Optics: image projectors – Housing
Reexamination Certificate
2003-09-22
2004-10-26
Dowling, William C. (Department: 2851)
Optics: image projectors
Housing
Reexamination Certificate
active
06808273
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a projector and more particularly to a projector having a cooling mechanism to cool a light source provided in a housing.
A projector is designed for generating an optical image from image data provided by a personal computer or a video camera and projecting it on a screen for display.
Such a projector is disclosed in Japanese Patent Laid-open Publication No. Hei 10-90811 which has an air exhaust opening provided next to projection lens in the front side of a housing for exhausting hot air which was used for cooling by an exhaust fan, hence minimizing the effect of hot exhaust air and noise from the exhaust fan and the effect of unwanted light leaked from a light source which may annoy viewers. This projector is referred to as a first prior art hereinafter.
Another prior art may be featured with a closable lens cover for closing and protecting the front side of the projection lens. For example, some projectors of a type where a lens window for a projection lens is openably closed with a slidable lens cover are disclosed in Japanese Patent Laid-open Publication No.2000-162703, 2001-272648, and 2001-249402. These projectors are referred to as a second prior art hereinafter.
Also, a liquid crystal projector which has a shutter mechanism for protecting the front side of a projection lens is disclosed in Japanese Patent Laid-open Publication No.2001-242542. This liquid crystal projector is referred to as a third prior art hereinafter.
However, the first prior art has the air exhaust opening for exhausting hot air provided next to the projection lens in the front side of its housing, hence permitting the hot air from the air exhaust opening to run across the optical path of projected light from the projection lens and generate undesired shimmers (heat wave) in the optical image projected on the screen.
The generation of shimmers in the optical image will now be explained in detail referring to
FIGS. 13 and 14
. As shown in
FIG. 13
the air for cooling is introduced into the interior of a main body
102
from two air inlets
109
and
122
provided in the right side and the rear side of a housing
103
respectively and directed towards a lamp
120
by the action of an exhaust fan
121
. Hot air which was used for cooling the lamp
120
is exhausted from an air outlet
108
provided in the front side of the housing
103
. The hot air indicated by arrow A may flow across the optical path of a projected light
123
released from a projection lens
105
. As the projected light
123
is interrupted particularly at an area adjacent to the air output
108
by the hot air from the air outlet
108
, its image on a screen
131
may fluctuate significantly at the right
132
as shown in FIG.
14
.
The second and third prior arts also fail to eliminate the above drawback.
SUMMARY OF THE INVENTION
It is hence an object of the present invention to provide a projector which can prevent hot air exhausted from the air outlet from running across the light path of the light projected with the projection lens can eliminate the generation of shimmers in the projected image.
A projector in accordance with an aspect of the present invention comprises a projection lens, an air outlet and a lens cover.
The projection lens projects an optical image using a light emitted by a light source.
The air outlet is for exhausting hot air which was used for cooling the light source to the outside.
The lens cover protects the projection lens.
The lens cover can be held between the air outlet and the projection lens.
The foregoing arrangement allows the lens cover to be turned open and held between the air outlet and the projection lens when the projection of an image is desired. Thus, the lens cover can prevent hot air exhausted from the air outlet from running across the light path of the light projected with the projection lens and can eliminate the generation of shimmers in the projected image.
REFERENCES:
patent: 5287132 (1994-02-01), Suzuki et al.
patent: 5347324 (1994-09-01), Sasaki et al.
patent: 6190015 (2001-02-01), Tsai et al.
patent: 6238050 (2001-05-01), Konuma et al.
patent: 10-090811 (1998-04-01), None
patent: 2000-162703 (2000-06-01), None
patent: 2001-242542 (2001-09-01), None
patent: 2001-249402 (2001-09-01), None
patent: 2001-272648 (2001-10-01), None
Crowell & Moring LLP
Dowling William C.
Funai Electric Co. Ltd.
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