JP2020191175A - Lighting device and display device - Google Patents

Abstract

To provide a lighting device which enables improvement of brightness of illumination light, and to provide a display device in which the lighting device is incorporated.SOLUTION: A lighting device includes: a sheet-like diffusion part; and light sources separated from each other. The light sources are disposed on a plane and face the diffusion part in a first direction. The diffusion part has: a first part which overlaps with the light sources in the first direction; and a second part which does not overlap with the light sources in the first direction. A thickness as seen in the first direction of the diffusion part is smaller in the second part than in the first part.SELECTED DRAWING: Figure 4

Description

Embodiments of the present invention relate to lighting devices and display devices.

In recent years, a liquid crystal display device using a liquid crystal panel for display has been known as a display device mounted on a television, an information device, or the like. Due to the display quality of such liquid crystal display devices, there is an increasing demand for higher brightness of lighting devices used in liquid crystal display devices, and direct lighting in which a light source is arranged directly under the liquid crystal panel with a light guide plate in between. The device is under consideration.

Japanese Unexamined Patent Publication No. 2008-96765

An object of the present embodiment is to provide a lighting device capable of improving the brightness of illumination light and a display device incorporating the lighting device.

According to this embodiment
A sheet-shaped diffuser and a plurality of light sources that are separated from each other are provided, and the plurality of light sources are arranged on a plane and face the diffuser in a first direction, and the diffuser is a plurality of light sources in the first direction. It has a first part that overlaps with the light source of the above and a second part that does not overlap with the plurality of light sources in the first direction, and the thickness of the diffusion part in the first direction is higher than that of the first part. A thin lighting device is provided in two parts.

According to this embodiment
It has a wiring board, a plurality of light sources arranged on the wiring board, a transparent layer covering the plurality of light sources, a wavelength conversion sheet, and a diffuser having a first main surface, and the wiring board and the wavelength. The conversion sheet and the diffusing portion overlap in the first direction, the plurality of light sources and the first main surface face each other in the first direction, and the diffusing portion overlaps the light source in the first direction. A display having a portion and a second portion that does not overlap with the light source in the first direction, and the thickness of the first portion in the first direction is thicker than the thickness of the second portion in the first direction. Equipment is provided.

FIG. 1 is a schematic view of a display device including the lighting device of one embodiment. FIG. 2 is a plan view of the lighting device shown in FIG. FIG. 3 is a cross-sectional view of a first configuration example of the display device of the present embodiment. FIG. 4 is a cross-sectional view of a second configuration example of the display device of the present embodiment. FIG. 5 is a plan view of the diffusion portion shown in FIG. FIG. 6 is a cross-sectional view of a third configuration example of the display device of the present embodiment. FIG. 7 is a plan view of the diffusion portion shown in FIG.

Hereinafter, the present embodiment will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention are naturally included in the scope of the present invention. Further, in order to clarify the description, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment, but this is merely an example, and the present invention It does not limit the interpretation. Further, in the present specification and each figure, components exhibiting the same or similar functions as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and duplicate detailed description may be omitted as appropriate. ..

FIG. 1 is a schematic view of a display device DSP including the lighting device IL of one embodiment. In one example, the directions X, Y and Z are orthogonal to each other, but may intersect at an angle other than 90 degrees. The direction Z corresponds to the thickness direction of the display device DSP. In the present specification, the position on the tip side of the arrow indicating the direction Z is referred to as an upper position, and the position on the opposite side of the arrow tip is referred to as a lower position. Further, it is assumed that there is an observation position for observing the display device DSP on the tip side of the arrow indicating the direction Z, and viewing from this observation position toward the XY plane defined by the direction X and the direction Y is a plan view. That is.
As shown in FIG. 1, the display device DSP includes a display panel PNL and a lighting device IL. The display device DSP is a display device that requires a light source independent of the display panel PNL of, for example, a liquid crystal display device. The display panel PNL is, for example, a transmissive display panel PNL having a transmissive display function for displaying an image by selectively transmitting light from the lower side of the display panel PNL. The illuminating device IL illuminates the display panel PNL with the illuminating light L emitted from the illuminating device IL.

