having a certain divergence angle, and is guided by the light guide plate 21. The light is emitted, the light path is changed by the light path changing unit 6, and the light is emitted from the emission surface 21b.

  However, in the “first region” near the light entrance surface 21 a of the light guide plate 21, which is a region where the light emitted from the light source 5 gradually spreads from the light source 5 as a starting point, the so-called intersection of the light of each color from each light source 5. Are sparse and are not sufficiently mixed.

  Therefore, in the spread illuminating device 1 ′, if light of each color does not travel to the “second region” on the back side (positive direction side of the X-axis in the drawing) from the “first region”, sufficient color mixing will occur. Can not be obtained. For this reason, in the spread illuminating device 1 ′ according to the comparative example, color unevenness having a relatively long distance is generated from near the light incident surface 21 a of the light guide plate 21.

  In this regard, it is conceivable to make the color unevenness less visible by increasing the width of the light shielding member 3 described above. However, such measures cannot meet the demand for narrower frames, which has been increasing in recent years.

  Therefore, the planar lighting device 1 according to the embodiment includes a light distribution unit and a light diffusion unit. The light distribution unit is, for example, a light incident prism 8 described later, which is provided on the light incident surface 21a and allows a part of light from the light source 5 to travel in a direction close to a direction substantially parallel to the light incident surface 21a. The remaining part of the light from the light source 5 travels in a direction substantially perpendicular to the light incident surface 21a. The light diffusion portion is, for example, a vertical prism 7 described later, and extends in a direction substantially perpendicular to the light incident surface 21a, and is formed on the emission surface 21b so as to have a continuous uneven shape in a cross section intersecting the extending direction. Provided.

  Hereinafter, a configuration example of the planar lighting device 1 according to the embodiment will be described more specifically with reference to FIGS. 2 to 4. FIG. 2 is an exploded perspective view illustrating a configuration example of the planar lighting device 1 according to the embodiment. Note that FIG. 2 corresponds to FIG. 1C, and thus, in the description using FIG. 2, mainly different points from FIG. 1C will be described.

  FIG. 3 is a schematic sectional view illustrating a configuration example of the vertical prism 7 according to the embodiment. FIG. 4 is a schematic plan view illustrating a configuration example of the light incident prism 8 according to the embodiment.

  As shown in FIG. 2, the surface illumination device 1 according to the embodiment is different from the surface illumination device 1 ′ according to the comparative example in further including a vertical prism 7 and a light incident prism 8. The vertical prism 7 is, for example, a lenticular lens.

  The vertical prism 7 is an example of a light diffusing unit, and is provided on the emission surface 21b so as to extend in a direction substantially perpendicular to the light incident surface 21a (X-axis direction in the figure), as shown in FIG. .

  Further, as shown in FIG. 3, the vertical prism 7 is provided on the emission surface 21b so as to have a continuous uneven shape in a cross section intersecting with the extending direction (for example, a cross section along the YZ plane in the drawing).

  For example, in FIG. 2 and FIG. 3, the convex ridge 71 having an arc-shaped cross section serves as a convex portion, and is arranged in a direction (Y-axis direction in the drawings) substantially parallel to the light incident surface 21a at a predetermined interval with respect to the light exit surface 21b. An example of a vertical prism 7 which is formed continuously (repeatedly) and provided so as to have an uneven shape with the emission surface 21b as a concave portion is shown.

  When the vertical prism 7 is configured as described above, light incident on the light guide plate 21 can be reflected by the prism surface (curved surface), and a direction substantially parallel to the light incident surface 21a of the light guide plate 21 (Y axis in the drawing) Direction) irregularly. Thereby, the light traveling inside the light guide plate 21 can be made uniform.

  Note that the vertical prism 7 totally reflects the light incident in a direction substantially parallel to the extending direction of the convex body 71 (the X-axis direction in the drawing) inside the light guide plate 21 and externally reflects the light from the emission surface 21b. No light is emitted.

  On the other hand, the vertical prism 7 can emit light incident at an angle substantially perpendicular to the extending direction of the ridge 71 (an angle smaller than the critical angle) to the outside from the uneven surface. In the examples shown in FIGS. 2 and 3, the convex ridge 71 has an arc-shaped cross section. However, the cross-sectional shape of the convex ridge 71 is not limited. It may be.

