JPH10254336A - Holographic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holographic display device without blur by chromatic aberration even by using fluorescent display tube by providing a fluorescent display tube to an information display source and using specific phosphor for this fluorescent display tube. SOLUTION: Light 3 containing information from an information display source provided with a fluorescent display tube 21 is diffracted by a combiner 20 comprised of a substrate with a hologram formed thereon and visually recognized by an observer 1 as a virtual display image 10. Here, as phosphor of the fluorescent display tube 21, ZnGa2 O4 :Mn is used. Contrasted with a 100nm or longer half-value width of an emission spectrum of a phosphor ZnO:Zn which is generally used, ZnGa2 04 :Mn phosphor has an about 25nm of a half-value width of the emission spectrum, therefore, generation of chromatic aberration is reduced to a quarter or less than that of conventional one, and a sufficiently permissible display image is obtained. As a display pattern, phosphor may be patterned and arranged in a segment form, but a dot matrix type is more desirable because it can display a higher degree of information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a holographic display device.

[0002]

2. Description of the Related Art With the recent development of hologram materials and laser technology, products using holograms are increasing.
For example, a hologram is used as an optical element in a holographic display device that diffracts light containing information and displays the information to an observer. In addition, forgery prevention marks on ID cards and credit cards, decorative holograms, hologram calendars, and the like use holograms on which images are recorded.

The following are specific examples. 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 recently been used. This means that the optical information projected from the information projection means such as a liquid crystal display device,
The image is projected on a combiner including a hologram and a half mirror incorporated in a windshield of an automobile or the like, so that the driver can read information from the driving state without moving the viewpoint.

In particular, a hologram as a combiner not only can freely set an incident angle and a diffraction angle to diffract optical information toward a driver, but also has a lens function and the like. It is possible to diffract optical information in the direction of the driver's field of view or to form an image at an arbitrary position without using an optical system such as a lens. 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. 4 is a conceptual diagram showing an example of a conventional HUD. Light 3 including information to be displayed, which is emitted from a light source 6 and passes through a transmission type liquid crystal display element 5 via a lens system 4 and a wavelength selection filter 11, is applied to a hologram 2 provided on a windshield 7 of a vehicle body. The light is diffracted and is visually recognized at the observation position 1 by the driver. The lens system 4 has a function as a collimator. At this time, the windshield 7 is a laminated glass, and the hologram 2 is sealed in the laminated glass. The hologram 2 has a wavelength selection function, and a desired multicolor image can be displayed by using a hologram subjected to multiple exposure. For example,
By setting the speed display 8 to green and the warning display 9 to red, information can be more accurately transmitted to the driver.

[0006]

However, since holograms utilize diffraction, there is a problem of blurring of an image due to occurrence of chromatic aberration. Therefore, conventionally, a cathode tube having a narrow wavelength half width (about 6 nm) has been used as a light source of a transmission type liquid crystal display element,
It was necessary to use an interference filter having a narrow wavelength half width as in the above example. When a cathode ray tube is used as a light source, an inverter circuit is required, which is not only expensive, but also difficult to adjust the brightness (dimming). In interference filters,
A filter having a narrow half width and a high transmittance requires a multilayer coating, and is very expensive.

When a light source with a narrow half width is used, it is necessary to match the peak wavelength of the light source with the diffraction wavelength of the hologram, which also requires a precise hologram fabrication technique. When the reproduction wavelength fluctuates due to manufacturing variations of the hologram and the interference filter, there is also a problem that the brightness of the display image is reduced. Furthermore, even if ideal wavelength matching is enabled, there is a problem of temperature characteristics. When the diffraction wavelength of the hologram fluctuates due to a change in the temperature of the environment, there is a problem that the brightness of the displayed image is also lowered.

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

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises an information display source for generating information to be displayed as light, a base material, and a base material. A holographic display device having at least a combiner having a hologram for diffracting the light toward an observer and displaying the hologram as a virtual image, wherein the information display source is provided with a fluorescent display tube, A holographic display device characterized in that the phosphor is ZnGa ₂ O ₄ : Mn.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the holographic display device of the present invention.

Light 3 containing information from an information display source 21 having a fluorescent display tube is diffracted by a combiner 20 in which a hologram is arranged on a base material, and is displayed to a viewer 1 as a virtual image 10 displayed.
It is visually recognized as. The present invention is characterized in that ZnGa ₂ O ₄ : Mn is used as a phosphor of the fluorescent display tube 21.

