JP2000347127A - Head-up display device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish a high enlargement ratio by suppressing the distortion of a virtual image (displayed image as target) and to improve display quality and visibility while using a small-sized display device. SOLUTION: Image display light is emitted from a display device 5, and the virtual image O' is observed ahead of a window shield WS at a position of a viewing point 1 through an optical system consisting of the combination of mirrors 3 and 4 and a combiner 2. In the optical system having an actual arrangement relation matched with vertical and horizontal directions, the principal point position in the vertical direction is different from that in the horizontal direction, and then, the optical system can be replaced with an equivalent single lens whose focal distance in the vertical direction is different from that in the horizontal direction. By making the horizontal enlargement ratio of the equivalent single lens lower than the vertical enlargement ratio, the horizontal focal distance becomes longer, then, the F value in the horizontal direction is increased. Thus, the horizontal outside dimension of each mirror 3 and 4 is reduced, and also, the high enlargement ratio is accomplished by suppressing the horizontal distortion while using the small-sized display device, and the display quality and the visibility are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head-up display device for a vehicle in which various kinds of information on a display device can be visually recognized within the field of view of the windshield by utilizing the reflection of the inner surface of the windshield of the vehicle.

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a head-up display device for a vehicle, there is Japanese Patent Application Laid-Open No. 11-6.
One disclosed in Japanese Patent No. 4779 is known. In this device, distortion of a target display image (virtual image as an observation target) based on a difference between a curvature in a horizontal direction and a curvature in a vertical direction of a windshield (a windshield) is reduced. A technique for improving simultaneous visibility with a scene in front is disclosed.

[0003]

However, since the field of view of a head-up display device for a vehicle is generally larger in the horizontal (left-right) direction than in the vertical direction, it is composed of a display and a part of the inner surface of a windshield. The external dimensions of the mirror as an optical system between the mirror and the combiner become large. If it is attempted to enlarge the image at the same magnification vertically and horizontally, the F value in the horizontal direction (focal length / outside dimension in the horizontal direction) becomes smaller than the F value in the vertical direction (focal length / outside dimension in the vertical direction). Then, the distortion in the horizontal direction in the target display image becomes larger than the distortion in the vertical direction, and this distortion becomes more remarkable as the enlargement ratio increases. Therefore, if a display device having a large display image is used to reduce the enlargement ratio, the cost is increased, and it is difficult to accommodate the device itself.
For this reason, if the horizontal magnification is made smaller than the vertical magnification in order to suppress distortion due to the high magnification, the target display image position will be different between the vertical and horizontal directions, and the display quality will deteriorate due to blurring. However, there is a problem that the visibility is lowered.

Therefore, the present invention has been made to solve such a problem, and achieves a high magnifying power by suppressing a distortion in a horizontal direction in a target display image by using a small-sized display, thereby achieving a high display quality. Another object of the present invention is to provide a vehicle head-up display device having excellent visibility.

[0005]

According to the head-up display device for a vehicle according to the present invention, the display device has a larger dimensional ratio in the horizontal direction than in the vertical / horizontal dimensional ratio of the target display image on the display surface. Image display light projected from the display surface is observed at a viewpoint position in front of the windshield via an optical system including at least one lens and a combiner. Here, in an optical system based on a combination of a lens and a combiner whose actual arrangement relationship is the same in the vertical and horizontal directions, the principal point position is different between the vertical and horizontal directions, and the horizontal magnification is the vertical magnification. By making the focal length smaller, the focal length in the horizontal direction increases, and the F value in the horizontal direction can be increased.
As a result, the external dimensions of the lens in the horizontal direction can be reduced, so that a high-magnification factor can be achieved while suppressing distortion in the horizontal direction using a small-sized display, and the display quality and visibility are improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic configuration diagram showing a windshield and an instrument panel around which a head-up display device for a vehicle according to an embodiment of the present invention is applied.

In FIG. 1, a head-up display device 100 for a vehicle includes a combiner 2 configured by using a part of the inner surface of a windshield WS to function as a half mirror, mirrors (concave mirrors) 3 and 4, and image display light. And a display 5 for projecting. Here, the mirrors 3 and 4 are optically arranged between the combiner 2 and the display 5, and the mirrors 3 and 4 and the display 5 are connected to the instrument panel IP.
It is built in. Also, instrument panel IP
Is provided with a transparent cover (not shown) through which image display light from the display 5 can pass.

