Head-up display device and mobile unit

Abstract

To miniaturize head-up display devices. [Solution] The head-up display device 200 comprises two or more display devices 100 that emit display light DL, and a mirror unit 50 that reflects the display light DL emitted from the display devices 100. The display device 100 includes an image generation device 41 that generates an image, a projection optical element 42 that forms an intermediate image TI corresponding to the image, and a display control device 80 that controls the display of the image. The intermediate images TI of each display device 100 are arranged with parts of the intermediate images TI superimposed so that they become a single superimposed intermediate image TIs. The display control device 80 performs image processing on the superimposed portion TIx of the intermediate image TI so that it becomes a continuous image, and the mirror unit 50 reflects the display light DL from the superimposed intermediate image TIs so that it is visible to the observer US as a virtual image.

Description

Technical Field

[0001] The present invention relates to a head-up display device that displays a virtual image in the line of sight, and a moving body equipped with the head-up display device.

Background Art

[0002] A head-up display device including a drawing device that displays an image, and a virtual image projection optical system that forms an image of the image displayed by the drawing device on an intermediate screen and converts the formed intermediate screen into a virtual image for projection display is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device of Patent Document 1, the drawing device and the virtual image projection optical system are a set. When projecting a wide image having a high aspect ratio, if a drawing device with a high aspect ratio is used, the drawing device, and thus the entire optical system, becomes large-sized and the cost increases. Regarding the projection of a wide image, it is conceivable to project a plurality of virtual images side by side using a plurality of drawing devices and virtual image projection optical systems. However, there is a possibility that image information is missing at the boundary of the juxtaposed virtual images, which may cause stress to the observer.

Means for Solving the Problems

[0005] A head-up display device in one aspect of the present invention comprises two or more display devices that emit display light, and a mirror unit that reflects the display light emitted from the display devices. Each display device has an image generating device that generates an image, a projection optical element that forms an intermediate image corresponding to the image, and a display control device that controls the display of the image. The intermediate images of each display device are arranged so that a portion of the intermediate image is superimposed to form a single superimposed intermediate image. The display control device performs image processing on the superimposed portion of the intermediate image to make it a continuous image, and the mirror unit reflects the display light from the superimposed intermediate image so that it is perceived by the observer as a virtual image.

[0006] One aspect of the present invention is a mobile body comprising the head-up display device described above. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram illustrating a mobile body incorporating a head-up display device according to the first embodiment. [Figure 2] This is a conceptual diagram explaining an image projection device. [Figure 3] This is a cross-sectional view illustrating a head-up display device. [Figure 4] This is a diagram illustrating the image generation device. [Figure 5] This diagram illustrates the display element, intermediate image, and superimposed intermediate image. [Figure 6] This is a diagram illustrating an image projection device with a diffusion function. [Figure 7] This is a cross-sectional view illustrating a head-up display device according to a second embodiment. [Figure 8] This is a diagram illustrating a head-up display device according to a third embodiment. [Figure 9] This is a diagram illustrating a head-up display device according to a fourth embodiment. [Figure 10] This is a diagram illustrating a head-up display device according to a fifth embodiment. [Figure 11] This is a diagram illustrating a head-up display device according to the sixth embodiment. [Figure 12] This is a diagram illustrating a head-up display device according to the seventh embodiment. [Figure 13] Figure 12 illustrates a specific example of a display device. [Figure 14] This figure illustrates a modified example of the display device shown in Figure 13. [Figure 15] This figure illustrates another specific example of the display device shown in Figure 12. [Figure 16] This figure illustrates a modified example of the display device shown in Figure 15. [Figure 17] This figure illustrates yet another specific example of the display device shown in Figure 12. [Modes for carrying out the invention]

[0008] [First Embodiment] Hereinafter, with reference to the drawings, a head-up display device and the like according to the first embodiment of the present invention will be described.

[0009] Figure 1 is a conceptual diagram illustrating a head-up display device 200 and a mobile body 300 equipped with it. Region AR1 in Figure 1 is a conceptual lateral cross-sectional view illustrating the head-up display device 200, etc. Region AR2 in Figure 1 is a conceptual diagram illustrating the structure and function of the head-up display device 200.

[0010] The head-up display device 200 is mounted on a mobile body 300, for example, an automobile 10, and comprises an image projection device 500 and a mirror unit 50. The image projection device 500 displays any image or picture. The driver DR, who is the observer US, observes the display of the image projection device 500 via the mirror unit 50. The mobile body 300 has an engine and other drive mechanisms for driving the mobile body 300.

[0011] The image projection device 500 is installed so as to be fitted into a recess 11a provided in the dashboard 11 of the vehicle 10, and emits display light DL or image light corresponding to an image or picture including driving-related information or the like upward above the mirror portion 50. The image projection device 500 is covered by a sheet-like and transparent protective cover 11b provided at the upper end of the recess 11a. The mirror portion 50 reflects the display light DL emitted from the display device 100 of the image projection device 500. The mirror portion 50 only needs to reflect a part of the display light DL, and also includes a light-transmissive member such as a half mirror or glass. Specifically, the mirror portion 50 is a film-like member attached to the inner surface of the front window 12 and has the function of a half mirror that transmits part of the light and reflects part of the light. The mirror portion 50 is disposed opposite to the image projection device 500 above the image projection device 500. The transmittance of the mirror portion 50 is set to, for example, 75%, but is not limited thereto. Incidentally, the mirror portion 50 may have the function of a half mirror as the front window 12 itself. Further, in the case of a light-transmissive member, the back side of the mirror portion 50, that is, the back side as viewed from the driver DR, may be painted black within a range that does not obstruct the view. Thereby, the reflectance at the mirror portion 50 becomes substantially 100%, and the display light DL can be observed more clearly.

