Display device and head-up display device

Abstract

The present invention provides a display device and a head-up display device that can more effectively enhance image contrast to match the shape of the displayed image. [Solution] The display device comprises an illumination device that emits illumination light, a liquid crystal display panel having an image display area 18b for displaying an image and a non-display area 18c for not displaying an image, and emitting display light in response to the illumination light, and a monochrome liquid crystal panel 12 located between the illumination device and the liquid crystal display panel, with the area corresponding to the non-display area 18c in a black display state Sb and the area corresponding to the image display area 18b in a white display state Sw.

Description

Technical Field

[0001] The present disclosure relates to a display device and a head-up display device.

Background Art

[0002] In the head-up display device described in Patent Document 1, a display unit that displays a display image including a first display image, a second display image, and a third display image, and a backlight that illuminates each of the first display image, the second display image, and the third display image in a separate illumination area are provided.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1 above, since the illumination area (dimming zone) is large with respect to the pixel size of each display image, halation may occur at the outer peripheral portion of each display image, and the image contrast may decrease. Here, in order to match the dimming zone to the pixel size, it is necessary to make the arrangement pitch of LEDs (Light Emitting Diodes) finer, but the finer the arrangement pitch, the lower the light utilization efficiency, which is the efficiency of the luminance of the dimming zone with respect to the power consumption of the LED. As described above, it has been difficult to increase the image contrast while matching the dimming zone to the pixel size of each display image from the viewpoint of light utilization efficiency.

[0005] The present disclosure has been made in view of the above actual situation, and an object thereof is to provide a display device and a head-up display device that can more preferably increase the image contrast in accordance with the shape of the display image. [Means for solving the problem]

[0006] To achieve the above objectives, the display device relating to the first aspect of this disclosure is: A lighting device that emits illumination light, A display panel having an image display area for displaying an image and a non-display area for not displaying an image, and which emits display light upon receiving the illumination light, The system includes a light-transmitting / light-shielding switching panel located between the lighting device and the display panel, which sets the area corresponding to the non-display area to a light-shielding state and the area corresponding to the image display area to a light-transmitting state.

[0007] To achieve the above objectives, the head-up display device relating to the second aspect of this disclosure is: By projecting the display light emitted by the display device onto the projection target, an enlarged projected image of the display panel is displayed. [Effects of the Invention]

[0008] According to this disclosure, the image contrast can be more preferably enhanced to match the shape of the displayed image. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of a head-up display device with a cross optical system according to the first embodiment of this disclosure. [Figure 2] This is a schematic cross-sectional view of a display device as seen from the side according to the first embodiment of this disclosure. [Figure 3] The upper part of the first embodiment of this disclosure is a schematic diagram showing the image display area on the display surface, and the lower part is a schematic diagram showing the light source and dimming zone. [Figure 4] This is a schematic cross-sectional view of a head-up display device with a non-cross optical system according to a modified example of the present disclosure. [Figure 5] This is a schematic cross-sectional view of a modified display device as seen from the side. [Figure 6]It is a schematic front view showing a liquid crystal display panel according to the first embodiment of the present disclosure. [Figure 7] It is a schematic front view showing a light source and a dimming zone according to the first embodiment of the present disclosure. [Figure 8] It is a schematic front view showing a monochrome liquid crystal panel according to the first embodiment of the present disclosure. [Figure 9] It is a schematic cross-sectional view of a display device viewed from the lateral direction according to a comparative example. [Figure 10] It is a schematic front view showing a monochrome liquid crystal panel according to a comparative example. [Figure 11] It is a schematic front view showing a liquid crystal display panel according to the first embodiment of the present disclosure. [Figure 12] It is a schematic cross-sectional view of a liquid crystal display panel, a monochrome liquid crystal panel, and a diffusion plate viewed from the lateral direction according to the second embodiment of the present disclosure. [Figure 13] It is an enlarged schematic cross-sectional view of a liquid crystal display panel, a monochrome liquid crystal panel, and a diffusion plate viewed from the lateral direction according to the second embodiment of the present disclosure. [Figure 14] It is an enlarged schematic cross-sectional view of a liquid crystal display panel, a monochrome liquid crystal panel, and a diffusion plate viewed from the lateral direction according to a modified example of the present disclosure. [Figure 15] It is a schematic cross-sectional view of a liquid crystal display panel, a monochrome liquid crystal panel, and a diffusion plate viewed from the lateral direction according to a modified example of the present disclosure. [Figure 16] It is a schematic view of a liquid crystal display panel and a monochrome liquid crystal panel viewed from the direction of parallel light propagation according to a modified example of the present disclosure.

Embodiments for Carrying Out the Invention

[0010] (First Embodiment) The display device and the head-up display device according to the first embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the head-up display device 100 is installed, for example, in the dashboard of the vehicle 200. The head-up display device 100 emits display light L representing an image toward the windshield 201, which is a projection member of the vehicle 200, and displays a virtual image W by the display light L reflected by the windshield 201. The virtual image W is displayed in a rectangular display area that is long in the left-right direction and short in the up-down direction as viewed by the viewer.

