Optics: image projectors – Temperature control – Blower
Reexamination Certificate
2002-08-27
2004-01-06
Adams, Russell (Department: 2851)
Optics: image projectors
Temperature control
Blower
C353S060000, C353S057000
Reexamination Certificate
active
06672723
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a liquid crystal projector which includes an optical prism unit in which a liquid crystal panel which modulates light in response to a video signal is used.
A liquid crystal projector is known which uses a liquid crystal panel which modulates light in response to a video signal in order to obtain a project image screen of a large size. A conventional liquid crystal projector includes, as principal components thereof, a light source lamp unit, an irradiation optical unit for spectrally separating white light from the light source into light components of red, blue and green and condensing the spectrally separated color light components, an optical prism unit including liquid crystal panels for modulating the condensed light components in response to image information and a dichroic prism for color synthesizing the modulated light components, a projection optical unit for projecting the color synthesized light in an enlarged scale, and a circuit unit including a power supply circuit, a signal processing circuit and so forth.
In recent years, in a liquid crystal projector, a high resolution liquid crystal panel is used in order to project image information as a more distinct picture, and increase in brightness is promoted in order to make the projection screen brighter. A liquid crystal projector of the type described incorporates cooling apparatus for individually cooling the light source lamp unit, circuit unit and liquid crystal panel unit which act as internal heat generating sources. Usually, the cooling apparatus include a cooling fan disposed therein suitably for their application in such a manner as to suck air outside a cabinet into the inside of the cabinet and blast the air to the pertaining unit or units.
FIGS. 5A and 5B
show a general configuration of a conventional optical prism unit, and wherein
FIG. 5A
is a plan view and
FIG. 5B
is a sectional view taken along line B—B of FIG.
5
A.
Referring to
FIGS. 5A and 5B
, the optical prism unit
50
shown includes an upper plate
51
and a lower plate
52
, a dichroic prism
53
held between the upper plate
51
and the lower plate
52
, and three liquid crystal panel units
54
,
55
and
56
secured to three different faces of the dichroic prism
53
into which light is introduced. A cooling fan
57
for cooling the optical prism unit
50
is disposed below the lower plate
52
. The upper plate
51
and the lower plate
52
are rectangular parallelepipeds and are held in contact with the top and bottom faces of the dichroic prism
53
to held the dichroic prism
53
therebetween.
Air holes
59
for introducing air current from the cooling fan
57
therethrough are formed in a base
58
for the lower plate
52
. The air holes
59
are disposed below the liquid crystal panel units
54
,
55
and
56
so that air may be brought into direct contact with the liquid crystal panel units
54
,
55
and
56
. Thus, blast air from the cooling fan
57
passes through the air holes
59
and is brought into direct contact with the liquid crystal panel units
54
,
55
and
56
to cool the liquid crystal panel units
54
,
55
and
56
. The bottom face of the lower plate
52
contacts over the entire area thereof with the base
58
having the configuration just described so that the dichroic prism
53
and so forth are held stably on the base
58
.
In recent years, it is demanded to reduce the size of a liquid crystal projector so that it can be carried conveniently. However, since reduction of the size decreases a heat radiating space, the cooling efficiency is deteriorated. Further, as the brightness is increased, the liquid crystal panel generates an increased amount of heat. Therefore, it is a subject to cool the liquid crystal panel units and other units to temperatures lower than their heat-resistant temperatures. In other words, it is a subject to raise the cooling efficiency together with increase of the brightness and reduction of the size.
In the optical prism unit
50
shown in
FIGS. 5A and 5B
, since the size of the air holes
59
is restricted by the arrangement of the lower plate
52
and the optical units including condensing lenses and mirrors, it is difficult to increase the cooling air amount to the liquid crystal panel units
54
,
55
and
56
without increasing the size of the optical prism unit
50
. In other words, with the conventional structure, it is difficult to increase the cooling air amount and lower the temperatures in operation of the liquid crystal panels and so forth while reduction of the size is achieved.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a liquid crystal projector which can blast an increased amount of cooling air to raise the cooling efficiency without increasing the size of an optical prism unit.
In order to attain the object described above, according to an aspect of the present invention, there is provided a liquid crystal projector including a dichroic prism, a base for securing the dichroic prism with a plate interposed therebetween, a liquid crystal panel unit disposed on a side face of the dichroic prism, and a cooling fan disposed below the base, the base having an air hole formed therein such that air current generated by the cooling fan is introduced to the liquid crystal panel unit through the air hole to cool the liquid crystal panel unit, a portion of the plate which opposes to the air hole of the base being formed so as to have an inclined face, a curved face or a cutaway portion.
With the liquid crystal projector, the sectional area of the flow path for the air current generated by the cooling fan can be increased by the inclined face, curved face or cutaway portion formed on the plate. Consequently, an increased amount of cooling air can be introduced to the liquid crystal panel unit to cool the liquid crystal panel unit efficiently. More particularly, since the portion of the plate which opposes to the air hole of the base is formed so as to have an inclined face, a curved face or a cutaway portion, it can introduce an increased amount of cooling air to the liquid crystal panel unit to cool the liquid crystal panel unit efficiently. Consequently, the amount of cooling air can be increased to raise the cooling efficiency to lower the temperature in operation of the liquid crystal panel unit without increasing the speed of rotation or the size of the cooling fan. Further, where the cooling efficiency is raised, the speed of rotation or the size of the cooling fan can be reduced, and therefore, a cooling fan of a reduced size can be used to augment the quietness of the liquid crystal projector. Further, since the temperature in operation of the liquid crystal panel unit can be kept low, the life and the reliability of the liquid crystal panel unit are augmented.
According to another aspect of the present invention, there is provided a liquid crystal projector including a dichroic prism, a base for securing the dichroic prism with a plate interposed therebetween, a plurality of liquid crystal panel units disposed on side faces of the dichroic prism, a cooling fan disposed below the base, the base having air holes formed therein such that air current generated by the cooling fan is introduced to the liquid crystal panel units through the air holes to cool the liquid crystal panel units, and air current guiding means provided between the cooling fan and the base for introducing the air current to a particular one of the side faces of the dichroic prism on which a particular one of the liquid crystal panel units is disposed.
With the liquid crystal projector, since the air current guiding means is provided between the cooling fan and the base for introducing the air current to the particular side face of the dichroic prism on which the particular liquid crystal panel unit is disposed, air current generated by the cooling fan can be introduced in a concentrated manner to the particular liquid crystal panel unit which exhibits a comparatively high temperature in operation. Consequently,
Akaike Yoshifumi
Sugimoto Hideki
Watanabe Shinya
Adams Russell
Dalakis Michael
Depke Robert J.
Holland & Knight LLC
LandOfFree
Liquid crystal projector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal projector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal projector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3202451