WO2022091870A1

WO2022091870A1 - Planar illumination device

Info

Publication number: WO2022091870A1
Application number: PCT/JP2021/038601
Authority: WO
Inventors: 正雄宮本; カイウ; 聡菅原
Original assignee: ミネベアミツミ株式会社
Priority date: 2020-11-02
Filing date: 2021-10-19
Publication date: 2022-05-05
Also published as: JPWO2022091870A1

Abstract

A planar illumination device (1) according to an embodiment comprises: a substrate (2); a light guide plate (4); an optical sheet (8); and light distribution control members (5, 6, and 9-11). A plurality of light sources (3) are two-dimensionally arranged on the substrate (2). The light guide plate (4) is disposed on a light-emission side of the substrate (2) and has a through-hole (4a) for accommodating the light sources (3) formed in the thickness direction. The optical sheet (8) is disposed on a light-emission side of the light guide plate (4) and has a light-blocking section (7) provided in a position overlapping the centers of the light sources (3) in plan view. The light distribution control members (5, 6, and 9-11) are arranged between the light guide plate (4) and the optical sheet (8) and/or on a light-emission side of the optical sheet (8).

Description

Planar lighting device

The present invention relates to a planar lighting device.

As a planar lighting device used as a backlight for a liquid crystal display device, a small light source such as an LED (Light Emitting Diode) is arranged two-dimensionally on a substrate, and an optical sheet is arranged directly below the light source. There is a type of planar lighting device (see, for example, Patent Documents 1 and 2).

In such a direct-type planar lighting device, since the light source is a point light source having directivity, the portion centered on the light source may become bright even through the optical sheet, resulting in uneven brightness (brightness). Deterioration of in-plane uniformity) is likely to occur.

The following methods are generally used to suppress such uneven brightness.
・ A method of arranging a large number of light sources to narrow the distance (pitch) between the light sources ・ A method of increasing the distance between the light sources and the optical sheet

International Publication No. 2006/107105 Japanese Unexamined Patent Publication No. 2010-277986

However, in the method of arranging a large number of light sources and narrowing the distance between the light sources, there is a problem that the number of LEDs and the like as the light sources increases, which leads to an increase in the cost of the planar lighting device. Further, the method of increasing the distance between the light source and the optical sheet has a problem that the thickness of the planar lighting device increases and the need for thinning cannot be met. As described above, there was a trade-off relationship between cost reduction by reducing the number of light sources and thinning.

The present invention has been made in view of the above, and an object of the present invention is to provide a planar lighting device capable of reducing luminance unevenness without increasing the number of light sources or the thickness of the device.

In order to solve the above-mentioned problems and achieve the object, the planar lighting device according to one aspect of the present invention includes a substrate, a light guide plate, an optical sheet, and a light distribution control member. A plurality of light sources are arranged two-dimensionally on the substrate. The light guide plate is arranged on the exit surface side of the substrate, and a through hole for accommodating the light source is provided in the thickness direction. The optical sheet is arranged on the emission surface side of the light guide plate, and a light-shielding portion is provided at a position overlapping the center of the light source in a plan view. The light distribution control member is arranged between the light guide plate and the optical sheet and / and on the emission surface side of the optical sheet.

The planar lighting device according to one aspect of the present invention can reduce luminance unevenness without increasing the number of light sources or the thickness of the device.

