Optics: image projectors – Temperature control
Reexamination Certificate
2001-03-07
2003-09-23
Adams, Russell (Department: 2851)
Optics: image projectors
Temperature control
C353S020000, C353S058000, C353S060000, C353S061000
Reexamination Certificate
active
06623125
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat-dissipating device, and more particularly to a heat-dissipating device for being used in a liquid crystal display projector.
BACKGROUND OF THE INVENTION
Please refer to FIG.
1
.
FIG. 1
is a schematic view showing the components of a liquid crystal display projector (LCD projector). Three liquid crystal displays are comprised in the LCD projector for respectively presenting red, blue and green colors to project image. A polychromatic light from a light source
1
passes through a light integrator
3
to provide a parallel beam to a condensing lens
4
. The beam condensed from the condensing lens
4
is separated into blue, green and red light by a first dichroic mirror
5
and a second dichroic mirror
6
. The red light is reflected by a first reflecting mirror
17
to a relay lens
21
. The red light passed from the delay lens
21
passes through a second reflecting mirror
18
to a red-light modulating LCD
7
.
The blue light is reflected to a lens
15
by a third reflecting lens
14
. The blue light is modulated as a parallel beam by the lens
15
. The blue light passed from the lens
15
is projected to a blue-light modulating LCD
9
. The green light is modulated as a parallel beam by a lens
16
. The green light passed from the lens
16
is projected onto a green-light modulating LCD
8
.
In addition, a first polarizer
170
, a second polarizer
160
and a third polarizer
150
are disposed adjacent to the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
, respectively. The polarizers are used for polarizing each of the red, green and blue light as a P-polarized light or an S-polarized light.
The red light comes into the red-light modulating LCD
7
through the first polarizer
170
. The green light comes into the green-light modulating LCD
8
through the second polarizer
160
. The blue light comes into the blue-light modulating LCD
9
through the third polarizer
150
.
The red, green and blue light respectively modulated by the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
is synthesized by a trichroic prism
10
. The beam synthesized by the trichroic prism is projected onto a screen by a projection lens
11
.
When the incident light is transmitted through the polarizers, the temperatures of the first polarizer
170
, the second polarizer
160
and the third polarizer
150
are increased due to the S-polarized or P-polarized light. Furthermore, the temperatures of the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
are also increased due to the S-polarized or P-polarized light.
However, the energy of different monochromic light is different. The formula of a monochromic light energy is e=h×&ngr;, wherein h=6.626176×10
−34
joule/sec and &ngr; is the frequency of the monochromic light. Hence, because the energy absorbed by each modulating LCD is different, the temperatures of the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
are different.
Generally, the limiting operation temperature of the LCD is about 60° C. and the limiting operation temperature of the polarizer is about 80° C. In addition, the difference between the temperatures of the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
would decrease the quality of the projected image and even cause failure of the LCD.
Please refer to FIG.
2
.
FIG. 2
is a schematic view showing a liquid crystal display projector having a heat-dissipating device according to the prior art. The heat generated from a the red-light modulating LCD
7
, a green-light modulating LCD
8
and a blue-light modulating LCD
9
is dissipated by a fan
11
. The fan
11
is an axial fan disposed under a prism
10
, the red-light modulating LCD
7
, the green-light modulating LCD
8
and the blue-light modulating LCD
9
.
TABLE 1
Type of fan
a
b
c
Axial fan
39° C.
49° C.
52° C.
Blast blower
38.5° C.
45.7° C.
48° C.
a: red-light modulating LCD
b: green-light modulating LCD
c: blue-light modulating LCD
Please refer to Table 1. The temperature of each LCD comprised in the LCD projectors having different type of fans is measured and shown in Table 1. The airflow is blown straightly from the axial fan disposed under the red-light modulating LCD, the green-light modulating LCD and the blue-light modulating LCD, and leads to great difference between the temperatures of the LCDs. Thus, the color of the projected image is diverged from normal, and the quality of the projected image is decreased.
Please refer to FIG.
3
and Table 1. The heat generated from a LCD
7
, a LCD
8
, a LCD
9
and polarizers
10
is dissipated by a blast blower
80
through a channel
82
. The channel
82
is in rectangular shape. When the blast blower
80
is activated, the heat generated from the LCD
7
, the LCD
8
, the LCD
9
and polarizers
10
is dissipated by the airflow through the channel
82
. However, the temperatures of the LCD
7
, the LCD
8
and the LCD
9
are not uniform. Furthermore, the difference between the temperatures of the LCD
7
, the LCD
8
and the LCD
9
is greater than 5° C. Hence, the manner of using a blast blower sidewardly connected with a rectangular-shaped channel to dissipate the heat should be improved.
In order to overcome the foresaid problems, the present invention provide a heat-dissipating device for a LCD projector.
SUMMARY OF THE INVENTION
It is an object of the present to provide a heat-dissipating device for being used in a liquid crystal display projector having liquid crystal displays and polarizers.
In accordance with the present invention, the heat-dissipating device includes a heat-dissipating channel and a fan.
The heat-dissipating channel is disposed under the liquid crystal displays and the polarizers and includes a main path, a first branch, a second branch, and a plurality of vents corresponding to and adjacent to the liquid crystal displays and the polarizers, respectively.
The fan is connected with an end of the heat-dissipating channel
When an airflow is blown from the fan into the main path, the first branch and the second branch and discharged outwardly through the vents, heat generated from the liquid crystal displays and the polarizers is dissipated and temperatures around the liquid crystal displays are kept near isothermal.
Preferably, the first branch and the second branch are bilaterally connected with the main path. The heat-dissipating channel is about Y-shaped.
In addition, the heat-dissipating device further includes a first regulation plate disposed at a first entrance of the first branch for regulating a first width of the first entrance to limit relative spaces of the first branch, the second branch and the main path.
Furthermore, the heat-dissipating device includes a second regulation plate disposed at a second entrance of the second branch for regulating a second width of the second entrance to limit relative spaces of the first branch, the second branch and the main path.
Preferably, the number of the liquid crystal displays is three and the number of the plurality of vents is three.
Preferably, two vents and two liquid crystal displays are positioned on the first branch, and the other vent and the other liquid crystal display are positioned on the second branch.
Preferably, two vents and two liquid crystal displays are positioned on the second branch, and the other vent and the other liquid crystal display are positioned on the first branch.
Preferably, the fan is a blast blower and sidewardly connected with the heat-dissipating device. The liquid crystal displays are arranged in V-shape.
It is another object of the present invention to provide a liquid crystal display projector.
In accordance with the present invention, the liquid crystal display projector includes three polarizers, three liq
Chen Hsi-Chao
Haven Tom
Adams Russell
Cruz Magda
Delta Electronics , Inc.
Mathews, Collins Shepherd & McKay, P.A.
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