Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
2001-04-17
2002-10-01
Adams, Russell (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S020000, C359S490020, C359S634000
Reexamination Certificate
active
06457831
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a projection display, more particularly a single-lens projection display that utilizes reflective light modulators.
2. Description of the Related Art
In a conventional projection display, an input light beam, which contains red, green and blue color components, is processed before providing the same to a projection lens so as to generate an output image.
Referring to
FIG. 1
, a conventional single-lens projection display
1
is shown to include a first light polarization selector
11
, a second light polarization selector
12
, a polarization beam splitter prism
13
, a dichroic beam splitter prism
14
, a first light modulator
15
, a second light modulator
16
, a third light modulator
17
, a polarizer
18
, and a projection lens
19
. An input light beam
10
, which is a white light beam, is separated into first, second and third color components
101
,
102
,
103
, such as red, green and blue color components, for processing by the first, second and third light modulators
15
,
16
,
17
, respectively.
Each of the first and second light polarization selectors
11
,
12
, such as the ColorSelect™ filter products available from ColorLink Inc., serves to convert the polarization state of a predetermined color component, without altering the polarization state of the other color components. In the projection display
1
of
FIG. 1
, the polarization state of the third color component
103
, such as the green color component, is changed, whereas the polarization state of the first and second color components
101
,
102
remains unaltered, after the color components
101
,
102
,
103
pass through the first and second light polarization selectors
11
,
12
.
The polarization beam splitter prism
13
reflects light of a first polarization state, such as S-polarized light, in a transverse direction, and allows light of a second polarization state, such as P-polarized light, to pass therethrough.
The dichroic beam splitter prism
14
is used to separate two different color components. In the projection display
1
of
FIG. 1
, the dichroic beam splitter prism
14
allows the first color component
101
to pass directly therethrough, and reflects the second color component
102
in a transverse direction, thereby separating the first color component
101
from the second color component
102
.
Each of the first, second and third light modulators
15
,
16
,
17
is a reflective light valve, and is disposed adjacent to one of the dichroic beam splitter prism
14
and the polarization beam splitter prism
13
so as to receive a respective one of the first, second and third color components
101
,
102
,
103
therefrom. When activated, each of the first, second and third light modulators
15
,
16
,
17
modulates the respective one of the first, second and third color components
101
,
102
,
103
, and changes the polarization state of the respective one of the first, second and third color components
101
,
102
,
103
. The first, second and third light modulators
15
,
16
,
17
then reflect modulated first, second and third color components
101
,
102
,
103
back to the adjacent one of the dichroic beam splitter prism
14
and the polarization beam splitter prism
13
.
The polarizer
18
allows light of a predetermined polarization state to pass therethrough, and absorbs light of the other polarization state. In the projection display
1
of
FIG. 1
, the polarizer
18
allows P-polarized light to pass therethrough, and absorbs S-polarized light.
In operation, when the first light polarization selector
11
receives the S-polarized white input light beam
10
, the S-polarization state of the first and second color components
101
,
102
, such as the red and blue color components, remains unaltered, whereas the S-polarization state of the third color component
103
, such as the green color component, is changed to the P-polarization state, after the first, second and third color components
101
,
102
,
103
pass through the first light polarization selector
11
. The polarization beam splitter prism
13
receives the S-polarized first and second color components
101
,
102
and the P-polarized third color component
103
from the first light polarization selector
11
at a first side thereof, reflects the S-polarized first and second color components
101
,
102
in a transverse direction such that the S-polarized first and second color components
101
,
102
pass through a second side thereof, and permits the P-polarized third color component
103
to pass directly through a third side thereof opposite to the first side.
The dichroic beam splitter prism
14
, which is disposed adjacent to the second side of the polarization beam splitter prism
13
, receives the S-polarized first and second color components
101
,
102
therefrom. The first color component
101
passes directly through the dichroic beam splitter prism
14
, whereas the second color component
102
is reflected by the dichroic beam splitter prism
14
in a transverse direction.
The first and second light modulators
15
,
16
are disposed adjacent to the dichroic beam splitter prism
14
so as to receive the S-polarized first and second color components
101
,
102
respectively therefrom. The first and second light modulators
15
,
16
modulate the respective one of the first and second color components
101
,
102
, and change the polarization state of the respective first or second color component
101
,
102
from the S-polarization state to the P-polarization state when the first and second light modulators
15
,
16
are activated. The first and second light modulators
15
,
16
reflect the corresponding modulated color component back to the dichroic beam splitter prism
14
for reception by the polarization beam splitter prism
13
.
The third light modulator
17
is disposed adjacent to the third side of the polarization beam splitter prism
13
so as to receive the P-polarized third color component
103
therefrom. The third light modulator
17
modulates the third color component
103
, and changes the polarization state of the third color component
103
from the P-polarization state to the S-polarization state when the third light modulator
17
is activated. The third light modulator
17
reflects the modulated S-polarized third color component
103
back to the polarization beam splitter prism
13
.
The modulated P-polarized first and second color components
101
,
102
from the dichroic beam splitter prism
14
will be allowed by the polarization beam splitter prism
13
to pass directly through a fourth side thereof opposite to the second side for reception by the second light polarization selector
12
. The modulated S-polarized third color component
103
from the third light modulator
17
will be reflected by the polarization beam splitter prism
13
in a transverse direction so as to pass through the fourth side thereof for reception by the second light polarization selector
12
.
When the second light polarization selector
12
receives the modulated first, second and third color components
101
,
102
,
103
from the polarization beam splitter prism
13
, the polarization state of the modulated P-polarized first and second color components
101
,
102
remains unaltered, whereas the polarization state of the modulated S-polarized third color component
103
will be changed to the P-polarization state.
The polarizer
18
permits only pure P-polarized color components to pass therethrough, and absorbs S-polarized color components. The modulated P-polarized first, second and third color components
101
,
102
,
103
from the polarizer
18
are recombined as they pass through the projection lens
19
for projecting a color image on a display screen (not shown).
In the conventional projection display
1
, the dichroic beam splitter prism
14
and the polarization beam splitter prism
13
cooperate with the first and second light polarization selectors
11
,
12
to separate the white input light be
Chan Sheng-Hsiung
Chuang Fu-Ming
Adams Russell
Foley & Lardner
Prokia Technology Co., Ltd.
Sever Andrew
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