JPH0571415B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an in-vehicle head-up display device, and more particularly to an in-vehicle head-up display device that uses the windshield of an automobile to display various information using a virtual image optical system. The present invention relates to a head-up display device for use in a vehicle.

[Conventional technology]

2. Description of the Related Art Devices have been proposed that display information such as the speed, time, and engine speed of a vehicle by forming a virtual image in front of the windshield using internal reflections of the windshield. Such a device is called an in-vehicle head up display device (hereinafter referred to as HUD).

Figures 5 and 6 have been proposed previously.
Shows the basic structure of the HUD. As shown in FIG. 5, the apparatus is comprised of a display device 11 incorporated in the center of a dart board, a (refractive) optical system 12 such as a lens, and a reflective optical system using a windshield 13. The display device uses LED, LCD, etc., and the small image on the display is produced by optical system 1.
2. The image is magnified by a virtual image optical system consisting of the windshield 13 and formed as a virtual image in front of the windshield 13.

Therefore, as shown in Figure 6, the driver should:
The virtual image displayed on the display device 11 of the HUD (displaying speed in this case) is perceived as if it were present at a predetermined distance in front of the vehicle 14.

[Problems to be Solved by the Invention] Technology for forming image information such as display information by LEDs, LCDs, etc., and image information such as field frames within a predetermined optical field of view has been used for a long time in camera viewfinders. HUD technology is basically the same as this display technology, but in the case of HUDs, there is a problem that needs to be solved in that a windshield is used for the reflective optical system.

This is a problem of binocular parallax caused by the direction of reflection from the windshield.

That is, as shown in FIG. 7, when a HUD unit 1 consisting of a display device and an optical system is placed at the center of the dash board and a virtual image is reflected toward the driver seated on the right seat of the automobile, As shown in FIG. 8, the reflection points 19, 19 on the windshield of the same virtual image reaching the driver's right eye 16R and left eye 16L end up at different positions due to the parallax between the left and right eyes.

FIG. 9 shows the positions of the driver's eyes 16R, 16L, the HUD unit (indicated as object point 1'), and the reflection point on the windshield from above.

Here, for ease of explanation, the windshield is assumed to be a flat glass, and problems in the following condition settings will be described.

For example, in Fig. 9, the average distance L1 between the left and right eyes is approximately 70 mm, and from the center position of eyes 16L and 16R to the midpoint 1 of the reflection point of the left and right eyes on the windshield.
The distance S1' along the longitudinal direction of the car up to 9' is approximately
The length shall be 850mm. In addition, as shown in Figure 10, the HUD
The virtual image is incident on the unit 1 from below the eye, and the height difference H between the center point 19' of the reflection point and the eye is approximately 30 mm. Furthermore, the distance L2 from the line passing through the midpoint 19' of the reflection point along the longitudinal direction of the vehicle to the center of the surface is approximately 210 mm. Also, the midpoint 1 of the reflection point
9', the windshield shall have an inclination of 28 degrees with respect to the horizontal plane.

In other words, the HUD unit allows light to enter the windshield from the lower left front (in the case of a right-hand drive vehicle), and the reflected light travels from the reflection point to the upper right eye.

Under these conditions, as shown in Figure 11, the y-axis along the vertical direction and the z-axis along the left-right direction of the car
Reflection point 1 of the left eye relative to the plane formed by the axis
9L is a position shifted to the lower left of the reflection point 19R of the right eye. Under the above conditions, 1 reflection point on the yz plane
When projecting 9L and 19R, the difference in height is 7.5mm.
The difference between left and right is 66.5mm.

In Figure 9, the distance S1' (850 mm) from the center of the eye to the reflection point measured in the longitudinal direction of the car, the height difference H (30 mm) between the eye and the center 19' of the reflection point, and the center of the eye and the reflection point. Distance L2 (210mm) of the line passing through the center of
From the conditions, the straight line distance S1 from the center point of the eye to the reflection point
is 876 mm, and at this time, the vertical binocular parallax θ (=
tan ^-1 (75/876)) is 0.49°.

Therefore, depending on the size of the image in the horizontal direction, the image reflected by the windshield becomes a double image due to the binocular parallax described above. Basically, the human eye is not good at adjusting the left and right eyes in the vertical direction, and if the same image is reflected on the left and right eyes for a long time with the above parallax, it can cause eye strain. This is a big problem from the standpoint of preventing danger. Regarding the above-mentioned binocular parallax, we did not consider the vertical and horizontal curvature of the windshield, but if the curvature is taken into consideration, the deviation of the virtual image becomes larger.

