JPH06167671A - Display system using hologram - Google Patents

Abstract

PURPOSE:To provide a hologram display system which has a small chromatic aberration and uses two reflection type holograms. CONSTITUTION:This holographic display system features 0.8<(theta2-theta1)/(theta4-theta3)<1.2, where theta1 is the incidence angle of incident light from a light emission display means 1 to a 2nd hologram 2, theta2 the diffraction angle of light diffracted from the 2nd hologram 2 to a 1st hologram 12, theta3 the incidence angle of light which is diffracted by the 2nd hologram 2 and made incident on the 1st hologram 12, and theta4 the incidence angle of light diffracted by the 1st hologram.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display system using a hologram (hereinafter also referred to as a holographic display system), and particularly to a driver such as a vehicle, a vehicle such as a vehicle or an aircraft through a windshield of a vehicle. The present invention relates to a holographic display system that projects necessary information.

[0002]

2. Description of the Related Art A head-up display (hereinafter referred to as HUD) is used as a method of displaying information to a driver in a vehicle.
Has been used recently. This is because the optical information projected from the light emitting display means such as a liquid crystal display device is displayed on a combiner including a half mirror and a hologram provided on the windshield so that the driver hardly moves his or her line of sight from the driving state. The information can be read.

In particular, the one using a hologram as a combiner is capable of diffracting optical information toward a driver and forming an image at an arbitrary position, and it is possible to enhance the brightness without impairing the foreground brightness. It is effective as a combiner for HUD because it has a characteristic that a display virtual image of brightness can be obtained.

However, since such a hologram is exposed by two-direction light emitted from a point light source, a virtual display image (optical information of a light emitting display means having a finite size formed by the hologram ( Aberrations related to blurring and distortion occur especially at the edges of the
As a result, a sufficient display image could not be obtained.

Therefore, as disclosed in US Pat. No. 4,218,111, an aberration relating to image blurring and distortion generated in a reflection hologram is relayed between a CRT as a display means and the reflection hologram. A display system has been proposed in which the chromatic aberration is reduced by removing the chromatic aberration by using the narrow band CRT having the wavelength as the display means.

Further, in Japanese Patent Laid-Open No. 62-94816, the aberration caused by the reflection hologram is removed by providing two holographic optical elements between the display screen as the display means and the reflection hologram. A system is disclosed.

In Japanese Laid-Open Patent Publication No. 61-278820, one holographic optical element is provided between the display screen and the reflective hologram to prevent aberrations associated with image blurring and distortion caused by the reflective hologram. A system for correcting with the shape of a reflective or transmissive surface is shown.

[0008]

In the holographic display system, it is desirable that the display virtual image has little blurring and distortion, and that chromatic aberration is sufficiently removed. When it is mounted on a vehicle or the like, Considering the space of those vehicles, it is desirable that the vehicle be small and have a simple structure.

However, US Pat. No. 4,218,1
The display system disclosed in No. 11 uses an optical system composed of a plurality of lenses to reduce aberrations associated with blurring and distortion of a display virtual image, and needs to use a narrow band CRT for chromatic aberrations. It is difficult to reduce the weight and size, and it is expensive.

Further, the display system disclosed in Japanese Patent Laid-Open No. Sho 62-94816 uses three hologram optical elements in total, though it is improved in weight reduction and downsizing of the system, so that the light utilization efficiency is high. It had the drawback of not being.

Further, the above-mentioned method and JP-A-61-27
According to the system disclosed in Japanese Patent No. 8820, although the aberration related to the blur and distortion of the display virtual image is reduced,
In order to reduce the chromatic aberration of the display virtual image, the light emitting display means had to have a narrow wavelength band.

