WO2019117159A1

WO2019117159A1 - Lens and planar illumination device

Info

Publication number: WO2019117159A1
Application number: PCT/JP2018/045541
Authority: WO
Inventors: 英椋本; 銀河伊藤; 友晶森下
Original assignee: ミネベアミツミ株式会社
Priority date: 2017-12-15
Filing date: 2018-12-11
Publication date: 2019-06-20

Abstract

A lens according to an embodiment covers, in the emission direction, a plurality of point light-sources that are disposed in a row. The lens comprises: a main surface which is an emission surface; a plurality of recesses which are recessed from the main surface toward the rear surface in the thickness direction, at positions corresponding to the point light-sources; and a reflection part that causes light reflected from the main surface to the rear surface side to be reflected back to the main surface side.

Description

Lens and planar lighting device

The present invention relates to a lens and a surface illumination device.

In recent years, there is a planar illumination device that illuminates a display panel of a liquid crystal display device from the back side. A planar illumination device is roughly classified into an edge light type and a direct type. Further, in the planar illumination device, so-called local dimming (area light emission) -compliant planar illumination device capable of adjusting the brightness for each area of the light emitting surface by controlling the light quantity of each point light source. It has been known.

In addition, a direct type planar illumination device compatible with local dimming (area light emission) includes a lens for diffusing light emitted from a point light source, and spreads out light from the point light source to emit light, whereby the brightness of each area is obtained. It can be made uniform.

JP, 2010-8837, A

However, due to the recent demand for thinning the planar illumination device, it has become impossible to ensure sufficient uniformity of luminance. For example, in the case of using a planar illumination device as a backlight of an information display of a vehicle, the installation space is limited, and in order to ensure uniform brightness, it is not possible to meet the demand for thinning.

This invention is made in view of the above, Comprising: It aims at providing the lens and planar illumination device which can improve the uniformity of luminosity.

In order to solve the problems described above and to achieve the object, a lens according to an aspect of the present invention is a lens that covers point light sources arranged in a row from an emission direction, and a main surface that is an emission surface; The back surface facing the main surface, a plurality of recesses recessed in the thickness direction from the main surface toward the back surface at a position corresponding to a point light source, and the light reflected from the main surface toward the back surface And a reflecting portion that reflects light to the side.

According to one embodiment of the present invention, the uniformity of luminance can be improved.

FIG. 1: is a top view which shows an example of the external appearance of the planar illuminating device which concerns on embodiment. FIG. 2 is a top view showing an exemplary arrangement of lenses. FIG. 3A is a schematic cross-sectional view (No. 1) along the line AA shown in FIG. FIG. 3B is a schematic cross-sectional view (No. 2) along the line AA shown in FIG. FIG. 4 is a top view of the lens according to the first embodiment. FIG. 5A is a schematic cross-sectional view taken along the line BB shown in FIG. FIG. 5B is a schematic cross-sectional view along the line BB shown in FIG. FIG. 6 is a schematic view showing light distribution characteristics of the lens according to the first embodiment. FIG. 7 is a diagram showing the comparison result of the luminance distribution according to the presence or absence of the transmission part. FIG. 8 is a top view showing an arrangement example of lenses according to the second embodiment. FIG. 9 is a schematic cross-sectional view taken along the line CC shown in FIG. FIG. 10 is a schematic cross-sectional view of a lens according to a third embodiment. FIG. 11 is a perspective view of the lens according to the third embodiment as viewed from the back surface side. FIG. 12 is a view showing light distribution characteristics of the lens according to the third embodiment. FIG. 13A is a schematic cross-sectional view (No. 1) of a lens according to a fourth embodiment. FIG. 13B is a schematic cross-sectional view (No. 2) of the lens according to the fourth embodiment. FIG. 14 is a perspective view of the lens according to the fourth embodiment as viewed from the back side. FIG. 15 is a view showing the light distribution characteristic of the lens according to the fourth embodiment. FIG. 16 is a diagram (part 1) illustrating a simulation result of the lens according to the fourth embodiment. FIG. 17 is a second diagram showing a simulation result of the lens according to the fourth embodiment. FIG. 18 is a diagram (part 1) showing a modification of the buttocks. FIG. 19 is a second diagram showing a modification of the buttocks. FIG. 20 is a top view of a reflector according to the fifth embodiment. FIG. 21 is a schematic cross-sectional view taken along the line DD shown in FIG. FIG. 22 is a perspective view of the lens according to the fifth embodiment as viewed from the back surface side. FIG. 23 is a view showing light distribution characteristics of a reflector and a lens according to the fifth embodiment. FIG. 24 is a diagram (part 1) illustrating the comparison result of the luminance distribution according to the presence or absence of the frame portion according to the fifth embodiment. FIG. 25 is a second diagram showing the comparison result of the luminance distribution according to the presence or absence of the frame portion according to the fifth embodiment. FIG. 26 is a third diagram showing a comparison result of luminance distribution according to the presence or absence of a frame portion according to the fifth embodiment. FIG. 27 is a perspective view of the back surface side of the lens according to the sixth embodiment. FIG. 28 is a bottom view of the substrate according to the sixth embodiment. FIG. 29 is a schematic view (No. 1) showing a fixing aspect of the lens and the substrate according to the sixth embodiment. FIG. 30 is a schematic view (No. 2) showing a fixing aspect of the lens and the substrate according to the sixth embodiment. FIG. 31 is a schematic view (No. 3) showing a fixing aspect of the lens and the substrate according to the sixth embodiment. FIG. 32 is a schematic cross-sectional view of the planar illumination device according to the first modification. FIG. 33: is a cross-sectional schematic diagram of the planar illuminating device which concerns on a 2nd modification.

Hereinafter, a lens and a planar illumination device according to an embodiment will be described with reference to the drawings. Note that the present invention is not limited by the embodiments described below. In addition, the dimensional relationships among the elements in the drawings, the proportions of the elements, and the like may differ from reality. In addition, parts having different dimensional relationships and ratios may be included among the drawings.

First, the outline of the planar illumination device according to the embodiment will be described with reference to FIG. FIG. 1: is a front view which shows an example of the external appearance of the planar illuminating device which concerns on embodiment. The planar illumination device 1 according to the present embodiment is a direct-type planar illumination device, and is used as a backlight of various liquid crystal display devices. Such a liquid crystal display device is, for example, an electronic speedometer of a vehicle, but is not limited thereto.

As shown in the example of FIG. 1, the planar illumination device 1 according to the embodiment emits light from an emission area not covered by the frame 10. The connector C is connected with power supply wiring, signal wiring, and the like. That is, the planar illumination device 1 according to the embodiment is supplied with power and signals via the connector C.

By the way, in general, in a direct type planar illumination device, a plurality of point light sources are arranged in a grid, and a lens is provided for each point light source and a lens is provided for each of a plurality of point light sources arranged in a row. There is.

The lens according to the present embodiment is applicable to both cases. First, the case where a lens is provided for each point light source will be described as the first embodiment. FIG. 2 is a top view showing the arrangement of lenses according to the first embodiment. In addition, in order to clarify the positional relationship of the lens 50 and the point light source 30, in FIG. 2, the point light source 30 is shown collectively.

As shown in FIG. 2, the point light sources 30 are arranged in a grid. Each point light source 30 is provided with a lens 50 from the emission direction. That is, in the planar illumination device 1, since the point light sources 30 are arranged in a grid, the lenses 50 are also arranged in a grid.

Next, an internal configuration of the spread illuminating apparatus 1 according to the first embodiment will be described using FIGS. 3A and 3B. FIG. 3A and FIG. 3B are schematic cross sections along the line AA shown in FIG. As shown in FIG. 3A, the planar illumination device 1 according to the embodiment includes the frame 10, the substrate 20, the point light source 30, the reflection plate 40, the lens 50, the diffusion plate 60, the spacer 70, and optics. A seat 80 and an elastic member 90 are provided.

The frame 10 is a sheet metal frame having high rigidity, for example, stainless steel, and accommodates the respective members of the planar illumination device 1. Also, the frame 10 includes, for example, an upper frame 11 and a lower frame 12.

The upper frame 11 is disposed on the upper surface side of the lower frame 12. The upper frame 11 has a rectangular top plate 11 a having an opening formed at its central portion, and a side wall 11 b extending from the periphery of the top plate 11 a along the outer surface of the lower frame 12. The lower frame 12 has a rectangular bottom 12 a and a side wall 12 b extending from the periphery of the bottom 12 a along the inner side of the upper frame 11.

