Title: Projector device
Abstract: A projector device adapted to project an image-forming beam using a lamp as a light source. The lamp is installed within a rectangular parallelepipedal housing, and an exhaust fan is disposed to the rear of the lamp. The top wall of the housing surrounding the lamp is given an opening pattern asymmetric about the optical axis of the lamp by forming an air inlet opening in a position deviated from the optical axis is toward a direction orthogonal to the axis for producing a swirling air current within the housing by operating the exhaust fan. The lamp can be effectively cooled with reduced quantities of air.
Patent Number: 6,913,361 Issued on 07/05/2005 to Gishi, et al.
| Inventors:
|
Gishi; Hiromitsu (Higashiosaka, JP);
Hamada; Fumihiko (Kobe, JP);
Okazaki; Shoji (Higashiosaka, JP);
Adachi; Takaharu (Daito, JP);
Yoshimura; Taichi (Higashiosaka, JP);
Uchiyama; Naoyuki (Gunma, JP);
Masuda; Mitsuhiro (Osaka, JP);
Kurokawa; Michihiro (Hirakata, JP)
|
| Assignee:
|
Sanyo Electric Co., Ltd. (Moruguchi, JP)
|
| Appl. No.:
|
995185 |
| Filed:
|
November 24, 2004 |
Foreign Application Priority Data
| Jun 21, 2001[JP] | 2001-187854 |
| Jun 21, 2001[JP] | 2001-187855 |
| Jun 21, 2001[JP] | 2001-187856 |
| Jun 21, 2001[JP] | 2001-187857 |
| Jun 21, 2001[JP] | 2001-187858 |
| Current U.S. Class: |
353/58; 353/60; 353/61; 353/119 |
| Intern'l Class: |
G03B 021/14; G03B021/16; G03B021/18; G03B021/22; G03B021/26 |
| Field of Search: |
353/20,31,52,57,58,60,61,119
349/5
|
References Cited [Referenced By]
U.S. Patent Documents
| 6280036 | Aug., 2001 | Suzuki.
| |
| 6398366 | Jun., 2002 | Hara et al.
| |
| 6494581 | Dec., 2002 | Shimizu.
| |
| 6736513 | May., 2004 | Koyama et al.
| |
| 2003/0071977 | Apr., 2003 | Miyamoto et al.
| |
| Foreign Patent Documents |
| 6-14485 | Feb., 1994 | JP.
| |
| 8-22075 | Jan., 1996 | JP.
| |
| 8-114857 | May., 1996 | JP.
| |
| 10-186517 | Jul., 1998 | JP.
| |
| 10-254061 | Sep., 1998 | JP.
| |
| 10-325982 | Dec., 1998 | JP.
| |
| 11-195402 | Jul., 1999 | JP.
| |
| 2000/-194071 | Jul., 2000 | JP.
| |
| 2000/-231154 | Aug., 2000 | JP.
| |
| 2001-13589 | Jan., 2001 | JP.
| |
| 2001-76505 | Mar., 2001 | JP.
| |
| 2001/-132694 | May., 2001 | JP.
| |
| 2001/-133885 | May., 2001 | JP.
| |
| 2001/-183746 | Jul., 2001 | JP.
| |
| 2002/-341448 | Nov., 2002 | JP.
| |
Primary Examiner: Nguyen; Judy
Assistant Examiner: Koval; Melissa J.
Attorney, Agent or Firm: Armstrong, Kratz, Quintos, Hanson & Brooks, LLP
Parent Case Text
This application is a Divisional application of U.S. patent application Ser.
No.10/473,146, filed Oct. 8, 2003, now U.S. Pat. No. 6,837,583 which is a U.S.
National Stage application of PCT/JP02/06203, filed Jun. 21, 2002.
Claims
1. A projector device housed in a casing, comprising:
an optical unit for receiving light from a light source and producing an image-forming
beam;
a lamp unit comprising the light source of the optical unit and cooling means
for cooling the light source; and
a cooling unit for cooling the optical unit, housed in a housing and disposed
independently from the cooling means of the lamp unit, the projector device projecting
the image-forming beam forward from the optical unit,
wherein the housing of the cooling unit has at least one intake in communication
with an air inlet hole formed in the casing for drawing in air from outside, at
least one air discharge opening for forcing out air toward the optical unit, and
an air channel partitioned from the inside space of the casing and extending from
the intake to the air discharge opening, a plurality of cooling fans being provided
in the air channel so that only the air drawn in through the air inlet hole and
the intake from outside the casing is forced out of the air discharge opening against
the optical unit to thereby cool the optical unit.