[0012] FIG. 2 is a conceptual diagram for explaining the image projection device 500. Region BR1 in FIG. 2 is a view of the image projection device 500 from the front, that is, in the +Y direction. Region BR2 in FIG. 2 is a view of the image projection device 500 from the side, that is, in the +X direction. FIG. 3 is a diagram for explaining the image generation device 41 of the image projection device 500. FIG. 4 is a diagram for explaining the display element 41b, the intermediate image TI, and the superimposed intermediate image TIs of the image generation device 41.

[0013] As shown in the region BR1 of FIG. 2, the video projection device 500 includes two or more display devices 100 and a display control device 80 (see FIG. 1). That is, the video projection device 500 is composed of a plurality of display devices 100. In the video projection device 500, the optical system of the entire plurality of display devices 100 is referred to as a display optical system 500a. The video projection device 500 forms a plurality of intermediate images TI by the plurality of display devices 100, and forms a superimposed intermediate image TIs by superimposing the intermediate images TI. The mirror unit 50 shown in FIG. 1 reflects the display light DL from the superimposed intermediate image TIs in the horizontally long reflection region 50a of the mirror unit 50 extending in the X direction so as to be visually recognized as a virtual image by the observer US. As a result, the virtual image becomes a horizontally long video with a high aspect ratio. Thereby, the head-up display device 200 can realize a wide-screen display. In the present embodiment, by enlarging each intermediate image TI with respect to the image of the display element 41b, the boundary portion between the intermediate images TI is filled. The superimposed portion TIx of the intermediate images TI is subjected to image processing by the display control device 80, and a continuous single wide-screen display becomes possible.

[0014] As shown in FIGS. 2 and 3, the display device 100 emits display light DL. The display device 100 has an image generation device 41 that generates a video or an image, and a projection optical element 42 that forms an intermediate image TI. Each display device 100 is arranged such that a part of the intermediate image TI overlaps to form a single superimposed intermediate image TIs.

[0015] As shown in region CR1 of Figure 3, the image generation device 41 includes a light source device 41a and a display element 41b. The display element 41b forms an image or video on a two-dimensional display surface 1a. As shown in Figure 4, the display element 41b has a display area 1d that forms the effective image EI of the image or video. The effective image EI is an image in which optical performance can be ensured. In region CR1 of Figure 3, the display element 41b is an optical modulation element 41c that forms the display light DL, specifically a reflective modulation element 41d. The reflective modulation element 41d modulates the light from the light source device 41a in accordance with the video signal of the display control device 80 shown in Figure 1. Because the reflective modulation element 41d can turn the light on and off, it can achieve very high contrast, and as an in-vehicle display, it can significantly improve the visibility of the virtual image of the head-up display device 200. This can further improve the provision of appropriate information and the effect of reducing stress on the observer US. Examples of reflective modulation elements 41d include DMDs (Digital Mirror Devices) and LCOSs (Liquid Crystal on Silicon). The light source device 41a can be a lamp, an LED (light-emitting diode), a semiconductor laser, or the like.

[0016] The image generating device 41 may have other components. Regions CR2 and CR3 in Figure 3 illustrate a modified example of the image generating device 41.

[0017] As shown in region CR2 of Figure 3, the image generation device 41 includes a light source device 41a and a display element 41b. The display element 41b shown in region CR2 of Figure 3 is an optical modulation element 41c, specifically a transmissive modulation element 41e. The transmissive modulation element 41e modulates the light from the light source device 41a in accordance with the video signal of the display control device 80 shown in Figure 1. The transmissive modulation element 41e can shorten the optical path of the light from the light source device 41a that irradiates the transmissive modulation element 41e, thus enabling miniaturization of the display device 100. Furthermore, if, for example, a liquid crystal element or liquid crystal panel is used as the transmissive modulation element 41e, displays used for other applications can be reused as is, and significant cost reductions can be expected. Examples of transmissive modulation elements 41e include LCDs (Liquid Crystal Displays). The light source device 41a can be, for example, a backlight optical system such as a backlight, or an illumination optical system such as a lamp, LED, or semiconductor laser. In the illustrated example, the light source device 41a is a backlight 141a, and is composed of a light source 1b and a light guide plate 1c.

[0018] As shown in region CR3 of Figure 3, the image generation device 41 has a display element 41b. The display element 41b shown in region CR3 of Figure 3 is a light modulation element 41c, specifically a self-emissive modulation element 41f. Although not shown in the figure, the self-emissive modulation element 41f has multiple light-emitting elements. Each light-emitting element is modulated in accordance with the video signal of the display control device 80 shown in Figure 1. As a result, an illumination optical system for illuminating the display element 41b is unnecessary, making it possible to miniaturize the display device 100 and, consequently, the video projection device 500. As a result, a significant cost reduction can be expected. Examples of self-emissive modulation elements 41f include micro-LEDs and OLEDs (organic light-emitting diodes).

[0019] As shown in Figure 2, the projection optical element 42 forms an intermediate image TI. The projection optical element 42 is positioned between the image generation device 41 and the mirror section 50 (see Figure 1). In this embodiment, the projection optical element 42 is a relay optical element 42a. The relay optical element 42a has one or more projection lenses 2a, 2b. The projection optical element 42 magnifies the image or video formed on the display surface 1a of the display element 41b to form an intermediate image TI on the output side. The intermediate image TI has a rectangular outline. The intermediate image TI is magnified to about 1.2 times the size of the display surface 1a of the display element 41b.

