Optics: image projectors – Housing
Reexamination Certificate
2002-12-26
2004-03-23
Dowling, William (Department: 2851)
Optics: image projectors
Housing
C353S057000
Reexamination Certificate
active
06709115
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a projector which projects an image on a screen.
Recently, a projector is widely used for various applications, and it is desired to develop a compact projector having superior portability. Generally, in order to control the rise in the temperature of the projector due for example to a light source, the heated air in the projector must be exhausted by means of an exhaust fan. In many projectors, the exhaust fan and an exhaust port are closely placed, because of the demand for reducing the size of the projector.
There is also type of projector having an externally attached duct for preventing the exhausted air from blowing toward a person beside the projector.
FIGS. 16A and 16B
are respectively a perspective view and a side view showing an outer shape of a projector disclosed in a Japanese Laid-Open Patent Publication HEI 9-319007. As shown in
FIG. 16A
, a projector
101
has a projection lens
103
provided on the front of an enclosure
102
and an exhaust port
104
provided on the side of the enclosure
102
. A duct
105
is detachably attached to the exhaust port
104
. The duct
105
directs the exhausted air upward, so that the exhausted air does not blow toward the person beside the projector.
As shown in
FIG. 16B
, the duct
105
is attached to the enclosure
102
, by inserting engagement pieces
106
formed at the end of the duct
105
into grooves
107
formed around the exhaust port
104
, and by rotating the duct
105
in one direction. The duct
105
is detached from the enclosure
102
, by rotating the duct
105
in a reverse direction, and by removing the engagement pieces
106
from the grooves
107
.
FIGS. 17A and 17B
are respectively a perspective view and a side view showing an outer shape of another conventional projector. In addition to the components described with reference to
FIGS. 16A and 16B
, inlet ports
201
are formed on the top of the enclosure
102
. The outside air is taken through the inlet ports
201
and the inside air is exhausted through the exhaust port
104
. Thus, the cooling effect is enhanced.
However, the above described conventional projectors have the following problems.
First, the projector in which the exhaust fan and the exhaust port are closely placed has a problem that a noise called “wind noise” is generated. In order to restrict the wind noise being generated, it is necessary to provide a large space between the exhaust fan and the exhaust port. However, if such a space is provided, it becomes difficult to reduce the size of the projector.
Additionally, in order to keep the exhaust fan operating properly, it is necessary to keep the temperature of a fan motor built in the exhaust fan within a suitable temperature range. Thus, generally, a reflector or the like is provided between a lamp used as a light source and the exhaust fan, to shield the exhaust fan from the radiation from the lamp. In order to reduce the number of components of the projector, it is preferable to eliminate such a reflector. However, to eliminate the reflector, the distance between the lamp and the exhaust fan must be increased, and therefore it becomes difficult to reduce the size of the projector.
Further, the projector
101
having the externally attached duct
105
as shown in
FIGS. 16A through 17B
is not convenient to use, since the duct
105
needs to be attached to the projector and the direction of the duct
105
needs to be adjusted each time the projector
101
is used. Moreover, this projector
101
has another problem that the attached duct
105
impairs the appearance of the projector
101
.
In addition, the projector having the inlet ports as shown in
FIGS. 17A and 17B
has a problem that the dust or the like enters into the projector through the inlet ports when the projector is not used, and degrades the displayed image.
SUMMARY OF THE INVENTION
This invention is intended to solve the above described problems, and an object of the present invention is to provide a compact projector having excellent portability, to restrict the noise generated in the projector, and to reduce the number of components of the projector.
A projector according to the invention comprises an image projection unit which projects an image and has a light source. The projector further comprises a first casing in which the image projection unit is mounted, and a second casing combined with the first casing thereby to constitute an enclosure enclosing the image projection unit. The second casing is movable relative to the first casing, between an enlarging position where the volume of the enclosure is enlarged and a reducing position where the volume of the enclosure is reduced. The projector further comprises an exhaust port formed on the second casing.
According to one aspect of the invention, the projector further comprises an exhaust fan mounted to the first casing. The exhaust fan is made to rotate when the light source illuminates.
When the projector is not used, the size of the projector can be reduced by moving the second casing to the reducing position. Thus, the portability of the projector is enhanced. Further, when the projector is used, the second casing can be moved to the enlarging position to restrict the noise. Thus, the quietness of the projector is enhanced.
According to another aspect of the invention, the projector further comprises an exhaust fan mounted to the second casing. The distance between the exhaust fan and the light source is longer when the second casing is in the enlarging position than when the second casing is in the reducing position.
When the projector is not used, the size of the projector can be reduced by moving the second casing to the reducing position. Thus, the portability of the projector is enhanced. Further, when the projector is used, the temperature of the exhaust fan can be kept in a suitable range without using a reflector or the like, by moving the second casing to the enlarging position so that the distance between the exhaust fan and the light source increases. Thus, the reflector is eliminated and therefore the number of the components of the projector is reduced.
REFERENCES:
patent: 4925295 (1990-05-01), Ogawa et al.
patent: 5374969 (1994-12-01), Kyhl et al.
patent: 5820242 (1998-10-01), Rodriguez et al.
patent: 5842761 (1998-12-01), Futakami et al.
patent: 09-319007 (1997-12-01), None
patent: 10-090794 (1998-04-01), None
Chimura Kazuo
Oishi Toshihiro
Dowling William
Mitsubishi Denki Kabushi Kaisha
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