FIG. 2 shows ZnGa ₂ O ₄ used in the present invention:
2 shows emission spectra of a Mn phosphor and a fluorescent display tube of a zinc oxide (ZnO: Zn) phosphor generally used conventionally. The conventional ZnO: Zn phosphor has a half width of the emission spectrum of 100 nm or more. On the other hand, the ZnGa ₂ O ₄ : Mn phosphor used in the present invention has a half width of the emission spectrum of about 25 nm (peak wavelength is about 505 nm). Therefore, in the holographic display device of the present invention, the occurrence of chromatic aberration is less than or equal to one-fourth of the related art, and a sufficiently acceptable display image can be obtained.

As described above, according to the present invention, a holographic display device can be realized by a relatively inexpensive fluorescent display tube without using an expensive liquid crystal display element and a cathode tube or an interference filter as in the prior art. Also, since a light source with a wider half-value width can be used compared to a cathode ray tube, even if the diffraction wavelength of the hologram slightly fluctuates due to manufacturing variations and temperature characteristics,
No significant decrease in brightness occurs.

The fluorescent display tube of the present invention is made of ZnGa ₂
O ₄ : Mn is used as a phosphor. As the display pattern, the phosphors may be patterned and arranged in segments, but a dot matrix type arrangement is preferable in that more advanced information can be displayed.

The combiner according to the present invention comprises a hologram arranged on a base material. As the hologram, a hologram having an area of about several tens mm to several hundreds of mm square and a thickness of about several μm to several tens μm is exemplified.

This hologram is preferable in that a volume / phase hologram such as a Lippmann type can obtain a high diffraction efficiency, but a hologram such as an emboss type or a rainbow type can be widely used. The type of the hologram is not particularly limited, such as a transmission type and a reflection type. As hologram materials, photopolymers such as acrylic and polyvinyl carbazole,
Various photosensitive materials such as dichromated gelatin, photo resist, and silver salt can be used.

The substrate in the present invention is appropriately selected according to the use and the state of use. It goes without saying that the incident side of the reproduction light and the exit side of the diffracted light with respect to the hologram are transparent substrates, but this may be one that partially transmits light. For example, a non-colored transparent glass plate or a glass plate colored with bronze or green can be used as the base material. Further, a portion through which the reproduction light or the diffracted light does not pass may be opaque.

The material of the substrate may be glass, a resin substrate of acrylic, polycarbonate, polyvinyl chloride, polyolefin, or the like, or a transparent crystal. The thickness of the substrate may be a plate having a thickness of several mm, a film having a thickness of 1 mm or less, or a block having a thickness of several cm. The surface of these substrates may be provided with an antireflection coating or a hard coating, if necessary.

Further, an optical member such as a lens and a mirror, a light polarizing means, or a non-linear optical element may be arranged in the optical path before the light is projected on the hologram.

The holographic display device of the present invention is suitably used in an automobile HUD as in the conventional example shown in FIG. Further, a so-called separately mounted HUD (see FIG. 3) is more preferable, in which a combiner is pivotally supported by a main body provided with an information display source, is mounted on a dashboard of a vehicle, and allows a driver or the like to visually recognize driving information. Can be used.
The information display source and combiner are integrated, and the fluorescent display tube has both functions in comparison with the conventional information display source, which is composed of a combination of a light source and a transmissive liquid crystal display element and is large. Therefore, a small and lightweight holographic display device can be realized. This separate type H
In the UD, the use of a resin material as the base material of the combiner is preferable in that it is lighter in weight than glass and that the combiner is hard to be damaged even if a collision occurs.

FIG. 3 shows an example of the separate type HUD. The combiner 20 is rotatably supported by the main body 22 of the HUD via a holding member 24. Angle to the horizontal of the combiner during use is theta _w. An adjustable leg 23 is provided on the bottom surface of the main body 22 as needed, and the leg 23 is held at a location where the HUD is installed (for example, on a dashboard of a vehicle). In the main body 22,
An information display source 21 having a circuit section 25 and a fluorescent display tube using ZnGa ₂ O ₄ : Mn as a fluorescent substance is provided, and irradiates a light 3 containing information toward the combiner at an incident angle θ _i . The light is reflected and diffracted by the diffraction angle theta _d by the hologram, it becomes an observer (e.g., a driver) 1 to be visually recognized as a display image 10 of the operation information.

