JPH0436789A - Holographic display system for vehicle - Google Patents

Abstract

PURPOSE:To reduce the blur of a display image due to the influence of a chromatic aberration by guiding diffracted light from a reflection type hologram diffraction grating to a driver so that a virtual image luminously displayed by a luminous display means can be observed on the back of the grating. CONSTITUTION:When a luminous display device 1 consisting of a fluorescent display tube and arranged on a ceiling 9 luminously displays an image, its vidual light is transmitted through a translucent type hologram diffraction grating 3 and made incident upon the reflection type hologram diffraction grating 2. Thereby, the luminous display of the display device 1 is projected to the grating 2 and the virtual image displayed on the display device 1 is formed in the front of a front glass 4 arranged on the back of the grating 2. Consequently, a driver driving a vehicle while observing an exterior through the glass 4 can observe the virtual image superposed to the exterior within his (or her) visual field.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a holographic display system for use in a vehicle.
More specifically, the present invention relates to a vehicle-mounted holographic display system that includes means for reducing blurring of a displayed image due to the influence of chromatic aberration.

[Prior art and problems to be solved by the invention] Conventionally, as this type of system, for example, US Pat. No. 4,218
There is one shown in No. 111. The system shown in this patent uses a relay lens system, a narrowband high-brightness CRT, etc. to minimize the influence of aberrations on the displayed image obtained by projecting the CRT display onto a reflective hologram diffraction grating. ing. For this reason, the optical system becomes complicated, making it difficult to reduce the weight and size of the optical system, and there are other problems such as the inefficient use of light and the high cost of the system.

Therefore, a hydrographic display system for vehicles that solves these problems has been proposed in Japanese Patent Application Laid-Open No. 61-35416. This proposed system corrects chromatic aberration by arranging two reflective hologram diffraction gratings, which are manufactured under the same conditions, facing each other.

In this proposal, a display device and one reflection hologram diffraction grating that diffracts and reflects visible light from the display device to the other reflection hologram diffraction grating are placed inside the dash board, and one reflection hologram diffraction grating is placed inside the dashboard. The other reflective hologram diffraction grating is disposed above the dash board, which ultimately diffracts and reflects the visible light diffracted and reflected by the grating toward the driver.

By arranging a display device and a reflection hologram diffraction grating that diffracts and reflects visible light from the display device in the direction of the reflection hologram diffraction grating on the dash mode in this way, many devices can be built-in. There are also problems in that the placement within the dash board is difficult, and it is difficult to mount it on a vehicle, and it is impossible to mount it on an existing vehicle.

In view of the above-mentioned conventional problems, the present invention has been developed to provide an in-vehicle device that can correct chromatic aberration, can be easily installed in a vehicle, and can also be installed in existing vehicles. The purpose is to provide a holographic display system.

[Means for solving problems]

In order to achieve the above object, the in-vehicle holographic display system according to the present invention includes a light-emitting display means arranged on the ceiling of a vehicle and generating visible light; a transmission hologram diffraction grating that transparently diffracts the visible light, and a reflection hologram diffraction grating that is disposed above the dashboard and reflectively diffracts the visible light that has been transparently diffracted by the transmission hologram diffraction grating. The device is characterized in that the diffracted light from the reflection hologram diffraction grating is guided toward the driver, so that a virtual image of the light emission display by the light emission display means can be visually recognized behind the reflection hologram diffraction grating.

[For production]

In the above configuration, the light emitting display means and the transmission hologram diffraction grating are arranged on the ceiling of the vehicle.

This transmission type hologram diffraction grating transparently diffracts the visible light from the light emitting display means on the ceiling, and the visible light that has been transparently diffracted by the transmission type hologram diffraction grating is reflected by the reflection type hologram diffraction grating placed on the dash board. The diffracted light from the reflective hologram diffraction grating is guided toward the driver, so that a virtual image of the light emitting display by the light emitting display means can be visually recognized behind the reflective hologram diffraction grating.

In this way, the visible light from the light-emitting display means is transmitted through the transmission hologram diffraction grating and projected onto the reflection hologram, so the broadband visible light is ultimately mixed up by differences in diffraction angles, causing the driver to They now travel on the same straight line toward the eye, and chromatic aberration is corrected.

Furthermore, since the light-emitting display means and the transmission type hologram diffraction grating are arranged on the ceiling, there is no need to arrange any members inside the dash board, which has many restrictions.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

Figure 1 shows an in-vehicle rad-up display device (HUD) implementing the in-vehicle holographic system according to the present invention.
In the figure, 1 is a light emitting display such as a fluorescent display tube (VFD) usually mounted on a vehicle, 2 is a reflective hologram diffraction grating, 3 is a transmission hologram diffraction grating, 4 is a windshield, 5 is the Datsush board;
The light emitting display 1 and the transmission type hologram diffraction grating 3 are arranged on the ceiling 9 of the vehicle interior, and the reflection type hologram diffraction grating 2 is provided on the dash board 5 on the vehicle interior side of the windshield 4 by appropriate means.