[0011] The head-up display device 100 includes a display device 10b, a first mirror 21, a second mirror 22, a control unit 25, and a housing 30.

[0012] The housing 30 is formed in a box shape from a light-shielding resin, metal, or the like, and houses the display device 10b and the mirrors 21 and 22. An opening 30c is formed in the housing 30 at a position facing the windshield 201 in the height direction. The housing 30 includes a window portion 31 formed in a plate shape made of a light-transmitting resin such as acrylic that is fitted into the opening 30c and through which the display light L passes.

[0013] The first mirror 21 and the second mirror 22 constitute a relay optical system that reflects the display light L from the display device 10b and guides it to the windshield 201. The first mirror 21 reflects the display light L emitted from the display device 10b toward the second mirror 22. The first mirror 21 is a correction mirror and is a concave mirror that curves in a concave shape along the height direction of the vehicle and extends linearly along the width direction of the vehicle. The first mirror 21 may curve in a concave shape or a convex shape in the width direction of the vehicle.

[0014] The first mirror 21 reflects the display light L from the display device 10b toward the second mirror 22 such that it intersects at a cross point CP when viewed from the vehicle width direction of the vehicle 200. The cross point CP is located between the first mirror 21 and the second mirror 22 in the optical path of the display light L. The display light L converges from the first mirror 21 to the cross point CP and diverges from the cross point CP toward the second mirror 22. In other words, the display light L is imaged between the first mirror 21 and the second mirror 22 in the height direction.

[0015] The second mirror 22 is a concave mirror that reflects the display light L from the display device 10b toward the windshield 201.

[0016] As shown in Figure 2, the display device 10b comprises a liquid crystal display panel 18 and an illumination device 15 for illuminating the liquid crystal display panel 18. The illumination device 15 comprises a case 14, a substrate 16, a light diffusing member 17, a plurality of light sources 19, and first to third lenses 51 to 53. In the following explanation, the lateral direction H is the direction corresponding to the left-right direction (vehicle width direction) of the virtual image W visible to the viewer, and the vertical direction V is the direction corresponding to the up-down direction of the virtual image W visible to the viewer. The lateral direction H and the vertical direction V are orthogonal to each other, and are also orthogonal to the parallel light propagation direction Z of the illumination light IL, which is parallelized by the third lens 53.

[0017] The case 14 is formed in a rectangular cylindrical shape from a light-shielding resin or metal. The substrate 16 and the first to third lenses 51 to 53 are housed inside the case 14. The liquid crystal display panel 18 is positioned to cover the opening 14a of the case 14.

[0018] The substrate 16 is plate-shaped and extends along the lateral direction H and the vertical direction V. Multiple light sources 19 are mounted on the surface of the substrate 16 facing the third lens 53. Each light source 19 is, for example, an LED. Specifically, the multiple light sources 19 are arranged in a matrix in the vertical direction V and the horizontal direction H.

[0019] The liquid crystal display panel 18 has a display surface 18a that displays an image (intermediate image) by receiving illumination light IL from each light source 19 through first to third lenses 51 to 53. The display surface 18a is located on the surface of the liquid crystal display panel 18 on the side where the display light L is emitted, and has a rectangle that is long in the horizontal direction H and short in the vertical direction V. Display light L showing the image is emitted from the display surface 18a of the liquid crystal display panel 18 toward the second mirror 22. The liquid crystal display panel 18 is a TFT (Thin Film Transistor) type liquid crystal panel.

[0020] The control unit 25 includes a CPU (Central Processing Unit), a GDC (Graphics Display Controller), ROM (Read Only Memory), and RAM (Random Access Memory), etc. The control unit 25 controls the display device 10b, for example, a plurality of light sources 19 and a liquid crystal display panel 18.

[0021] The control unit 25 has a local dimming function that adjusts the brightness for each of the multiple dimming zones 18z, which are partitioned vertically V and horizontally H on the display surface 18a, according to the content of the image displayed on the display surface 18a, as shown in the lower part of Figure 3. Each of these is associated with one or more light sources 19 (LEDs). The control unit 25 lights up only the dimming zone 18z on the display surface 18a that corresponds to the image display area 18b (see upper part of Figure 3) on which the content is displayed, and turns off the dimming zones 18z on the display surface 18a other than the image display area 18b. In this embodiment, the control unit 25 had a local dimming function, but it is also possible to have all the light sources 19 turn on or off simultaneously without a local dimming function.

[0022] As shown in Figure 2, the first to third lenses 51 to 53 are arranged in the order of third lens 53, second lens 52, and first lens 51, starting from the lens closest to the light source 19. Illumination light IL from the light source 19 is transmitted through the third lens 53, second lens 52, and first lens 51 in the order of their thickness. The first to third lenses 51 to 53 are each formed from transparent optical resin or optical glass and have a rectangular plate shape that is long in the lateral direction H and short in the vertical direction V.