  The light incident prism 8 is an example of a light distribution unit, and is provided on the light incident surface 21a along the extending direction of the light incident surface 21a (Y-axis direction in the figure), as shown in FIG. Specifically, as shown in FIG. 4, the light incident prism 8 is formed by a combination of a light incident surface 21a and a substantially trapezoidal unit prism 81 formed to project from the light incident surface 21a at a predetermined interval. Become.

  The unit prism 81 has an end surface 81a having a large inclination angle with respect to the light incident surface 21a, that is, an end surface 81a substantially perpendicular to the light incident surface 21a, and an end surface 81b substantially parallel to the light incident surface 21a. The end face 81a refracts light entering from the light source 5 and proceeds in a direction close to the normal line. That is, a part of the light from the light source 5 is made to travel in a direction close to a direction substantially parallel to the light incident surface 21a.

  On the other hand, the end surface 81b and the light incident surface 21a allow the remaining light from the light source 5 to travel in a direction substantially perpendicular to the light incident surface 21a.

  Although not shown in FIGS. 2 to 4, the spread illuminating apparatus 1 according to the embodiment has a configuration in which the above-described dot pattern as the optical path changing unit 6 is a reflection surface of the “first region” shown in FIG. 1E. This is different from the spread illuminating apparatus 1 ′ according to the comparative example in that it is not provided on the 21c side, or is provided so as to have a more sparse distribution than the “second region”.

  Next, the principle of solving the color unevenness by the planar illumination device 1 according to the embodiment configured as described above will be described with reference to FIG. FIG. 5 is a schematic plan view illustrating a traveling direction of light near the light incident surface 21a in the planar illumination device 1 according to the embodiment.

  As shown in FIG. 5, the planar lighting device 1 mixes light of different colors with a “first region”, that is, a band-like region substantially parallel to the light incident surface 21 a of the light guide plate 21 near the light incident surface 21 a. Then, the light is emitted. Hereinafter, the light emitted from the “first region” is referred to as “first mode light”.

  The spread illuminating device 1 is a “second region” already shown in FIG. 1E, that is, a region farther from the light incident surface 21a than the “first region”, and is adjacent to the “first region”. The region is a region that passes through the “first region” substantially perpendicularly to the light incident surface 21a, sufficiently mixes light with insufficient color mixture, and emits the light. The light emitted from the “second region” is hereinafter referred to as “second mode light”.

  First, the “first mode light” will be specifically described. As shown in FIG. 5, the light entering the light guide plate 21 from the end surface 81a of the light entrance prism 8 having a large inclination angle enters the light entrance surface 21a having a large divergence angle with respect to the light entrance surface 21a. It proceeds in a substantially parallel direction (see FIG. 4).

  Thereby, as shown in FIG. 1E, in the “first region” where the intersection of light of different colors is sparse, as shown in FIG. 5, such intersection is made dense, and light of different colors is sufficiently emitted. Can mix colors.

  Further, the light mixed in the “first region” is incident on the above-described vertical prism 7 at an angle almost perpendicular to the vertical prism 7, and therefore, at least a part of the mixed light is regarded as “first mode light”. The light is emitted from the surface of the ridge 71.

  By such an operation, it is possible to emit “first mode light” in which color unevenness is suppressed from the “first region”. In FIG. 5, the ridge 71 of the vertical prism 7 is illustrated as extending to the light incident surface 21 a of the light guide plate 21, but the ridge 71 is in the middle of the “first region”. The length may be up to. In other words, the vertical prism 7 does not need to be close to the light incident surface 21a, and may be provided so that the end face of the convex strip 71 is located away from the light incident surface 21a.

  Further, the length of each of the ridges 71 may not be constant. Further, the degree of protrusion of the ridge 71 (specifically, the tangent angle to the emission surface, the maximum tangent angle) is several degrees (2 °) to 10 ° in the “first region”, and is 10 ° in the “second region”. It may change in two regions, such as 10 ° to 30 °. Further, the “first region” and the “second region” are not always clearly separated, and there may be a region where the two regions are mixed.