FIG. 1 is a plan view showing a configuration example of the planar lighting device according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line YY of the planar lighting device in FIG. 1, showing a configuration example of the first embodiment. FIG. 3 is a cross-sectional view taken along the line YY of the planar lighting device in FIG. 1, showing a configuration example of the second embodiment. FIG. 4 is a cross-sectional view taken along the line YY of the planar lighting device in FIG. 1, showing a configuration example of the third embodiment. FIG. 5 is a cross-sectional view corresponding to a YY sectional view of the planar illuminating device in FIG. 1, showing a configuration example of a planar illuminating device as a comparative example. FIG. 6A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet in the first embodiment. FIG. 6B is a diagram showing an example of the luminance distribution on the entire emission surface in the first embodiment. FIG. 7A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet in the second embodiment. FIG. 7B is a diagram showing an example of the luminance distribution on the entire emission surface in the second embodiment. FIG. 8A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet in the third embodiment. FIG. 8B is a diagram showing an example of the luminance distribution on the entire emission surface in the third embodiment. FIG. 9A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet in the comparative example. FIG. 9B is a diagram showing an example of the luminance distribution on the entire exit surface in the comparative example. FIG. 10 is an explanatory diagram of the function of the prism sheet in the third embodiment. FIG. 11 is an explanatory diagram of the function of the prism sheet in the second embodiment. FIG. 12 is a diagram showing an example of the intensity of the blue light emitted from the light source and the yellow light emitted from the phosphor sheet with respect to the distance from one end of the planar illuminating device. FIG. 13 is a plan view showing an example of the arrangement of the diffusion ring in the planar lighting device according to the fourth embodiment. FIG. 14 is a cross-sectional view taken along the line YY of the planar lighting device in FIG. FIG. 15 is a diagram showing an example of chromaticity values x and y in a central portion and a peripheral portion of a planar lighting device provided with a diffusion ring. FIG. 16 is a diagram showing an example of chromaticity values x and y in the central portion and the peripheral portion when there is no diffusion ring.

Hereinafter, the planar lighting device according to the embodiment will be described with reference to the drawings. The present invention is not limited to this embodiment. In addition, the relationship between the dimensions of each element in the drawing, the ratio of each element, etc. may differ from the reality. Even between the drawings, there may be parts where the relationship and ratio of the dimensions are different from each other. Further, in principle, the contents described in one embodiment or modification are similarly applied to other embodiments or modifications.

FIG. 1 is a plan view showing a configuration example of the planar lighting device 1 according to the first embodiment. Note that FIG. 1 is also common to the second embodiment and the third embodiment, which will be described later. FIG. 2 is a cross-sectional view taken along the line YY of the planar lighting device 1 in FIG. 1, showing a configuration example of the first embodiment. In addition, in FIGS. 1 and 2, the housing frame of the planar lighting device 1 is not shown.

In FIGS. 1 and 2, the planar lighting device 1 has a substantially rectangular planar shape, and a light guide plate 4,

prism sheets

5, 6 and phosphor sheets 8 and prism sheets 9 to 11 are sequentially arranged on a substrate 2. It has a laminated structure.

A light source 3 made of a plurality of LEDs or the like is arranged two-dimensionally on the substrate 2, and electrical wiring to each light source 3 is also provided. In the illustrated example, the light source 3 is assumed to emit blue light (blue light emitting diode), and is converted into white light by the phosphor sheet 8 in the subsequent stage. When the light source 3 emits white light (white light emitting diode), the phosphor sheet 8 becomes unnecessary.

Further, the lighting of the plurality of light sources 3 is controlled individually or in units of a plurality of groups by the control of so-called local dimming. Further, in order to improve the reflection of light, the surface of the substrate 2 on the side where the light source 3 is arranged (emission surface side) is painted white or the like, a reflective sheet is attached, or a reflective sheet is attached. It is desirable that the light source is placed, but there are cases where no special measures are taken against reflection.

The light guide plate 4 is laminated on the surface of the substrate 2 on the side where the light source 3 is arranged (exit surface side). The light guide plate 4 is made of a transparent resin such as polycarbonate, and a through hole 4a for a light source accommodating the light source 3 and a through hole 4b for a pseudo light source are provided in the thickness direction, respectively. The light guide plate 4 receives light from the light source 3 through the inner wall surface of the through hole 4a for the light source, passes through the inside, and then emits light to the outside from the through hole 4a for the light source and the through hole 4b for the pseudo light source. .. The through hole 4b for the pseudo light source emits light as if the light source is actually inside, except that the light from the light source is not directly emitted in the upward direction. Therefore, the pitch between the light sources can be narrowed without increasing the number of light sources 3 such as LEDs, and the in-plane uniformity of the brightness on the emission surface side can be improved.