[0020] As shown in Figure 4, in the display optical system 500a of the image projection device 500, the three rectangular display elements 41b are arranged with a predetermined gap between them in the lateral direction, i.e., the X direction. On the other hand, the superimposed intermediate images TIs formed by the image projection device 500 are formed by arranging three rectangular intermediate images TI without any gaps in the lateral direction, i.e., the X direction. In the illustrated example, adjacent intermediate images TI overlap each other and have an overlapping portion TIx, but the edges of adjacent intermediate images TI do not necessarily have to meet to have an overlapping portion TIx.

[0021] The size of each intermediate image TI is larger than the size of the effective image EI of the corresponding display element 41b. This allows for a high degree of freedom in setting the size of the intermediate images TI, ensuring a sufficient overlapping range for the intermediate images TI. As a result, the gaps between virtual images corresponding to each intermediate image TI can be reliably eliminated, significantly improving the visibility of the virtual images. Consequently, the provision of appropriate information and the reduction of stress on the observer (US) can be further improved. In addition, the display device 100, and by extension the image projection device 500, can be miniaturized, leading to significant cost reductions.

[0022] As shown in Figure 5, the display device 100 satisfies the following equation. D1-D2>D3 however, D1: Width of the arrangement direction WX of the display element 41b or optical modulation element 41c of the intermediate image TI. D2: Width of the display element 41b or the optical modulation element 41c in the direction of arrangement WX D3: Spacing WX of the arrangement direction of the display elements 41b or optical modulation elements 41c in the effective image EI of the display element 41b. Here, the alignment direction WX of the display elements 41b or optical modulation elements 41c is the direction in which the display elements 41b or optical modulation elements 41c are aligned. In other words, the alignment direction WX of the display elements 41b or optical modulation elements 41c is the longitudinal direction (X direction) of the intermediate image TI, that is, the lateral direction of the intermediate image TI.

[0023] By satisfying the above formula, a sufficient superposition range of the intermediate image TI can be secured. This ensures that the gaps between virtual images corresponding to each intermediate image TI are eliminated, significantly improving the visibility of the virtual images. As a result, the provision of appropriate information and the reduction of stress on the observer (US) can be further improved.

[0024] In this embodiment, as shown in Figure 6, the image projection device 500 or display device 100 has a diffusion optical element 43 having a diffusion function at the position where the intermediate image TI is formed. Specifically, as shown in Figure 6, the image projection device 500 has a diffusion screen 43a at the position where the intermediate image TI is formed. In this case, the image projection device 500 satisfies the following equation. θ1 < θ2 however, θ1: Incident angle of light (incident focusing angle) at the diffuse optical element 43 θ2: Light emission angle (emission and radiation angle) in the diffuse optical element 43

[0025] By incorporating a diffusion function at the position where the intermediate image TI is formed, the exit angle θ2 can be widened compared to the incident angle θ1, thereby securing a wider field of view. This significantly improves the visibility of the virtual image, further enhancing the provision of appropriate information and reducing stress on the observer (US).

[0026] The diffusing optical element 43 may be omitted as appropriate.

[0027] The display control device 80 shown in Figure 1 controls the display of the image shown on the display surface 1a of the display element 41b. The display control device 80 performs image processing so that the superimposed portion TIx (see Figure 4, etc.) of the intermediate image TI becomes a continuous image. Examples of image processing include blending. For blending, for example, the technology disclosed in Japanese Patent Application Publication No. 11-98439 can be used.

[0028] The optical path of the head-up display device 200 shown in Figure 1 will be described below. In the video projection device 500, the display light DL from the video or image formed on the display surface 1a (see Figure 2, etc.) of the display element 41b of the display device 100 is partially reflected by the mirror section 50 via the projection optical element 42 and incident on the pupil PU of the observer US or driver DR. In other words, the driver DR can observe the display light DL reflected by the mirror section 50, that is, the display image DI as a virtual image in front of the automobile 10. Here, the video projection device 500 forms an intermediate image TI using multiple display devices 100, and superimposes multiple intermediate images TI to form superimposed intermediate images TIs. Therefore, the display image DI becomes a widescreen horizontally elongated screen corresponding to the superimposed intermediate images TIs.

[0029] Furthermore, the driver DR can observe the external light transmitted through the mirror unit 50, that is, the real image of an object in front of them. As a result, the driver DR can observe a display image (virtual image) DI, which includes various information such as driving-related information, formed by the reflection of the display light DL at the mirror unit 50, superimposed on the external image or see-through image behind the front windshield 12, as if it were behind the steering wheel 14 or the front windshield 12.

[0030] The head-up display device 200 described above comprises two or more display devices 100 that emit display light DL, and a mirror unit 50 that reflects the display light DL emitted from the display devices 100. The display device 100 includes an image generation device 41 that generates an image, a projection optical element 42 that forms an intermediate image TI corresponding to the image, and a display control device 80 that controls the display of the image. The intermediate images TI of each display device 100 are arranged with parts of the intermediate images TI superimposed so that they become a single superimposed intermediate image TIs. The display control device 80 performs image processing on the superimposed portion TIx of the intermediate image TI so that it becomes a continuous image, and the mirror unit 50 reflects the display light DL from the superimposed intermediate image TIs so that it is visible to the observer US as a virtual image.

[0031] In the head-up display device 200 described above, a widescreen virtual image is displayed using superimposed intermediate images TIs formed by connecting multiple intermediate images TI. This allows for a smaller overall size and lower cost compared to displaying a virtual image with a single display device 100. Furthermore, by forming superimposed intermediate images TIs, the boundaries corresponding to the gaps between adjacent display devices 100 are not visible in the virtual image display area, providing a continuous widescreen. Therefore, when displaying maps or images that span multiple display areas, necessary information is not lost or unnatural images are not displayed at the boundaries. This enables the provision of appropriate information and reduces stress on the observer (US). In addition, there is no need for video content or display layout designs that avoid boundaries, resulting in cost reduction through simplified content creation and the ability to freely design and express the image.

