WO2022024964A1

WO2022024964A1 - Head-up display device

Info

Publication number: WO2022024964A1
Application number: PCT/JP2021/027463
Authority: WO
Inventors: 勇希舛屋
Original assignee: 日本精機株式会社
Priority date: 2020-07-29
Filing date: 2021-07-26
Publication date: 2022-02-03
Also published as: CN116157290A; DE112021004005T5; JPWO2022024964A1

Abstract

The purpose of the present invention is to make it possible to display, in an oblique image surface HUD device, an image (erect image) of a content to be viewed in an erect position while suppressing a decrease in visibility.　A control unit of a head-up display device according to the present invention performs control for displaying an erect image that is an image to be viewed in an erect position within a display area (Z1) that is a flat or curved inclined plane inclined from a side that is close to a viewer and a lower side to a side that is far from the viewer and an upper side with respect to a ground surface or a plane (40) corresponding to the ground surface in real space, the erect image is displayed in the display area (Z1) that is a quadrangular outline when viewed from the viewer, a convergence angle difference (θL-θU) between an upper end (PU) and a lower end (PL) of the display area (Z1) is set to less than a predetermined threshold (preferably a convergence angle of 0.2°) determined on the basis of at least one of the visibility of the image, the time required for visual recognition, and a psychological factor such as an uncomfortable feeling or an unpleasant feeling.

Description

Head-up display device

The present invention is, for example, a head-up display (HUD) that projects (projects) image display light onto a windshield such as a vehicle or a projected member such as a combiner to display a virtual image in front of the driver. ) Regarding equipment, etc.

For the purpose of improving the information recognition of the viewer (driver, etc.), it has been proposed to incline the virtual image display surface of the HUD device in the depth direction (see, for example, Patent Document 1).

In this type of HUD device (hereinafter, may be referred to as an oblique image surface HUD device or an inclined surface HUD device), cognition is improved by presenting an information image (depth image such as an arrow or a map) having depth information. At the same time, it is also possible to make an information image (upright image such as text or numbers) having no depth information (in a broad sense, not emphasizing depth) stand upright and visually recognized, which is highly convenient.

In addition, "upright" in the case of making it stand upright is used in the following meanings, for example. For example, if the content (content) represented by letters or numbers is upside down and inverted, or if the display surface is tilted to a large extent, can a person see (recognize) it? Or, it becomes difficult to see.

Therefore, when displaying characters, numbers, etc., the HUD device needs to display it as correctly upright content so that a person can read the information correctly. The above image (virtual image) is called an upright image (upright virtual image). Since the upright image is often displayed so that the viewer faces each other, it may be said that the image is a facing image.

Japanese Unexamined Patent Publication No. 2018-120135

The present inventor examined the oblique image plane HUD device and recognized the following new problems. If an image (virtual image) can be displayed on an inclined surface, as described above, an image (virtual image) with a sense of depth can be displayed, and the inclination is to some extent the ground (or a surface corresponding to the ground: equivalent). If it is erected on the surface), it can be displayed as an upright image of the content whose constituent elements are characters, numbers, and the like, for which a sense of depth is not emphasized.

However, if the inclined surface is greatly inclined with respect to the ground (corresponding surface thereof), it will be in a state suitable for a deep display, but on the other hand, there will be a problem such as deterioration of visibility for an upright image. As a result, there are problems such as difficulty in recognition by the viewer, long time required for recognition even if it can be recognized, or subjective discomfort or discomfort.

If these problems do not become apparent, it means that the upright image can be recognized correctly, in other words, the upright image can be visually recognized. If not, the upright image can be discriminated, identified, visually recognized, etc. It means that it cannot be done or it is difficult to see.

Therefore, in order to appropriately perform efficient design of the HUD device, calibration of the HUD device, initialization of the HUD device, etc., it is determined whether or not a normal upright image can be recognized. It is preferable to provide a reference index.

For example, when displaying an image (virtual image) at a position several meters ahead of a predetermined point of a vehicle or the viewpoint of a viewer (driver, etc.), what is the inclination angle of the display area with respect to the ground (equivalent surface)? It is conceivable to set restrictions such as not to be less than the degree.

However, the visibility (visual sensitivity) of a person depends on the distance to the image, and the sensitivity is high when displayed on the front side and relatively low when displayed on the back side. With such a setting method, if the distance changes, the inclination (inclination angle) also changes, and a unified standard (threshold value) cannot be obtained, which is not easy to use.

Therefore, it is important to obtain an index that serves as a standard (threshold value) that can be used in a unified manner, and to appropriately set a preferable value of the threshold value. Once this index is obtained, it is possible to set the slope of the inclined surface (or display area) so that the reading of the upright image is not hindered by using the index, and the design and the like can be facilitated. In the prior art such as Patent Document 1, no study has been made on this point, and an appropriate index has not been obtained.

One of the objects of the present invention is to enable an oblique image plane HUD device to display an image of content (upright image) to be viewed upright while suppressing a decrease in visibility.

Other objects of the invention will be apparent to those skilled in the art by reference to the embodiments exemplified below and the best embodiments, as well as the accompanying drawings.

Hereinafter, in order to easily understand the outline of the present invention, an embodiment according to the present invention will be illustrated.

In the first aspect, the head-up display device is
An image display unit that displays an image and
By projecting the light of the image displayed by the image display unit toward the projected member, the viewer can visually recognize the virtual image of the image within a virtual display area in the real space in front of the viewer. Optical system and
A control unit that controls the display of the image in the image display unit,
Have,
The direction toward the front of the viewer in the real space is defined as the forward direction.
The direction perpendicular to the front direction and along the line segment connecting the left and right eyes of the viewer is defined as the left-right direction.
The direction along the line segment orthogonal to the front direction and the left-right direction is defined as the vertical direction or the height direction.
When the direction away from the ground or the surface corresponding to the ground in the real space is the upward direction, and the direction toward the ground is the downward direction.
The control unit
In the display area, which is an inclined surface of a flat surface or a curved surface that inclines from the side close to the viewer and the lower side to the far side and the upper side with respect to the ground or a surface corresponding to the ground in the real space. In addition, control is performed to display an upright image, which is an upright image to be visually recognized.
The upright image is displayed in a display area that is the outline of a quadrangle when viewed from the viewer.
The difference in convergence angle between the upper end and the lower end of the display area is set to be less than a predetermined threshold value determined based on at least one of the visibility of the image, the time required for visual recognition, and psychological factors such as discomfort and discomfort. ..