FIG. 2 is a plan view of the lighting device IL shown in FIG.
As shown in FIG. 2, the illuminating device IL includes a wiring board F1 and a plurality of light sources EM.
The wiring board F1 is, for example, a bendable flexible printed circuit board. The wiring board F1 may be a hard printed wiring board. The wiring board F1 has a mounting area MA. The mounting area MA is, for example, a plane parallel to the XY plane. The mounting area MA is divided into a plurality of segments SG. The plurality of segments SG are located in a matrix in the direction X and the direction Y. In one example, the mounting area MA is divided into 30 segment SGs along the direction X and 32 segments SGs along the direction Y. That is, the mounting area MA is divided into 960 segment SGs. As shown enlarged in FIG. 2, the illuminating device IL includes, for example, four light source EMs in one segment SG. The illuminating device IL shown in FIG. 2 includes 3840 light source EMs.

The plurality of light source EMs are individually separated from each other and are arranged at equal intervals in each of the direction X and the direction Y. The light source EM is, for example, a light emitting diode (LED) having no phosphor, and emits blue illumination light. The area of the light emitting surface of the light source EM is, for example, an area of 0.3 mm × 0.3 mm or less in a plan view. The light source EM is arranged in the mounting area MA of the wiring board F1. As an example, the light source EM is connected to the wiring board F1 via a conductive adhesive containing conductive particles.

FIG. 3 is a cross-sectional view of a first configuration example of the display device DSP of the present embodiment.
As shown in FIG. 3, the illuminating device IL further includes a transparent layer OC, a wavelength conversion sheet TS, a diffuser SSS, a prism sheet PS1, and a prism sheet PS2. In the direction Z, the diffuser SSS, the wavelength conversion sheet TS, and the wiring board F1 overlap each other.

The light source EM is located between the wiring board F1 and the display panel PNL. The light source EM is located on the wiring board F1 and faces the diffuser SSS in the direction Z. The transparent layer OC covers a plurality of light sources EM and is in contact with the wiring board F1. The transparent layer OC is, for example, a transparent organic insulating layer.

The wavelength conversion sheet TS is located between the plurality of light sources EM and the diffuser SSS. The wavelength conversion sheet TS is in contact with the transparent layer OC and covers the transparent layer OC. In the illustrated example, the wavelength conversion sheet TS and the transparent layer OC are in close contact with each other, and there is no gap between the wavelength conversion sheet TS and the transparent layer OC. The wavelength conversion sheet TS absorbs the light emitted from the light source EM and emits light having a wavelength longer than the wavelength of the absorbed light. The wavelength conversion sheet TS includes, for example, quantum dots as a light emitting material, but is not limited to this, and may include a material that emits fluorescence or phosphorescence. The wavelength conversion sheet TS has a thickness of 100 μm to 200 μm in the direction Z as an example.

In one example, the light source EM emits light of blue wavelength (excitation light). The wavelength conversion sheet TS absorbs the excitation light and emits yellow light. Therefore, white illumination light is generated in which yellow light, which is converted light, and blue light, which is unconverted light, are mixed.
In another example, the light source EM emits light of ultraviolet wavelength (excitation light). The wavelength conversion sheet TS absorbs the excitation light and emits light in blue, green, and red, respectively, to generate white illumination light.

The diffuser SSS is located between the wavelength conversion sheet TS and the display panel PNL and between the light source EM and the display panel PNL, and has a thickness T1. The diffusion unit SSS has a main surface MF facing the display panel PNL in the direction Z. In the illustrated example, the diffusion unit SSS is a sheet-like diffusion unit SSS formed by a plurality of diffusion sheet SSs (SS1 to SS3). The diffusion portion SSS may be formed by a plurality of diffusion plates SS. The diffusion sheet SS diffuses the light incident on the diffusion sheet SS to make the brightness of the light uniform. The diffusion sheet SS has a thickness of 50 μm to 100 μm in the direction Z as an example. The diffusion sheets SS1, SS2 and SS3 are laminated on the wavelength conversion sheet TS in this order in the direction Z. The thickness T1 is equal to the sum of the thicknesses of the diffusion sheets SS1, SS2 and SS3, respectively.