[0032] The mobile body 300 described above is equipped with the head-up display device 200. This makes it possible to realize a mobile body 300 equipped with a miniaturized head-up display device 200. Furthermore, the display device 100 constituting the head-up display device 200 can use a general-purpose image generation device 41 even when mounted on the mobile body 300, thereby reducing costs.

[0033] [Second Embodiment] The head-up display device of the second embodiment will now be described. The head-up display device of the second embodiment is a modified version of the head-up display device of the first embodiment, and the parts common to the head-up display device of the first embodiment will not be described.

[0034] As shown in Figure 7, in this embodiment, the relay optical element 42a, which is the projection optical element 42, has a plurality of projection lenses 2a, 2b, and 2c that adjust the size of the intermediate image TI. Specifically, the relay optical element 42a has three projection lenses 2a, 2b, and 2c and a folding mirror 45. The folding mirror 45 is positioned between the magnifying projection lens 2c and the intermediate image TI.

[0035] In the head-up display device 200 of this embodiment, the projection optical element 42 has multiple projection lenses 2a, 2b, and 2c, which makes it easier to adjust the magnification and focus, allows for a high degree of freedom in setting the size of the intermediate image TI, and ensures a sufficient superposition range for the intermediate image TI. As a result, the gaps between virtual images corresponding to each intermediate image TI can be reliably eliminated, and the visibility of the virtual images can be significantly improved. Consequently, the effect of providing appropriate information and reducing stress on the observer (US) can be further improved.

[0036] [Third Embodiment] The head-up display device of the third embodiment will now be described. The head-up display device of the third embodiment is a modified version of the head-up display device of the first embodiment, and the parts that are common to the head-up display device of the first embodiment will not be described.

[0037] As shown in Figure 8, in this embodiment, superimposed intermediate images TIs are formed by shifting adjacent intermediate images TIs so that they move closer to each other, thereby filling in the boundary portions of the intermediate images TIs.

[0038] In the video projection device 500, at least one of the multiple display devices 100 shifts the central axis AX of the optical modulation element 41c, which is a display element 41b, in the direction WX of the arrangement of the optical modulation elements 41c with respect to the optical axis OA of the projection optical element 42, so as to superimpose an intermediate image TI. Therefore, adjacent display devices 100 differ in either the amount of shift or the direction of shift with respect to the central axis AX of the display element 41b or the optical modulation element 41c.

[0039] In the head-up display device 200 of this embodiment, the position of the intermediate image TI can be set with a high degree of freedom, so that the superposition range of the intermediate image TI can be sufficiently secured. As a result, the gaps between virtual images corresponding to each intermediate image TI can be reliably eliminated, and the visibility of the virtual images can be significantly improved. Consequently, the effect of providing appropriate information and reducing stress on the observer (US) can be further improved.

[0040] [Fourth Embodiment] The head-up display device of the fourth embodiment will now be described. The head-up display device of the fourth embodiment is a modified version of the head-up display device of the first embodiment, and the parts common to the head-up display device of the first embodiment will not be described.

[0041] As shown in Figure 9, in this embodiment, superimposed intermediate images TIs are formed by tilting one or more intermediate images TI to fill the boundary portions of the intermediate images TI.

[0042] Specifically, adjacent intermediate images TI have different angles with respect to the wide axis WA, which is parallel to the alignment direction WX of the optical modulation elements 41c. In other words, the inclination of the central axis BX of each intermediate image TI is different. The wide axis WA is the axis that extends in the longitudinal or lateral direction, i.e., the X direction, of the reference intermediate image TI among the multiple intermediate images TI. The inclination angle of the intermediate images TI is the angle that maintains the depth of field.

[0043] In the example shown in Figure 9, of the three intermediate images TI, the reference middle intermediate image TI is not tilted, the left intermediate image TI is tilted clockwise at an angle α with respect to the wide axis WA, and the right intermediate image TI is tilted counterclockwise at an angle α with respect to the wide axis WA. The superimposed intermediate images TIs formed by the image projection device 500 are slightly bent, but the virtual image visible through the mirror section 50 is approximately planar.

[0044] If the angle of each intermediate image TI can be appropriately set, a sufficient overlap range of the intermediate images TI can be ensured. This ensures that the gaps between virtual images corresponding to each intermediate image TI are eliminated, significantly improving the visibility of the virtual images. As a result, the provision of appropriate information and the reduction of stress on the observer (US) can be further improved.

[0045] [Fifth Embodiment] The head-up display device of the fifth embodiment will now be described. The head-up display device of the fifth embodiment is a modified version of the head-up display device of the first embodiment, and the parts common to the head-up display device of the first embodiment will not be described.

[0046] As shown in regions DR1 and DR2 of Figure 10, in this embodiment, the size of the intermediate image TI formed by each display device 100 is equal to the size of the effective image EI or display region 1d of the display element 41b of the image generation device 41. In other words, when comparing the intermediate image TI with the effective image EI, the intermediate image TI projected onto the original image, the effective image EI, is at equal magnification. Furthermore, the divergence angle β of the light emitted from the display element 41b and the divergence angle γ of the light incident on the position of the intermediate image TI are the same or approximately the same.

[0047] In the head-up display device 200 of this embodiment, since the size of the effective image EI of the display element 41b and the size of the intermediate image TI are the same, the light divergence angle can be maintained, and a wide viewing angle can be secured. Furthermore, since the viewing angle can be secured without adding a diffusion effect to widen the viewing angle after the intermediate image TI is formed, the loss of brightness is also small. Therefore, the visibility of the virtual image can be significantly improved, and the effect of providing appropriate information and reducing stress on the observer US can be further enhanced.