The substrate 20 is made of, for example, an epoxy resin or PI (polyimide), and has a main surface on which a plurality of point light sources 30 are mounted in a lattice. The point light source 30 is, for example, a light emitting diode (LED). The point light source 30 is disposed on the substrate 20 such that the optical axis is substantially perpendicular to the lens 50.

The reflection plate 40 is formed of, for example, a white resin or the like. The reflecting plate 40 reflects the light reflected by the lens 50 toward the reflecting plate 40 toward the lens 50 again. Thus, the emission efficiency can be improved. In addition, about the structure of the reflecting plate 40, it mentions later using attached drawing after FIG.

The lens 50 performs light distribution control of light emitted from the point light source 30. The lens 50 has a rectangular or substantially rectangular outer shape in top view. As a material of the lens 50, for example, PMMA (polymethyl methacrylate) or polycarbonate can be used, but it is not limited thereto. The light whose light distribution is controlled by the lens 50 is emitted to the diffusion plate 60. The lens 50 also has a leg 55 that protrudes toward the substrate 20. For example, in the lens 50, an adhesive member such as an adhesive is applied to the bottom of the leg 55, for example, and fixed to the substrate 20, but the fixing method is not limited thereto. The details of the lens 50 will be described later with reference to FIG. 4 and subsequent drawings.

The diffusion plate 60 is made of a material such as resin and has a function of diffusing the light emitted from the lens 50. That is, the light emitted from the lens 50 is diffused by the diffusion plate 60 and guided to the optical sheet 80.

The spacer 70 is disposed between the lens 50 and the diffusion plate 60, and keeps the distance between the lens 50 and the diffusion plate 60 constant. The material of the spacer 70 is not particularly limited. For example, the spacer 70 may be formed of a white resin and have a function of reflecting light emitted from the lens 50. The spacer 70 presses the diffusion plate 60 from the lower surface side along the longitudinal direction (X axis) of the planar illumination device 1, and presses the lens 50 from the upper surface side along the longitudinal direction. The spacer 70 may not necessarily hold the distance between the lens 50 and the diffusion plate 60 in the lateral direction (Y axis) of the planar illumination device 1.

The optical sheet 80 performs optical adjustment such as equalization and light distribution control on the light emitted from the diffusion plate 60, and emits the light subjected to the optical adjustment. In the example shown to FIG. 3A, it is illustrated about the case where the optical sheet 80 is comprised by two sheets, the 1st sheet 81 and the 2nd sheet 82. As shown in FIG.

For example, the first sheet 81 is, for example, BEF (Brightness Enhancement Film) manufactured by 3M, and the second sheet 82 is, for example, DBEF (Dual Brightness Enhancement Film) manufactured by 3M. It is possible to change arbitrarily according to the light emission aspect calculated | required. The optical sheet 80 is fixed to the exit surface of the diffusion plate 60 by, for example, an adhesive or an adhesive member such as a double-sided tape.

The elastic member 90 is a frame-like member having elasticity, such as rubber or sponge. The elastic member 90 is provided on the optical sheet 80, holds the diffusion plate 60 and the optical sheet 80 between the spacer 70 and holds the same, and presses the lens 50 through the spacer 70 by its elastic force. In addition, when vibration occurs in the planar lighting device 1, the elastic member 90 absorbs the vibration. The elastic member 90 is disposed between the upper frame 11 and the diffusion plate 60, and presses the diffusion plate 60 from the top plate side of the upper frame 11. The elastic member 90 is not limited to the frame shape, and for example, a plurality of rod-like elastic members having a rectangular cross-sectional shape may be used.

Further, as shown in FIG. 3B, the elastic member 90 may be provided so as to avoid the upper surface of the optical sheet 80. Specifically, as shown in FIG. 3B, the elastic member 90 is installed on the upper surface of the diffusion plate 60, and is pressed toward the diffusion plate 60 by the top plate 11a. Also, the optical sheet 80 is installed on the side surface of the elastic member 90. In such a case, the optical sheet 80 is smaller than the diffusion plate 60 in top view, and the elastic member 90 is provided in a region where the optical sheet 80 does not cover the diffusion plate 60. Accordingly, it is possible to suppress the wrinkles of the optical sheet 80 when the planar illumination device 1 is manufactured or when the planar illumination device 1 vibrates.

Subsequently, the lens 50 according to the first embodiment will be described with reference to FIG. FIG. 4 is a top view of the lens 50 according to the first embodiment. In FIG. 4, the point light source 30 is also shown in order to clarify the positional relationship between the lens 50 and the point light source 30.

As shown in FIG. 4, the exit surface 51 of the lens 50 has a flat portion 57, a transmission portion 52, and a recess 53. The flat portion 57 is a flat surface provided continuously with the recess 53 and emits light to the diffusion plate 60. The transmitting portion 52 has a function of promoting the emission of light to the boundary with the adjacent lens 50. The transmitting portion 52 may be a transmitting portion recessed in the thickness direction of the lens 50, and the shape thereof is not particularly limited.

Specifically, as shown in FIG. 4, the transmitting portion 52 is formed concentrically at the outer peripheral portion of the recess 53, and is provided in contact with each side of the emission surface 51. That is, the transmitting portion 52 is provided on the outer peripheral portion of the emission surface 51. The transmitting portion 52 is a linear protrusion having a straight line or a curved line in a cross section and protruding from the emission surface. The transmitting unit 52 refracts and transmits a part of the emitted light, and promotes the emission of the light to the boundary with the adjacent lens 50. The transmitting portion 52 is not limited to the concentric shape, and may be formed in a linear shape as long as the transmitting portion 52 is formed on the outer peripheral portion of the emission surface 51. In the present embodiment, the boundary of the lens is the area above the gap with the adjacent lens 50, and it is difficult for the light from the point light source 30 to reach and the area easily darkens when the point light source 30 is lit. It is.

The recess 53 has a shape that is recessed in the thickness direction from the emission surface 51 immediately above the point light source 30 of the emission surface 51. In other words, the concave portion 53 is provided at a position corresponding to the point light source 30 of the light emission surface 51, and the concave portion 53 is a shape recessed from the light emission surface 51 toward the back surface 54. It is formed in a conical shape (or a weir shape). The concave portion 53 has a function of reflecting the light emitted from the point light source 30 to the back surface 54 side. In the recess 53, it is not necessary to reflect all the light emitted from the point light source 30 to the back surface 54 side, and there may be light transmitted from the recess 53 to the diffusion plate 60.

As described above, the recess 53 reflects the light emitted from the point light source 30 toward the back surface 54 side. The light intensity of the incident light is strong directly above the point light source 30 of the exit surface 51, but by reflecting most of the light emitted from the point light source 30 by the recess 53 toward the back surface 54, the light intensity directly above the point light source 30 Can be reduced. In other words, by reflecting the light from the point light source 30 by the concave portion 53, it is possible to suppress the increase in the luminance of the region corresponding to the portion immediately above the point light source 30 of the lens 50.

As described above, the light distribution of the light emitted from the point light source 30 is controlled so that the light intensity becomes uniform on the light emission surface 51. In other words, the lens 50 can equalize the luminance by dispersing the light incident immediately above the light source having high light intensity over the entire emission surface 51.

Subsequently, the cross-sectional shape of the lens 50 according to the embodiment will be described with reference to FIGS. 5A and 5B. 5A and 5B are schematic cross sections along the line BB shown in FIG. As shown in FIG. 5A, the lens 50 has a reflective portion 56 on the back surface 54 in addition to the transmissive portion 52 and the concave portion 53 formed on the output surface 51.

The reflective portion 56 is a dot protruding from the back surface 54 in the thickness direction of the lens 50, and is uniformly formed on the entire back surface 54, for example. The reflection unit 56 reflects the light reflected to the back surface 54 side at the emission surface 51 again to the emission surface 51 side.

That is, the reflection unit 56 reflects the light reflected to the back surface 54 side again to the emission surface 51 side by the concave portion 53 provided at the position corresponding to the point light source 30 of the lens 50. Thereby, the light reflected by the reflection part 56 is emitted to the diffusion plate 60 from the flat part 57 provided continuously to the concave part 53 of the lens 50. The reflecting portion 56 may have a dot shape which is recessed from the back surface 54 in the thickness direction of the lens 50. Also, the reflective portion 56 is not limited to dots.