The display 5 is composed of, for example, a liquid crystal display panel with a backlight, a fluorescent display tube or the like, and the image display light projected from the display 5 receives mirrors 4 and 3 forming an optical system. Reflected by the combiner 2 and a virtual image (target display image) O ′ in front of the windshield WS as the viewpoint 1
The position is recognized by the driver. Here, according to the combiner 2 configured using a part of the inner surface of the windshield WS, the curvature of the reflecting surface in the vertical direction is set to be larger than the curvature in the horizontal direction.

As described above, also in the head-up display device 100 for a vehicle, since the field of view is larger in the horizontal (left-right) direction than in the vertical direction, the mirrors 3 and 4 also have outer dimensions corresponding to the horizontal direction. When it is attempted to greatly enlarge the image at the same vertical and horizontal magnifications, the F value in the horizontal direction (focal length / outside dimension in the horizontal direction) becomes smaller than the F value in the vertical direction (focal length / outside dimension in the vertical direction). For this reason, the distortion in the horizontal direction in the virtual image O 'is larger than the distortion in the vertical direction.

In order to cope with such a problem, in this embodiment, an optical system in which the mirrors 3 and 4 and the combiner 2 are combined is used so that the magnification in the horizontal direction is smaller than the magnification in the vertical direction. To That is, since the horizontal dimension of the display surface of the display 5 is originally set to be large, there is no need to forcibly increase the horizontal magnification, and the distortion associated with the high magnification can be reduced. It has.

First, the actual arrangement of the optical system of the vehicle head-up display device 100 shown in FIG. 1 will be described with reference to FIG. Here, FIG. 2A shows the actual arrangement relationship in the vertical direction, and FIG. 2B shows the actual arrangement relationship in the horizontal direction. Here, Av is the distance between the display image Ov on the display 5 in the vertical direction and the combination lens LR composed of the three components of the combiner 2 and the mirrors 3 and 4, and Bv is the distance in front of the windshield WS in the vertical direction. Ah is the distance between the virtual image Ov 'and the combination lens LR, Ah is the distance between the display image Oh on the display 5 and the combination lens LR composed of the three components of the combiner 2 and the mirrors 3 and 4 in the horizontal direction. Is the distance between the virtual image Oh 'in front of the windshield WS in the horizontal direction and the combination lens LR.

As shown in FIGS. 2A and 2B,
The focal lengths of the mirrors 3 and 4 are different in the vertical and horizontal directions so that the actual arrangement relationship between the virtual image O ', the display 5, the mirrors 3 and 4, the combiner 2 and the driver's viewpoint 1 in the vertical and horizontal directions is matched. Designed.

Next, the existence of a solution in the actual arrangement relationship of the optical system shown in FIG. 2 will be described with reference to FIG.

In FIG. 3, a combination lens LR composed of three components of a combiner 2 and mirrors 3 and 4 as an optical system shown in FIG. 2 is represented by an equivalent single lens LW.
3A shows the arrangement in the vertical direction, and FIG. 3B shows the arrangement in the horizontal direction. Note that, in the vertical direction in FIG. 3A and the horizontal direction in FIG. 3B, the display images Ov (Oh) on the display 5 surface,
The arrangement relationship of the equivalent single lens LW with respect to the virtual image Ov '(Oh') and the viewpoint 1 is different. The equivalent single lens LW has a vertical focal length fv and a horizontal focal length fh.
And is different.

First, the optical arrangement relationship between the display image Ov on the display 5 in the vertical direction in FIG. 3A and the virtual image Ov 'in front of the windshield WS is obtained by applying a well-known concave mirror formula. It is expressed by the following equation (1). Here, av is the distance between the display image Ov on the display 5 in the vertical direction and the principal point position Pv of the equivalent single lens LW, and bv is the virtual image Ov 'on the display 5 and the equivalent single lens LW in the vertical direction. , Ah is the distance between the display image Oh on the display 5 in the horizontal direction and the horizontal principal point position Ph of the equivalent single lens LW, and bh is the display in the horizontal direction. The distance between the virtual image Oh 'on the five surfaces and the principal point position Ph of the equivalent single lens LW, and c is the amount of deviation (distance) between the longitudinal principal point position Pv and the lateral principal point position Ph of the equivalent single lens LW. Is shown.

[0017]

1 / av−1 / bv = 1 / (ah + c) −1 / (bh + c) = 1 / fv (1)

The display image Ov and the virtual image O in the vertical direction
The magnification Mv with v 'is represented by the following equation (2).