Further, the light guide plate 4 may be composed of two or more light guide plates. In this case, it is desirable that the through holes for the light source overlap each other when viewed from the exit surface side, and the through holes for the pseudo light source do not overlap each other. As a result, the pitch between the light sources can be made narrower, and the in-plane uniformity of the luminance on the emission surface side can be further improved.

The prism sheet 5 is an optical sheet in which fine prisms having a pyramid shape or the like are formed on either or both of the light guide plate 4 side and the opposite side (exit surface side). The details of the function of the prism sheet 5 will be described later, but by providing the prism sheet 5 immediately after the emission surface side of the light guide plate 4, the light from the pseudo light source formed by the through hole 4b for the pseudo light source can be emitted. It is possible to raise the light in the direction perpendicular to the exit surface, increase the brightness in the vicinity of the through hole 4b for the pseudo light source, which tends to be dark, and improve the in-plane uniformity of light.

In the illustrated example, the prism sheet 6 is an optical sheet in which a fine prism having a pyramid shape or the like is formed on the light guide plate 4 side, and a through hole 4a of the light guide plate 4 is provided on the opposite side (exit surface side) in a plan view. A light-shielding portion 7 is formed by printing a white paint or the like at a position to be closed (a position overlapping the center of the light source 3). On the contrary, a light-shielding portion 7 may be provided on the light guide plate 4 side of the prism sheet 6, and a fine prism may be formed on the exit surface side. The outer shape of the light-shielding portion 7 as seen from the emission surface side is, for example, a circle. In addition to such a circle, a polygon such as an ellipse or a quadrangle may be used, or a pattern in which multiple straight lines such as x and * are crossed (increasing the degree of shading in the central part and surrounding the periphery). A pattern in which the degree of shading of the part is lowered) may be used.

The light-shielding unit 7 is composed of, for example, a single or a plurality of print layers. The light-shielding portion 7 includes light emitted directly from the light source 3 through the through hole 4a for the light source to the exit surface side, and light reflected from the light source 3 to the inner wall surface of the through hole 4a for the light source and emitted to the exit surface side. The light that penetrates the inner wall surface of the through hole 4a for the light source and is emitted to the emission surface side is blocked to reduce the uneven brightness. The light-shielding portion 7 does not have to have a light-shielding degree of 100%, and can be a light-shielding degree sufficient to reduce luminance unevenness. Further, each part of the light-shielding portion 7 does not have to have a uniform light-shielding degree, and for example, the light-shielding degree of the central portion can be increased and the light-shielding degree of the peripheral portion can be lowered. When composed of a plurality of print layers, the print layer having a large diameter and the print layer having a small diameter laminated on the print layer can increase the light-shielding degree in the central portion and lower the light-shielding degree in the peripheral portion. ..

As described above, the phosphor sheet 8 is excited by the blue light emitted from the light source 3 and emits white light. The prism sheets 9 to 11 are optical sheets in which fine prisms having a pyramid shape or the like are formed on either or both of the light guide plate 4 side and the opposite side (exit surface side). These prism sheets 9 to 11 further enhance the in-plane uniformity of luminance. The

prism sheets

5, 6, 9 to 11 constitute a light distribution control member.

FIG. 3 is a YY sectional view of the planar lighting device 1 in FIG. 1, showing a configuration example of the second embodiment. As mentioned above, FIG. 1 is also common to the second embodiment and the third embodiment. In FIG. 3, the difference from the configuration of the first embodiment of FIG. 2 is that the prism sheet 6 provided with the light-shielding portion 7 is changed to the flat sheet 12. The flat sheet 12 is a transparent sheet having both sides flat (flat). Although the details will be described later, the in-plane uniformity of the luminance is slightly inferior to that of the first embodiment of FIG. 2, but it has a sufficient effect. Further, as a modification of the second embodiment, two prism sheets 5 are used between the light guide plate 4 and the flat sheet 12, and another prism sheet 5 is used between the flat sheet 12 and the phosphor sheet 8. A prism sheet may be provided. In this case, the uniformity of brightness is improved by increasing the number of prism sheets.

