JP3473152B2 - Hologram screen manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a holographic screen which allows the back side of the screen to be seen through.

[0002]

2. Description of the Related Art Holographic screens utilizing the diffraction characteristics of holograms are known (Japanese Patent Laid-Open No. 5-880).
No. 20, Japanese Patent Publication No. 5-85910, etc.). Japanese Patent Publication No. 5-85910 discloses a display device in which a scattering plate (diffusion plate) is recorded on a hologram and a display image formed on a hologram screen is visually recognized from a wide range, and a method for manufacturing the hologram. There is.

Further, in Japanese Patent Laid-Open No. 5-88020,
A method for limiting the angle range in which the display can be viewed by utilizing the directivity of the hologram and a method for suppressing the influence of external light by utilizing the light transmitting property of the hologram and the light absorbing member are shown. In addition, as another application of the hologram screen, a translucent display device having a function of seeing through a scene or a person (background) behind the screen and a function of forming a display image on the screen from the front side is known. Has been.

Such a see-through display device includes a head-up display of an automobile and a display device of a window for responding to a customer through a semi-transparent display screen. An optical screen is used for a screen using a hologram. The diffuser is recorded. The manufacturing method of this hologram screen is
The laser light is divided into two light beams, one light beam is emitted as reference light from one side of the photosensitive plate, the other light beam is transmitted through the diffusion plate, and the transmitted diffused light is emitted as object light from the other side of the photosensitive plate. A method of forming an interference fringe on a photosensitive plate is known (see Japanese Patent Publication No. 5-85910).

[0005]

However, the method of manufacturing a hologram screen by the two-beam method has the following problems. That is, the regular object light (transmitted diffused light) transmitted through the diffuser plate and the reflected diffused light reflected by the reference light transmitted through the photosensitive plate hitting the diffuser plate interfere with each other and are recorded in the hologram as noise.

When the noise light (reflected diffused light) is not present, the background light incident from the back side of the hologram screen during reproduction passes through the hologram screen well, but when the noise light is recorded, the background light is recorded. The transmittance of the is significantly reduced (see FIG. 3B described later). And
This decrease in transmittance becomes greater as the diffuser plate is incomplete and has directivity (incomplete diffuser plate). As a result, the background seen through the holographic screen appears cloudy and unclear. The present invention has been made in view of the above problems, and an object of the present invention is to provide an excellent method for manufacturing a hologram screen that does not make it difficult to see the scene on the back side of the screen.

[0007]

According to the present invention, a diffuser plate is used for visually recognizing a scene on the back side of a screen by light transmitted from the back side and visually recognizing a display image by superimposing it on the background by light reflected from the front side. Is a method of manufacturing a reflection type hologram screen in which a diffuser plate is disposed on the back side of the photosensitive plate, reference light is irradiated from the front side of the photosensitive plate, and the diffused plate is transmitted through the photosensitive plate. When the diffusely reflected light is used as the object light and interference fringes are formed by the object light and the reference light , the diffuser plate is a flat plate without bending.
It has a shape, and the tilt angle with respect to the photosensitive plate is changed.
A method for manufacturing a hologram screen is characterized in that interference fringes are recorded in multiple layers (claim 1).

[0008]

[0009]

[0010]

[0011]

[0012]

In order to obtain a full-color hologram, when the reference light is made to have three wavelength bands corresponding to the three primary colors and interference fringes are recorded in a multiplexed manner, methylene blue is added to the photosensitive agent used for the photosensitive plate. It is preferable to use sensitized dichromated gelatin (MBDCG). M above
This is because BDCG has high sensitivity in the entire visible light range and can record three colors of blue, green and red in one layer.

[0014]

In the method of manufacturing the hologram screen according to the present invention, the reference light incident from one side of the photosensitive plate,
An interference fringe is formed by the reference light and the diffuse reflection light that is transmitted through the photosensitive plate and reflected by the diffusion plate. That is, the object light is diffused light formed by the light incident from the single direction by the reference light. Then, the reference light does not enter the diffuser plate from the other direction, so that the diffused light that becomes noise is not mixed. Therefore, even if the diffuser plate is an incomplete diffuser plate, the directivity of the diffuser plate recorded in the hologram is a single direction, and the direction corresponds to the incident direction of the reproduction light.

