Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Reexamination Certificate
2002-01-03
2004-08-03
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
C359S599000
Reexamination Certificate
active
06771404
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hologram screen for producing full-color or monochromatic still image or moving image by projecting image-forming light.
2. Related Art
There has heretofore been known a hologram screen for producing advertisements such as of moving image or still image by sticking it onto a show window or the like, and projecting image-forming light
3
from a projector
2
as shown in
FIGS. 15A and 15B
.
The hologram screens can roughly be divided into a transmission-type hologram screen
9
which permits the image-forming light
3
to pass through as shown in
FIG. 15A and a
refection-type hologram screen
90
which reflects the image-forming light
3
as shown in FIG.
15
B.
That is, the transmission-type hologram screen
9
shown in
FIG. 15A
comprises a transparent member
91
and a transmission-type hologram film
92
stuck to the transparent member
91
, and the reflection-type hologram screen
90
shown in
FIG. 15B
comprises a transparent member
91
and a reflection-type hologram film
920
stuck to the transparent member
91
.
The transmission-type hologram screen
9
and the reflection-type hologram screen
90
are used depending upon their respective applications. Namely, the transmission-type hologram screen
9
is used in an application where a viewer E
2
views the image from the side opposite to the projector
2
as shown in FIG.
15
A. This can be represented by, for example, the one where advertisements are to be displayed in front of the shop.
On the other hand, the reflection-type hologram screen
90
is used in an application where a viewer E
1
views the image from the side of the projector
2
as shown in FIG.
15
B. This can be represented by, for example, one where advertisements are to be displayed inside the shop.
Demands, in the market, are increasing for both of these hologram screens.
However, production of the above-mentioned hologram films
92
and
920
requires precise and large-scale optical systems for exposure to light as well as a highly sophisticated technology. Besides, the transmission-type hologram film
92
and the reflection-type hologram film
920
are produced requiring different kinds of optical systems for exposure to light and different kinds of production technology. Therefore, it is difficult to produce both the transmission-type hologram film
92
and the reflection-type hologram film
920
, and a tremendously large cost of investment and cost of development are needed if both of them are to be produced.
It has therefore been desired to produce not only the transmission-type hologram screen but also the reflection-type hologram screen by using the transmission-type hologram film
92
.
SUMMARY OF THE INVENTION
The present invention was accomplished in view of the problems inherent in the above prior art, and its object is to produce a hologram screen that can be easily produced by using the transmission-type hologram film enabling the image to be seen from the side of the projector.
The present invention is concerned with a hologram screen having a transparent member and a hologram film stuck to the transparent member and producing image by projecting image-forming light from a projector, wherein:
the hologram film is a transmission-type hologram film; and
a reflector for reflecting the image-forming light is arranged on the back surface side of the hologram film.
In the present invention, what draws the greatest attention is that the hologram film is the transmission-type hologram film, and that a reflector for reflecting the image-forming light is arranged on the back surface side of the transmission-type hologram film.
The reflector may be the one which totally reflects the image-forming light or may be the one which permits part of the image-forming light to pass through.
In connection with the hologram film and the like in this specification, the side on where the projector is arranged is referred to as “front surface side” and the opposite side is referred to as “back surface side”.
Further, the projector is, for example, a liquid crystal projector, and the image may be, for example, a full-color or monochromatic still image or moving image.
The hologram film may be directly stuck to the transparent member, or may be stuck to the transparent member via any other member such as the above-mentioned reflector or the like. The reflector may be directly stuck to the back surface of the hologram film (see embodiment 1) or may be stuck to the back surface of the transparent member (see embodiment 2).
Next, the operation and advantage of the invention will be described.
The above-mentioned hologram film is a transmission type hologram film. Therefore, when an image light is projected from an upper diagonal direction onto the hologram film, for example, the image light is diffracted and scattered on the hologram film to pass therethrough in a substantially horizontal direction.
Since the reflector is arranged on the back surface side of the hologram film, the image-forming light passing through the hologram film is reflected in a substantially horizontal direction.
Therefore, the image light travels to the front surface side of the hologram screen. Thus, a viewer at the front surface side of the hologram screen can see the image.
As such, since the hologram screen is constructed of the transparent-type hologram film stuck to the transparent member, the image can be recognized from the side of the projector. Therefore, even though the transparent-type hologram film is employed, the hologram screen functions as a reflection-type hologram screen.
On the other hand, the hologram screen can be used as a transparent-type hologram screen by which an image can be recognized at the side opposite to the projector. That is, by using a hologram film for manufacturing a transparent-type hologram screen, the hologram film having a reflecting function can be easily manufactured.
Therefore, there is no need of making an investment or developing the technology for particularly producing the reflection-type hologram screen, and the hologram screen can be cheaply produced.
Besides, the background light from the side opposite to the viewer passes through the hologram screen to some extent provided the reflector is not the one which totally reflects light. Therefore, the viewer is allowed to see, as a background, the opposite side of the hologram screen.
According to the present invention as described above, the hologram screen can be easily produced by using the transmission-type hologram film, the hologram screen enabling the image to be seen from the side of the projector.
According to the second aspect of the present invention, the hologram film may be so arranged as to produce an image on the front surface side of the hologram screen by permitting the image-forming light directly projected from the projector to pass through without causing it to be diffracted, and by diffracting the image-forming light that is reflected by the reflector after having passed through the hologram film (embodiment 4, FIG.
9
).
In this case, the image can be produced on the front surface side only of the hologram screen so will not to be viewed from the back surface side.
According to the third aspect of the present invention, it is desired that the reflector is arranged between the hologram film and the transparent member.
Thereby, the reproduced images are not overlapped one upon the other by the reflection by the front surface and the back surface of the transparent member, and a favorable image is obtained.
According to the fourth aspect of the present invention, the reflector is one obtained by directly coating the transparent member with a metal or a nonmetal, one obtained by sticking a metal-coated resin film onto the transparent member, or one obtained by sticking a metal foil onto the transparent member.
Thus, it is allowed to obtain a reflector which efficiently reflects the image-forming light and to easily produce the hologram screen.
As the above metal, there can be used, for
Mizutani Yasuhiro
Suzuki Kazunori
Amari Alessandro
Robinson Mark A.
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