[0023] The third lens 53 parallelizes the light emitted from the light source 19 to the parallel light propagation direction Z. The third lens 53 comprises a plurality of convex lens portions 53a. The plurality of convex lens portions 53a are arranged in a matrix so as to correspond one-to-one with the light source 19 described above. For example, the convex lens portion 53a forms a square when viewed from the parallel light propagation direction Z, and the length of one side of this square is set to 6 mm or less, for example, 5.6 mm. The third lens 53 is not limited to a lens; it may also be a reflector, as long as it is a collimating means.

[0024] The first lens 51, the second lens 52, and the liquid crystal display panel 18 are arranged parallel to each other and tilted in a direction that is not perpendicular to the parallel light propagation direction Z when viewed from the lateral direction H. The light diffusing member 17 is a diffuser plate that diffuses the illumination light IL from the first lens 51 and emits it to the liquid crystal display panel 18. The light diffusing member 17 can be any optical material that has the function of diffusing light, for example, its surface may be made up of bead material or a fine uneven structure, or it may be made up of a dot sheet or a translucent milky white sheet. The first lens 51 and the second lens 52 are provided to distribute the illumination light IL to the display surface 18a and, furthermore, to the viewer's eye box.

[0025] In particular, in this embodiment, the dimming zone is made substantially finer by using a monochrome liquid crystal panel.

[0026] As shown in Figure 6, the illumination device 15 of the display device 10b includes, in addition to the case 14, substrate 16, light diffusion member 17, multiple light sources 19, and first to third lenses 51 to 53 described above, a monochrome liquid crystal panel 12 provided between the light diffusion member 17 and the first lens 51.

[0027] The monochrome liquid crystal panel 12 is a segment-type LCD (Liquid Crystal Display). The monochrome liquid crystal panel 12 has a shutter function that blocks a portion of the illumination light IL from the first lens 51 so as to surround the image display area 18b (see Figure 6) of the liquid crystal display panel 18 when viewed from the parallel light propagation direction Z. By blocking a portion of the dimming zone 18z (see Figure 7) with the monochrome liquid crystal panel 12, it becomes possible to make the dimming zone 18z substantially finer to match the outline of the image display area 18b.

[0028] As shown in Figure 8, the monochrome liquid crystal panel 12 has a plurality of pixels 12a arranged in a matrix in the vertical direction V and the horizontal direction H. Each pixel 12a is square. The pitch Pg of the pixels 12a is smaller than the pitch Pr of the convex lens portion 53a. The pitch Pr of the convex lens portion 53a is the same as the pitch of the light source 19. Under the control of the control unit 25, the monochrome liquid crystal panel 12 switches the light transmittance of each pixel 12a between 100% and 0%. When the light transmittance of each pixel 12a is 100%, it is in a white display state Sw where light can pass through, and when the light transmittance is 0%, it is in a black display state Sb where light is blocked.

[0029] As shown in Figure 7, each dimming zone 18z is sized to include multiple pixels 12a when viewed from the parallel light propagation direction Z. One dimming zone 18z corresponds to a total of nine pixels 12a in a 3x3 grid. Each dimming zone 18z forms a square, for example, with a length of 10-12 mm in both width and height. In order to make the dimming zones 18z effectively smaller to match the outline of the image display area 18b, some of the multiple pixels 12a corresponding to the illuminated dimming zone 18z are set to a black display state Sb, and the rest to a white display state Sw. In this example, one dimming zone 18z corresponded to a total of 9 pixels 12a (3 horizontally x 3 vertically), but this is not limited to this. For example, it could correspond to a total of 4 pixels 12a (2 horizontally x 2 vertically), a total of 16 pixels (4 horizontally x 4 vertically), a total of 25 pixels (5 horizontally x 5 vertically), or a total of 36 pixels 12a (6 horizontally x 6 vertically).

[0030] In one example of this embodiment, the multiple light sources 19 (multiple dimming zones 18z) and the multiple convex lens units 53a are arranged in a 5x2 configuration, for a total of 10 units. However, the number of dimming zones 18z and multiple convex lens units 53a is not limited to 10 units; for example, there may be 4 units in a 2x2 configuration, or 9 units in a 3x3 configuration.

[0031] As shown in Figure 8, the multiple pixels 12a are arranged in a 15x6 grid, for a total of 90 pixels. However, the number of multiple pixels 12a is not limited to 90; for example, there could be a 16x8 grid, for a total of 128 pixels. In this embodiment, the first and second lenses 51 and 52 can be any of the lenses disclosed in the first embodiment. For example, the first lens 51 is a Fresnel lens, and the second lens 52 is a lenticular lens.