5A shows the case where the transmitting portion 52 has a triangular shape and the reflecting portion 56 has a dot shape in a cross sectional view, the present invention is not limited to this, and as shown in FIG. 5B, the transmitting portion 52 However, the cross-sectional view may have a rounded shape such as a semicircular shape or a round shape, or the reflecting portion 56 may have a triangular shape.

Further, for the purpose of reducing color unevenness, the entire surface of the output surface 51 may be roughly processed, for example, by sand blasting or embossing, or dots may be provided on the entire output surface 51.

Subsequently, the light distribution characteristic of the lens 50 will be described with reference to FIG. FIG. 6 is a schematic view showing light distribution characteristics of the lens 50 according to the first embodiment. In FIG. 6, the optical path of light is indicated by a broken line.

As shown in FIG. 6, the light emitted from the point light source 30 is reflected by the recess 53 toward the back surface 54 as described above. Subsequently, the light is reflected again to the emission surface 51 side by the reflection portion 56 provided on the back surface 54. Then, the light reflected by the reflection unit 56 is emitted from the flat portion 57 of the emission surface 51. That is, the light emitted from the point light source 30 is guided within the lens 50, converted to substantially surface light emission, and emitted. Further, a part of the outgoing light is refracted and transmitted by the transmission part 52, and the outgoing light is promoted to the boundary with the adjacent lens 50.

As described above, in the lens 50 according to the first embodiment, the light distribution is controlled so that the light incident from the point light source 30 is uniformly emitted from the entire emission surface 51. That is, according to the lens 50 which concerns on this embodiment, equalization | homogenization of brightness | luminance can be improved.

Further, in the lens 50 according to the first embodiment, by refracting and transmitting a part of light by the transmitting unit 52, it is possible to suppress the light guided to the adjacent lens 50. In other words, the transmitting portion 52 can suppress the leakage of light to the adjacent lens 50. That is, the lens 50 according to the first embodiment can also improve the contrast when the point light sources 30 are individually lit by suppressing the light guided to the adjacent lens 50.

Next, the comparison result by the presence or absence of the lens 50 which concerns on embodiment using FIG. 7 is demonstrated. FIG. 7 is a view showing the comparison result of the luminance distribution according to the presence or absence of the transmission part 52. In addition, in FIG. 7, the simulation result of the luminance distribution at the time of making nine point light sources 30 emit light is shown. The circled area in FIG. 7 corresponds to the boundary between the lens 50 and the lens 50 adjacent to the lens 50.

Comparing the circled area shown in FIG. 7 with the presence or absence of the transmission part 52, it can be seen that the luminance is improved more in the case of the transmission part 52 than in the case of the absence of the transmission part 52.

That is, in the planar illumination device 1 according to the embodiment, by providing the transmitting portion 52 on the outer peripheral portion of the emission surface 51 of the lens 50, the brightness between the adjacent lenses 50 can be improved.

In other words, uneven brightness between adjacent lenses 50 can be suppressed. Therefore, according to the lens 50 which concerns on embodiment, equalization | homogenization of brightness | luminance can be improved.

As described above, in the lens 50 according to the embodiment, the reflecting portion 56 is provided on the back surface 54 which is the main surface facing the point light source 30 and is a main surface facing the back surface 54 from the output surface 51 to the back surface 54 side. Is reflected to the side of the exit surface 51. The recess 53 has a shape that is recessed in the thickness direction from the emission surface 51 immediately above the point light source 30. The transmitting portion 52 is provided on the outer peripheral portion of the recess 53, and refracts and transmits a part of light. As a result, the transmission portion 52 promotes emission of light to the boundary with the adjacent lens 50, the luminance between the adjacent lenses 50 is improved, and the luminance becomes uniform. Furthermore, the light leakage to the adjacent lens 50 is suppressed by the transmission part 52, and the contrast when the point light sources 30 are individually lit is improved. Therefore, according to the lens 50 according to the first embodiment, it is possible to improve the contrast when the point light sources 30 are individually lit while improving the uniformity of the luminance of the planar illumination device 1.

Second Embodiment
Next, a lens 50B according to a second embodiment will be described using FIGS. 8 to 9. FIG. In the second embodiment, the case where the lens 50B covers a plurality of point light sources 30 alone will be described.

First, an outline of the lens 50B according to the second embodiment will be described with reference to FIG. FIG. 8 is a top view showing an arrangement example of the lens 50B according to the second embodiment. As shown in FIG. 8, the lens 50 B according to the second embodiment differs from the lens 50 according to the first embodiment in that it covers a plurality of point light sources 30.

Specifically, the lens 50B according to the second embodiment covers a plurality of point light sources 30 lined in the short direction (Y axis) among the plurality of point light sources 30 lined in a grid-like manner alone, They are arranged in parallel along the direction (X axis). The lens 50B is rectangular or substantially rectangular in top view. The lens 50B according to the present embodiment has a rectangular shape in which the side extending in parallel to the short direction (Y axis) is a long side and the side extending in a direction parallel to the longitudinal direction (X axis) is a short side in top view is there.

Thus, by covering the plurality of point light sources 30 aligned in the short direction, the lens 50B can shorten the lens length as compared to the case of covering the plurality of point light sources 30 aligned in the longitudinal direction.

This is because the lens 50B thermally expands (contracts) due to the heat generation of the point light source 30 and the ambient environment temperature, and the lens 50B is caused by positional deviation between the point light source 30 and the lens 50B due to the thermal expansion of the lens 50B. In order to suppress the deterioration of the optical characteristics of Assuming that the expansion coefficient per unit volume of the lens 50B is the same, the longer the lens length, the larger the expansion (contraction) volume, and the lens 50B expands (or shrinks) significantly.

Further, as will be described later with reference to FIG. 9, the light emitting surface 51 is provided with a recess 53 provided at a position corresponding to the immediate upper part of the point light source 30 and a transmitting part 52 between adjacent point light sources 30. The recess 53 and the transmission part 52 are designed based on the position of the point light source 30.

When the relative position between each point light source 30 and the transmitting portion 52 or the recess 53 is deviated, the light distribution characteristic of the light emitting surface 51 or the recess 53 is degraded. That is, the lens 50B according to the second embodiment covers the point light sources 30 arranged in the short direction so that the lens length is relatively short, whereby the positional deviation between each point light source 30 and the transmission part 52 or the recess 53 is obtained. Suppress. As a result, it is possible to suppress a decrease in light distribution characteristics due to thermal expansion or thermal contraction of the lens 50B.

Further, as shown in FIG. 8, the lens 50 B covers a row of point light sources 30. As a result, the width (length in the X-axis direction) of the lens 50B can be reduced, so that the lens 50B can be applied to the planar illumination device 1 having a curved exit surface.

Subsequently, a schematic cross-sectional view of the lens 50B according to the second embodiment will be described with reference to FIG. FIG. 9 is a schematic cross-sectional view taken along the line CC shown in FIG. As shown in FIG. 9, in the lens 50B according to the second embodiment, a plurality of transmitting portions 52, a plurality of recessed portions 53, and a flat portion 57 are formed on the emission surface 51b.

The transmitting portion 52 is provided around the recess 53. For example, in a cross sectional view, the transmitting portion 52 is provided in the boundary area between the corresponding point light source 30 and the point light source 30 adjacent to the point light source 30. In the lens 50 B according to the present embodiment, the transmitting portion 52 is a protrusion which has a straight line or a curved line in a cross section and which protrudes from the output surface 51. Moreover, the transmission part 52 which concerns on this embodiment is arranged in the direction substantially orthogonal to the arrangement direction of the point light source 30 which the lens 50B covers. In other words, the transmission part 52 is formed along the longitudinal direction (X axis). In addition, the concave portion 53 is provided at a position corresponding to the immediate upper part of the corresponding point light source 30 and has a shape that is recessed from the emission surface 51 toward the back surface 54. In the lens 50B according to the second embodiment, the back surface 54 is formed flat, and the reflecting portion 56 is uniformly formed on the entire surface.

That is, the lens 50B according to the second embodiment reflects the light emitted from the plurality of point light sources 30 toward the back surface 54 by the corresponding concave portions 53, and causes the light to be reflected again by the reflecting portion 56. Then, the light is emitted from the flat portion 57 of the emission surface 51.