Description
BACKGROUND OF THE ENVENTION
1. Field of the Invention
The present invention relates to projector devices, such as liquid crystal projectors,
for projecting an image-forming beam on a screen using a lamp as a light source.
2. Description of Related Art
Projector devices of the type mentioned comprise as arranged in a casing
a lamp unit, and an optical system including a polarization beam splitter, polarizing
plates, liquid crystal panels, a projection lens, etc. The lamp unit has a mercury
lamp disposed within a housing and an exhaust fan disposed to the rear of the mercury
lamp. Air streams are produced around the mercury lamp by operating the exhaust
fan for cooling the lamp.
However, with high-luminance projector devices wherein a superhigh-pressure
mercury lamp is used as the light source, the mercury lamp generates a large quantity
of heat and therefore requires high-speed rotation of the exhaust fan to produce
air streams at a high speed and fully cool the lamp. This entails the problem that
the exhaust fan makes a great noise.
An object of the present invention is to provide a projector device wherein the
light-source lamp can be effectively cooled with reduced quantities of air streams.
SUMMARY OF THE INVENTION
The present invention provides a projector device wherein a lamp unit 4
comprises a lamp 5 disposed within a rectangular parallelepipedal housing
41 and an exhaust fan 40 disposed to the rear of the lamp 5.
At least one of four peripheral walls of the housing 41 surrounding the
lamp 5 is given an opening pattern asymmetric about the optical axis of
the lamp 5 by forming at least one air inlet opening in a position deviated
from the optical axis toward a direction orthogonal to the axis.
With the projector device of the invention described, the air drawn into the
housing 41 through the air inlet opening from outside the housing 41
flows toward a direction deviated from the optical axis of the lamp 5, producing
a swirling current within the housing 41. This effects enhanced heat transfer
between the outer peripheral surface of the lamp 5 and the swirling current
to effectively cool the lamp 5 with the air.
stated specifically, the exhaust fan 40 is an axial-flow fan. This
produces an air current revolving around the lamp 5 inside the housing 41.
When the above-mentioned at least one air inlet opening is positioned as deviated
from the optical axis toward a direction along the direction of rotation of the
exhaust fan 40, the direction of swirling air as drawn into the housing
41 from outside matches the direction of a swirling force given to the air
current by the rotation of the exhaust fan 40 to assist in the flow of swirling
air around the lamp 5.
Further stated more specifically, a cooling unit 6 is disposed along
an optical system of the device, and the cooling unit 6 has one or a plurality
of intake windows for drawing in outside air, one or a plurality of cooling fans
for drawing in outside air through the intake window or windows and discharging
the air, a plurality of air discharge ports facing toward respective high-temperature
portions of the optical system, and a channel network 8 for guiding the
air discharged from the cooling fan or fans to the air discharge ports, the channel
network 8 comprising a plurality of channels for distributing the air to
be forced out of the air discharge ports toward the respective high-temperature
portions of the optical system in quantities in accordance with the temperature
of the high-temperature portions.
The cooling unit 6 has a air discharge ports facing toward the high-temperature
portions of the optical system, and a channel network 8 comprising a plurality
of channels extending from the discharge opening or openings of one or the plurality
of cooling fans to the respective air discharge ports, so that, due to the operation
of the cooling fan, the outside air drawn in through the intake window or windows
is forced out from the respective air discharge ports directly against the high-temperature
portions of the optical system to concentrically cool these portions of the system.
Since the channels of the channel network 8 are adjusted, for example, in
cross sectional area thereof so as to distribute the air to be forced out of the
air discharge ports toward the respective high-temperature portions of the optical
system in quantities in accordance with the temperature of the high-temperature
portions, the high-temperature portions are cooled to a substantially uniform temperature.
This ensures sufficient cooling with smaller quantities of air than the prior art
wherein air is merely caused to flow within the casing for cooling the entire optical system.
Further stated more specifically, the casing 1 has at least one intake
for drawing in air from outside, at least one air discharge opening for forcing
out air toward the optical system, and an air channel partitioned from the inside
space of the casing and extending from the intake to the air discharge opening,
a cooling fan being provided in the air channel so that only the air drawn in through
the intake from outside the casing is forced out of the air discharge opening against
the optical system to thereby cool the optical system.