In the first aspect, the degree of inclination of the display area so that the upright image can be correctly visually recognized is replaced by "convergence angle difference (provided that the inclination distortion angle caused by the difference (see the angle θd in FIG. 6C)). It is possible to make a judgment using a new index (standard as a threshold value), which makes it more efficient (or easier) to determine and set the degree of inclination.

It is assumed that the display area has a quadrangular outline, the ground (or equivalent surface of the ground: road surface, etc.) side of the display area is the lower end (lower side), and the opposite side (the side away from the ground) is the upper end (upper side). do. Here, for example, a pair of points (which can be provided at arbitrary positions) corresponding to each other at each of the lower end (lower side) and the upper end (upper side) are preferably provided, for example, the right end point or the left end point of each end (each side). ) Is set. This pair of points is defined as a first point and a second point, and the convergence angle (the angle formed by the visual axis indicating the line-of-sight direction of each eye) when the first point is viewed from each of the left and right eyes is the first point. The convergence angle is defined as the convergence angle when the second point is viewed, and the difference between the first congestion angle and the second convergence angle (the first congestion angle to the second convergence angle is defined as the second convergence angle). The subtracted difference) is defined as the "convergence angle difference". In other words, this convergence angle difference can be said to be "convergence angle difference between the upper end and the lower end of the display area".

Here, if the display area is erected on the ground (corresponding surface thereof) at a substantially right angle, for example, the upper end (upper side) and the lower end (lower side) of the quadrangle are viewed in a plan view from above. ) Overlap, and the first point and the second point overlap. Assuming that the length (height) of the vertical side of the quadrangle is small, the variation in the distance between the first and second points and the left and right eyes due to the height position of each of the first and second points. Can be ignored. In the above case, the first and second convergence angles for each of the first and second points are the same (substantially the same), and the convergence angle difference is zero (substantially zero).

Here, when the display area is tilted with respect to the ground (corresponding surface thereof) and the lower end (lower side) of the quadrangle moves toward the viewer, there is a difference in the value of the convergence angle at each of the first and second points. .. In other words, the first convergence angle is larger than the second convergence angle. Therefore, the convergence angle difference is α (α is an integer larger than 0).

When the display area is further inclined and the lower end (lower side) of the quadrangle moves further toward the viewer and approaches the viewer, the first convergence angle further increases, so that the difference from the second convergence angle is. It becomes large and the convergence angle difference becomes β (β is an integer satisfying α <β).

In this way, the "convergence angle difference between the upper end and the lower end of the display area" is an index indicating the degree of inclination of the display area with respect to the ground (corresponding surface thereof). Further, since the convergence angle fluctuates depending on the distance from the viewer's eyes, distance information is included. Therefore, the convergence angle difference is the ground of the display area (or the virtual image display surface, etc.) including the distance. It is one integrated index (threshold value) that has information on the degree of inclination with respect to (its equivalent surface). Unlike the conventional method, it is not necessary to set the inclination with the precondition such as the number of inclination angles at a distance of several meters.

Here, the visibility of an upright image varies from person to person and cannot be unequivocally stated, but it is based on at least one of the visibility of the image to be displayed, the time required for viewing, and psychological factors such as discomfort and discomfort. It is possible to objectively determine whether or not a normal upright image can be visually recognized. Then, by using the above index in the determination, a threshold value that can be used in the determination can be obtained.

As described above, the larger the inclination of the display area and the closer the first point is to the viewer, the larger the value of the convergence angle difference becomes. Therefore, for example, the difference in convergence angle near the limit at which the viewer can fuse (synthesize) each image of the left eye and the right eye in the brain to recognize the erect image is set as a threshold value, and for example, when designing a HUD device. If each part is set so that the difference in convergence angle is less than the threshold value, the viewer can recognize the upright image even if it is displayed on the inclined surface. In other words, the visibility of the upright image by the viewer is ensured to a predetermined level or higher.

In this way, for example, a design that enables an image of content (upright image) to be visually recognized upright while suppressing a decrease in visibility is streamlined or facilitated. In addition, this new index (convergence angle difference or tilt distortion angle caused by this) can also be used for calibration of the HUD device, initialization of the HUD device, simulation of the function of the HUD device, and the like. , The effect of improving the efficiency of each process can be obtained.

In the second aspect, which is subordinate to the first aspect,
The display area includes a first area in which both a virtual image of a depth image, which is an image to be visually recognized by being tilted, and a virtual image of the upright image can be displayed, and a second area for displaying a virtual image of the depth image. Divided into
The convergence angle difference between the upper end and the lower end of the display area in the first region is set to be less than the predetermined threshold value, and the convergence angle difference between the upper end and the lower end of the display area in the second region is set to be equal to or higher than the predetermined threshold value. It may have been done.

In the second aspect, the display area is divided into a first area capable of displaying both a depth image and an upright image and a second area suitable for displaying a depth image, and the display in the second area is performed. The difference in convergence angle between the upper end and the lower end of the region is set to be equal to or higher than the above-mentioned predetermined threshold value.

As described above, the threshold value is set based on the visibility of the upright image and the like, and above the threshold value, the visibility of the upright image is lowered and it is not suitable for displaying the upright image. In other words, it is suitable for displaying a depth image expressed in an inclined manner (including an image that floats in the air and extends substantially parallel to the road surface, etc., or gives a visual sense superimposed on the road surface). It can be said that. Therefore, for the image (virtual image) displayed in the second region, the convergence angle difference or the like is set to be equal to or higher than the threshold value. Thereby, for example, when an upright image is displayed in the first region and a depth image is displayed in the second region, appropriate visibility of each image can be ensured.

In the third aspect, which is subordinate to the first or second aspect,
The predetermined threshold value functions as a normal visibility determination threshold for determining the normal visibility of the upright image.
The convergence angle difference as the predetermined threshold value may be set to 0.2 °.

In the third aspect, it is clarified that the above-mentioned "predetermined threshold value" can be specifically used as, for example, a "normal visibility determination threshold value", and an example of a preferable value thereof is 0.2 °. It clarifies that there is.

In the fourth aspect, which is subordinate to any one of the first to the third.
When the angle of view in the vertical direction (or height direction) seen from the viewer is referred to as a vertical angle of view, the limitation of the convergence angle difference by the predetermined threshold is the content of an upright image having a vertical angle of view of 0.75 ° or less. May be applied to.

