Optics: image projectors – Polarizer or interference filter
Reexamination Certificate
1999-12-17
2002-01-08
Dowling, William (Department: 2851)
Optics: image projectors
Polarizer or interference filter
C353S094000
Reexamination Certificate
active
06336724
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a projector device and particularly to a projector device using a DMD (Mirror Reflection Type Light Modulator).
The projector device using the conventional DMD will be described hereinafter with reference to the drawings.
FIG. 1
is a diagram for typically describing a structure of the conventional projector device. As shown in
FIG. 1
, a light beam emitted from a light source
101
is reflected by an ellipsoidal mirror
102
and condensed into a rod integrator
106
and, thereafter, irradiated at a DMD
108
through a relay lens
104
, a reflecting mirror
105
, a reflecting prism
106
and a color prism
107
. The light beam reflected by the DMD
108
is magnified by the color prism
107
and the reflecting prism
106
and then projected onto a screen
110
.
In case of the conventional system as described above, it is necessary to increase an output of the light source
101
to obtain a high luminance. If the output of the light source
101
is increased, however, consumption power is also increased with a result that a larger power source for lamp is required.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a projector device which is capable of obtaining a high luminance without increasing the output of the light source.
Other objects of the present invention will become clear as the description proceeds.
To achieve the above described object in the projector device for magnifically projecting onto a screen a beam of light emitted from a light source which is irradiated at a mirror reflection type light modulator after being color-separated into light beams of three primary colors and after respective light beams of primary colors modulated in the mirror reflection type light modulator are synthesized by said color prism, the present invention has, in a first viewpoint, two light source systems. A light beam of one light source is polarized into a light beam composed of a single polarization component by a polarization converter constructed by a polarization plate and a phase difference plate opposed to each other. A light beam of another light source is polarized into a light beam which is 90° different in a polarization direction from the light beam of said one light source, thereby light beams of said two light sources are synthesized by a polarization beam splitter.
In a second viewpoint, in the projector device for magnifically projecting onto a screen a beam of light emitted from a light source which is irradiated at a mirror reflection type light converter after being color-separated into light beams of three primary colors by a color prism and after respective light beams of primary colors modulated in the mirror reflection type light converter are synthesized, the present invention at least comprises: two light sources; a polarization converter for polarizing light beams of respective light sources; and a polarization beam splitter for synthesizing polarized light beams of respective light sources. A light beam emitted from a first light source transmits through said polarization beam splitter after being polarized into a “p” polarization by said polarization converter. A light beam emitted from a second light source is reflected by said polarization beam splitter after being polarized into a “s” polarization by said polarization converter, thereby light beams emitted by the two light sources are synthesized.
Further, in a third viewpoint, in the projector device for magnifically projecting onto a screen a beam of light emitted from a light source which is irradiated at a mirror reflection type light modulator after being color-separated into light beams of three primary colors and after respective light beams of primary colors modulated in the mirror reflection type light modulator are synthesized, the present invention at least comprises: two light sources; two luminance regulators for equalizing the luminance of light flux of respective light sources; two polarization converters for polarizing light beams of respective light sources; and a polarization beam splitter for synthesizing polarized light beams of respective light sources. A light beam emitted from a first light source becomes an uniform light flux in a first luminance regulator and transmits through said polarization beam splitter after being polarized into a “p” polarization by a first polarization converter. A light beam of a second light source becomes an uniform light flux in a second luminance regulator and is reflected by said polarization beam splitter after being polarized into a “s” polarization by a second polarization converter, thereby light beams emitted from the two light sources are synthesized.
Furthermore, in a fourth viewpoint, in the projector device for magnifically projecting onto a screen a beam of light emitted from a light source which is irradiated at a mirror reflection type light converter after being color-separated into light beams of three primary colors and after respective light beams of primary colors modulated in the mirror reflection type light modulator are synthesized, the present invention at least comprises: two light sources; two lens portions for making light beams of respective light sources into collimated light beams; two luminance regulators for equalizing the luminance of light flux of respective light sources; and a polarization beam splitter for synthesizing polarized light beams of respective light sources. A light beam emitted from a first light source and changed into a collimated light beam in a first lens portion becomes an uniform light flux in a first luminance regulator and transmits through said polarization beam splitter and is output from a second light source after being polarized into a “p” polarization by a first polarization converter. A light beam emitted from a second light source and changed into a collimated light beam becomes an uniform light beam in a second luminance regulator and is reflected by said polarization beam splitter after being polarized into a “s” polarization by a second polarization converter, thereby light beams emitted from the two light sources are synthesized.
It is preferable for the present invention that said polarization converter is constructed by a polarization plate and a phase difference plate opposed to each other and that said luminance regulator comprises fly's eye lenses constructed by a number of lens elements.
Since, by the above structure, the present invention polarizes the light beams emitted from the two light sources into a “p” polarization and a “s” polarization respectively by a polarization converter and thereafter, synthesize them by a polarization beam splitter, the light beams emitted from the two light sources can be projected onto a screen without attenuation.
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Matsumoto Takayuki
Shouji Eisaku
Takeuchi Katsuyuki
Dowling William
Michael Best & Friedrich LLC
NEC Corporation
Whitesel J. Warren
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