Optics: image projectors – Color filter
Reexamination Certificate
2000-04-26
2003-06-10
Dowling, William (Department: 2851)
Optics: image projectors
Color filter
C353S031000, C348S743000
Reexamination Certificate
active
06575579
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a projecting device, and more specifically, to a projecting device with a cylindrical color tube for displaying color images.
2. Description of the Prior Art
Commonly, images are displayed by a projecting device by projection onto a screen. The projecting device can display images of various colors.
Please refer to
FIGS. 1
to
3
.
FIG. 1
is a perspective view of a prior art projecting device
10
.
FIG. 2
is a schematic diagram of the projecting device
10
.
FIG. 3
is a front view of the color wheel
18
in FIG.
2
.
The projecting device
10
comprises a housing
12
, a light source
14
installed in the housing
12
for generating a trichrome light beam
16
, a color wheel
18
rotatably installed in the housing
12
having red, green and blue dichroic filters
20
,
22
,
24
installed on a surface of the color wheel
18
for filtering the trichrome light beam
16
into red, green and blue light beams
26
, an electric motor
28
installed in the housing
12
for rotating the color wheel
18
so as to generate the red, green and blue light beams
26
one by one, a digital micro-mirror device (DMD)
30
installed in the housing
12
for converting an image signal into an image and modulating the image into each of the red, green and blue light beams
26
outputted from the color wheel
18
to generate a modulated light beam
32
, and a projecting lens
34
installed in the housing
12
for projecting the modulated light beam
32
onto a screen
36
.
The color wheel
18
can filter the trichrome light beam
16
into the red, green and blue light beams
26
one by one. However, the red, green and blue dichroic filters
20
,
22
,
24
each occupy a sector-shaped portion of the color wheel
18
. Therefore, when filtering the light beam
16
, it cannot pass through the center of the color wheel
18
. Thus the color wheel
18
has to be made very large, increasing the size of the projecting device
10
. The projecting device
10
is quite unmarketable because of its large size.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a projecting device to solve the above mentioned problem.
Briefly, in a preferred embodiment, the present invention provides a projecting device comprising a cylindrical color tube for filtering a trichrome light beam transmitted from a light source. The color tube has red, green and blue dichroic filters installed along its cylindrical side. When the trichrome light beam is transmitted through the color tube, it will be filtered into red, green and blue light beams. The red, green and blue light beams will be modulated to generate a modulated light beam. And the modulated light beam will be projected onto a screen.
It is an advantage of the present invention that the color tube has a very small size, reducing the size of the projecting device. This allows the projecting device to be quite marketable because of its small size.
REFERENCES:
patent: 2535530 (1950-12-01), Clark et al.
patent: 5463433 (1995-10-01), Koo
patent: 5921650 (1999-07-01), Doany et al.
patent: 6266105 (2001-07-01), Gleckman
Dowling William
Hsu Winston
Primax Electronics Ltd.
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