As described above, in the lens 50B according to the second embodiment, the concave portion 53 is formed at a position corresponding to each point light source 30, and the transmission portion 52 is formed in the boundary region with the point light source 30 adjacent to each other. The transmitting unit 52 refracts and transmits a part of the emitted light and promotes the emission of light to the boundary with the adjacent emission surface 51, as in the transmitting unit 52 according to the first embodiment. Thereby, even in the case of covering a plurality of point light sources, it is possible to improve the brightness of the boundary portion of the emission surface 51. That is, as in the lens 50 according to the first embodiment, it is possible to improve the uniformity of the luminance. Furthermore, the light guided to the side of the light emitting surface 51 adjacent to the light transmission portion 52 is suppressed (for example, the light guiding to the light emitting surface 51-2 side adjacent to the light emitting surface 51-1 shown in FIG. 9 is suppressed) . In other words, the transmission portion 52 suppresses the leakage of light to the adjacent emission surface 51. Thereby, when the point light sources 30 are individually lit, it is possible to improve the contrast. In the present embodiment, the boundary portion of the lens is a region above the boundary region of the emission surface 51, and it is a region where light from the point light source 30 is hard to reach and is likely to be dark when the point light source 30 is lit. is there. As in the first embodiment, also in the lens 50B, the entire surface of the emission surface 51 may be roughly processed by sandblasting or embossing, or dots may be provided on the entire emission surface 51, for example.

Third Embodiment
Next, a lens 50C according to the third embodiment will be described with reference to FIGS. FIG. 10 is a schematic cross-sectional view of the lens 50C according to the third embodiment, which corresponds to the cross-sectional view along the line BB shown in FIG. FIG. 11 is a perspective view of the lens 50C according to the third embodiment as viewed from the back surface 54 side. FIG. 12 is a view showing light distribution characteristics of the lens 50C according to the third embodiment.

The lens 50C according to the third embodiment is a lens that covers one point light source 30 alone as in the lens 50 according to the first embodiment. The lens 50C according to the third embodiment is different in that the shapes of the lens 50 according to the first embodiment shown in FIG. 4 and the back surface 54 are different.

The lens 50C according to the third embodiment includes a transmitting portion 52, a concave portion 53, and a flat portion 57 on the emission surface 51, and a reflecting portion 56 on the back surface 54. In addition, the lens 50C according to the third embodiment protrudes from the end of the back surface 54 in the shape of a bowl toward the center, and such a bowl-shaped tip is formed in a flat shape, for example.

More specifically, as shown in FIG. 11, the back surface 54 has an inclined portion 59 which is inclined from the respective end sides of the ridge toward the center. Moreover, in the example shown in FIG. 11, in the back surface 54, although the front-end | tip of a ridge is a substantially plane, it is not limited to this. For example, such a tip may be dome-shaped or the like. Further, in the example shown in FIG. 11, the case where the back surface 54 is formed in a pyramid shape in the lens 50C according to the third embodiment is shown, but it is not limited to this.

Subsequently, the light distribution characteristic of the lens 50C according to the third embodiment will be described with reference to FIG. In addition, in FIG. 12, in order to simplify description, description of the transmissive part 52 and the reflection part 56 is abbreviate | omitted.

As shown in FIG. 12, the light emitted from the point light source 30 enters the lens 50C from the back surface 54. Subsequently, the light incident on the lens 50C is reflected by the concave portion 53 to the back surface 54 side. At this time, such light enters the inclined portion 59 at a predetermined incident angle. Thereby, the light reflected to the back surface 54 side by the output surface 51 is reflected again to the output surface 51 side by the inclined portion 59.

That is, the lens 50C according to the third embodiment promotes total reflection by the inclined portion 59 by providing the inclined portion 59 on the back surface 54. That is, the inclined portion 59 suppresses transmission of light from the back surface 54 to the point light source 30 side. Thereby, the lens 50C according to the third embodiment can improve the emission efficiency and the luminance. Further, the inclined portion 59 can prevent light from leaking to the adjacent lens 50C. Therefore, the lens 50C according to the third embodiment can also improve the contrast when the point light sources 30 are individually lit. It is.

As described above, the lens 50 C according to the third embodiment further includes the transmitting portion 52 on the emission surface 51 and the reflecting portion 56 on the back surface 54. The transmitting unit 52 refracts and transmits a part of the emitted light, thereby promoting the emission of light to the boundary with the adjacent lens 50C. The reflection unit 56 suppresses the emission of light from the back surface 54 and reflects the light toward the emission surface 51.

That is, in the lens 50C according to the third embodiment, by providing the inclined portion 59 in addition to the reflective portion 56 on the back surface 54, light is reflected toward the emission surface 51 in both the reflective portion 56 and the inclined portion 59. Do.

As a result, the lens 50C according to the third embodiment can improve the uniformity of luminance similarly to the

lenses

50 and 50B according to the first and second embodiments. The lens 50C according to the third embodiment can suppress the leakage of light from the back surface 54 and the light guided to the adjacent lens 50C by the inclined portion 59. Therefore, the emission efficiency can be improved and the luminance can be made uniform. Furthermore, it becomes possible to improve the contrast when the point light sources 30 are individually turned on.

Fourth Embodiment
Next, a lens 50D according to a fourth embodiment will be described. 13A and 13B are schematic cross-sectional views of a lens 50D according to a fourth embodiment. The schematic sectional views shown in FIGS. 14A and 14B correspond to the schematic sectional views taken along the line CC shown in FIG. As shown in FIG. 14A, the shapes of the lens 50B and the back surface 54 already described in FIG. 9 are different. The lens 50D has a transmitting portion 52, a concave portion 53, and a flat portion 57 on the emission surface 51, and a reflecting portion 56 on the back surface 54.

The transmitting portion 52 is a linear protrusion having a straight line or a curved line in cross section and protruding from the output surface 51 (the flat portion 57). The transmitting unit 52 has a function of refracting and transmitting a part of the emitted light. As shown in FIG. 13A, the transmitting portion 52 is in a triangular shape in a cross sectional view, but is not limited to this. For example, as shown in FIG. 13B, the transmitting portion 52 may have a rounded shape such as a semicircular or semicylindrical shape in a cross sectional view. In addition, the transmitting portions 52 are arranged in a direction substantially orthogonal to the arrangement direction of the point light sources 30 covered by the lens 50D.

As described above, since the lens 50D according to the embodiment covers the plurality of point light sources 30 along the short direction, the transmission part 52 is formed along the longitudinal direction. In the lens 50D according to the embodiment, by providing the transmitting portion 52 in the boundary area of the output surface 51, it is possible to accelerate the emission of light to the boundary with the adjacent output surface 51. This makes it possible to improve the brightness between the adjacent lenses 50D and to make the brightness uniform. Here, the boundary portion of the emission surface 51 is a region above the boundary region, and is a region where the light from the point light source 30 is difficult to reach and is likely to be dark when the point light source 30 is lit.

The recess 53 has a shape that is recessed in the thickness direction from the emission surface 51 immediately above the point light source 30 of the emission surface 51. In other words, the concave portion 53 is provided at a position corresponding to the point light source 30 of the light emission surface 51, and the concave portion 53 is a shape recessed from the light emission surface 51 toward the back surface 54. It is formed in an inverted conical shape (or a weir shape). The concave portion 53 has a function of reflecting the light incident from the point light source 30 to the back surface 54 side. In the recess 53, it is not necessary to reflect all the light emitted from the point light source 30 to the back surface 54 side, and there may be light transmitted from the recess 53 to the diffusion plate 60.

As described above, the recess 53 reflects the light emitted from the point light source 30 toward the back surface 54 side. The light intensity of the incident light is strong directly above the point light source 30 of the exit surface 51, but by reflecting most of the light emitted from the point light source 30 by the recess 53 toward the back surface 54, the light intensity directly above the point light source 30 Can be reduced. In other words, by reflecting the light from the point light source 30 by the concave portion 53, it is possible to suppress the increase in the luminance of the region of the emission surface 51 corresponding to the portion directly above the point light source 30.

As described above, the light distribution of the light emitted from the point light source 30 is controlled so that the light intensity becomes uniform on the light emission surface 51. In other words, the lens 50D can equalize the luminance by dispersing the light incident immediately above the light source with high light intensity over the entire emission surface 51.

The flat portion 57 is a flat surface provided continuously with the concave portion 53, and emits the light reflected again by the reflection portion 56 to the diffusion plate 60.

The reflective portion 56 is a dot that protrudes from the back surface 54 in the thickness direction of the lens 50D, and is uniformly formed on the entire back surface 54, for example. The reflection unit 56 reflects the light reflected to the back surface 54 side at the emission surface 51 again to the emission surface 51 side. In addition, the shape of the reflection part 56 is not limited to a dot.