FIG. 4 is a YY sectional view of the planar lighting device 1 in FIG. 1, showing a configuration example of the third embodiment. As mentioned above, FIG. 1 is also common to the second embodiment and the third embodiment. In FIG. 4, the configuration of the second embodiment of FIG. 3 is different from that of the prism sheet 5 provided between the light guide plate 4 and the flat sheet 12 between the flat sheet 12 and the phosphor sheet 8. It is a point that has come to be provided in. Although the details will be described later, the in-plane uniformity of the luminance is slightly inferior to that of the second embodiment of FIG. 3, but it has a sufficient effect.

FIG. 5 is a cross-sectional view corresponding to the YY cross-sectional view of the planar illuminating device 1 in FIG. 1, showing a configuration example of the planar illuminating device 1'as a comparative example. In FIG. 5, the configuration of the planar lighting device 1'is closest to that of the third embodiment of FIG. 4, in which the members having "'" in the same reference numeral correspond to the prism sheet 5 and the fluorescence. The positions of the body sheet 8 are interchanged as the prism sheet 5'and the phosphor sheet 8'. That is, the prism sheet 5'is provided between the phosphor sheet 8'and the prism sheet 9'. Other configurations are the same. In the comparative example, the substrate 2'to the flat sheet 12'and the light-shielding portion 7'are the basic light emitting units, and the phosphor sheet 8'for conversion to white light is placed on the light emitting unit. A prism sheet 5', 9', 10', 11'for adjusting the light distribution and brightness uniformity is placed on the structure.

Hereinafter, the simulation results regarding the brightness (luminance) of the first embodiment, the second embodiment, the third embodiment, and the comparative example are shown.

FIG. 6A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet 8 in the first embodiment (FIG. 2). FIG. 6B is a diagram showing an example of the luminance distribution on the entire emission surface (exit surface of the prism sheet 11) in the first embodiment (FIG. 2).

FIG. 7A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet 8 in the second embodiment (FIG. 3). FIG. 7B is a diagram showing an example of the luminance distribution on the entire emission surface (exit surface of the prism sheet 11) in the second embodiment (FIG. 3).

FIG. 8A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet 8 in the third embodiment (FIG. 4). FIG. 8B is a diagram showing an example of the luminance distribution on the entire emission surface (exit surface of the prism sheet 11) in the third embodiment (FIG. 4).

FIG. 9A is a diagram showing an example of the luminance distribution immediately before the phosphor sheet 8'in the comparative example (FIG. 5). FIG. 9B is a diagram showing an example of the luminance distribution on the entire emission surface (exit surface of the prism sheet 11') in the comparative example (FIG. 5).

The "brightness" shown at the bottom in FIGS. 6A, 7A, 8A and 9A is the total amount of light passing through the surface immediately before the phosphor sheets 8 and 8'. The "brightness" shown at the bottom in FIGS. 6B, 7B, 8B and 9B is the total amount of light passing through the exit surface of the prism sheets 11 and 11'. The "brightness ratio" is the ratio of the minimum value to the maximum value of the brightness of the light passing through the exit surface of the prism sheets 11 and 11'.

In FIGS. 6A, 7A, 8A and 9A, just before the phosphor sheets 8 and 8', the brightness of the comparative example of FIG. 9A is about 1840, whereas the brightness of FIG. 6A is about 1987. The brightness of FIG. 7A is about 1892, and the brightness of FIG. 8A is about 1702. Therefore, the first embodiment of FIG. 6A is the brightest, then the second embodiment of FIG. 7A is bright, and then the comparative example of FIG. 9A is bright. The third embodiment of FIG. 8A is darker than the comparative example.