In the fourth aspect, a vertical image is taken into consideration that as the size of the displayed content increases, it becomes more difficult to fuse the image of the left eye and the image of the right eye in the brain even with the same convergence angle difference. The above threshold value is applied to small contents having an angle of 0.75 ° or less, and the difference in convergence angle between the upper end and the lower end is set to be less than the threshold value.

In addition, it has been confirmed that upright content larger than this size is more annoying from the viewpoint of visibility obstruction in the HUD device, and it cannot be said that the current feasibility is high. Therefore, it is considered that there is no particular problem even if the above threshold value is applied only to the display contents having a predetermined size or less.

Those skilled in the art will easily understand that the embodiments according to the present invention may be further modified without departing from the spirit of the present invention.

FIG. 1A is a diagram showing an example of a configuration of a HUD device mounted on a vehicle and an inclined display area, and FIGS. 1B and 1C are display areas shown in FIG. 1A. It is a figure which shows the example of the method to realize. FIG. 2A is a diagram showing a main configuration of a HUD device mounted on a vehicle and a display example in a display area, and FIG. 2B is a diagram showing both a virtual image of a depth image and a virtual image of an upright image. It is a figure which shows the example of the display area | region which is composed of the 1st possible area and the 2nd area which displays a virtual image of a depth image. FIG. 3A is a diagram and a diagram showing a state in which an inclined surface (inclined display area) on which an arrow figure as a depth image is displayed is arranged in front and the viewer is viewing it with both eyes. 3 (B) is a diagram showing an image seen with the left eye, and FIG. 3 (C) is a diagram showing a depth image seen by fusing (combining) each image of the left eye and the right eye, FIG. 3 (C). D) is a diagram showing an image seen by the right eye. FIG. 4A is a diagram showing a state in which an inclined surface (inclined display area) on which a vehicle speed display as an upright image is displayed is arranged in front and the viewer is viewing it with both eyes. 4 (B) is a diagram showing an image seen with the left eye, and FIG. 4 (C) is a diagram showing an upright image seen by fusing (combining) each image of the left eye and the right eye, FIG. 4 (D) is a figure showing an image seen by the right eye. FIG. 5 (A) is a diagram showing a state in which a viewer is viewing a display area erected substantially perpendicular to the road surface with both eyes, and FIG. 5 (B) is a view of the display area in FIG. 5 (A). A diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 5C is a diagram showing the left eye. It is a figure which shows the image which fused (combined) each image of a right eye. FIG. 6A is a diagram showing a state in which a viewer is viewing a display area inclined by approximately 45 ° with respect to the road surface with both eyes, and FIG. 6B is a display area in FIG. 6A. A diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 6C is a diagram showing the left eye. FIG. 6 (D) is a diagram showing an upright image obtained by fusing (synthesizing) each image of the left eye and the right eye, and FIG. 6 (E) is a diagram showing an image viewed with the right eye. It is a figure which shows. FIG. 7A is a diagram showing a state in which a viewer is viewing a display area inclined by approximately 30 ° with respect to the road surface with both eyes, and FIG. 7B is a display area in FIG. 7A. FIG. 7 (C) is a diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 7 (C) is the left eye. FIG. 7 (D) is a diagram showing the images seen in the above, and FIG. 7 (D) is a diagram showing visual perception that is difficult to see due to double vision when each image of the left eye and the right eye is fused (combined). , Is a diagram showing an image seen with the right eye. 8 (A) and 8 (B) are flowcharts showing an example of a design method of a HUD device (oblique image plane HUD device). It is a figure which shows the structural example of the display control unit (control unit) in a HUD apparatus. 10 (A) and 10 (B) are views showing another example of the inclined display area. FIG. 11 is a graph of experimental results showing the proportion (vertical axis) of those who answered that they did not feel uncomfortable with each convergence angle difference (horizontal axis).

The best embodiments described below are used for easy understanding of the present invention. Accordingly, one of ordinary skill in the art should note that the invention is not unreasonably limited by the embodiments described below.

Refer to FIG. FIG. 1A is a diagram showing an example of a configuration of a HUD device mounted on a vehicle and an inclined display area, and FIGS. 1B and 1C are display areas shown in FIG. 1A. It is a figure which shows the example of the method to realize. In FIG. 1, the direction along the front of the vehicle 1 (also referred to as the front-rear direction) is the Z direction, the direction along the width (horizontal width) of the vehicle 1 is the X direction, and the height direction or the upper side of the vehicle 1. Direction (Y direction is the direction away from the ground or its corresponding surface (here, the road surface) 40 of the line segment perpendicular to the flat road surface 40.

Further, in the following description, the term virtual display area (sometimes simply referred to as a display area) provided in front of the viewer can be broadly interpreted. For example, it may be a virtual display surface (sometimes referred to as a virtual image display surface) corresponding to (the display range of) a display surface such as a screen on which an image is displayed, or it may be displayed on the virtual display surface. When one image to be created is arranged in an image area having a predetermined shape (for example, a quadrangle) having a predetermined size, the image area can be regarded as one display area (or a part of a virtual image display surface). .. In the following description, based on the above, it is simply referred to as "display area".

In addition, in the explanation of the shape of the display area, the expressions "upper" and "lower" may be used. Here, for convenience of explanation, the direction along the line segment (normal line) perpendicular to the road surface 40 (which is also the height direction of the vehicle 1) is taken as the vertical direction. When the road surface is horizontal, the vertical downward direction is downward and the opposite direction is upward. This point may also apply to the description of other drawings.

As shown in FIG. 1A, the HUD device 100 of this embodiment is mounted inside the dashboard 41 of the vehicle (own vehicle) 1. The HUD device 100 is an upright image (an image that does not particularly emphasize depth and is also referred to as an erect image) in which the display area PS1 having an area inclined with respect to the road surface 40 is visually recognized in an upright position in front of the vehicle 1. (For example, it may be composed of numbers, letters, etc.), and a depth image in which depth is an important factor (also referred to as an inclined image or an inclined image, for example, a navigation arrow extending along the road surface 40). Etc.) can be displayed.

