Computer graphics processing and selective visual display system – Plural physical display element control system – Optical means interposed in viewing path
Reexamination Certificate
1999-02-09
2003-07-08
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Optical means interposed in viewing path
C382S275000, C348S014010
Reexamination Certificate
active
06590548
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display apparatus and an image input apparatus used for the same, using a screen or a screen formed of a hologram. In particular, a first invention relates to a display apparatus which can suppress noise light coming into an observer's eyes so that it is possible to improve the contrast of an image displayed on the screen, and a second invention relates to an image input apparatus which can be effectively utilized in a TV conference system, a TV telephone system, etc., and can eliminate noise components contained in an input image.
2. Description of the Related Art
First, the related arts for the first invention will be explained in detail below.
As a display apparatus which focuses an image on a screen, there is a known projector-type display apparatus which utilizes a liquid crystal as a display unit. In the display apparatus of this type, first, the light is irradiated from a predetermined direction to either a transmitting type liquid crystal or a reflecting type liquid crystal. Next, the signal light including the image formed on the liquid crystal is emitted. Further, the image to be displayed (below, a display image) contained in the signal light is focused on the screen through a focus lens. Still further, either transmitted scattered-light or reflected scattered-light of the display image, which is emitted from the screen, is visually recognized by an observer.
As another type of the projector, a CRT (Cathode Ray Tube) type is used instead of a liquid crystal type. In the CRT type projector, the display image is focused on the screen by emitting three colored beams each formed of red (R), green (G) and blue (B).
In the display apparatus utilizing a normal screen mentioned above, there is a problem in which the contrast of the displayed image deteriorates due to the incoming light, from the surroundings, on the screen in a bright environment. Accordingly, the above display apparatus can be used only in a dark environment where the incoming light is poor and the brightness is limited.
In order to solve the above problem, a first solution lies in use of an optical element according to the present invention (i.e., a reflection preventing member, a polarized optical element, a light control optical member, etc.) which is explained in detail in the description of the present invention.
Further, a second solution lies in use of a hologram as the screen (below, a hologram screen). According to the hologram screen, the characteristic of the screen can function as a scattering body for only particular light input from a particular direction due to a diffraction effect of the hologram.
That is, when the hologram which recorded the scattered light is utilized as the screen, the light is scattered for only the irradiated light (i.e., signal light) input from the particular direction, and other light input from other directions are transmitted or reflected (i.e., a regular reflection) on the screen.
As a result, almost all light input from the surroundings is not scattered on the screen. Accordingly, it is possible to solve a problem in which the brightness at the background of the screen is increased, and the contrast of the displayed image can be improved. This conventional art has been disclosed, for example, in the Japanese Unexamined Patent Publication (Kokai) No. 5-333435.
Further, in addition to the above structure using the hologram screen, there is a method in which an external light absorbing member (for example, black paint, etc.) which absorbs the external light is provided inside of the hologram screen in order to absorb the external light. This art has been disclosed, for example, in the Japanese Unexamined Patent Publication (Kokai) No. 5-88020.
In this art, however, there is another problem as explained below. That is, when the strong external light, such as sunlight or the light of a lamp, which is input from the direction opposite to the signal light, is input on the hologram screen, the diffracted light is reflected on the rear side of the hologram screen, and the reflected light is directed to the observer. As a result, the contrast of the image becomes worse and the observer is very hard to observe the displayed image.
As a solution for the above problem, the following method has been proposed. That is, a reflection preventing member is provided to the rear side of the screen, and a polarized optical element is provided on the observer's side of the hologram screen.
In the display apparatus using the hologram screen, as explained above, when strong external light, such as sunlight or the light of the lamp, is input to the hologram screen, it is possible to reduce noise light caused by the scattering or diffraction on the hologram screen.
There are problems, however, in the above explained conventional arts as briefly explained below. That is, in the conventional hologram screen, regardless of the diffraction, there is the difference in refractive index on the boundary surface between the external air and the structural member of the hologram screen in the observer's side and in the rear side, and, as a result, reflection occurs in the boundary surface. As a result, the background at the observer's side overlaps with the image displayed on the hologram screen so that there is a problem in which it is difficult to see the image due to deterioration of the contrast of the image.
Further, since the hologram screen has a light-transmitting characteristic, and since the observer can see the rear side of the image (i.e., a rear side of the hologram screen), when there is internal light, such as the light from a room lamp, on the rear side of the image, the internal light is overlapped with the image so that the contrast of the image is deteriorated and the observer is difficult to see the displayed image. The above two problems are explained in detail with reference to
FIGS. 11 and 12
below.
Next, the related arts for the second invention will be explained in detail below.
For example, when taking a picture of a speaker through a camera in a TV conference system, a TV telephone system, a prompter system, etc., the viewline of the speaker is usually directed to a display unit of the system, and is not directed to the camera (i.e., an image input unit). Accordingly, in actual use of the TV conference system or the TV telephone system, there is a problem in which a feeling of disorder occurs between speakers since the viewline of one speaker does not meet that of another speaker through the camera.
As one solution of this problem, there is a known art disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 6-30406. According to this document, in order for the viewlines between speakers to meet, the signal light in which the information to be displayed is recorded therein is irradiated to a screen which has the function of transmitting or scattering the light in accordance with the incident angle of the light, the speaker's image is displayed on the screen, and the image of the speaker (i.e., the observer who watches the display unit) is captured by the image input unit (i.e., a camera) through the screen.
As another solution, there is another known art disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 9-168141. According to this document, the signal light in which the information to be displayed is recorded therein is irradiated to the hologram screen (i.e., as mentioned above, the hologram is used as the screen), another speaker is displayed on the hologram screen, and the image of the speaker (i.e., the observer who watches the display unit) is captured by the image input unit (i.e., a camera) through the hologram screen. There are, however, subjects to be solved in these conventional arts as explained in detail with reference to
FIGS. 29
to
31
below.
SUMMARY OF THE INVENTION
The object of the first invention is to provide a display apparatus which can suppress the first noise light caused by the back
Matsumoto Tooru
Mizutani Yasuhiro
Takada Kenichiro
Denso Corporation
Eisen Alexander
Harness Dickey & Pierce PLC
Hjerpe Richard
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