JPH03225386A - Holographic display device - Google Patents

Abstract

PURPOSE:To arbitrarily select the position of a light source and to completely display an image without disturbing the field of vision from the light source by irradiating a sensitive material with one light beams through a diffusion plate and the other light beams without through the diffusion plate and forming an interference fringe. CONSTITUTION:Laser beams emitting from a laser oscillator 1 are bisected by a beam splitter 4. A hologram original plate 1 is irradiated with one light beams as a spherical wave via a reflection mirror 5, a convex lens 6, and the diffusion plate 2 such as ground glass, and the other light beams as a plane wave via the reflection mirror 7, and convex lenses 8 and 9, and a translucent hologram sheet 10 is produced. The hologram sheet 10 is attached to the laminated surface side of a laminated glass 11 where two plate glasses are stuck with a intermediate film such as polyvinyl butyral, during reproducing. When the light beams from a white light source 12 is projected on the hologram sheet 10 as parallel light via a mask plate 14 by a convex lens 13, display information is surely recognized 16 from the wide range of the opposite side of the light source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a holographic ink display device that can be used as various displays such as high-mount stop lamps for automobiles and shop window displays.

[Prior Art] Conventionally, high-mounted stop lamps with an integrated light source and housing have been installed directly on or in contact with the rear window glass of a vehicle, which not only narrows the free space but also reduces the visibility of the driver, etc. It was inevitable that this would become a hindrance.

In order to solve this problem, the light from the light source can be displayed by projecting it onto the transmission hologram sheet. In addition, when a point light source such as a light bulb is used as a light source for exposure and reproduction, the reproduced diffraction image becomes a virtual image of the light bulb, bright in the center and dark in the surroundings, making the displayed image only partially visible. First, there is a drawback that the entire display image cannot be completely displayed. Furthermore, in order to display a display image completely, if exposure and reproduction are performed using parallel light, the direction of diffraction is fixed, resulting in a disadvantage that the display image cannot be viewed in various directions.

In addition, when displaying information such as letters or patterns by interposing a patterned mask plate obtained by forming an opaque part on transparent glass or the like between a plain transparent hologram sheet and a reproduction light source, When a point light source is used as a light source for exposure and reproduction, there are the same drawbacks as when displaying as mere light as described above. Further, even when parallel light is used, there are the same drawbacks as when using parallel light as described above.

Furthermore, when displaying a pattern using a display such as a fluorescent display tube and a plain transmission hologram sheet, the light emitted from one point on the display satisfies the Bragg condition on the hologram sheet. Since there are a plurality of layouts that satisfy this condition, the light emitted from the - point appears as a plurality of points on the hologram, resulting in a blurred display image, which has the disadvantage that it cannot be displayed completely.

[Object of the invention] The present invention solves these various drawbacks,
An object of the present invention is to provide a holographic display device in which the position of a light source can be arbitrarily selected, a display image can be completely displayed without obstructing the view from the light source side, and the display image can be viewed 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 transmitting the information through a transmission type hologram sheet, in which the hologram sheet transmits one light through a diffusion plate. The other light is characterized by being irradiated onto the sensitive material without passing through the diffusion plate to form interference fringes.

[Function] As shown in the schematic diagram of the main part during exposure in FIG.
A transmission type hologram sheet is used in which one of the two light beams split from a laser light source 1 is irradiated onto a sensitive material without passing through a diffuser plate 2 such as frosted glass, and interference fringes are formed by irradiating the other light onto a sensitive material without passing through the diffuser plate. It is to be displayed.

When one of the lights is projected onto the diffuser plate during exposure, it is scattered and behaves as if there were many point light sources and spherical waves were generated from these point light sources. As a result, during playback, the second
As shown in the figure, when display information is projected from a point light source 12 onto a transmission hologram sheet via a mask plate 14, it is diffracted over a wide range by the transmission hologram sheet, so the display information can be projected from a wide range on the opposite side of the light source. Can be clearly seen.

In other words, even if the light irradiating the transmission hologram sheet is parallel light (plane wave) as well as light from a point light source (spherical wave), the diffracted light is scattered around the point of incidence on the transmission hologram sheet. Since it becomes light, this point of incidence can be seen as a single point from anywhere on the diffracted light side. Therefore, all the points of incidence of the incident light are seen as a set of independent points, so they are not blurred.

Utilizing this effect, if a transmission hologram sheet is irradiated with light from a point light source or parallel light, only that part will emit light, making it possible to display a clear pattern.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 and 3 are diagrams showing the optical system during the production of the transmission type hologram sheet of the present invention, and Figures 2 and 4 are diagrams showing an example of application as a high-mount stop lamp to the rear window glass of an automobile. FIG.

An example in which the light irradiated onto the transmission hologram sheet during reproduction is a parallel wave will be explained based on FIGS. 1 and 2.

