Backlight and display device

Abstract

To enable irradiation of parallel light.SOLUTION: A backlight 10 includes: a plurality of light sources 12 flatly arranged and each enabling emission of divergent light; a plurality of first lenses 14 flatly arranged, overlapping with each other above the plurality of light sources 12 and having a shape of reducing a divergence angle of the divergent light; a plurality of second lenses 18 flatly arranged, overlapping with each other above the plurality of first lenses 14 and having a shape of further reducing the divergence angle; and partition walls 24 located between the plurality of first lenses 14 and the plurality of second lenses 18, surrounding each of the plurality of first lenses 14 and shielding part of the divergent light to reduce an irradiation region 28B of the divergent light toward each of the plurality of second lenses 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a backlight and a display device. [Background technology]

[0002] To obtain a surface light source, a backlight in which multiple point light sources are arranged in a plane is used (Patent Documents 1 and 2). Ideally, parallel light should be emitted from the backlight, but since light from point light sources has a diffusive nature, multiple lenses are required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 029600 [Patent Document 2] Japanese Patent Application Publication No. 2018-56367 Summary of the Invention [Problem to be solved by the invention]

[0004] If the illumination range of each point light source is circular, adjacent illumination ranges will partially overlap, resulting in light entering adjacent lenses and making it difficult to obtain parallel light. Note that Patent Documents 1 and 2 aim to reduce brightness unevenness and do not take into consideration the illumination of parallel light.

[0005] An object of the present invention is to enable irradiation with parallel light. [Means for solving the problem]

[0006] The backlight has a plurality of light sources arranged in a plane and each capable of emitting divergent light, a plurality of first lenses arranged in a plane and overlapping the plurality of light sources above each other to reduce the divergence angle of the divergent light, a plurality of second lenses arranged in a plane and overlapping the plurality of first lenses above each other to further reduce the divergence angle, and partition walls between the plurality of first lenses and the plurality of second lenses, surrounding each of the plurality of first lenses and blocking a portion of the divergent light to reduce an illumination area of ​​the divergent light directed toward each of the plurality of second lenses. The display device has a backlight and a transmissive display panel. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of a portion of a backlight according to the embodiment. [Figure 2] 2 is a cross-sectional view of the backlight of FIG. 1 taken along line II-II. [Figure 3] 3 is a cross-sectional view of the backlight taken along line III-III in FIG. 1. [Figure 4] FIG. 2 is an explanatory diagram of a light irradiation area of ​​a backlight. [Figure 5] 1 is a schematic cross-sectional view of a display device according to an embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a backlight according to a first modification. [Figure 7] FIG. 10 is a cross-sectional view of a backlight according to Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and the present invention should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same functions as those explained in the previous drawings may be assigned the same reference numerals, and duplicate explanations may be omitted.

[0010] Furthermore, in the detailed description of the present invention, when defining the positional relationship between a certain component and another component, "above" and "below" do not only mean being located directly above or directly below a certain component, but also include cases where there are other components interposed between them, unless otherwise specified.

[0011] Fig. 1 is a plan view of a portion of a backlight according to an embodiment, Fig. 2 is a cross-sectional view of the backlight taken along line II-II of Fig. 1, and Fig. 3 is a cross-sectional view of the backlight taken along line III-III of Fig. 1.

[0012] The backlight 10 has light sources 12 (e.g., light-emitting diodes). The light sources 12 are arranged in a plane (e.g., in multiple rows and multiple columns). The multiple light sources 12 face the same direction. The light sources 12 are capable of emitting divergent light. The divergent light is light (e.g., white light) that spreads from an optical axis in a first direction D1 and a second direction D2 that are orthogonal to each other. The light distribution angle is, for example, ±90 degrees. The light sources 12 are point light sources.

[0013] The backlight 10 has a first lens 14. The multiple first lenses 14 are arranged in a plane (for example, multiple rows and multiple columns). Each of the multiple first lenses 14 overlaps the multiple light sources 12 above. The first lens 14 is a spherical lens. The first lens 14 is a convex lens that protrudes on the side opposite the light source 12. The first lens 14 is shaped to reduce the divergence angle of the divergent light emitted from the light source 12. The light distribution angle is, for example, ±15 degrees.

[0014] The first lens 14 has a circular planar shape. There is a space between adjacent first lenses 14. The distance between adjacent first lenses 14 is wider in a direction intersecting both the first direction D1 and the second direction D2 than in either the first direction D1 or the second direction D2. The irradiation area 28A (see FIG. 4) of the light source 12 (divergent light) on the first lens 14 is circular.

[0015] The multiple first lenses 14 are supported by a transparent substrate 16. For example, the front and back surfaces of the transparent substrate 16 are flat, and the multiple first lenses 14 are located on one of the surfaces. The first lenses 14 and the transparent substrate 16 may be formed as separate bodies and bonded together, or may be integrated. Divergent light from the light source 12 enters each of the first lenses 14 through the transparent substrate 16 and exits from the transparent substrate 16 outside each of the first lenses 14.

