JPH1191402A - Vehicular holographic display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular holographic display system which does not generate the flare light and whose visual area is wide and which doed not cause longitudinal directional contraction of an image and image distortion. SOLUTION: The information containing light 3 irradiated at an incident angle θi to a hologram 2 arranged in a dark color concealing part 11 of windshield glass 7 through a prism 30 from an information display source having a display body 5 having an inclination to the optical axis, is diffracted at an angle θd (≠ θi) of diffraction by the hologram 2, and a display image 10 is visually confirmed by an observer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic display system for a vehicle for projecting information necessary for an observer in a vehicle, and more particularly to a holographic display system for a vehicle having no flare light and a wide viewing area. .

[0002]

2. Description of the Related Art In recent years, as a method of displaying information to a driver of a vehicle such as an automobile, a display device such as a head-up display (hereinafter, referred to as HUD) has been used. In this method, optical information projected from an information projection unit such as a liquid crystal display device is projected on a combiner including a half mirror or a hologram incorporated in a windshield of an automobile or the like, and a driver almost moves a viewpoint from a driving state. This allows information to be read without the need.

In particular, a hologram as a combiner can have a function of diffracting optical information toward a driver and also have a lens function, so that the optical information can be diffracted in the direction of the driver's field of view. Alternatively, an image can be formed at an arbitrary position without using an optical system such as a lens. Further, since the angle of incidence and the angle of diffraction of light can be set arbitrarily, the design when mounting the information display source on the vehicle is facilitated. In addition, since the half width of the diffraction spectrum is narrow, a high-luminance display image can be obtained without deteriorating the foreground luminance, which is effective as a combiner for a display device.

FIG. 8 is a conceptual diagram showing an example of a HUD which is an example of a conventional holographic display system for an automobile. Light 3 containing information to be displayed, which is emitted from a light source 6 and passed through a transmission type liquid crystal display 5 through a lens system 4
Is irradiated on the hologram 2 provided on the windshield 7 of the vehicle body, diffracted, and visually recognized at the observation position 1 by the driver.
The lens system 4 has a function as a collimator. By giving the hologram 2 a magnification, the display images of the speed display 8 and the warning display 9 are formed as virtual images in the distance.

[0005] However, in such a conventional HUD, the hologram is arranged on the transparent portion of the windshield, so that light from the outside such as the sun or a street lamp is diffracted by the hologram and flare light is generated. When a non-specular reflection hologram is used, the flare light appears in a different direction from the actual external light source, and it appears that there are a plurality of external light sources. When a hologram having a magnification is used, the flare light moves differently from an actual external light source as the vehicle operates. Therefore, when flare light is generated, there is a problem that an observer feels troublesome and uncomfortable.
If the hologram is a regular reflection type without magnification, flare light will not be generated, but the advantage of using the hologram will be lost.

Therefore, it is conceivable to dispose the hologram in the dark shaded portion of the windshield. In this case, since the outside of the hologram is covered with the dark shade, light from outside the vehicle does not enter and the generation of flare light can be prevented. Although the dark shade exists around the entirety of the windshield, a certain area is required to provide the hologram, and it is natural to use the dark shade on the lower side of the windshield from the viewpoint of securing a view.
In addition, the lower side is preferable because an installation location of the information display source is required. When placing a hologram on the lower side of the windshield, to prevent the display image from being hidden by the handle,
It will be located near the center of the vehicle.

[0007] On the other hand, considering the requirements required for a display device arranged near the center of the vehicle, the display area is not a driver-specific display like a conventional HUD, but is a viewable area that can be seen by a passenger in a passenger seat or a rear seat. It needs to be wide. However, when a hologram having a magnification like a conventional HUD is used, a display image is formed at a long distance, but there is a problem that a viewing area becomes very narrow. Even if a passenger other than the driver forcibly peeked from the side, he could only see images with large blur and distortion due to aberrations.

In addition, if the hologram is given a large magnification because the dark shade on the lower side of the windshield is used, the display image is formed not in the front but in the direction of the hood, and it is as if the display image were formed. There was also a problem of giving a sense of incongruity as if it was stuck in the hood.

Therefore, a hologram in which the angle of incidence of light and the angle of diffraction are different, and the distance between the information display source and the hologram is substantially equal to the distance between the virtual image and the hologram, in other words, the magnification is approximately It is conceivable to use a hologram that is 1. By using such a hologram, it is possible to obtain a holographic display system for a vehicle having a wide viewing range that can be visually recognized by all persons in the vehicle.

[0010]

However, when such a non-specular hologram is used, the mountability of the information display source is improved, but the display image is inclined with respect to the line of sight as shown in FIG. When the observation position is changed, there is a problem that a display image is distorted. In order to solve this distortion, it is effective to tilt the surface of the display body of the information display source with respect to the optical axis as shown in FIG.

