Backlight and display device

Abstract

To reduce a light distribution angle without using a spherical lens.SOLUTION: A backlight has: a light source 10 which can emit light spread from an optical axis to a first direction D1 and a second direction D2 intersecting with each other; a first cylindrical lens 12 which is overlapped on the light source 10 in a third direction D3 intersecting with the first direction D1 and the second direction D2, and deflects the light so as to make it approach the optical axis in the first direction D1; a second cylindrical lens 14 which is overlapped on the light source 10 and the first cylindrical lens 12 in the third direction D3, and deflects the light so as to make it further approach the optical axis in the first direction D1; and a reflector 16 which is arranged between the first cylindrical lens 12 and the second cylindrical lens 14 in the third direction D3, and reflects the light so as to make it approach the optical axis in the second direction D2 while avoiding an overlap on the light source 10 in the third direction D3.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Ideally, a backlight used in a non-self-luminous display device would irradiate parallel light, but the light emitted from the light source has a spread (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-162748 Summary of the Invention [Problem to be solved by the invention]

[0004] Although a spherical lens can be used to reduce the spread angle of light, it is not necessary to use a spherical lens if the light is to be focused linearly. Also, a spherical lens requires a complex shape for the injection molding die, which increases the number of processing steps.

[0005] An object of the present invention is to reduce the light distribution angle without using a spherical lens. [Means for solving the problem]

[0006] The backlight has a light source capable of emitting light expanding from an optical axis in a first direction and a second direction that are mutually perpendicular, a first cylindrical lens that overlaps with the light source in a third direction that is perpendicular to the first direction and the second direction and refracts the light so as to approach the optical axis in the first direction, a second cylindrical lens that overlaps with the light source and the first cylindrical lens in the third direction and refracts the light so as to approach even closer to the optical axis in the first direction, and a reflector that is between the first cylindrical lens and the second cylindrical lens in the third direction and avoids overlapping with the light source in the third direction and reflects the light so as to approach the optical axis in the second direction.

[0007] The light distribution angle can be reduced without using a spherical lens. The display device includes a backlight and a transmissive display panel. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view of a portion of a backlight according to the embodiment. [Diagram 2] 2 is a cross-sectional view of the backlight shown in FIG. 1 taken along line II-II. [Diagram 3] 3 is a cross-sectional view of the backlight shown in FIG. 1 taken along line III-III. [Figure 4] 1 is a schematic cross-sectional view of a display device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment 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 interpreted as being limited to the description of the embodiment exemplified below.

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner 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 given the same reference numerals, and duplicate explanations may be omitted.

[0011] 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 a component being located directly above or below another component, but also include a component being located between the other components, unless otherwise specified.

[0012] Fig. 1 is a plan view of a portion of a backlight according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of the backlight taken along line II-II in Fig. 1, Fig. 3 is a cross-sectional view of the backlight taken along line III-III in Fig. 1.

[0013] [light source] The backlight has a light source 10 (e.g., a light emitting diode). The light source 10 can emit light (e.g., white light) that spreads from an optical axis in a first direction D1 and a second direction D2 that are perpendicular to each other. The light distribution angle is, for example, 120 degrees to 130 degrees. A plurality of light sources 10 are arranged in a plurality of rows and a plurality of columns. A group of light sources 10 is lined up in the second direction. The plurality of light sources 10 includes a plurality of groups of light sources 10. Each light source 10 is a point light source.

[0014] [First cylindrical lens] The backlight has a first cylindrical lens 12. The first cylindrical lens 12 overlaps the light source 10 in a third direction D3 perpendicular to the first direction D1 and the second direction D2. A plurality of first cylindrical lenses 12 are arranged parallel to each other in the first direction D1.

[0015] A plurality of first cylindrical lenses 12 overlap the plurality of light sources 10. The surface of the first cylindrical lenses 12 facing the light sources 10 is a flat surface. One group of light sources 10 overlaps a corresponding one of the plurality of first cylindrical lenses 12.

[0016] The first cylindrical lens 12 has a convex curved surface that refracts light. The surface opposite the light source 10 is the convex curved surface. The convex curved surface has a shape in which a straight line extending in the second direction D2 is rotated around an axis in the second direction D2. The first cylindrical lens 12 refracts light in the first direction D1 so as to approach the optical axis. The light distribution angle of the refracted light is within 30 degrees.

[0017] [Second cylindrical lens] The backlight has a second cylindrical lens 14. The second cylindrical lens 14 overlaps the light source 10 and the first cylindrical lens 12 in the third direction D3. The multiple light sources 10 overlap the multiple second cylindrical lenses 14. Each of the multiple second cylindrical lenses 14 overlaps a corresponding one of the multiple first cylindrical lenses 12. One group of light sources 10 overlaps a corresponding one of the multiple second cylindrical lenses 14.

[0018] The second cylindrical lens 14 has a convex curved surface that refracts light. The convex curved surface has a shape in which a straight line extending in the second direction D2 is rotated around an axis in the second direction D2. The second cylindrical lens 14 refracts light so as to approach the optical axis in the first direction D1. The light distribution angle of the refracted light is within 3 degrees.

[0019] [Reflector] The backlight has a reflector 16. The reflector 16 extends in a first direction D1. A plurality of reflectors 16 are arranged parallel to a second direction D2. The reflector 16 overlaps the plurality of first cylindrical lenses 12 and the plurality of second cylindrical lenses 14.