When the light-emitting display 1 performs a light-emitting display, visible light from there passes through the transmission type hologram diffraction grating 3 and enters the reflection-type hologram diffraction grating 2. is projected onto the reflective hologram diffraction grating 2, and a display virtual image 1' of the light emitting display 1 is formed in front of the windshield 4 behind the reflective hologram diffraction grating 2.

Therefore, a driver driving while looking at the outside view through the windshield 4 can see the virtual image 1' superimposed on the outside view within his field of view.

In addition, in the figure, the angle θ8. θ! , distance LI, L, t, L4
is determined by the position of the driver's eyes 6, the position of the virtual image 1', etc.

Before explaining the operation of the in-vehicle hydrographic display system having the above configuration, the manner in which a displayed image is blurred due to the chromatic aberration of the reflective hologram diffraction grating 2 will be discussed with reference to FIG. Figure 2 shows one point 1a on the light emitting display.
visible light from the center wavelength of the emission spectrum λ. and three types of wavelength λ with half width 2Δλ. ,λ. +Δλ,λ. It is shown by a ray trace represented by the light of -Δλ,
A virtual image 1a of a point 1a is placed in front of the reflection hologram diffraction grating 2.
' are formed. Of course, the illustration is exaggerated and they are actually much closer together, but due to the chromatic aberration mentioned above, the displayed image appears blurred.

FIG. 3 shows how the above-mentioned chromatic aberration is corrected by the system of the present invention and the blur is reduced. In FIG. light λ. +Δλo1λ. ,λ.

-Δλ finally cancels out the difference in diffraction angle due to the reflection hologram diffraction grating 2 and travels on the same line toward the driver's eyes 6, so the virtual image 1a' of point 1a can be visually recognized as almost a point. .

4 and 5 respectively show the positional relationship between the light source 7 and the hologram dry plate 8 when producing the reflection hologram diffraction grating 2 and the transmission hologram diffraction grating 3 used in the system of the present invention.

In either case, the hologram dry plate 8 is exposed to irradiation with two spherical diverging lights, and interference fringes are recorded to form a diffraction grating.
The latter differs in that it is illuminated from only one side.

In Figures 4 and 5, distance! L is the distance from the position where you want the center of the virtual image to be visible during use to the center of the reflection hologram diffraction grating 2, distance L! and angle θ1 are the approximate distance and direction from the center of the reflection hologram diffraction grating 2 to the center of the transmission hologram diffraction grating 3 when in use, and the distance L4 is the approximate distance and direction from the center of the light emitting display 1 to the center of the transmission hologram diffraction grating when in use. Each distance is determined corresponding to the distance to the center of the grid 3. Although there is no absolute restriction on determining the distance lit and the angle θf, they are related to the position of the light emitting display 1 and the position of the transmission hologram diffraction grating 3 during use, and these are important to avoid blurring of the displayed image. It is subtly related to the condition.

Since the light emitting display 1 and the transmission hologram diffraction grating 3 are arranged on the ceiling of the vehicle as in the above configuration, various instruments and devices are installed in the dash board 5 of the vehicle. This is effective when there is no room to provide the transmission hologram diffraction grating 3, and it is also effective when the system is mounted on an existing vehicle.

〔effect〕

According to the present invention described above, aberrations can be corrected accurately simply by providing a transmission type hologram diffraction grating between the light emitting display and the reflection type hologram diffraction grating, so that the projected image onto the reflection type hologram diffraction grating is The image is clear even without the use of a system, and a bright image can be projected using a broadband light emitting display.

In particular, since the light emitting display means and the transmission hologram diffraction grating are placed on the ceiling, there is no need to place any components inside the dash board, which has many restrictions, making it easy to mount it on the vehicle. Moreover, it will also be possible to implement it into existing vehicles.

In addition, a transmission hologram diffraction grating is used to correct aberrations, and correction is performed by transparent diffraction of visible light.
There are no restrictions on the degree of freedom in the arrangement position of the light emitting display with respect to the reflection hologram, and the transmission hologram diffraction grating can be manufactured easily and mass-produced.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the in-vehicle holographic display system according to the present invention, Fig. 2 is a diagram for explaining blurring of a displayed image due to chromatic aberration, and Fig. 3 is a diagram showing how to correct chromatic aberration according to the present invention. FIG. 4 is a diagram showing how to manufacture a reflection type hologram diffraction grating, and FIG. 5 is a diagram showing how to manufacture a transmission type hologram diffraction grating. DESCRIPTION OF SYMBOLS 1... Light emitting display, 1'... Virtual image, 2... Reflection type hologram diffraction grating, 3... Transmission type hologram diffraction grating, 5... Dash board, 6... Driver's eyes, 9
···ceiling.

Claims (1)

[Scope of Claims] A light-emitting display means arranged on the ceiling of a vehicle and generating visible light; a transmission hologram diffraction grating arranged on the ceiling and transparently diffracting the visible light from the light-emitting display means; a reflection hologram diffraction grating that is disposed above the dashboard and reflectively diffracts the visible light that has been transparently diffracted by the transmission hologram diffraction grating; A vehicle-mounted holographic display system, characterized in that the virtual image of the light emitting display by the light emitting display means can be visually recognized behind the reflection type hologram diffraction grating.