Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
2000-10-13
2002-04-02
Elms, Richard (Department: 2824)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C349S005000, C349S010000, C349S200000, C353S094000, C353S102000, C353S082000
Reexamination Certificate
active
06365526
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an optical illumination system which can efficiently irradiate light upon a light valve (display device) such as, for example, a liquid crystal display panel and a projection apparatus which includes an optical illumination system of the type mentioned.
Recently, display apparatus such as a projector apparatus, a television receiver and a display unit for a computer which use, for example, an optical element such as a liquid crystal display panel which is a light valve have been popularized in wide fields.
Such a projection apparatus which uses a liquid crystal display panel as described above spectrally decomposes light emitted from a light source into lights of the primary colors and introduces the lights of the primary colors into the liquid crystal display panel. The liquid crystal display panel optically modulates the lights of the primary colors with a video signal inputted thereto and composes the modulated lights of the primary colors to produce a color video signal.
The color video signal is projected in an enlarged scale onto a screen through a projecting lens.
In an optical system of such display apparatus as described above, an ultra high pressure mercury lamp, a metal halide lamp and so forth are used frequently as a light source due to their favorable color rendering properties.
The light sources mentioned, however, do not form an ideal point source of light and emit a luminous flux which has a large divergence angle.
Meanwhile, it is demanded that an illumination optical system used for an optical system to which the present invention is applied can irradiate a luminous flux emitted from a light source upon a liquid crystal display panel efficiently and uniformly.
However, a luminous flux generated by a light source used popularly has a large divergence angle as described above.
Therefore, it is difficult for a luminous flux emitted from the light source to be irradiated efficiently upon the liquid crystal display panel.
As means for causing a luminous flux emitted from a light source and having a large divergence angle in this manner to be irradiated efficiently upon a liquid crystal display panel, it is conventionally known, for example, to use a lens array having a structure which includes a large number of small lenses arranged in a grid-like arrangement or a like element to converge a luminous flux to reach the liquid crystal display panel with a uniform illuminance distribution.
An example of a typical projection apparatus which uses a lens array of the type described above is described below with reference to FIG.
1
.
A light source
3
includes, for example, an ultra high pressure mercury lamp
3
b
disposed at a focal position of a paraboloid mirror
3
a
and emits a luminous flux having a predetermined convergence angle through an aperture thereof.
Of the luminous flux emitted from the light source
3
, unnecessary rays of light in an infrared region (IR) and an ultraviolet region (UV) are intercepted by an UV/IR cut filter
5
while only effective rays of light are introduced into a first optical block
1
positioned rearwardly of the aperture of the light source
3
.
The first optical block
1
is composed of an optical element including a first lens array
21
on which a plurality of convex cell lenses
21
a
having an outer profile substantially similar to an aspect ratio of effective apertures of liquid crystal display panels
45
,
49
and
53
as light valves (optical spatial modulation elements) are arranged in a grid-like arrangement.
A second lens array
23
of a second optical block
2
disposed rearwardly of the first optical block
1
has a plurality of convex cell lenses
23
a
formed on the incoming side thereof and has a single convex surface
23
f
formed on the outgoing side thereof and serving as a first condensing component.
A pair of dichroic mirrors
14
and
27
for decomposing light emitted from the light source
3
into color lights of red, green and blue are disposed between the second lens array
23
and the effective apertures of the liquid crystal display panels
45
,
49
and
53
.
In the arrangement shown in
FIG. 1
, the red light R is reflected by the dichroic mirror
14
while the green light G and the blue light B are transmitted through the dichroic mirror
14
. The red light R reflected by the dichroic mirror
14
has an advancing direction which is bent by 90 degrees by a mirror
15
, and is then converged by a condensing lens
51
and introduced into the liquid crystal display panel
53
for red.
Meanwhile, the green light G and the blue light B having been transmitted through the dichroic mirror
14
are decomposed by the dichroic mirror
27
. In particular, the green light G is reflected by the dichroic mirror
27
so that its advancing direction is bent by 90 degrees, and is introduced into the liquid crystal display panel
49
for green through a condensing lens
47
. Meanwhile, the blue light B is transmitted through the dichroic mirror
27
and advances straightforwardly, and is introduced into the liquid crystal display panel
45
for blue by relay lenses
29
and
33
, a condensing lens
43
and mirrors
31
and
35
.
A polarizing plate (not shown) for polarizing incoming light to a fixed polarization direction is disposed on the incoming side of each of the liquid crystal display panels
45
,
49
and
53
, and another polarizing plate (not shown) which only transmits outgoing light having a predetermined polarization plane is disposed rearwardly of each of the liquid crystal display panels
45
,
49
and
53
. Each of the liquid crystal display panels
45
,
49
and
53
thus modulates the intensity of light with a voltage of a circuit for driving liquid crystal.
The lights of the colors optically modulated by the liquid crystal display panels
45
,
49
and
53
are composed by a dichroic prism
41
serving as optical composing means. The dichroic prism
41
reflects, with its reflecting face
41
a
, the red light R and reflects, with its reflecting face
41
b
, the blue light B both toward a projection lens
13
.
Meanwhile, the green light G is transmitted through the reflecting faces
41
a
and
41
b
. Consequently, the red light R, green light G and blue light B are composed into a single luminous flux on an optical axis and projected in an enlarged scale to a screen
102
by the projection lens
13
.
Now, a configuration of the lens arrays
21
of the first optical block
1
and the lens arrays
23
of the go second optical block
2
is described in more detail with reference to
FIGS. 2 and 3
.
First,
FIG. 2
illustrates an example of formation of a luminous flux principally by an optical characteristic of the first optical block
1
. A luminous flux L emitted from a light source is decomposed by the individual cell lenses
21
a
of the first lens array
21
and forms, after it goes out from the first optical block
1
, images corresponding to the cell lenses
21
a
of the first lens array
21
in the proximity of the second optical block
2
. Thereafter, the luminous flux is introduced into the condensing lens
47
, which serves as a second condensing component, by the convex surface
23
f
of the second lens array
23
. An image of the light source is reformed in the proximity of the pupil of the projection lens
13
shown in
FIG. 1
by the condensing lens
47
.
It is to be noted that reference numerals
41
and
49
denote a dichroic prism and a crystal display panel, respectively.
FIG. 3
illustrates an example of formation of a luminous flux by the second optical block
2
. The divergence angle &thgr; with which a luminous flux can be taken in by the illumination system is controlled by suitably setting the outer profile dimensions of the cell lenses
23
a
and the distance between the first lens array
21
and the second lens array
23
.
The thus taken in luminous flux within the divergence angle is introduced into the condensing lens
47
, which serves as a second condensing component, by the convex surface
23
f
which serves as a fi
Kanamori Tatsuru
Kita Koji
Shinoda Makoto
Sugihara Kenji
Elms Richard
Luu Pho
Maioli Jay H.
Sony Corporation
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