[0032] As shown in Figure 6, the display surface 18a of the liquid crystal display panel 18 has an image display area 18b for displaying an image and a non-display area 18c that serves as the background and does not display an image. Depending on the content displayed on the display surface 18a, the position, size, or shape of the image display area 18b and the non-display area 18c changes. The image display area 18b may have a shape in which a part of the dimming zone 18z is missing when viewed from the parallel light propagation direction Z.

[0033] The operation of the display device 10b when an image display area 18b and a non-display area 18c are set on the display surface 18a in the manner shown in Figure 6 will be explained. In this case, as shown in Figure 7, a portion of the dimming zones 18z, specifically the illuminated area 18L, is illuminated, while the remaining dimming zones 18z, specifically the unlit area 18F, are unlit. The entire unlit area 18F overlaps with the non-display area 18c. A portion of the illuminated area 18L, Ph, overlaps with the non-display area 18c, while the remaining portion of the illuminated area 18L overlaps with the image display area 18b.

[0034] As shown in Figure 8, among the multiple pixels 12a of the monochrome liquid crystal panel 12, the area corresponding to the non-display area 18c is in a black display state Sb, and the area corresponding to the image display area 18b is in a white display state Sw. That is, the black display state Sb is formed in the area that overlaps with the off area 18F and a part Ph (see Figure 6) of the illuminated area 18L where the non-display area 18c overlaps. As a result, the monochrome liquid crystal panel 12 can shield the illumination light IL from the illuminated area 18L to match the outline of the image display area 18b. Therefore, halation at the outer edge of the image display area 18b is suppressed. Thus, the image contrast of the display surface 18a can be increased, and the display quality of the image can be improved.

[0035] The display device 10c shown in Figures 9 and 10, relating to the comparative example, does not have a monochrome liquid crystal panel 12. Therefore, in this comparative example, in order to suppress the occurrence of halation at the outer edge of the image display area, as in this embodiment, the same number of light sources 19 and convex lens portions 53a as the number of pixels in the monochrome liquid crystal panel 12 are required. Thus, in this comparative example, it is necessary to narrow the spacing between the light sources 19 and make the pitch Pr of each of the convex lens portions 53a and light sources 19 finer. The pitch Pr in Figure 10 relating to the comparative example is finer than the pitch Pr in Figure 7 according to this embodiment. For example, while the pitch Pr in Figure 7 according to this embodiment is 10 to 12 mm, the pitch Pr in Figure 10 relating to the comparative example is about 5 mm. Here, it is known that the finer the pitch Pr, the lower the light utilization efficiency, which is the efficiency of the brightness of the dimming zone 18z relative to the power consumption of the light source 19. On the other hand, increasing the pitch Pr does not reduce the light utilization efficiency, but it causes halation at the outer edge of the image display area and reduces the image contrast. As described above, it was difficult to increase the light utilization efficiency while increasing the image contrast.

[0036] This embodiment has been made in view of the above circumstances, and aims to provide a display device and a head-up display device that can more preferably enhance image contrast according to the shape of the displayed image.

[0037] In order to achieve the above objectives, this embodiment discloses, for example, the technical ideas described in (1) to (3) below. (1) The display device 10b comprises an illumination device 15 that emits illumination light IL, a liquid crystal display panel 18 which is an example of a display panel having an image display area 18b for displaying an image and a non-display area 18c for not displaying an image, and which emits display light L in response to the illumination light IL, and a monochrome liquid crystal panel 12 which is an example of a light-transmitting / light-shielding switching panel located between the illumination device 15 and the liquid crystal display panel 18, and which sets the area corresponding to the non-display area 18c to a light-shielding state (e.g., black display state Sb) and the area corresponding to the image display area 18b to a light-transmitting state (e.g., white display state Sw). With this configuration, the monochrome liquid crystal panel 12 can enhance image contrast to better match the shape of the displayed image, even if the illumination device 15 does not have a local dimming function.

[0038] (2) The lighting device 15 has a local dimming function that adjusts the brightness for each of the multiple dimming zones 18z. With this configuration, image contrast is improved not only by the action of the monochrome liquid crystal panel 12, but also by the difference in brightness of each light source 19. Furthermore, with this configuration, by using a monochrome liquid crystal panel 12, it is not necessary to increase the number of light sources 19 and convex lens units 53a while increasing image contrast, thus suppressing a decrease in light utilization efficiency. In addition, by suppressing a decrease in light utilization efficiency, power saving of the display device 10b can be achieved.

[0039] (3) The monochrome liquid crystal panel 12 has multiple pixels 12a that are smaller in size than the multiple dimming zones 18z and are arranged in a matrix. The monochrome liquid crystal panel 12 is configured to allow switching between a light-shielding state (black display state Sb) and a light-transmitting state (white display state Sw) for each of the multiple pixels 12a. This configuration allows the use of a general-purpose monochrome liquid crystal panel 12.