Further, in FIGS. 6B, 7B, 8B and 9B, the brightness of the comparative example of FIG. 9B is about 890 on the exit surface of the prism sheets 11 and 11', whereas the brightness of FIG. 6B is about. 1178, the brightness of FIG. 7B is about 1137, and the brightness of FIG. 8B is about 943. Therefore, the first embodiment of FIG. 6B is the brightest, then the second embodiment of FIG. 7B is bright, then the third embodiment of FIG. 8B is bright, both of which are brighter than the comparative example of FIG. 9B.

Further, while the brightness ratio of the comparative example of FIG. 9B is 90.50%, the brightness ratio of FIG. 6B is 99.08% and the brightness uniformity is the highest, and the brightness ratio of FIG. 7B is 98.30% and the brightness uniformity is the next. The brightness ratio of FIG. 8B is 94.72%, which is the second highest brightness uniformity, and the brightness uniformity is higher than that of the comparative example of FIG. 9B. Therefore, it can be said that the first embodiment, the second embodiment, and the third embodiment are superior to the comparative example in terms of brightness and brightness ratio on the entire exit surface.

The reason why the brightness and the brightness ratio are better in the second embodiment of FIG. 3 than in the third embodiment of FIG. 4 will be described. FIG. 10 is an explanatory diagram of the function of the prism sheet 5 in the third embodiment (FIG. 4). FIG. 11 is an explanatory diagram of the function of the prism sheet 5 in the second embodiment (FIG. 3).

In FIG. 10, the light emitted from the through hole 4b for the pseudo light source of the light guide plate 4 passes through the flat sheet 12 and then is provided on one surface of the prism sheet 5 (upper surface in the illustrated example). It is raised in the direction perpendicular to the exit surface by the prism. In FIG. 10, since the prism sheet 5 is far from the pseudo light source by the thickness of the flat sheet 12, the light spread to some extent is launched.

On the other hand, in FIG. 11, the light emitted from the through hole 4b for the pseudo light source of the light guide plate 4 is immediately emitted by a fine prism provided on one surface (upper surface in the illustrated example) of the prism sheet 5. It is launched vertically. Therefore, the light is launched before the light from the pseudo light source spreads.

The vicinity of the through hole 4b for the pseudo light source tends to be dark because there is no actual light source, and the light that is launched in a spread state as shown in FIG. 10 has a low light density and tends to be dark. The brightness in the vicinity cannot be fully compensated. On the other hand, as shown in FIG. 11, the light that is started up without spreading has a higher density of light, and can sufficiently compensate for the brightness in the vicinity that tends to be dark. As a result, the brightness and the brightness ratio of the second embodiment are better than those of the third embodiment.

Next, measures for preventing the peripheral portion of the planar lighting device 1 from becoming bluish due to the combination of the light source 3 that emits blue light and the phosphor sheet 8 will be described.

FIG. 12 is a diagram showing an example of the intensity of the blue light BL emitted from the light source 3 and the yellow light YL emitted from the phosphor sheet 8 with respect to the distance from one end of the planar lighting device 1. be. In FIG. 12, the position P indicates the center of the light source 3 at the end, and the blue light BL has a steep characteristic of concentrating on the center. On the other hand, the yellow light YL emitted from the phosphor sheet 8 by the passage of the blue light BL tends to spread in a direction parallel to the emitting surface, and has a characteristic more gradual than that of the blue light BL.

In the central portion of the planar lighting device 1, the light amount balance is adjusted so that the blue light BL from the light source 3 is mixed with the yellow light YL transmitted from all directions around the light source 3 to produce white light. In the outer peripheral portion of 1, although the blue light BL from the light source 3 is the same, the yellow light YL is not transmitted from the side of the surrounding area where the light source 3 does not exist, so that the amount of yellow light YL is insufficient. However, the light is not sufficiently white and becomes bluish.