The prism sheets PS1 and PS2 are located between the diffuser SSS and the display panel PNL. The prism sheets PS1 and PS2 are laminated on the diffusion portion SSS. The prism sheets PS1 and PS2 collect the light diffused by the diffusing unit SSS in the direction Z.

According to the first configuration example, since there is no gap between the wavelength conversion sheet TS and the transparent layer OC, the thickness of the illuminating device IL in the direction Z can be reduced.

In addition, the optical path of the light emitted from the light source EM to the display panel PNL is shortened, the respective lights from the adjacent light source EM are not sufficiently mixed, and streak-like unevenness due to the difference in brightness of the light is visually recognized. There is a risk. According to the present embodiment, the diffusion portion SSS formed by the three diffusion sheets SS is located between the wavelength conversion sheet TS and the display panel PNL. As a result, the light emitted from the light source EM is diffused by the diffusing unit SSS, and the brightness of the light is made uniform, so that deterioration of the lighting quality of the lighting device IL due to the difference in the brightness of the light can be suppressed.

FIG. 4 is a cross-sectional view of a second configuration example of the display device DSP of the present embodiment.
As shown in FIG. 4, the second configuration example differs from the first configuration example shown in FIG. 3 in that the diffusion sheet SS1 has a plurality of through holes TH penetrating in the direction Z. ing. The through hole TH is provided at a position that does not overlap the light source EM in the direction Z. The through hole TH may not be provided in the diffusion sheet SS1 but may be provided in the diffusion sheet SS2 or SS3. The through hole TH corresponds to, for example, an air layer having no member.

The diffusion unit SSS has a first part SSS1 and a second part SSS2. The first part SSS1 has a thickness T1 and overlaps a plurality of light source EMs in the direction Z. The first part SSS1 has a first surface FS1 facing the light source EM in the direction Z. In the illustrated example, the lower surface of the diffusion sheet SS1 corresponds to the first surface FS1.
The second part SSS2 has a thickness T2 and does not overlap the light source EM in the direction Z. The second part SSS2 overlaps the through hole TH in the direction Z. In the illustrated example, the thickness T2 is the sum of the thickness of the diffusion sheet SS2 and the thickness of the diffusion sheet SS3, and is thinner than the thickness T1. The difference between the thickness T1 and the thickness T2 is the thickness of the diffusion sheet SS1. The difference between the thickness T1 and the thickness T2 may be greater than or equal to the thickness of the diffusion sheet SS1 as long as the thickness T2 does not reach 0 μm. Further, it can be said that the difference between the thickness T1 and the thickness T2 may be equal to or larger than the thickness of one of the plurality of diffusion plates SS.
The diffusion sheet SS1 is in contact with the wavelength conversion sheet TS in the first part SSS1 and has a plurality of through holes TH in the second part SSS2. The diffusion sheets SS2 and SS3 are located between the diffusion sheet SS1 and the prism sheet PS1, respectively. The diffusion sheets SS2 and SS3 cover the through hole TH in the second part SSS2. The lighting device IL has an air layer (through hole TH) between the wavelength conversion sheet TS and the second part SSS2.
The main surface MF of the diffusion unit SSS corresponds to each of the upper surface facing the display panel PNL in the first part SSS1 and the upper surface facing the display panel PNL in the second part SSS2. The main surface MF faces a plurality of light sources EM in the direction Z.