(Preparation of transmission hologram sheet) A hologram original plate 3, which is made by coating a polyester film with, for example, dichromate gelatin as a sensitive material and drying it, is
Exposure is performed using an optical system as shown in the figure.

The laser beam emitted from the argon laser transmitter 1 is split into two by a beam splitter 4, one of which is converted into a spherical wave via a reflecting mirror 5, a convex lens 6, and a diffuser plate 2 such as ground glass, and the other is converted into a spherical wave by a reflecting mirror 7 and a convex lens 8. The hologram original plate 1 is irradiated as a plane wave through a convex lens 9, and then developed by a usual method to produce a transmission hologram sheet 10.

In addition, the wavelength of the laser light (laser oscillator) and the incident angle of the laser light from two directions with respect to the hologram original plate l are:
It may be set using Bragg's equation, taking into consideration conditions during reproduction (positioning of the light source and human eyes, type of light source), changes in the thickness of the photosensitive material, etc.

(Reproduction of holographic display device) The transmission hologram sheet 10 thus obtained is combined with a laminated glass 11, which is made by bonding two plate glasses with an interlayer film such as polyvinyl butyral, as shown in FIG.
It is installed as a high-mounted stop lamp on the mating surface side of the vehicle, and is installed as a rear window glass for automobiles.

In addition, a light source 12 for reproduction such as a white light source is connected to a convex lens 13,
A reproduction light source 12 is provided on the upper surface of the rear bar cell 15 together with a mask plate 14 such as one composed of a red filter and a liquid crystal plate so as to be at the focal point of the convex lens 13.

With such an optical system, the light from the white light source 12 is made into parallel light by the convex lens 13, and is transmitted through the mask plate 14 into 5 parallel lights.
When display information such as TOP is projected onto the transmission hologram sheet 10, it is diffracted by the transmission hologram sheet as scattered light around the incident point, reaches the human eye 16, and, for example, the driver of a following car receives 5T0P. The text is clearly visible.

In this case, the driver and passenger of a car equipped with the display device will not recognize the characters 5TOP and will not interfere with external visibility.

[1] The fabrication of the transmission hologram sheet, which will be explained based on FIGS. 3 and 4 using an example in which the light irradiated onto the transmission hologram sheet 10 during reproduction is a spherical wave, is performed using the beam splitter 4.
It was produced by the same method as in Example 1 except that the other laser beam divided into two was made into a spherical wave through a convex lens 8.
Reproduction is performed in the same manner as in Example 1, except that the convex lens 13 is omitted and the beam is incident on the transmission hologram sheet 10 as a spherical wave, as shown in FIG.

In this case as well, the same effects as in Example 1 were obtained.

Although the present invention has been described above using preferred embodiments, the present invention is not limited to these embodiments, and can be applied to various applications.

As the diffuser plate, a light-transmissive diffuser plate, such as frosted glass, having minute irregularities formed on its surface can be used.

A mask plate can be one in which the pattern to be displayed is formed by a part that transmits light and a part that does not transmit light; for example, it can be cut out of a material that does not transmit light, or it can be made by forming an opaque part on a transparent plate such as glass. However, it is preferable to use a liquid crystal filter because the displayed information can be changed freely.In addition to the pattern, the entire transmission hologram sheet can also be displayed in the same color. In this case, a mask plate is not required.

In addition to dichromate gelatin, the photosensitive material may be appropriately selected and used, such as silver halide photosensitive materials, various photopolymers, and photoresists.

In addition, since hologram sheets generally deteriorate when they absorb moisture, it is preferable to sandwich them between two interlayer films in laminated glass, but they may also be sandwiched between an interlayer film and a plate glass, and the surface If it is coated with a protective film, it can also be provided on a single glass plate.

Regarding the light source during reproduction, various point light sources such as a laser light source can be used in addition to a white light source.

In addition to the high-mounted stop lamp, the display device of the present invention may be used for decorative display in various colors, and therefore can be applied not only to vehicle windows but also to architectural windows, partitions, etc.

[Effect of the Invention 1] The holographic display device of the present invention allows various display information to be completely viewed from the opposite side of the light source over the entire transmission hologram sheet from a wide angle without obstructing the 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 windows of buildings, vehicles, etc. with narrow indoor spaces.

[Brief explanation of drawings]

Figures 1 and 3 are diagrams showing the optical system during the production of the transmission type hologram sheet of the present invention, and Figures 2 and 4 are diagrams showing an example of application as a high-mount stop lamp to the rear window glass of an automobile. FIG. 1...Laser oscillator 2...Diffusion plate 3...Hologram original plate 10...Transmission type hologram sheet 11...Laminated glass 12...Light source 14...Mask plate 16...Eye

Claims (1)

[Claims] In a holographic display device that displays display information by transmitting display information through a transmission type hologram sheet, the hologram sheet transmits one light through a diffusion plate and the other light onto a sensitive material without passing through the diffusion plate. A holographic display device characterized by forming interference fringes through irradiation.