  Next, the “second mode light” will be specifically described. Light entering the light guide plate 21 from the end face 81b of the light entrance prism 8 substantially parallel to the light entrance surface 21a (or with a small inclination angle) has a certain spread angle as shown in FIG. The light travels in a direction substantially perpendicular to the light incident surface 21a.

  Thus, different colors of light can be mixed in the “second region” that is separated from the light incident surface 21a by a predetermined distance. Light traveling in a direction substantially perpendicular to the light incident surface 21a and passing through the “first region” (that is, light with insufficient color mixture) is almost parallel to the vertical prism 7. Since the light is incident at an angle, the light is totally reflected inside the light guide plate 21 and is not basically emitted from the light guide plate 21 to the outside. That is, the “second mode light” is not emitted from the light guide plate 21 in a state where the color mixture is insufficient.

  On the other hand, the light that has been sufficiently mixed while being forwarded inside the light guide plate 21 with or without total reflection reflects the light path provided on the reflection surface 21c side of the “second region”. The optical path is changed by the changing unit 6, and the light is emitted from the emission surface 21b as "second mode light".

  By such an operation, it is possible to emit “second mode light” with suppressed color unevenness from the “second region”.

  Although FIG. 5 illustrates a case where the optical path changing unit 6 is not provided on the reflection surface 21c side of the “first region”, the distribution is provided so as to be more sparse than the “second region”. You may. Further, the optical path changing unit 6 may be provided so as to gradually decrease from the “second region” to the “first region”, that is, to decrease the number gradually. The “first region” is intended to prevent a member such as the reflection sheet 22 from sticking to the light guide plate 21 and has a level that does not substantially affect the emission of light from the emission surface 21b. Low density dots may be formed.

  In addition, the spread illuminating apparatus 1 according to the embodiment causes the light to enter the light guide plate 21 with the light distribution characteristics shown in FIG. FIG. 6 is a diagram showing light distribution characteristics to the light guide plate 21. The light distribution characteristic referred to here is an angle distribution of a light beam when an optical axis direction perpendicular to the light incident surface 21a is set to 0 °.

As shown in FIG. 6, the spread illuminating device 1 causes approximately 90% of the light to travel in a substantially vertical direction within ± 40 °. Therefore, most of the light travels through the “first region” to the “second region”, and in a state where the color is not sufficiently mixed, the light is not emitted from the vertical prism 7 to the outside, but is mixed inside the light guide plate 21. You. Thereafter, the optical path is changed by the optical path changing unit 6 and emitted as “second mode light”.

  On the other hand, the planar lighting device 1 causes the remaining light to travel in a substantially parallel direction of −90 ° to −50 ° or + 50 ° to + 90 °. Therefore, these lights intersect densely in the “first region” and are mixed with each other, and enter the vertical prism 7 at an angle almost perpendicular to the vertical prism 7 to be emitted as “first mode light” from the surface of the vertical prism 7. Will be done.

  In order to exhibit such light distribution characteristics, the configuration of the light incident prism 8 is not limited to that shown in FIG. A modification of the light incident prism 8 will be described with reference to FIG. FIG. 7 is a schematic plan view illustrating a modification of the light incident prism 8 according to the embodiment.

  As shown in FIG. 7, in the light incident prism 8, the unit prism 82 has an end surface 82a having a large inclination angle and an end surface 82b having a small inclination angle with respect to the light entrance surface 21a, and a virtual surface C parallel to the XZ plane. May be formed in a mirror-symmetrical shape with respect to a plane of symmetry.

  In such a case, the light incident prism 8 causes a part of the light from the light source 5 to enter the light incident surface 21a by an end surface 82a having a large inclination angle with respect to the light incident surface 21a, that is, substantially perpendicular to the light incident surface 21a. Proceed in a direction close to the substantially parallel direction.

  On the other hand, the light incident prism 8 has a small angle of inclination with respect to the light incident surface 21a, that is, an end surface 82b substantially parallel to the light incident surface 21a and the light incident surface 21a, and the remaining light from the light source 5 is formed. Is advanced in a direction substantially perpendicular to the light incident surface 21a while adjusting the spread angle to a predetermined value.