The HUD device 100 has a display unit (sometimes referred to as an image display unit, specifically, a screen) 160 having a display surface 164 for displaying an image, and a display light K for displaying an image, and a projected member (reflection). A curved mirror (concave mirror) having an optical system 120 including an optical member projecting onto a windshield which is a translucent member) 2 and a light projecting unit (image projection unit) 150, and the optical member 120 has a reflecting surface 179. The reflecting surface 179 of the curved mirror 170 having 170 (also referred to as a magnifying mirror) is not a shape having a uniform radius of curvature, but a shape consisting of, for example, a set of partial regions having a plurality of radius of curvature. For example, a free curved surface design method can be used (the free curved surface itself may be used). A free curved surface is a curved surface that cannot be expressed by a simple mathematical formula, and a curved surface is expressed by setting some intersections and curvatures in space and interpolating each intersection with a higher-order equation. The shape of the reflective surface 179 has a considerable influence on the shape of the display area PS1 and the relationship with the road surface.

The shape of the display area PS1 includes the shape of the reflective surface 179 of the curved mirror (concave mirror) 130, the curved shape of the windshield (reflection translucent member 2), and other optical members mounted in the optical system 120. It is also affected by the shape of (for example, the correction mirror). It is also affected by the shape of the display surface 164 of the display unit 160 (generally a flat surface, but all or part of it may be non-planar) and the arrangement of the display surface 164 with respect to the reflective surface 179. However, the curved mirror (concave mirror) 170 is a magnifying reflector, and has a considerable influence on the shape of the display area (virtual image display surface). Further, if the shape of the reflecting surface 179 of the curved mirror (concave mirror) 170 is different, the shape of the display area (virtual image display surface) PS1 actually changes.

Further, in the display area PS1 integrally extending from the near end portion U1 to the far end portion U3, the display surface 164 of the display unit 160 is 90 with respect to the optical axis of the optical system (the main optical axis corresponding to the main light ray). It can be formed by arranging diagonally at an intersection angle of less than a degree.

Further, the shape of the curved surface of the display area PS1 is such that the optical characteristics of all or a part of the optical system can be adjusted, the arrangement of the optical member and the display surface 164 can be adjusted, and the shape of the display surface 164 can be adjusted. It may be adjusted or adjusted by a combination thereof. In this way, the shape of the virtual image display surface can be adjusted in various ways. Thereby, the display area PS1 having the first area Z1 and the second area Z2 can be realized.

In other words, the display area PS1 is suitable for displaying the first area Z1 capable of displaying both the depth image (tilted image) and the upright image (standing image) and the depth image (tilted image) (in other words, the depth image). It is divided into a second area (used exclusively for display of).

Hereafter, this point will be explained concretely. As shown on the left side and the lower left side of FIG. 1B, the mode and degree of the overall inclination of the display area (including the virtual image display surface) PS1 are adjusted according to the mode and degree of inclination of the display surface 164 of the display unit 160. do. In the example of FIG. 1B, the distortion of the display area (virtual image display surface) due to the curved surface of the windshield (reflection and translucent member 2) is corrected by the curved surface shape of the reflective surface 179 of the curved mirror (concave mirror or the like) 170. As a result, a flat display area (virtual image display surface) PS1 is generated.

Further, as shown on the right side and the lower left side of FIG. 1B, by adjusting the positional relationship between the optical member (here, the curved surface mirror (concave mirror or the like) 170) and the display surface 164, in other words, the display surface 164 is rotated. By moving the mirror to make the relative relationship with the optical member (curved surface mirror 170) different, it is possible to adjust the degree to which the display region (virtual image display surface) PS1 which is an inclined surface is separated from the road surface 40.

Further, as shown in FIG. 1C, the shape of the reflecting surface of the curved mirror (concave mirror or the like) 170, which is an optical member, is adjusted (or the shape of the display surface 164 of the display unit 160 is adjusted) for display. By changing the virtual image display distance near the end (near end) U1 on the side of the area PS1 near the vehicle 1, the vicinity of the near end U1 is bent toward the road surface and controlled to stand against the road surface ( In other words, elevation), thereby obtaining a display area PS1 having an inclined portion.

As shown on the upper side of FIG. 1 (C), the reflective surface 179 of the curved mirror 170 has three portions (Near (nearby display), Center (middle (center) display), and Far (far display)). It can be divided into parts).

Here, Near is a part that generates display light E1 (indicated by a long-dotted line in FIGS. 4A and 4B) corresponding to the near-end U1 of the display area PS1, and the Center is a display. Far is a portion that generates the display light E2 (indicated by a broken line) corresponding to the intermediate portion (central portion) U2 of the region PS1, and Far is the display light E3 (solid line) corresponding to the far end portion U3 of the display region PS1. Is the part that produces).

In FIG. 1 (C), the Center and Far portions are the same as the curved mirror (concave mirror or the like) 170 in the case of generating the flat display area PS1 shown in FIG. 1 (B). However, in FIG. 1 (C), the curvature of the Near portion is set to be smaller than that in FIG. 1 (B). Then, the magnification corresponding to the Near part becomes large.

The magnification (referred to as c) of the HUD device 100 is the distance (referred to as a) from the display surface 164 of the display unit 160 to the windshield 2 and the viewpoint of the light reflected by the windshield (reflecting translucent member 2). The distance to form an image at the image formation point via A can be expressed as c = b / a, but when the curvature of the Near part becomes smaller, a becomes smaller and the magnification becomes smaller. The image is formed at a position farther from the vehicle 1. That is, in the case of FIG. 1 (C), the virtual image display distance is larger than that of the case of FIG. 1 (B).

Therefore, the near-end U1 of the display region PS1 will be separated from the vehicle 1, and the near-end U1 will bow toward the road surface 40, and as a result, the first region Z1 will be formed. .. As a result, a display region PS1 having a first region Z1 and a second region Z2 can be obtained.

Next, refer to FIG. FIG. 2A is a diagram showing a main configuration of a HUD device mounted on a vehicle and a display example in a display area, and FIG. 2B is a diagram showing both a virtual image of a depth image and a virtual image of an upright image. It is a figure which shows the example of the display area | region which is composed of the 1st possible area and the 2nd area which displays a virtual image of a depth image. In FIG. 2, the same reference numerals are given to the portions common to those in FIG.

As shown in FIG. 2, the HUD device 100 includes a display unit (for example, a light transmission type screen) 160 having a display surface 164, a reflector 165, and a curved mirror (for example, a curved mirror) as an optical member for projecting display light. It is a concave mirror having a reflecting surface 179, and the reflecting surface may be a free curved surface) 170. The image displayed on the display unit 160 is projected onto the projected region 5 of the windshield 2 as a projected member via the reflecting mirror 165 and the curved mirror 170. The HUD device 100 may be provided with a plurality of curved mirrors. Further, in addition to the mirror (reflection optical element) of the present embodiment, or in place of a part (or all) of the mirror (reflection optical element) of the present embodiment, a refraction optical element such as a lens, a diffractive optical element, or the like can be used. A configuration including a functional optical element may be adopted.

