DISPLAY DEVICE

A display device includes: point light sources emitting light of different colors; light guides each of which includes an end face facing a corresponding one of the point light sources, a first surface connected to the end face, and a second surface diagonally facing the end face and the first surface, the light being incident on the end face and undergoing internal reflection, between the first and second surfaces, and linear pattern emission from the first surface; and a display panel including a side surface that faces the first surface and on which the light is incident, front and back surfaces, and a converter that changes a traveling direction of the light, for each pixel of the image, propagating away from the side surface internally between the front and back surfaces, to a direction toward the display surface.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese patent application JP2023-089958 filed on May 31, 2023, the contents of which are hereby incorporated by reference into this application.

BACKGROUND

The present disclosure relates to a display device.

2. Description of the Related Art

There is a display device that introduces light through a side surface of a display panel (JP2017-215510A). Full-color display without use of a color filter can be achieved by introducing light of the three primary colors individually and employing a field sequential method.

For introducing the light through the side surface of the display panel, a surface light source cannot be used (JP2008-210758A). For introducing the light individually for each of the three primary colors, a white linear light source cannot be used (JP2009-259557A). Point light sources of different colors arranged in a row, when they emit light for each color, cannot emit light in a linear pattern because of gaps between the point light sources of the same color.

SUMMARY

This disclosure aims to enable light of multiple colors, emitted in a linear pattern, to be incident on a side surface of a display panel for each color.

A display device includes: point light sources emitting light of different colors from each other; light guides, each of the light guides including an end face facing a corresponding one of the point light sources, each of the light guides including a first surface connected to the end face, each of the light guides including a second surface diagonally facing the end face and the first surface, the light being incident on the end face and undergoing internal reflection, between the first surface and the second surface, and linear pattern emission from the first surface; and a display panel including a side surface that faces the first surface and on which the light is incident, the display panel including a front surface and a back surface, at least one of the front surface or the back surface being a display surface of an image, the display panel including a converter that changes a traveling direction of the light, for each pixel of the image, propagating away from the side surface internally between the front surface and the back surface, to a direction toward the display surface.

DETAILED DESCRIPTION

Hereinafter, some embodiments will be described with reference to the drawings. Here, the invention can be embodied according to various aspects within the scope of the invention without departing from the gist of the invention and is not construed as being limited to the content described in the embodiments exemplified below.

The drawings are further schematically illustrated in widths, thickness, shapes, and the like of units than actual forms to further clarify description in some cases but are merely examples and do not limit interpretation of the invention. In the present specification and the drawings, the same reference numerals are given to elements having the same functions described in the previously described drawings, and the repeated description will be omitted.

Further, in the detailed description, “on” or “under” in definition of positional relations of certain constituents, and other constituents includes not only a case in which a constituent is located just on or just under a certain constituent but also a case in which another constituent is interposed between constituents unless otherwise mentioned.

First Embodiment

FIG.1is a front view of a display device according to a first embodiment.FIG.2is a II-II cross-sectional view of the display device inFIG.1. The display device includes a display panel10(e.g., liquid crystal display panel). The display panel10includes a front surface12and a back surface13. At least one (for example, both) of the front surface12or the back surface13is a display surface of an image. The display panel10includes a side surface14on which light can be incident.

As shown inFIG.2, the display panel10includes a pair of transparent substrates16. A polymer-dispersed liquid crystal layer18is interposed between the pair of transparent substrates16. The liquid crystal layer18is located between pixel electrodes20and a common electrode22. The pixel electrodes20and the common electrode22are transparent. When no voltage is applied between the pixel electrodes20and the common electrode22, light travels straight through the liquid crystal layer18without changing the traveling direction of light.

FIG.3is a cross-sectional view of the display device during operation. A voltage is applied between the pixel electrode20A and the common electrode22, whereby light is scattered in the liquid crystal layer18. Thus, the traveling direction of light is converted, for each pixel of the image, to the direction toward the display surface (at least one of the front surface12or the back surface13). The liquid crystal layer18, the pixel electrodes20, and the common electrode22constitute a converter24. The display panel10includes the converter24. The converter24can convert the traveling direction of light, for each pixel of the image, propagating away from the side surface14internally between the front surface12and the back surface13to the direction toward the display surface (at least one of the front surface12or the back surface13).

FIG.4is a bottom view of the display device inFIG.1. The display device includes point light sources26R,26G,26B (e.g., light-emitting diodes). The point light sources26R,26G,26B can emit light of different colors from each other. The point light sources26R,26G,26B overlap along the thickness (direction between the front surface12and the back surface13) of the display panel10.