That is, the reference light transmitted through the photosensitive plate forms only regular object light and does not form noise light as in the case of the conventional two-beam method. As a result, in the hologram screen manufactured by this manufacturing method, the background light is transmitted without being scattered, and as a result, the transmittance becomes good and the background can be visually recognized well (see Example 1). In addition, the inclination angle of the diffusion plate with respect to the photosensitive plate is increased.
Change in stages and perform multiple exposure (multiple recording of interference fringes)
Because the display image is seen on the hologram screen
The range of the visible area becomes wider and the direction in which the visible area expands
Can be adjusted according to the direction of the tilt angle.
There are points (see Example 3). As described above, according to the present invention, it is possible to provide a hologram manufacturing method capable of manufacturing an excellent hologram screen in which the scene on the back side of the screen is not difficult to see.

[0016]

【Example】

Example 1 As shown in FIG. 2, the hologram screen 61 manufactured according to this example has a light (background light 7) transmitted from the back side.
1) visually recognizes the scene on the back side of the screen 61 and visually recognizes the display image on the background by the light reflected from the front side (reflected diffused light 73 of the display light 72). It has a reflection type hologram element 611 in which 1) is recorded.

In this embodiment, as shown in FIG. 1, a diffusion plate 21 is arranged on the back side of the photosensitive plate 10, the reference light 31 is irradiated from the front side of the photosensitive plate 10, and the light is transmitted through the photosensitive plate 10. The light diffusely reflected by the diffuser 21 is designated as the object light 33, and the object light 33
This is a method of manufacturing the hologram screen 61 in which interference fringes are formed by the reference light 31 and the reference light 31. The diffusion plate 21 has a flat plate shape without bending and is arranged in parallel with the photosensitive plate 10. The photosensitive material of the photosensitive plate 10 is dichromate gelatin (MBDCG) sensitized with methylene blue.
Consists of. Then, the wavelength of the reference light 31 is set to three primary colors (RB
Interference fringes are recorded in multiple by three wavelengths corresponding to the wavelength of G).

The photosensitive plate 10 is a dry plate 11 coated with a photosensitive material.
Is sandwiched between the glass substrates 12 and 13 with antireflection coating via an index matching liquid. The light source for exposure has three laser light sources 411 to 413 corresponding to the three primary colors. Then, the laser beams 301 to 303 emitted from each of them are bundled by the half mirrors 421 to 423, and are reflected by the mirrors 431 and 4
After passing through 32, it is diverged by the convex lens 44 to become the reference light 31.

The position of the convex lens 44 with respect to the photosensitive plate 10 is substantially the same as the position of the projection device 65 with respect to the hologram screen 61 during reproduction shown in FIG. The transmitted reference light 32 that has passed through the photosensitive plate 10 is diffused and reflected by the diffusion plate 21 to become the object light 33, and forms an interference fringe with the reference light 31. After that, the photosensitive plate 10 becomes the hologram screen 61 by performing a normal developing process.

Then, as shown in FIG.
When a display image is formed on the display image 1, the reflected diffused light 73 relating to the display image is scattered forward from the hologram screen 61. Then, the display image can be visually recognized from the visual field range substantially equal to the directivity of the diffusion plate 21. Further, the background light 71 passes through the hologram screen 61, so that the viewer 81 can visually recognize the scene behind the screen (the outsider 82, etc.). The object light 33 recorded on the diffuser plate 21 does not include noise light having different directivities, so that the transmittance of the background light 71 does not decrease and is extremely good.

FIG. 3 shows this concretely with experimental data. That is, the transmittance of the hologram screen manufactured by the conventional method (two-beam method) is as shown in FIG.
Although the wavelength characteristic as shown in (b) is shown, the hologram screen 61 manufactured by the method of this example has the same characteristics as shown in (a) of FIG.
Shows wavelength characteristics such as. From this figure, it can be immediately seen that the average level of transmittance has increased from about 50% to about 80%.

In the figure, the low transmittance region (recessed portion 8
5, 86) is due to the diffraction of the hologram element 611. As can be seen from FIG. 3, the hologram screen 61 according to this example allows the background to be recognized very clearly. As described above, according to this example, it is possible to manufacture an excellent hologram screen in which the scene on the back side of the screen is not difficult to see.

Example 2 In this example, as shown in FIG.
1 is a method for manufacturing a hologram screen 61 in which 1 is arranged non-parallel to the photosensitive plate 10. The diffusion plate 21 is arranged non-parallel to the photosensitive plate 10 with a certain inclination angle θ. As a result, as shown in FIG. 5A, the projection device 6 that occurs when the diffuser plate 21 is an incomplete diffuser plate during reproduction.
The light source virtual image 79 of No. 5 comes to deviate from the center of the viewing area 85 (angle α), and reduces glare generated for the viewer 81.

