JP7501533B2 - Head-up display device - Google Patents

Description

The present disclosure relates to a head-up display device that is used in a vehicle and superimposes an image onto the vehicle's foreground for viewing.

Patent Document 1 discloses a head-up display device that includes a display that displays a main image facing the vehicle occupants, and a projector and a screen that displays a sub-image, one end of which is adjacent to the main image and the other end of which is positioned in front of the one end.

JP 2016-71051 A

The head-up display device of Patent Document 1 requires two displays: a display for displaying an image facing the driver, and a display (projector and screen) that is positioned along the road surface, which is expected to increase parts costs, etc.

A summary of certain embodiments disclosed herein is provided below. It should be understood that these aspects are presented merely to provide the reader with an overview of these particular embodiments, and are not intended to limit the scope of the disclosure. Indeed, the disclosure may encompass a variety of aspects that are not set forth below.

The present disclosure relates to providing a head-up display device that has a display area that follows the road surface and a display area that is tilted upward at an angle relative to the road surface, while keeping costs down.

Therefore, the head-up display device of the embodiment described in this specification is a head-up display device that allows the viewer to view a virtual image in a virtual image display area along the fore-and-aft direction of the vehicle, the virtual image display area being composed of a distant virtual image area and a near virtual image area that is closer to the viewer than the distant virtual image area, the display surface of the display device includes a display surface distant area corresponding to the distant virtual image area and a display surface near area corresponding to the near virtual image area, the display surface near area being arranged at an angle with respect to the optical axis of the image light directed toward the viewer so that the near virtual image area is arranged along the fore-and-aft direction of the vehicle, and the display surface distant area is arranged bent with respect to the display surface near area so that the distant virtual image area rises up towards the viewer with respect to the near virtual image area (153).

FIG. 1 is a diagram illustrating an example of application of a head-up display device to a vehicle according to some embodiments. FIG. 1 illustrates a configuration of a head-up display device according to some embodiments. FIG. 13 is a diagram showing an arrangement of a relay optical system and a display surface in a comparative example. FIG. 3B is a diagram showing the arrangement of virtual image display areas generated in the comparative example of FIG. 3A . FIG. 2 illustrates an arrangement of relay optics and a display surface according to some embodiments. FIG. 4B is a diagram showing the arrangement of virtual image display areas generated in the embodiment of FIG. 4A. 11A to 11D are diagrams illustrating the relationship between the position in the depth direction (Z-axis direction) of the virtual image display area and the tilt angle according to some embodiments. 11A to 11D are diagrams illustrating the relationship between the position in the depth direction (Z-axis direction) of the virtual image display area and the tilt angle according to some embodiments. 11A to 11D are diagrams illustrating the relationship between the position in the depth direction (Z-axis direction) of the virtual image display area and the tilt angle according to some embodiments. FIG. 2 illustrates an arrangement of virtual image display areas in accordance with some embodiments. FIG. 2 illustrates an arrangement of virtual image display areas in accordance with some embodiments. FIG. 2 illustrates an arrangement of virtual image display areas in accordance with some embodiments. FIG. 2 illustrates an arrangement of relay optics and a display surface according to some embodiments.

Below, in Figures 1 and 2, an explanation is provided of the configuration of an exemplary vehicle display system and head-up display device. In addition, in Figures 3A and 3B, an explanation is provided of a comparative example, and in Figures 4A to 8, an explanation is provided of the configuration of this embodiment. Note that the present invention is not limited to the following embodiments (including the contents of the drawings). Of course, modifications (including the deletion of components) can be made to the following embodiments. In addition, in the following explanation, explanations of known technical matters will be omitted as appropriate in order to facilitate understanding of the present invention.