[0048] When the size of the effective image EI of the display element 41b and the size of the intermediate image TI are the same, the method of superimposing the intermediate image TI is to shift the display element 41b or the optical modulation element 41c, as shown in region DR1 of Figure 10, or to tilt the intermediate image TI, as shown in region DR2 of Figure 10.

[0049] In this embodiment, it is not necessary to provide a diffusion member, but a diffusion optical element 43 as shown in Figure 6 may be provided.

[0050] [Sixth Embodiment] The head-up display device of the sixth embodiment will now be described. The head-up display device of the sixth embodiment is a modified version of the head-up display device of the first embodiment, and the parts common to the head-up display device of the first embodiment will not be described.

[0051] As shown in regions ER1 and ER2 of Figure 11, in this embodiment, the image projection device 500 superimposes an intermediate image TI using an optical system including a retroreflective member 46 to achieve a horizontal or widescreen virtual image. In this embodiment, the size of the intermediate image TI formed by each display device 100 of the image projection device 500 is equal to the size of the effective image EI or display area 1d of the display element 41b of the image generation device 41. The image projection device 500 or the display device 100 has a transmission diffusion member 143 at the position where the intermediate image TI is formed. The transmission diffusion member 143 is a transmission member containing a diffusion material. The transmission diffusion member 143 may be the same as the diffusion optical element 43 (diffusion screen 43a) shown in Figure 6. By providing the transmission diffusion member 143, it is possible to prevent the boundary portion from shifting depending on the viewing angle of the observer US.

[0052] In the display device 100, the projection optical element 42 includes a polarizing beam splitter 42c, a quarter-wave plate 42d, and a retroreflective member 46 as relay optical elements 42a. The retroreflective member 46 has an assembly of corner cubes (not shown), and the corner cubes reflect the incident light in a direction parallel to and opposite to the direction of incidence. In this embodiment, the image generation device 41 emits a predetermined polarization. Specifically, a polarizer that transmits a predetermined polarization, such as S polarization, is provided on the emission side of the display element 41b. In this case, the polarizing beam splitter 42c is designed to reflect S polarization and transmit P polarization. The polarization characteristics of the polarizing beam splitter 42c can be appropriately changed according to the polarization emitted from the image generation device 41.

[0053] The image generating device 41 emits a predetermined polarization, such as S-polarization, as display light DL and irradiates the polarization beam splitter 42c. The display light DL irradiated by the polarization beam splitter 42c is reflected by the polarization beam splitter 42c and heads toward the quarter-wave plate 42d. The S-polarized display light DL becomes circularly polarized as it passes through the quarter-wave plate 42d. Subsequently, the light emitted at the same angle as the incident angle by the retroreflective member 46 passes through the quarter-wave plate 42d again and becomes P-polarized. The P-polarized light passes through the polarization beam splitter 42c and creates an image conjugate to the display element 41b, i.e., an intermediate image TI, on the transmission diffusion member 143, and becomes diffused light as it passes through the transmission diffusion member 143. As a result, multiple intermediate images TI are superimposed, and superimposed intermediate images TIs are formed.

[0054] As described above, in the head-up display device 200 of this embodiment, when the intermediate image TI is viewed from the observer US side, the display element 41b is not visible on the physical extension of the optical path. Therefore, stray light and ghost light are not visible directly from the display element 41b without going through the intermediate image TI, and a high-quality image can be displayed. Consequently, the visibility of the virtual image can be significantly improved, and the effect of providing appropriate information and reducing stress on the observer US can be further enhanced.

[0055] [Seventh Embodiment] The head-up display device of the seventh embodiment will now be described. The head-up display device of the seventh embodiment is a modified version of the head-up display device of the first embodiment, and the parts common to the head-up display device of the first embodiment will not be described.

[0056] As shown in regions FR1 and FR2 of Figure 12, in this embodiment, the image projection device 500 superimposes an intermediate image TI using an optical system including a plane-symmetric imaging optical element 47 to achieve a horizontally elongated or widescreen virtual image. In this embodiment, the size of the intermediate image TI formed by each display device 100 of the image projection device 500 is equal to the size of the effective image EI or display area 1d of the display element 41b of the image generation device 41. The image projection device 500 has a transmission diffusion member 143 at the position where the intermediate image TI is formed. The transmission diffusion member 143 may be the same as the diffusion optical element 43 (diffusion screen 43a) shown in Figure 6. By providing the transmission diffusion member 143, it is possible to prevent the boundary portion from shifting depending on the viewing angle of the observer US.

[0057] In the display device 100, the projection optical element 42 has a plane-symmetric imaging optical element 47 as a relay optical element 42a. The plane-symmetric imaging optical element 47 forms an image symmetrically in the plane with light from the image generation device 41 on either side of the plane-symmetric imaging optical element 47.

[0058] In the head-up display device 200 of this embodiment, the distance between the intermediate image TI and the image generation device 41, specifically the display element 41b, can be minimized, resulting in a very compact structure and significant cost reduction.

[0059] Three types of symmetric imaging optical elements 47 can be given as examples of the following methods.

[0060] (1) Single MLA system As shown in Figure 13, in the display device 100, the projection optical element 42 has a microlens array 47a as a plane-symmetric imaging optical element 47. The microlens array 47a has microlenses 7a arranged at positions corresponding to each pixel 1e of the display element 41b.

[0061] Light from the light source device 41a, specifically the backlight 141a, irradiates the pixels 1e of the display element 41b with a narrow beam angle. Each pixel 1e of the display element 41b can switch the incident light on and off using a liquid crystal or the like. Although not shown in the figures, if the display element 41b is a liquid crystal element or liquid crystal panel, polarizing plates arranged in crossed nicols are provided on the incident and exit sides.