Although this method can correct the inclination of the display image, there is a problem that the vertical direction of the display image shrinks. For example, in the case of the figure, the vertical direction is 1/3 of the display body. Therefore, in order to obtain a display of a desired size, a display element which is three times larger than the originally required size is required. Also, it was practically difficult to mount a large display in a dashboard with no space. It is an object of the present invention to provide a new holographic display system for a vehicle, which solves the above-mentioned problems of the prior art.

[0012]

SUMMARY OF THE INVENTION The present invention provides an information display source having a light source and a display for displaying information to be displayed, and an information display source for generating information to be displayed as light, and a dark shade on a windshield of a vehicle. A holographic display system for a vehicle, comprising: a combiner having a hologram that is arranged in a part and diffracts the light toward an observer and displays it as a virtual image.
The hologram is a hologram having a diffraction characteristic in which the angle at which the light is incident on the hologram and the angle at which the light is diffracted by the hologram, and the display surface of the display body is such that the virtual image surface is substantially perpendicular to the line of sight. A hologram for a vehicle, wherein a prism made of a transparent material having two non-parallel surfaces is disposed between the hologram and the information display source. It is a display system.

[0013]

1 is a conceptual side view (a) and a front view (b) of a holographic display system for a vehicle according to the present invention. Hologram 2 is provided in a dark shade蔽部windshield 7 in their entirety are attached to the vehicle at an angle theta _w. An information display source is provided in the vehicle,
Light 3 containing information is irradiated from a display body 5 of an information display source to a combiner at an incident angle θ _i . The light is reflected and diffracted by the diffraction angle theta _d by the hologram, it is visible as the display image 10 to a viewer (e.g., driver) 1. Here is the display body 5
The feature of the present invention is that the prism 30 is arranged between the hologram 2 and the hologram 2. The hologram 2 is arranged at the center of the dark shade 11 on the lower side of the windshield 7, and a prism 30 is arranged between the display 5 and the hologram 2.

As a feature of the present invention, the incident angle θ _i and the diffraction angle θ
_d (θ _i ≠ θ _d ). The display body 5 is inclined with respect to the optical axis so that the display image 10 is substantially perpendicular to the line of sight. In the holographic display system for a vehicle having such a configuration, the display member 5 as in the present invention is used.
By disposing the prism 30 made of a transparent body having two non-parallel surfaces between the hologram 2 and the hologram 2, the display image 10 can obtain a display image substantially the same size as the display body without shrinking in the vertical direction. . Further, a display image without distortion can be visually recognized throughout the vehicle including the driver's seat, the passenger seat, and the rear seat.

The prism in the present invention is preferably made of a transparent body having two non-parallel surfaces. The material may be optical glass or quartz glass, or a resin material such as acrylic or polycarbonate. A resin material is preferable because it is lightweight and suitable for mass production.
Further, the term “transparent” means not only a completely colorless material but also a colored material as necessary. For example, in order to take measures against chromatic aberration and absorb unnecessary light such as infrared rays and ultraviolet rays, a function of blocking light in a specific wavelength range may be provided. As the prism shape, the incident angle θ _{i of the} hologram and the diffraction angle θ
_Although depending on the combination of _d , the apex angle is preferably about 20 to 60 °.

FIG. 2 is a conceptual side view showing another example of the holographic display system for a vehicle according to the present invention. In this example, a prism plate 31 having one surface divided at minute intervals is used instead of the above-described prism. 30
The same effect can be realized with a smaller size, lighter weight, and lower cost than using such a prism. The prism plate can be obtained by cutting the surface of glass, but a molded product of a resin material such as acrylic or polycarbonate is desirable because it is lightweight and suitable for mass production.

The shape of the surface is generally a sawtooth wave type having a vertex angle of 90 °, but may be changed according to the combination of the incident angle θ _i and the diffraction angle θ _d of the hologram. The distance (pitch) between the vertices is preferably about 0.1 to 2 mm, but a pitch of 1.0 mm or less is preferable because the influence on the resolution of the display image is small.

The display surface of the display according to the present invention is not perpendicular to the optical axis connecting the display and the hologram. Because the hologram is non-specular reflection as shown in FIG. 6, if the display body 5 is vertical (α = 90 °), the obtained display image 10 is inclined with respect to the line of sight. As a result, the display image is tilted and distorted with the movement of the observation position. To prevent this, the display image 10 becomes substantially perpendicular to the line of sight by tilting the display with respect to the optical axis (α ≠ 90 °) as shown in FIG. 7, and the image distortion can be corrected.