When the holographic display device of the present invention is used for a vehicle, the information to be displayed is appropriately selected according to the display purpose, and may be a speedometer, a tachometer, a shift lever display of a vehicle, and various other information. Warning lamps, navigation information, information on ancillary equipment such as air conditioners and audio equipment, and the like.
Further, it is of course possible to display information from outside the vehicle such as road information and parking lot availability information. For aircraft and ships, various information related to vehicle operation and duties, such as position and orientation information such as latitude, longitude, altitude, direction of travel, weather information, radar obstacle information, fish finder information, etc. can be considered. . The observer is mainly a driver of a vehicle such as a vehicle, but may include a passenger seat and other passengers, and all of these persons.

The holographic display device of the present invention can be used for various purposes other than the example applied to the HUD for automobiles. For example, the present invention can also be used for a holographic display device in which a hologram is arranged in a dark-colored ceramic painted portion around a windshield of an automobile. In this case, because the dark ceramic painted part absorbs solar heat and the temperature fluctuates drastically,
The configuration of the present invention is particularly effective. Further, the present invention can be widely applied to all display devices using holograms, such as a virtual image corner marker for indicating a corner of a vehicle.

[0024]

An embodiment in which the display device of the present invention shown in FIG. 3 is applied to a separately mounted HUD will be described below. Combiner 20
Is manufactured by integrally molding an acrylic resin with a hologram. The combiner 20 is rotatably supported by the main body 22 of the HUD via a holding member 24. In use, the angle of the combiner to the horizontal is θ _w = 75
゜.

The fluorescent display tube 21 has a driver circuit built in on a semiconductor chip, and a ZnGa ₂ O ₄ : Mn phosphor is formed in a dot matrix. The number of dots is 128 × 32 and the size is 44 × 11 mm. The light emitted from the fluorescent display tube 21 is applied to the combiner 20 by θ _i =
It is incident at 20 ° and diffracted at θ _d = 20 °. Fluorescent display tube 2
The distance r _i from 1 to the combiner 20 is 80 mm, and the distance r _d from the combiner 20 to the display image 10 is about 200 mm. The diffraction wavelength of the hologram is about 505n
m, and a bright display image was obtained by matching with the emission wavelength of the fluorescent display tube.

The hologram is obtained by exposing light having a wavelength of about 505 nm incident at an incident angle of 20 ° so as to be reflected and diffracted at a diffraction angle of 20 °. In this case, light from two exposure light sources that emit light having a wavelength of about 505 nm may be incident on the hologram photosensitive material at an incident angle of 20 °, or light from an exposure light source that emits light having a wavelength other than 505 nm. May be incident on the hologram photosensitive material at an incident angle other than 20 °, and a hologram having the above-mentioned diffraction characteristics may be produced by various methods at the time of hologram exposure. In this embodiment, the incident angle and the diffraction angle are equal,
Although a hologram having a magnification of 2.5 times was used, the present invention is not limited to this incidence / emission angle and magnification.

As described above, by using the fluorescent display tube as the information display source, a small, light and thin holographic display device free from blur due to chromatic aberration can be realized.

[0028]

According to the present invention, a holographic display device free from blur due to chromatic aberration can be obtained even when a fluorescent display tube is used. Further, a holographic display device in which a significant decrease in luminance does not occur even if the reproduction wavelength of the hologram fluctuates due to manufacturing variations or temperature fluctuations.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a holographic display device of the present invention.

FIG. 2 is a spectrum diagram of a fluorescent display tube used in the holographic display device of the present invention.

FIG. 3 is a schematic sectional view showing a specific example of the holographic display device of the present invention.

FIG. 4 is a conceptual diagram showing an example of a conventional HUD.

[Explanation of symbols]

 1: observer 3: light containing information 10: display image 20: combiner 21: fluorescent display tube 22: main body 23: legs 24: holding unit 25: circuit unit

Claims (2)

[Claims] An information display source for generating information to be displayed as light, a combiner having a base material and a hologram arranged on the base material and diffracting the light toward an observer to display the light as a virtual image. A holographic display device having at least a fluorescent display tube as the information display source, and the fluorescent material of the fluorescent display tube is ZnGa ₂ O ₄ : M.
a holographic display device characterized by n. 2. The information display source according to claim 1, wherein the information display source is housed in a main body of the display device, and the combiner is rotatably supported by the main body near a lower side thereof. Holographic display device.