[0062] Light emitted from each pixel 1e is incident on the microlens array 47a corresponding to each pixel 1e. The divergence angle of the incident light to the microlens array 47a is the same as the narrow-angle divergence angle of the backlight 141a. A transmission-diffusing member 143 is positioned at the focal length of the microlens array 47a. The focal length of the microlens array 47a is the position where the light beam emitted from the microlens array 47a is most concentrated. The transmission-diffusing member 143 converts the light stored at the narrow angle into diffused light. From the observer's perspective (US), the image of the surface of this transmission-diffusing member 143, i.e., the intermediate image TI, can be recognized as a conjugate image to the image of the display element 41b.

[0063] In the single MLA method, an intermediate image TI can be obtained with a simple configuration (a microlens array 47a is placed on the output side of the display element 41b). Therefore, the image projection device 500 can be made into a thin unit, and the distance between the intermediate image TI and the image generation device 41 can be minimized. In this way, the head-up display device 200 has a very compact structure, and a significant cost reduction can be expected.

[0064] As shown in Figure 14, the display device 100 can apply a single MLA method to the magnification projection system that magnifies the intermediate image TI on the display element 41b. Specifically, the microlens array 47a magnifies the intermediate image TI by changing the size of the microlenses 7a or by shifting the position of the microlenses 7a.

[0065] (2) Double MLA system As shown in Figure 15, in the display device 100, the projection optical element 42 is a plane-symmetric imaging optical element 47 and includes an incident microlens array 47b, an aperture 48, and an exit microlens array 47c. The incident microlens array 47b and the exit microlens array 47c have microlenses 7b and 7c arranged at positions corresponding to each pixel 1e of the display element 41b. The aperture 48 is a light-shielding plate 8a with multiple apertures 8b. The apertures 8b are arranged at positions corresponding to each pixel 1e of the display element 41b.

[0066] Light from the light source device 41a, specifically the backlight 141a, irradiates the pixels 1e of the display element 41b with a narrow divergence angle. Each pixel 1e of the display element 41b can switch the incident light on and off using liquid crystal or the like. Although not shown in the figures, if the display element 41b is a liquid crystal element or liquid crystal panel, polarizing plates arranged in crossed nicols are provided on the incident and exit sides.

[0067] Light emitted from each pixel 1e is incident on the incident microlens array 47b corresponding to each pixel 1e. The divergence angle of the incident light to the incident microlens array 47b is preserved from the narrow-angle divergence angle of the backlight 141a. An aperture 48 is positioned at the focal length of the incident microlens array 47b. The aperture 48 prevents stray light generated by pixels 1e, etc. The light that has diverged through the aperture 48 is collimated and focused by passing through the exit microlens array 47c, forming a conjugate image with the pixel 1e. A transmission-diffusing member 143 positioned at the location where the conjugate image is formed converts the light preserved at the narrow angle into diffused light. From the observer US side, the image of the surface of this transmission-diffusing member 143, i.e., the intermediate image TI, can be recognized as a conjugate image with the image of the display element 41b.

[0068] The double MLA system allows for the blocking of stray light and ghosting at aperture 48, resulting in high-contrast images. This significantly improves the visibility of virtual images, further enhancing the provision of appropriate information and reducing driver stress.

[0069] As shown in Figure 16, the display device 100 can apply a double MLA method to the magnification projection system that magnifies the intermediate image TI on the display element 41b. Specifically, the microlens arrays 47b and 47c magnify the intermediate image TI by changing the size of the microlenses 7b and 7c or by shifting the positions of the microlenses 7b and 7c.

[0070] (3) Micro-mirror method As shown in Figure 17, in the display device 100, the projection optical element 42 has a mirror array element 47d as a plane-symmetric imaging optical element 47. The mirror array element 47d has a plurality of micro-mirrors (not shown). Examples of micro-mirrors include, for example, a two-sided corner reflector and a two-sided orthogonal reflector. Light incident on the mirror array element 47d is reflected twice by the micro-mirrors and emitted. A specific example of the micro-mirror system can be used, which is the technology disclosed in Japanese Patent Application Publication No. 2021-139932.

[0071] Light from the display element 41b forms an intermediate image TI symmetrically across the mirror array element 47d. A transmission and diffusion member 143 is positioned where the intermediate image TI is formed.

[0072] In the micro-mirror method, an intermediate image TI can be obtained with a simple configuration (a mirror array element 47d is placed on the emission side of the display element 41b). Therefore, the image projection device 500 can be made into a thin unit, and the distance between the intermediate image TI and the image generation device 41 can be minimized.

[0073] [Other matters] The structure described above is an example, and can be modified in various ways as long as similar functionality can be achieved.

[0074] The optical system of the display device 100 is merely an example, and the optical configuration can be changed as appropriate. The configurations of the image generating device 41 and the projection optical element 42 can also be changed as appropriate.

[0075] The projection optical element 42 may have a concave mirror instead of projection lenses 2a, 2b, and 2c.

[0076] The display devices 100 that make up the video projection device 500 are not limited to three; they may be two, four or more, or any number of devices.

[0077] The image projection device 500 does not always have to form superimposed intermediate images TIs. Alternatively, the image projection device 500 may project an image of a combination of superimposed intermediate images TIs and an intermediate image TI that is not superimposed onto the mirror section 50. For example, the superimposed intermediate images TIs or the intermediate image TI to be displayed as a virtual image may be switched as appropriate by changing the size of the image displayed on the display surface 1a of the display element 41b, or by moving or changing the components of the display device 100.

[0078] The observer US is not limited to the driver DR; it can also be any other passenger sitting in the front passenger seat, back seat, etc.