With this specific construction, the intake faces toward the outside of the
casing, and the air channel extending from the intake to the air discharge opening
is partitioned from the casing inside space (wherein the optical system is installed),
so that the operation of the cooling fan draws in air of low temperature from outside
the casing through the intake, forcing the air of low temperature drawn in against
the optical system without permitting the air to be mixed with the air of high
temperature inside the casing. The optical system is therefore fully cooled.
Further stated more specifically, the lamp 5 of the lamp unit 4
comprises a reflector 51, a light-producing portion 50 disposed at
the focal position of the reflector 51 or in the vicinity thereof, and a
light-transmitting plate 53 covering a front opening of the reflector 51,
the lamp unit 4 having an air intake 52 for guiding air from outside
the lamp 5 toward the light-producing portion 50 and an air outlet
54 for leading out the air guided in through the air intake 52 to
the outside of the lamp 5, a blower fan 44 being connected to the
air intake 52 by a duct 47 to forcibly cool the light-producing portion
50 with air by operating the blower fan 44. With this specific construction,
the operation of the blower fan 44 forces air directly against the light-producing
portion 50 of the lamp 5 which portion has the highest temperature,
whereby the portion 50 is forcibly cooled. Since the reflecting surface
of the reflector 51 surrounding the light-producing portion 50 is
an inwardly curved surface, an air stream flowing along the inwardly curve surfaces,
i.e., an air stream swirling around the light-producing portion 50, is created,
giving an increased coefficient of heat transfer to the surface of the light-producing
portion 50. This ensures effective cooling with a smaller quantity of air
than the prior art wherein an air stream is produced around the reflector.
Further stated more specifically, the air channel extending from the intake
of the casing 1 to the air discharge opening thereof has installed therein
as the cooling fan a sirocco fan of one-side suction type having an intake opening
in only one side thereof, with above-mentioned one side positioned at the greatest
possible distance away from, and opposed to, a wall of the air channel, and a space
provided between above-mentioned one side and the air channel wall is in communication
with the intake.
The sirocco fan of one-side suction type used as the cooling fan in this arrangement
can be smaller in thickness than sirocco fans of two-side suction type. As a result,
the side of the fan provided with an intake opening can be a sufficient distance
away from the air channel wall to which the intake side is opposed, providing a
large space between the intake side and the air channel wall. Accordingly, the
channel extending from the intake to the air discharge opening of the sirocco fan
via the space can be given a sufficiently large cross sectional area, which greatly
reduces the flow resistance (pressure loss) to be offered to the air flowing through
this channel. As a result, a sufficient quantity of air is available even if the
sirocco fan has a low output, hence a reduced noise.
Thus, with the projector device of the present invention, more efficient heat
transfer is ensured between the outer peripheral surface of the lamp 5 of
the lamp unit 4 and the swirling air current to effectively cool the lamp
5 with the air.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a liquid crystal projector according to the invention.
FIG. 2 is a diagram showing the constructions of a lamp unit and an optical
system which are included in the liquid crystal projector.
FIG. 3 is an exploded perspective view of the liquid crystal projector.
FIG. 4 is a perspective view showing the liquid crystal projector, with the
lamp unit, the optical unit and a cooling unit removed from a lower half case.
FIG. 5 is a perspective view showing the liquid crystal projector, with the
lamp unit, the optical unit and the cooling unit arranged into an assembly as housed
in the lower half case.
FIG. 6 is a plan view of the lamp unit.
FIG. 7 is a view in section of the lamp unit.
FIG. 8 is a perspective view partly broken away and showing a lamp unit having
an opening pattern which is asymmetric about a longitudinal center line.
FIG. 9 is a perspective view partly broken away and showing a lamp unit having
an opening pattern which is symmetric about a longitudinal center line.
FIG. 10(
a), FIG. 10(
b) and FIG. 10(
c)
are plan views of three kinds of lamp units which are different in opening pattern.
FIG. 11 is a perspective view of the cooling unit and a color composition device.
FIG. 12 is a perspective view of the cooling unit.
FIG. 13 is a plan view of the cooling unit.
FIG. 14 is an exploded perspective view of the cooling unit.
FIG. 15 is a plan view of the body of a housing for the cooling unit.
FIG. 16 is a plan view showing the relationship in position between the cooling
unit and three polarization-liquid crystal assemblies of the optical unit.
FIG. 17 is a view in section of a second cooling fan of the cooling unit.