[0040] (4) The head-up display device 100 displays an enlarged projected image (virtual image W) of the display image of the liquid crystal display panel 18 by projecting the display light L emitted by the display device 10b onto the windshield 201, which is the projection target. In this configuration, the display image on the liquid crystal display panel 18 of the head-up display device 100 is a reduced virtual image W, so the pitch Pr of the light source 19 and the convex lens section 53a tends to be fine, and the light utilization efficiency tends to decrease. For this reason, using a monochrome liquid crystal panel 12 to increase image contrast while maintaining a large pitch Pr of the light source 19 and the convex lens section 53a is beneficial in the head-up display device 100 compared to a direct-view television or monitor.

[0041] (Second Embodiment) A display device and a head-up display device according to the second embodiment of this disclosure will be described with reference to the drawings. This embodiment differs from the first embodiment in that the brightness efficiency is improved by shifting the image display area 18b and the white display state Sw by a predetermined offset amount G. The differences from the first embodiment will be described below.

[0042] As shown in Figure 12, the display device comprises a monochrome liquid crystal panel 12, a light diffusing member 17, and a liquid crystal display panel 18.

[0043] The monochrome liquid crystal panel 12 is a monochrome liquid crystal panel and forms a bezel 12v surrounding the outer edge of the panel portion. The panel portion consists of a non-pixel portion 12e located on the outside and a plurality of pixels 12a (so-called active area) located inside and arranged in a matrix in the vertical direction V and horizontal direction H. The pixels 12a switch between a white display state Sw and a black display state Sb depending on the range of the image display area 18b and the non-display area 18c. Both the panel portion and the pixels 12a are rectangular plate-shaped.

[0044] The liquid crystal display panel 18 is a full-color TFT and forms a bezel 18v surrounding the outer edge of the panel portion. The panel portion consists of a non-pixel portion 18e located on the outside and a display surface 18a (so-called active area) located inside it. The display surface 18a is composed of multiple pixels arranged in a matrix in the vertical direction V and the horizontal direction H. The display surface 18a has an image display area 18b and a non-display area 18c. The panel portion and the display surface 18a form a rectangular plate shape.

[0045] The liquid crystal display panel 18 (especially the display surface 18a) is held in a position parallel to the monochrome liquid crystal panel 12 (especially the pixels 12a) and is tilted by an angle θ with respect to the parallel light propagation direction Z. The liquid crystal display panel 18 is tilted such that when the angle θ is decomposed into a vertical V component and a horizontal H component, it has only a vertical V component. For example, the angle θ is 30 degrees. However, the angle θ can be appropriately changed between 1 and 80 degrees. The liquid crystal display panel 18 may also be tilted so that the angle θ has only a horizontal H component, or it may be tilted so that it has both components. This tilt of the liquid crystal display panel 18 suppresses stray light caused by ambient light and realizes a virtual image W that is tilted for easy viewing.

[0046] The image display area 18b is modified as needed within the warping area 18w. For example, the image display area 18b may be modified by changing the displayed content, adjusting the eyebox, or changing the warping parameters due to the rotation of the second mirror.

[0047] In other words, the liquid crystal display panel 18 can physically display within the display surface 18a, but in normal use, it displays images only within the warping area 18w. However, for testing, inspection, adjustment, etc., an image may be temporarily displayed on the display surface 18a outside the warping area 18w. Therefore, even if the pixels 12a are smaller than the display surface 18a, it is sufficient as long as the pixels 12a are mounted in a position that covers at least the area corresponding to the warping area 18w. In this case, the monochrome liquid crystal panel 12 may be held in a position such that the area center of the warping region 18w and the area center of the pixels 12a roughly coincide in a plan view in the parallel light propagation direction Z or in a plan view in the direction normal to the display surface 18a. With this configuration, costs can be reduced by keeping the size of the monochrome liquid crystal panel 12 as small as possible. In another embodiment, the monochrome liquid crystal panel 12 may be held in a position such that, while the pixels 12a cover the warping region 18w in a plan view in the parallel light propagation direction Z, the area center of the warping region 18w and the area center of the pixels 12a are aligned with each other in the vertical direction V. With this configuration, the positioning position of either the horizontal direction H of each panel is made common, so positioning can be performed relatively easily. In another embodiment, the monochrome liquid crystal panel 12 may be held in a position such that, while the pixels 12a cover the warping region 18w in a plan view in the parallel light propagation direction Z, the area center of the warping region 18w and the area center of the pixels 12a are aligned with each other in the horizontal direction H. With this configuration, the positioning position of either the vertical direction V of each panel is shared, so positioning can be performed relatively easily. In another embodiment, the monochrome liquid crystal panel 12 may be held in a position such that, while the pixels 12a cover the warping region 18w in a plan view in the parallel light propagation direction Z, the area center of the display surface 18a and the area center of the pixels 12a generally coincide in a plan view in the parallel light propagation direction Z or in a plan view in the direction normal to the display surface 18a. With this configuration, the center positions of the panels are shared, making positioning easy.

