Display device and head-mounted display apparatus

Abstract

To provide a technique capable of improving the quality of an image in a laminated light field type display device.SOLUTION: In a laminated light field type display device, a plurality of display panels are laminated by interposing a medium layer. The plurality of display panels include: a first display panel arranged farthest from an observer; and at least one second display panel, which is a display panel other than the first display panel, is transparent, and is driven by field sequential control.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a display device, and more particularly to a stacked light field type display device in which a plurality of display panels are stacked, and a head mounted display device. [Background technology]

[0002] In recent years, light field display devices (hereinafter referred to as light field display devices) that allow an observer to view a stereoscopic image have been attracting attention. Humans view an object when light reflected from the object enters the eyes. A light field display device reproduces this reflected light on a display panel, and is a display device that provides the sense of depth that humans view in the natural world.

[0003] A light field display device is a display device that allows humans to see a three-dimensional image by artificially reproducing a group of controlled light rays. One type of light field display device is a stacked light field display device. The stacked light field method is also called the tensor light field method.

[0004] For example, Patent Document 1 describes a stacked light field display device in which two liquid crystal display panels are stacked with a medium layer sandwiched between them. In the stacked light field display device of Patent Document 1, the first liquid crystal display panel arranged on the side farther from the observer is equipped with a backlight or the like and has a function of emitting light. The second liquid crystal display panel arranged on the side closer to the observer does not have a function of emitting light and is illuminated by the light emitted from the first liquid crystal display. A light ray emitted from a pixel of the first liquid crystal display panel passes through a pixel of the second liquid crystal display panel and enters the observer's eye. The light ray is controlled by the combination of pixels through which the light ray passes. Since the stacked light field display device is composed of multiple stacked display panels, it has a feature that a single light ray in the light field is expressed as the product of the transmittances of the multiple display panels or the sum of the brightness.

[0005] As a display device that displays a three-dimensional image by stacking a plurality of display panels, for example, Patent Document 2 describes a DFD (Depth-Fused 3-D) display device. In the DFD display device, the second display panel is illuminated by a backlight provided in the first display panel. By displaying a front image and a rear image of an object with varying brightness on the first display panel and the second display panel, respectively, the illusion that the front and rear images are fused into one image is created. The DFD display device does not control the light beam for each pixel, and is therefore technically different from a stacked light field display device. The DFD display device can only display an image in the space between the display panels, whereas the stacked light field display device can display an image up to the range outside the display panels. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2019 / 198784 [Patent Document 2] Patent No. 4444152 Summary of the Invention [Problem to be solved by the invention]

[0007] The stacked light field display device controls light rays by the product of the light transmittances of the respective display panels. Furthermore, the stacked light field display device uses a color filter type liquid crystal display (hereinafter referred to as color LCD) panel having a color filter and a polarizing plate. Usually, the light transmittance of a polarizing plate is about 1 / 2, and the light transmittance of a color filter is about 1 / 3. Therefore, the light transmittance of one color LCD is small, about 1 / 6. As described above, the stacked light field display device is composed of multiple stacked display panels. Therefore, when the display device has two color LCDs, the light transmittance is about 1 / 36, and when the display device has three color LCDs, the light transmittance is about 1 / 216, so that the light transmittance is greatly reduced. As a result, when the display device has multiple color LCDs, the image displayed by the display device becomes dark, which causes a problem of reduced image quality.

[0008] The inventors have made an invention to solve the above-mentioned problems occurring in conventional stacked light field display devices with color LCD panels.

[0009] An object of the present invention is to provide a technique capable of improving image quality in a stacked light field type display device. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention proposes the following means. A display device according to a first aspect of the present invention is a stacked light field type display device in which a plurality of display panels are stacked with a medium layer sandwiched between them, and is characterized in that the plurality of display panels include a first display panel that is arranged farthest from a viewer, and at least one second display panel that is a display panel other than the first display panel, is transparent, and is driven by field sequential control.

[0011] According to a second aspect of the present invention, the display device of the first aspect is characterized in that the first display panel is driven by time sequential control and has a light source that emits light of three or more colors including red, blue, and green, and the light source is driven to blink in synchronization with the second display panel.

[0012] According to a third aspect of the present invention, the display device according to the first aspect is characterized in that each of the plurality of display panels is driven by field sequential control and is driven to blink in synchronization with each other.