FIG. 18 is a view in section of a third cooling fan of the cooling unit.
BEST MODE OF CARRYING OUT THE INVENTION
With reference to the drawings, a detailed description will be given below of
the present invention as embodied into a liquid-crystal projector.
Overall Construction
The present invention provides a liquid crystal projector, which has a flat casing
1 comprising a lower half case
11 and an upper half case
12
as shown in FIG.
1. The casing
1 has a front panel
13 provided
with a projection window
14 and vents
15 for the hot air discharged
from a lamp unit
4 housed in the casing.
As shown in FIGS. 3 to
5, arranged inside the casing
1 are an optical
unit
2 for producing a color image-forming beam, the lamp unit
4
serving as a light source for the optical unit
2, and a cooling unit
6
for cooling the optical unit
2.
Optical Unit
2
With reference to FIG. 2, the optical unit
2 guides white light from
the lamp unit
4 to a two-color separating mirror
25 for blue by way
of a first integrator
21, first mirror
22, second integrator
23
and polarization beam splitter
24 to thereby separate off blue light. The
light passing through the two-color separating mirror
25 for blue is guided
to a two-color separating mirror
27 for green to thereby separate off green light.
The blue light separated off by the separating mirror
25 for blue impinges
on a color composition device
3 via a second mirror
26. The green
light separated off by the separating mirror
27 for green is incident on
the color composition device
3, and red light is incident on the color composition
device
3 via a third mirror
28.
The blue light incident on the color composition device
3 is led through
an incidence polarizing plate
31 for blue, liquid crystal panel
32
for blue and emergence polarizing plate
33 for blue of the device
3
to a color composition prism
30. The green light incident on the color composition
device
3 is led through an incidence polarizing plate
34 for green,
liquid crystal panel
35 for green and emergence polarizing plate
36
for green of the device
3 to the color composition prism
30. The
red light incident on the color composition device
3 is led through an incidence
polarizing plate
37 for red, liquid crystal panel
38 for red and
emergence polarizing plate
39 for red of the device
3 to the color
composition prism
30.
The image-forming beams of three colors led to the color composition prism
30
are combined by the prism, and the resulting color image-forming beam is led through
a projection lens
20 and projected on a screen in the front upon enlargement.
Lamp Unit
4
As shown in FIG. 7, the lamp unit
4 comprises a superhigh-pressure mercury
lamp
5 provided within a housing
41. An exhaust fan
40 is
disposed to the rear of the lamp
5.
The mercury lamp
5 comprises a reflector
51, a light-producing
portion
50 at the focal position of the reflector
51, and a light-transmitting
plate
53 covering an opening of the reflector
51. Provided between
the lower end of the reflector
51 and the opening edge of the reflector
51 is a long narrow air intake
52 extending widthwise of the plate
53. Formed between the upper end of the plate
53 and the opening
edge of the reflector
51 is a long narrow air outlet
54 extending
widthwise of the plate
53. The air intake
52 and outlet
54
each have an opening shaped to slant toward the light-producing portion
50.
With reference to FIG. 6, a top wall of the housing
41 has one long narrow
first inlet opening
45 extending in the longitudinal (forward or rearward)
direction of the housing and positioned at one end of the wall in the widthwise
direction orthogonal to the optical axis (in the longitudinal direction) of the
lamp. The housing upper wall also has a plurality of long narrow second air inlet
openings
46 extending longitudinally of the housing, and further has a third
air inlet opening
49 positioned at one end thereof toward the light emergent
direction and extending widthwise of the housing.
A fan case
42 is connected by a duct
47 to the housing
41
at a portion thereof opposed to the air intake
52. A blower fan
44
is housed in the fan case
42 and has an air outlet
48 facing toward
the interior of the duct
47 and an air inlet
43 facing downward.
The air inlet
43 is in communication with a plurality of air inlet holes
16 formed in the bottom wall of the lower half case
11 as shown in
FIG.
4.
When the power source for the liquid crystal projector is turned on, the exhaust
fan
40 and the blower fan
44 start to rotate. The rotation of the
exhaust fan
40 draws air in through the first, second and third air inlet
openings
45,
46,
49 of the housing
41, producing an
air current flowing around the lamp
5 toward the exhaust fan
40 to
cool the outer peripheral surface of the lamp
5 with the air current. The
top wall of the housing
41 has an opening pattern which is made asymmetric
about the longitudinal center line of the housing by the presence of the first
air inlet opening
45, so that formed around the reflector
51 of the
lamp
5 is an air current flowing toward the exhaust fan
40 while
rotating about the optical axis of the lamp
5 in one direction.