However, when the display is tilted as shown in FIG. 7, the vertical direction of the display image shrinks. Therefore, by using the prism 30 of FIG. 1A or the prism plate 31 of FIG. In addition, a display image without distortion can be obtained.

FIG. 3 is a schematic partial sectional view showing an example of the structure of the windshield according to the present invention. Two glasses 21,
The hologram 2 is sealed in a safety laminated glass in which the reference numeral 21 'is bonded by an intermediate film 22 such as polyvinyl butyral. More specifically, one surface of the hologram 2 is adhered to the vehicle interior glass plate 21 with an adhesive 23, and the other surface is a barrier film 24 for preventing a change in hologram characteristics by a plasticizer contained in the intermediate film 22. (In this example, a polyvinyl alcohol (PVA) film is used.)

A dark shade 11 is printed on the inside of the outside glass plate 21 '. Since the dark shade is opaque, the hologram 2 is not irradiated with light from the outside of the vehicle. Therefore, no flare light is generated. As the type of the glass plate used here, a transparent glass plate having no color or a glass plate colored with bronze or green can be used. In order to suppress light loss, it is desirable to use a non-colored glass plate for the vehicle interior glass.

The hologram constituting the combiner in the holographic display system for a vehicle of the present invention is, for example, a hologram having an area of usually several tens mm to several hundred mm square and a thickness of several μm to several tens μm. Is done. This hologram is of a reflection type, and a volume / phase hologram such as a Lippmann type is desirable in that high diffraction efficiency can be obtained.

The hologram of the present invention is a hologram and the incident angle theta _i and diffraction angle theta _d is different, are prepared as shown in FIG. It is obtained by irradiating two substantially parallel lights on the hologram photosensitive material at different incident angles and exposing them. That is, two light beams substantially parallel to the hologram photosensitive material 2 ′ may be irradiated from both sides so as to sandwich the photosensitive material at the incident angle θ _I and the incident angle θ _D (FIG. 4A). Substantially parallel light is obtained by converting light from a laser into divergent light by a spatial filter and collimating the light by a collimator lens or a concave mirror.

These lights need not necessarily be completely parallel, and may be divergent light from a distance sufficiently far from the size of the hologram (FIG. 4B). For example, it is preferable that the distances r _I and r _D from the divergence point to the photosensitive material be 1000 mm or more. In this case, it is desirable that r _I and r _D are approximately equal.

As the two lights, two substantially parallel lights may be actually used. However, one parallel light is applied to the hologram photosensitive material, the transmitted light is turned back by a mirror, and the predetermined light is again applied to the photosensitive material. A similar hologram can be obtained by irradiating at an angle.

In order to obtain a bright display image, it is preferable to expose the hologram in the present invention so that the diffraction wavelength at a predetermined observation position matches the wavelength of the light source.
For example, as shown in FIG. 5, in the case of a hologram in which light incident at an incident angle of 9 ° in front of the hologram (vehicle center) is diffracted at a diffraction angle of 65 °, the diffraction wavelength at the front is 55 °.
Assuming 5 nm, the viewpoint position corresponding to the driver's seat + 400 mm
The diffraction wavelength in the vicinity is around 545 nm (black circles in the graph). If a cathode ray tube having a peak near 545 nm is used as a light source, a bright display image can be obtained. If the wavelength at the front is 530 nm, it is 520 nm near the driver's seat.
(（In the graph). In this case, a fluorescent display tube (VFD) is suitable as a light source. Since the hologram is symmetrical, the above can be applied to the passenger seat.

The information display source according to the present invention has a function of emitting light to display an image. The information display source includes a so-called light receiving type display element such as a liquid crystal display element and a hot cathode tube (HC).
T), which emits light emitted from a light source such as a cold cathode tube or a halogen lamp. Alternatively, a light source itself may be patterned and arranged to generate specific information as light, such as a fluorescent display tube.

As these light sources, cathode tubes having a narrow spectral half width are preferable in that chromatic aberration due to the hologram is small. In the case of a light source having a wide half width, it is preferable to use an appropriate filter that limits the wavelength range.

The information to be displayed in the present invention is appropriately selected depending on the display application, and includes a speedometer, a tachometer, a shift lever display of a vehicle, various warning lights, navigation information, an air conditioner, and audio equipment. For example, information of an attached device can be exemplified. In addition, information from outside the vehicle such as road information and parking lot availability information can be displayed. The observer may include not only a driver such as a vehicle but also all passengers and other passengers.