[0013] According to a fourth aspect of the present invention, the display device according to the first to third aspects is characterized in that the area of ​​the first display panel is the largest among the areas of the respective display panels.

[0014] According to a fifth aspect of the present invention, the display device according to the first to fourth aspects is characterized in that only the first display panel emits light or has a light source.

[0015] According to a sixth aspect of the present invention, in the display device according to the first to fifth aspects, the second display panel is a light-diffusing liquid crystal display panel.

[0016] A head mounted display device according to a seventh aspect of the present invention comprises a display device according to any one of the first to sixth aspects and an eyepiece, and is characterized in that the display device can be observed through the eyepiece.

[0017] According to an eighth aspect of the present invention, the head mounted display device according to the seventh aspect is characterized in that at least one of the display panels has a regular polygon shape having four or more corners.

[0018] According to a ninth aspect of the present invention, in the head mounted display device according to the seventh and eighth aspects, the first display panel is transparent. Effect of the Invention

[0019] The present invention contributes to improving the image quality in a stacked light field type display device. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view showing an image display device according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an image display device according to a first embodiment of the present invention. [Diagram 3] FIG. 11 is a schematic cross-sectional view showing a conventional image display device. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an image display device according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic cross-sectional view showing an image display device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view that illustrates a display device 1 according to the present embodiment. The display device 1 of the present embodiment is a stacked light field display device. The display device 1 includes a plurality of display panels 10, 20. In the present embodiment, the plurality of display panels 10, 20 include a first display panel 10 and a second display panel 20. As illustrated in FIG. 2, the display device 1 also includes a control unit 50. The control unit 50 is electrically connected to each of the first display panel 10 and the second display panel 20. The control unit 50 controls the operation of each of the first display panel 10 and the second display panel 20.

[0022] As shown in FIG. 1, the second display panel 20 side of the display device 1 is the front side, and the first display panel 10 side is the rear side. The viewer views an image displayed on the front side. Of the multiple display panels 10, 20, the first display panel 10 is disposed farthest from the viewer. The second display panel 20 is disposed closer to the front than the first display panel 10. The second display panel 20 is a display panel other than the first display panel 10. For example, when the display device 1 has three or more display panels, the first display panel 10 is the display panel disposed farthest from the viewer, and the second display panel 20 is a display panel other than the first display panel 10.

[0023] The first display panel 10 is a display panel driven by known time sequential control, such as a color LCD panel, an organic EL display panel, and an inorganic EL display panel. In this embodiment, the first display panel 10 is a color LCD panel. In the first display panel 10, a light guide plate 26, a diffusion plate 27, a polarizing plate 13a, a glass plate 25a, a liquid crystal layer 12a, a color filter 14, a glass plate 25b, and a polarizing plate 13b are arranged in this order from the rear side. The first display panel 10 has a light source 28. The light source 28 is arranged near the light guide plate 26. In this embodiment, the first display panel 10 has a light source 28 that emits light beams of three or more colors, red, blue, and green. The light source 28 is driven to blink in synchronization with the second display panel 20 by the control unit 50.

[0024] The second display panel 20 is a display panel driven by a known field sequential control. In the second display panel 20, a glass plate 25c, a liquid crystal layer 12b, and a glass plate 25d are arranged in this order from the rear side. The second display panel 20 has a structure generally similar to that of a display panel driven by a known field sequential control. In this embodiment, the second display panel 20 has a light source 29. The light source 29 is arranged near the glass plate 25c. In this embodiment, the second display panel 20 has a light source 29 that emits light beams of three or more colors, red, blue, and green. The second display panel 20 does not have optical members such as a color filter and a polarizing plate that are usually provided in a color LCD panel. As a result, the second display panel 20 is a transparent display panel. Therefore, the second display panel 20 is less likely to absorb, reflect, and diffuse light beams. Therefore, in this embodiment, the light transmittance of the second display panel 20 can be increased.

[0025] According to this embodiment, the multiple display panels include at least one second display panel 20, which is a display panel other than the first display panel 10, is transparent, and is driven by field sequential control. Therefore, the light transmittance of the second display panel 20 can be increased compared to when the second display panel 20 is a color LCD panel driven by time sequential control. Therefore, the brightness of the image visually recognized by the observer can be increased, and the quality of the image can be improved.

