Display device with a plurality of light guides in a one-to-one correspondence with a plurality of displays

A display device includes a translucent front plate, a plurality of display panels, and a backlight unit. The backlight unit includes a plurality of light guide plates and a light source that causes light to be incident on the light guide plates. Each of the display panels is bonded to the front plate and smaller than the front plate. The light guide plates are disposed facing the respective display panels in one-to-one correspondence.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from Japanese Patent Application No. 2018-049945 filed on Mar. 16, 2018 and International Patent Application No. PCT/JP2019/010380 filed on Mar. 13, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

What is disclosed herein relates to a display device.

2. Description of the Related Art

As disclosed in Japanese Patent Application Laid-open Publication No. 2016-136520 or Japanese Patent Application Laid-open Publication No. 2013-242525, it is known that there are display devices including a display panel bonded to a front plate having a curved surface.

In recent years, display devices have been expected to have a larger screen in some cases.

For the foregoing reasons, there is a need for a display device having a larger screen composed of a plurality of display panels.

SUMMARY

A display device according to an aspect of the present disclosure includes: a translucent front plate; a plurality of display panels each of which is bonded to the front plate and smaller than the front plate; and a backlight unit comprising a plurality of light guide plates disposed facing the respective display panels in one-to-one correspondence and a light source configured to cause light to be incident on the light guide plates.

DETAILED DESCRIPTION

Exemplary aspects (embodiments) to embody the present disclosure are described below in greater detail with reference to the accompanying drawings. The contents described in the embodiments are not intended to limit the present disclosure. Components described below include components easily conceivable by those skilled in the art and components substantially identical therewith. Furthermore, the components described below may be appropriately combined. What is disclosed herein is given by way of example only, and appropriate changes made without departing from the spirit of the present disclosure and easily conceivable by those skilled in the art naturally fall within the scope of the disclosure. To simplify the explanation, the drawings may possibly illustrate the width, the thickness, the shape, and other elements of each unit more schematically than the actual aspect. These elements, however, are given by way of example only and are not intended to limit interpretation of the present disclosure. In the present specification and the figures, components similar to those previously described with reference to previous figures are denoted by the same reference numerals, and detailed explanation thereof may be appropriately omitted.

In this disclosure, when an element is described as being “on” another element, the element can be directly on the other element, or there can be one or more elements between the element and the other element.

First Embodiment

FIG. 1is an exploded perspective view of a display device according to a first embodiment.FIG. 2is a plan view of the display device according to the first embodiment viewed from a front plate.FIG. 3is an explanatory diagram for explaining a multilayered state of a front plate, display panels, an optical sheet, and light guide plates of the display device according to the first embodiment.FIG. 3illustrates the multilayered state of a front plate11, display panels2, an optical sheet4, and light guide plates3on the section along line III-IIP ofFIG. 2.FIG. 4is a schematic diagram of a vehicle provided with the display device according to the first embodiment.

In the following description, an X-Y-Z rectangular coordinate system is used. The X-axis is parallel to the long side of the display panel2. The Y-axis is parallel to a line passing through both ends of the display panel2when viewed in the direction along the X-axis. The Z-axis is orthogonal to both the X-axis and the Y-axis. The direction along the X-axis is referred to as an X-direction, the direction along the Y-axis is referred to as a Y-direction, and the direction along the Z-axis is referred to as a Z-direction.

As illustrated inFIG. 1, a display device1according to the first embodiment includes the front plate11, the display panels2, the optical sheet4, and a backlight unit8including the light guide plates3and a light source5. The display device1according to the first embodiment further includes a front frame12and a back cover13. This structure forms a space surrounded by the front plate11, the front frame12, and the back cover13. This space houses the display panels2, the optical sheet4, and the backlight unit8.

While the first embodiment exemplifies the front frame12and the back cover13, the housing of the display device1is not limited to the shape defined by the front frame12or the back cover13. The back cover13according to the first embodiment has a structure that can support the light guide plates3. Therefore, if the display device1is disposed with the Z-axis extending along the vertical direction, the weight of the light guide plates3is less likely to act on the display panels2as stress. To support the light guide plates3, the back cover13is made of metal material.