[0030]

【Example】

(Example 1) In the holographic display system for a vehicle in FIG. 1, the windshield 7 is set so that θ _w = 35 ° with respect to the horizontal, and the incident angle θ _i from the center of the light source to the center of the hologram is 9 °. much trouble theta _d is 65 °. And TFT
The prism 30 was arranged between the display 5 composed of a type color liquid crystal element and the hologram 2. The distance from the hologram to the prism is 50 mm. The prism is made of acrylic resin and has a vertex angle of 38 °. The distance from the prism to the display was about 50 mm. The surface of the display was inclined by 15 ° with respect to the optical axis. The backlight of this display element is a cathode ray tube, and has a bright line spectrum having a peak near 545 nm.

In this example, the hologram is 20 μm thick.
Using a photosensitive material made of acrylic photopolymer,
A volume phase reflection hologram was used. The exposure of the hologram was performed with light of 565 nm of a dye laser. The laser light was spread by a spatial filter, and then collimated by a collimating lens. As shown in FIG. 3A, the photosensitive material was irradiated from both sides at θ _I = 9 ° and θ _D = 65 °. The hologram thus obtained reflects and diffracts light incident at 9 ° to 65 °. It has a diffraction peak near 555 nm, a diffraction efficiency of 95%, and a wavelength half width of about 2 nm.
It was 0 nm. Diffraction wavelength near driver and passenger seats is 5
It was around 45 nm.

The displayed image was visible from the whole of the vehicle including the driver's seat, the passenger seat, and the rear seat. In addition, a display image without any vertical shrinkage and distortion was obtained from anywhere in the vehicle. When the prism is not used, it is necessary to incline the surface of the display body by 33 ° with respect to the optical axis to correct the distortion of the display image, and the magnification in the vertical direction is about 0.38 times (shrink to about 1/3). ). On the other hand, when the prism was used according to the present invention as described above, the magnification in the vertical direction was 0.97 times, and a display image with almost no shrinkage was obtained. In addition, flare light was not generated because light from the outside was blocked by the dark shade area and did not enter the hologram.

(Example 2) In this example, the configuration shown in FIG. 2 was adopted. An acrylic resin product having a vertical angle of 90 ° and a pitch of 0.1 mm was used as the prism plate. Other configurations are the same as those in the first embodiment. In Example 2, a display image without shrinkage was obtained.

[0034]

According to the present invention, it is possible to realize a holographic display system for a vehicle which has no flare light, has a wide viewing range, and has no image vertical shrinkage and image distortion.

[Brief description of the drawings]

FIG. 1 is a side view (a) and a front view (b) showing an example of a holographic display system for a vehicle according to the present invention.

FIG. 2 is a side view showing another example of the holographic display system for a vehicle of the present invention.

FIG. 3 is a schematic partial sectional view showing an example of the structure of a windshield in the present invention.

FIG. 4A is a conceptual diagram showing an example of a method for producing a hologram according to the present invention, and FIG. 4B is a conceptual diagram showing another example.

FIG. 5 is a graph showing an example of a change in a diffraction wavelength when a viewpoint position of a hologram is changed in the present invention.

FIG. 6 is a conceptual diagram illustrating a tilt of a display body, a tilt and a distortion of a display image.

FIG. 7 is a conceptual diagram illustrating a tilt of a display body, a tilt and a distortion of a display image.

FIG. 8 is a conceptual diagram showing an example of a conventional holographic display system for a vehicle.

[Explanation of symbols]

 1: observer, 2: hologram, 2 ': hologram photosensitive material, 3: light containing information, 4: lens system, 5: display, 6: light source, 7: windshield, 8: speed display image, 9: Warning display image, 10: display image, 11: dark shade, 21, 21 ': glass plate, 22: interlayer, 23: adhesive, 24: barrier film, 30: prism, 31: prism plate.

Claims (3)

[Claims] An information display source having a light source and a display body for displaying information to be displayed, the information display source generating information to be displayed as light, and the light source disposed on a dark shaded portion of a windshield of a vehicle. A holographic display system for a vehicle comprising a combiner having a hologram that diffracts toward an observer and displays it as a virtual image, wherein the hologram has an angle at which the light is incident on the hologram and an angle at which the light is diffracted by the hologram. Is a hologram having different diffraction characteristics, the display surface of the display body is disposed inclined with respect to the optical axis so that the virtual image plane is substantially perpendicular to the line of sight, the hologram and the information display source A holographic display system for a vehicle, characterized in that a prism made of a transparent material having two non-parallel surfaces is disposed between them. 2. A holographic display system for a vehicle according to claim 1, wherein at least one surface of said prism is a prism plate divided at minute intervals. 3. The holographic display system for a vehicle according to claim 1, wherein the hologram is a hologram in which two substantially parallel lights are irradiated on a hologram photosensitive material at different incident angles to be exposed.