For example, in the case where the exhaust fan
40 rotates clockwise as
shown in FIG. 8, the top wall of a housing
41b is given an opening
pattern which is asymmetric in its entirety about the optical axis of the lamp
S by forming a first air inlet opening
45 and a third air inlet opening
49 as positioned generally closer to the right side. This produces an air
current rotating clockwise around the lamp
5 and flowing through the exhaust
fan
40 while remaining rotating.
Consequently, uniform heat transfer takes place over the entire outer
peripheral surface of the lamp
5 to fully cool the lamp
5 with a
smaller quantity of air current.
On the other hand, in the case where the top wall of a housing
41a
has
a plurality of second air inlet openings
46 which are symmetric about the
optical axis of the lamp as shown in FIG. 9, little or no air current is produced
which rotates around the lamp
5, but a deviated air current occurs partly
around the outer peripheral surface of the lamp
5. This results in insufficient
heat transfer over the outer peripheral surface of the lamp
5 to entail
an uneven temperature distribution.
FIG.
10(
a) shows a housing 41a having a plurality of second air
inlet openings
46 formed in its top wall centrally thereof. FIG.
10(
b)
shows a housing 41b having a third air inlet opening
49 extending in an
end portion of its top wall widthwise thereof and a first air inlet opening
45
extending in a side portion of the top wall longitudinally thereof. FIG.
10(
c)
shows a housing
41c having all of these first air inlet opening
45,
second air inlet openings
46 and third air inlet opening
49. Table
1 shows the distributions of temperatures over the lamp outer peripheral surface
as measured for the three kinds of lamp units having these housings
41a,
41b,
41c, respectively.
| |
TABLE 1 |
| |
|
| |
Housing (41a) |
Housing (41b) |
Housing (41c) |
| Fan voltage (V) |
6 |
8 |
10 |
6 |
8 |
10 |
6 |
8 |
10 |
| |
| Top of lamp (° C.) |
253 |
215 |
189 |
265 |
231 |
205 |
260 |
221 |
196 |
| Bottom of lamp (° C.) |
276 |
246 |
222 |
274 |
237 |
213 |
270 |
241 |
219 |
| Left side of lamp (° C.) |
265 |
233 |
208 |
268 |
227 |
200 |
279 |
237 |
211 |
| Right side of lamp (° C.) |
270 |
234 |
210 |
250 |
216 |
193 |
271 |
232 |
206 |
| Average temp. (° C.) |
266 |
232 |
207 |
264 |
228 |
203 |
270 |
233 |
208 |
| Max. temp. (° C.) |
276 |
246 |
222 |
274 |
237 |
213 |
279 |
241 |
219 |
| Temp. difference (° C.) |
23 |
31 |
33 |
24 |
21 |
20 |
19 |
20 |
23 |
| |
The results given in Table 1 reveal that the housing
41b or
41c
having an opening pattern which is asymmetric in its entirety about the lamp
optical axis is lower in maximum temperature and smaller in the difference between
the maximum temperature and the minimum temperature than the housing
41a
having an opening pattern which is symmetric about the optical axis.
With the lamp unit
4 shown in FIGS. 6 and 7, air is drawn into the air
inlet
43 of the blower fan
44 through the air inlet holes
16
of the lower half case
11 and is discharged from the air outlet
48
by the rotation of the blower fan
44. The discharged air is led through
the duct
47 into the reflector
51 via the air intake
52 of
the lamp
5. Since the air intake
52 faces the light-producing portion
50, the air led into the reflector
51 is forced directly against
this portion
50. The air flowing along an inwardly curved surface of the
reflector
51 further produces a swirling current surrounding the light-producing
portion
50.
Consequently, the air led into the reflector
51 undergoes heat
exchange with the light-producing portion
50 with high thermal conductivity,
forcibly cooling the portion
50, and is thereafter guided through the air
outlet
54 to the outside of the reflector
51.
The air guided to the outside of the reflector
51 via the air outlet
54
joins the air current flowing around the reflector
51 and flows toward the
exhaust fan
40. The air currents passing through the fan
40 are discharged
forward from the vents
15 of the front panel
13 shown in FIG.
1.