[0048] Here, referring to Figure 13, which is an enlarged view of the key area enclosed by the dashed line in Figure 12, a preferred example of the relative position between the white display state Sw and the image display area 18b will be explained. Among the illumination light IL and display light L, which are composed of multiple luminous beams, the rays closest to the boundary with the non-display area 18c are shown as representative examples.

[0049] Furthermore, in the white display state Sw, the portion of the inclined image display area 18b that corresponds to the end 18be closer to the light source 19 is shifted by an offset amount G in the in-plane direction of the plane formed by the pixels 12a. Specifically, if the point where the normal (dotted line) from the point where the illumination light IL is incident on the image display area 18b reaches pixel 12a is defined as the corresponding point 12p, then the white display state Sw is displayed shifted by an offset amount G from the corresponding point 12p.

[0050] The offset amount G is at least greater than 0 mm. More preferably, it is greater than the length of one pixel constituting pixel 12a.

[0051] From another perspective, the offset amount G is determined based on a*tanθ. Here, the constant a may be the distance from a point between the incident and exit surfaces of the monochrome liquid crystal panel 12 to a point between the incident and exit surfaces of the liquid crystal display panel 18. A typical example of the constant a, shown in the figure, is length a1, which is the distance between the incident surfaces of each panel. Similarly, a typical example, length a2, is the distance between the midpoints in the thickness direction of each panel. Similarly, a typical example, length a3, is the distance between the exit surfaces of each panel. tan represents the tangent. Note that, as shown in the figure, it is most preferable to base the offset on length a1 so that the apertures of the pixels coincide.

[0052] Note that the direction of displacement with offset amount G does not necessarily have to be in the V direction. The direction of displacement should be in the in-plane direction, at least in the direction that brings the light source 19 closer from the corresponding point 12p. If the angle θ has components in both the vertical direction V and the horizontal direction H, it is desirable that the direction of displacement be the direction that brings it closest to the light source 19.

[0053] Even if the liquid crystal display panel 18 is tilted in both the vertical direction V and the horizontal direction H, the direction of the offset may be limited to only one of the vertical direction V or the horizontal direction H. In this case, the θ used to calculate the offset amount G may be calculated using the corresponding components of the angle θ (angle θv, which is the vertical V component of angle θ, or angle θh, which is the horizontal H component of angle θ).

[0054] Most preferably, the white display state Sw corresponds to the image display area 18b in a plan view in the direction of parallel light propagation. However, it may also be displayed with an offset amount that allows for a wider display. In this case, a relatively large amount of illumination light IL reaches the non-display area 18c, resulting in a slight decrease in contrast. Therefore, when the white display state Sw is displayed wider than the image display area 18b by a predetermined overlap amount in the plan view, it is most preferable that this overlap amount be set to less than the length of one pixel 12a. This allows for sufficient illumination of the image display area 18b while minimizing unnecessary illumination of the non-display area 18c.

[0055] This embodiment was made in view of the above circumstances, and aims to provide a display device and a head-up display device that can suitably enhance image contrast according to the shape of the displayed image while improving brightness efficiency.

[0056] This disclosure is not limited to the embodiments and drawings described above. Modifications (including the deletion of components) can be made as appropriate, provided they do not alter the essence of this disclosure. An example of such a modification is described below.

[0057] (modified version) In each of the above embodiments, the head-up display device 100 was configured as a cross optical system in which the display light L reflected by the first mirror 21 does not intersect in the horizontal direction H, but intersects in the vertical direction V at the cross point CP. However, it is not limited to this cross optical system and may be configured as a non-cross optical system. In the case of a non-cross optical system, as shown in Figure 4, the first mirror 21a may be a plane mirror, and the display light L reflected by the first mirror 21a may not intersect in the vertical direction V and the horizontal direction H. Also, the first mirror 21a is not limited to a plane mirror but may be a convex mirror. Furthermore, the first mirrors 21 and 21a may be omitted, and the display light L from the display device 10 may be projected directly onto the second mirror 22.

[0058] In the embodiments and modifications described above, the first lens 51 was tilted non-orthogonal to the optical axes of the illumination light IL and the display light L, respectively. However, the invention is not limited to this, and the first lens 51 may be orthogonal to the optical axis of the illumination light IL and tilted non-orthogonal to the optical axis of the display light L by changing the direction of light using a prism sheet (optical path changing means). For example, as shown in Figure 5, the prism sheet 59 is placed between the first lens 51 and the liquid crystal display panel 18 and has a fine prism that reflects the illumination light IL in a direction different from the parallel light propagation direction Z. The prism sheet 59 is not limited to being between the first lens 51 and the liquid crystal display panel 18, but may also be located between the first lens 51 and the second lens 52, or between the second lens 52 and the third lens 53. By using the prism sheet 59, the size of the display device 10a can be reduced. In addition, the illumination size Q can be increased without changing the size of the intermediate image displayed on the display surface 18a. For this reason, in the local dimming function, the number of dimming zones can be increased without changing the pitch of the light source 19.