[0026] In the first display panel 10, which is a time-sequential display panel, one pixel is divided by a black matrix into three subpixels: a red subpixel 14R in which a red filter R is arranged, a green subpixel 14G in which a green filter G is arranged, and a blue subpixel 14B in which a blue filter B is arranged. In contrast, in the second display panel 20, which is a field-sequential display panel, one pixel emits red light, green light, and blue light, so it does not have subpixels. Therefore, the aperture ratio of the pixel of the second display panel 20 is larger than that of the first display panel 10. As a result, the light transmittance of the second display panel 20 is further increased compared to the first display panel 10, so that the image viewed by the observer can be made brighter. Furthermore, for example, if the aperture ratio of the pixel of the second display panel 20 is three times larger than that of the first display panel 10, light passes through the second display panel 20 about three times more easily, and this also has the advantage of improving the image resolution by three times.

[0027] The higher the light transmittance of the second display panel 20, the more preferable. The light transmittance of the second display panel 20 is, for example, preferably in the range of 40% or more and less than 70% and more preferably in the range of 70% or more and less than 80%. Moreover, it is very preferable that the light transmittance of the second display panel 20 is 80% or more.

[0028] The medium layer 30 is disposed between the first display panel 10 and the second display panel 20. A typical example of the material of the medium layer 30 is air, but it may be a gas having a refractive index almost similar to that of air (refractive index 1.0002926), such as argon (refractive index 1.000281), carbon dioxide (refractive index 1.000449), helium (refractive index 1.000036), hydrogen (refractive index 1.000140), nitrogen (refractive index 1.000297), oxygen (refractive index 1.000276), or a mixture of these gases. Furthermore, the medium layer 30 may be a vacuum layer (refractive index 1.0000).

[0029] As shown in FIG. 2, the control unit 50 is electrically connected to the light source 28 and the liquid crystal layer 12a of the first display panel 10. The control unit 50 controls the operations of the light source 28 and the liquid crystal layer 12a. This controls the red, green, and blue light beams emitted from the first display panel 10. The control unit 50 is also electrically connected to the light source 29 and the liquid crystal layer 12b of the second display panel 20. The control unit 50 controls the operations of the light source 29 and the liquid crystal layer 12b. This controls the red, green, and blue light beams emitted from the second display panel 20.

[0030] Next, the path of light rays in the display device 1 of the present invention will be described. The light emitted from the first display panel 10 passes through the medium layer 30 between the first display panel 10 and the second display panel 20 and travels toward the second display panel 20 .

[0031] 3 shows a conventional stacked light field display device 101. The display device 101 includes a first display panel 110 and a second display panel 120. Each of the first display panel 110 and the second display panel 120 is a time-sequential display panel. More specifically, each of the first display panel 110 and the second display panel 120 has substantially the same structure as a known color LCD panel.

[0032] The first display panel 110 includes a light guide plate 26, a diffusion plate 27, a polarizing plate 13a, a glass plate 25a, a liquid crystal layer 12a, a color filter 14a, a glass plate 25b, and a polarizing plate 13b, which are arranged in this order from the rear side. The first display panel 110 includes a backlight 111 as a light source. The second display panel 120 includes a polarizing plate 13c, a glass plate 25c, a liquid crystal layer 12b, a color filter 14b, a glass plate 25d, and a polarizing plate 13d, which are arranged in this order from the rear side. The second display panel 120 does not include a light source.

[0033] In the display device 101, a light ray emitted from the first display panel 110 passes through a subpixel in which a filter of the same color is arranged among the subpixels of the color filter 14a. For example, a green light ray passes through the green subpixel 14G and leaves the first display panel 110. The green light ray emitted from the first display panel 110 passes through the medium layer 30, passes through the green subpixel 14G in which a green filter G is arranged among the subpixels of the color filter 14b of the second display panel 120, enters the viewer's eye, and is visually recognized as green.

[0034] Next, the path of light rays in the display device 1 of this embodiment will be described with reference to Fig. 1. A green light ray emitted from the green sub-pixel 14G of the color filter 14 of the first display panel 10 passes through the medium layer 30 and travels toward a pixel of the second display panel 20. At this time, if a pixel of the second display panel 20 displays a color other than green, it is not possible to control the light rays for each color, and therefore it is not possible to display a correct image.