Further, Japanese Patent Laid-Open No. 61-35416 discloses a holographic image in which two reflective holograms having the same geometrical structure are arranged in order to eliminate chromatic aberration caused by the dispersion characteristic of the reflective hologram. Although a display system is disclosed and it is possible to reduce chromatic aberration, there is a limit to the arrangement of the two, and especially when one hologram is provided on the windshield of a vehicle or the like, the other hologram can be freely arranged. Has the drawback that the degree of freedom and the degree of freedom in the arrangement of the light emitting display means are limited, and therefore,
It was not possible to arrange these holograms at desired positions to reduce the blurring and distortion of the display virtual image.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a new holographic display system which has not been known in the past.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a light emitting display means for generating a light ray containing information, and the light ray is diffractively reflected toward an observer. A second reflection hologram disposed between the first reflection hologram and the light emitting display means and the first reflection hologram, and diffracting a light beam from the light emission display means toward the first reflection hologram. In a display system using a hologram, which comprises at least a reflection hologram and allows a viewer to visually recognize a display virtual image of the light emitting display means, a light beam from the light emitting display means is directed toward the center of the second reflection hologram. Incident incident angle θ ₁ and the center of the second reflection hologram to the center of the first reflection hologram of the diffracted light diffracted from the second reflection hologram to the first reflection hologram Angle θ ₂ to the first reflection type hologram and the incident angle θ of the incident light diffracted from the second reflection type hologram and incident on the first reflection type hologram from the center of the second reflection type hologram to the center of the first reflection type hologram. ₃ and the diffraction angle θ ₄ from the center of the first reflective hologram of the display virtual image diffracted by the first reflective hologram and visually recognized by the observer,
The present invention provides a display system using a hologram characterized by satisfying the relationship of 0.8 <(θ ₂ −θ ₁ ) / (θ ₄ −θ ₃ ) <1.2.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing an example of a holographic display system of the present invention. The light emitting display means 1 and the second reflection type hologram 2 have an incident angle θ _{1 at} which a light ray containing information emitted from the light emitting display means 1 is incident on the reflection type hologram, and this light ray is the second reflection type hologram. The distance s _{1 is set} so that the diffraction angle of the diffracted light diffracted from the hologram is θ _2.
Are arranged at intervals.

The first reflection type hologram 12 has an incident angle of θ ₃ at which the diffracted light diffracted by the second reflection type hologram 2 enters, and is diffracted by the first reflection type hologram 12 so that the observer 10 can see it. The display virtual image 3 to be visually recognized is arranged so that the diffraction angle from the center of the first reflection type hologram 12 is θ _4, and the observer 10 is on an extension line between the display virtual image 3 and the first reflection type hologram 12. The display virtual image 3 is visually recognized.

The first reflection hologram 12 and the second reflection hologram 12
Of the first reflection type hologram 12 and the display virtual image formed by the first reflection type hologram 12 are separated by a distance s ₂ from the first reflection type hologram 12.
Is formed at the position.

FIG. 2 is a conceptual diagram showing an example of an exposure method for producing a reflection type hologram of the present invention, in which a point light source 41 is provided at a position separated from the hologram photosensitive material 21 by a distance of R ₁ and R _2. The spherical wave exposure is performed from both surfaces of the hologram photosensitive material 21 at incident angles of α ₁ and α ₂ , respectively.

FIG. 3 is a conceptual diagram for explaining chromatic aberration of a holographic display system in which two reflection holograms are arranged. Light rays of wavelengths λ and λ + Δλ emitted from the same point on the light emitting display surface of the light emitting display means 1 are diffracted by the second reflective hologram 2 and then travel toward the viewer through different paths due to dispersion. Therefore, the direction of the ray toward the observer 10 is extended in the opposite direction, and the coordinates of the arrival point of the ray of wavelength λ + Δλ to the display virtual image 3 plane are (x ′, y ′), and the display virtual image of the wavelength λ 3 plane When the coordinates of the reaching point are set to (x, y), the distance between these two coordinates becomes chromatic aberration and is visually recognized by the observer 10.

Here, the two reflection holograms are described above (see FIG. 1), 0.8 <(θ ₂ −θ ₁ ) / (θ ₄ −θ
₃ ) By arranging them so that <1.2, it is possible to reduce the distance between the points (x, y) and (x ', y'), and to adjust the diffraction direction of the reflection hologram depending on the wavelength. The shift, that is, the chromatic aberration will be reduced.

FIG. 4 is a conceptual diagram showing another example of the holographic display system of the present invention. A converging optical system 5 for refracting the light beam from the light emitting display means 1 is interposed between the light emitting display means 1 and the second reflection hologram 2.
As the converging optical system 5, for example, a single lens or a double-sided aspherical single lens is used, and the distance between the light emitting display means 1 and the second reflection hologram 2 can be shortened as compared with FIG. This distance can be secured according to the space of the vehicle or the like equipped with the holographic display system of the present invention.

FIG. 5 is a conceptual diagram showing another example of the holographic display system of the present invention. A converging optical system 6 for reflecting the light beam from the light emitting display means 1 is interposed between the light emitting display means 1 and the second reflection hologram 2.
As the converging optical system 6, for example, a reflective concave mirror or the like is used, and the distance between the light emitting display means 1 and the reflection hologram 2 can be shortened as compared with FIG. 1, and the holographic display system according to the present invention is provided. This distance can be secured according to the space of the vehicle or the like.

Here, a case where the holographic display system according to the present invention is mounted on a vehicle will be described.