[0059] In the embodiments described above, the first to third lenses 51 to 53 were formed in the shape of rectangular plates, but the invention is not limited to this, and may be formed in the shape of square, circular, elliptical, or polygonal plates, for example. In the embodiments described above, the head-up display device 100 was mounted on a vehicle 200, but it is not limited to a vehicle 200 and may be mounted on other vehicles such as airplanes or ships. The projection target member onto which the display light L is projected is not limited to the windshield 201, but may be a dedicated combiner.

[0060] In the first embodiment described above, the monochrome liquid crystal panel 12 was capable of switching each pixel 12a between a white display state Sw (light transmittance 100%) and a black display state Sb (light transmittance 0%), but it may also be capable of switching to a gray display state (for example, light transmittance 1% to 99%). This would enable a wide range of dimming. For example, a gradient may be applied to the outer edge of the image display area 18b.

[0061] In the first embodiment described above, the monochrome liquid crystal panel 12 may be provided between the light diffusing member 17 and the liquid crystal display panel 18. In the first embodiment described above, the number of convex lens portions 53a and light sources 19 may be increased or decreased.

[0062] In the first embodiment described above, the monochrome liquid crystal panel 12 had a plurality of pixels 12a arranged in the vertical direction V and the horizontal direction H, but instead of pixels 12a, or in addition to pixels 12a, it may have a plurality of segments that can be switched between a white display state Sw and a black display state Sb. Specifically, as shown in Figure 11, the monochrome liquid crystal panel 112 has a segment area As consisting of a plurality of segments 12s, 12i that can be switched between a white display state Sw and a black display state Sb. Segment 12s is set to the black display state Sb as the background of segment area As. Segment 12i is set to a size larger than pixels 12a within segment 12s, It is formed by a polygon or a circle, etc. Segment 12i is set to a white display state Sw. The image display area 18b of the liquid crystal display panel 18 overlaps within segment 12i. As a result, an image is displayed within segment 12i. In this example, segment area As is located below pixel area Ag, which consists of multiple pixels 12a. Fixed information such as vehicle speed, legal speed, or remaining fuel is displayed at the bottom of the virtual image W, while information that is more diverse and changes more than at the bottom of the virtual image W, such as road route guidance arrows, is displayed at the top of the virtual image W. Therefore, it is preferable to associate segment area As with the bottom of the virtual image W and pixel area Ag with the top of the virtual image W. The positional relationship between the segment region As and the pixel region Ag is not limited to this example; the segment region As may be located above the pixel region Ag, or the segment region As and the pixel region Ag may be aligned horizontally. Furthermore, the entire monochrome liquid crystal panel 112 may be formed by the segment region As. The pixel region Ag of the monochrome liquid crystal panel 112 may be omitted.

[0063] In the first embodiment and its modified form described above, the monochrome liquid crystal panels 12 and 112 were positioned to face the parallel light propagation direction Z across the entire surface of the liquid crystal display panel 18. However, they may also be positioned to face only a portion of the liquid crystal display panel 18 (for example, only the upper part of the liquid crystal display panel 18). In the first embodiment described above, the first to third lenses 51 to 53 are not limited to the configurations disclosed in the first embodiment, but may be any known lens configuration. In the first embodiment described above, a color liquid crystal panel may be provided instead of the monochrome liquid crystal panel 12. In the first embodiment described above, the first and second lenses 51, 52, the monochrome liquid crystal panel 12, the light diffusing member 17, and the liquid crystal display panel 18 may be arranged in a direction perpendicular to the parallel light propagation direction Z. In the first embodiment described above, the lighting device 15 does not necessarily have a local dimming function.

[0064] In the second embodiment described above, the pixels constituting the pixel 12a and the display surface 18a do not necessarily have to match in size, pitch, and aperture ratio. For example, as shown in Figure 14, even if the length 12g of one pixel 12a is longer than the length 18g of one pixel 18g on the display surface 18a, it is sufficient that the white display state Sw is displayed in the shifted area using the method described above. The amount of shift does not necessarily have to match the calculated offset amount G, and it is permissible to add an excess offset amount G1 as shown in Figure 14. It is desirable that the excess offset amount be less than the length 12g. With this configuration, it is possible to suppress the decrease in contrast caused by all of the illumination light IL that has passed through a certain pixel 12a that performs the white display state Sw reaching the non-display area 18c.

[0065] In the second embodiment described above, the monochrome liquid crystal panel 12 (pixel 12a) may be held in a position such that, in a plan view in the normal direction, its outer shape or area center coincides with that of the liquid crystal display panel 18 (display surface 18a) (see Figure 15). Even in this case, the white display state Sw with the aforementioned shift should be performed. This configuration makes it easy to position each panel.