The light emitted from the point light source 30 is reflected toward the back surface 54 by the recess 53 as described above. Subsequently, the light is reflected again to the emission surface 51 side by the reflection portion 56 provided on the back surface 54. Then, the light reflected by the reflection portion 56 is emitted from the flat portion 57 of the emission surface 51. That is, the light emitted from the point light source 30 is guided in the lens 50D, converted to substantially surface light emission, and emitted.

As described above, in the lens 50D according to the fourth embodiment, the light distribution is controlled so that the light incident from the point light source 30 is uniformly emitted from the entire emission surface 51. That is, according to the lens 50D according to the present embodiment, it is possible to improve the uniformity of the luminance.

Next, the shape of the back surface 54 of the lens 50D according to the embodiment will be described with reference to FIG. FIG. 14 is a perspective view of a lens 50D according to the fourth embodiment as viewed from the back surface 54 side. In FIG. 14, the description of the reflecting portion 56 and the like shown in FIG. 13 is omitted.

As shown in FIG. 14, the lens 50 D according to the fourth embodiment has a ridge 58 projecting like a ridge. The ridge portion 58 is substantially orthogonal to the row of point light sources 30 in which the two opposing sides of the bottom face are covered by the lens 50D, and the two opposing sides of the bottom are substantially parallel to the row of the point light sources 30 covered by the lens 50D.

That is, the ridge portion 58 can suppress transmission of light from the back surface 54 to the point light source 30 side, and can suppress light leakage to the adjacent lens 50D. In addition, the tip of the collar portion 58 is formed in a plane along the bottom surface of the collar portion 58, but is not limited thereto. That is, the tip of the collar portion 58 may have a convex shape or a concave shape. Moreover, in the example shown in FIG. 14, the collar part 58 is pyramid-shaped. More specifically, the collar portion 58 is constituted by an inclined portion 59a inclined along the longitudinal direction (X axis) of the lens 50D and an inclined portion 59b inclined along the lateral direction (Y axis) of the lens 50D. Be done. In addition, the collar part 58 is not limited to pyramid shape, You may decide to form a side surface by one of the inclination part 59a and the inclination part 59b.

Moreover, although description is abbreviate | omitted here, the collar part 58 forms the reflection part 56 mentioned above. Further, the valley of the adjacent ridge portion 58 corresponds to the above-described boundary area, and the transmission portion 52 is formed on the side of the light-exit surface 51 of the boundary area. That is, the transmissive portion 52 is formed in the region corresponding to the valley of the adjacent ridge portion 58.

Next, light distribution characteristics of the lens 50D according to the fourth embodiment will be described using FIG. FIG. 15 is a view showing the light distribution characteristic of the lens 50D according to the fourth embodiment. In FIG. 15, the optical path of light is indicated by a broken line.

As shown in FIG. 15, the light emitted from the point light source 30 is reflected by the concave portion 53 to the back surface 54 side as described above. Subsequently, the light is reflected to the emission surface 51 side again by a reflection portion 56 provided on the back surface 54 described later. Then, the light reflected by the reflection portion 56 is emitted from the flat portion 57 of the emission surface 51 to the diffusion plate 60. Furthermore, a part of the outgoing light is refracted and transmitted by the transmission part 52, and the outgoing light is promoted to the boundary part with the adjacent outgoing surface 51.

The light reflected to the back surface 54 side by the concave portion 53 is reflected to the emission surface 51 side by the reflecting portion 56, but a part of the light passes through the reflecting portion 56. At this time, such light enters the inclined portion 59 at a predetermined incident angle. Thereby, the light reflected to the back surface 54 side by the output surface 51 is reflected again to the output surface 51 side by the inclined portion 59.

That is, the lens 50D promotes the total reflection by the collar portion 58 by providing the collar portion 58 on the back surface 54, and reflects the light to the emission surface 51 side. That is, the collar portion 58 suppresses transmission of light from the back surface 54 to the point light source 30 side. Moreover, the collar part 58 can suppress the light leakage to the adjacent output surface 51 side.

In addition, a reflective portion 56 is formed on the back surface 54. The reflecting portion 56 has a function of reflecting the light reflected from the emission surface 51 to the back surface 54 side to the emission surface 51 as in the case of the inclined portion 59. As described above, the lens 50D according to the embodiment can suppress transmission of light from the back surface 54 by having the ridge portion 58 and the reflection portion 56 on the back surface 54. In addition, the lens 50D can suppress the light guiding of the light to the side of the adjacent emission surface 51 by having the ridge portion 58 and the reflection portion 56 on the back surface 54. In other words, the emission efficiency and the brightness uniformity can be improved by suppressing the leakage of the light to the adjacent emission surface 51 side (adjacent point light source 30 side). Moreover, it is also possible to improve the contrast when the point light sources 30 are individually turned on.

Therefore, according to the lens 50D, it is possible to improve the contrast and the uniformity of the luminance when the point light sources 30 are individually lit.

Next, a simulation result showing the luminance distribution of the lens 50D will be described with reference to FIGS. 16 and 17 are diagrams showing simulation results of the lens 50D according to the fourth embodiment. Note that in FIG. 16, the luminance is represented by shading, and the lighter the shading, the stronger (brighter) the luminance is. Further, FIG. 17 shows that the darker the shade, the stronger the luminance.

First, the simulation result of the luminance distribution when the point light source 30 is lit with 96 lamps (six lamps in the short direction and 16 lamps in the longitudinal direction) will be described with reference to FIG. In addition, below, the simulation result of the lens without the collar part 58 and the permeation | transmission part 52 is shown for a comparison. Further, a region surrounded by a square in FIG. 16 corresponds to the above-described boundary region.

As shown in FIG. 16, when the boundary area is compared between the lens without the ridge portion 58 and the transmission portion 52 and the lens 50 D, it can be seen that the brightness of the boundary area is improved in the lens 50 D.

In addition, as shown in FIG. 17, when one point light source 30 is turned on, comparing the area surrounded by a square, the point light source 30 of the lens 50 D is better than the lens without the ridge 58 and the transmission 52. It can be seen that the light is narrowly guided.

That is, in the lens 50D, the light is prevented from being guided from the back surface 54 to the adjacent point light source 30 side and the adjacent lens 50D side by the flange portion 58 and the transmission portion 52, so that the contrast is improved. It is also supported by

As described above, the lens 50D is a lens that covers the plurality of point light sources 30 arranged in a row from the emission direction, and the main surface which is the emission surface 51, the back surface 54 facing the main surface, and the point light source A plurality of recesses 53 recessed in the thickness direction from the main surface toward the back surface 54 at a position corresponding to 30 and a reflecting portion 56 for reflecting light reflected from the main surface toward the back surface 54 toward the main surface are provided. Therefore, according to the lens 50D, the uniformity of the emission efficiency and the brightness can be improved.

By the way, although the case where the collar part 58 is substantially pyramid shape was demonstrated in embodiment mentioned above, it is not limited to this. Subsequently, lenses 50D-1 and 50D-2 according to the modification will be described with reference to FIGS. 18 and 19. FIG.

FIG. 18 and FIG. 19 show a modified example of the collar 58. As shown in FIG. First, a lens 50D-1 according to a first modification will be described with reference to FIG. As shown in FIG. 18, in the lens 50B according to the first modification, the flange 58D-1 is constituted by an inclined portion 59D-1 inclined along the lateral direction (Y-axis direction) of the lens 50D-1. Ru. Further, although the example shown in FIG. 18 shows the case where the tip of the ridge 58D-1 is a flat surface along the bottom of the ridge 58D-1, it is not limited to this.

The inclined portion 59D-1 has a function of suppressing the emission of light in the short direction from the back surface 54D-1 of the lens 50D-1, and reflecting the light to the emission surface side of the lens 50D-1. In addition, as shown in FIG. 19, in the lens 50D-2 according to the second modification, the ridge portion 58D-2 is an inclined portion 59D- inclined along the longitudinal direction (X-axis direction) of the lens 50D-2. It consists of two. Further, although the example shown in FIG. 19 shows the case where the tip of the ridge 58D-2 is a flat surface along the bottom of the ridge 58D-2, it is not limited to this. The inclined portion 59D-2 has a function of suppressing the emission of light from the back surface 54D-2 corresponding to the above-described emission region and reflecting the light to the emission surface side of the lens 50D-2.