Refer to Figure 1. The vehicle display system 10 is composed of a HUD device 20 and a display control device 30 that controls the HUD device 20. In the description of this embodiment, the left-right direction when a viewer (driver 4) seated in the driver's seat of the vehicle 1 faces forward of the vehicle 1 is defined as the X-axis (the left direction is the X-axis positive direction), the up-down direction is defined as the Y-axis (the up direction is the Y-axis positive direction), and the front-rear direction is defined as the Z-axis (the forward direction is the Z-axis positive direction).

The HUD device 20 in the vehicle display system 10 is a head-up display (HUD: Head-Up Display) device provided in the dashboard 5 of the vehicle 1. The HUD device 20 emits image light 40 toward the windshield 2 (one example of a projection target), and generates an eye box (not shown) of a predetermined area by the image light 40 reflected by the windshield 2. The driver 4 can view the entire image displayed by the HUD device 20 by placing the eye point in the eye box. Note that the eye box is defined here as an area where the entire image can be seen, but is not limited to this, and is an area where the image displayed by the HUD device 20 is viewed in a desired state, such as an area where the distortion of the image displayed by the HUD device 20 viewed by the viewer falls within a predetermined threshold value. The image (virtual image) is viewed in the virtual image display area 100 forward (Z-axis positive direction) of the windshield 2 (one example of a projection target). This allows the driver 4 to view an image (virtual image) superimposed on a foreground 300 , which is a real space viewed through the front windshield 2 .

The vehicle display system 10 (HUD device 20) of this embodiment forms the virtual image display area 100 to follow the road surface 310 (an example of the foreground 300). Specifically, the virtual image display area 100 that follows the road surface 310 indicates that the distance 100Z in the depth direction (Z-axis direction) between the far end 110 and the near end 120 of the virtual image display area 100 is 20 times or longer than the distance 100Y in the height direction (Y-axis direction) between the highest position (the far end 110 in FIG. 1) and the lowest position (the near end 120 in FIG. 1) of the virtual image display area 100, and more preferably, the distance 100Z in the depth direction (Z-axis direction) is 40 times or longer than the distance 100Y in the height direction (Y-axis direction). In the virtual image display area 100 of one embodiment, if the virtual image display area 100 is expressed by (Z coordinate [meter], Y coordinate [meter]), and the center of the height direction of the eye box is (0, 1.2), the near end 120 is (14.5, 0.0), the far end 110 (highest position) is (53.4, 1.48), and the center between the far end 110 and the near end 120 when the driver 4 sees from the center of the eye box is (27.3, 0.15). In this case, the distance 100Z in the depth direction (Z axis direction) is 38.9 [meter], and the distance 100Y in the height direction (Y axis direction) is 1.48 [meter], and the distance 100Z in the depth direction (Z axis direction) is 26 times the distance 100Y in the height direction (Y axis direction). The virtual image display area 100 is a curved surface or a partially curved surface area on which an image generated inside the HUD device 20 is formed as a virtual image, and is also called an imaging surface. The virtual image display area 100 is a position where a virtual image of a display surface (screen 24) of the HUD device 20, which will be described later, is formed, i.e., it can be said that the virtual image display area 100 corresponds to a display surface of the HUD device 20, which will be described later, and the virtual image viewed in the virtual image display area 100 corresponds to an image displayed on the display surface of the HUD device 20, which will be described later. It is preferable that the virtual image display area 100 itself has low visibility to the extent that it is not actually viewed by the driver 4 or is difficult to view.

Figure 2 is a diagram showing the configuration of the HUD device 20 of this embodiment. The HUD device 20 includes a display 21 having a display surface for displaying an image, and a relay optical system 25.