[0016] The backlight 10 has a second lens 18. The second lenses 18 are arranged in a plane (for example, in multiple rows and multiple columns). Each of the second lenses 18 overlaps one of the first lenses 14 above. The second lens 18 is a spherical lens. The second lens 18 is a convex lens that protrudes on the side opposite the light source 12. The second lens 18 has a shape that further reduces the divergence angle of divergent light. The light emitted from the second lens 18 is approximately parallel light with a light distribution angle of, for example, ±1.5 degrees or less.

[0017] The second lenses 18 are adjacent to each other. As shown in FIG. 1, the second lenses 18 have a rectangular (e.g., square) planar shape. The sides 20 of the rectangle include a pair of first sides 20A facing each other in the first direction D1 and a pair of second sides 20B facing each other in the second direction D2. The second lenses 18 are adjacent to each other along the rectangular sides 20. The second lenses 18 are integrated to form a lens array 22. The lens array 22 includes the second lenses 18 on one surface and is flat on the other surface.

[0018] The backlight 10 has a partition wall 24. The partition wall 24 is located between the plurality of first lenses 14 and the plurality of second lenses 18 (lens array 22). The partition wall 24 is fixed to the transparent substrate 16. There is a space between the partition wall 24 and the lens array 22 (plurality of second lenses 18). Therefore, the shadow of the partition wall 24 does not appear when viewed from the light-emitting surface of the backlight 10, and therefore the backlight 10 is less likely to become dark. Furthermore, since both sides of the transparent substrate 16 are flat, it is easier to attach the partition wall 24 than the lens array 22.

[0019] The partition walls 24 have a lattice-like planar shape. The partition walls 24 surround each of the multiple first lenses 14, and more specifically, have side surfaces 26 surrounding each of the multiple first lenses 14. The side surfaces 26 include a pair of first side surfaces 26A facing the first direction D1 and a pair of second side surfaces 26B facing the second direction D2. The first direction D1 and the second direction D2 are perpendicular to each other. There is a space between each first lens 14 and the side surfaces 26, and part of the surface of the transparent substrate 16 is present therebetween.

[0020] At least the surface (or material) of the partition wall 24 is black. At least the surface (or material) of the partition wall 24 is made of a light-absorbing material. The partition wall 24 blocks a portion of the divergent light, thereby reducing the spread of the divergent light toward each of the multiple second lenses 18. Specifically, the circular spread is transformed into a rectangular spread, and the divergent light is contained within the range of the rectangular planar shape of the second lens 18.

[0021] The following describes how light travels in the backlight 10. The distribution angle of divergent light from the light source 12 is, for example, ±90 degrees. The divergent light enters one surface of the transparent substrate 16, and a portion of it exits through the multiple first lenses 14. The divergence angle of the divergent light is reduced by the first lenses 14, to, for example, ±15 degrees. The other portion of the divergent light exits from the other surface of the optically transparent substrate 16. The front and back surfaces of the transparent substrate 16 are flat and parallel, and the refraction of the incident and exiting light cancels out, so the distribution angle of the light exiting the transparent substrate 16 is ±90 degrees.

[0022] 4 is an explanatory diagram of the light irradiation area of ​​the backlight 10. In the backlight 10, the second lens 18 has a rectangular planar shape (FIG. 1) to obtain a surface light source. On the other hand, the irradiation area 28A (FIG. 4) of the divergent light from the light source 12 is circular. Therefore, the end of the irradiation area 28B (FIG. 4) facing the second lens 18 above the first lens 14 and the transparent substrate 16 faces the adjacent second lens 18 that is adjacent to it at side 20 of the rectangle. If too much light is incident on the adjacent second lens 18, the light will not become parallel light.

[0023] In this embodiment, the partition walls 24 block the ends of the divergent light irradiation area 28B (FIG. 4) and transform the circular irradiation area 28B into a rectangular irradiation area 28C (FIG. 4), preventing the divergent light from entering the adjacent second lens 18. This enables the irradiation of parallel light. The height and thickness of the partition walls 24 are set so as not to block too much of the divergent light. For example, the height and thickness are calculated so as to block a portion of the divergent light (e.g., a light distribution angle of ±18 degrees or more) emitted from the transparent substrate 16 outside each first lens 14, but not to block the divergent light (e.g., a light distribution angle of ±15 degrees) emitted from each first lens 14.

[0024] 5 is a schematic cross-sectional view of a display device according to an embodiment. The display device has a backlight including the second lens 18 described above and a transmissive display panel 30. Light enters the display panel 30 through the second lens 18. The light is white light. In other words, the light incident on the display panel 30 includes red light, green light, and blue light. The light incident on the display panel 30 is also substantially parallel light.

[0025] The display panel 30 has a color separation unit 32. The surface of the substrate of the color separation unit 32 is formed with color separation grooves formed by a predetermined pattern of concaves and convexes. This diffracts and separates white light into its respective R, G, and B wavelength components. The separated light then passes through a color filter 34. In this way, red, green, and blue light are obtained, and by utilizing the optical properties of the liquid crystal, the display panel 30 displays a full-color image.