  That is, according to such a modification, it is also possible to configure the spread illuminating apparatus 1 so as to exhibit light distribution characteristics in two directions that are complementary to each other, according to the required specifications for the illumination characteristics.

  As described above, the planar lighting device 1 according to the embodiment includes the light guide plate 21, the light source 5 including a plurality of light emitting elements having different emission colors, and the light incident prism 8 (an example of the “light distribution unit”). , A vertical prism 7 (corresponding to an example of a “light diffusing unit”), and an optical path changing unit 6.

  The light guide plate 21 has a side surface serving as the light incident surface 21a and two main surfaces. One light source 5 includes a plurality of light emitting elements having different emission colors, and a plurality of light sources 5 are provided along the light incident surface 21a.

  The light incident prism 8 is provided on the light incident surface 21a, and allows a part of the light from the light source 5 to travel in a first direction which is a direction close to a direction substantially parallel to the light incident surface 21a. Out of the light traveling in the first direction travels in the second direction, which is a direction substantially perpendicular to the light incident surface 21a. The vertical prism 7 extends in a direction substantially perpendicular to the light incident surface 21a, and is provided on one of the two main surfaces so as to have a continuous uneven shape in a cross section intersecting the extending direction. . The light path changing unit 6 is provided on the other of the two main surfaces, and changes the light path of the light inside the light guide plate 21.

  Therefore, according to the planar illumination device 1 according to the embodiment, the light incident from the light incident surface 21a is substantially transmitted by the light incident prism 8 into the first direction substantially parallel to the light incident surface 21a and the light incident surface 21a. It can be advanced in a vertical second direction. Then, due to the interaction between the light traveling in the first direction and the vertical prism 7 and the light traveling in the second direction and the optical path changing section 6, two mode lights having different color mixing mechanisms and different emission areas are generated. be able to. Thereby, it is possible to realize a wide color gamut while suppressing the occurrence of color unevenness near the light incident surface 21a of the light guide plate 21 (that is, while maintaining a narrow frame).

  The light-entering prism 8 advances light in a first direction in a first area, which is a region near the light-entering surface 21a of the light guide plate 21 and is a band-like region substantially parallel to the light-entering surface 21a, Light travels in the second direction in the first region and in a second region, which is a region farther from the light incident surface 21a than the first region and is adjacent to the first region.

  Therefore, according to the spread illuminating device 1 according to the embodiment, the light incident prism 8 is applied as the light distribution unit, and the deflection function of the light incident prism 8 causes the first region near the light incident surface 21a to move in the first direction. It is possible to easily and arbitrarily generate light that travels and light that travels in the second direction in the second region farther from the light incident surface 21a than the first region.

  The vertical prism 7 is provided from the first area to the second area, and the optical path changing unit 6 is provided in the second area. Alternatively, the vertical prism 7 is provided from the first region to the second region, and the optical path changing unit 6 is provided from the first region to the second region, and the optical path is changed by the optical path changing unit 6 provided in the first region. Substantially all of the light is forwarded to the second area.

  Therefore, according to the spread illuminating apparatus 1 according to the embodiment, the first mode light is efficiently emitted from the first area without being affected by the optical path changing unit 6, and the optical path changing unit is output from the second area. 6, the second mode light can be emitted efficiently. That is, the emission areas of the first mode light and the second mode light can be made different. When the optical path changing section 6 is provided in the first area, the light path changed by the optical path changing section 6 in the first area so as not to substantially affect the emission of light from the emission surface 21b. Can be used to prevent the member such as the reflection sheet 22 from sticking to the light guide plate 21 by setting the optical path changing portion 6 in the first region to be advanced to the second region. .

  The vertical prism 7 is provided on an emission surface 21b which is a main surface for emitting light out of the two main surfaces, and the optical path changing unit 6 is provided on a reflection surface 21c which is a main surface on the opposite side to the emission surface 21b. Can be The optical path changing unit 6 is, for example, a dome-shaped dot pattern, and is provided so that the distribution is more sparse in the first area than in the second area. Therefore, according to the surface illumination device 1 according to the embodiment, the transition region can be provided between the first region and the second region, and the boundary between the first mode light and the second mode light is made inconspicuous. Can be. Further, the influence of the optical path changing unit 6 can be reduced more in the first region than in the second region.

