Color wheel

Details Color wheel Color wheel

2002-07-23

2003-08-12

Adams, Russell (Department: 2851)

Optics: image projectors

Color filter

C348S743000, C359S889000

Reexamination Certificate

active

06604830

ABSTRACT:

BACKGROUND OF INVENTION
(a) Field of the invention
The invention relates to a color wheel with periodic color changes of light beam, and particularly to a color wheel producing original colors of light in a projection display device.
(b) Description of the Prior Art
In order to create color contrast in a projection display device, a color wheel is installed on the optical light path of a projection display device. Filter segments of various colors are installed on the periphery of the color wheel and are rotated around the central axis of the color wheel. By rotating filter segments on the color wheel, the filter segments are alternately inserted into the optical path and thereby the desired periodic color change is produced. Then the projection display device can adjust color contrast in coordination with light valve action.
FIG. 1
is a color wheel disclosed in U.S. Pat. No. 5,868,482. On a shaft
11
of a motor
10
, a holding device
12
is used for fixing a carrier
13
. On an outer edge area of the carrier
13
, there is a recess
18
with a balancing device that serves to compensate imbalances during high speed rotation of the color wheel. On an inside edge area of the carrier
13
, there is a ring recess
14
filled with adhesive. An adhesive film
16
on one end of each filter segments
15
is bonded to the ring recess
14
and can be accurately positioned radially and axially against the stop
19
on the inside edge area of the carrier
13
. Therefore, the filter segments
15
form a continuous ring. A ring
17
that covers the ring recess
14
is mounted to the stop
19
for fastening the filter segments
15
to construct a color wheel. As a result, the color wheel moves the ring recess
14
away from the light beam projecting path to avoid deterioration of adhesive due to the heat of light.
However, because of consumer demand for lightness, thinness, shortness and smallness, projection display devices have been miniaturized, so is the color wheel becoming smaller and smaller. Therefore, when high temperature light beam impinges on the downsized filter segments
15
, heat is rapidly conducted to the bonding ends of the filter segments
15
that are sealed on both sides and heat cannot be radiated resulting in rising temperature, so the adhesive becomes deteriorated because of the high temperature. Meanwhile, because one end of the filter segment
15
is coated with adhesive film
16
only on its one side to bond to the carrier
13
, and the carrier
13
is subjected to projection of stray and deviated light caused by noises or alignment tolerances, resulting in rising temperature on the metal carrier
13
consequently to deterioration of the adhesive. Furthermore, another side of the filter segments
15
is in direct contact with the ring
17
, and the adhesive has poor heat conduction much different than the heat conduction coefficient of the ring
17
, so there is a temperature difference between two sides of the bonding end of filter segments
15
, resulting in a thermal stress that causes the filter segments
15
to crack during high speed rotation. As a result, these defects degrade the quality of the product.
SUMMARY OF INVENTION
The objective of the invention is to provide a color wheel, by changing the position and size of a glued side of filter segment, and providing proper heat diffusing paths for the glued side, to prevent thermal stress and upgrade product quality.
Another objective of the invention is to provide a color wheel to avoid deterioration to the glue and upgrade product reliability by obstructing direct projection of light onto the glue and reserving clearances for heat insulation and diffuseness.
To achieve the above objectives, the invention has a motor with a rotating casing. Protruding from a center of an upper side of the rotating casing, there is a rotating shaft. One end of each fan-shaped filter segment is in contact with the rotating shaft, while one side of its lower surface is a formation of a glue area coated with glue, being glued onto the upper side of the motor, forming a rear clearance from the upper side, the sides of filter segments are joined to become a ring shape around the rotating shaft. The ring-shaped obstructing plate has a center hole that is mounted onto the rotating shaft, keeping a clearance from the filter segments, and there is a ring recess on the outside of the obstructing plate.


REFERENCES:
patent: 3982825 (1976-09-01), Mitchell
patent: 4800474 (1989-01-01), Bornhorst
patent: 5777694 (1998-07-01), Poradish
patent: 5868482 (1999-02-01), Edlinger et al.
patent: 5921650 (1999-07-01), Doany et al.
patent: 6024453 (2000-02-01), Edlinger et al.

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