JPH04353033A - Head-up display for vehicle - Google Patents

Abstract

PURPOSE:To eliminate a strained regenerated image resulting from the inclination of a glass plate where a holographic combiner is installed, and change the magnification of the image arbitrarily. CONSTITUTION:When the beams from a luminous indicator placed near a glass surface go into a hologram 20 with width A, the beams scattered a little by the hologram 20 are reflected and diffracted, and are displayed in a driver's view 11 with width C.

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 (HUD) for a vehicle.

0002

2. Description of the Related Art HUDs have recently come into use as a method of displaying information to drivers and the like inside a vehicle. This system projects optical information projected from a light-emitting display means such as a liquid crystal display onto a combiner such as a half mirror, allowing the driver to read the information without having to move his or her eyes while driving. .

Recently, the above-mentioned combiner has been used because of its simplicity as an optical element and the richness of added functions.
Holograms are gaining attention. This holographic combiner has not only a reflection function (diffraction function) but also a lens function, so it can diffract optical information in the direction of the driver's field of vision, or it can be used to incorporate other optical systems such as lenses. It becomes possible to form an image at any position without using it. Another feature is that a high-brightness display image can be obtained without impairing foreground brightness.

FIG. 5 is a conceptual diagram showing the structure of such an in-vehicle HUD. Here, 31 is the observation position of the driver, 32 is a holographic combiner, 33 is a light beam containing information, 34 is a lens system that is a collimator, 35 is a transmission type liquid crystal display element that is a display body, 36 is a halogen lamp, etc. 37 is a windshield, and 38 is a vehicle body.

The light emitted from the light source 36 passes through a transmission type liquid crystal display element 35 via a lens system 34, and then passes through a holographic combiner 32 provided in a windshield 37 of the vehicle.
is reflected (diffracted) and presented to the driver at observation position 31.
is visible.

[0006]

[Problem to be solved by the invention] However, such HU
In D, it is preferable to use the hologram attached to the windshield surface because it becomes compact, but in such a case, the magnification of the reproduced display image may change due to the tilt of the windshield.

That is, in FIG. 5, a light beam 33 containing information incident with a width A is
2 and exits with a width B, and the driver's field of view 3
It is displayed on 1. At this time, if the light source 36 is located almost directly below the holographic combiner 32, the driver's field of view 31 is slightly above the holographic combiner 32, and the windshield 37 is tilted approximately 30 degrees from the horizontal, the tilt of the hologram surface with respect to the light beam will cause reproduction. The image will be reduced by approximately 40%.

FIG. 2 shows a conventional example of such a hologram recording method for a display. A reference beam 9 as a plane wave and an object beam 10 as a plane wave are each irradiated with a single wavelength laser beam onto a photosensitive material 8 for forming a hologram, and the photosensitive material 8 is exposed.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a novel vehicle-mounted head-up display that has not been previously known. It is.

0010

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a light-emitting display means that generates information to be displayed as a light beam, and a light-emitting display means that is attached to the windshield of an automobile. A head-up display for a vehicle, comprising a reflective first hologram that diffracts light beams toward a viewer, wherein the display is located between the light-emitting display means and the first hologram, and is located between the light-emitting display means and the first hologram, and is regenerated by the tilt of the windshield. For a vehicle, comprising a second hologram of a transmission type that diffracts a light beam containing information to be displayed so as to be incident on the first hologram so as to offset a change in magnification of a display image. It provides a head-up display.

[0011] The information to be displayed here is appropriately selected depending on its display purpose, and examples include a vehicle speedometer and tachometer.

[0012] The viewer is mainly a vehicle driver,
In addition, passengers in the front passenger seat, other passengers, and all of these can also be targeted.

[0013] The hologram functions as a combiner for the HUD. It usually has an area of several tens to several hundred mm square, a thickness of several tens of micrometers, and has a light diffraction function. As this hologram, not only the embossed type that is widely used at present, but also Lippmann type, rainbow type, and other so-called holograms can be widely used. In addition, as a hologram material,
Various photosensitive materials such as polyvinyl cabazole, dichromate gelatin, photoresist, photopolymer, and silver salt can be used.

The peak wavelength of the diffraction intensity of the hologram can be made to substantially match the peak wavelength of the intensity of the light source,
This is preferable in terms of increasing diffraction efficiency. Further, the hologram may be formed by performing multiple exposures with light having different properties.

[0015] The holographic combiner made of such holograms may be provided separately from the windshield, but due to its simple structure, it is preferably used by being attached to the windshield of a vehicle, especially from the viewpoint of protecting the hologram. is preferably used by being sealed inside a windshield glass that is laminated glass. In the present invention, two types of holograms are used, and both of them may be enclosed in the windshield, or only the hologram that diffracts light toward the viewer may be enclosed.

In this case, the laminated glass is made by laminating and adhering a synthetic resin film such as a polyvinyl butyral film or a polyurethane film to at least one sheet of glass. Examples include glass plate/synthetic resin film/glass plate, glass plate/synthetic resin film/glass plate/synthetic resin film, and glass plate/synthetic resin film/synthetic resin film. The hologram may be encapsulated at the boundary of these glass plates or synthetic resin films or inside the synthetic resin film. The glass plate on which the hologram is mounted may be colored, or may have a heat ray reflective film or the like provided on its surface.