FIG. 5 is a plan view of the diffusion portion SSS shown in FIG. FIG. 5 is a plan view from the diffusion portion SSS toward the light source EM, and the diffusion sheets SS2 and SS3 are shown by alternate long and short dash lines. Further, the wavelength conversion sheet TS and the transparent layer OC are not shown.
As shown in FIG. 5, the plurality of through holes TH are located between the light source EM and the light source EM. In the illustrated example, the through holes TH are arranged at equal intervals along the direction X and are arranged at equal intervals in the direction Y. The through hole TH is circular in a plan view. The through hole TH may be a polygon other than an ellipse or a circle.

Here, we focus on one segment SG. The main surface MF of the diffuser SSS is located over the entire segment SG. The first surface FS1 overlaps the light source EM and corresponds to the region of the first part SSS1 in a plan view. The through hole TH corresponds to the region of the second part SSS2 in a plan view. As an example, the area of the first surface FS1 is 50% or less of the area of the main surface MF. In other words, the area of the through hole TH is 50% or more of the area of the main surface MF.

In the second configuration example, the diffusion sheet SS1 corresponds to the first diffusion sheet, the diffusion sheet SS2 corresponds to the second diffusion sheet, the diffusion sheet SS3 corresponds to the third diffusion sheet, and the thickness T1 corresponds to the first thickness. The thickness T2 corresponds to the second thickness, and the direction Z corresponds to the first direction.

In such a second configuration example, the same effect as that of the above configuration example can be obtained.
Further, the diffusion sheet diffuses the light incident on the diffusion sheet to make the brightness of the light uniform, but when a plurality of diffusion sheets or thick diffusion sheets are used, the brightness of the light tends to decrease. According to the second configuration example, the diffusion portion SSS has a first portion SSS1 having a thickness T1 and a second portion SSS2 having a thickness T2 smaller than the thickness T1. As a result, it is possible to suppress a decrease in the brightness of the light traveling through the diffusion unit SSS as compared with the diffusion unit SSS having a constant thickness T1, and the brightness of the illumination light L emitted from the illumination device IL is improved. Can be made to. Further, the first part SSS1 overlaps the light source EM in the direction Z, and the second part SSS2 does not overlap the light source EM in the direction Z. The brightness of the light incident on the first part SSS1 overlapping the light source EM is larger than the brightness of the light incident on the second part SSS2 not overlapping the light source EM. Since the first part SSS1 is thicker than the second part SSS2, the high-intensity light incident on the first part SSS1 is more diffused than the low-intensity light incident on the second part SSS2, and the first part SSS1 The difference between the brightness of the light emitted from the light and the brightness of the light emitted from the second part SSS2 can be alleviated, and the deterioration of the lighting quality of the lighting device IL due to the difference in the brightness of the light can be suppressed. ..

Further, the diffusion sheet SS1 has a through hole TH. Therefore, the through hole TH is less likely to be visually recognized as compared with the case where the through hole TH is provided in the diffusion sheet SS2 or SS3. Further, the diffusion sheet SS2 and the diffusion sheet SS3 each cover the through hole TH of the diffusion sheet SS1. As a result, it is possible to further suppress the visibility of the through hole TH. Further, by changing the size of the through hole TH, the ratio of the area of the through hole TH to the area of the main surface MF in the plan view is adjusted, and the brightness of the illumination light L emitted from the illumination device IL is adjusted. Can be done. As an example, increasing the ratio of the area of the through hole TH to the area of the main surface MF in a plan view increases the brightness of the illumination light L emitted from the illumination device IL.

Further, the diffusion portion SSS is formed by laminating the diffusion sheets SS1 to SS3. Therefore, as compared with the case of manufacturing a special diffusion sheet having different thicknesses such as the thicknesses T1 and T2, the manufacturing process is simple and mass production can be easily performed.

FIG. 6 is a cross-sectional view of a third configuration example of the display device DSP of the present embodiment.
As shown in FIG. 6, the third configuration example is different from the second configuration example shown in FIG. 4 in that the diffusion portion SSS is formed by one diffusion sheet SS4. The diffusion sheet SS4 has a plurality of openings OP. The opening OP is provided at a position that does not overlap with the light source EM. The opening OP is a portion recessed from the lower surface to the upper surface of the diffusion sheet SS4 in the direction Z. The second part SSS2 overlaps the opening OP. In the illustrated example, the upper surface of the diffusion sheet SS4 corresponds to the main surface MF. In the diffusion sheet SS4, the surface in contact with the wavelength conversion sheet TS corresponds to the first surface FS1.