  Further, the light incident prism 8 has end surfaces 81a and 82a (corresponding to an example of a “first end surface”) whose inclination angle is substantially perpendicular to the light entrance surface 21a, and an inclination angle substantially parallel to the light entrance surface 21a. End faces 81b and 82b (corresponding to an example of “second end face”). The end faces 81a and 82a refract light from the light source 5 in the first direction, and the end faces 81b and 82b allow light from the light source 5 to travel in the second direction.

  Therefore, according to the spread illuminating apparatus 1 according to the embodiment, by appropriately setting the inclination angles of the pair of inclined surfaces having different inclination angles in the light incident prism 8, the required specifications for suppressing the chromaticity unevenness are satisfied. Accordingly, the first direction and the second direction can be adjusted with high accuracy.

  The vertical prism 7 is a prism in which a ridge 71 extending in a direction substantially perpendicular to the light incident surface 21a is repeatedly formed at a predetermined interval in a direction substantially parallel to the light incident surface 21a with respect to the light exit surface 21b. is there. The vertical prism 7 is a lenticular lens, and has a maximum tangent angle of 2 ° to 10 °.

  Therefore, according to the spread illuminating apparatus 1 according to the embodiment, light mixed in the first region and incident on the vertical prism 7 at an angle almost perpendicular to the vertical prism 7 is efficiently emitted from the surface of the vertical prism 7 as first mode light. Can be emitted. Further, light that passes through the first region substantially vertically and travels substantially parallel to the ridge 71 may be reflected inside the light guide plate 21 without being emitted from the light guide plate 21, and may be mixed without color unevenness. it can.

  In the spread illuminating apparatus 1 according to the embodiment, in the first region, the light traveling in the first direction is emitted from the vertical prism 7, and in the second region, the light whose optical path has been changed by the optical path changing unit. Is emitted.

  Therefore, according to the planar lighting device 1 according to the embodiment, the first mode light and the second mode light mixed by different mechanisms from the first region and the second region having different distances from the light incident surface 21a, respectively. Can be emitted, and the occurrence of color unevenness near the light incident surface 21a of the light guide plate 21 can be suppressed with a high degree of freedom, and both narrowing of the frame and widening of the color gamut can be achieved.

  Further, the vertical prism 7 travels in the first direction, and emits light incident at an angle smaller than the critical angle with respect to the direction in which the vertical prism 7 extends, from the vertical prism 7.

  Therefore, according to the surface illumination device 1 according to the embodiment, light that is mixed in the first region and that is incident on the vertical prism 7 at an angle substantially perpendicular to the surface is emitted from the surface of the vertical prism 7 as first mode light. be able to.

  In the above-described embodiment, the case where the vertical prism 7 or the light incident prism 8 is formed directly on the light exit surface 21b or the light incident surface 21a has been described as an example. However, the present invention is not limited to this. For example, by attaching a transparent sheet member having an irregular shape such as a vertical prism 7 or a light-entering prism 8 on the surface to the exit surface 21b or the light-entering surface 21a, the vertical prism 7 or the light-entering prism 8 is formed. May be provided.

  Further, in the above-described embodiment, the case where the light source 5 is an LED has been described as an example.

  Further, in the above-described embodiment, an example has been described in which the vertical prism 7 extends to the terminal surface of the light guide plate 21 (for example, the light incident surface 21a or the surface facing the light incident surface 21a). It is not necessary. Further, in the above-described embodiment, an example has been described in which the vertical prism 7 is provided on the emission surface 21b side and the optical path changing unit 6 is provided on the reflection surface 21c side. However, the vertical prism 7 is provided on the reflection surface 21c side. Alternatively, the optical path changing unit 6 may be provided on the emission surface 21b side.