[0035] In contrast, in the display device 1, the control unit 50 electrically synchronizes the emission of light beams of each color in each of the stacked display panels 10 and 20. In this embodiment, the control unit 50 synchronizes the emission of light beams of each color by performing display for the color of each display panel 10 and 20 or emission of the corresponding light source color at the same timing. As a result, for example, display or emission corresponding to red is driven simultaneously in each of the display panels 10 and 20, so that an image corresponding to red is displayed correctly. Also, at another timing, for example, display or emission corresponding to green is driven simultaneously in each of the display panels 10 and 20, so that an image corresponding to green is displayed correctly. Similarly, an image corresponding to blue is also displayed correctly. The control unit 50 generates a correct group of light beams for each of the colors red, green, and blue by switching the display of these images of each color at high speed while synchronizing them, thereby generating a correct image. As a result, the observer can view a correct stereoscopic image.

[0036] Furthermore, since the display device 1 includes the second display panel 20, which is a field sequential display panel, there is no need to spatially separate the colors red, green, and blue by sub-pixels as in a time sequential display panel, so that the display device 1 can improve the resolution of the image it displays.

[0037] In the display device 1 of this embodiment, the first display panel 10 is a time-sequential display panel and the second display panel 20 is a field-sequential display panel. However, as in a display device 201 of a second embodiment of the present invention shown in FIG. 4, each of the stacked display panels 210, 220 may be a display panel driven by field-sequential control.

[0038] Each of the first display panel 210 and the second display panel 220 includes a glass plate 25, a liquid crystal layer 12, and a glass plate 25 arranged in this order from the rear side. The first display panel 210 includes a light source 28 that emits light of three or more colors including red, green, and blue. The second display panel 220 includes a light source 29 that emits light of three or more colors including red, green, and blue.

[0039] In the display device 201, the control unit 50 preferably drives the light sources 28, 29 of each color of the display panels 210, 220 to blink in electrical synchronization. In other words, it is preferable that each of the multiple display panels 210, 220 is driven to blink in synchronization with each other. This allows correct light beams to be generated for each color of red, green, and blue, so that a correct image can be generated. Therefore, the observer can view a correct stereoscopic image.

[0040] Moreover, in the display device 201, the first display panel 210 and the second display panel 220 do not have optical members such as a color filter and a polarizing plate. This allows the first display panel 210 and the second display panel 220 to be transparent display panels. Therefore, in the display device 201, since each of the display panels 210 and 220 is a field sequential type display panel with high light transmittance, the light transmittance can be increased. Therefore, the image viewed by the observer can be more suitably brightened. Furthermore, as described above, in the display device 201, since the light transmittance of each of the display panels 210 and 220 can be increased, the display device 201 can be a see-through type display device in which the observer can view the back side through the display device 201. Therefore, entertainment different from that of conventional non-see-through type display devices can be provided.

[0041] Further, as in the display device 301 of the third embodiment of the present invention shown in FIG. 5, only the first display panel 310 disposed farthest from the viewer may have the light source 28. In the display device 301 of this embodiment, only the first display panel 310 has the light source 28. In each of the first display panel 310 and the second display panel 320, the glass plate 25, the liquid crystal layer 12, and the glass plate 25 are arranged in this order from the rear side. In the display device 301, the light beam emitted from the first display panel 310 is used to illuminate the other display panel than the first display panel 310, that is, the second display panel 320. Thus, according to this embodiment, in the display device 301, the display panel 320 other than the first display panel 310 does not have a light source, so that the display device 301 can be made smaller and lighter. Also, as described above, in the display device 301, the second display panel 320 does not have a light source, so that the number of light sources that the display device 301 has can be reduced, and noise light can be reduced. This makes it possible to improve the contrast and color of the image, and therefore the quality of the image can be improved more suitably. When each display panel has light sources 28 and 29, as in the display device 1 and the display device 201, the light rays are controlled by the sum of the brightness of each display panel. Therefore, it is easy to make the image brighter, and the quality of the image can be improved more suitably.