Part of the display light of the image is reflected by the windshield 2 and is located inside (or on) the preset eyebox (three-dimensional but, for convenience, drawn in a plane) EB. Various images (virtual images) are displayed on the virtual display area (virtual image display surface) PS1 by being incident on the viewpoint (eye) A of the driver or the like and forming an image in front of the vehicle 1. In FIG. 2A, as display examples in the first area Z1 of the display area PS1, for example, a vehicle speed display SP which is an upright image (upright virtual image) and an image (virtual image) AW of a navigation arrow which is a depth display. 'It is shown. Further, in the second region Z2, an image (virtual image) AW of a navigation arrow extending from the front side to the back side of the vehicle 1 along the road surface 40 is shown.

As shown in FIG. 2B, the angle (inclination angle) formed by the first region Z1 with the road surface 40 is θ1 (0 <θ1 <90 °), and the angle formed by the second region Z2 with the road surface 40. (Inclination angle) is θ2 (0 <θ2 <θ1). Each of the first and second regions Z1 and Z2 is an inclined region (or a region having at least an inclined portion).

Next, refer to FIG. FIG. 3A is a diagram and a diagram showing a state in which an inclined surface (inclined display area) on which an arrow figure as a depth image is displayed is arranged in front and the viewer is viewing it with both eyes. 3 (B) is a diagram showing an image seen with the left eye, and FIG. 3 (C) is a diagram showing a depth image seen by fusing (combining) each image of the left eye and the right eye, FIG. 3 (C). D) is a diagram showing an image seen by the right eye.

In FIG. 3A, the midpoint C0 is drawn at the center position between the left eye A1 and the right eye A2. The image obtained by fusing the image seen by the left eye A1 and the image seen by the right eye A2 in the brain of the viewer can be said to be an image at the midpoint position C0 for convenience.

In FIG. 3A, an image (virtual image) AW of an inclined and extending navigation arrow is displayed in the second area Z2 of the display area PS1. When the images (images with binocular parallax) of the left and right eyes A1 and A2 shown in FIGS. 3 (B) and 3 (D) are fused (combined), a sense of depth (three-dimensional) as shown in FIG. 3 (C) is obtained. An image with a feeling) is visually recognized. In other words, the image (virtual image) AW of the arrow is naturally tilted to the back side and visually recognized due to the image shape change caused by the positional deviation between the upper end of the angle of view and the lower end of the angle of view in each of the left and right eyes A1 and A2. Will improve visibility or cognition

Next, refer to FIG. FIG. 4A is a diagram showing a state in which an inclined surface (inclined display area) on which a vehicle speed display as an upright image is displayed is arranged in front and the viewer is viewing it with both eyes. 4 (B) is a diagram showing an image seen with the left eye, and FIG. 4 (C) is a diagram showing an upright image seen by fusing (combining) each image of the left eye and the right eye, FIG. 4 (D) is a figure showing an image seen by the right eye.

In FIG. 4A, an image (virtual image) of a vehicle speed display SP (displayed as “120 km / h” as described in FIG. 4B and the like) is shown in the first region Z1 of the display region PS1. Has been done. This vehicle speed display SP is displayed as an upright image (upright virtual image) that is displayed in the inclined first region Z1 and is visually recognized in an upright position.

If the inclination angle of the first region Z1 with respect to the road surface 40 is not so small and it is erected to some extent, the cognition of the viewer is not impaired and the visual recognition as an upright image (reading the information as an upright image). ) Is possible. In this case, for example, when the images (images having binocular parallax) of the left and right eyes A1 and A2 shown in FIGS. 4 (B) and 4 (D) are fused (combined), the images shown in FIG. 4 (C) are obtained. The vehicle speed display SP is visually recognized as a standing image.

On the other hand, the appearance of the first region Z1 when the inclination angle with respect to the road surface 40 is small and the fusion (combination) of the images by the left and right eyes fails (when the fusion is not performed) varies from person to person. For example, it may appear tilted as a whole, or it may appear due to a change in the shape of either eye, but in any case, visibility decreases, recognition time increases, and it is subjective (psychological factor). ) Also cannot be seen favorably.

Next, refer to FIG. FIG. 5 (A) is a diagram showing a state in which a viewer is viewing a display area erected substantially perpendicular to the road surface with both eyes, and FIG. 5 (B) is a view of the display area in FIG. 5 (A). A diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 5C is a diagram showing the left eye. It is a figure which shows the image which fused (combined) each image of a right eye.

In the following description, it is assumed that the display area has a contour of a predetermined shape (here, a quadrangle), the ground (or the corresponding surface of the ground: road surface, etc.) side of the display area is the lower end (lower side), and the opposite side (lower side). The side away from the ground) is the upper end (upper side). The "quadrangle" indicating the shape of the display area shall be broadly interpreted to include, for example, a rectangle, a square, a trapezoid, a parallelogram, and the like.

In FIG. 5A, a display area (here, the first area Z1) standing substantially perpendicular to the road surface 40 is shown in front of the viewer. The viewer is looking at the image (virtual image) displayed in the first region Z1 with both eyes A1 and A2. As shown in FIG. 5C, the displayed image (virtual image) is the vehicle speed display SP shown above.

In FIG. 5A, the lower end of the angle of view (hereinafter, may be simply referred to as the lower end or the lower side) in the display area (first area Z1) is indicated by a PL reference numeral, and the upper end of the angle of view (hereinafter, may be simply referred to as the lower end or the lower side) is shown. (Sometimes referred to simply as the top or top) is indicated with a PU sign.

5 (B) shows the convergence angle due to the binocular parallax of the viewer in a plan view when looking from the upper side to the lower side (in the figure, the −Y direction side indicated by the arrow) in FIG. 5 (A). Is shown.

Further, in FIG. 5B, a pair of points (which can be provided at arbitrary positions) corresponding to each other at each of the lower end (lower side) PL and the upper end (upper side) PU are preferably provided, but preferably, for example, each end (each side). ) Is set to the right end point or the left end point). In FIG. 5B, the right end point R1 at the lower end (lower side) and the right end point R2 at the upper end (upper side) are set. The point R1 is referred to as a first point, and the point R2 is referred to as a second point.