[0066] In the second embodiment described above, the pixel 12a does not need to be large enough to fully cover the warping region 18w. For example, as shown in Figure 16, the warping region 18w generally takes on a shape like a rectangle with its longer sides curved vertically in the direction V, due to reflection from the windshield 201, etc. When a rectangular pixel 12a covers such a warping region 18w, it is preferable that the pixel 12a prioritizes covering the center 18wm (within the dashed line) of each side. In other words, the corners 18wc may be outside the range covered by the pixel 12a. A liquid crystal display panel 18 used in a head-up display device generally displays an image with brightness in a part of a black background, and this image with brightness is more likely to be displayed near the center 18wm than near the corners 18wc. Therefore, it is desirable that the holding position of the pixel 12a be set prioritizing the ability to cover a relatively important part (center 18wm). [Explanation of Symbols]

[0067] 10,10a,10b,10c...display device 12...Monochrome LCD panel, 12a...Pixels 14...Case, 14a...Opening 15…Lighting equipment 16… Circuit board 17…Light Diffusing Member 18...LCD display panel, 18a...Display surface, 18b...Image display area, 18c...Non-display area 18z…Dimming zone, 18F…Off zone, 18L…On zone 19...Light source 21, 21a...First mirror, 22...Second mirror 25... Control Unit 30...Housing, 30c...Opening, 31...Window section 51-53…1st-3rd lenses, 51i, 52i…Induction surface, 51o, 52o…Exit surface, 53a…Convex lens section 59…Prism Sheet 100... Head-up display device 200...Vehicle, 201...Windshield Sb: Biconic lens array surface, Sb1: Microlens section; Sc: Cylindrical lens surface, Sc1: Cylindrical lens section; Sf: Concentric Fresnel lens surface, Sf1: Peak section, Sf2: Fresnel inclined surface, Sf3: Side section SrH: Transverse linear Fresnel lens surface, Sr1: Peak, Sr2: Fresnel inclined surface, Sr3: Side SrV: Longitudinal linear Fresnel lens surface, Sra: Peak, Srb: Fresnel inclined surface, Src: Side H...horizontal direction, V...vertical direction, Z...parallel light propagation direction, θ...angle of light distribution, α...angle, C1, C2, C3...curvature, J...center plane, L...display light, O...center axis, P...lens pitch, Q...illumination size, R...radial direction, W...virtual image, W1...arrangement direction, L1...extension direction, CP...crossing point, IL...illumination light, Pr, Pg...pitch, Sw...white display state, Sb...black display state, As...segment area, Ag...pixel area

Claims

1. A lighting device that emits illumination light, A display panel having an image display area for displaying an image and a non-display area for not displaying an image, and which emits display light upon receiving the illumination light, The system includes a light-transmitting / light-blocking switching panel located between the lighting device and the display panel, which blocks light in the area corresponding to the non-display area and allows light to pass through the area corresponding to the image display area. Display device.

2. The lighting device has a local dimming function that adjusts the brightness for each of the multiple dimming zones. The display device according to claim 1.

3. The light-transmitting switching panel is smaller in size than the multiple dimming zones and comprises multiple pixels arranged in a matrix. The light-transmitting / light-blocking switching panel is configured to be switchable between the light-blocking state and the light-transmitting state for each of the plurality of pixels. The display device according to claim 2.

4. The display panel and the light-transmitting / light-shielding switching panel are inclined with respect to the direction of propagation of the illumination light. The region corresponding to the image display area is positioned at the end closest to the illumination device, shifted by a predetermined offset amount in the direction of the illumination device from the corresponding point reached by the normal extending from the image display area, in the in-plane direction. The display device according to claim 1.

5. The light-transmitting / light-shielding switching panel comprises multiple pixels arranged in a matrix, The offset amount is equal to or greater than the length of one pixel. The display device according to claim 4.

6. The display panel and the light-transmitting / light-shielding switching panel are each rectangular plates, parallel to each other, The offset amount is determined based on one of the values ​​of a*tan(θ), a*tan(θx), or a*tan(θy). a is the distance from a point in the normal direction between the incident surface and the exit surface of the light-transmitting switching panel to a point between the incident surface and the exit surface of the display panel. θ is the inclination angle of the display panel and the light-transmitting / light-shielding switching panel with respect to the direction of travel. θx is the component of the inclination angle of the display panel and the light-transmitting switching panel with respect to the direction of travel, in the short-side direction of the display panel. θy is the longitudinal component of the inclination angle of the display panel and the light-transmitting / light-shielding switching panel with respect to the direction of travel. The display device according to claim 4.

7. The display device according to any one of claims 1 to 6 projects the display light emitted by the display device onto a projection member to display an enlarged projected image of the display panel. Head-up display device.

Images