FIG. 6 is a conceptual view of the holographic display system according to the present invention mounted on a vehicle. A light emitting display means is provided below a windshield 61 of the vehicle. The light emitting display means is a light source 62. The light emitted from passes through the display body 63 and emits information to be displayed as light rays. The windshield 61 of the vehicle body is provided with the first reflection type hologram 12, and the light beam from the light emitting display means is applied to the second reflection type hologram 2 and diffracted toward the first reflection type hologram 12. The display virtual image is visually recognized at the observation position of the observer 10.

The information to be displayed in the present invention is appropriately selected according to its display application, and examples thereof include a vehicle speedometer, a tachometer, and various warning lamps. The display distance can be set according to the urgency or need of the. The observer is mainly a driver of the vehicle, but can also include passengers other than the passenger seat, and all these persons.

The reflection type hologram usually has an area of several tens of mm square to several hundreds of mm square and a thickness of several tens of μm, and has a light diffraction function. As the reflection hologram, a so-called reflection hologram such as an emboss type or a Lippmann type hologram can be widely used. As the reflective hologram material, various photosensitive materials such as polyvinylcarbazole, gelatin dichromate, photoresist, photopolymer, and silver salt can be used.

When the windshield is provided with the first reflection hologram, for example, the surface of the windshield (the outer surface of the vehicle).
Although it may be provided on the inner surface of the vehicle, it is preferable to use it by enclosing it in the windshield, which is a laminated glass, particularly in view of protection of the reflection hologram.

The light emitting display means in the present invention has a function of emitting light to display, and a hot cathode tube (HC) is attached to a display body composed of a so-called light receiving display element such as a liquid crystal display element.
T), a fluorescent display tube (VF), a halogen lamp, an LED, or the like, which emits light emitted from a light source, or may have these functions together.

As the liquid crystal display element, a transmission type twisted nematic type liquid crystal display element, a super twisted nematic type liquid crystal display element and the like can be preferably used. Also,
Apart from that, instead of using the light receiving display element, the light source itself may be patterned and arranged to generate specific information as light. In the case where the light source is used together with the light receiving display element, an appropriate light beam collimating means such as a lens system or an appropriate light guiding means such as a light guide plate is arranged between the light receiving display element and the light source. Good.

[0030]

In the HUD using the reflection hologram, since the reflection hologram is provided on the windshield of a vehicle or the like, the angle at which the reflection hologram is arranged is limited (same as the angle of the windshield). Therefore, the position where the light emitting display means is provided is also restricted, and various restrictions are caused in the system configuration.

Therefore, in the holographic display system of the present invention, by using two reflection holograms, even if the angle of the first reflection hologram provided on the windshield is limited, the reflection hologram of the second reflection hologram can be changed. By adjusting the angle, it is possible to reduce the chromatic aberration of the display virtual image.

Further, in the present invention, the exposure distance from the point light source at the time of exposure is optimized, and the positions where the respective reflection holograms are arranged are appropriately determined. It can be reduced without sacrificing the reduction of chromatic aberration.

[0033]

【Example】

(Example 1) By the exposure method shown in FIG. 2, α ₁ = 4
0.0 °, α ₂ = 60.0 °, R ₁ = 575.7 mm,
The hologram photosensitive material was exposed with R ₂ = 494.0 mm to form a first reflection hologram, and α ₁ = 50.0
°, α ₂ = 66.2 °, R ₁ = 501.3 mm, R ₂ =
The hologram photosensitive material was exposed to 466.8 mm to form a second reflection hologram.

2 created under such exposure conditions
As shown in FIG. 1, one reflection hologram has s ₁ = 5
00 mm, d = 120 mm, s ₂ = 500 mm, θ ₁ =
66.2, θ ₂ = 50.0, θ ₃ = 40.0, θ ₄ = 6
To be 0.0 ((θ ₂ −θ ₁ ) / (θ ₄ −θ ₃ ))
= 0.81), respectively.

The two kinds of wavelengths 545 nm and 535 nm contained in the light beam emitted from the point (0, 0) of the coordinates shown in FIG. 3 of the light emitting display means are (0, 0) on the coordinates of the display virtual image. 0) and (0, 0.003) (unit mm), respectively, the difference between the two points is only 0.003 mm, and 0.8 <(θ ₂ −θ ₁ ) / (θ ₄ −θ ₃ ). <1.2
By doing so, it was possible to reduce the chromatic aberration of the holographic display system using the two reflection holograms.

(Embodiment 2) FIG. 7 is a conceptual diagram showing another example of the holographic display system of the present invention, in which the light emitting display means 1 is arranged above the observer 10.