[0020] The reflector 16 is located between the first cylindrical lens 12 and the second cylindrical lens 14 in the third direction D3. The reflector 16 has a concave curved surface 18 facing the convex curved surface of the first cylindrical lens 12. This allows the lower end of the reflector 16 to be close to, and preferably coincident with, the lower end of the convex curved surface of the first cylindrical lens 12.

[0021] The reflectors 16 avoid overlapping with the light sources 10 in the third direction D3. Each of the multiple light sources 10 is located between an adjacent pair of the multiple reflectors 16. A pair of reflectors 16 is located on both sides of the light source 10 in the second direction D2.

[0022] The reflector 16 includes a body 20 and a surface layer 22, and the surface layer 22 has light reflectivity. The concave curved surface 18 does not need to have light reflectivity. The reflector 16 has a light reflecting surface 24. The surface of the surface layer 22 is the reflecting surface 24. The reflecting surface 24 is parallel to the first direction D1 and obliquely intersects with the second direction D2 and the third direction D3. Light from the light source 10 passes through the first cylindrical lens 12 and is reflected by the reflecting surface 24. The reflecting surface 24 reflects the light so as to approach the optical axis in the second direction D2. The light distribution angle of the reflected light is within 30 degrees.

[0023] According to this embodiment, the light distribution angle can be reduced without using a spherical lens. Since the light distribution angle is within 3 degrees in the first direction D1 and within 30 degrees in the second direction D2, the light distribution from each light source 10 becomes an ellipse that is long in the second direction D2. In addition, the light distribution from adjacent light sources 10 in the second direction D2 is continuous in the second direction D2. Therefore, a plurality of linear light distribution regions 26 each extending in the second direction D2 can be obtained.

[0024] [Display device] 4 is a schematic cross-sectional view of a display device according to an embodiment. The display device has the above-mentioned backlight. Note that only the second cylindrical lens 14 is shown in FIG.

[0025] The display device has a transmissive display panel 28. Light enters the display panel 28 through the second cylindrical lens 14. The light distribution angle is small, particularly in the first direction D1. The light is white light. That is, the light entering the display panel 28 includes red light, green light, and blue light.

[0026] The display panel 28 has a color separation unit 30. The substrate surface of the color separation unit 30 has color separation grooves formed by a predetermined pattern of unevenness. This causes the white light to be diffracted in a first direction D1 and separated into each of the RGB wavelength components. The separated light further passes through a color filter 32. In this way, red light, green light, and blue light are obtained, and the display panel 28 displays a full-color image by utilizing the optical properties of the liquid crystal.

[0027] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations described in the embodiments can be replaced with substantially the same configurations, configurations that provide the same effects, or configurations that can achieve the same purpose. [Explanation of symbols]

[0028] 10 light source, 12 first cylindrical lens, 14 second cylindrical lens, 16 reflector, 18 concave curved surface, 20 body, 22 surface layer, 24 reflective surface, 26 light distribution area, 28 display panel, 30 color separation unit, 32 color filter, D1 first direction, D2 second direction, D3 third direction.

Claims

1. a light source capable of emitting light spreading from an optical axis in a first direction and a second direction perpendicular to each other; a first cylindrical lens that overlaps the light source in a third direction perpendicular to the first direction and the second direction and refracts the light so as to approach the optical axis in the first direction; a second cylindrical lens that overlaps the light source and the first cylindrical lens in the third direction and refracts the light so as to be closer to the optical axis in the first direction; a reflector that is located between the first cylindrical lens and the second cylindrical lens in the third direction, and that reflects the light in the second direction so as to approach the optical axis while avoiding overlap with the light source in the third direction; Having a backlight.

2. 2. The backlight according to claim 1, each of the first cylindrical lens and the second cylindrical lens has a convex curved surface that refracts the light; The convex curved surface has a shape obtained by rotating a straight line extending in the second direction around an axis in the second direction.

3. 3. The backlight according to claim 2, The reflector is a backlight having a concave surface facing the convex surface of the first cylindrical lens.

4. 2. The backlight according to claim 1, The reflector has a reflecting surface for reflecting the light, The backlight, wherein the reflective surface is parallel to the first direction and obliquely intersects with the second direction and the third direction.

5. 2. The backlight according to claim 1, The backlight includes a reflector including a body and a surface layer, the surface layer having light reflectivity.

6. 2. The backlight according to claim 1, The first cylindrical lens includes a plurality of first cylindrical lenses, the second cylindrical lens includes a plurality of second cylindrical lenses, A backlight, wherein each of the plurality of first cylindrical lenses overlaps a corresponding one of the plurality of second cylindrical lenses.

7. 7. The backlight according to claim 6, The backlight includes a plurality of light sources overlapping the plurality of first cylindrical lenses and the plurality of second cylindrical lenses.

8. 8. The backlight according to claim 7, the plurality of light sources includes a plurality of groups of light sources; The light sources of each group of backlights overlap a corresponding one of the first plurality of cylindrical lenses and the corresponding one of the second plurality of cylindrical lenses.

9. 7. The backlight according to claim 6, The reflector is a backlight that extends in the first direction and overlaps the first cylindrical lenses and the second cylindrical lenses.

10. 8. The backlight according to claim 7, The reflector includes a plurality of reflectors, A backlight, wherein each of the plurality of light sources is between an adjacent pair of the plurality of reflectors.

11. 2. The backlight according to claim 1, The reflector includes a pair of reflectors, The pair of reflectors are on either side of the light source in the second direction.

12. A backlight according to claim 1; A transmissive display panel; A display device having the above configuration.

Images