[0079] The mirror unit 50 may be a separate, independent unit installed separately from the front windshield 12.

[0080] The head-up display device 200 is not limited to being mounted on the mobile body 300; it can be used for other purposes as long as it displays the image of the display element 41b as a virtual image.

[0081] [Summary of this disclosure] A summary of this disclosure is provided below.

[0082] (Note 1) The device comprises two or more display devices that emit display light, and a mirror section that reflects the display light emitted from the display devices. The display device comprises an image generation device that generates an image, a projection optical element that forms an intermediate image corresponding to the image, and a display control device that controls the display of the image. The intermediate images of each display device are arranged so that a portion of the intermediate image is superimposed on each other, so that they form a single superimposed intermediate image. The display control device applies image processing to the superimposed portion of the intermediate image so that it becomes a continuous image. The mirror portion reflects the display light from the superimposed intermediate image so that it is perceived by the observer as a virtual image. Head-up display device. By displaying a widescreen virtual image using superimposed intermediate images created by connecting multiple intermediate images, it is possible to achieve a smaller overall size and lower cost compared to displaying virtual images with a single display device. Furthermore, by forming superimposed intermediate images, the boundaries corresponding to the gaps between adjacent display devices are not visible within the display area of ​​the virtual image, providing a continuous widescreen. Therefore, when displaying maps or images that span multiple display areas, necessary information is not lost or unnatural images are not displayed at the boundaries. This enables the provision of appropriate information and reduces stress on the viewer. In addition, there is no need for video content or display layout designs that avoid the boundaries, resulting in cost reduction through simplified content creation and the ability to freely design and express the image.

[0083] (Note 2) The image generation device has a reflective modulation element as the optical modulation element that forms the display light. The head-up display device described in Appendix 1. Reflective modulation elements can switch light on and off, allowing for very high contrast and significantly improving the visibility of virtual images. This further enhances the provision of appropriate information and reduces observer stress.

[0084] (Note 3) The image generation device has a transmissive modulation element as an optical modulation element that forms the display light. The head-up display device described in Appendix 1. Transmissive modulation elements allow for a shorter optical path for light irradiated onto the element, thus enabling miniaturization of display devices. Furthermore, if liquid crystal elements, for example, are used as transmissive modulation elements, general-purpose displays can be reused, leading to significant cost reductions.

[0085] (Note 4) The image generation device has a plurality of light-emitting elements as light modulation elements that form the display light. The head-up display device described in Appendix 1. This eliminates the need for an illumination optical system in the image generation device, allowing for miniaturization of the display device. As a result, significant cost reductions can be expected.

[0086] (Note 5) The size of the intermediate image is larger than the size of the effective image of the optical modulation element. A head-up display device as described in any one of the appendices 2 to 4. In this case, the size of the intermediate image can be set with a high degree of freedom, ensuring a sufficient overlapping range for the intermediate images. This reliably eliminates the gaps between virtual images corresponding to each intermediate image, significantly improving the visibility of the virtual images. As a result, the effectiveness of providing appropriate information and reducing observer stress can be further enhanced. In addition, the display device can be miniaturized, leading to significant cost reductions.

[0087] (Note 6) The size of the intermediate image is equal to the size of the effective image of the optical modulation element. A head-up display device as described in any one of the appendices 2 to 4. In this case, since the size of the effective image of the optical modulator and the size of the intermediate image are the same, the angle of light diffusion can be maintained, and a wide field of view can be secured. Furthermore, since the field of view can be secured without adding a diffusion effect to widen the field of view after the intermediate image is formed, the loss of brightness can be reduced. As a result, the visibility of the virtual image can be significantly improved, and the effect of providing appropriate information and reducing observer stress can be further enhanced.

[0088] (Note 7) The projection optical element has a plurality of projection lenses that adjust the size of the intermediate image. A head-up display device as described in any one of the appendices 1 to 6. In this case, the magnification and focus can be easily adjusted, and the size of the intermediate image can be set with a high degree of freedom, ensuring a sufficient overlapping range of the intermediate images. This reliably eliminates the gaps between virtual images corresponding to each intermediate image, significantly improving the visibility of the virtual images. As a result, the effectiveness of providing appropriate information and reducing observer stress can be further enhanced.

[0089] (Note 8) The projection optical element has a retroreflective member, A head-up display device as described in any one of the appendices 1 to 6. In this case, when the observer views the intermediate image, the image generating device is not visible on the physical extension of the optical path. Therefore, stray light and ghost light are not visible directly from the image generating device, bypassing the intermediate image, and a high-quality image can be displayed. This significantly improves the visibility of the virtual image, further enhancing the provision of appropriate information and reducing observer stress.

[0090] (Note 9) The projection optical element has a plane-symmetric imaging optical element. A head-up display device as described in any one of the appendices 1 to 6. In this case, the distance between the intermediate image and the image generation device can be minimized, resulting in a very compact structure and significant cost reductions.

[0091] (Note 10) At least one of the plurality of the display devices shifts the central axis of the optical modulation element in the direction of the arrangement of the optical modulation elements with respect to the optical axis of the projection optical element so as to superimpose the intermediate image. A head-up display device as described in any one of the appendices 1 through 7. In this case, the position of the intermediate image can be set with a high degree of freedom, ensuring a sufficient overlapping range for the intermediate images. This reliably eliminates the gaps between virtual images corresponding to each intermediate image, significantly improving the visibility of the virtual images. As a result, the effectiveness of providing appropriate information and reducing observer stress can be further enhanced.