The convergence angle (the angle formed by the visual axis indicating the line-of-sight direction of each eye A1 and A2) when the first point R1 is viewed from the left and right eyes A1 and A2 is defined as the first convergence angle θL, and the second point. The congestion angle when looking at R2 is defined as the second congestion angle θU, and the difference between the first congestion angle θL and the second congestion angle θU (the second congestion angle θU is subtracted from the first congestion angle θL). Difference) is defined as "convergence angle difference". In other words, this convergence angle difference can be said to be "convergence angle difference between the upper end (or upper side) and the lower end (or lower side) of the display area".

In the example of FIG. 5, since the display area (first area Z1) is erected at a substantially right angle to the road surface 40, the contour quadrangle of the display area (first area Z1) is viewed from above. Visually, the upper end (upper side) PU and the lower end (lower side) PL of the quadrangle overlap, and the first point R1 and the second point R2 overlap. Here, if the length of the vertical side of the quadrangle (the length of the line segment indicating the first region Z1 in FIG. 5A: in other words, the height with respect to the road surface 40 of the first region) is small. Then, the difference in the distance between the first and second points R1 and R2 and the left and right eyes A1 and A2 due to the difference in the height positions of the first and second points R1 and R2 (of the distance). Fluctuations) can be ignored. In the above case, the values of the first and second convergence angles θL and θU for the first and second points R1 and R2 are the same (substantially the same), and the convergence angle difference is zero (substantially zero). ..

As shown in FIG. 5C, an image obtained by fusing (combining) each image of the left eye and the right eye (an image at the center position C0, abbreviated as an image of C0) is visually recognized as a standing image. There is no problem with the visibility of the vehicle speed display SP.

Next, refer to FIG. FIG. 6A is a diagram showing a state in which a viewer is viewing a display area inclined by approximately 45 ° with respect to the road surface with both eyes, and FIG. 6B is a display area in FIG. 6A. A diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 6C is a diagram showing the left eye. FIG. 6 (D) is a diagram showing an upright image obtained by fusing (synthesizing) each image of the left eye and the right eye, and FIG. 6 (E) is a diagram showing an image viewed with the right eye. It is a figure which shows.

As shown in FIG. 6A, the display area (first area Z1) is arranged at an inclination of approximately 45 ° with respect to the road surface 40. The lower end (lower side) of the quadrangle showing the outline of the first region Z1 moves to the side of the viewer. In FIG. 6B, the lower end (lower side) PL is closer to the viewer than the upper end (upper side) PU. As a result, there is a difference between the values of the first convergence angle θL with respect to the first point R1 and the second convergence angle θU with respect to the second point R2. In other words, the first convergence angle θL is larger than the second convergence angle θU. Therefore, the convergence angle difference is α (α is an integer larger than 0).

Refer to FIGS. 6 (C) and 6 (E). Since the display area Z1 is inclined toward the back side toward the upper side, the burden on the left eye A1 and the right eye A2 becomes large at this point. Further, due to the binocular disparity, the quadrangle is distorted to the left in the image seen by the left eye A1, and the quadrangle is distorted to the right in the image seen by the right eye A2, and as a result, it is visually recognized as a substantially parallelogram shape. At this point as well, it becomes difficult to visually recognize the upright image (vehicle speed display SP).

However, the human eye can recognize an upright image by correcting a certain depth, left-right distortion, etc., and in the example of FIG. 6, the limit of the correction function (recognition function) is not exceeded. Therefore, as shown in FIG. 6D, the vehicle speed display SP as an upright image can be visually recognized correctly for the time being.

Next, refer to FIG. 7. FIG. 7A is a diagram showing a state in which a viewer is viewing a display area inclined by approximately 30 ° with respect to the road surface with both eyes, and FIG. 7B is a display area in FIG. 7A. FIG. 7 (C) is a diagram showing the convergence angles of both eyes with respect to the first right end point of the upper end (upper side) and the second right end point of the lower end (lower side) corresponding to the first right end point, FIG. 7 (C) is the left eye. FIG. 7 (D) is a diagram showing the images seen in the above, and FIG. 7 (D) is a diagram showing visual perception that is difficult to see due to double vision when each image of the left eye and the right eye is fused (combined). , Is a diagram showing an image seen with the right eye.

As shown in FIG. 7A, the display area (first area Z1) is further inclined with respect to the road surface 40. As shown in FIG. 7B, the lower end (lower side) PL of the quadrangle further moves toward the viewer and approaches the viewer. As a result, the first convergence angle θL is further increased. Therefore, the difference from the second convergence angle θU becomes large, and the convergence angle difference (θL−θU) becomes β (β is an integer satisfying α <β).

In the example of FIG. 7, the limit of the correction function of the human depth and the left-right distortion is exceeded, and the image cannot be fused correctly. Therefore, as shown in FIGS. 7 (C) to 7 (E), the vehicle speed display SP, which is an upright image, cannot be visually recognized correctly. Since it is difficult to specifically describe the figure, it is simply described as SP in the figure.

As described above with reference to FIGS. 5 to 7, the "convergence angle difference (θL-θU) between the upper end (upper side) and the lower end (lower side) of the display area" is the inclination of the display area with respect to the ground (corresponding surface thereof). Can be an indicator of the degree of.

Further, since the convergence angles θL and θU vary depending on the distance from the eyes A1 and A2 of the viewer, distance information is included, and therefore the convergence angle difference (θL−θU) includes the distance. It is one integrated index (threshold value) having information on the degree of inclination of the display area (or the virtual image display surface, etc.) with respect to the ground (corresponding surface thereof). It is not necessary to set the inclination with the precondition of the distance, such as the number of inclination angles at the distance of several meters as in the conventional case. Therefore, by introducing this index into the design of the HUD device or the like, the setting of the inclination of the display area or the like can be made more efficient (easy).

Here, the visibility of the upright image varies from person to person and cannot be unequivocally stated, but the visibility of the image to be displayed (first factor), the time required for viewing (second factor), and discomfort or discomfort. It is possible to objectively determine whether or not a normal upright image can be visually recognized based on at least one of psychological factors (third factor) such as pleasure. Then, by using the above index in the determination, a threshold value that can be used in the determination can be obtained.