The front plate11is a cover member that protects the display panels2. The front plate11is made of glass, for example. The display panels2are bonded to the front plate11with an adhesive layer, which is not illustrated, interposed therebetween. As illustrated inFIG. 2, the front plate11has a rectangular shape when viewed from the front.

As illustrated inFIG. 3, the front plate11is curved as a whole with curvature R1. In this manner, the front plate11has a curved part. The front plate11is made of translucent glass or synthetic resin. A viewer can see video that appears to be displayed on a display surface along the surface of the front plate11.

The display panel2is a liquid crystal panel, for example. The display panel2includes a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate. The first substrate and the second substrate are made of glass, for example. The first substrate and the second substrate are each provided with an optical film, such as a polarization plate. The display panels2are bonded to the front plate11, thereby being curved along the curvature of the surface of the front plate11. Both ends of the front plate11in the X-axis direction are closer to the viewer than the center part is when viewed from the viewer.

As illustrated inFIG. 2, four display panels2are bonded to the front plate11. The display panel2is smaller than the front plate11in planar view. The number of display panels2bonded to the front plate11simply needs to be more than one. As the number of display panels2increases, the display device1can have a larger screen.

VGA indicates a resolution of 640×480 pixels on display disposed in a matrix (row-column configuration). WVGA indicates a resolution of 800×480 pixels on display disposed in a matrix. Quarter HD (qHD) indicates a resolution of 960×540 pixels on display disposed in a matrix. 720 HD indicates a resolution of 1280×720 pixels on display disposed in a matrix. Full-HD indicates a resolution of 1920×1080 pixels on display disposed in a matrix. Full-HD indicates a resolution of 2560×1600 pixels on display disposed in a matrix. The display panels2corresponding to the respective display regions20A,20B,20C, and20D may have different specifications in response speed. At least one of the display panels2corresponding to the respective display regions20A,20B,20C, and20D may include a touch panel. The touch panel may use part of wiring of the display panel2to implement its functions. The touch panel may be externally provided to the display panel2and disposed between the front plate11and the display panel2.

The display panels2corresponding to the respective display regions20A,20B,20C, and20D may have different specifications of switching elements. Of the display panels2corresponding to the respective display regions20A,20B,20C, and20D, at least one display panel may be provided with a switching element made of low-temperature polycrystalline silicon, and the other display panels may be provided with switching elements made of amorphous silicon.

As illustrated inFIG. 4, the display device1is mounted on a dashboard101of a vehicle100, for example. In this use example, the display device1has the advantage that the shape of the front plate11of the display device1smoothly fits to the curved interior of the dashboard101because the surface of the front plate11is curved. The display regions20A,20B,20C, and20D each display any one of a navigation system, a speedometer, a tachometer, a fuel gauge, and a water-temperature gauge, for example.

The vehicle100according to the first embodiment is a right-hand drive vehicle. The display regions closer to a steering wheel102are the display regions20C and20D.

As illustrated inFIG. 1, the light source5includes a plurality of light emitting elements7and a flexible substrate6. The light emitting elements7are arrayed on the flexible substrate6such that they are disposed facing one side surface of the light guide plates3.FIG. 5is a plan view of the light source according to the first embodiment. As illustrated inFIG. 5, the flexible substrate6is curved as a whole so as to extend along the curvature R1(refer toFIG. 3) of the front plate11. The light emitting elements7are arrayed along the side surface of the light guide plates3illustrated inFIG. 1. The flexible substrate6may have a rectangular shape, and the light emitting elements7may be arrayed along the side surface of the light guide plates3illustrated inFIG. 1.

The light emitting elements7disposed in a region LA illustrated inFIG. 5emit light to the light guide plate3disposed in the region LA illustrated inFIG. 3. The light guide plate3in the region LA illustrated inFIG. 3is disposed in one-to-one correspondence with the display panel2corresponding to the display region20A illustrated inFIG. 2. The light emitting elements7disposed in a region LB illustrated inFIG. 5emit light to the light guide plate3disposed in the region LB illustrated inFIG. 3. The light guide plate3in the region LB illustrated inFIG. 3is disposed in one-to-one correspondence with the display panel2corresponding to the display region20B illustrated inFIG. 2.

