Optics: image projectors – Temperature control – Blower
Reexamination Certificate
2001-11-13
2003-06-24
Adams, Russell (Department: 2851)
Optics: image projectors
Temperature control
Blower
C353S058000, C353S061000, C352S146000, C349S005000, C348S748000
Reexamination Certificate
active
06582082
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a projection system, more particularly to a projection system including a compact optical engine having enhanced heat dissipating efficiency.
2. Description of the Related Art
Conventional portable projection devices are developed in the trend of compactness to enhance portability thereof. However, compactness may entail certain disadvantages. Referring to
FIGS. 1
,
2
and
3
, in a conventional projection device
1
, light from a projector lamp
11
is directed into a housing
201
of an optical engine
2
for processing. The processed light is projected via a projection lens
20
disposed at a front end of the housing
201
onto a display screen
293
. During operation, the projector lamp
11
and certain components of the optical engine
2
will generate high heat. This is because the projector lamp
11
emits concentrated light which generates a large amount of heat, and the light from the projector lamp
11
which is incident on an image synthesizing area
27
within the housing
201
also produces heat. The heat must be dissipated to cool the relevant components. Otherwise, the color of the images to be projected, as well as the distribution of the light, will be adversely affected or, worse still, the relevant components will be severely damaged. Therefore, in the conventional projection device
1
, a first fan
12
is disposed adjacent to the projector lamp
11
for extracting the heat generated by the projector lamp
11
rearwardly, and a second fan
21
is disposed at a bottom portion of the housing
201
for drawing cool air from below into the image synthesizing area
27
to dissipate the heat via a top portion of the housing
201
so as to lower the temperature of the image synthesizing area
27
within the housing
201
. Operating power for the entire projection device
1
is supplied by a power supply unit
13
which is located in front of the projector lamp
11
and adjacent to the housing
201
in order to facilitate supply of power to the projector lamp
11
and the electronic circuits of the projection device
1
. As the power supply unit
13
also produces heat during operation, and as the heat produced thereby cannot be effectively drawn out by means of the first fan
12
which is disposed to dissipate the heat generated by the projector lamp
11
and which is located at a relatively far position, a third fan
29
is provided adjacent to the power supply unit
13
to draw in cool air so as to ensure good heat dissipation.
During operation, light from the projector lamp
11
is guided into the housing
201
of the optical engine
2
. A filter
22
is disposed in the housing
201
adjacent to a rear end of the housing
201
to filter the ultraviolet and infrared light components of the light from the projector lamp
11
, thereby permitting passage of only white light therethrough. The white light passes through a pair of spaced-apart light integrator lenses
23
for conversion into evenly distributed light that subsequently passes through a polarization state converter
24
. The polarized light is thereafter reflected by a mirror
25
, and passes through two spaced-apart light splitters
261
,
262
, which split the white light into first, second and third color components (e.g., red, green and blue color components) that continue to proceed to the image synthesizing area
27
. The first, second and third color components respectively reach first, second and third liquid crystal light valves
271
,
272
,
273
in the image synthesizing area
27
for light modulation. The modulated first, second and third color components are recombined by a light synthesizing prism
274
into an image beam, which is subsequently projected via the projection lens
20
onto the display screen
293
.
In the conventional projection device
1
as described above, during light modulation of the first, second and third color components, since the light incident on the first, second and third light valves
271
,
272
,
273
is intense and generates high heat, and since relevant components like the liquid crystal components and polarizers within the housing
201
are vulnerable to high heat, an undue rise in temperature will result in abnormal operation and inferior color presentation, or even damage to the components. Therefore, a good heat dissipation system is needed. The second fan
21
described above is intended for this purpose and is mounted on the bottom portion of the housing
201
below the light valves
271
,
272
,
273
to dissipate heat.
With further reference to
FIG. 2
, the optical components that are disposed inside the optical engine
2
to process the light from the projector lamp
11
define a device axis
291
. The projection lens
20
defines an image axis
292
that is offset from and that is at a slightly higher level than the device axis
291
so that the image beam is projected therefrom upwardly to achieve a projection effect such as that illustrated in
FIG. 3
, in which the light projected by the projection lens
20
onto the display screen
293
disposed vertically in front covers a projection field
294
that has a large portion located above the image axis
292
to facilitate viewing by a seated audience at eye level.
Given the aforesaid, the provision of the second fan
21
at the bottom portion of the housing
201
of the optical engine
2
increases the vertical thickness of the optical engine
2
and is therefore detrimental to the compactization of the projection device
1
as a whole.
In addition, since the second fan
2
draws a current of cool air upwardly in a single direction to dissipate the hot air inside the optical engine
2
, an air vent has to be provided in the top portion of the housing
201
. If the user inadvertently places an object, such as a document, on top of the housing
201
to thereby block the air vent, the light valves
271
,
272
,
273
and other components may overheat and become damaged.
SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is to provide an optical engine for use in a projection system, which is compact and which can enhance heat dissipating efficiency.
Another object of the present invention is to provide a projection system incorporating the aforesaid optical engine so as to overcome the above-mentioned drawbacks associated with the prior art.
According to one aspect of the present invention, an optical engine of this invention includes:
a housing having upper and lower surfaces, and front and rear ends;
a light splitting unit disposed in the housing adjacent to the rear end and adapted to split white light that enters the rear end of the housing into first, second and third color components;
first, second and third light modulators accommodated within the housing between the front and rear ends for respectively modulating the first, second and third color components received from the light splitting unit;
a color synthesizing prism disposed in the housing adjacent to the first, second and third light modulators for recombining the first, second and third color components modulated by the first, second and third light modulators to form an image beam;
a projection lens disposed at the front end of the housing and adapted to project the image beam onto a display screen; and
a fan unit mounted on the upper surface of the housing, the fan unit having an inlet port facing toward the first, second and third light modulators for drawing air upwardly so as to dissipate heat generated by the first, second and third light modulators, the fan unit further having an outlet port that is transverse to the inlet port for discharging the air drawn into the inlet port.
According to another aspect of the present invention, a projection system of this invention includes:
a housing having upper and lower surfaces, and front and rear ends;
a light source disposed adjacent to the rear end of the housing and operable so as to supply white light;
a light splitting unit disposed in the housing adjacent to the rear
Tiao Kuo-Tung
Wang Cheng
Adams Russell
Koval Melissa J
Merchant & Gould P.C.
Prokia Technology Co., Ltd
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