The display 21 in FIG. 2 is a projection-type display that includes a projector 22 (an example of an image generating unit) and a screen 24 (an example of a display surface) that receives projected light from the projector 22 and displays an image (real image). The display 21 may be a transmissive display (an example of an image generating unit) that transmits light from a backlight such as an LCD, or may be a self-luminous display (an example of an image generating unit). In these cases, the display surface is the display surface (an example of a display surface) in a transmissive display, and the screen 24 (an example of a display surface) in a projection-type display. The display surface is arranged at an angle that is perpendicular to the optical axis 40p of the image light 40 that travels from the display surface to the eye box (the center of the eye box) via the relay optical system 25 described below and the projected portion, thereby allowing the virtual image display area 100 to be arranged along the road surface 310. The display 21 may be equipped with an actuator (not shown) such as a motor controlled by the display control device 30, and may be capable of moving and/or rotating the display surface.

The display surface 24 of this embodiment is non-planar and has a boundary (display surface bend IM5 described later) where the continuity of the plane or curved surface is lost (bended), thereby causing the distant virtual image region 151 on the distant side of the virtual image display region 100 to be raised higher than the near virtual image region 153 on the near side of the distant virtual image region 151 of the virtual image display region 100. This will be described in detail later.

The relay optical system 25 is disposed on the optical path of the light of the image from the display 21 (light traveling from the display 21 to the eyebox) between the display 21 and the windshield 2 (an example of a projected portion), and is composed of one or more optical components that project the light of the image from the display 21 onto the windshield 2 outside the HUD device 20. The relay optical system 25 in FIG. 2 includes a first mirror 26 and a second mirror 28.

The first mirror 26 has a concave free-form surface shape with a generally constant radius of curvature from one end to the other end. In other words, the first mirror 26 has a curved surface shape with generally the same optical power for each region, that is, the optical power added to the image light 40 is the same depending on the region (optical path) through which the image light 40 passes. Specifically, the optical power added by the relay optical system 25 is generally the same for the first image light 41, the second image light 42, and the third image light 43 (see FIG. 2) traveling from each region of the display surface toward the eye box.

The second mirror 28 is a flat mirror, but is not limited to this and may be a curved surface having optical power instead of a flat surface.

In addition, the relay optical system 25 may be configured by combining multiple mirrors with curved shapes each having a different optical power for each region, and the optical power of each region of the multiple mirrors may be set so that the optical power added depending on the region (optical path) through which the image light 40 passes is approximately the same.

In this embodiment, the relay optical system 25 includes two mirrors, but is not limited to this and may additionally or instead include one or more refractive optical elements such as lenses, diffractive optical elements such as holograms, reflective optical elements, or combinations of these.

In addition, the relay optical system 25 of this embodiment has the function of setting the distance to the position where the virtual image is formed (virtual image display area 100) by using this curved shape (an example of optical power), and the function of generating a virtual image that is an enlarged image displayed on the screen 24 (display surface), but in addition to this, it may also have the function of suppressing (correcting) distortion of the virtual image that may occur due to the curved shape of the front windshield 2.

The relay optical system 25 may also be fitted with an actuator (not shown) such as a motor controlled by the display control device 30, making it movable and/or rotatable.

Next, the arrangement of the relay optical system 25 and the non-planar display surface 24, and the arrangement of the generated virtual image display area 100 according to this embodiment will be described. The virtual image display area 100 according to this embodiment is formed along the road surface 310 with an upward slope on the far side.