Similarly, the light emitting elements7disposed in a region LC illustrated inFIG. 5emit light to the light guide plate3disposed in the region LC illustrated inFIG. 3. The light guide plate3in the region LC illustrated inFIG. 3is disposed in one-to-one correspondence with the display panel2corresponding to the display region20C illustrated inFIG. 2. The light emitting elements7disposed in a region LD illustrated inFIG. 5emit light to the light guide plate3disposed in the region LD illustrated inFIG. 3. The light guide plate3in the region LD illustrated inFIG. 3is disposed in one-to-one correspondence with the display panel2corresponding to the display region20D illustrated inFIG. 2.

As illustrated inFIG. 1, the light guide plates3are aligned in the X-axis direction, thereby efficiently emitting light to the respective display panels2without any curved surface part on the emitting surface. With this configuration, the light guide plates3can each have a flat emitting surface facing the corresponding display panel2. As a result, the manufacturing cost of the light guide plates3can be reduced.

If the four light guide plates3are integrated, the integrated one has a heavier weight, which makes it difficult to assemble. By contrast, the light guide plates3according to the first embodiment are disposed in one-to-one correspondence with the respective display panels2. With this configuration, the light guide plates3each have a lighter weight, which makes it easy to assemble.

The numbers of light emitting elements7disposed in the respective regions LA, LB, LC, and LD according to the first embodiment are equal to one another. The gaps between adjacent pairs of the light emitting elements7in the regions LA, LB, LC, and LD are formed at the same pitch.

As illustrated inFIG. 3, the display device1includes the light guide plates3disposed in one-to-one correspondence with the respective display panels2in the regions LA, LB, LC, and LD. As illustrated inFIG. 3, pairs of the light guide plate3and the display panel2sandwich the common optical sheet4at the respective positions of the regions LA, LB, LC, and LD.

The gaps between adjacent pairs of the light guide plates3are filled with a filler31made of translucent optical resin or translucent silicone resin. This structure suppresses reduction in luminance between the light guide plates3. The filler31has a buffering function of preventing the light guide plates3from coming into contact with each other and making an unusual sound if vibrations are transmitted to the display device1. The use of translucent silicone resin for the filler31improves the function of suppressing an unusual sound against vibrations because the elastic modulus of silicone resin is higher than that of optical resin.

The optical sheet4includes a luminance enhancement film41and a light diffusion film42. The luminance enhancement film41has a function of enhancing the luminance level of emission light from the backlight unit8.

The light diffusion film42also covers the gaps between the adjacent pairs of the light guide plates3.FIG. 6is a plan view for explaining the light diffusion film of the optical sheet according to the first embodiment. As illustrated inFIG. 6, the light diffusion film42has regions43A,43B,43C, and43D and regions44in one film. In the light diffusion film42, the regions43A,43B,43C, and43D correspond to the display regions20A,20B,20C, and20D, respectively, illustrated inFIG. 2. In other words, the regions43A,43B,43C, and43D cover the emitting surfaces of the light guide plates3.

As described above, the display device1according to the first embodiment includes the translucent front plate11, the display panels2, and the backlight unit8. The backlight unit8includes the light guide plates3and the light source5that causes light to be incident on the light guide plates3. The display panels2are bonded to the front plate11and are smaller than the front plate11. The light guide plates3are disposed facing the respective display panels2in one-to-one correspondence.

This configuration has no emitting surface of the light guide plates3between the aligned display panels2, thereby making the boundaries between the display regions20A,20B,20C, and20D less likely to be visually recognized. As a result, the display device1can have a larger screen composed of the display panels2.

The haze of at least the region44illustrated inFIG. 6is higher than that of any one of the regions43A,43B,43C, and43D. The haze can be appropriately changed by changing the printing density of a light diffuser added to a translucent base material. The haze can be measured based on Plastics—Determination of haze for transparent materials (JIS K 7136).