The display device includes light guides28. Each light guide28includes an end face30that faces a corresponding one of the point light sources26R,26G,26B. The light guide28includes a first surface32connected to the end face30. The light guide28includes a second surface34diagonally facing the end face30and the first surface32. The light is incident on the end face30and undergoes internal reflection within the light guide28between the first surface32and the second surface34, and linear pattern emission from the first surface32. The side surface14of the display panel10faces the first surface32, enabling light to be incident on it.

The end face30of each light guide28is parallel and adjacent to the end face30of another light guide28. The first surface32of each light guide28is parallel and adjacent to the first surface32of another light guide28. The second surface34of each light guide28is parallel and adjacent to the second surface34of another light guide28.

The light guides28are separated from each other. The light guides28overlap along the thickness of the display panel10. The light guides28are set in an arrangement maintaining gaps between adjacent ones of the light guides28. The sum of the thicknesses of the light guides28and the gaps is within (for example, equivalent to) the thickness of the display panel10.

The present embodiment enables light of multiple colors, from the point light sources26R,26G,26B, to be incident on the light guides28for each color, and enables linearly emitted light of multiple colors to be incident, separately for each color, on the side surface14of the display panel10.

FIGS.5A to5Dare explanatory diagrams of a generating method of a color image. In this embodiment, multiple monochromatic images of different colors are displayed in a time-division manner using a field sequential method. For example, a red image inFIG.5A, a green image inFIG.5B, and a blue image inFIG.5Care displayed in sequence. This results in a full-color image shown inFIG.5Dbeing visually recognizable due to afterimages of the multiple images. Overlapping areas of red, green, and blue images become white.

Second Embodiment

FIG.6is a front view of a display device according to a second embodiment.FIG.7is a bottom view of the display device inFIG.6. This embodiment differs from the first embodiment in that light guides are an integrated entity and constitute a single light guide228. Light of multiple colors from the respective point light sources226R,226G,226B is incident on the light guide228. The thickness of the single light guide228is within (for example, equivalent to) the thickness of the display panel210. The contents described in the first embodiment are applicable to other aspects.

Third Embodiment

FIG.8is a front view of a display device according to a third embodiment.FIG.9is a bottom view of the display device inFIG.8. The point light sources326R,326G,326B overlap along the normal line N to the side surface314of the display panel310. The light guides328overlap along the normal line N to the side surface314of the display panel310. The thickness of each light guide328is within (for example, equivalent to) the thickness of the display panel310. The contents described in the first embodiment are applicable to other aspects.

Outline of Embodiments

(1) A display device including:point light sources26R,26G,26B emitting light of different colors from each other; light guides28, each of the light guides28including an end face30facing a corresponding one of the point light sources26R,26G,26B, each of the light guides28including a first surface32connected to the end face30, each of the light guides28including a second surface34diagonally facing the end face30and the first surface32, the light being incident on the end face30and undergoing internal reflection, between the first surface32and the second surface34, and linear pattern emission from the first surface32; and a display panel10including a side surface14that faces the first surface32and on which the light is incident, the display panel10including a front surface12and a back surface13, at least one of the front surface12or the back surface13being a display surface of an image, the display panel10including a converter24that changes a traveling direction of the light, for each pixel of the image, propagating away from the side surface14internally between the front surface12and the back surface13, to a direction toward the display surface.

(2) The display device according to (1), wherein the point light sources26R,26G,26B overlap along a thickness of the display panel10.

(3) The display device according to (2), wherein the light guides28overlap along the thickness of the display panel10.

(4) The display device according to (3), wherein the light guides28are separated from each other.

(5) The display device according to (4), wherein the light guides28are set in an arrangement maintaining gaps between adjacent ones of the light guides28, and a sum of thicknesses of the light guides28and the gaps is within the thickness of the display panel10.

(6) The display device according to (3), wherein the light guides are an integrated entity and constitute a single light guide228.

(7) The display device according to (6), wherein a thickness of the single light guide228is within the thickness of the display panel210.

(8) The display device according to (1), wherein the point light sources326R,326G,326B overlap along a normal line N to the side surface314of the display panel310.

(9) The display device according to (8), wherein the light guides328overlap along the normal line N to the side surface314of the display panel310.

(10) The display device according to (9), wherein a thickness of each of the light guides328is within the thickness of the display panel310.

The embodiments described above are not limited and different variations are possible. The structures explained in the embodiments may be replaced with substantially the same structures and other structures that can achieve the same effect or the same objective.