[0026] [Variation 1] 6 is a cross-sectional view of a backlight according to Modification 1. There is a space between the partition wall 124 and the transparent substrate 116. The partition wall 124 is fixed to the lens array 122 (plurality of second lenses 118).

[0027] [Variation 2] 7 is a cross-sectional view of a backlight according to Modification 2. The partition wall 224 is fixed to the transparent substrate 216 and the lens array 222. There is no space between the partition wall 224 and the transparent substrate 216, and there is also no space between the partition wall 224 and the lens array 222. The partition wall 224 serves as a spacer between the transparent substrate 216 and the lens array 222.

[0028] The present invention is not limited to the above-described embodiments and various modifications are possible. For example, the configurations described in the embodiments can be replaced with substantially the same configurations, configurations that achieve the same effects, or configurations that can achieve the same objectives.

[0029] [Outline of the embodiment] a plurality of second lenses (18) arranged in a plane and overlapping each of the plurality of first lenses (14) above the plurality of first lenses (14) and shaped to further reduce the divergence angle; and a partition wall (24) between the plurality of first lenses (14) and the plurality of second lenses (18) surrounding each of the plurality of first lenses (14) and blocking a portion of the divergent light, thereby reducing an illumination area (28B) of the divergent light directed toward each of the plurality of second lenses (18).

[0030] By blocking a portion of the divergent light and reducing the irradiation area 28B of the divergent light, the divergent light does not enter the adjacent second lens 18, and it becomes possible to irradiate with parallel light. [Explanation of symbols]

[0031] 10 backlight, 12 light source, 14 first lens, 16 transparent substrate, 18 second lens, 20A first side, 20B second side, 22 lens array, 24 partition wall, 26 side, 26A first side, 26B second side, 28A irradiation area, 28B irradiation area, 28C irradiation area, 30 display panel, 32 color separation unit, 34 color filter, 116 transparent substrate, 118 second lens, 122 lens array, 124 partition wall, 216 transparent substrate, 222 lens array, 224 partition wall, D1 first direction, D2 second direction.

Claims

1. a plurality of light sources arranged in a plane and each capable of emitting divergent light; a plurality of first lenses arranged in a plane and overlapping the plurality of light sources above each other, each having a shape that reduces the divergence angle of the divergent light; a plurality of second lenses arranged in a plane and overlapping the plurality of first lenses above each other, and having a shape that further reduces the divergence angle; a partition wall between the plurality of first lenses and the plurality of second lenses, the partition wall surrounding each of the plurality of first lenses and blocking a part of the divergent light to reduce an irradiation area of ​​the divergent light directed toward each of the plurality of second lenses; Having a backlight.

2. 2. The backlight according to claim 1, The plurality of first lenses have spaces between adjacent ones, The plurality of second lenses are adjacent to each other.

3. 3. The backlight according to claim 2, each of the plurality of second lenses has a rectangular planar shape; The backlight, wherein adjacent ones of the plurality of second lenses are adjacent to each other along a side of the rectangle.

4. 4. The backlight according to claim 3, The backlight has a rectangular illumination area for each of the second lenses, the rectangular illumination area being within the range of the rectangular planar shape.

5. 2. The backlight according to claim 1, each of the plurality of first lenses has a circular planar shape; The backlight has a circular illumination area for each of the first lenses.

6. 2. The backlight according to claim 1, The backlight, wherein the plurality of first lenses and the plurality of second lenses are spherical lenses.

7. 2. The backlight according to claim 1, The backlight, wherein the plurality of first lenses and the plurality of second lenses are convex lenses that protrude on a side opposite to the plurality of light sources.

8. 2. The backlight according to claim 1, a transparent substrate supporting the plurality of first lenses; The plurality of second lenses are integrated to form a lens array in the backlight.

9. 9. The backlight according to claim 8, The partition wall is fixed to the transparent substrate.

10. 10. The backlight according to claim 9, A backlight having a space between the partition wall and the lens array.

11. 9. The backlight according to claim 8, The partition wall is fixed to the lens array.

12. 12. The backlight according to claim 11, A backlight having a space between the partition wall and the transparent substrate.

13. 9. The backlight according to claim 8, the partition wall is fixed to the transparent substrate and the lens array; There is no space between the partition wall and the transparent substrate, A backlight in which there is no space between the partition wall and the lens array.

14. 2. The backlight according to claim 1, The partition walls are of a backlight having a lattice-like planar shape.

15. 2. The backlight according to claim 1, the partition wall has side surfaces surrounding each of the plurality of first lenses, The side surfaces include a pair of first side surfaces facing each other in a first direction and a pair of second side surfaces facing each other in a second direction, The first direction and the second direction are orthogonal to each other.

16. 2. The backlight according to claim 1, A backlight in which at least the surface of the partition wall is black.

17. 2. The backlight according to claim 1, At least the surfaces of the partition walls are made of a light-absorbing material.

18. A backlight according to any one of claims 1 to 17; a transmissive display panel; A display device having:

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