[0042] The light beams generated by the display devices 1, 201, and 301 of the present embodiment pass through the multiple display panels, and finally enter the viewer's eyes and are imaged on the retina. This allows the viewer to view the image. Also, the person views the display pattern on the display panel that exists within the field of view (inside the viewing angle) that diverges spherically from the viewpoint. Therefore, among the multiple display panels, the display panel that is arranged farther from the viewer requires a larger area. In other words, if the areas of the multiple stacked display panels are made the same, the display of the outer part of the display panel is wasted as the display panel is arranged closer to the viewer. Therefore, part of the calculation process of the light field control performed by the control unit 50 is wasted, and the calculation cost increases more than necessary. From the above, it is preferable that the area of ​​the first display panel arranged farthest from the viewer is the largest among the areas of the multiple display panels. Although not shown in the figures, in this embodiment, the area of ​​the first display panel is the largest among the areas of the multiple display panels. Therefore, according to this embodiment, the calculation process of the light field control performed by the control unit 50 for the pixels arranged in the outer part of the second display panel can be reduced, and the calculation cost can be reduced. It is more preferable that the display panel arranged closer to the front among the multiple display panels has a smaller area. With this configuration, the calculation process of the light field control performed by the control unit 50 for the pixels arranged in the outer part of each display panel can be reduced, and the calculation cost can be further reduced. It is to be noted that in this embodiment, the area of ​​the display panel refers to the area of ​​the part of the outer surface of the display panel facing the front side where an image is displayed.

[0043] Each of the display devices 1, 201, 301 of the present invention can be configured as a head mounted display device (hereinafter referred to as an HMD device) in which an eyepiece (not shown) is arranged on the front side of the second display panel 20, 220, 320. That is, the HMD device includes the display device 1, 201, 301 and the eyepiece. In the HMD device, the observer can observe the display device 1, 201, 301 through the eyepiece. Therefore, according to this embodiment, the observer can observe the image formed by the display device 1, 201, 301 through the eyepiece. In the HMD device, the position of the observer's viewpoint can be fixed, so that the number of light beam groups generated can be reduced. Therefore, the load of the calculation process performed by the control unit 50 to form the light beams can be reduced. Therefore, the reproduction accuracy of the light beam groups can be further improved, so that the quality of the image can be more suitably improved.

[0044] Although not shown, in this embodiment, each display panel is a regular polygon having four or more corners. The front view shape of each display panel is not particularly limited, and may be a regular hexagon having six corners or a regular nonagon having nine corners. In general, the eyepiece lens used in the HMD device is circular and often has the same viewing angle in any direction. As described above, a person views a circular image on the display panel within the viewing angle from the viewpoint, so the closer the shape of the display panel is to a circular shape, the more favorably the quality of the image viewed by the observer can be improved. However, it is often difficult to manufacture a circular display panel. Therefore, the shape of the display panel is preferably a polygon, and more preferably a regular polygon. According to this embodiment, as described above, each display panel is a regular polygon having four or more corners. Therefore, in the HMD device, the quality of the image viewed by the observer can be more favorably improved, and the manufacturing man-hours and manufacturing costs of each display panel can be suppressed from increasing.

[0045] As described above, according to the present embodiment, the first display panels 210 and 310 of the display devices 201 and 301 are transparent. Therefore, in the HMD device including the display devices 201 and 301, the light transmittance of all the display panels can be increased, so that a see-through type HMD device can be configured. In the see-through type HMD device, the observer can view the scene on the rear side through the HMD device, so that an MR (Mixed Reality) type HMD device can be configured in which the image displayed by the HMD device and the scene on the rear side of the HMD device can be viewed in a superimposed manner. Note that, when the first display panel 10 is a non-transparent display panel like the display device 1, a VR (Virtual Reality) type HMD device can be configured.

[0046] As described above, the second display panel 20, 220, 320, which is a field sequential display panel, does not have optical members such as a polarizing plate and a color filter. In the second display panel 20, 220, 320, instead of these optical members, the light is diffused and controlled by the liquid crystal arranged in the pixel region, so that the light is emitted from the second display panel 20, 220, 320 to the front side. According to this embodiment, the second display panel 20, 220, 320 is a light diffusion type liquid crystal display panel. Therefore, in a display device in which field sequential display panels are stacked, such as the display device 201, 301, the sum of diffused light from the multiple display panels is incident on the observer's eye, so that the brightness of the image displayed by the display device 201, 301 can be more suitably increased. This makes it possible to more suitably increase the quality of the image.

[0047] As described above, the display devices 1, 201, and 301 according to the present embodiment can provide images with higher brightness and resolution than the conventional stacked light field type display device 101. This contributes to improving the quality of images.

[0048] In this embodiment, in order to simplify the description of the display device, the number of display panels provided in the display device is two, but this is merely one aspect of the present invention, and the display device may have three or more display panels. For example, in the case of a three-layer stacked light field display device having three display panels, in addition to the first and second display panels, a third display panel may be disposed on the most front side. In this configuration, by making each of the first, second, and third display panels a field sequential display panel having high light transmittance, it is possible to provide a display device that can display images with improved stereoscopic vision and high brightness and high resolution, as compared with a two-layer stacked light field display device.

