U.S. patent application number 09/728854 was filed with the patent office on 2002-06-06 for enhancing spectral luminosity in projection displays.
Invention is credited to O'Connor, Michael.
Application Number | 20020067468 09/728854 |
Document ID | / |
Family ID | 24928531 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020067468 |
Kind Code |
A1 |
O'Connor, Michael |
June 6, 2002 |
ENHANCING SPECTRAL LUMINOSITY IN PROJECTION DISPLAYS
Abstract
A light source used for projection displays that produces more
light of a particular color relative to one or more other colors
can be operated in a way to increase the performance of the overall
optical system. A first color component that is produced in a
lesser amount, may be separated out from the light and discarded
while the other light components may be modulated. A separate light
source may generate light of the first color that is modulated and
combined with the previously modulated color components.
Inventors: |
O'Connor, Michael;
(Cupertino, CA) |
Correspondence
Address: |
Timothy N. Trop
TROP PRUNER & HU, P.C.
8554 KATY FWY, STE 100
HOUSTON
TX
77024-1805
US
|
Family ID: |
24928531 |
Appl. No.: |
09/728854 |
Filed: |
December 1, 2000 |
Current U.S.
Class: |
353/31 ;
348/E9.027 |
Current CPC
Class: |
G03B 21/2026 20130101;
H04N 9/3105 20130101; H04N 9/3167 20130101 |
Class at
Publication: |
353/31 |
International
Class: |
G03B 021/00 |
Claims
What is claimed is:
1. A method comprising: receiving, from a light source, first light
including first and second color components; removing the first
color component from said first light; modulating the second color
component; generating second light of the first color; modulating
said second light; and combining said modulated second light and
the modulated first light.
2. The method of claim 1 wherein receiving first light from a light
source includes receiving first light from a light source which
generates more light of said first color component than said second
color component.
3. The method of claim 1 including receiving first light from a
ultra high pressure mercury halide arc lamp.
4. The method of claim 1 further including discarding the first
color component from said first light.
5. The method of claim 1 wherein generating second light of the
first color includes operating a light source which generates red
light.
6. The method of claim 1 wherein removing the first color component
from said first light includes converting the polarization of the
first color component and separating said first color component
based on polarization from said second color component.
7. The method of claim 1 wherein generating the second light occurs
after modulating the second color component.
8. The method of claim 1 including receiving, from a light source,
first light including first, second and third color components,
modulating said second and third color components and combining
said modulated second light and the modulated second and third
colors.
9. A modulation engine comprising: a first light source that
generates light including first and second color components; a beam
splitter that splits the first color component from the second
color component; a first modulator that modulates said second color
component; a second light source that generates light of said first
color; a second modulator that modulates said light from said
second source; and a combiner that combines said modulated light
from the first and second sources.
10. The engine of claim 9 including a polarizer that causes the
polarization of the first color component to be different than the
polarization of said second color component.
11. The engine of claim 9 wherein said first light source generates
more light of said first color component than said second color
component.
12. The engine of claim 9 wherein said first light source is a
mercury halide arc lamp.
13. The engine of claim 9 wherein said second light source is a red
laser source.
14. The engine of claim 9 wherein said first light source generates
light including first, second and third color components.
15. The engine of claim 9 wherein said second light source
generates primarily light of said first color.
16. The engine of claim 9 including an absorber that absorbs said
first color component of said first light source.
17. A projection display comprising: a first spatial light
modulator that modulates light of a first color component; a second
spatial light modulator that modulates light of a second color
component; a light source that generates light of a third color
component; and a device that combines said modulated lights of said
first, second and third color components.
18. The projection display of claim 17 including a first light
source that generates light including said first, second and third
color components, a polarizer that causes the polarization of the
first color component to be different from the polarization of said
second and third color components and a beam splitter that splits
the first color component from the second and third color
components.
19. The display of claim 17, wherein said first color component is
a red color component and said second and third color components
are blue and green color components.
20. The display of claim 17, wherein said first light source is a
mercury halide lamp and said second light source is a red laser
light source.
Description
BACKGROUND
[0001] This invention relates generally to projection displays.
[0002] Many projection display systems are driven by ultra high
pressure (UHP) mercury halide arc lamps. These arc lamps generate
most of their light in the green portion of the spectrum and very
little light in the red portion of the spectrum.
[0003] In order to produce display images that have color
temperatures meeting various display standards, the projection
systems discard a high percentage of the green light in order to
achieve the right color balance between the green, blue and red
components. This accommodation may decrease the brightness of the
display, complicate projection system design and limit the size of
the display that the arc lamp can power.
[0004] Thus, there is a need for better ways to utilize light
sources that generate light with an imbalance between the color
components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic depiction of one embodiment of the
present invention.
DETAILED DESCRIPTION
[0006] A light modulation engine 10 for a projection display
includes a lamp 12 that produces more light in one portion of the
spectrum than in another. For example, the lamp 12 may be an ultra
high pressure mercury halide arc lamp that produces more light in
the green portion of the spectrum and less light in the red portion
of the spectrum.