As described above, when using a windshield as a reflecting means, there is a problem of parallax, and unless this problem is solved, it will not be possible for the driver to see a clear displayed image without causing eye strain.

Therefore, in view of the above-mentioned points, the present invention solves the problem of binocular parallax caused by reflection on the windshield, and allows the driver to visually recognize a clear displayed image without causing eye strain. The object of the present invention is to provide an in-vehicle head-up display device that can perform the following functions.

[Means for solving problems]

In order to achieve the above object, an in-vehicle head-up display device according to the present invention includes a windshield of an automobile used as a reflective optical system, a display means for displaying various information, and a virtual image of a display image of the display means. An in-vehicle head-up display device is provided with an optical system that causes the image to be incident on the windshield and reflected toward the driver, and allows the driver to visually recognize a virtual image of the display image formed in front of the windshield. Provided between the optical system and the windshield, it corrects binocular parallax by changing the direction in which light from each point on the display image goes to the driver's left and right eyes through reflection on the windshield. It is characterized by having a prism shaped like this.

The present invention is also characterized in that the prism corrects binocular disparity in the height direction.

[Effect]

According to the above configuration, the display image of the display means projected onto the windshield through the optical system passes through the prism. When passing through this prism, the shape of the prism changes the direction in which the light from each point on the display image goes toward the driver's left and right eyes, respectively, so as to correct binocular parallax.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Regarding windshields, we will explain the technology to prevent binocular parallax.

In the conventional example section, with the condition settings shown in relation to FIGS. 8 and 9, the shift in the reflection point of the HUD light image incident on the left and right eyes on the windshield is:
Approximately 66.5mm in the horizontal direction and 7.5mm in the vertical direction,
It was mentioned that the vertical parallax θ at that time is 0.49°.

As can be seen from the fact that stereoscopic vision is obtained by the horizontal parallax between the left and right eyes, the difference in the left-right direction among the above differences does not pose much of a problem even without correction. Therefore, if only the vertical parallax between the left and right eyes is corrected, a satisfactory display image can be obtained even when reflection is performed obliquely.

Therefore, in FIGS. 8 and 9, if the reflection point of the left eye is moved 7.5 mm lower than that of the right eye and upward, the vertical parallax will be eliminated and the displayed image should become considerably easier to see.

Therefore, in this embodiment, as shown in FIG. 1, the optical system 1 of the HUD unit is
Correction is performed to move the light flux that exits from the front window and goes to the left eye through the windshield. In FIG. 1, in order to reduce the size of the HUD unit in the height direction of the dash board, the image on the display 11 is reflected once by a mirror 1a before entering the optical system 12.

FIG. 2 shows the action of the prism 30 in detail. In the figure, the symbol K _L is a light beam heading toward the left eye before correction, and the light beam K _R heading toward the right eye is reflected at a reflection point B lower than the reflection point A. , toward the left eye.
The angle θ between the two light beams after reflection is the vertical parallax.

As shown in FIG. 3, the prism 30 has a cross-sectional shape in which only the upper surface is inclined, and is thicker on the front side of the vehicle body. In addition, the apex angle of the prism is varied so that it is large on the left side, where the light beam heading toward the left eye passes, and becomes small on the right side, where the light flux heading toward the right eye passes, and the upper surface of the prism has a curved shape.
When a virtual image of a display image is projected through such a prism with the settings shown in connection with FIGS. 8 and 9, the light beam heading toward the left eye is moved as indicated by the symbol K _L '.

In other words, the prism cross section shown in Figure 2 is the cross section through which the light flux K _L heading toward the left eye passes, and the light flux K _R towards the right eye passes through the prism cross section.
passes through a cross section corresponding to the back of the figure (to the right of the vehicle body) from this cross section. In the cross section through which the light beam K _R passes, the apex angle of the prism 30 is smaller, and the light beam K _R passes through substantially the same position as in the case without prism correction. On the other hand, the light beam K _L ' passes through a cross section with a larger apex angle, is refracted by the angle θ to be corrected, is reflected at a point B' having the same height as the reflection point A of the right eye, and heads toward the left eye.