  Further, the present invention is not limited by the above embodiments. The present invention also includes a configuration in which the above-described components are appropriately combined. Further, further effects and modified examples can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

  REFERENCE SIGNS LIST 1 planar illumination device, 2 emission areas, 3, 4 light shielding members, 5 light sources, 6 optical path changing section, 7 vertical prism (light diffusion section), 8 light input prism (light distribution section), 21 light guide plate, 21a light input Surface, 21b Emission surface, 21c Reflection surface, 71 convex stripe, 81, 82 Unit prism, 81a, 82a End surface (first end surface), 81b, 82b End surface (second end surface)

Claims (11)

A light guide plate having a side surface serving as a light incident surface and two main surfaces;
One including a plurality of light emitting elements having different emission colors, a plurality of light sources provided along the light incident surface;
A part of the light from the light source is provided on the light incident surface and travels in a first direction that is a direction close to a direction substantially parallel to the light incident surface, and the first direction of the light from the light source is A light distribution unit that causes light other than light that has traveled to travel in a second direction that is a direction substantially perpendicular to the light incident surface;
A light diffusing portion that extends in a direction substantially perpendicular to the light incident surface and is provided on one of the two main surfaces so as to have a continuous uneven shape in a cross section that intersects the extending direction; ,
An optical path changing unit that is provided on the other main surface of the two main surfaces and changes an optical path of light inside the light guide plate;
A planar lighting device comprising: The light distribution unit,
In the first region, which is a region near the light incident surface of the light guide plate and is a band-like region substantially parallel to the light incident surface, the light travels in the first direction;
The first region, and a region that is more distant from the light incident surface than the first region, and in a second region that is adjacent to the first region, causes light to travel in the second direction;
The planar lighting device according to claim 1. The light diffusion unit is provided from the first region to the second region,
The optical path changing unit is provided in the second area,
The planar lighting device according to claim 2. The light diffusion unit is provided from the first region to the second region,
The optical path changing unit is provided from the first area to the second area,
Almost all of the light whose optical path has been changed by the optical path changing unit provided in the first area is postponed to the second area.
The planar lighting device according to claim 2. The light diffusion unit,
It is provided on an emission surface that is a main surface for emitting light among the two main surfaces,
The optical path changing unit,
Provided on a reflection surface that is a main surface on the opposite side of the emission surface,
The spread illuminating device according to claim 2, 3 or 4. The optical path changing unit is a dot pattern,
Provided so that the distribution is more sparse in the first region than in the second region;
A spread illuminating device according to any one of claims 2 to 5. The light distribution unit is a prism,
A first end surface having an inclination angle substantially perpendicular to the light incident surface, and a second end surface having an inclination angle approximately parallel to the light incident surface;
The first end face is
Refracting light from the light source in the first direction,
The second end face,
Causing light from the light source to travel in the second direction;
A spread illuminating device according to claim 1. The light diffusion unit,
The ridges extending in a direction substantially perpendicular to the light incident surface are prisms repeatedly formed in a direction substantially parallel to the light incident surface at a predetermined interval with respect to the one main surface,
The spread illuminating device according to claim 1. The light diffusion unit is a lenticular lens, the maximum tangent angle is 2 ° to 10 °,
The planar lighting device according to claim 1. A light guide plate having a side surface serving as a light incident surface and two main surfaces;
One including a plurality of light emitting elements having different emission colors, a plurality of light sources provided along the light incident surface;
A part of the light from the light source is provided on the light incident surface and travels in a first direction that is a direction close to a direction substantially parallel to the light incident surface, and the first direction of the light from the light source is A light distribution unit that causes light other than light that has traveled to travel in a second direction that is a direction substantially perpendicular to the light incident surface;
A light diffusing portion that extends in a direction substantially perpendicular to the light incident surface and is provided on one of the two main surfaces so as to have a continuous uneven shape in a cross section that intersects the extending direction; ,
An optical path changing unit that is provided on the other main surface of the two main surfaces and changes an optical path of light inside the light guide plate;
With
In a first region, which is a region near the light entrance surface of the light guide plate, light traveling in the first direction is emitted from the light diffusion unit,
In the light guide plate, in a second region, which is a region farther from the light incident surface than the first region and adjacent to the first region, light whose light path has been changed by the light path changing unit is emitted. Is a spread illuminating device. The light diffusion unit,
Proceeding in the first direction, the light that has entered at an angle smaller than the critical angle with respect to the extending direction is emitted from the light diffusion unit,
The planar lighting device according to claim 10.

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