That is, as shown in FIG.
When manufactured in parallel with 0, the virtual light source image 79 is located near the center of the viewing area 85 as shown in FIG.
In the case of this example, as shown in FIG. Others are the same as those in the first embodiment.

Example 3 In this example, as shown in FIG.
The inclination angle θ between 1 and the photosensitive plate 10 has three levels (θ = 0, β ₁ ,
This is a manufacturing method of the hologram screen 61 in which multiple exposure is carried out by changing to β ₁ + β ₂ ). That is, the diffusion plate 21 is exposed in the parallel (θ = 0) to the photosensitive plate 10, rotates clockwise _{(θ = β 1, β 1} + β 2) is allowed to expose twice. In addition,
The order of exposure may be counterclockwise, and the order is not particularly limited.

As a result, the angle range (directivity angle) of the reflected and diffused light 331 to 333 of the hologram screen 61 at the time of reproduction is widened, and the viewing area of the hologram screen 61 can be expanded. The figure shows the case where the vertical viewing area is widened, but it is naturally possible to widen the horizontal viewing area depending on the inclination direction of the diffusion plate.

Further, since the diffusion plate 21 is rotated in a fixed direction with respect to the photosensitive plate 10, the virtual light source image 79 deviates in a fixed direction from the center of the visual field due to the same effect as described in the second embodiment, and the glare is reduced. It has the effect of lowering it. Others are the same as those in the first embodiment.

Example 4 In this example, as shown in FIG.
2 is a curved surface with a constant curvature, and the center of the curvature is the reference light 3
It is another embodiment in which it is located on the opposite side of the first light source. As a result, the directivity angle of the diffused light of the diffusion plate 22 becomes wider, and the viewing area of the hologram screen 61 becomes wider.
On the other hand, if the curvature of the diffuser plate is reversed (convex → concave),
The displayed image can be brightened instead of narrowing the viewing zone. Others are the same as those in the first embodiment.

[Brief description of drawings]

FIG. 1 is an optical system configuration diagram of a manufacturing method according to a first embodiment.

FIG. 2 is a configuration diagram of an optical system during reproduction of the hologram screen according to the first embodiment.

FIG. 3 is a characteristic diagram showing the transmittance (a) of background light of a hologram screen manufactured by the manufacturing method of Example 1 and the transmittance (b) of a hologram screen by a conventional method.

FIG. 4 is an optical system configuration diagram of a manufacturing method according to a second embodiment.

5A is a diagram showing a position of a light source virtual image when reproducing a hologram screen manufactured by a manufacturing method of Example 2 and FIG. 5B is a diagram showing a position of a light source virtual image of a hologram screen by a conventional method.

FIG. 6 is an optical system configuration diagram of a manufacturing method of a third embodiment.

FIG. 7 is an optical system configuration diagram of a manufacturing method of Example 4.

[Explanation of symbols]

10. ． ． Photosensitive plate, 21. ． ． Diffuser, 31. ． ． Reference light, 33. ． ． Object light,

Front Page Continuation (72) Inventor Katsuhide Akimoto 1-1, Showa-cho, Kariya, Aichi Japan Denso Co., Ltd. (72) Inventor Toru Matsumoto 1-1-chome, Showa-cho, Kariya, Aichi Nihon Denso Co., Ltd. (56 ) References: Fukukaihei 6-2369 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03H 1/04

Claims (2)

(57) [Claims] 1. A reflection type recording a diffusion plate used for visually recognizing a scene on the back side of a screen by light transmitted from the back side and visually recognizing a display image superimposed on the background by light reflected from the front side. In the method for manufacturing a hologram screen as described above, a diffusion plate is arranged on the back side of the photosensitive plate, reference light is irradiated from the front side of the photosensitive plate, and light transmitted through the photosensitive plate and diffusely reflected by the diffusion plate is and object light hits the forming interference fringes by the the object light and the reference light, the diffusion plate has a free plate shape of bending, the
Multiple recording of interference fringes by changing the tilt angle with respect to the photosensitive plate
A method for manufacturing a holographic screen characterized by
Law. 2. The photosensitive material of the photosensitive plate according to claim 1, wherein the photosensitive material is made of dichromated gelatin sensitized with methylene blue, and the reference light has three wavelength bands corresponding to three primary colors. A method for manufacturing a full-color hologram screen, characterized in that interference fringes are recorded in multiple layers.