Non-collinear light engine for color imaging systems

Details Non-collinear light engine for color imaging systems Non-collinear light engine for color imaging systems

2003-01-24

2004-08-24

Adams, Russell (Department: 2851)

Optics: image projectors

Polarizer or interference filter

C353S033000

Reexamination Certificate

active

06779893

ABSTRACT:

BACKGROUND
This invention relates generally to light engines for projection display systems, and more specifically to light engines for use with color imaging systems.
Typically, a light source is used for a light engine, enabling projection of images in a display system. As such, many types of light engines may provide light to project color images for a variety of projection display systems, including a color imaging system. An example of such a light engine is a collinear light engine that is shown in
FIG. 1
in connection with a color imaging system
5
according to a prior art projection display system. In this example, the prior art system
5
utilizes a light source
10
, such as an ultra high-pressure (UHP) lamp
10
to provide light. At the output region of the light source
10
, a set of optical components may be disposed, forming an input light beam. The set of optical components may include an ultraviolet and infrared (UV-IR) filter
12
, a light pipe homogenizer
14
, a color switch or color wheel
16
, and a lens
18
by way of one example. However, many of these optical components may have alternate forms. In the configuration shown in
FIG. 1
, a conventional polarizer, such as an output polarization analyzer
20
may serve to pass the light of a first polarization “P” while skipping or reflecting the light of a second polarization “S.” The color switch
16
in combination with the output polarization analyzer
20
may ideally pass red light through, for example, and selectably switch or alternate between either passing blue light and reflecting green light or passing green light and reflecting blue light.
The prior art system
5
may further include an imaging pre-filter, i.e., an RC1 filter
22
which is deployed in the output region of the lens
18
. A polarization beam splitter (PBS)
24
with a first side facing the RC1 filter
22
may additionally be provided thereafter. In the same way, on a second side of the PBS
24
, a quarter-wave (&lgr;/4, &lgr; being the wavelength) retarder
26
and a first spatial light modulator (SLM)
28
may be located. Yet another quarter-wave retarder
30
and a second SLM
32
may be provided on a third side of the PBS
24
. In operation, an electronic drive may present to the first SLM
28
image data that alternates between blue and green image data, while the second SLM
32
may be presented only with red image data. A clean-up polarizer
38
, and a projection lens
40
may be configured on a fourth side of the PBS
24
to provide an output beam based on a particular electronic drive, presenting image data in a specific format including a red-blue-green (RGB) format, as one example.
Taken together, the prior art system
5
may typically be said to include a light engine incorporating the elements
10
,
12
and
14
, a color switch subsystem including the elements
16
,
18
and
20
, an imaging subsystem or kernel comprising the elements
22
through
38
, and a projection subsystem that includes element
40
. In particular, the color switch subsystem may be said to have an input axis (Axis
IKin
) through the first side of the PBS
24
, and the light source
10
which may be said to have an output axis (Axis
LEout
) through the light pipe homogenizer
14
. Because the in put axis of the color switch subsystem is in a coaxial or a collinear orientation with respect to the output axis of the light source
10
, the prior art system
5
is usually characterized as a collinear panel-based projection display system.
As such, for a host of projection display systems including a panel-based color imaging system depicted in
FIG. 1
, among other design features, contrast ratio is often a significant design feature. However, leakage of light with an incorrect polarization through the color switch
16
and the output polarization analyzer
20
typically contributes to the background leakage illumination, reducing the contrast ratio. For example, if the color switch
16
imperfectly switches between blue and green, some amount of the reflected color light may pass through to the first SLM
28
while it is still modulating the earlier passed color light.
In the prior art system
5
, the color switch
16
while passing green light (on the left) may undesirably reflect blue light (on the right), causing the blue leakage light (B
L
) to appear in the output beam from the projection lens
40
. Because of the architectural configuration of this system
5
, imperfections in the operation of the output polarization analyzer
20
may further contaminate the output beam. The input filter (UV-IR filter
12
) may also improperly reflect the “S” polarization green light (on the left, shown as a dashed line). As a result, this green light leakage may strike the first SLM
28
along with the “P” polarization green light, reflecting both the green light and leakage thereof into the output beam (shown as G
L
and G, respectively). Therefore, leakage of light with the incorrect polarization, onto the spatial light modulators and into the output beam may cause undesirable degradation of a projected image in a panel-based color imaging system.
Thus, there is a continuing need for better ways to configure light engines for use with projection display systems, especially in connection with color imaging systems.


REFERENCES:
patent: 6144420 (2000-11-01), Jung
patent: 6176583 (2001-01-01), Sawai
patent: 6217174 (2001-04-01), Knox
patent: 6243198 (2001-06-01), Sedlmayr
patent: 6262851 (2001-07-01), Marshall
patent: 6347013 (2002-02-01), Hannah
patent: 6362920 (2002-03-01), Hannah
patent: 6547399 (2003-04-01), Knox
patent: 6568815 (2003-05-01), Yano

Affiliated with

Also associated with

Rating

Non-collinear light engine for color imaging systems does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Non-collinear light engine for color imaging systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-collinear light engine for color imaging systems will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3292642