Even when any of the lens 50D-1 according to the first modification and the lens 50D-2 according to the second modification is used, it can be expected to improve the uniformity of the emission efficiency and the luminance. Further, in the above-mentioned

flanges

58, 58D-1 and 58D-2, although the case where the

slopes

59, 59D-1 and 59D-2 are formed to be flat is described, the present invention is not limited thereto. , And at least a part of the curved surface. Also, the collar 58 may have five or more slopes 59. That is, the bottom surface of the collar portion 58 may be pentagonal or more.

Fifth Embodiment
Subsequently, a lighting apparatus according to a fifth embodiment will be described with reference to FIGS. 20 to 26. In the fifth embodiment, the reflection plate 40 will be mainly described. FIG. 20 is a top view of the reflecting plate 40. FIG. In FIG. 20, a part of the reflecting plate 40 is extracted and shown, and the point light source 30 and the lens 50 are shown together. As shown in FIG. 20, the reflecting plate 40 includes a bottom surface 41 and a frame portion 42.

The bottom surface 41 is provided with a plurality of openings, and the point light source 30 mounted on the substrate 20 is inserted from the substrate 20 side through the openings. The frame 42 encloses the side of each point light source 30. Since the point light sources 30 are arranged in a lattice, the frame portions 42 are formed in a lattice so as to surround the side surfaces of the point light sources 30 arranged in a lattice.

Thus, the reflecting plate 40 which concerns on embodiment is provided so that each point light source 30 may be divided. Thereby, it is possible to suppress that the light reflected to the reflection plate 40 by the lens 50 leaks to the adjacent point light source 30 and that the light is directly incident on the reflection plate 40 from the point light source 30. In other words, it is also possible to improve the contrast when the point light sources 30 are individually lit. For example, the frame portion 42 has a tapered shape that protrudes from the bottom surface 41 toward the lens 50 and narrows in width from the bottom surface 41 toward the lens 50.

Then, the cross-sectional shape of the reflecting plate 40 which concerns on embodiment using FIG. 21 is demonstrated. FIG. 21 is a schematic cross-sectional view taken along the line DD shown in FIG. In FIG. 21, the lens 50 and the point light source 30 are shown together.

As shown in FIG. 21, in a cross-sectional view, the frame portion 42 has a tapered shape that extends from the lens 50 side toward the substrate 20 (point light source 30). In other words, when viewed from each of the point light sources 30, the frame portion 42 is inclined upward.

Further, the lens 50 has a recess 53 recessed in the thickness direction immediately above the point light source 30 on the exit surface 51. In the present embodiment, the cross-sectional shape of the concave portion 53 is formed in a substantially inverted conical shape (or a weir shape). The concave portion 53 has a function of reflecting the light emitted from the point light source 30 to the back surface 54 side. In the recess 53, it is not necessary to reflect all the light emitted from the point light source 30 to the back surface 54 side, and there may be light transmitted from the recess 53 to the diffusion plate 60.

In addition, on the back surface 54 of the lens 50, a reflective portion 56 is formed. The reflective portion 56 is, for example, a dot protruding from the back surface 54 in the thickness direction, and is uniformly formed on the entire back surface 54, for example. The optical characteristics of the concave portion 53 and the reflecting portion 56 will be described later together with the optical characteristics of the reflecting plate 40 with reference to FIG. Also, the reflective portion 56 is not limited to dots.

Further, as shown in FIG. 21, the rear surface 54 of the lens 50 is disposed on the upper surface of the frame portion 42. That is, the height of the leg 55 is formed higher than that of the frame 42 with reference to the bottom surface 41. The lens 50 may be provided so as to face at least a part of the point light source 30 with the opening surface 45 of the frame 42 interposed therebetween. In other words, the planar illumination device 1 can exhibit the effects described later if the emission surface 51 of the lens 50 is disposed on the upper surface of the frame 42.

The opening surface 45 is a surface connecting the tip portions of the frame portion 42 corresponding to one point light source 30, and the opening surface 45 is indicated by a broken line in FIG. The opening surface 45 does not necessarily have to be a flat surface, and may include a curved surface. In addition, the lens 50 may be made larger than the opening surface 45 of the frame 42 in top view, and the lens 50 may be installed on the frame 42. Further, the frame portion 42 is not limited to the tapered shape, and may have a rectangular shape in a cross sectional view.

Next, the shape on the back surface 54 side of the lens 50 according to the embodiment will be described with reference to FIG. FIG. 22 is a perspective view seen from the back surface 54 side of the lens 50 according to the embodiment. In addition, in FIG. 22, description of the reflection part 56 shown in FIG. 21 is abbreviate | omitted and shown.

As shown in FIG. 22, for example, four legs 55 are formed on the back surface 54 of the lens 50. The four legs 55 are formed, for example, at the same height. Further, adhesive members such as an adhesive and a tape are respectively applied to the bottom surfaces of the legs 55 and fixed to the substrate 20.

Thus, the lens 50 can be firmly fixed to the substrate 20. In other words, positional deviation between the lens 50 and the point light source 30 can be prevented. Here, although the case where the lens 50 includes the four legs 55 is shown, the number of the legs 55 may be three or less, or five or more. Also, the lens 50 may be fixed other than the leg 55.

Next, light distribution characteristics of the reflecting plate 40 and the lens 50 according to the fifth embodiment will be described with reference to FIG. FIG. 23 is a view showing light distribution characteristics of the lens 50 and the reflection plate 40 according to the fifth embodiment. In FIG. 23, the optical path of light is indicated by a broken line.

The light emitted from the point light source 30 is reflected by the concave portion 53 to the back surface 54 side. Subsequently, the light is reflected again to the emission surface 51 side by the reflection portion 56 provided on the back surface 54. Then, the light reflected by the reflection unit 56 is emitted from the flat portion 57 of the emission surface 51.

Although the light reflected to the back surface 54 side by the concave portion 53 is reflected again to the emission surface 51 side by the reflecting portion 56 provided on the back surface 54, a part of the light passes through the back surface 54 as illustrated. The light transmitted through the back surface 54 is guided to the reflection plate 40.

At this time, when light enters the frame portion 42, the light is reflected by the inclined surface of the frame portion 42 and is emitted from between the lenses 50. That is, by providing the frame portion 42 in an inclined manner, light passing through the back surface 54 can be emitted from between adjacent lenses 50.

Thus, light can be emitted not only from the lens 50 but also from the periphery of the lens 50. That is, the planar illumination device 1 according to the embodiment can emit surface light over the entire opening when one opening of the frame 42 is regarded as one output surface.

This makes it possible to improve the brightness of the boundary area between adjacent lenses 50, that is, the uniformity of the brightness. Further, by providing the frame portion 42, it is possible to suppress the leakage of light to the opening of the adjacent frame portion 42. This makes it possible to improve the brightness contrast between the adjacent lenses 50.

Therefore, according to the planar illumination device 1 which concerns on embodiment, it becomes possible to improve both the uniformity and the contrast of a brightness | luminance. In addition, since the light leakage to the adjacent lens 50 side is suppressed by the frame portion 42, improvement of the emission efficiency can also be expected.

Next, the comparison result according to the presence or absence of the frame portion 42 will be described with reference to FIGS. 24 to 26. FIGS. 24 to 26 are diagrams showing comparison results of luminance distribution according to the presence or absence of the frame portion 42 according to the fifth embodiment. FIGS. 24 to 26 show simulation results of luminance distribution when nine point light sources 30 are arranged in a grid shape and the different number of point light sources 30 are lighted. Moreover, the circles shown in the following drawings indicate the positions of the point light sources 30, respectively. In the following, in FIG. 24 and FIG. 25, the luminance is represented by light and shade, the higher the light and dark, the higher the luminance, and the lower light and dark in FIG.

First, the comparison result when 9 lamps are lit will be described using FIG. As shown in FIG. 24, it can be seen that the luminance is generally improved in the case where the frame portion 42 is present in the reflection plate 40 as compared with the case where the frame portion 42 is not provided in the reflection plate 40.

This is because, as described above, the frame portion 42 improves the emission efficiency. That is, since the light emitted from the point light source 30 can be efficiently emitted from the side of the emission surface 51 without leaking to the adjacent point light source 30 side by the frame portion 42, the brightness contrast can be improved. Become.

Next, the case where the five point light sources 30 located at the four corners and the center are turned on will be described with reference to FIG. As shown in FIG. 25, the luminance on the lit point light source 30 is improved when the frame 42 is present compared to when the frame 42 is not present, and the boundary between the non-lit point light sources 30 Is clear.

