Optics: image projectors – Temperature control – Blower
Reexamination Certificate
2002-02-11
2003-11-04
Adams, Russell (Department: 2851)
Optics: image projectors
Temperature control
Blower
C353S119000, C353S058000
Reexamination Certificate
active
06641267
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a projection type display apparatus such as a liquid crystal projector, and more particularly to a technical field relating to a mechanism wherein a projection lens and an exhaust port for radiating heat of an internal heat source therethrough are disposed on a front wall of an outer housing.
Such a liquid crystal projector as shown in
FIGS. 15 and 16
which is an example of a projection type display apparatus conventionally is known. Referring to
FIGS. 15 and 16
, the conventional liquid crystal projector
81
shown includes an outer housing
82
in which an optical unit not shown is built. A projection lens
83
and an exhaust port
84
are provided in a leftwardly and rightwardly juxtaposed relationship on a front wall
82
a
of the outer housing
82
. An exhaust duct
87
having an exhaust fan
86
is disposed between the exhaust port
84
and a light source section
85
which is an internal heat source which generates heat of a high temperature in the optical unit. An image is projected from the projection lens
83
to a projection plane
88
such as a screen, and the exhaust fan
86
is operated so that heat of a high temperature generated by the light source section
85
and heat generated by a power supply section (not shown) and so forth which serve another internal heat source are exhausted in a direction parallel to an optical axis P of the projection lens
83
forwardly of the outer housing
82
from the exhaust port
84
through the exhaust duct
87
by the single exhaust fan
86
thereby to cool the internal heat sources such as the light source section
85
and the power supply section with air.
It is a possible idea to dispose the exhaust port
84
otherwise on a left or right side wall, a rear wall or the like of the outer housing
82
. However, since usually a viewer who enjoys an image projected to the projection plane
88
from the projection lens
83
is normally seated around the liquid crystal projector
81
other than the front of the liquid crystal projector
81
outside a projection light flux
89
of the image to be projected to the projection plane
88
from the projection lens
83
, a configuration wherein exhaust hot wind
90
of a high temperature generated by the light source section
85
and so forth is exhausted in the forward direction of the outer housing
82
which is the same direction as that of the projection direction of the projection lens
83
from the exhaust port
84
formed in the front wall
82
a
of the outer housing
82
is most preferable in that the exhaust hot wind
90
of a high temperature exhausted from the exhaust port
84
is not scattered to the viewer to provide a disagreeable feeling to the viewer or blasting sound generated by operation of the exhaust fan
86
is less likely to be offensive to the ear of the viewer.
However, with the system wherein heat generated by the light source section
85
, the power supply section and so forth is exhausted from the single exhaust port
84
through the signal exhaust duct
87
using the single exhaust fan
86
as in the conventional liquid crystal projector
81
, even if the heat of the light source section
85
can be exhausted comparatively efficiently, heat of such a power supply section as a setting power supply circuit board or a power supply circuit board for a light source section which is normally disposed at a position spaced away from the light source section
85
is cooled only by movement of the air in the inside of the outer housing
82
by operation of the single exhaust fan
86
, and the entire cooling efficiency in the liquid crystal projector
81
is low. Therefore, the conventional apparatus has a problem in that it is likely to suffer from deterioration in performance, reduction of the life and so forth because electronic parts such as an IC in the proximity of the power supply section and so forth have a bad influence of heat generated by the power supply section and so forth.
Further, with the structure that the projection lens
83
and the exhaust port
84
are disposed in a leftwardly and rightwardly juxtaposed relationship on the front wall
82
a
of the outer housing
82
as in the conventional liquid crystal projector
81
described above, since the optical unit in the outer housing
82
and the projection lens
83
are offset to one side with respect to the center of the outer housing
82
in the leftward and rightward widthwise direction, the liquid crystal projector
81
suffers from an imbalance in weight in a leftward and rightward widthwise direction. Therefore, as shown in
FIG. 17
, when the liquid crystal projector
81
is suspended on a ceiling in a room etc. by means of hanger elements
94
, the liquid crystal projector
81
is likely to be inclined in the leftward and rightward widthwise direction. Further, when an operator holds the liquid crystal projector
81
high above the head with both hands to perform an attaching operation of the liquid crystal projector
81
to the ceiling in order to hang the liquid crystal projector
81
on the ceiling, the liquid crystal projector
81
cannot be balanced readily in the leftward and rightward direction, and the attaching operation cannot be performed readily, or the balance may be lost, resulting in a falling or dropping accident of the liquid crystal projector
81
. Further, when the liquid crystal projector
81
is hung on the ceiling
93
in a room or the like by the hanger elements
94
, although generally an operator holds the liquid crystal projector
81
high above the head with both hands to set the projection lens
83
to a central position of the projection plane
88
such as a screen hung on a wall or the like, if the projection lens
83
is offset to one side of the outer housing
82
, then since the projection lens
83
is displaced to one side from the position of the head of the operator, the projection lens
83
cannot be positioned at the center of the projection plane
88
with reference to the position of the head of the operator. Therefore, the operability is very low.
Further, in the system wherein, during projection of an image to the projection plane
88
such as a screen by the projection lens
83
, the exhaust hot wind
90
of a high temperature generated from the light source section
85
, the power supply section and so forth is exhausted in a direction parallel to the optical axis P of the projection lens
83
forwardly of the outer housing
82
which is the same direction as that of the projection light flux
89
by the projection lens
83
as in the conventional liquid crystal projector
81
, particularly where a short focal length lens having a short focal length is used for the projection lens
83
and the projection angle (angle of view) &thgr; of the projection light flux
89
is great, part of the exhaust hot wind
90
is liable to advance into part of the projection light flux
89
.
Then, if the exhaust hot wind
90
advances into the projection light flux
89
, then there is the possibility that a non-uniform air density region
91
wherein the refraction index of the air in the projection light flux
89
varies locally may be produced in the portion into which the exhaust hot wind
90
advances and a schlieren
92
by which such picture quality deterioration as fluctuation or distortion of an image projected to the projection plane
88
through within the non-uniform air density region
91
occurs with the image may possibly occur.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a projection type display apparatus wherein heat generated from a plurality of heat sources in the inside of an outer housing can be exhausted efficiently and the weight of the outer housing can be balanced readily in the leftward and rightward direction.
It is another object of the present invention to provide a projection type display apparatus wherein a projection lens and an exhaust port for an internal heat source are disposed on a front wall of an outer housing to assure a good convenience of
Ohishi Mineo
Okamoto Koji
Adams Russell
Maioli Jay H.
Sever Andrew
Sony Corporation
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