Optics: image projectors – Temperature control – Blower
Reexamination Certificate
1998-11-19
2001-09-18
Dowling, William (Department: 2851)
Optics: image projectors
Temperature control
Blower
C353S058000
Reexamination Certificate
active
06290360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal projector for displaying a picture on a screen by projecting light rays emitted by a light source onto three liquid crystal panels and transmitted by the three liquid crystal panels, and a projection lens unit, an optical unit and a cooling system to be employed in the liquid crystal projector.
2. Description of the Related Art
A prior art liquid crystal projector provided with three liquid crystal panels is disclosed in, for example, JP-A No. 6-289392. This prior art liquid crystal projector comprises, as principal components, a light source, a cold mirror, a blue light reflecting dichroic mirror (hereinafter referred to as “B light reflecting dichroic mirror”), a green light reflecting dichroic mirror (hereinafter referred to as “G light reflecting dichroic mirror”), image reflecting mirrors, a red-light liquid crystal panel (hereinafter referred to as “R liquid crystal panel”), a green-light liquid crystal panel (hereinafter referred to as “G liquid crystal panel”), a blue-light liquid crystal panel (hereinafter referred to as “B liquid crystal panel”), a combining dichroic prism and a projection lens. Light rays emitted by the light source are divided into R, G and B light rays by the light transmitting and reflecting agencies of the cold mirror, the B light reflecting dichroic mirror and the G light reflecting dichroic mirror, the light rays are reflected by the image reflecting mirrors toward the R, G and B liquid crystal panels. The light rays traveled through the R, G and B liquid crystal panels are combined by the dichroic prism and a color picture is projected through the projection lens in an enlarged color picture on a screen.
Such a known, commercialized liquid crystal projector employs three 1.3 in. liquid crystal panels. is formed in a compact construction and is capable of displaying pictures in a high definition.
The foregoing liquid crystal projector is provided with a cooling system for suppressing the temperature rise of the liquid crystal panels.
Referring to
FIG. 1
showing a known liquid crystal projector in a side view, a cooling fan
81
(an axial fan in this liquid crystal projector) is disposed below three 1.3 in. liquid crystal panels (only liquid crystal panels
14
and
18
are shown) to blow air toward the liquid crystal panels including the liquid crystal panels
14
and
18
to suppress the temperature rise of the liquid crystal panels including the liquid crystal panels
14
and
18
. Since the liquid crystal panels including the liquid crystal panels
14
and
18
are exposed directly to air delivered by the cooling fan
81
, the liquid crystal panels including the liquid crystal panels
14
and
18
can effectively cooled. In
FIG. 1
, indicated at
27
is a projection lens.
The outside size in a horizontal plane of this liquid crystal projector provided with the three 1.3 in. liquid crystal panels excluding a projecting part of the projection lens projecting from a case is 245 mm by 329 mm, and the overall outside size in a horizontal plane of the liquid crystal projector including the projecting part of the projection lens is 245 mm by 380 mm. Such a large overall outside size of the liquid crystal projector is a problem in storing and carrying the liquid crystal projector, and the reduction of the overall outside size of the liquid crystal projector has been desired.
The inventors of the present invention examined a concept about miniaturization necessary to realize a liquid crystal projector more compact than the prior art liquid crystal projector and found that a liquid crystal projector provided with three liquid crystal panels must be formed in the smallest possible outside size suitable for storing the liquid crystal projector in a prevalently used storage cabinet and for carrying the same in a prevalently used carrying case.
The known liquid crystal projector shown in
FIG. 1
has a height L
2
equal to the sum of the height of a part including the projection lens
27
and the liquid crystal panels
14
and
18
, and the height of the cooling fan
81
. The liquid crystal projector has a dead space under the projection lens
27
, which increases the overall height of the liquid crystal projector.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide a liquid crystal projector of an outside size capable of being stored in a prevalently used storage cabinet and of being carried in a prevalently used carrying case.
Another object of the present invention is to provide a liquid crystal projector having a small height and formed in a compact construction.
A third object of the present invention is to provide a projection unit and an optical unit effective in forming a liquid crystal projector in a compact construction.
A fourth object of the present invention is to provide a cooling system capable of efficiently cooling a liquid crystal projector.
With the foregoing objects in view, the present invention provides a liquid crystal projector having a size in a horizontal plane substantially equal to an A4 folder size, i.e., the size of folders for holding papers of the trimmed sheet size A4. The A4 folder size is 263 mm by 318 mm. The liquid crystal projector of the present invention subjects light rays emitted by a light source to color separation to divide the light rays, projects the divided light rays on a first liquid crystal panel, a second liquid crystal panel and a third liquid crystal panel, combines the light rays traveled through the first, the second and the third liquid crystal panel, and projects the combined light rays on a screen through a projection lens. The outside size in a horizontal plane of the liquid crystal projector is the outside size of a case serving as a housing for the liquid crystal projector. The outside size in a horizontal plane of the liquid crystal projector may be the sum of the size of the case and that of a part projecting from the case. The size of the first, the second and the third liquid crystal panel is 0.9 in. or below. The distance between the display surface of the liquid crystal panel disposed substantially perpendicularly to the optical axis of the projection lens and the extremity of the projection lens is about 146 mm or below. The liquid crystal projector is provided with a color combining optical system including a cross dichroic prism for color combination. The cross dichroic prism has a size in a horizontal plane of 32 mm by 32 mm or below.
A liquid crystal projector according to the present invention comprises a color separation optical system comprising a cross dichroic prism, and a first dichroic mirror, a second dichroic mirror, a first mirror, a second mirror and a third mirror arranged around the cross dichroic prism, an illuminating system comprising a light source, a polarizing device and an optical integrating means, liquid crystal and a projection lens unit comprising a light source power supply for supplying power to the light source, and a projection lens unit comprising a plurality of liquid crystal panels, a cross dichroic prism and a projection lens, in which the projection lens unit, the color separating optical system, the illuminating optical system, and the light source power supply are arranged in that order.
A liquid crystal projector according to the present invention comprises a color separating optical system comprising a first dichroic mirror, a second dichroic mirror, and a first mirror, a second mirror and a third mirror arranged around a cross dichroic mirror, an illuminating optical system comprising a light source, a polarizing device, and an optical integrating means, a light source power supply for supplying power to the light source, and a projection lens unit comprising a plurality of liquid crystal panels, a cross dichroic prism and a projection lens, in which the combination of the projection lens unit and the color separating optical system, the illuminating optical system and the light source power suppl
Deguchi Masaharu
Fukatsu Makoto
Fuse Kenji
Hagura Shigehisa
Hoshino Takeshi
Dowling William
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
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