Optics: image projectors – Unitary plural refracting surfaces
Reexamination Certificate
2000-02-17
2002-10-01
Adams, Russell (Department: 2851)
Optics: image projectors
Unitary plural refracting surfaces
C353S020000, C353S069000, C353S102000, C349S005000, C349S009000, C359S443000, C359S651000
Reexamination Certificate
active
06457832
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an illumination apparatus and a projection apparatus having it and, more particularly, to those suitably applicable to liquid crystal projectors, for example, of a single panel type or a three panel type capable of implementing illumination with high uniformity and with little illuminance unevenness on a projection screen.
2. Related Background Art
A variety of proposals have been made heretofore as to the technology of projectors constructed to enlarge and project an image formed on a display element such as liquid-crystal light valves (a liquid crystal panel) or the like, onto a display surface such as a screen or the like.
The liquid crystal projectors are constructed to illuminate a liquid crystal display element with light from an illumination system and enlarge and project light with image information, modulated by the liquid crystal light valves and transmitted by the element, through a projection lens onto the screen. In the case of U.S. Pat. No. 5,098,184, for example, an integrator comprised of a combination of two lens arrays set in series, as illustrated in FIG.
12
, was used as a means for uniforming the light amount distribution of the illumination light on the liquid crystal display element.
In
FIG. 12
, reference numeral
101
designates a white light source,
102
a condenser lens system which is a combination of a mirror with a lens,
103
a first lens array consisting of a plurality of lenses,
104
a second lens array consisting of a plurality of lenses,
105
a condenser lens,
106
a condenser lens,
107
a liquid crystal panel, and
108
a projection lens. In this illumination system, light from the condenser lens system
102
is separated into a plurality of beams in the first lens array
103
, and the plurality of beams separated are made to overlap each other on the liquid crystal panel
107
by the second lens array and the relay lens system consisting of the condenser lens
105
and the condenser lens
106
, whereby an almost uniform illumination area is created on the liquid crystal panel
107
. Since the shape of this illumination area is similar to the shape of the individual lenses of the first lens array
103
, the outline shape of the individual lenses of the first lens array
103
is normally a rectangular shape similar to the shape of the liquid crystal panel
107
, so as to lay the illumination area on the liquid crystal panel.
In the illumination system of
FIG. 12
, let Df
1
be the size of the first fly's eye lens
103
, D
1
be the size of the liquid crystal panel
107
, ff
2
be the focal length of the individual lenses of the second lens array
104
, fi be the focal length of the condenser lens
105
, and Mc be a magnification of the condenser lens
106
acting on the light from the condenser lens
105
. Then the following relation is met:
Df
1
=(
D
1
/
Mc
)×(
ff
2
/
fi
)=
D
1
×
ff
2
/
fr
(a1).
Here fr=Mc×fi, which is the composite focal length of the relay lens system. In the illumination system illustrated in
FIG. 12
, each of the condenser lenses is a lens having a positive refracting power. If these lenses are spaced with an unrepresented color separation system in between it will be difficult to correct well for curvature of field appearing in this relay lens system and transverse aberration will appear in the periphery of the optical system. In the structure as defined by above Eq. (a1), there occurs deviation between the beams superimposed in the illumination area because of transverse aberration remaining in the relay lens system, which poses a problem of illumination nonuniformity in the edge part of the illumination area.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an illumination apparatus and a projection apparatus capable of illuminating a surface to be illuminated, more uniformly than before.
An illumination apparatus according to one aspect of the present invention is an illumination apparatus for illuminating an area to be illuminated, of a rectangular shape with light from a light source via a first lens array, a second lens array, and a condensing optical system arranged in the stated order from the side of the light source, the illumination apparatus satisfying the following conditions:
Dfx
>(
Dpx+&dgr;x
)×
ff
2
/
fr
Dfy
>(
Dpy+&dgr;y
)×
ff
2
/
fr
where Dpx is a length along a longitudinal direction of said area to be illuminated, Dpy is a length along a transverse direction thereof, ff
2
is a focal length of individual lenses forming the second lens array, fr is a focal length of said optical system, &dgr;x is a width of transverse aberration in said longitudinal direction against an object at infinity, caused by the optical system, &dgr;y is a width of transverse aberration in said transverse direction, caused by the optical system, Dfx is a length along a longitudinal direction of individual lenses of the first lens array, and Dfy is a length along a transverse direction of the lenses of the first lens array.
Another illumination apparatus according to a further aspect of the present invention is an illumination apparatus for illuminating an area to be illuminated, of a rectangular shape with light from a light source via a first lens array, a second lens array, and a condensing optical system arranged in the stated order from the side of the light source, the illumination apparatus satisfying the following conditions:
Dfx
>(
Dpx+&dgr;x
)×
Sr
Dfy
>(
Dpy+&dgr;y
)×
Sr
where Dpx is a length along a longitudinal direction of said area to be illuminated, Dpy is a length along a transverse direction thereof, Sr=L
2
/L
1
wherein L
1
is a distance from the first lens array to a position of a principal point on the side of said light source, of a composite system of the second lens array and the condensing optical system and L
2
is a distance from a position of a principal point on the side of said area to be illuminated, of said composite system to said area to be illuminated, &dgr;x is a width of transverse aberration in said longitudinal direction against an object at infinity, caused by said condensing optical system, &dgr;y is a width of transverse aberration in said transverse direction, caused by said condensing optical system, Dfx is a length along a longitudinal direction of individual lenses of the first lens array, and Dfy is a length along a transverse direction of the lenses of the first lens array.
Another illumination apparatus according to a further aspect of the present invention is an illumination apparatus for illuminating an area to be illuminated, of a rectangular shape with light from a light source via a first lens array, a second lens array, and a condensing optical system arranged in the stated order from the side of the light source, wherein when weighted mean widths of transverse aberration are computed by the following equations:
δ
x
_
=
2
(
∑
i
δ
xi
2
·
Epi
∑
i
Epi
)
1
/
2
δ
y
_
=
2
(
∑
j
δ
yj
2
·
Epj
∑
j
Epj
)
1
/
2
where &dgr;x is a width of transverse aberration in said longitudinal direction against an object at infinity, caused by said optical system, &dgr;y is a width of transverse aberration in said transverse direction, caused by said optical system, Ep is a normalized intensity distribution at an entrance pupil of said optical system, &dgr;xi is a transverse aberration amount of a ray passing a center of the i-th lens, when counted from an end in said longitudinal direction, out of individual lenses forming said first lens array at the time of incidence to the pupil of said condensing optical system, &dgr;yj is a transverse aberration amount of a ray passing a center of the j-th lens in the transverse direction out of the individual lenses forming the first lens array at the time of incide
Adams Russell
Koval Melissa J
Morgan & Finnegan , LLP
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