(Experimental result)
The present inventor, with the cooperation of a plurality of persons, tried whether or not an upright image can be correctly determined using the above-mentioned convergence angle difference as an index based on each of the above-mentioned first to third factors. Here, when NG is detected by all three factors, it is difficult to visually recognize the upright image, and when there is one or two NGs, the upright image is visible.

As a result, it was found that it became difficult to visually recognize when the difference in the convergence angle between the upper end and the lower end of the image to be visually recognized upright was 0.182 °. When the threshold is on the order of 0.1, 0.182 is rounded to 0.2. Therefore, 0.2 ° could be extracted as an example of a preferable threshold value. Therefore, by setting the convergence angle difference to less than 0.2 °, the upright image can be visually recognized.

Specifically, this "predetermined threshold value" can be used as, for example, a "normal visual visibility determination threshold value", and an example of a preferable value thereof is the above-mentioned 0.2 °.

By utilizing this threshold value (index), for example, a design that enables an image of content (upright image) to be visually recognized upright while suppressing a decrease in visibility is made more efficient or easier. Will be done. In addition, this new index (convergence angle difference, or tilt distortion angle caused by this (see the angle θd in FIG. 6C)) is used for calibration of the HUD device, initialization of the HUD device, and functions of the HUD device. It can also be used for simulations and the like, and effects such as improving the efficiency of each process can be obtained.

Further, as shown in FIG. 2A, the display area includes a first area Z1 capable of displaying both a depth image and an upright image, and a second area Z2 suitable for displaying a depth image. The difference in convergence angle between the upper end and the lower end of the display region in the second region Z2 is preferably set to the above-mentioned predetermined threshold value (preferably 0.2 °) or more.

As described above, the threshold value is set based on the visibility of the upright image and the like, and above the threshold value, the visibility of the upright image is lowered and it is not suitable for displaying the upright image. In other words, it is suitable for displaying a depth image expressed in an inclined manner (including an image that floats in the air and extends substantially parallel to the road surface, etc., or gives a visual sense superimposed on the road surface). It can be said that. Therefore, for the image (virtual image) displayed in the second region Z2, the convergence angle difference is set to be equal to or larger than the threshold value. Thereby, for example, when an upright image is displayed in the first region Z1 and a depth image is displayed in the second region Z2, appropriate visibility of each image can be ensured.

Further, when the image angle in the vertical direction (or height direction) seen from the viewer is referred to as a vertical angle of view, the limitation of the convergence angle difference by a predetermined threshold is the content of an upright image having a vertical angle of view of 0.75 ° or less. May be applied to.

In other words, as the size of the displayed content increases, it becomes more difficult to fuse the image of the left eye and the image of the right eye in the brain even with the same convergence angle difference, and the vertical angle of view is 0. The above threshold value is applied to small content of 75 ° or less, and the convergence angle difference between the upper end and the lower end is set to be less than the threshold value.

In addition, it has been confirmed that upright content larger than this size is more annoying from the viewpoint of visibility obstruction in the HUD device 100, and it cannot be said that the current feasibility is high. Therefore, it is considered that there is no particular problem even if the above threshold value is applied only to the display contents having a predetermined size or less.

Next, refer to FIG. 8 (A) and 8 (B) are flowcharts showing an example of a design method of a HUD device (oblique image plane HUD device). In FIG. 8A, in the oblique image plane HUD device, the convergence angle difference between the upper end and the lower end of the display area of the information image (upright image) to be visually recognized upright (or the tilt distortion angle caused by the difference) is shown. Each part is designed so as to be less than a predetermined threshold value (preferably less than 0.2 °) determined based on at least one of psychological factors such as image visibility, time required for visual recognition, and discomfort and discomfort (preferably less than 0.2 °). Step S1).

In FIG. 8B, the display area is tilted and the first area in which both the information image (depth image) to be visually recognized by tilting and the information image (upright image) to be visually recognized in an upright position are displayed and the display area is tilted. The information image (depth image) to be visually recognized is divided into a second area to be displayed (step S2). Subsequently, preferably, for the content having a vertical angle of view of 0.75 ° or less, the convergence angle difference between the upper end and the lower end in the first region is designed to be less than a predetermined threshold value (preferably less than 0.2 °). The convergence angle difference between the upper end and the lower end of the second region is designed to be equal to or larger than a predetermined threshold value (step S3).

Next, refer to FIG. FIG. 9 is a diagram showing a configuration example of a display control unit (control unit) in the HUD device. The upper view of FIG. 9 is almost the same as that of FIG. 1 (A). However, in FIG. 9, a line-of-sight detection camera 188 and a viewpoint position detection unit 192 are provided.

The display control unit (control unit) 190 has an input / output (I / O) interface 193 and an image processing unit 194. The image processing unit 194 includes an image generation control unit 195, a ROM (having an upright image table 199 and a depth image table 200) 198, and a VRAM (having a warping parameter 196 and a post-warping data storage buffer 197) 201. And an image generation unit (image rendering unit) 202.

For example, in the example shown in FIG. 2A, the image generation control unit 195 arranges the vehicle speed display SP and the arrow display AW'in the first region Z1 and the arrow display AW in the second region. It is possible to control the display position of the content, such as arranging it in Z2. Further, the display control unit (control unit) 190 performs control such as setting the display area at an appropriate position by using the above threshold value at the time of calibration or initialization of the HUD device 100, for example. You can also do it.

Next, refer to FIG. 10 (A) and 10 (B) are views showing another example of the inclined display area. The device configuration itself is the same as in FIG. 1 (A).

The cross-sectional shape of the vehicle 1 in the display area PS1 as seen from the width direction (horizontal direction, X direction) is not limited to the one in which the driver side is convex as shown in FIG. As shown in FIG. 10A, the display area PS1 may have a concave shape on the driver side. Further, the display area PS1 does not have to be curved as shown in FIG. 10 (B). These are examples, and display areas having various cross-sectional shapes can be assumed.

It was confirmed in the experiment that the configuration of this embodiment has the effect of improving the visibility of the image. In this experimental example, a sensory evaluation was performed in which a subject was asked to visually recognize a virtual image displayed by multiple types of head-up display devices and to answer whether or not he / she felt uncomfortable. In this experiment, a plurality of types of head-up display devices display upright images having different convergence gaps at the upper and lower ends. Here, in any of the plurality of types of head-up display devices, the upright image has a shape that is visually recognized as a rectangle in the vertical and horizontal directions when viewed from the observation position of the subject, and the vertical angle of view is set to 0.75 °. Will be done.