First, a comparative example will be described with reference to Figures 3A and 3B. Figure 3A is a diagram showing the arrangement of the relay optical system 500 and the display surface 524 of the comparative example. In Figure 3A, in order to make it easier to understand the difference from this embodiment, the focal points of each region 501, 502, and 503 of the relay optical system 500 are denoted by symbols 501f, 502f, and 503f, but the distance relationship between these focal points 501f, 502f, and 503f and the relay optical system 500, and the distance relationship between the focal points 501f, 502f, and 503f and the display surface 524 are not accurately shown. In the comparative example, the display surface 524 is a flat surface. That is, the display surface 524 of the comparative example does not have a display surface bending portion IM5 described later. Also, as in the embodiment of the present invention described next, the display surface 524 is arranged at an angle α from the perpendicular plane 524a to the optical axis 540p of the image light traveling from the display surface 524 to the eye box. Specifically, the display surface 524 is disposed at an angle α from a vertical plane 524a of an optical axis 540p of the image light 540 traveling from the display surface 524 to the eye box. Specifically, the display surface 524 is disposed so as to be gradually separated from the relay optical system 500 from a region M3 on the display surface 524 corresponding to a virtual image display vicinity 603 (FIG. 3B) of the virtual image display region 600 toward a region M2 on the display surface 524 corresponding to a region 602 (FIG. 3B) of the virtual image display region 600 that is farther away than the virtual image display vicinity 603, compared to the vertical plane 524a. In other words, the area is arranged so as to gradually approach the focal point of the relay optical system 500 from the area M3 on the display surface 524 corresponding to the virtual image display vicinity 603 of the virtual image display area 600 toward the area M2 on the display surface 524 corresponding to the area 602 (FIG. 3B) of the virtual image display area 600 farther than the virtual image display vicinity 603 (the distance between the area M2 and the focal point 502f is made shorter than the distance between the area M3 and the focal point 503f). In such a case, as shown in FIG. 3B, when viewed from the left-right direction (X direction) of the vehicle 1, the cross section of the generated virtual image display area 600 has a convex shape on the driver 4 side (upper side (positive Y-axis direction)).

Next, this embodiment will be described with reference to Figures 4A and 4B. Figure 4A is a diagram showing the arrangement of the relay optical system 25 and the display surface 24 of this embodiment. The display surface 24 of this embodiment includes a display surface far region 241 corresponding to the far virtual image region 151 and a display surface vicinity region 243 corresponding to the near virtual image region 153, and the display surface vicinity region 243 is arranged at an angle α from a perpendicular plane 24a with respect to the optical axis 40p of the image light 40 traveling from the display surface 24 to the eye box. Specifically, the display surface 24 is arranged so as to gradually move away from the relay optical system 25 from the display surface vicinity portion IM3 of the display surface 24 corresponding to the virtual image display vicinity portion 103 included in the near virtual image region 153 of the virtual image display region 100 toward the display surface bending portion IM5 of the display surface 24 corresponding to the virtual image display bending portion 105 of the virtual image display region 100, compared to the perpendicular plane 24a. In other words, the display surface 24 is arranged so as to gradually approach the focus of the relay optical system 25 from the display surface vicinity IM3 of the display surface 24 corresponding to the nearby virtual image region 153 of the virtual image display region 100 toward the display surface bend IM5 of the display surface 24 corresponding to the virtual image display bend 105 of the virtual image display region 100 (the distance between the display surface bend IM5 and the focus 255f is made shorter than the distance between the display surface vicinity IM3 and the focus 253f).

Furthermore, the display surface 24 of this embodiment has a display surface bending portion IM5, and is bent so that the approximate inclination of the display surface 24 from the display surface vicinity portion IM3 to the display surface bending portion IM5 approaches the relay optical system 25, based on the approximate inclination of the display surface 24 from the display surface vicinity portion IM3 to the display surface bending portion IM5 (the dotted line in FIG. 4A). In other words, it is arranged so as to gradually approach the focus of the relay optical system 25 from the display surface vicinity portion IM3 toward the display surface bending portion IM5 (the distance between the display surface bending portion IM5 and the focus 255f is made shorter than the distance between the display surface vicinity portion IM3 and the focus 253f), and is arranged so as to gradually approach the focus of the relay optical system 25 from the display surface bending portion IM5 toward the display surface distant portion IM1 (the distance between the display surface distant portion IM1 and the focus 251f is made longer than the distance between the display surface bending portion IM5 and the focus 255f).