[0007] The blue and green randomly polarized light (B.sub.r,
G.sub.r) light generated by the lamp 12 is reflected from a cold
mirror 14. The cold mirror 14 passes red (R.sub.r), infrared (IR)
and ultraviolet (UV) components that are collected by an absorber
16. The blue and green randomly polarized light (G.sub.r, B.sub.r)
is reflected from the cold mirror 14 and is subjected to beam
conditioning by the optics 18 to transform it into a uniform
intensity beam with a shape matching the microdisplays 30, 32,
42.
[0008] The light (G.sub.r, B.sub.r) then interacts with a
polarization converter 20 that reflects the s polarizations
(G.sub.s, B.sub.s) and passes the p polarizations (G.sub.p,
B.sub.p).
[0009] The blue and green (G.sub.p, B.sub.p) components are then
passed through a lens 22 and input to a cyan notch dichroic filter
24 that removes a portion of the green spectrum that would be
presented to both the blue and green spatial light modulators 30,
32. The blue and green (G.sub.p, B.sub.p) components are then input
to a green polarization filter 26 that rotates the green component
(G.sub.p) to s polarization (G.sub.s) while leaving the
polarization of the blue component (B.sub.p) unchanged. The blue
and green light components (G.sub.s, B.sub.p) then transit a
polarization beam splitter (PBS) 28 where, the green component
(G.sub.s) is reflected by the polarizer of the splitter 28 to image
on the green spatial light modulator 30, and the blue component
(B.sub.p) passes through the polarizer of the splitter 28 to image
on the blue spatial light modulator 32.
[0010] The green spatial light modulator 30 serves to rotate the
polarization of the green light component (G.sub.s) back to p
polarization (G.sub.p) for those pixels that are "on". The "on"
green light component (G.sub.p) then transits the PBS 28 passing
through its polarizer, also passing through a Blue Twist
polarization filter 34 unchanged, and through the combining PBS 36
to contribute to the final image 48.
[0011] The green spatial light modulator 30 also serves to leave
the polarization of the green light component (G.sub.s) that images
to "off" pixels unchanged in the s polarization state (G.sub.s).
This "off" green light component (G.sub.s) is reflected by the PBS
28 polarizer back toward the light source 12 and does not
contribute to the final image.
[0012] The blue light component (B.sub.p) that passes through the
PBS 28 polarizer images on the blue spatial light modulator 32. The
blue spatial light modulator 32 serves to rotate the polarization
of the blue light component (B.sub.p) to the s polarization
(B.sub.s) for those pixels that are "on". The "on" blue light
component (B.sub.s) then reflects from the polarizer in the PBS 28
and passes through a Blue Twist polarization filter 34, where its
polarization is changed to p polarization (B.sub.p). It then passes
through the combining PBS 36 to contribute to the final image
48.
[0013] The blue spatial light modulator 32 also serves to leave the
polarization of the blue light component (B.sub.p) that images to
"off" pixels unchanged in the p polarization state (B.sub.p). This
"off" blue light component (B.sub.p) passes through the PBS 28
polarizer back toward the light source 12 and does not contribute
to the final image 48.
[0014] A red light component (R.sub.s) is introduced into a PBS 40
from a second light source 46 such as a red laser array or an arc
lamp. The conditioning, despeckling and imaging optics 44 serve to
put the red light component into the s polarization state if
needed, and to prepare the light to match the f number of the
imaging optics 22 used for the blue and green light components.
[0015] This red light component (R.sub.s) reflects from the PBS 40
polarizer to image to the red spatial light modulator 42. The red
spatial light modulator 42 serves to rotate the polarization of the
red light component (R.sub.s) back to p polarization (R.sub.p) for
those pixels that are "on". The "on" red light component (R.sub.p)
then transits the PBS 40 passing through its polarizer, also
passing through a half wave achromatic phase retarder, which
changes it back to the s polarization (R.sub.s). It then enters the
combining PBS 36 where it reflects from the PBS 36 polarizer
combining with the "on" green and blue spatial light components to
form the final image 48.
[0016] The red spatial light modulator 42 also serves to leave the
polarization of the red light component (R.sub.s) that images to
"off" pixels unchanged in the s polarization state (R.sub.s). This
"off" red light component (R.sub.s) is reflected by the PBS 28
polarizer back toward the light source 46 and does not contribute
to the final image.
[0017] The combined light output 48 may then be displayed on a
projection screen (not shown).
[0018] In embodiments of the present invention, the design of light
modulation engine 10 may be simplified. In addition, the brightness
standard display color temperatures may be increased in some
embodiments. Much larger display screens may be driven by arc lamps
used in projection systems in some cases. In addition, arc lamps
may be re-optimized for luminance efficiency to a condition where
they readily emit green and blue components, thus increasing their
light output and lifetime. By making the light source 46 emit a red
light with an tendue that matches that of the lamp 12 and light
modulation engine 10, light from the two light sources may be
effectively combined.
[0019] The light modulation engine 10 may dump red light from the
lamp 12 in an early optical stage and may re-introduce red light
from a second, high intensity source in a later optical stage. The
red light (R) from the second, high intensity source 46 is imaged
on the red spatial light modulator 42 and combined with modulated
blue and green beams (GB).
[0020] While the present invention has been described with respect
to a limited number of embodiments, those skilled in the art will
appreciate numerous modifications and variations therefrom. It is
intended that the appended claims cover all such modifications and
variations as fall within the true spirit and scope of this present
invention.
* * * * *