Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
2001-03-05
2002-11-19
Adams, Russell (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S033000, C353S020000, C353S034000, C353S037000, C353S081000, C353S099000, C349S005000, C349S008000, C349S009000
Reexamination Certificate
active
06481852
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a projector apparatus, and more particularly to a projector apparatus which separates white light into light components of the primary colors, modulates the separated light components, and then composes the modulated light components.
BACKGROUND OF THE INVENTION
There are various conventional projector apparatuses for projecting images according to image signals. These projector apparatuses are classified into a system wherein white light from a light source is passed through a full-color light modulator followed by projection, and a system wherein white light from a light source is separated into light components or the three primary colors which are passed through respective light modulators and then composed, followed by projection. The invention belongs to the latter system.
Japanese Patent Laid-Open No. 171045/1998 discloses a projector apparatus which separates light using two dichroic mirrors and composes the separated light components using a cross-dichroic prism. Technique described in this publication will be explained as a first example of prior art.
FIG. 3
is a side view illustrating the structure of the first example of the conventional projector apparatus.
The projector apparatus shown in
FIG. 3
comprises a light source optical system
600
, a light separating optical system
700
, a light guide optical system
720
, a light composing optical system
780
, an projection lens
770
.
Light having random polarization components emitted from a light source
611
is reflected from a concave mirror
612
and then enters first and second integrators
620
,
630
.
The first and second integrators
620
,
630
each comprise a number of minute rectangular lenses, which have been continuously arranged in a planar matrix form, and function to homogenize the illuminance distribution of the incident light and then to output the homogenized light.
The polarization light converter
640
arranges the light, output from the first and second integrator, in a specific linear polarization direction and outputs the arranged light. This light from the light source
611
is then passed through a focusing lens
650
and a reflecting mirror
660
and is applied to irradiation areas near light valves
750
,
752
and a light guide lens
730
.
A first dichroic mirror
710
reflects red light and green light components among the components of the incident light, and permits only a blue light component to be passed therethrough. The transmitted blue light component is passed through a reflecting mirror
718
, a condenser lens
744
, and a light valve
750
in that order, and then enters a cross-dichroic prism
760
.
The second dichroic mirror
712
permits the transmission of only the red light component out of the red light and green light components as the incident light, and reflects only the green light component. The reflected green light component is passed through the condenser lens
742
and the light valve
752
in that order, and then enters the cross-dichroic prism
760
.
On the other hand, the red light component passed through the second dichroic mirror
720
is passed through a light guide lens
730
, a reflecting mirror
722
, a light guide lens
734
a reflecting mirror
724
, a condenser lens
744
, and a light valve
754
in that order, and then enters the cross-dichroic prism
760
.
The red light, green light, and blue light components input into the cross-dichroic prism
760
are composed to form a full-color image which is then projected in an enlarged manner onto a projection screen
800
through a projection lens
770
.
Thus, the projector apparatus as the first example of the prior art has a structure such that light components of the three primary colors are introduced into the second cross-dichroic prism
760
from three sides around the second cross dichroic prism
760
to compose the introduced light components.
Japanese Patent Laid-Open No. 158167/1993 discloses a projector apparatus which separates light using a cross-dichroic mirror and composes the separated light components using another cross-dichroic mirror. The technique described in this publication will be explained as a second example of prior art.
FIG. 4
is a perspective view illustrating the structure of the second example of the conventional projector apparatus.
The projector apparatus shown in
FIG. 4
comprises a light source
911
, a concave mirror
933
, a first cross-dichroic mirror
931
, reflecting mirrors
934
,
935
,
937
,
938
,
940
,
941
, liquid crystal panels
936
,
939
,
942
, a second cross-dichroic mirror
932
, and a projection lens
943
.
Light having random polarization components emitted from the light source
911
is reflected from the concave mirror
933
and then enters the first cross-dichroic mirror
931
.
The first cross-dichroic mirror
931
comprises a combination of a red transmission cross-dichroic mirror and a blue transmission cross-dichroic mirror which each are disposed on the optical axis
911
x
of the light source
911
so as to be inclined at 45 degrees to the optical axis
911
x
and to be orthogonal to each other and functions to separate white light from the light source
911
into light components of the three primary colors, red light, green light, and blue light components.
A pair of reflecting mirrors
934
and
935
, a pair of reflecting mirrors
937
and
938
, and a pair of reflecting mirrors
940
and
941
are disposed respectively on the optical paths of green light, red light, and blue light components to bend each of the optical paths to form a “⊃” shape.
The second cross-dichroic mirror
932
comprises a combination of a red reflection dichroic mirror and a blue reflection dichroic mirror which each are disposed so as to be inclined at 45 degrees to the output optical axis and to be disposed orthogonal to each other. The second cross-dichroic mirror
932
is disposed just under and adjacent to the first cross-dichroic mirror
931
, and composes the green light, red light, and blue light components reflected by the reflecting mirrors
935
,
938
,
941
to form a full-color light which is then output.
The full-color light composed by the second cross-dichroic mirror
932
is projected as a projection image by the projection lens
943
onto the projection screen
944
.
Thus, in the projector apparatus according to the second example of the prior art, the adoption of a structure, wherein the first and second cross-dichroic mirrors
931
,
932
are put on top of the other respectively as upper and lower cross-dichroic mirrors so as to be adjacent to each other, has eliminated the need to provide the light guide optical system
720
in the projector apparatus according to the first example of the prior art.
The projector apparatuses according to the above examples of the prior art, however, had the following problems.
In the projector apparatus according to the first example or the prior art, the light components of the three primary colors should be introduced from the three sides around the second cross-dichroic prism
760
. Therefore, the provision of the light guide optical system
720
is indispensable for the structure.
Since, however, the optical path length of the red light component passed through the light guide optical system
720
is different from the optical path lengths of the green light and blue light components not passed through the light guide optical system
720
, the illuminance distribution on a light valve
733
on the optical path of the red light component is unfavorably different from the illuminance distributions on light valves
731
,
732
on the light paths of the green light and blue light components. Consequently, when white is displayed on the whole projection screen, a problem of color shading occurs, that is, there is a difference in color between the center portion of the projected image on the projection screen
800
and the periphery of the projected image.
Likewise, since the quantity of the red light component incident to the projection lens
770
is
Adams Russell
Koval Melissa
NEC Corporation
Whitham Curtis & Christofferson, PC
LandOfFree
Projector apparatus comprising a light composing optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Projector apparatus comprising a light composing optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Projector apparatus comprising a light composing optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2977209