Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
2003-09-04
2004-11-02
Gray, David (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S034000, C353S084000, C353S098000, C353S099000, C353S102000, C359S308000, C362S293000, C348S743000, C349S005000, C349S007000, C349S008000
Reexamination Certificate
active
06811263
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2002-53160, filed on Sep. 4, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a single-panel color image display apparatus, and more particularly, to a colored light separating device having high optical efficiency due to color scrolling and a single-panel color image display apparatus using the same.
2. Description of the Related Art
Projection type color image display apparatuses form an image by controlling the on/off operation of light emitted from a high-power lamp light source on a pixel-by-pixel basis using a micro display (which is also called a light valve) such as a liquid crystal display (LCD) or a digital micro display (DMD), magnify and project the image using a projection optical system, and provide a wide picture. Projection type color image display apparatuses are classified into a three-panel projection type and a single-panel projection type, depending on the number of micro displays.
In a general single-panel color image display apparatus, white light irradiated from a white light source is separated into red, green, and blue using a color wheel, and the three colors are sequentially sent to one micro display. The micro display operates according to the sequence of colors received, and forms an image.
The general single-panel color image display apparatus has a simpler structure and a smaller optical system than a three-panel color image display apparatus, which forms images for each color on three micro displays using an optical separation/combination system, but provides an optical efficiency of ⅓ less than that of the three-panel color image display apparatus due to the use of the color wheel. To solve the reduction problem of the optical efficiency in the general single-panel color image display apparatus using the color wheel, a single-panel color image display apparatus using a color scrolling technique has been proposed as shown in FIG.
1
.
In the color scrolling technique, white light is separated into a red colored light R, a green colored light G, and a blue colored light B, and the three colors are sent to different locations on a micro display, thus forming R, G, and B color bars. Further, the color bars are moved at a constant speed in a particular method so that an image may be formed after the R, G, and B colors for each pixel reach the micro display.
Referring to
FIG. 1
, in a conventional single-panel image display apparatus, white light emitted from a lamp light source
30
passes through first and second lens arrays
32
and
34
and a polarizing beam splitter array
35
and is condensed by a condensing lens
37
. The white light is separated into R, G, and B colors by first through fourth dichroic filters
39
,
42
,
69
, and
52
, and the R, G, and B colors are combined.
To be more specific, the red colored light R and the green colored light G are transmitted by the first dichroic filter
39
and travel along a first optical path l
1
, while the blue colored light B is reflected by the first dichroic filter
39
and travels along a second optical path l
2
. The red colored light R and the green colored light G on the first light path l
1
are separated by the second dichroic filter
42
. The red colored light R is transmitted by the second dichroic filter
42
and travels along the first light path l
1
. The green colored light G is reflected by the second dichroic filter
42
and travels along the third light path l
3
.
The green colored light G and the blue colored light B that travel along the second and third optical paths l
2
and l
3
, respectively, are transmitted and reflected, respectively, by the third dichroic filter
69
, and are thus combined. Finally, the R, G, and B light beams are combined by the fourth dichroic filter
52
. The combined light passes through a polarizing beam splitter
57
and is incident on a micro display
60
.
First through third prisms
44
,
65
, and
72
are disposed on the first through third optical paths l
1
, l
2
, and l
3
, respectively, and rotate at a uniform speed such that R, G, and B color bars are formed on the micro display
60
, and are scrolled due to the rotation of the first through third prisms
44
,
65
, and
72
.
As described above, in the conventional single-panel image display apparatus, while the white light emitted from the light source
30
is separated and combined by the first through fourth dichroic filters
39
,
42
,
69
, and
52
, color scrolling is performed as the first through third prisms
44
,
65
, and
72
disposed on the first through third optical paths l
1
, l
2
, and l
3
rotate.
The scrolling of the R, G, and B color bars due to the rotation of the first through third prisms
44
,
65
, and
72
is shown in FIG.
2
.
FIG. 2
shows the movement of the R, G, and B color bars formed on a surface of the micro display
60
when the prisms
44
,
65
, and
72
corresponding to the R, G, and B colors are synchronously rotated.
The micro display
60
processes image information for each pixel to synchronize with the movement of the R, G, and B color bars and forms an image. The formed image is magnified by a projecting lens (not shown) and projected on a screen (not shown).
As described above, the conventional single-panel image display apparatus has the structure in which light is separated into individual colors and the separated colors are combined. Relay lenses
41
,
47
,
50
,
54
,
61
,
67
,
70
, and
75
, which are disposed on optical paths between optical components, send light to the polarizing beam splitter
57
. Accordingly, optical paths are complicated, and multiple components are disposed on the complicated optical paths so that the conventional single-panel image display apparatus has a large optical system, and an assembling process of the multiple components is difficult.
Further, since color scrolling is performed due to the individual rotation of the three prisms
44
,
65
, and
72
, it is difficult to synchronize the driving of the micro display
60
with the three prisms
44
,
65
, and
72
.
That is, the color bars as shown in
FIG. 2
must be moved at a constant speed to form a color image using the color scrolling technique. However, since the conventional single-panel image display apparatus must synchronize the micro display
60
with the three prisms
44
,
65
, and
72
to perform scrolling, controlling the synchronization is difficult. Further, since the three prisms
44
,
65
, and
72
move in a circular motion, the color scrolling speed is not constant, thus impairing the quality of an image.
In addition, a large amount of noise is generated due to the driving of three motors to rotate the three prisms
44
,
65
, and
72
, and the manufacturing costs of the conventional single-panel image display apparatus using three motors is higher compared to a color wheel method using only one motor.
SUMMARY OF THE INVENTION
The present invention provides a colored light separating device having a simple structure for color scrolling and a single-panel color image display apparatus using the same.
According to an aspect of the present invention, a single-panel color image display apparatus includes a light source; a colored light separating device, which comprises a colored light separator having a plurality of dichroic filters to separate light emitted from the light source into a plurality of colored light beams and a driving device to drive the colored light separator to scroll the separated colored light beams; and a micro display, which controls light, which is separated by the colored light separator according to color and scrolled according to the driving of the colored light separator, on a pixel-by-pixel basis according to an input image signal and forms a color image.
The driving device may enable the colored light separator to move straight, pivot
Cho Kun-ho
Kim Dae-sik
Kim Sung-ha
Koval Melissa J
Staas & Halsey , LLP
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