[0092] (Note 11) The following equation is satisfied: A head-up display device as described in any one of the appendices 2 to 5, 7, 9, and 10. D1-D2>D3 however, D1: Width of the optical modulation elements in the direction of alignment of the intermediate image. D2: Width of the effective image of the optical modulation elements in the direction of alignment of the optical modulation elements. D3: Spacing of the optical modulation elements in the direction of alignment of the optical modulation elements in the effective image of the optical modulation elements. By satisfying this formula, a sufficient overlapping range of intermediate images can be ensured. This reliably eliminates the gaps between virtual images corresponding to each intermediate image, significantly improving the visibility of the virtual images. As a result, the provision of appropriate information and the reduction of observer stress can be further improved.

[0093] (Note 12) The adjacent intermediate images have different angles with respect to the wide axis parallel to the direction of arrangement of the optical modulation elements. A head-up display device as described in any one of the appendices 2 to 9 and 11. By appropriately setting the angle of each intermediate image, a sufficient overlapping range of the intermediate images can be ensured. This reliably eliminates the gaps between virtual images corresponding to each intermediate image, significantly improving the visibility of the virtual images. As a result, the effectiveness of providing appropriate information and reducing observer stress can be further enhanced.

[0094] (Note 13) A diffusion optical element having a diffusion function is placed at the position where the intermediate image is formed, satisfying the following equation: A head-up display device as described in any one of the appendices 1 through 12. θ1 < θ2 however, θ1: Incidence angle of light in the diffuse optical element. θ2: Light emission angle in the diffusing optical element. By incorporating a diffusion function at the position where the intermediate image is formed, the exit angle θ2 can be widened compared to the incident angle θ1, thereby securing a wider field of view. This significantly improves the visibility of the virtual image, further enhancing the provision of appropriate information and reducing observer stress.

[0095] (Note 14) A head-up display device as described in any one of the appendices 1 to 13, A mobile object. This makes it possible to realize a mobile device equipped with a miniaturized head-up display device. Furthermore, the display device that makes up the head-up display device can use a general-purpose image generation device even when mounted on a mobile device, thus reducing costs. [Explanation of Symbols]

[0096] 1a...Display surface, 1d...Display area, 2a,2b,2c...Projection lens, 41...Image generation device, 41a...Light source device, 41b...Display element, 41c...Optical modulation element, 41d...Reflective modulation element, 41e...Transmissive modulation element, 41f...Self-emitting modulation element, 42...Projection optical element, 42a...Relay optical element, 42c...Polarizing beam splitter, 43...Diffusion optical element, 43a...Diffusion screen, 45...Bent mirror, 46...Retroreflective member, 47...Symmetrical imaging optical element, 47a...Microlens array, 47b...Incident microlens array, 4 7c...Exit-side microlens array, 47d...Mirror array element, 48...Aperture, 50...Mirror section, 50a...Reflection area, 80...Display control device, 100...Display device, 143...Transmission diffusion member, 200...Head-up display device, 300...Moving body, 500...Image projection device, 500a...Display optical system, AX...Central axis, BX...Central axis, DI...Display image, DL...Display light, DR...Driver, EI...Effective image, OA...Optical axis, TI...Intermediate image, TIs...Superimposed intermediate image, TIx...Superimposed portion, US...Observer, WA...Wide axis, WX...Alignment direction of optical modulation elements

Claims

1. The device comprises two or more display devices that emit display light, and a mirror section that reflects the display light emitted from the display devices. The display device comprises an image generation device that generates an image, a projection optical element that forms an intermediate image corresponding to the image, and a display control device that controls the display of the image. The intermediate images of each display device are arranged so that a portion of the intermediate image is superimposed on each other, so that they form a single superimposed intermediate image. The display control device applies image processing to the superimposed portion of the intermediate image so that it becomes a continuous image. The mirror portion reflects the display light from the superimposed intermediate image so that it is perceived by the observer as a virtual image. Head-up display device.

2. The image generation device has a reflective modulation element as the optical modulation element that forms the display light. The head-up display device according to claim 1.

3. The image generation device has a transmissive modulation element as an optical modulation element that forms the display light. The head-up display device according to claim 1.

4. The image generation device has a plurality of light-emitting elements as light modulation elements that form the display light. The head-up display device according to claim 1.

5. The size of the intermediate image is larger than the size of the effective image of the optical modulation element. The head-up display device according to any one of claims 2 to 4.

6. The size of the intermediate image is equal to the size of the effective image of the optical modulation element. The head-up display device according to any one of claims 2 to 4.

7. The projection optical element has a plurality of projection lenses that adjust the size of the intermediate image. The head-up display device according to claim 1.

8. The projection optical element has a retroreflective member, The head-up display device according to claim 1.

9. The projection optical element has a plane-symmetric imaging optical element. The head-up display device according to claim 1.

10. At least one of the plurality of the display devices shifts the central axis of the optical modulation element in the direction of the arrangement of the optical modulation elements with respect to the optical axis of the projection optical element so as to superimpose the intermediate image. The head-up display device according to any one of claims 2 to 4.

11. The following equation is satisfied: The head-up display device according to any one of claims 2 to 4. D1-D2 > D3 however, D1: Width of the optical modulation elements in the direction of arrangement of the intermediate image D2: Width of the effective image of the optical modulation elements in the direction of alignment of the optical modulation elements. D3: The spacing between the optical modulation elements in the direction of alignment of the effective image of the optical modulation elements.

12. The adjacent intermediate images have different angles with respect to the wide axis parallel to the direction of arrangement of the optical modulation elements. The head-up display device according to any one of claims 2 to 4.

13. A diffusion optical element having a diffusion function is placed at the position where the intermediate image is formed, satisfying the following equation: The head-up display device according to claim 1. θ1 < θ2 however, θ1: Incidence angle of light in the diffuse optical element. θ2: Light emission angle in the diffusing optical element.

14. A head-up display device as described in claim 1, A mobile object.

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