Here, the following relational expression is established among the distance a (>0) between the object and the concave mirror, the distance b (>0) between the virtual image and the concave mirror, and the focal length f (>a) of the concave mirror. According to this relational expression, the shorter the distance between the object and the concave mirror, the shorter the distance b of the virtual image.
1/a-1/b=1/f

As described above, the display surface 24 is arranged at an angle from the optical axis 40p of the image light traveling from the display surface 24 to the eye box, so that the virtual image display area 100 is arranged to follow the road surface 310 (so that the imaging distance gradually increases from the vicinity to the distance). The first image light 41 projected from the display surface 24 (display surface distant area 241 (display surface distant portion IM1)) to the first area 251 of the first mirror 26 has a shorter imaging distance from the windshield 2 when reflected by the windshield 2 (compared to a case where the display surface is not bent and cannot be brought close to the relay optical system) because the display surface distant area 241 (display surface distant portion IM1) is close to the first area 251.

In the display surface 24 of this embodiment, the display surface distant region 241 bounded by the display surface bending portion IM5 is brought closer to the relay optical system 25 (reducing the distance between the object and the concave mirror) than the approximate tilt of the display surface 24 from the display surface vicinity portion IM3 to the display surface bending portion IM5 (dotted line in Figure 4A), thereby allowing the distant virtual image region 151 (including the distant end 110) of the virtual image display area 100 to be curved so as to rise up from the tilt along the road surface 310. Curving the distant virtual image region 151 (including the distant end 110) so as to rise from an inclination along the road surface 310 means that, as shown in FIG. 4B, the tilt angle θ (first tilt angle θ1) between the tangent to the virtual image display region 100 in the distant virtual image region 151 (virtual image display distant portion 101) and the road surface 310 is greater than the tilt angle θ (second tilt angle θ2) between the tangent to the virtual image display region 100 and the road surface 310 in the near virtual image region 153 (central portion 102) which is closer to the driver 4 than the distant virtual image region 151, and the tilt angle θ increases continuously (monotonically increases) from the central portion 102 (nearby side) toward the distant virtual image region 151 (far side).

5A to 5C are diagrams showing the relationship between the position in the depth direction (Z-axis direction) of the virtual image display area 100 and the tilt angle θ according to an embodiment. In this embodiment, it is sufficient that the distant virtual image area 151 (distant end 110) rises from an inclination along the road surface 310 relative to the central portion 102 near the distant virtual image area 151, and the tilt angle θ is not limited to monotonically increasing from the near end 120 toward the far end 110 as shown in FIG. 5A.

That is, in some embodiments, as shown in FIG. 5B, the increase rate (rate of change) of the tilt angle θ from the virtual image display vicinity portion 103 to the virtual image display bent portion 105 may be smaller than the increase rate (rate of change) of the tilt angle θ from the virtual image display bent portion 105 to the virtual image display distant portion 101. In this case, the display surface 24 is configured such that the increase rate from the distance between the display surface vicinity portion IM3 and the third region 253 of the relay optical system 25 through which the third image light 43 passes to the distance between the display surface bent portion IM5 and the fifth region 255 of the relay optical system 25 through which the fifth image light 45 passes is smaller than the increase rate from the distance between the display surface bent portion IM5 and the fifth region 255 of the relay optical system 25 through which the fifth image light 45 passes to the distance between the display surface distant portion IM1 and the first region 251 of the relay optical system 25 through which the first image light 41 passes. This makes it possible to suppress the change in the distance between the nearby virtual image region and the road surface as the distance in the depth direction increases.