FIG. 7 is a plan view of the diffusion portion SSS shown in FIG. FIG. 7 is a plan view from the diffusion unit SSS (diffusion sheet SS4) toward the light source EM, and the wavelength conversion sheet TS and the transparent layer OC are not shown.
As shown in FIG. 7, the first surface FS1 is scattered at a position overlapping each light source EM. The first surface FS1 is a quadrangle in a plan view, but may be another polygon or a circle.

Here, we focus on one segment SG. The main surface MF of the diffuser SSS is located over the entire segment SG. The first surface FS1 overlaps the light source EM and corresponds to the region of the first part SSS1 in a plan view. The opening OP corresponds to the region of the second part SSS2 in a plan view. In the illustrated example, the opening OP is provided in a grid pattern surrounding the first surface FS1. As an example, the area of the first surface FS1 is 40% or less of the area of the main surface MF. In other words, the area of the through hole TH is 60% or more of the area of the main surface MF.

In such a third configuration example, the same effect as that of the above configuration example can be obtained.
As described above, according to the present embodiment, it is possible to provide a lighting device capable of improving the brightness of the lighting light and a display device incorporating the lighting device.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

DSP ... Display device PNL ... Display panel IL ... Lighting device
F1 ... Wiring board EM ... Light source OC ... Transparent layer TS ... Wavelength conversion sheet
SSS ... Diffusion part SSS1 ... Part 1 SSS2 ... Part 2 SS ... Diffusion sheet, diffusion plate
TH ... Through hole T1 ... 1st thickness T2 ... 2nd thickness
PS ... Prism sheet

Claims (9)

Sheet-shaped diffuser and
With multiple light sources, each separated
The plurality of light sources are arranged in a plane and face the diffuser in a first direction.
The diffusion portion has a first portion that overlaps the plurality of light sources in the first direction and a second portion that does not overlap the plurality of light sources in the first direction.
A lighting device in which the thickness of the diffusion portion in the first direction is thinner in the second portion than in the first portion. The lighting device according to claim 1, wherein the first part has a first surface facing the plurality of light sources. Further, a wavelength conversion sheet located between the plurality of light sources and the diffuser is provided.
The lighting device according to claim 1 or 2, which has an air layer between the wavelength conversion sheet and the second part. The diffusion portion is composed of a plurality of diffusion plates.
The lighting device according to claim 1, wherein the difference between the thickness of the first part and the thickness of the second part is equal to or more than the thickness of one of the plurality of diffusion plates. Wiring board and
A plurality of light sources arranged on the wiring board and
A transparent layer covering the plurality of light sources and
Wavelength conversion sheet and
It has a diffuser with a first main surface and
The wiring board, the wavelength conversion sheet, and the diffuser overlap in the first direction.
The plurality of light sources and the first main surface face each other in the first direction.
The diffusing portion has a first portion that overlaps the light source in the first direction and a second portion that does not overlap the light source in the first direction.
A display device in which the thickness of the first part in the first direction is thicker than the thickness of the second part in the first direction. The display device according to claim 5, wherein the first part has a first surface facing the light source in the first direction. The diffusion unit has a plurality of diffusion sheets and has a plurality of diffusion sheets.
The first diffusion sheet among the plurality of diffusion sheets is in contact with the wavelength conversion sheet in the first part, and has a plurality of through holes not overlapping with the light source in the second part. The display device according to 6. The display device according to claim 7, wherein the second diffusion sheet among the plurality of diffusion sheets covers the through hole in the second part. The display device according to claim 7, wherein the difference between the thickness of the first part and the thickness of the second part is equal to or larger than the thickness of the first diffusion sheet.

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