Since the light-producing portion
50 which is the highest of all the
other portions of the lamp
5 in temperature is cooled efficient as described
above, so that the exhaust fan
40 and the blower fan
44 can be smaller
in the quantity of air current to be produced. This serves to greatly reduce the
noise to be produced by the fans
40,
44.
The liquid crystal projector of the present invention comprises an optical system
wherein the direction of emergence of white light from the lamp unit
4 and
the direction of projection of an image-forming beam from the optical unit
2
are 180 degrees different from each other, with the result that the front panel
13 of the casing
1 has both the projection window
14 and the
vents
15. The noise produced by the fans incorporated in the lamp unit
4
is therefore released toward the screen along the direction of projection of the
beam. This reduces the likelihood that the noise from the fans will reach the viewers
as positioned a greater distance rearwardly away from the screen than the projector.
Cooling Unit
6
As shown in FIGS. 3 and 4, the cooling unit
6 is disposed under the optical
unit
2 for cooling the optical unit
2. The cooling unit
6
has a flat housing
60 as shown in FIGS. 11 and 12 and is adapted to discharge
air toward four heat generating portions of the optical unit
2 above the
unit
6 from four air discharge ports
63,
64,
65,
69
provided in the surface of the housing
60.
Of the four ports
63,
64,
65,
69, the three ports
63,
64,
65 shown in FIG. 16 are respectively an air discharge
port for blue which is open toward the incidence polarizing plate
31 for
blue, liquid crystal panel
32 for blue and emergence polarizing plate
33
for blue of the color composition device
3; an air discharge port for green
which is open toward the incidence polarizing plate
34 for green, liquid
crystal panel
35 for green and emergence polarizing plate
36 for
green of the device
3; and an air discharge port for red which is open toward
the incidence polarizing plate
37 for red, liquid crystal panel
38
for red and emergence polarizing plate
39 for red of the device
3.
The remaining port
69 shown in FIG. 12 is an air discharge port which
is open toward the polarization beam splitter (hereinafter referred to as "PBS")
24 and serves for the PBS.
With reference to FIG. 14, the housing
60 of the cooling unit
6
comprises a body
61 and a lid
62, and the four air discharge ports
63,
64,
65,
69 are formed in the lid
62. The
housing body
61 is provided with first to third three cooling fans
66,
67,
68 arranged in a row. The air discharged from these cooling fans
66,
67,
68 is passed through a channel network
8 provided
by a plurality of partition walls and made into divided flows or confluent flows
to give four streams of suitable flow rates as will be described below. These streams
are forced out of the four air discharge ports
64,
64,
65,
69.
Of the incidence polarizing plates, liquid crystal panels and emergence polarizing
plates for the respective colors of the color composition device
3 (the
three components of the device
3 for each color will hereinafter be referred
to as the "polarization-liquid crystal assembly"), the polarization-liquid crystal
assembly for blue is greatest in the quantity of heat generation, so that the air
discharged from each of the cooling fans
66,
67,
68 is divided
in two streams, and one of the streams is assigned to the polarization-liquid crystal
assembly for green, like assembly for red and PBS for cooling these components,
and the other air stream is entirely assigned to the polarization-liquid crystal
assembly for blue.
With reference to FIGS. 14 and 15, provided as the channel network
8
are a channel extending from the first cooling fan
66 to the air discharge
port
63 for blue and the air discharge port
69 for PBS, a channel
from the second cooling fan
67 to the air discharge port
63 for blue
and the air discharge port
64 for green, and a channel from the third cooling
fan
68 to the air discharge port
63 for blue and the air discharge
port
65 for red. The air discharge port
69 for PBS is provided with
a guide blade
89 for forcing the air stream from the first cooling fan
66
against a high-temperature portion of the PBS
24, i.e., against the central
portion of the light emergent surface thereof, at a high speed.
For cooling each of the polarization-liquid crystal assemblies for blue, green
and red, the quantity and direction of air stream for the incident side and the
emergent side are suitably adjusted by providing air stream guide faces as will
be described below.
Stated more specifically with reference to FIG. 13, the air discharge port
63 for blue is provided with first to fourth partition walls
81,
82,
83,
84 to form a first air discharge portion
91
for discharging an air stream from the first cooling fan
66, a second air
discharge portion
92 for discharging an air stream from the second cooling
fan
67 and a third air discharge portion
93 for discharging an air
stream from the third cooling fan
68. Air stream guide faces (not shown)
are formed on the respective first and third partition walls
81,
83
to adjust the quantity and direction of the air stream from the second and third
cooling fans
67,
68 to the incident side and the emergent side of
the polarization-liquid crystal assembly for blue.
