JP2891499B2 - Holographic display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a holographic display device that can be applied as various display bodies such as a high-mount stop lamp for a car and a display of a show window.

[Prior Art] Conventionally, a high-mount stop lamp in which a light source and a housing are integrated is provided directly or in contact with a rear window glass of a vehicle, so that not only the free space is narrowed, but also the visibility of a driver or the like. It was inevitable that this would be a hindrance.

In order to solve such a problem, light from a light source may be projected onto a transmission hologram sheet and displayed.
At this time, when a plain transmissive hologram sheet is used to display as mere light, and when a point light source such as a light bulb is used as a light source for exposure and reproduction, the reproduced diffraction image is There is a disadvantage that the image becomes a virtual image, the center is bright and the surroundings are dark, the display image is only partially visible, and the entire display image cannot be completely displayed. Further, when exposure and reproduction are performed with parallel light in order to completely display the display image, the diffraction direction is determined, and there is a disadvantage that the display image cannot be visually recognized in various directions.

Further, between a plain transmission hologram sheet and a light source for reproduction, a patterned mask plate obtained by forming an opaque portion on transparent glass or the like is interposed to display information such as characters and patterns. When a point light source is used as a light source for exposure and reproduction, there is the same drawback as in the case of displaying as simple light as described above. Further, even with the parallel light, there is the same drawback as in the case of using the above-mentioned parallel light.

Further, when a pattern is displayed using a display such as a fluorescent display tube for displaying the pattern and a plain transmission hologram sheet, light emitted from one point of the display is subjected to a Bragg condition on the hologram sheet. Since there are a plurality of layouts that satisfy the condition, the light emitted from the one point is seen at a plurality of points on the hologram, resulting in a blurred display image, which cannot be completely displayed.

[Object of the Invention] The present invention is to solve such various drawbacks, and it is possible to arbitrarily select the position of the light source and to completely display the display image without obstructing the field of view from the light source side. It is another object of the present invention to provide a holographic display device that can be visually recognized from various angles.

[Means for Solving the Problems] The display device of the present invention is a holographic display device that displays display information by irradiating the transmission type hologram sheet with the display information to transmit the display information. Is a diffuser separated from the photosensitive material,
The other light is applied to the light-sensitive material without passing through the diffusion plate to form an interference fringe to form a hologram in which information to be displayed is not recorded, and information to be displayed is provided between the hologram sheet and the light source for reproduction. A mask plate formed by a portion that transmits light and a portion that does not transmit light.

[Operation] As shown in the schematic view of the main part at the time of exposure in FIG. 1, one of the two light beams split from a laser light source 1 passes through a diffusion plate 2 such as frosted glass, and the other light beam is The display is performed using a transmission hologram sheet in which interference fringes are formed by irradiating the photosensitive material without passing through the diffusion plate.

When one light is projected onto the diffusion plate during exposure, there are as many point light sources as scattered, and these point light sources act so as to generate spherical waves. As a result, at the time of reproduction, as shown in FIG. 2, when display information is projected from the point light source 12 to the transmission hologram sheet via the mask plate 14, the light is diffracted over a wide range by the transmission hologram sheet. The display information can be clearly recognized from a wide range on the side.

That is, even if the light applied to the transmission hologram sheet is not only light (spherical wave) from a point light source but also parallel light (plane wave), the diffracted light is scattered around the point of incidence on the transmission hologram sheet. Since the light becomes light, this incident point can be visually recognized as one point from anywhere on the diffracted light side. Therefore,
Since all the incident points of the incident light appear as a set of independent points, there is no blur.

When light or parallel light from a point light source is applied to the transmission hologram sheet using such an action, only that portion emits light and a clear pattern can be displayed.

Examples Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 3 are views showing an optical system for producing a transmission type hologram sheet of the present invention, and FIGS. 2 and 4 are views each showing an example of application as a high mount stop lamp to a rear window glass of an automobile. FIG.

Example 1 An example in which irradiation light to a transmission type hologram sheet during reproduction is a parallel wave will be described with reference to FIGS.

(Preparation of Transmission Hologram Sheet) A hologram master 3 coated and dried on a polyester film, for example, using dichromated gelatin as a photosensitive material, is exposed by an optical system as shown in FIG.

A laser beam transmitted from an argon laser transmitter 1 is split into two by a beam splitter 4, one of which is a reflecting mirror 5,
The hologram original plate 1 is irradiated as a spherical wave through the convex lens 6 and the diffusion plate 2 such as frosted glass, and the other is irradiated as a plane wave through the reflecting mirror 7, the convex lens 8 and the convex lens 9 and then developed by a normal method to be a transmission type. The hologram sheet 10 is manufactured.