In some embodiments, as shown in FIG. 5C, the rate of change of the tilt angle θ from the near virtual image region 153 to the central portion 102 may be gradually increased from a negative value to zero, and the rate of increase (rate of change) of the tilt angle θ from the central portion 102 to the far end 110 may be greater than zero. The arrangement of the virtual image display region 100 in this case is shown in FIG. 6. That is, the position of this virtual image display region 100 gradually decreases in the vertical direction (Y-axis direction) from the near virtual image region 153 to the central portion 102, with the central portion 102 being the lowest position, and the position gradually increases in the vertical direction (Y-axis direction) from the central portion 102 to the far end 110, with the near end 120 being the highest position. In this case, the inclination α of the display surface 24 is made larger than in the above embodiment, and the rate of increase from the distance between the display surface vicinity portion IM3 and the third region 253 of the relay optical system 25 through which the third image light 43 passes to the distance between the display surface bending portion IM5 and the fifth region 255 of the relay optical system 25 through which the fifth image light 45 passes is made smaller than the rate of increase from the distance between the display surface bending portion IM5 and the fifth region 255 of the relay optical system 25 through which the fifth image light 45 passes to the distance between the display surface distant portion IM1 and the first region 251 of the relay optical system 25 through which the first image light 41 passes. This makes it possible to keep small the change in the distance between the near-side virtual image display region and the road surface that follows an increase in the distance in the depth direction.

In some embodiments, a part of the virtual image display area 100 including the lowest position may be placed below the road surface 310, and a part of the virtual image display area 100 including the far end 110 may be placed above the road surface. For example, as shown in FIG. 7A, the near end 120 of the virtual image display area 100 may be placed below the road surface 310 from the near end 120 to the far end 110, and the other part from this to the far end 110 may be placed above the road surface 310. Also, as shown in FIG. 7B, the virtual image display area 100 may have the center part 102 between the far end 110 and the near end 120 as the lowest position. The discomfort felt by the viewer when the virtual image is displayed shifted toward the front side relative to the road surface is greater than the discomfort felt when the image is displayed shifted toward the back side relative to the road surface. Therefore, even if the angle of the vehicle 1 changes, it is possible to prevent the virtual image display area 100 from being positioned above the road surface 310, and even if the angle of the vehicle 1 changes so that the near-side virtual image display area is positioned above the road surface 310, the vertical distance between the near-side image and the road surface 310 can be kept small.

In addition, in some embodiments, the position of the display surface bend IM5 of the display surface 24 may be set so that the virtual image display bend 105 of the virtual image display area 100 is located 20 meters or more in the forward direction of the driver 4 (vehicle 1). According to this, as the virtual image display area 100 moves from a distance of 20 meters or more in the forward direction of the vehicle 1 toward the far side, the tilt angle θ of the tangent of the virtual image display area 100 to the forward/rearward direction of the vehicle 1 increases monotonically, and rises from an angle along the road surface 310. The inventor of the present invention recognized that the sense of distance (perception of distance) for objects 20 meters or more away from the viewer becomes dull. That is, even if the distance between the virtual image display area and the road surface is monotonically increased from a position 20 meters or more away from the viewer, the viewer is unlikely to perceive the difference in distance between the virtual image display surface and the road surface (it is easy to perceive that the image is displayed along the road surface like the image displayed in the virtual image display area less than 20 meters away), and by curving the virtual image display area on the far side so that it rises up toward the viewer from an angle along the road surface, the virtual image display surface on the far side as seen by the viewer can be superimposed on a wide foreground (for example, the road surface). In other words, the area of the foreground (for example, the road surface) that overlaps per unit area of the virtual image display area can be expanded, and an image can be efficiently superimposed and displayed on the wide foreground.

In the above embodiment, the first mirror 26 has a free-form surface shape with a generally constant radius of curvature from one end to the other end, but this is not limited to this, and the curvature does not have to be generally constant. In particular, in this embodiment, the display surface bending portion IM5 is provided on the display surface 24 to make the inclination of the far side of the virtual image display area 100 rise from an angle that follows the road surface. In addition, the radius of curvature (optical power) may be made different for each area of the first mirror 26 (relay optical system 25) to make it easier for the inclination of the far side of the virtual image display area 100 to rise from an angle that follows the road surface.