[0049] Furthermore, in the display devices 1, 201, and 301 according to the present embodiment, at least one display panel is a field sequential display panel with high light transmittance, so that the brightness and resolution of images can be improved compared to the conventional display device 101. Therefore, a display device that contributes to more suitably improving image quality can be provided.

[0050] The display device according to the present invention will be further described using examples and comparative examples. Note that the technical scope of the present invention is not limited solely by the specific contents of the examples.

[0051] Example 1 The display device 1 of the first embodiment corresponds to the display device 1 of the first embodiment described above. First, the display device 1 for one eye will be described. As shown in FIG. 1, the first display panel 10 is a color LCD panel. The first display panel 10 has three light sources 28, namely, a red light source, a green light source, and a blue light source, and includes a light guide plate 26 and a diffusion plate 27 that emit light emitted by the light sources 28 to the red sub-pixel 14R, the green sub-pixel 14G, and the blue sub-pixel 14B. The second display panel 20 is a transparent field sequential display panel and has three light sources 29, namely, a red light source, a green light source, and a blue light source. The first display panel 10 and the second display panel 20 are in a regular nonagonal shape when viewed from the front. The two display panels 10 and 20 are stacked with a gap of 7 mm between them so that their centers of gravity are completely aligned when viewed from the front. The material of the medium layer 30 is air. As described above, the area of ​​the first display panel 10 is made larger than the area of ​​the second display panel 20 to match the viewing angle of the human eye.

[0052] The control unit 50 electrically synchronizes the light emission of the light source 28 in the first display panel 10 and the light emission of the light source 29 in the second display panel 20 for each color. Specifically, the control unit 50 causes all the pixels of the second display panel 20 to emit green light at the same time that all the pixels of the first display panel 10 emit green light. As a result, the green light emitted from the first display panel 10 and the green light emitted from the second display panel 20 are simultaneously incident on the viewer's eyes.

[0053] The luminance of each color of light emitted from the first display panel 10 is set to 200 [cd / m 2 ], and the luminance of each color of light emitted from the second display panel 20 is set to 50 [cd / m 2 ], and the light transmittance of the second display panel 20 was set to 80[%].

[0054] Two display devices 1 for one eye were fabricated, one for the right eye and the other for the left eye. An eyepiece (not shown) was attached to the front side of the display device 1 according to Example 1 to fabricate the HMD device according to Example 1.

[0055] The luminance of the display device 1 was measured by a color luminance meter (Multimedia Display Tester 3298F manufactured by Yokogawa Electric Corporation) using the HMD device. Furthermore, the quality of the image of the display device 1 was evaluated visually using the HMD device.

[0056] The theoretical brightness of the display device 1 of the first embodiment is calculated as follows. First, the brightness of the light emitted from the first display panel 10 after passing through the second display panel 20 is 160 [cd / m 2 As described above, the luminance of the light emitted from the second display panel 20 is 50 [cd / m 2 Therefore, the estimated luminance of the light emitted by the display device 1 is 210 [cd / m 2 The average brightness of the light emitted from the HMD device of Example 1 measured 10 times was about 206.32 [cd / m 2 ], which is almost the same brightness as the estimated value mentioned above.

[0057] Furthermore, the quality of the image displayed by the HMD device according to Example 1 was good. The HMD device according to Example 1 can be used as a VR type HMD device.

[0058] Example 2 The display device 201 of the second embodiment corresponds to the display device 201 of the second embodiment described above. First, the display device 201 for one eye will be described. As shown in FIG. 4, each of the first display panel 210 and the second display panel 220 is a display panel that is transparent and driven by field sequential control. The first display panel 210 has three color light sources 28, which are a red light source, a green light source, and a blue light source. The second display panel 220 has three color light sources 29, which are a red light source, a green light source, and a blue light source. The shape of each of the first display panel 210 and the second display panel 220 when viewed from the front is a regular octagon. The two display panels 210 and 220 are stacked with a gap of 7 mm between them so that their centers of gravity are completely aligned when viewed from the front. The material of the medium layer 30 is air. The area of ​​the first display panel 210 is made larger than the area of ​​the second display panel 220 to match the viewing angle of the human eye.