The wavelength of the laser beam (laser oscillator) and the angles of incidence of the laser beam from the two directions on the hologram master 1 are determined during reproduction (the arrangement of the light source and the human eye, the type of light source)
What is necessary is just to set by Bragg's formula in consideration of the change in thickness of the photosensitive material and the like.

(Reproduction of holographic display device) Transmission hologram sheet 10 thus obtained
As shown in FIG. 2, a laminated glass 11 in which two glass sheets are bonded by an intermediate film such as polyvinyl butyral.
It is provided as a high-mount stop lamp on the mating side of, and is mounted as a rear window glass for automobiles.

In addition, the reproduction light source 12 such as a white light source and the mask plate 14 such as one composed of a red filter and a liquid crystal plate are used together with the convex lens 13 so that the reproduction light source 12 is located at the focal position of the convex lens 13 on the upper surface of the rear parcel 15. To be provided.

With such an optical system, when the light from the white light source 12 is converted into parallel light by the convex lens 13 and display information such as STOP is projected onto the transmission hologram sheet 10 through the mask plate 14, the transmission hologram sheet The light is diffracted as scattered light around the point of incidence, and reaches the human eyes 16, for example, the driver of a following vehicle can clearly see the word STOP.

In this case, the character "STOP" is not recognized by a driver or a passenger of the vehicle equipped with the display device, and does not hinder external visibility.

Example 2 An example in which irradiation light to the transmission type hologram sheet 10 at the time of reproduction is a spherical wave will be described with reference to FIGS. 3 and 4. The production of a transmission type hologram sheet is divided into two by the beam splitter 4. The laser beam was produced in the same manner as in Example 1 except that the laser beam was converted into a spherical wave via the convex lens 8. Reproduction was performed by removing the convex lens 13 and entering the transmission type hologram sheet 10 as a spherical wave as shown in FIG. The reproduction is performed in the same manner as in the first embodiment except that the reproduction is performed.

 In this case, the same effect as that of the first embodiment was obtained.

Although the preferred embodiments have been described above, the present invention is not limited to these embodiments, and various applications are possible.

As the diffusion plate, a light-transmitting diffusion plate having fine irregularities formed on its surface, such as frosted glass, can be used.

If the mask plate is formed of a pattern to be displayed by a light transmitting part and a light non-transmitting part, for example, a cutout of a material that does not transmit light, or a transparent plate such as glass formed with an opaque part However, it is preferable to use a liquid crystal filter because display information can be freely changed.

As for the photosensitive material, a silver halide photosensitive material, various photopolymers, a photoresist and the like may be appropriately selected and used in addition to the dichromated gelatin.

Also, the hologram sheet generally deteriorates when it absorbs moisture, so it is preferable that the hologram sheet is sandwiched between two interlayer films in a laminated glass, but it may be sandwiched between the interlayer film and the plate glass. If a protective film is coated on the single-pane glass, it can be provided.

As a light source at the time of reproduction, various point light sources such as a laser light source can be employed in addition to a white light source.

Further, the display device of the present invention may be decoratively displayed in various colors, in addition to the high-mount stop lamp,
Therefore, the present invention can be applied not only to vehicle windows, but also to building windows, partitions, and the like.

[Effect of the Invention] The holographic display device of the present invention allows various types of display information to be completely and entirely visible from the opposite side of the light source over the entire transmission hologram sheet without obstructing the field of view from the light source side. Since the position of the light source can be freely selected depending on the conditions at the time of exposure, it is particularly suitable for displaying through a window of a building or a vehicle having a narrow indoor space.

[Brief description of the drawings]

FIGS. 1 and 3 are views showing an optical system for producing a transmission type hologram sheet of the present invention, and FIGS. 2 and 4 are views each showing an example of application as a high mount stop lamp to a rear window glass of an automobile. FIG. DESCRIPTION OF SYMBOLS 1 ... Laser oscillator 2 ... Diffusion plate 3 ... Hologram base plate 10 ... Transmission hologram sheet 11 ... Laminated glass 12 ... Light source 14 ... Mask plate 16 ... Eyes

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-173782 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03H 1/22 G02B 5/32

Claims (1)

(57) [Claims] 1. A holographic display device for displaying display information by irradiating the hologram sheet with display information and transmitting the display information, wherein the hologram sheet has one light transmitted through a diffusion plate separated from a photosensitive material. The other light is applied to the light-sensitive material without passing through the diffusion plate to form an interference fringe, thereby forming a hologram in which information to be displayed is not recorded, and displaying the hologram between the hologram sheet and the reproduction light source. A holographic display device comprising a mask plate formed by a portion that transmits information and a portion that does not transmit information.