That is, when there is no frame portion 42, the brightness on the lit point light source 30 is weak, and the boundary between adjacent point light sources 30 is unclear as compared with the case where the frame portion 42 is present. On the other hand, when the frame portion 42 is present, the emission efficiency is high as compared with the case where the frame portion 42 is not present, so the luminance on the lit point light source 30 becomes strong. Further, since light is not leaked to the adjacent point light source 30 side by the frame portion 42, it is possible to improve the contrast with the point light source 30 which is not lit.

Next, the case where one point light source 30 located at the center is turned on will be described with reference to FIG. As shown in FIG. 26, with the frame portion 42, the luminance at the center directly above the point light source 30 is improved, and the contrast with the other point light sources 30 is improved.

That is, in any of the cases shown in FIG. 24 to FIG. 26, the luminance and the contrast are improved in the case where the frame portion 42 is provided in the reflection plate 40 as compared with the case where the frame portion 42 is not provided in the reflection plate .

That is, the planar illumination device 1 according to the embodiment can improve the contrast and the uniformity of the luminance even in various lighting patterns by providing the frame portion 42 in the reflection plate 40.

Sixth Embodiment
The sixth embodiment will be described next. In the sixth embodiment, a fixing mode of the lens 50B shown in FIG. 8 will be described. First, the shape on the back surface side of the lens 50B will be described with reference to FIG. FIG. 27 is a perspective view of the back surface 54 side of the lens 50 according to the embodiment. As shown in FIG. 27, the lens 50 according to the embodiment includes, for example, two

first legs

55 a and 55 b and a second leg 55 c shorter than the

first legs

55 a and 55 b.

The

first legs

55 a and 55 b and the second legs 55 c protrude from the back surface 54 toward the substrate 20. The

first legs

55a and 55b are for positioning the lens 50 on the substrate 20, and the second legs 55c are for maintaining a constant distance from the lens 50 to the substrate 20. is there. Details of this point will be described later with reference to FIG. The first leg 55a may have a stepped shape as shown in FIG. 27, but is not limited to this.

Subsequently, the bottom surface 21 of the substrate 20 according to the embodiment will be described with reference to FIG. FIG. 28 is a bottom view of the substrate 20 according to the embodiment. As shown in FIG. 28, the substrate 20 has a plurality of holes 22 in the bottom surface 21.

The plurality of holes 22 are through holes that respectively penetrate the substrate 20, and have a plurality of holes 22 for one lens 50. The example shown in FIG. 28 shows the case where one lens 50 has the first hole 22 a and the second hole 22 b.

The first hole 22 a is provided substantially at the center of the lens 50 in the longitudinal direction (X-axis direction). The first leg 55a provided substantially at the center of the lens 50 in the longitudinal direction is inserted into the first hole 22a. The second hole 22 b is provided on one end side in the longitudinal direction of the lens 50. The first leg 55b provided at one end of the lens 50 in the longitudinal direction is inserted into the second hole 22b.

As shown in FIG. 28, the first hole portion 22 a has a substantially circular shape, whereas the second hole portion 22 b has an elliptical shape cut away in the longitudinal direction of the lens 50. Details of this point will be described later using FIG.

Since the plurality of holes 22 are through holes, the plurality of holes 22 are also formed on the mounting surface which is the main surface on which the point light source 30 is mounted. The plurality of holes 22 need not be through holes, and may be recessed in the thickness direction from the mounting surface. That is, the plurality of holes 22 may be formed in the mounting surface at a depth at which the

first legs

55a and 55b can be fixed.

Subsequently, a fixing aspect of the lens 50 and the substrate 20 according to the embodiment will be described with reference to FIGS. 29 to 31 are schematic views showing how the lens 50 and the substrate 20 are fixed according to the embodiment.

First, a fixing aspect of the lens 50 and the substrate 20 as viewed from the short side direction (the Y-axis positive direction) of the lens 50 will be described with reference to FIG. As shown in FIG. 29, the lens 50 is positioned on the substrate 20 by inserting the first leg 55 a of the lens 50 into the first hole 22 a.

Also, the first hole 22a is formed to fit with the first leg 55a. Further, as shown in FIG. 29, the second leg 55 c abuts on the substrate 20. That is, while the first leg 55 a is for positioning on the substrate 20, the second leg 55 c is for holding the distance between the substrate 20 and the lens 50 constant.

Thus, the lens 50B is positioned on the substrate 20 by the first leg 55a, and the distance between the lens 50B and the substrate 20 is held constant by the second leg 55c.

Also, although not shown here, the lens 50 can also be inserted by inserting the first leg 55b (see FIG. 4) into the second hole 22b (see FIG. 5) in addition to the first leg 55a. It is fixed on the substrate 20. That is, the lens 50 is positioned on the substrate 20 at at least two points.

Thereby, it is possible to prevent the lens 50 from being displaced from the substrate 20 with respect to the vibration from the side (the XY plane direction) with respect to the lens 50. If the lens 50 is positioned on the substrate 20 at one point, the lens 50 may rotate on the substrate 20 about the one point. For this reason, the lens 50 is fixed on the substrate 20 by at least two

first legs

55 a and 55 b. Thereby, positional deviation between the lens 50 and the point light source 30 mounted on the substrate 20 can be suppressed.

Next, a fixing aspect of the lens 50 and the substrate 20 as viewed from the longitudinal direction (X-axis direction) of the lens 50 will be described with reference to FIG. In FIG. 30, the second leg 55c is omitted to simplify the description.

As shown in FIG. 30 and as described above, the first leg 55a is inserted into the first hole 22a, and the first leg 55b is inserted into the second hole 22b. Here, while the first hole 22a is fitted to the first leg 55a, the second hole 22b is formed wider than the outer periphery of the first leg 55b. That is, the first leg 55b is inserted into the second hole 22b while being separated.

This is because the lens 50 thermally expands as described above. If the second hole 22b is formed to be fitted to the first leg 55b, the lens 50 is thermally expanded and concentrated on two points of the first leg 55a and the first leg 55b. Works. As a result, the lens 50 may be damaged or the shape of the lens 50 may be changed.

On the other hand, by forming the second hole 22b wider than the outer periphery of the first leg 55b, the first leg 55b moves inside the second hole 22b when the lens 50 is thermally expanded. You just have to do it. That is, it is possible to avoid that the above-described force acts on two points of the first leg 55a and the first leg 55b.

By forming the second hole 22b wider than the outer periphery of the first leg 55b in this manner, damage or deformation of the lens 50 due to thermal expansion can be avoided. In other words, the product life of the lens 50 can be extended. Here, although the thermal expansion of the lens 50 has been described as an example, the same applies to the thermal contraction that occurs when the ambient temperature decreases.

Further, as shown in FIG. 31, the lens 50B is supported by the frame portion 42 from the bottom surface side. That is, the frame portion 42 can support not only the above-described light distribution control but also the lens 50B.

Further, the lens 50B is pressed by the spacer 70 from the upper surface side. A predetermined pressing force is applied to the spacer 70 from the upper frame 11 (see FIG. 3A and the like), and the spacer 70 can press the lens 50B by the pressing force.

That is, the lens 50B is fixed on the substrate 20 by inserting the leg 55 (

first leg

55a, 55b) into the through hole provided in the substrate 20. Thereby, the lens 50B can be prevented from being displaced from the substrate 20 in the side surface (XY plane) direction. That is, the lens 50B is pressed by the spacer 70 from the upper surface, and is positioned on the substrate 20 by the leg 55B. Thereby, since the positional deviation of the lens 50B can be suppressed, it is possible to suppress the deterioration of the light distribution characteristic due to the positional deviation of the lens 50B.

As described above, the substrate 20 has the main surface on which the plurality of point light sources 30 are mounted in a lattice. The plurality of lenses 50 individually covers the plurality of point light sources 30 aligned in the arrangement direction in the short direction, and is provided in parallel along the longitudinal direction. The frame 10 accommodates the substrate 20 and the plurality of lenses 50. The elastic member 90 is provided between the top plate 11a of the frame 10 and the lens 50, and presses the lens 50 from the top plate side. Therefore, positional deviation of the lens 50 can be suppressed.

<Others>
Next, the

planar illumination devices

1E and 1F according to the modification will be described with reference to FIGS. 32 and 33. FIG. 32 is a schematic cross-sectional view of a planar illumination device 1E according to a first modification, and corresponds to a schematic cross-sectional view along the line AA shown in FIG.

As shown in FIG. 32, the planar illumination device 1E according to the first modification is different from the above-described planar illumination device 1 in that the arrangement of the elastic member 90 and the spacer 70 is different. Specifically, in the planar illumination device 1E according to the first modification, the elastic member 90 doubles as a part of the spacer 70.