[0059] The control unit 50 electrically synchronizes the light emission of the light source 28 in the first display panel 210 and the light emission of the light source 29 in the second display panel 220 for each color. Specifically, the control unit 50 causes all the pixels of the second display panel 220 to emit green light at the same time that all the pixels of the first display panel 210 emit green light. As a result, the green light emitted from the first display panel 210 and the green light emitted from the second display panel 220 enter the viewer's eyes at the same time.

[0060] The luminance of light emitted from each of the display panels 210 and 220 is set to 100 [cd / m 2 ], and the light transmittance of each of the display panels 210 and 220 was set to 90[%].

[0061] Two display devices 201 for one eye were fabricated, one for the right eye and the other for the left eye. An eyepiece (not shown) was attached to the front side of the display device 201 to fabricate an HMD device according to Example 2.

[0062] The luminance and image quality of the display device 201 according to the second embodiment were evaluated in the same manner as in the evaluation of the luminance and image quality of the display device 1 according to the first embodiment described above.

[0063] The theoretical brightness of the display device 201 of the second embodiment is calculated as follows. First, the brightness of the light emitted from the first display panel 210 after passing through the second display panel 220 is 90 [cd / m 2 As described above, the luminance of the light emitted from the second display panel 220 is 100 [cd / m 2 Therefore, the estimated luminance of the light emitted by the display device 201 is 190 [cd / m 2 The average brightness of the light emitted from the HMD device of Example 2 measured 10 times was about 187.32 [cd / m 2 ], which is almost the same brightness as the estimated value mentioned above.

[0064] Furthermore, the quality of the image displayed by the HMD device according to Example 2 was good. The HMD device according to Example 2 can be used as an MR type HMD device.

[0065] Example 3 The display device 301 of the third embodiment corresponds to the display device 301 of the third embodiment described above. First, the display device 301 for one eye will be described. As shown in FIG. 5, the first display panel 310 is a display panel that is transparent and driven by field sequential control. The first display panel 310 has three light sources 28 of red, green, and blue colors. The second display panel 320 is a display panel that is transparent and driven by field sequential control. The second display panel 320 has a structure in which the light sources 28 are removed from the first display panel 310. The pixels of the second display panel 320 are illuminated by the light emitted from the light sources 28 of the first display panel 310. The shapes of the first display panel 310 and the second display panel 320 when viewed from the front are regular hexagonal shapes. The two display panels 310 and 320 are stacked with a gap of 7 mm between them so that their centers of gravity are completely aligned when viewed from the front. The material of the medium layer 30 is air. The area of ​​the first display panel 310 is made larger than the area of ​​the second display panel 320 to match the viewing angle of the human eye.

[0066] The luminance of the light emitted from the first display panel 310 is set to 200 [cd / m 2 ], and the light transmittance of each of the display panels 210 and 220 was set to 90[%].

[0067] Two display devices 301 for one eye were fabricated, one for the right eye and the other for the left eye. An eyepiece (not shown) was attached to the front side of the display device 301 according to Example 3 to fabricate the HMD device according to Example 3.

[0068] The luminance and image quality of the display device 301 according to the third embodiment were evaluated in the same manner as in the evaluation of the luminance and image quality of the display device 1 according to the first embodiment described above.

[0069] The theoretical brightness of the display device 301 of the third embodiment is calculated as follows: The brightness of the light emitted from the first display panel 310 after passing through the second display panel 320 is 180 [cd / m 2The average brightness of the light emitted from the HMD device of Example 2 measured 10 times was about 181.32 [cd / m 2 ], which is almost the same brightness as the estimated value mentioned above.

[0070] Furthermore, the quality of the image displayed by the HMD device according to Example 3 was good. The HMD device according to Example 3 can be used as an MR type HMD device.

[0071] (Comparative Example) The display device 101 of the comparative example corresponds to the conventional display device 101 described above. First, the fabrication of the display device 101 for one eye will be described. As shown in FIG. 3, each of the first display panel 110 and the second display panel 120 is a color LCD panel. The first display panel 110 has optical members such as a color filter 14a and polarizing plates 13a and 13b. The second display panel 120 has optical members such as a color filter 14b and polarizing plates 13c and 13d. The first display panel 110 has a backlight 111, and the second display panel 120 does not have a light source such as a backlight. The first display panel 110 and the second display panel 120 are regular nonagonal shapes when viewed from the front. The two display panels 110 and 120 are stacked with a gap of 7 mm between them so that their centers of gravity are completely aligned when viewed from the front. The material of the medium layer 30 is air. The area of ​​the first display panel 110 is made larger than the area of ​​the second display panel 120 to match the viewing angle of the human eye.