FIG. 11 is a graph of experimental results showing the proportion (vertical axis) of those who answered that they did not feel uncomfortable with each convergence angle difference (horizontal axis). It can be seen that the proportion of people who answered that they did not feel uncomfortable increased as the difference in the convergence angle between the upper end and the lower end became smaller when visually recognizing the upright image.

When the convergence angle difference was 0.22 [degree], the percentage of those who answered that they did not feel uncomfortable was 0 [%], and it was found that all the subjects answered that they were uncomfortable. Further, when the convergence angle difference is 0.20 degree], the percentage of those who answered that they do not feel discomfort is 20 [%], and when the convergence angle difference is 0.17 [degree], discomfort is caused. When the percentage of people who answered that they do not remember is 40 [%] and the convergence angle difference is 0.15 [degree], when it is 40 [%] and the convergence angle difference is 0.14 [degree]. , 60 [%], 80 [%] when the convergence angle difference is 0.12 [degree], and 100 [%] when the convergence angle difference is 0.09 [degree]. Then, when the convergence angle difference was 0.06 [degree], it was 100 [%].

In the above experimental results, all respondents felt uncomfortable when the congestion gap was 0.22 [image] or more, and answered that they felt uncomfortable when the congestion gap was 0.20 [image] or less. When the number of people decreases and the upright image is visually recognized, it is considered preferable that the convergence angle difference between the upper end and the lower end of the upright image is 0.20 [degree] or less.

In addition, it was confirmed that setting the convergence angle difference to 0.14 [degree] or less had the effect that more than half of the people did not feel uncomfortable. That is, it can be said that setting the convergence angle difference to 0.14 [degree] or less is more preferable because it is possible to sufficiently obtain an effect of not causing discomfort in visually recognizing an upright image.

In addition, it was confirmed that setting the convergence angle difference to 0.09 [degree] or less had the effect that everyone did not feel uncomfortable. That is, it can be said that setting the convergence angle difference to 0.09 [degree] or less is more preferable because it is possible to sufficiently obtain an effect of not causing discomfort in visually recognizing an upright image.

The present invention can be widely applied to a parallax type HUD device for incident an image having parallax, a light ray reproduction type HUD device using a lenticular lens or the like, and the like.

In this specification, the term vehicle can be broadly interpreted as a vehicle. In addition, terms related to navigation (for example, navigation arrows, etc.) shall be interpreted in a broad sense, taking into consideration, for example, the viewpoint of navigation information in a broad sense useful for vehicle operation, and road signs and the like can also be included. .. Further, the upright image can also be said to be a face-to-face image that the viewer sees face-to-face, and can be widely interpreted without being bound by the name. Further, the HUD device shall include a device used as a simulator (for example, a simulator as an aircraft simulator, a simulator as a game device, etc.).

The present invention is not limited to the above-mentioned exemplary embodiments, and those skilled in the art will be able to easily modify the above-mentioned exemplary embodiments to the extent included in the claims. ..

1 ... Vehicle (own vehicle), 2 ... Projected member (reflected translucent member, windshield, etc.), 5 ... Projection area, 40 ... Road surface, 100 ... HUD device, 120 ... An optical system including an optical member, 150 ... a light projecting unit (image projection unit), 160 ... a display unit (for example, a liquid crystal display device, a screen, etc.), 164 ... a display surface, 170 ... a curved mirror. (Concave mirror, etc.) 179 ... Reflective surface, 188 ... Line-of-sight detection camera, 190 ... Display control unit (control unit), 192 ... Viewpoint position detection unit, 194 ... Image processing unit, 195 ... Image generation control unit, 196 ... Warping parameter, 197 ... Data buffer after warping processing, 198 ... ROM, 199 ... Upright image table, 200 ... Depth image table, 201. VRAM (storage device for image processing), 202 ... image generation unit (image rendering unit), EB ... eye box, PS1 ... display area (imaginary image display surface), Z1 ... upright image And a first display area capable of displaying both a depth image, Z2 ... A second display area for displaying a depth image.

Claims

An image display unit that displays an image and
By projecting the light of the image displayed by the image display unit toward the projected member, the viewer can visually recognize the virtual image of the image within a virtual display area in the real space in front of the viewer. Optical system and
A control unit that controls the display of the image in the image display unit,
Have,
The direction toward the front of the viewer in the real space is defined as the forward direction.
The direction perpendicular to the front direction and along the line segment connecting the left and right eyes of the viewer is defined as the left-right direction.
When the direction along the line segment orthogonal to the front direction and the left-right direction is the vertical direction or the height direction, the direction away from the ground or the surface corresponding to the ground in the real space is the upward direction, and the approaching direction is the downward direction. ,
The control unit
In the display area, which is an inclined surface of a flat surface or a curved surface that inclines from the side close to the viewer and the lower side to the far side and the upper side with respect to the ground or a surface corresponding to the ground in the real space. In addition, control is performed to display an upright image, which is an upright image to be visually recognized.
The upright image is displayed in a display area that is the outline of a quadrangle when viewed from the viewer.
The difference in convergence angle between the upper end and the lower end of the display area is set to be less than a predetermined threshold value determined based on at least one of the visibility of the image, the time required for visual recognition, and psychological factors such as discomfort and discomfort. ,
A head-up display device that features this.
The display area includes a first area in which both a virtual image of a depth image, which is an image to be visually recognized by being tilted, and a virtual image of the upright image can be displayed, and a second area for displaying a virtual image of the depth image. Divided into
The convergence angle difference between the upper end and the lower end of the display area in the first region is set to be less than the predetermined threshold value.
The convergence angle difference between the upper end and the lower end of the display area in the second region is set to be equal to or higher than the predetermined threshold value.
The head-up display device according to claim 1, wherein the head-up display device is characterized in that.
The predetermined threshold value functions as a normal visibility determination threshold for determining the normal visibility of the upright image.
The convergence angle difference as the predetermined threshold value is set to 0.2 °.
The head-up display device according to claim 1 or 2, wherein the head-up display device is characterized in that.
When the angle of view in the vertical direction (or height direction) seen from the viewer is referred to as a vertical angle of view.
The limitation of the convergence angle difference by the predetermined threshold value is applied to the content of an upright image having a vertical angle of view of 0.75 ° or less.
The head-up display device according to any one of claims 1 to 3, wherein the head-up display device is characterized in that.