In the example shown in FIG. 32, the elastic member 90 is disposed between the lens 50 and the diffusion plate 60. The lens 50 and the diffusion plate 60 need to be disposed at a predetermined interval, and the spacer 70 plays a role of keeping the interval constant.

On the other hand, the planar illumination device 1E according to the first modification substitutes a part of the spacer 70 by the elastic member 90. Thereby, in the planar illumination device 1B according to the first modification, the elastic member 90 plays the role of pressing the lens 50 from the top plate 11a side of the upper frame 11, and fills the space between the lens 50 and the diffusion plate 60. Take on the role at once.

Therefore, as shown in FIG. 3A and FIG. 3B, the spacer 70 between the diffusion plate 60 and the top plate 11a becomes unnecessary. That is, when the elastic member 90 doubles as a part of the spacer 70, it becomes possible to reduce the thickness by the amount of the elastic member 90 disposed on the diffusion plate 60.

Although the elastic member 90 is disposed between the diffusion plate 60 and the spacer 70 here, the elastic member 90 may be disposed between the lens 50 and the spacer 70. . Alternatively, the spacer 70 may be entirely composed of the elastic member 90.

That is, the elastic member 90 may double as part or all of the spacer 70. Although the case where the elastic member 90 defines the distance between the lens 50 and the diffusion plate 60 as an optical member has been described here, the present invention is not limited to the diffusion plate 60, and the elastic member 90 includes the lens 50 and other optical elements. The distance to the member may be defined.

Further, as shown in FIG. 32, in the first modified example, the spacer 70 is disposed to abut on the bottom 12 a of the lower frame 12. In other words, the spacer 70 is pressed from the top by the top plate 11 a of the upper frame 11 through the optical sheet 80, the diffusion plate 60 and the elastic member 90, and the bottom is supported by the bottom 12 a of the lower frame 12.

That is, in the first modified example, the spacer 70 is provided so as to be pressed in the vertical direction (Z-axis direction). As a result, since the positional deviation of the spacer 70 can be suppressed, the positional deviation of the lens 50 due to the positional deviation of the spacer 70 can be suppressed. The bottom surface of the spacer 70 may not be supported by the bottom 12 a of the lower frame 12.

Subsequently, a planar illumination device 1F according to a second modification will be described with reference to FIG. FIG. 33 is a schematic cross-sectional view of a planar illumination device 1F according to a second modification, and corresponds to a schematic cross-sectional view along the line AA shown in FIG.

As shown in FIG. 33, the planar illumination device 1F according to the second modification is different in that the shapes of the planar illumination device 1 and the reflection plate 40 described above are different. Specifically, in the planar illumination device 1C according to the second modified example, the reflection plate 40 is integrally formed with the above-described spacer 70 (see FIG. 3A, FIG. 3B, etc.).

More specifically, the reflecting plate 40 is fixed on the substrate 20 and extends from the bottom to the top plate side of the upper frame 11 along the side wall 12 b of the lower frame 12, and is fixed between the lens 50 and the diffusion plate 60. A projecting portion 43 that protrudes to the inside of the planar lighting device 1F with a thickness of

That is, in the planar illumination device 1F according to the second modification, the protrusion 43 corresponds to the spacer 70. Further, the projecting portion 43 is pressed by the diffusion plate 60 from the upper surface, and the lower surface is supported by the substrate 20.

That is, in the planar illumination device 1F according to the second modification, by integrally molding the reflecting plate 40 and the spacer 70, the projecting portion 43 corresponding to the spacer 70 can be fixed so as to be sandwiched from above and below. it can. Therefore, in the planar illumination device 1F according to the second modification, since the positional deviation of the protrusion 43 is not easily generated, the lens 50 can be firmly fixed.

In the examples shown in FIGS. 32 and 33, although the case where the elastic member 90 and the reflection plate 40 also function as at least a part of the spacer 70 has been described, the present invention is not limited to this. The diffusion plate 60 may also function as at least a part of the spacer 70. In such a case, it can be realized by providing the diffusion plate 60 with a protruding portion that protrudes from the diffusion plate 60 toward the lens 50. As a result, the number of parts can be reduced by the amount of the spacer 70, so that the assembly of the planar illumination device 1 can be simplified.

Further, the present invention is not limited by the above embodiment. What is configured by appropriately combining the above-described constituents is also included in the present invention. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above embodiment, and various modifications are possible.

Claims

A lens for covering point light sources arranged in a row from the emission direction,
A main surface which is an exit surface;
A back surface opposite to the main surface;
A plurality of recesses recessed in the thickness direction from the main surface toward the back surface at positions corresponding to the point light sources;
A lens configured to reflect light reflected from the main surface toward the back surface toward the main surface.
A lens according to claim 1;
A substrate for mounting a plurality of the point light sources arranged in a grid pattern;
A planar illumination device comprising: a frame accommodating a plurality of the lenses and the substrate.
The lens is
The planar illumination device according to claim 2, wherein a plurality of the point light sources arranged in the arrangement direction in the short direction are singly covered and provided in parallel along the longitudinal direction.
The lens is
The planar illumination device according to claim 3, further comprising: a hook portion provided on the back surface and protruding like a hook from the position corresponding to the point light source toward the point light source.
The buttocks are
The planar illumination device according to claim 4, wherein two opposing sides of the bottom surface are substantially orthogonal to the row of point light sources.
The buttocks are
The planar illumination device according to claim 4 or 5, wherein two opposing sides of the bottom surface are substantially parallel to the row of point light sources.
The substrate is
The main surface has a plurality of holes,
The lens is
It has a first leg projecting from the main surface facing the substrate toward the substrate and having a first leg inserted into the hole, and a second leg shorter than the first leg and abutting on the substrate. The planar lighting device as described in any one of 6.
The lens is
Having a plurality of said first legs,
The substrate is
The plurality of holes corresponding to the plurality of first legs are provided, and the corresponding first legs are fitted and inserted in at least one of the plurality of holes. The planar illumination device according to claim 7, wherein at least one corresponding first leg is inserted at a distance.
And a diffuser for diffusing the light emitted from the lens.
The lens is
The planar illumination device according to any one of claims 2 to 8, which is pressed from the top plate side of the frame via a spacer that defines the distance between the lens and the diffusion plate.
The planar illumination device according to any one of claims 2 to 9, further comprising: an elastic member provided between a top plate of the frame and the lens and pressing the lens from the top plate side.
The optical sheet further includes an optical sheet disposed on the diffusion plate and smaller than the diffusion plate in top view.
The elastic member is
The planar illumination device according to claim 10, wherein the planar illumination device is disposed between the diffusion plate and the top plate, and is disposed to avoid the main surface of the optical sheet.
The elastic member is
The planar illumination device according to claim 11, wherein the diffusion plate is pressed via the optical sheet.
The elastic member is
The planar illumination device according to claim 10, wherein the planar illumination device doubles as part or all of the spacer.
The elastic member is
The planar illumination device according to claim 13 disposed between the lens and the spacer.
A reflecting plate having a frame portion surrounding side surfaces of the plurality of point light sources;
The lens is
The planar illumination device according to any one of claims 2 to 14, which is supported by the frame portion.
A reflecting portion provided on a back surface that is a main surface facing a point light source, and reflecting light reflected to the back surface side from an emitting surface that is a main surface facing the back surface,
A recessed portion recessed in the thickness direction from the light emission surface at a portion immediately above the point light source;
A transmitting portion provided at an outer peripheral portion of the recess and transmitting light from the emission surface.
The lens is
Provided for each point light source,
The transparent portion is
The lens according to claim 16, wherein the lens abuts on each side of the exit surface.
The transparent portion is
The lens according to claim 16 formed concentrically.
The lens is
The lens according to claim 16, further comprising: a ridge portion provided on the back surface and protruding like a ridge toward the point light source from a position corresponding to the point light source.
The lens is
Of the point light sources arranged in a grid, a plurality of point light sources are covered alone;
The transparent portion is
The lens according to claim 16, provided in a boundary area of the point light sources adjacent to each other.
21. A lens according to any one of claims 16 to 20, and a substrate on which a plurality of the point light sources arranged in a grid are mounted;
A planar illumination device comprising: a frame accommodating a plurality of the lenses and the substrate.
And a reflector having a frame surrounding the side of each of the plurality of point light sources.
The lens is
The planar illumination device according to claim 21, wherein at least a part is provided to face the point light source across the opening surface of the frame portion.