The light-emitting display means of the present invention has a function of emitting light to display a display, and representative examples thereof include:
Hot cathode tubes (
HCT), fluorescent display tube (VF), tungsten lamp,
Some use light sources such as halogen lamps and LEDs. As this liquid crystal display element, a transmission type twisted nematic type liquid crystal display element, a super twisted nematic type liquid crystal display element, etc. can be preferably used. Alternatively, the light sources themselves may be patterned and arranged to generate specific information as light without using a light-receiving display element. In the case of a light-receiving type display element that uses the above-mentioned light source in combination, an appropriate light beam collimating means such as a lens system, or an appropriate light-guiding means such as a light guide plate may be placed between the light-receiving type display element and the light source. good.

Furthermore, in the optical path until the light is projected onto the holographic combiner, optical deflection means such as a mirror, or KNbO3, β-BaB
A nonlinear optical element made of 2O4, KTiOPO4, KH2PO4, etc. may be arranged.

In the present invention, when the light beam containing the information to be displayed is incident on the first reflection type hologram, the transmission type first hologram is set so as to cancel out the change in magnification of the reproduced display image caused by the tilt of the windshield. It is characterized by having two holograms. That is, by providing the second hologram with a function of diverging or converging the light flux at an appropriate spread angle, the above-mentioned change in magnification is prevented.

Specifically, when the width of the light beam diffracted by the first reflection hologram is smaller than that before being diffracted, the first reflection hologram
A second hologram of a transmission type is placed in front of the hologram, and the light beam is slightly spread before it is incident on the first hologram. Conversely, if the width of the light beam diffracted by the first reflection hologram is larger than before diffracted, a second transmission hologram that narrows the light beam slightly is placed in front of the first hologram.

By doing this, distortion of the reproduced image due to the inclination of the glass plate on which the holographic combiner is mounted can be eliminated, and the luminous flux of the second hologram can be diverged or converged at an appropriate spread angle. By adjusting , the image magnification can be changed arbitrarily.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a holographic combiner section showing an embodiment of the present invention. The windshield glass is a laminated glass made of two glass plates, and 17 is an inner glass plate, 18 is an outer glass plate, and 19 is an interlayer film. Here, a hologram mirror consisting of a combination of two holograms 20 and 21 is enclosed in the inner surface of the laminated glass, and 20 is a transmission hologram (second hologram), which is placed on the side of the inner glass 17. Further, a reflection hologram 21 (first hologram) is arranged on the side of the outer glass 18 facing thereto.

As shown in FIG. 1, when a light beam from a light emitting display placed near the glass surface is incident with a width A at an angle of 30 degrees to the normal direction of the hologram surface, the light beam enters the hologram 20. If the function of diverging and converging is not provided, the light beam transmitted and diffracted by the hologram 20 in the normal direction of the hologram 21 is reflected and diffracted by the hologram 21 at an angle of 60 degrees with respect to the normal direction of the hologram surface, as shown by the broken line. The width becomes B as shown in FIG. At this time, since the hologram surface is tilted with respect to the light beam, the reproduced image is reduced by about 40% due to the tilt.

In order to prevent such a change in magnification, these two holograms were manufactured as follows. Figure 3 shows the exposure method for producing each of these holograms.
, shown in Figure 4.

First, in order to create the transmission hologram 20, as shown in FIG. 3, a reference beam 12 forming a plane wave from the same side of the photosensitive material 11 at a predetermined angle, and an object beam 13 forming a diverging spherical wave.
The photosensitive material 11 is simultaneously irradiated with light and exposed.

Furthermore, as shown in FIG. 4, a reflection hologram 2
1, reference light 1 forming a diverging spherical wave is used as a reference light.
5 and object light 16 in the form of a plane wave are simultaneously irradiated onto the photosensitive material 14 for exposure.

By using the hologram manufactured in this way as a combiner, the light beam in FIG. 1 will be expanded after passing through the second hologram, as shown by the solid line, and the beam can be adjusted so that A=C. becomes possible.

It should be noted that it is easier and more advantageous to attach holograms to two glass plates as shown in FIG. This is desirable for obtaining a clear image because the number of passes is reduced.

[0029]

According to the present invention, it is possible to eliminate the distortion of a reproduced image caused by the inclination of the glass plate on which the holographic combiner is attached, and also to be able to arbitrarily change the image magnification.

[Brief explanation of drawings]

[Figure 1] Cross-sectional view showing the basic configuration of the present invention

[Figure 2]
Conceptual diagram showing the conventional exposure method for producing holograms

[Figure 3] Conceptual diagram showing the exposure method when producing a hologram of the present invention

[Figure 4] Conceptual diagram showing the exposure method during hologram production of the present invention

[Figure 5] Conceptual diagram showing a conventional holographic head-up display

[Explanation of symbols]

17 Inner plate glass 18 External glass 19 Intermediate film 20 Transmission hologram 21 Reflection hologram 22 Driver field of view

Claims (1)

[Claims] 1. A first hologram of a reflective type that is attached to a windshield of an automobile and that diffracts the light beam toward a viewer. In the head-up display for a vehicle, a light beam containing information to be displayed is emitted between the light-emitting display means and the first hologram so as to offset a change in the magnification of the reproduced display image caused by the tilt of the windshield. A head-up display for a vehicle, comprising a transmission type second hologram that diffracts the light beam so as to be incident on the first hologram.