As described above, due to the action of the prism, both light beams K _L ′ and K _R heading from the windshield 13 to the eyes pass through the horizontal plane that includes the left and right eyes, eliminating the vertical parallax and reducing the vertical binocular parallax. You can get a display image that is not easy to see. However, in the above action, the luminous flux K _L ′ before being reflected by the windshield,
Since the inclination angles of K _R are different, the directions of the perpendiculars B _v and A _v at the reflection points B' and A are naturally different.

Here, an example of a prism shape for eliminating the binocular parallax of 0.49° will be specifically explained using FIG. 3. First, the effective diameter of the optical system lens is φ120mm, and the horizontal distance between reflection points A and B is 66.5mm.
If the width b of the prism 30 is 1.80 times, the width b of the prism 30 is 130 mm.
The depth a is approximately 53 mm based on the aspect ratio of the displayed image. Furthermore, the prism 30 has a bottom surface perpendicular to the optical axis of the optical system 12, and its thickness t is 1.0 mm. The refractive index n of the glass used for the prism is 1.492.

In Figure 3, the required refraction angle with respect to the maximum apex angle θ ₀ on the x-axis and the refractive index n is θ=sin ^-1 (n sinθ ₀ )−θ ₀ (=
0.49°) ...(1), and the angular change θ _T in the long side direction of the prism 30 is set as θ _T =1.80θ ₀ and by transforming equation (1), tanθ ₀ = sin0.49°/n− cos0.49° = sin0.49°/1.492−cos0.49° Therefore, θ ₀ =1.0° and θ _T =1.8° are obtained.

The height (thickness) z of the prism 30 is expressed as z=(a-x)・tan{b-y/b・θ ₀ }+t...(2), so substitute the above dimensions and angles into this. z=(53-x)・tan {1-y/130)×1°} +1.0...(3) Figure 4 shows the height z of the prism in the xy plane based on equation (3). is shown as contour lines, and as can be seen from the figure, the prism 30 is formed into a curved upper surface so that it is thicker at the front left side and thinner at the front right side.

As described above, it is possible to eliminate the vertical binocular parallax that occurs when the driver's eyes are diagonally reflected from the HUD to the windshield, giving the driver a sense of dignity without causing eye strain. A high display image can be visually recognized. Although the curved shape of the windshield was not considered in Figures 3 and 4, if the windshield is curved, especially if it has a large curved surface in the left and right direction, it is possible to reflect the curvature of the prism shape. Display images without parallax can be obtained.

In the above embodiment, the mirror 1a is provided between the display 11 and the optical system 12, but this may be omitted so that the display 11 can be placed on the optical axis of the optical system 12. .

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the display image of the display means projected onto the windshield through the optical system passes through the prism provided between the optical system and the windshield, and at this time, the display image is projected onto the windshield through the optical system. The direction in which the light from each point on the image goes to the driver's left and right eyes is changed, correcting binocular parallax, which eliminates the problem of binocular parallax caused by reflections on the windshield. The driver can see a clear, high-quality display image without causing eye strain, and can provide high driving performance and safety to the vehicle in which it is installed.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the HUD according to the present invention, and FIG. 1 is an explanatory diagram showing an outline of the device configuration of the HUD that solves the problem of binocular parallax.
Figure 2 is an explanatory diagram showing the action of the prism in Figure 1, Figure 3 is a perspective view of the prism in Figure 1, Figure 4 is a diagram explaining the shape of the prism in Figure 1, and Figure 5 is a diagram explaining the shape of the prism in Figure 1.
The figures below show the conventional structure, and Figure 5 shows the conventional structure.
FIG. 6 is an explanatory diagram showing the basic structure of the HUD, FIG. 6 is an explanatory diagram showing the projection of a display image, and FIGS. 7 to 11 are explanatory diagrams showing binocular parallax in the HUD. 1...HUD unit, 11...Display device, 1
2...Optical system, 13...Windshield, 16...
...eyes, 30...prism.

Claims (1)

[Scope of Claims] 1. A windshield of an automobile used as a reflective optical system, a display means for displaying various information, and a virtual image of a display image of the display means incident on the windshield and reflected toward the driver. An in-vehicle head-up display device comprising an optical system and configured to allow a driver to visually recognize a virtual image of the display image formed in front of the windshield;
The vehicle is characterized by comprising a prism shaped to correct binocular parallax by changing the directions of light from each point on the displayed image toward the left and right eyes of the driver by reflection on the windshield. An in-vehicle head-up display device. 2. The in-vehicle head-up display device according to claim 1, wherein the prism corrects binocular parallax in the height direction.