Specifically, the first mirror 26 may have a free-form surface shape in which the radius of curvature gradually changes from one end to the other end. In other words, the first mirror 26 may have a curved surface shape in which the optical power differs for each region, that is, the optical power added to the image light 40 may differ depending on the region (optical path) through which the image light 40 passes. Specifically, the optical power added by the relay optical system 25 differs between the first image light 41, the second image light 42, and the third image light 43 (see FIG. 2) traveling from each region of the display surface toward the eye box.

The second mirror 28 may be a curved surface having optical power instead of a flat surface. In other words, the relay optical system 25 may combine multiple mirrors (e.g., the first mirror 26 and the second mirror 28 in this embodiment) to add different optical power depending on the area (optical path) through which the image light 40 passes.

Figure 8 is a diagram showing the arrangement of the relay optical system 25 and the display surface 24 of this embodiment. In FIG. 8, the foci of each region 251, 252, 253 of the relay optical system 25 are denoted by symbols 251f, 252f, 253f in order to make it easier to understand the difference from the comparative example, but the distance relationship with the relay optical system 25 or the display surface 24 is not accurately shown. The relay optical system 25 in FIG. 8 has a different radius of curvature for each region. Specifically, the first optical power of the first region (first optical path) 251 of the relay optical system 25 through which the first image light 41 that displays a virtual image in the distant virtual image region 151 of the virtual image display region 100 as seen from the driver 4 passes is made smaller than the second optical power of the second region (second optical path) 252 of the relay optical system 25 through which the second image light 42 that displays a virtual image in the virtual image display bend portion 105 closer to the driver 4 than the distant virtual image region 151 of the virtual image display region 100 passes. That is, when the main optical power of the relay optical system 25 is due to the first mirror 26 which is a concave mirror, the first radius of curvature (an example of the first optical power) of the first region 251 which reflects the first image light 41 is made larger than the second radius of curvature (an example of the second optical power) of the second region 252 which reflects the second image light 42. When the first radius of curvature of the first region 251 which reflects the first image light 41 is larger, the focal length (1/2 the radius of curvature) of the focal point 251f of the first region 251 becomes longer.

According to the above-mentioned relationship "1/a - 1/b = 1/f," the larger the radius of curvature of the concave mirror (the smaller the mirror curvature), the longer the focal length of the concave mirror, and the longer the focal length, the shorter the distance b of the virtual image.

The display surface 24 is arranged at an angle from the optical axis 40p of the image light traveling from the display surface 24 to the eye box, so that the virtual image display area 100 is arranged so as to follow the road surface 310 (so that the imaging distance gradually increases from the vicinity to the distance). The first image light 41 projected from the display surface 24 to the first area 251 having a large radius of curvature of the first mirror 26 has a long focal length (the distance from the first area 251 to the focal point 251f) and therefore, when reflected by the windshield 2, the imaging distance from the windshield 2 is shortened (compared to the case where the radius of curvature is not large).

In the relay optical system 25 of this embodiment, the optical power is gradually decreased (the radius of curvature is gradually increased) as the virtual image displayed by the passing image light becomes farther away, so that the far virtual image region 151 (far end 110) of the virtual image display region 100 can be curved so as to rise from the inclination along the road surface 310. Therefore, by combining bending the display surface 24 so that the far virtual image region of the virtual image display surface rises from the road surface, and similarly varying the optical power of the relay optical system 25 for each region so that the far virtual image region of the virtual image display surface rises from the road surface, it is possible to curve the virtual image display surface more greatly, and it is also possible to improve the design freedom of the display surface 24 and the relay optical system 25.

The display surface distant portion IM1 corresponding to the distant virtual image region 151 and the display surface nearby portion IM3 corresponding to the near virtual image region 153 are discontinuously connected. That is, the display surface 24 is formed such that the display surface distant portion IM1 is connected to the display surface nearby portion IM3 not by a smooth curved surface but by a discontinuous display surface bend portion IM5.