As illustrated inFIG. 3, the difference between partial hazes of the optical sheet4is affected by the difference between partial hazes of the light diffusion film42because the luminance enhancement film41and the light diffusion film42overlap each other. Consequently, the optical sheet4covering the gaps between the adjacent light guide plates3has a higher haze than the regions of the optical sheet4covering the emitting surfaces facing the display panels2. This configuration further makes the boundaries between the display regions20A,20B,20C, and20D less likely to be visually recognized. As a result, the display device1can have a larger screen composed of the display panels2.

The hazes of the regions43A,43B,43C, and43D illustrated inFIG. 6may be equal to or different from one another. When the display regions20A,20B,20C, and20D have different resolutions, for example, it is possible, by setting the hazes of the regions43A,43B,43C, and43D illustrated inFIG. 6to appropriate different values, to adjust the tones of the display regions20A,20B,20C, and20D uniformly.

While the curved part of the front plate11is curved as a whole with the curvature R1, for example, the present embodiment is not limited thereto. In a front plate according to another aspect, for example, a curved surface part having a first curvature and a curved surface part having a second curvature different from the first curvature may be coupled by a coupling member. Alternatively, in a front plate according to another aspect, the curved surface part having the second curvature may be a concave surface when viewed from the display panel2if the curved surface part having the first curvature is a convex surface, and the curved surface part having the second curvature may be a convex surface when viewed from the viewer if the curved surface part having the first curvature is a concave surface.

Second Embodiment

FIG. 7is a plan view of the light source according to a second embodiment. In the description of the second embodiment, the same components as those according to the first embodiment are denoted by the same reference numerals, and detailed explanation thereof is omitted. The display device according to the second embodiment is different from the display device1according to the first embodiment only in the light source5illustrated inFIG. 7.

As illustrated inFIG. 3, the front plate11is curved as a whole with the curvature R1. Consequently, both ends of the front plate11in the X-axis direction are closer to the viewer than the center part is when viewed from the viewer. As illustrated inFIG. 1, the normal directions of the light guide plates3face the center of the front plate11in the X-axis direction. As a result, the amount of light emitted from the light guide plates3is likely to be larger in the center part of the front plate11in the X-axis direction than in both end parts of the front plate11in the X-axis direction.

As illustrated inFIG. 7, the light source5according to the second embodiment is configured such that the area density of the light emitting elements7disposed in the regions LA and LD is higher than that of the light emitting elements7disposed in the regions LB and LC. This configuration can increase the amount of light emitted from the light guide plates3in the regions LA and LD positioned at both ends of the front plate11in the X-axis direction.

As described above, the light source5includes the light emitting elements7. As illustrated inFIG. 1, the front plate11has a curved part in which both end parts in one direction are closer to the viewer than the center part is when viewed from the viewer. The area density of the light emitting elements7that cause light to be incident on the light guide plates3facing the display panels2positioned at both end parts is higher than that of the light emitting elements7that cause light to be incident on the light guide plates3facing the display panels2positioned at the center part. As a result, the distribution of the amount of light in the regions LA, LB, LC, and LD is less likely to be recognized as unevenness in luminance by the viewer.

As illustrated inFIG. 7, in the light source5according to the second embodiment, gaps P3between adjacent pairs of the light emitting elements7disposed in the regions LA and LD are equal. By contrast, the gaps between adjacent pairs of the light emitting elements7disposed in the regions LB and LC become larger as they are closer to the center corresponding to the boundary between the region LB and the region LC. Specifically, a gap P1between an adjacent pair of the light emitting elements7is larger than a gap P2between an adjacent pair of the light emitting elements7. The gap P2between the adjacent light emitting elements7is larger than the gap P3between the adjacent light emitting elements7.

In other words, the light source5has the light emitting elements7arrayed such that the gaps between the adjacent pairs of the light emitting elements7become larger as they are closer to the center part from both end parts of the front plate11. In this manner, the gaps between the adjacent pairs of the light emitting elements7disposed in the regions LB and LC are formed at irregular pitches. As a result, the distribution of the amount of light is less likely to be recognized as unevenness in luminance by the viewer also in the regions LB and LC.

Third Embodiment

FIG. 8is a plan view of the light source according to a third embodiment. In the description of the third embodiment, the same components as those according to the first embodiment are denoted by the same reference numerals, and detailed explanation thereof is omitted. The display device according to the third embodiment is different from the display device1according to the first embodiment only in the light source5illustrated inFIG. 8.

