Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2000-02-17
2002-02-05
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C362S268000
Reexamination Certificate
active
06344929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an illumination apparatus and a projection type display apparatus and, more particularly, to a projector which projects an image (light) supplied from a liquid crystal display element or from a display element of any other type. The invention is suitably applicable to liquid crystal projectors and the like.
2. Related Background Art
A variety of proposals have been made heretofore as to the technology for the liquid crystal projectors constructed to illuminate a liquid crystal panel (liquid crystal display element) with light from a light source and enlarge and project an image based on transmitted light or reflected light modulated by and emerging from the liquid crystal panel, through a projection lens onto a screen.
A TN (Twist Nematic) liquid crystal panel, which is often used in the liquid crystal projectors, is normally provided with polarizing filters such as polarizers, analyzers, or the like before and after a liquid crystal layer.
The polarizing filters have such characteristics as to transmit only a specific polarization component out of incident light but intercept a polarization component whose polarization direction is perpendicular thereto. For this reason, in the liquid crystal projectors, at least half of the light from the light source was intercepted at the polarizing filter on the light incident side of the liquid crystal panel and thus brightness of the image projected on the screen tended to become lowered.
As an illumination apparatus for the liquid crystal projectors, for example, Japanese Patent Application Laid-Open No. 9-311297 suggests the illumination apparatus that uniformly illuminates an area to be illuminated while increasing the utilization efficiency of light from the light source, using polarization converting elements for converting the incident light of non-polarized light into beams of linearly polarized light polarized in a specific direction and two lens arrays (optical integrators) placed in series for uniformly illuminating the area on the surface to be illuminated.
FIG. 10
is a schematic diagram to show the major part of the illumination apparatus suggested in the above Japanese application. In
FIG. 10
, a polarization generator
20
has a first optical element
200
for creating a plurality of intermediate beams
202
(condensed images
203
) spatially separated from each other, from light emitted from a light source section
10
consisting of a light source
101
and a parabolic mirror
102
, and a second optical element
300
placed near the position of convergence of the plurality of intermediate beams
202
and having a polarization separating unit array
320
consisting of a polarization separating film array
330
for spatially separating each intermediate beam
202
into two kinds of polarized light beams having respective polarization directions different from each other, a half-wave phase plate array
381
for aligning the polarization direction of the polarized beams of the first kind with that of the polarized beams of the second kind to form linearly polarized light beams of one kind, and a reflecting surface array
332
, a condenser lens array
310
consisting of a plurality of condenser lenses
311
, and an exit-side lens.
In the first optical element
200
, beam splitting lenses
201
arranged adjacently in the Y-direction are placed in a shifted state from each other in the X-direction each by a distance corresponding to approximately a half length of the array pitch thereof in the X-direction, which can improve nonuniformity of light intensity distribution of the light from the light source. In addition, the above Japanese application also discloses a color liquid crystal projector having the polarization generator illustrated in
FIG. 10
, a color separating means, three liquid crystal panels, a color combining means, and a projection lens.
In each of the embodiments proposed in the above Japanese application, there is no numerical data of the illumination optical system disclosed and it is thus indefinite as to the relation between the focal length of the parabolic reflector and the focal length of the first lens array and the like.
For this reason, designed values (configurations) for yielding the best illumination efficiency were unknown. The projection type display device of
FIG. 12
in the above Japanese application also had the drawback of poor light-condensing nature of light onto the entrance pupil of the projection lens, because there was no condenser lens near the liquid crystal panel.
Further, it also describes nothing about detailed structure of the microlenses used for increasing an aperture ratio of the liquid crystal panel.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an illumination apparatus and a projection type display apparatus with higher light utilization efficiency than before.
An illumination apparatus according to one aspect of the present invention is an illumination apparatus comprising a light-collecting reflector, a light source placed at a position of a focal point of the reflector, a first lens array for condensing light reflected by the reflector, a second lens array disposed at or near a position of a rear focal point of the first lens array, and an optical system for illuminating a surface to be illuminated, with multiple beams from the second lens array, said illumination apparatus satisfying the following condition:
0.7<
K
1
<1.3 (1)
where K
1
=(Larc×flyf
1
/2fm)/(Lfly
2
p/2)
where Larc: a length of a light-emitting portion of said light source along a direction of the optical axis,
flyf
1
: a focal length of said first lens array,
fm: a focal length of said light-collecting reflector, and
Lfly
2
p: a length along a longitudinal direction of an entrance surface of each lens of said second lens array.
Another illumination apparatus according to a further aspect of the present invention is an illumination apparatus comprising a first lens array for condensing light from a light source, a second lens array disposed at or near a position of a rear focal point of the first lens array, a first optical system for condensing multiple beams from the second lens array, and a second optical system for illuminating a surface to be illuminated, with said multiple beams from the first optical system, said illumination apparatus satisfying the following condition:
0.95<
K
2
<1.15 (2)
where K
2
=(Lfly
1
p×fc
12
/flyf
2
)/Ldsp
where Ldsp: a diagonal length of said surface to be illuminated,
flyf
2
: a focal length of said second lens array,
fc
12
: a composite focal length of said first lens system and said second lens system, and
Lfly
1
p: a diagonal length of each lens of said first lens array.
Another illumination apparatus according to a further aspect of the present invention is an illumination apparatus comprising a first lens array for condensing light from a light source, a second lens array disposed at or near a position of a rear focal point of the first lens array, a first optical system for condensing multiple beams from the second lens array, and a second optical system for illuminating a surface to be illuminated, with the multiple beams from the first optical system, said illumination apparatus satisfying the following condition:
0.9<
K
3
<1.4 (3)
where K
3
=fc
1
/fc
2
where fc
1
: a focal length of said first optical system, and
fc
2
: a focal length of said second optical system.
Another illumination apparatus according to a further aspect of the present invention is an illumination apparatus comprising a first lens array for condensing light from a light source, a second lens array disposed at or near a position of a rear focal point of the first lens array, a first optical system for condensing multiple beams from the second lens array, and a second optical system for illuminating a display device with the multiple beams from the first optical system, said display device compri
Mack Ricky
Morgan & Finnegan , LLP
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