FIG. 13 is a plan view showing an example of the arrangement of the diffusion ring 15 in the planar lighting device 1 according to the fourth embodiment. FIG. 14 is a cross-sectional view taken along the line YY of the planar lighting device 1 in FIG.

In FIGS. 13 and 14, a diffusion ring 15 having a predetermined width is provided between the phosphor sheet 8 and the prism sheet 9 on the outer peripheral portion of the planar lighting device 1. The diffusion ring 15 diffuses or reflects a predetermined percentage of the irradiated light, and diffuses or transmits the rest. As the diffusion ring 15, a normal white print layer or the like is specifically assumed, but for example, a wavelength selection film having a higher reflectance of blue light than yellow light may be used. Alternatively, the white print layer and the wavelength selection film may be laminated. In the figure, the diffusion ring 15 extends from the end of the planar lighting device 1 to the middle of the first through hole 4a, but when it reaches the front of the through hole 4a or the first through hole. When it exceeds 4a (including the case where it exceeds a plurality of through holes 4a), the width is set so that the bluish chromaticity can be alleviated. Further, in FIG. 14, other configurations are the same as those in FIG. The diffusion ring 15 may be provided between the phosphor sheet 8 and the prism sheet 9 in FIGS. 3 and 4.

In FIG. 14, the blue light emitted from the light source 3 reaches the phosphor sheet 8 through the

prism sheets

5 and 6, and a part of the blue light is converted into yellow light. Further, a part of the blue light emitted from the light source 3 passes through the

prism sheets

5 and 6 and the phosphor sheet 8 and reaches the diffusion ring 15 on the outer peripheral portion, and a part of the blue light is diffusely reflected and reflected on the phosphor sheet 8. Return to the side. The blue light returned to the phosphor sheet 8 side is converted into yellow light again in the phosphor sheet 8, and a part of the blue light is transmitted to the prism sheet 9 side. Therefore, compared to the case without the diffuser ring 15, the yellow light diffusely reflected by the diffuser ring 15 and reconverted by the phosphor sheet 8 is added to the prism sheet 9 side, so that the bluish color due to the lack of yellow light is corrected. And get closer to the desired white light.

FIG. 15 is a diagram showing an example of chromaticity values x and y in the central portion and the peripheral portion of the planar lighting device 1 provided with the diffusion ring 15. FIG. 16 is a diagram showing an example of chromaticity values x and y in the central portion and the peripheral portion when there is no diffusion ring.

As is clear from FIGS. 15 and 16, the chromaticity values x and y in the central portion are x = 0.275 and y = 0.267, and there is no change, but the chromaticity values x and y in the outer peripheral portion are x in FIG. It is improved from = 0.245 and y = 0.227 to x = 0.260 and y = 0.241 in FIG.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

As described above, in the planar illumination device according to the embodiment, a substrate in which a plurality of light sources are arranged in two dimensions and a guide hole arranged on the exit surface side of the substrate and having through holes accommodating the light sources are provided in the thickness direction. An optical sheet arranged on the light emitting surface side of the light guide plate and a light-shielding portion provided at a position overlapping the center of the light source in a plan view, and between the light guide plate and the optical sheet and / or on the exit surface side of the optical sheet. It is provided with a light distribution control member to be arranged. This makes it possible to reduce luminance unevenness without increasing the number of light sources or the thickness of the device. In addition, the effect of improving the brightness is also recognized by these configurations.

Further, the light distribution control member is arranged between the light guide plate and the optical sheet. Thereby, the brightness and the uniformity of the brightness can be further improved.

Further, the optical sheet is composed of another light distribution control member. This makes it possible to further reduce the uneven brightness.

The light distribution control member is a prism sheet. Thereby, the light distribution control member can be easily realized.