[0072] The luminance of each color of light emitted from the first display panel 110 is set to 600 [cd / m 2 ], and the light transmittance of the second display panel 120 was set to 16.7[%].

[0073] Two display devices 101 for one eye were produced, one for the right eye and the other for the left eye. An eyepiece (not shown) was attached to the front side of the display device 101 according to the comparative example to produce an HMD device according to the comparative example.

[0074] The luminance and image quality of the display device 201 according to the comparative example were evaluated in the same manner as in the evaluation of the luminance and image quality of the display device 1 according to the first embodiment described above.

[0075] The theoretical luminance of the display device 101 of the comparative example is calculated as follows: The luminance of the light emitted from the first display panel 110 after passing through the second display panel 120 is 100 [cd / m 2 The average brightness of the light emitted from the HMD device of the comparative example measured 10 times was about 98.32 [cd / m 2 ], which is almost the same brightness as the estimated value mentioned above.

[0076] In the display device 101 of the comparative example, in order to make the luminance of the light emitted from the display device 101 equivalent to the luminance of the light emitted from the display device 1 of the embodiment 1, the output of the backlight 111 is increased and the luminance of the light emitted by the backlight 111 is increased to 7500 [cd / m 2 ]. In this case, the amount of heat generated by the backlight 111 increases, causing the temperature of the backlight 111 to rise. For this reason, it is necessary to take measures against heat, such as providing a heat insulating member that suppresses the transfer of heat from the backlight 111 to the components constituting the display device 101, such as the light guide plate 26 and the diffusion plate 27, using materials for the components constituting the display device 101 that have high heat resistance, or cooling using an air conditioner or a cooling water circulator. Therefore, with the conventional display device 101, there is a concern that these heat countermeasures will increase the manufacturing cost.

[0077] According to this embodiment, the multiple display panels include at least one second display panel 20, 120, 220 that is transparent and driven by field sequential control. Therefore, the light transmittance of the second display panel 20, 120, 220 can be increased compared to when the second display panel 20, 120, 220 is a color LCD panel driven by time sequential control. This makes it possible to suppress an increase in the output of the light source 28, and therefore to suppress an increase in the amount of heat generated by the light source 28. This reduces the need to take the above-mentioned heat countermeasures. Therefore, it is possible to suppress an increase in the manufacturing cost of the display device 1, 201, 301.

[0078] Furthermore, the quality of the display image of the HMD device according to the comparative example was inferior to the quality of the images of the HMD devices of Examples 1 to 3. Therefore, according to this embodiment, the quality of the image can be improved compared to the conventional display device 101.

[0079] Although the embodiment and examples of the present invention have been described above, the specific configuration is not limited to this embodiment, and configuration changes and combinations within the scope that does not depart from the gist of the present invention are also included. [Explanation of symbols]

[0080] 1, 201, 301 Display device 10, 210, 310 First display panel 20, 220, 320 Second display panel 28 light source 30 Medium Layer

Claims

1. A laminated light field display device in which a plurality of display panels are laminated with a medium layer therebetween, The plurality of display panels include a first display panel disposed furthest from a viewer; At least one second display panel other than the first display panel, the second display panel being transparent and driven by a field sequential control; A display device comprising:

2. the first display panel is driven by a time sequential control and has a light source that emits light of three or more colors including red, blue, and green; The display device according to claim 1 , wherein the light source is driven to blink in synchronization with the second display panel.

3. 2. The display device according to claim 1, wherein each of the plurality of display panels is driven by a field sequential control and is driven to blink in synchronization with one another.

4. The display device according to claim 1 , wherein the first display panel has a largest area among the areas of the plurality of display panels.

5. 4. A display device according to claim 1, characterized in that only the first display panel is provided with a light source.

6. 4. The display device according to claim 1, wherein the second display panel is a light-diffusing liquid crystal display panel.

7. A display device according to any one of claims 1 to 3 and an eyepiece lens, A head mounted display device, characterized in that the display device can be observed through the eyepiece.

8. The head mounted display device according to claim 7 , wherein at least one of the display panels is in the shape of a regular polygon having four or more corners.

9. The head mounted display device according to claim 7 , wherein the first display panel is transparent.

Images