A guide blade
85 is installed in the air discharge port
64 for
green
for providing two air discharge portions
95,
96 on opposite sides
of the blade to adjust the quantity and direction of the air stream from the second
cooling fan
67 to the incident side and the emergent side of the polarization-liquid
crystal assembly for green. Furthermore, a fifth partition wall
86 and a
guide blade
87 are installed in the air discharge port
65 for red
to form two air discharge portions
97,
98 and adjust the quantity
and direction of the air stream from the third cooling fan
68 to the incident
side and the emergent side of the polarization-liquid crystal assembly for red.
FIG. 16 shows the relationship between the air discharge port
63 for
blue and the polarization-liquid crystal assembly for blue, the relationship between
the air discharge port
64 for green and the polarization-liquid crystal
assembly for green and the relationship between the air discharge port
65
for red and the polarization-liquid crystal assembly for red.
The air stream adjusted in quantity and direction as stated above is applied
to the incident side and the emergent side of each polarization-liquid crystal
assembly to effect efficient cooling.
The first to third cooling fans
66,
67,
68 shown in FIG.
14 are each a sirocco fan of one-side suction type having an intake opening at
one side of the casing. The first and second cooling fans
66,
67
are installed in the housing body
61 with their intake openings
66a,
67a facing upward, and have respective discharge openings
66b,
67b facing toward the inlet of the channel network
8. The
third cooling fan
68 is installed in the housing body
61 with its
intake opening
68a facing downward, and has a discharge opening
68b
facing toward the inlet of the channel network
8.
The housing body
61 has a rear wall provided with a first rear intake
window
71, second rear intake window
72 and third rear intake window
73 corresponding respectively to the first to third cooling fans
66
to
68 as shown in FIG. 14. A bottom intake window
74 corresponding
to the third cooling fan
68 is formed in the bottom wall of the housing
body
61 as seen in FIG.
18.
FIG. 17 shows the sectional construction of the cooling unit
6 at the
position where the second cooling fan
67 is installed. The unit
6
has the same sectional construction as above also at the position where the first
cooling fan
66 is installed. FIG. 18 shows the sectional construction of
the cooling unit
6 at the position where the third cooling fan
68
is installed.
The first cooling fan
66 and the second cooling fan
67 are provided
thereabove with the largest possible space S between the top wall of the lid
62
and these fans. The air drawn in through the rear intake windows
71,
72
of the housing body
61 flows through this space into the intake openings
66a,
67a of the first and second cooling fans
66,
67 as indicated by arrows in FIG.
17. Further provided under the
third cooling fan
68 between the bottom wall of the body
61 and the
fan is the largest possible space S, through which the air drawn in via the rear
intake window
73 and the bottom intake window
74 is drawn into the
intake opening
68a of the third cooling fan
68.
The three rear intake windows
71,
72,
73 of the housing
body
61 are in communication with intake ports (not shown) formed in the
rear wall of the casing
1, and the bottom intake window
74 of the
housing body
61 communicates with intake ports (not shown) formed in the
bottom wall of the casing
1.
Thus, the intake openings
66a,
67a,
68a
of the cooling fans
66,
67,
68 communicate with the outside
of the casing
1 and are held out of communication with the interior of the
casing
1 by the wall of the housing
60, so that only the air of low
temperature outside the casing
1 is drawn into the cooling fans
66
to
68 without the likelihood that the air of high temperature within the
casing
1 will be drawn in. As a result, the air of low temperature is forced
against the optical unit
2, which can therefore be fully cooled with reduced
quantities of air streams.
Because sirocco fans of one-side suction type are used as the cooling fans
66 to
68 of the cooling unit
6, with a sufficiently large
space provided between the wall of the housing
60 and the fan side portions
having the intake openings
66a to
68a, the air drawn
in through the space S is offered reduced flow resistance. This consequently permits
the use of sirocco fans of low output and low speed of rotation as the respective
cooling fans.
The liquid crystal projector of the invention described above is improved in
the cooling system for cooling the lamp
5 and the optical unit
2
to ensure effective cooling with reduced quantities of air streams than in the
prior art. Accordingly, the fans for forcing out cooling air can be driven at a
lower speed of rotation. This serves to greatly reduce the noise to be produced
by the fans.
*