When the light distribution control member is arranged between the light guide plate and the optical sheet, it is arranged on the emission surface side of the optical sheet, and when the light distribution control member is arranged on the emission surface side of the optical sheet. It includes a phosphor sheet and a plurality of other light distribution control members arranged on the emission surface side of the light distribution control member. As a result, even when a light source of blue light is used, white light can be emitted without uneven brightness.

It also includes a phosphor sheet and a plurality of other light distribution control members arranged on the emission surface side of the optical sheet. Thereby, the brightness and the uniformity of the brightness can be further improved.

It also has a diffusion ring arranged around the emission surface side of the phosphor sheet. As a result, even when a light source of blue light and a phosphor sheet are used, it is possible to prevent the peripheral portion from becoming bluish, and it is possible to improve the uniformity of chromaticity.

When the light distribution control member is arranged between the light guide plate and the optical sheet, it is arranged on the emission surface side of the optical sheet, and when the light distribution control member is arranged on the emission surface side of the optical sheet. It includes a plurality of other light distribution control members arranged on the emission surface side of the light distribution control member. As a result, the light can be emitted without uneven brightness.

Further, the light guide plate is provided with a through hole for a pseudo light source in the thickness direction around the through hole for accommodating the light source. This makes it possible to further reduce the uneven brightness.

Further, when the light guide plate is composed of one or more light guide plates and the light guide plate is composed of two or more light guide plates, the through holes accommodating the light source overlap each other when viewed from the exit surface side, and is used for a pseudo light source. The through holes do not overlap. This makes it possible to further reduce the uneven brightness.

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

1 planar lighting device, 2 substrate, 3 light source, 4 light guide plate, 4a, 4b through hole, 5, 6, 9-11 prism sheet, 7 shading part, 8 fluorescent sheet, 12 flat sheet, 15 diffusion ring

Claims

A board in which multiple light sources are arranged two-dimensionally,
A light guide plate arranged on the exit surface side of the substrate and having a through hole for accommodating the light source in the thickness direction.
An optical sheet arranged on the emission surface side of the light guide plate and provided with a light-shielding portion at a position overlapping the center of the light source in a plan view.
A light distribution control member arranged between the light guide plate and the optical sheet and / and on the emission surface side of the optical sheet.
A planar lighting device equipped with.
The light distribution control member is arranged between the light guide plate and the optical sheet.
The planar lighting device according to claim 1.
The optical sheet is composed of another light distribution control member.
The planar lighting device according to claim 1 or 2.
The light distribution control member is a prism sheet.
The planar lighting device according to any one of claims 1 to 3.
When the light distribution control member is arranged between the light guide plate and the optical sheet, it is arranged on the emission surface side of the optical sheet, and the light distribution control member is arranged on the emission surface side of the optical sheet. In this case, the light distribution control member is provided with a phosphor sheet and a plurality of other light distribution control members arranged on the emission surface side of the light distribution control member.
The planar lighting device according to any one of claims 1 to 4.
A phosphor sheet and a plurality of other light distribution control members arranged on the emission surface side of the optical sheet.
The planar lighting device according to claim 2.
A diffusion ring arranged in a peripheral portion on the emission surface side of the phosphor sheet is provided.
The planar lighting device according to claim 5 or 6.
When the light distribution control member is arranged between the light guide plate and the optical sheet, it is arranged on the emission surface side of the optical sheet, and the light distribution control member is arranged on the emission surface side of the optical sheet. In this case, a plurality of other light distribution control members are provided, which are arranged on the emission surface side of the light distribution control member.
The planar lighting device according to any one of claims 1 to 4.
The light guide plate is provided with a through hole for a pseudo light source in the thickness direction around the through hole accommodating the light source.
The planar lighting device according to any one of claims 1 to 8.
The light guide plate is composed of one or more light guide plates.
When the light guide plate is composed of two or more light guide plates, the through holes accommodating the light source overlap each other when viewed from the emission surface side, and the through holes for the pseudo light source do not overlap each other.
The planar lighting device according to claim 9.