[0019]

## EQU2 ## Mv = bv / av = (bh + c) / (ah + c)> 1 (2)

The optical arrangement relationship between the display image Oh on the display 5 in the horizontal direction in FIG. 3B and the virtual image Oh ′ in front of the windshield WS is obtained by applying a well-known concave mirror formula. It is expressed by the following equation (3).

[0021]

1 / ah−1 / bh = 1 / fh (3)

The display image Oh and the virtual image O in the horizontal direction
The enlargement ratio Mh with respect to h 'is expressed by the following equation (4).

[0023]

Mh = bh / ah> 1 (4)

The above equations (2) and (4) and the horizontal magnification Mh are smaller than the vertical magnification Mv, ie, M
Since v> Mh, the relationship of the following equation (5) is established.

[0025]

(Bh + c) / (ah + c)> bh / ah> 1 (5) Here, the above equation (5) is satisfied when c <0, and Indicates that a solution exists.

As described above, the vehicular head-up display device 100 of this embodiment has the combiner 2 formed by a part of the inner surface of the windshield WS of the vehicle and the vertical and horizontal dimensions of the virtual image O 'as the target display image. The display 5 has a display surface whose dimension ratio in the horizontal direction is larger than the ratio, and a mirror (lens) disposed between the display 5 and the combiner 2 for projecting image display light from the display surface. And 3) and 4), and an equivalent single lens representing a combination lens LR as an optical system by combining three components of the mirrors 3 and 4 and the combiner 2 between the display 5 and the viewpoint 1 position. LW
Is that the principal point position Pv in the vertical direction is different from the principal point position Ph in the horizontal direction, and the horizontal magnification ratio Mh (= bh / ah) is smaller than the vertical magnification ratio Mv (= bv / av). is there.

Therefore, for example, a square virtual image O 'is used as a target display image as an optical system, and a windshield is placed at the viewpoint 1 position via a combination lens LR composed of three components of mirrors 3, 4 and a combiner 2. To observe in front of the WS, image display light composed of a horizontally long rectangle is projected from the display surface of the display 5. Here, in the combination lens LR whose actual arrangement relationship is the same in the vertical and horizontal directions, the vertical principal point position Pv and the horizontal principal point position Ph are different, and the vertical focal length fv and the horizontal focal point are different. It can be replaced with an equivalent single lens LW having a different distance fh. In this equivalent single lens LW, the horizontal magnification Mh is the vertical magnification Mv.
By making the distance smaller, the focal length fh in the horizontal direction increases, and the F value in the horizontal direction can be increased. This makes it possible to reduce the external dimensions of the mirrors 3 and 4 in the horizontal direction, to suppress the horizontal distortion by using a small display device, to achieve a high magnification, and to improve the display quality and visibility. it can.

In the above embodiment, the mirrors 3 and 4 are optically arranged between the display 5 and the combiner 2 to constitute an optical system in combination with the combiner 2, but the present invention is implemented. In this case, the present invention is not limited to this, and the optical system may be configured by combining the combiner 2 and a concave lens. Further, the number of mirrors (lenses) constituting the optical system can be set as appropriate, and a spherical or aspherical surface (parabolic surface, hyperboloid, etc.) can be employed so as to minimize image distortion in the periphery.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a windshield and an instrument panel around which a head-up display device for a vehicle according to an embodiment of the present invention is applied.

FIG. 2 is an explanatory diagram showing an actual arrangement relationship of an optical system in a vehicular head-up display device according to an example of an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the optical system of FIG. 2 with an equivalent single lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Viewpoint 2 Combiner 3, 4 Mirror (lens) 5 Display 100 Head-up display device for vehicle WS Windshield

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Yujiro Mizuno 14 Iwatani, Shimowasumi-cho, Nishio-shi, Aichi Japan (72) Inventor Toru Mizuno 14th Iwatani, Shimowasumi-cho, Nishio-shi, Aichi (72) Inventor Naoto Kanamori 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (Reference) 3D044 BA03 BA21 BA21 BB01 BC07 BC25 BD01

Claims (1)

[Claims] 1. A combiner comprising a part of an inner surface of a windshield of a vehicle, and a display surface having a lateral dimension ratio that is larger than a target aspect ratio of a display image. A display for projecting image display light from the display surface, and at least one lens disposed between the display and the combiner, wherein the lens and the lens between the display and a viewpoint position; A head-up display device for a vehicle, wherein a principal point of an optical system in combination with a combiner is different between a vertical direction and a horizontal direction, and a horizontal magnification is smaller than a vertical magnification.