Illumination – Plural light sources – With modifier
Reexamination Certificate
1999-10-29
2002-08-13
O'Shea, Sandra (Department: 2875)
Illumination
Plural light sources
With modifier
C362S268000, C362S332000, C359S622000, C359S618000
Reexamination Certificate
active
06431727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an illuminating device and a projection type display apparatus such as a liquid crystal projector using the same.
2. Related Background Art
Heretofore, as the illuminating device of a projection type display apparatus, one as shown in
FIG. 6
of the accompanying drawings which comprises a combination of a light-emitting tube
1
and a parabolic mirror
19
has been popular.
In
FIG. 6
, white light emitted from the light-emitting portion
1
c
of the light-emitting tube
1
(light source) is converted into a substantially parallel light by the parabolic mirror
19
, and the light source image of the light-emitting tube
1
is formed at the center of each frame of a second lens array
4
by a first lens array
3
. The focal lengths of the first lens array
3
and the second lens array
4
are substantially equal to each other, and the spacing between the first lens array
3
and the second lens array
4
is a spacing substantially equal to the focal length of the first lens array
3
.
The light beam condensed by the first lens array
3
is separated into a P wave and an S wave by the polarization separating layer
5
B of a polarization converting element
5
, and the S wave is reflected by the polarization separating layer
5
B, and is further reflected by an adjacent polarization separating layer
5
B, whereby it emerges from the gap of a &lgr;/2 phase difference plate
5
A disposed like a bamboo-blind at the emergence side of the polarization converting element
5
. The P wave is transmitted through the polarization separating layer
5
B and is further transmitted through the &lgr;/2 phase difference plate
5
A, whereby it is phase-converted and emerges with the direction of its polarization axis uniformized to the S wave. Thereby the light beam emerging from the polarization converting element
5
all become polarized lights (S waves) having polarization axes in the same direction. The reference character
5
C designates a bamboo-blind-like light-intercepting plate.
The light beam emerging from the polarization converting element
5
is deflected by a first condenser lens
6
, and is modulated into R, G and B colors, which are superposed on the display portions
8
R,
8
G and
8
B of an image modulating device comprising a liquid crystal panel. That is, of the light beam emerging from the first condenser lens
6
, red light is reflected by a dichroic mirror DM
1
and the remaining green light and blue light are transmitted therethrough. The red light reflected by the dichroic mirror DM
1
is directed to the display portion
8
R of an image modulating device for red through the intermediary of a reflecting mirror M
1
and a second condenser lens
7
R. The light transmitted through the dichroic mirror DM
1
is separated into green and blue by a dichroic mirror DM
2
. The green light is reflected by the dichroic mirror DM
2
, and is directed to the display portion
8
G of an image modulating device for green through a second condenser lens
7
G. The blue light transmitted through the dichroic mirror DM
2
is condensed by a third condenser lens
11
, is reflected by a reflecting mirror M
2
, and is directed to the display portion
8
B of an image modulating device for blue by a relay lens
12
through the intermediary of a reflecting mirror M
3
and a second condenser lens
7
B.
In
FIG. 6
, the reference character P
1
designates an incidence side polarizing plate, and the reference character P
2
denotes an emergence side polarizing plate. The second condenser lenses
7
R,
7
G and
7
B are for condensing the light beam emerging from the first condenser lens
6
onto the entrance pupil of a projection lens
10
. A cross dichroic prism
9
is disposed between the display portions
8
R,
8
G,
8
B of the image modulating devices and a projection lens
10
to effect color combination. The projection lens
10
is designed to be telecentric relative to the display portions
8
R,
8
G and
8
B of the image modulating devices, and is designed such that the angle of incidence on the dichroic film surface of the cross dichroic prism
9
is constant everywhere on the dichroic film, and is designed such that the color irregularity by any change in the angle of incidence of the dichroic film does not occur. The light beams modulated by the display portions
8
R,
8
G and
8
B of the image modulating devices are color-combined by the cross dichroic prism
9
, and are enlargedly projected onto a screen, not shown, by the projection lens
10
.
Also, a projection type display apparatus using a light source device including a combination of a plurality of light sources, a plurality of reflecting mirrors and a pair of lens arrays to increase the brightness of an image on the screen is proposed in Japanese Laid-Open Patent Application No. 6-265887, and it is conceived to use such a light source device in the liquid crystal projector of FIG.
6
.
If two light sources and a reflecting mirror for disposing the two light sources at a focal position are simply arranged in front of a first lens array
3
, unless the focal length of the reflecting mirror is greatly shortened, a desired angle for introducing the lights emitted from the light sources is not obtained, and consequently the degree of parallelism of the light beams entering the first lens array
3
is aggravated, and when the light source portion of the aforementioned Japanese Laid-Open Patent Application No. 6-265887 is used as the light source portion of
FIG. 6
, the eclipse at the light intercepting portion
5
C of a polarization converting element
5
increases and the illumination efficiency becomes reduced. Therefore, it has been found that in spite of the two light sources being used, the increase in quantity of light is only up to the order of 40% as compared with a case where a light source is used.
SUMMARY OF THE INVENTION
It is the object of the present invention to realize an improvement in the illuminating efficiency when a plurality of light sources are used.
To solve the above-noted problem, in the present invention, in an illuminating device wherein a plurality of light sources are arranged in a direction perpendicular to an optical axis, an illuminating optical system for illuminating a surface to be illuminated with lights from said plurality of light sources, said illuminating optical system including an optical system in which an action of compressing the lights in a direction of arrangement of said plurality of light sources is stronger than an action of compressing the lights in a direction perpendicular to the direction of arrangement of said plurality of light sources. The illuminating device of the present invention is an illuminating device wherein lights emitted from a plurality of light sources are made to enter a lens array system and illumination is effected by the lights from this lens array system, an optical system in which the action of compressing the lights in the direction of arrangement of the plurality of light sources is greater than the action of compressing the lights in a direction perpendicular thereto is provided between the plurality of light sources and the lens array system. The lens array system is provided with at least one fly-eye lens or at least one lenticular lens.
The illuminating device of the present invention is an illuminating device in which lights emitted from a plurality of light sources are substantially parallel lights and are made to enter a lens array system, and illumination is effected by the lights from the lens array system, characterized in that an optical system in which the action of compressing the incident light in the direction of arrangement of the plurality of light sources is greater than the action of compressing the incident light in a direction perpendicular thereto is provided between the light sources and the lens array system.
In the above-described illuminating device, the plurality of light sources are arranged in the lengthwise direction of a frame of lens constituting the
Okuyama Atsushi
Sugawara Saburo
DelGizzi Ronald E.
Morgan & Finnegan , LLP
O'Shea Sandra
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