As illustrated inFIG. 4, the vehicle100is a right-hand drive vehicle, and the display regions closer to the steering wheel102are the display regions20C and20D. In this specifications, the display regions20C and20D may possibly be expected to have higher visibility than the display regions20A and20B.

For this reason, the amount of light emitted from the light guide plates3at the right part of the front plate11in the X-axis direction is made larger than the amount of light emitted from the light guide plates3at the left part when viewed from the viewer.

As illustrated inFIG. 8, the light source5of the display device according to the third embodiment is configured such that the area density of the light emitting elements7disposed in the regions LC and LD is higher than that of the light emitting elements7disposed in the regions LA and LB. The front plate11is mounted on the dashboard101of the vehicle100. In this case, the number of light emitting elements7of the light source5corresponding to the display regions20C and20D closer to the steering wheel102of the vehicle100is larger than the number of light emitting elements7of the light source5corresponding to the display regions20A and20B farther away from the steering wheel102. This configuration can increase the amount of light emitted from the light guide plates3in the regions LC and LD positioned at the right part of the front plate11in the X-axis direction. This facilitates the viewer's recognizing the display regions20C and20D.

If the vehicle100is a left-hand drive vehicle, and the display regions closer to the steering wheel102are the display regions20A and20B, the light source5is configured such that the area density of the light emitting elements7disposed in the regions LA and LB is higher than that of the light emitting elements7disposed in the regions LC and LD.

Fourth Embodiment

FIG. 9is a plan view of the light source according to a fourth embodiment. In the description of the fourth embodiment, the same components as those according to the first embodiment are denoted by the same reference numerals, and detailed explanation thereof is omitted. The display device according to the fourth embodiment is different from the display device1according to the first embodiment only in the light source5illustrated inFIG. 9.

In the display device according to the fourth embodiment, required luminance varies among the display regions20A,20B,20C, and20D illustrated inFIG. 2. In the fourth embodiment, higher luminance is required in order of the display region20D, the display region20B, the display region20C, and the display region20A.

In the display device according to the fourth embodiment, the light source5illustrated inFIG. 9has a smaller area density of the light emitting elements7in order of the region LD, the region LB, the region LC, and the region LA. As a result, the number of light emitting elements7that cause light to be incident on one plate of an adjacent pair of the light guide plates3is different from the number of light emitting elements7that cause light to be incident on the other plate of the adjacent pair of the light guide plates3. With this configuration, the amount of light emitted from the light guide plates3can be made smaller in order of the display region20D, the display region20B, the display region20C, and the display region20A. As a result, the video is displayed with the luminance required in the display regions20A,20B,20C, and20D, thereby facilitating the viewer's recognizing the video.

Modification of Fourth Embodiment

FIG. 10is a plan view of the light source according to a modification of the fourth embodiment. In the description of the modification of the fourth embodiment, the same components as those according to the fourth embodiment are denoted by the same reference numerals, and detailed explanation thereof is omitted. The display device according to the modification of the fourth embodiment is different from the display device1according to the first embodiment only in the light source5illustrated inFIG. 10.

The light source5illustrated inFIG. 10includes a plurality of flexible substrates6A,6B,6C, and6D. The flexible substrates6A,6B,6C, and6D are disposed in one-to-one correspondence with the respective light guide plates3.

With this configuration, the flexible substrates6A,6B,6C, and6D can be independently controlled. Also in the modification of the fourth embodiment, in a manner similar to the fourth embodiment, higher luminance is required in order of the display region20D, the display region20B, the display region20C, and the display region20A. In the modification of the fourth embodiment, while the area density of the light emitting elements7varies, the amounts of electric power supplied to the respective flexible substrates6A,6B,6C, and6D are adjusted. Consequently, it is possible to adjust more precisely the amount of light emitted from the light emitting elements7of the light source5disposed on the flexible substrates6A,6B,6C, and6D in accordance with the required luminance.

Out of other advantageous effects provided by the aspects described in the embodiments above, advantageous effects clearly defined by the description in the present specification or appropriately conceivable by those skilled in the art are naturally provided by the present aspects. The embodiments above may be appropriately combined.