Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
1998-09-10
2001-02-06
Metjahic, Safet (Department: 2858)
Optics: image projectors
Composite projected image
Multicolor picture
C353S034000, C353S037000
Reexamination Certificate
active
06183093
ABSTRACT:
This application is based on patent application Nos. 9-248892 and 10-213208 filed in Japan, the contents of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
This invention relates to a light source device, an illuminator for a projector of a ray splitting type using a dichroic mirror for color separation, and an image projector provided with such an illuminator.
As optical image projectors, there have been marketed liquid crystal projectors. A liquid crystal projector acts as a means for displaying a large image. The projector enlargedly projects an optical image on a screen via a projection lens. The optical image emerges from liquid crystal panels after modulation of the luminance of illumination light in accordance with an image signal.
A schematic construction of an illumination optical system of such a liquid crystal projector is described with reference to FIG.
6
. In
FIG. 6
, white light is irradiated from lamps (light sources)
51
,
52
disposed in a vertical direction. Parallel light rays are directed onto a first lens array
53
. In this construction, parallel light rays of the lamp
51
are substantially incident onto an upper portion of the first lens array
53
while parallel light rays of the lamp
52
are substantially incident onto a lower portion of the first lens array
53
.
These parallel light rays are further bundled by the first lens array
53
and a second lens array
54
each including a plurality of lenses, and are incident onto a display screen of a liquid crystal panel
57
in a superposing manner via an integrating lens
55
and a field lens
56
. The first lens array
53
, the second lens array
54
, and the integrating lens
55
constitute an optical integrator.
Dichroic mirrors
58
,
59
constituting a color separating optical system are disposed between the optical integrator and the field lens
56
to separate the white light rays into color light rays in the wavelength range of Red (R), Green (G), and Blue (B). Generally, spectral characteristics of the dichroic mirror
58
(
59
) exhibit an incident angle dependency as shown in
FIGS. 7 and 8
. In other words, the wavelength range of transmitted light or reflected light differs depending on the incident angle of light. Hereafter, this characteristic is referred to as “incident angle characteristic”.
In the arrangement of the conventional liquid crystal projector, the two lamps
51
,
52
are disposed immediately before the optical integrator. As shown in
FIG. 6
, parallel light rays of the upper lamp
51
are incident onto substantially the upper portion of the first lens array
53
while parallel light rays of the lower lamp
52
are incident onto substantially the lower portion of the first lens array
53
. In this case, observing the light rays of the upper lamp
51
advancing to a center of the liquid crystal panel
57
or represented by the solid lines, these light rays are incident on the dichroic mirrors
58
,
59
at an angle of (45°+&agr;). On the other hand, observing the light rays of the lower lamp
52
advancing to the center of the liquid crystal panel
57
or represented by the broken lines, these light rays are incident on the dichroic mirrors
58
,
59
at an angle of (45°−&agr;).
As mentioned above, light rays of the upper lamp
51
are incident on the dichroic mirrors
58
,
59
at an angle different from those irradiated of the lower lamp
52
. Further, the dichroic mirrors
58
,
59
have the incident angle characteristics. Accordingly, the problem is likely to occur that the display screen of the liquid crystal panel
57
is illuminated at a different color tone. For this reason, in the case where one of the lamps used, such as, the case where the lamps
51
,
52
are alternately used, the case where one of the lamps
51
,
51
should keep turning on after the other lamp is turned off under a certain circumstance during the use of both lamps
51
,
52
, or in the case where the luminance of the lamps
51
,
52
differs from each other, the color tone of an optical image projected on the screen are likely to vary.
Also, it should be noted that unless the optical integrator is provided, it becomes more difficult to attain a luminance uniformity on the liquid crystal panel
57
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a light source device, an illuminator, and an image projector which have overcome the problems residing in the prior art.
According to an aspect of the present invention, a light source device comprises: a plurality of separate light sources which each irradiate light rays; and a light distributor which has a light incident surface and a light emerging surface, and receives light rays from each of the plurality of separate light sources on the light incident surface, and sends out light rays of each of the plurality of separate light sources parallel to a predetermined direction in a uniform distribution pattern from an entirety of the emerging surface.
According to another aspect of the present invention, an illuminator comprises: a plurality of separate light sources which each irradiate light rays; a light distributor which has a light incident surface and a light emerging surface, and receives light rays from each of the plurality of separate light sources on the light incident surface, and sends out light rays of each of the plurality of separate light sources parallel to a predetermined direction in a uniform distribution pattern from an entirety of the emerging surface; and an optical integrator which receives light rays from the light distributor, and send out enhanced light rays onto a target screen.
According to still another aspect of the present invention, an image projector comprises: a plurality of separate light sources which each irradiate light rays; a light distributor which has a light incident surface and a light emerging surface, and receives light rays from each of the plurality of separate light sources on the light incident surface, and sends out light rays of each of the plurality of separate light sources parallel to a predetermined direction in a uniform distribution pattern from an entirety of the emerging surface; an optical integrator which receives light rays from the light distributor, and send out enhanced light rays; a color separating optical system which separates light rays from the optical integrator into a plurality of color light rays based on the wavelength of light rays; a plurality of light valves which receive the plurality of color light rays from the color separating optical system, and respectively produces color optical images in accordance with an image signal; an image combiner which produces a combined optical image of color optical images produced by the plurality of light valves; and a projecting optical system which projects a combined optical image onto a screen.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings.
REFERENCES:
patent: 4726662 (1988-02-01), Cromack
patent: 4936659 (1990-06-01), Anderson et al.
patent: 5626409 (1997-05-01), Nakayama et al.
patent: 5743612 (1998-04-01), Matsuda et al.
patent: 5801795 (1998-09-01), Ogino
patent: 5805337 (1998-09-01), Yoshida
patent: 5815249 (1998-09-01), Nishi et al.
patent: 5917561 (1999-06-01), Hatanaka
patent: 6-265887 (1994-09-01), None
patent: 7-181392 (1995-07-01), None
Leroux E P
Metjahic Safet
Minolta Co. , Ltd.
Sidley & Austin
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