Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
2001-12-10
2003-11-25
Dowling, William (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S083000, C353S034000
Reexamination Certificate
active
06652103
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention herein relates to a reflective-type liquid crystal projection system.
2) Description of the Prior Art
According to the principles utilized during optical diffraction and focusing, the conventional liquid crystal projection television systems can be generally classified as transparent (TFT) or reflection (LCD) types. Since the transparent-type liquid crystal projection television systems were developed earlier, the components utilized in the said systems are more mature. However, with respect to the liquid crystal panels, since the resolution and clarity of reflective-type liquid crystal display panels is superior and, furthermore, lower in price, more and more liquid crystal projection television manufacturers plan to use reflective-type liquid crystal display panels designs.
Referring to
FIG. 1
, a conventional transparent-type TFT liquid crystal projection television system consists of a projection bulb
10
. The light generated by the said projection bulb
10
is passing through a filter lens group
11
and then sequentially passing through a reflection mirror
130
, a lens group
14
, and a dichroic mirror
150
after being filtered, such that the said light is diffracted into two beams of different wavelengths. After the one beam of light is sequentially passing a reflection mirror
133
and a convergent lens
160
, it is projected onto a red transparent-type liquid crystal display (R-TFT) panel
170
. The other beam of light is directed towards another dichroic mirror
151
and further diffracted into two beams of light. The said two beams of light are then passing through reflection mirrors
131
and
132
as well as the convergent lens
161
,
163
, and
164
, and are projected onto a green transparent-type liquid crystal display (G-TFT) panel
171
and a blue transparent-type liquid crystal display (B-TFT) panel
172
respectively. After diffraction, the said three beams of light travel through the red transparent-type liquid crystal display (R-TFT) panel
170
, the green transparent-type liquid crystal display (G-TFT) panel
171
, and the blue transparent-type liquid crystal display (B-TFT) panel
172
, and let the red, green and blue images shown thereon be projected to a polarizing beam splitter (PRS) prism
18
. The said polarizing beam splitter prism
18
merged these images into a single image, which is then penetrating a projection lens
190
and is projected onto a television screen
191
for viewing. Therefore, in a transparent-type TFT liquid crystal display projection television system, two dichroic mirrors
150
and
151
are utilized to diffract the light generated by the projection bulb
10
into three light beams of different wavelengths, such that the image of the said light beams reaching the red transparent-type liquid crystal display (R-TFT) panel
170
, the green transparent-type liquid crystal display (G-TFT) panel
171
, and the blue transparent-type liquid crystal display (B-TFT)
172
are projected to a polarizing beam splitter prism
18
and merged into a single image by the said polarizing beam splitter prism
18
.
Referring to
FIG. 2
, a conventional reflective-type LCD projection television system also consists of a projection bulb
20
. The light generated by the said projection bulb
20
is passing through a filter lens group
21
and then passing through a dichroic mirror
220
after being filtered, where the said light is diffracted into two light beams of different wavelengths. One beam thereof sequentially passes through a reflection mirror
230
and a convergent lens
240
, and is projected to a first polarizing beam splitter prism
250
. After passing the said prism
250
, the beam of light is reflected to a red reflective-type liquid crystal display (R-LCD) panel
260
. The other beam of light passes through the reflection mirrors
231
and
232
as well as another dichroic mirror
221
respectively, and is further diffracted into two beams of light. The said two beams of light then respectively pass through the convergent lens
241
and
242
and projected to a second and a third polarizing beam splitter prism
251
and
252
. The said two prisms
251
and
252
respectively reflect them to a green reflective-type liquid crystal display (G-LCD) panel
261
and a blue reflective-type liquid crystal display (B-LCD) panel
262
. After the said diffracted beams of light are projected onto the reflective-type liquid crystal display panels
260
,
261
and
262
, the red, green and blue images shown thereon are respectively reflected to a fourth polarizing beam splitter prism
27
through the said prisms
250
,
251
, and
252
. The said fourth polarizing beam splitter prism
27
merges these images into a single image, which is then penetrating a projection lens
28
and is projected onto a television screen for viewing.
As described above, although the said reflective-type liquid crystal display panel has superior resolution and clarity and, furthermore, the advantage of lower price, since the overall system utilizes a larger quantity of optical components and, furthermore, the optical structure is more complex, its physical dimensions are larger and thus its overall production cost is higher.
SUMMARY OF THE INVENTION
In view of the foregoing situation, to improve upon the shortcomings of the said conventional reflective-type liquid crystal projection system, the inventor of the invention herein conducted extensive research and testing that culminated in the successful design of the reflective-type liquid crystal projection system of the invention. The said system consists of a dichroic mirror that diffracts the light beam generated by a light source module into two colored light beams of different wavelengths; and three polarizing light flux splitter prisms that are symmetrically disposed around the dichroic prism as well as two related converging lens groups, such that the three RGB color images shown on three reflective-type liquid crystal display panels are merged into a single image and then projected onto a television screen for viewing. As a result, the structural design of the present invention is simpler and, furthermore, the overall physical dimensions are smaller than the conventional reflective-type liquid crystal projection television system, thereby effectively reducing production, storage, and shipping costs.
REFERENCES:
patent: 5863125 (1999-01-01), Doany
patent: 6247816 (2001-06-01), Cipolla et al.
patent: 6273567 (2001-08-01), Conner et al.
patent: 6327093 (2001-12-01), Nakanishi et al.
patent: 6343864 (2002-02-01), Tajiri
patent: 6375330 (2002-04-01), Mihalakis
patent: 6384972 (2002-05-01), Chuang
patent: 6390626 (2002-05-01), Knox
patent: 6419362 (2002-07-01), Ikeda et al.
Bacon & Thomas PLLC
Chunghwa Picture Tubes Ltd.
Dowling William
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