According to the exposure method shown in FIG. 2, α ₁ = 5
0.0 °, α ₂ = 70.0 °, R ₁ = 978.0 mm,
The hologram photosensitive material was exposed with R ₂ = 987.0 mm to form a first reflection hologram, and α ₁ = 12.0
°, α ₂ = 28.6 °, R ₁ = 777.6 mm, R ₂ =
The hologram photosensitive material was exposed to 907.6 mm to form a second reflection hologram.

2 created under such exposure conditions
As shown in FIG. 7, one reflection hologram has s ₁ = 1
000 mm, d = 120 mm, s ₂ = 750 mm, θ ₁
= 12.0, θ ₂ = 28.6, θ ₃ = 50.0, θ ₄ =
To be 70.0 ((θ ₂ −θ ₁ ) / (θ ₄ −θ
₃ ) = 0.83), respectively.

The two kinds of wavelengths 545 nm and 535 nm contained in the light beam emitted from the point (0, 0) of the coordinates shown in FIG. 3 of the light emitting display means are (0, 0) on the coordinates of the display virtual image. 0) and (0, -0.002) (unit mm), respectively, the difference between the two points is only 0.002 mm, and 0.8 <(θ ₂ −θ ₁ ) / (θ ₄ −θ ₃ ) <1.2
By doing so, it was possible to reduce the chromatic aberration of the holographic display system using the two reflection holograms.

[0040]

According to the holographic display system of the present invention, by using two reflection holograms, for example, the first hologram is used.
When the arrangement and angle of the first reflection type hologram are limited due to the fact that the reflection type hologram of 1 is provided in windshield glass of a vehicle or the like, a certain degree of freedom is given to the angle of the second reflection type hologram. Therefore, it is possible to remove the strict restriction on the arrangement of these reflection holograms and the arrangement of the light emitting display means, and it is possible to reduce the chromatic aberration that occurs when two reflection holograms are used.

Further, in the present invention, the exposure distance from the point light source at the time of exposure is optimized, and the positions where the respective reflection holograms are arranged are appropriately determined, thereby displaying a virtual image without sacrificing reduction of chromatic aberration. It is possible to reduce aberrations associated with blurring and distortion, and it is not always necessary to use a narrow band light emitting display means, and a holographic display system that is inexpensive, simplified and downsized with only two reflection holograms. The aberration can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a holographic display system of the present invention.

FIG. 2 is a conceptual diagram showing an example of an exposure method for producing a reflection hologram of the present invention.

FIG. 3 is a conceptual diagram illustrating chromatic aberration of a holographic display system in which two reflective holograms are arranged.

FIG. 4 is a conceptual diagram showing an example of a holographic display system of the present invention.

FIG. 5 is a conceptual diagram showing an example of a holographic display system of the present invention.

FIG. 6 is a conceptual diagram showing an example in which the holographic display system of the present invention is installed in a vehicle.

FIG. 7 is a conceptual diagram showing an example of a holographic display system of the present invention.

[Explanation of symbols]

 1: Light emitting display means 2: Second reflection type hologram 3: Display virtual image 5, 6: Converging optical system 10: Observer 12: First reflection type hologram 21: Hologram photosensitive material 41: Point light source 61: Windshield 62 : Light source 63: Display

Claims (5)

[Claims] 1. A light emitting display means for generating a light ray containing information, a first reflection type hologram arranged so as to reflectively diffract the light ray toward an observer, the light emitting display means, and a first light emitting display means. And a second reflection hologram for diffracting the light beam from the light emission display means toward the first reflection hologram, and the observer visually recognizes the virtual display image of the light emission display means. In the display system using the hologram, the incident angle θ _{1 at} which the light beam from the light emitting display unit is incident toward the center of the second reflective hologram and the first reflective type from the second reflective hologram. a diffraction angle theta ₂ to the first reflection hologram center from the second reflection hologram center of the diffracted light is diffracted toward the hologram, the first reflection is diffracted from the second reflection hologram The incident angle theta ₃ from the second reflection hologram center of light incident on the hologram to the first reflection hologram center, the virtual display image that the observer is diffracted from the first reflection hologram is visible first The hologram is characterized in that the diffraction angle θ ₄ from the center of the reflection type hologram satisfies the relationship of 0.8 <(θ ₂ −θ ₁ ) / (θ ₄ −θ ₃ ) <1.2. The display system was. 2. A converging optical system is arranged between the light emitting display means and the second reflection hologram, and the light emitting display means is located between the converging optical system and the focal point of the converging optical system. A display system using the hologram according to claim 1. 3. A display system using a hologram according to claim 2, wherein the converging optical system is a single lens. 4. A display system using a hologram according to claim 2, wherein the converging optical system is a double-sided aspherical single lens. 5. A display system using a hologram according to claim 2, wherein the converging optical system is a reflecting concave mirror.