1: Vehicle 2: Front windshield 4: Driver 5: Dashboard 10: Vehicle display system 20: HUD device 21: Display 22: Projector 24: Screen (display surface)
25: Relay optical system 26: First mirror 28: Second mirror 30: Display control device 40: Image light 40p: Optical axis 41: First image light 42: Second image light 43: Third image light 45: Fifth image light 100: Virtual image display area 101: Virtual image display distant part 102: Central part 103: Virtual image display nearby part 105: Virtual image display bent part 110: Distant end 120: Near end 151: Distant virtual image area 153: Near virtual image area 241: Display surface distant area 243: Display surface nearby area 251: First area 252: Second area 253: Third area 255: Fifth area 310: Road surface IM1: Display surface distant part IM3: Display surface nearby part IM5: Display surface bent part α: Angle θ: Tilt angle θ1 : First tilt angle θ2 : Second tilt angle

Claims (9)

A head-up display device that allows a viewer to view a virtual image in a virtual image display area along a front-rear direction of a vehicle,
a display having a display surface that emits image light that is the source of the virtual image;
a relay optical system configured to relay the image light emitted by the display surface toward a projection target,
the virtual image display area is composed of a distant virtual image area and a nearby virtual image area that is closer to the viewer than the distant virtual image area,
The display surface is
a display surface distant region corresponding to the distant virtual image region and a display surface near region corresponding to the near virtual image region,
the display surface vicinity region is disposed at an angle with respect to an optical axis of the image light directed toward the viewer so that the vicinity virtual image region is disposed along a front-rear direction of the vehicle,
The display surface distant region is disposed so as to be bent with respect to the display surface near region such that the distant virtual image region rises toward the viewer side with respect to the near virtual image region.
Head-up display device. The display surface distant region is formed so as to be connected to the display surface near region by a discontinuous display surface bend portion,
the display device is configured such that the display surface bending portion is disposed such that the virtual image display bending portion of the virtual image display area corresponding to the display surface bending portion is disposed at a distance of 20 meters or more in a forward direction of the viewer;
The head-up display device according to claim 1 , the display device is configured such that the relay optical system side is formed into a concave curved surface so as to suppress a convex curve of an upper side of the near virtual image area caused by the display surface near area being disposed at an angle with respect to an optical axis of the image light directed toward the viewer;
The head-up display device according to claim 1 , The display surface distant region is formed so as to be connected to the display surface near region by a discontinuous display surface bend portion,
a first region having a first optical power through which a first image light for displaying the virtual image passes in a virtual image display distant portion of the distant virtual image region ;
a fifth region having a fifth optical power through which a fifth image light for displaying the virtual image passes at a virtual image display bending portion of the virtual image display region corresponding to the display surface bending portion ,
a relay optics configured such that the first optical power is less than the fifth optical power;
The head-up display device according to claim 1 , a third region having a third optical power through which a third image light for displaying the virtual image passes in a virtual image display vicinity portion closer to the virtual image display bend portion as viewed by the viewer,
the relay optical system configured such that a rate of change of optical power from the fifth region to the first region is greater than a rate of change of optical power from the third region to the fifth region;
The head-up display device according to claim 4 , the relay optical system adjusts the distribution of optical power of the first region, the fifth region, and a region therebetween so that an angle of a tangent of the virtual image display region with respect to a longitudinal direction of the vehicle increases monotonically in a broad sense from the vicinity of the viewer to the distant position;
The head-up display device according to claim 4 , the virtual image display bend portion is located between a far end and a near end of the virtual image display area as seen by the viewer in the front-rear direction of the vehicle, and is disposed at a lowest position of the virtual image display area.
The head-up display device according to claim 4. a portion of the virtual image display area is disposed below a road surface, and another portion including the virtual image display distant portion is disposed above the road surface;
The head-up display device according to claim 4. a portion of the virtual image display region including the virtual image display bent portion is disposed below a road surface, and another portion of the virtual image display region including the virtual image display distant portion is disposed above the road surface;
The head-up display device according to claim 8.

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