US5576854A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal light valve projector with improved contrast ratio and with 0.27 wavelength compensation for birefringence in the liquid crystal light valve
Assignee: JVCKenwood Corp
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Filing: 1993-11-12
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Granted: 1996-11-19
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Expires: 2013-11-12
Abstract
Abstract In a liquid crystal light valve projector, a quarter-wave compensator plate is disposed between a polarization plate and a liquid crystal light valve to compensate for polarization irregularities induced by the off-incident reflections in the cone of light projected onto the LCLV. The quarter-wave compensation plate reverses the phase of the P component of said illumination light with respect to said compensator plate by 180° thereby eliminating P-polarization leakage during the dark state of an LCLV projector. The invention also combines the compensator plate with a heat shield and a low stress-optical coefficient counter electrode substrate to reduce the birefringence of the LCLV thereby also minimizing leakage of P-polarized light onto the projection screen during the dark state of the projector.
Inventors
- 👤 Jack H. Schmidt
- 👤 Ned Nestorovic
- 👤 Rodney D. Sterling
- 👤 Joseph M. Haggerty
- 👤 Javier A. Ruiz
- 👤 Robert Edwards
- 👤 Roger Hollister
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:58
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/133382; G02F1/133385; G02F1/1335; G02F1/133528; G02F1/135; G02F1/13363; G02F1/133638
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
204 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, compensator means disposed between said polarization means and said liquid crystal light valve means for changing the phase angle of the polarized light reflected from said polarization means through said compensator means to said liquid crystal light valve means and back through said compensator means to said polarization means wherein said compensator means has shifted the polarization of said reflected light so that said reflected light has a phase shift in its polarization of approximately 180°; and wherein said compensator means has a total retardance of greater than 0.25, wherein the additional retardance above 0.25 compensates for birefringence in the liquid crystal light valve means.
Claim 2
Dependent Claim
204 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, compensator means disposed between said polarization means and said liquid crystal light valve means for changing the phase angle of the polarized light reflected from said polarization means through said compensator means to said liquid crystal light valve means and back through said compensator means to said polarization means wherein said compensator means has shifted the polarization of said reflected light so that said reflected light has a phase shift in its polarization of approximately 180°; and wherein said compensator means has a total retardance of greater than 0.25, wherein the additional retardance above 0.25 compensates for birefringence in the liquid crystal light valve means.
Claim 3
Dependent Claim
28 words
The polarization based projection system of claim 1 wherein said compensator means has its fast axis perpendicular or parallel to the axis of polarization of the polarization means.
Claim 4
Dependent Claim
213 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, said liquid crystal light valve means having a counter electrode means having low thermally induced stress birefringence and a low stress-optical coefficient, compensator means disposed between said polarization means and said liquid crystal light valve means for changing the phase angle of the polarized light reflected from said polarization means through said compensator means to said polarization means wherein said compensator means has shifted the P-polarization of said reflected light so that said reflected light has a phase shift in its P-polarization of approximately 180°; and wherein said compensator means has a total retardance of greater than 0.25, wherein the additional retardance above 0.25 compensates for birefringence in the liquid crystal light valve means.
Claim 5
Dependent Claim
213 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, said liquid crystal light valve means having a counter electrode means having low thermally induced stress birefringence and a low stress-optical coefficient, compensator means disposed between said polarization means and said liquid crystal light valve means for changing the phase angle of the polarized light reflected from said polarization means through said compensator means to said polarization means wherein said compensator means has shifted the P-polarization of said reflected light so that said reflected light has a phase shift in its P-polarization of approximately 180°; and wherein said compensator means has a total retardance of greater than 0.25, wherein the additional retardance above 0.25 compensates for birefringence in the liquid crystal light valve means.
Claim 6
Dependent Claim
22 words
The polarization based projection system of claim 3 wherein said counter electrode means includes a counter electrode substrate made from SF-57 glass.
Claim 7
Dependent Claim
163 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, heat shield means located between said polarization means and said liquid crystal light valve means including an outer portion defining a first opening, said first opening for transmitting light to said light valve and said outer portion for absorbing stray light to reduce the temperature transferred to the liquid crystal light valve means thereby reducing the birefringence of said liquid crystal light valve means.
Claim 8
Dependent Claim
163 words
A polarization based projection system comprising: an illumination source for providing illumination light, polarization means disposed adjacent to said illumination means for directing polarized light from said illumination source, liquid crystal light valve means disposed adjacent to said polarization means for receiving polarized light reflected from said polarization means, said liquid crystal light valve being capable of altering the polarization state of the polarized illumination light reflected from said polarization means, projection lens for projecting light transferred from said liquid crystal light valve means through said polarization means to said projection lens for projecting an image on a screen, heat shield means located between said polarization means and said liquid crystal light valve means including an outer portion defining a first opening, said first opening for transmitting light to said light valve and said outer portion for absorbing stray light to reduce the temperature transferred to the liquid crystal light valve means thereby reducing the birefringence of said liquid crystal light valve means.
Claim 9
Dependent Claim
85 words
The polarization base projection system of claim 5 including compensator means disposed between said polarization means and said liquid crystal light valve means for changing the phase angle of the polarized light reflected from said polarization means through said compensator means to said liquid crystal light valve means and back through said compensator means to said polarization means wherein said compensator means has shifted the P-polarization of said reflected light so that said reflected light has a phase shift in its P-polarization of approximately 180°.
Claim 10
Dependent Claim
34 words
The polarization based projection system of claim 5 including: said liquid crystal light valve means having a counter electrode means including a substrate having low thermally induced stress birefringence and a low stress-optical coefficient.
Claim 11
Dependent Claim
17 words
The polarization base projection system of claim 7 wherein said counter electrode means substrate is SF-57 glass.
Claim 12
Dependent Claim
16 words
The polarization base projection system of claim 8 wherein said compensator means is a quarter-wave plate.
Claim 13
Dependent Claim
17 words
The polarization base projection system of claim 7 wherein said counter electrode means substrate is BK-7 glass.
Claim 14
Dependent Claim
36 words
The polarization based projection system of claim 6 wherein said compensator means has a total retardance of greater than 0.25 wherein the additional retardance above 0.25 compensates for birefringence in the liquid crystal light valve means.
Claim 15
Dependent Claim
85 words
A polarization based projection system comprising: a source of light; polarization means for receiving said light and for producing polarized light therefrom; a light valve located adjacent said polarization means for modulating said polarized light; and a heat shield, located between said light valve and said polarization means and including an outer portion defining a first opening, said first opening for transmitting light to said light valve and said outer portion for absorbing stray light to reduce the temperature and birefringence of said light valve.
Claim 16
Dependent Claim
85 words
A polarization based projection system comprising: a source of light; polarization means for receiving said light and for producing polarized light therefrom; a light valve located adjacent said polarization means for modulating said polarized light; and a heat shield, located between said light valve and said polarization means and including an outer portion defining a first opening, said first opening for transmitting light to said light valve and said outer portion for absorbing stray light to reduce the temperature and birefringence of said light valve.
Claim 17
Dependent Claim
48 words
The polarization based projection system of claim 12 further comprising: an aperture plate defining a second opening and being located between said light valve and said heat shield, wherein said first opening is larger than said second opening and said heat shield reduces heating of said aperture plate.
Claim 18
Dependent Claim
31 words
The polarization based projection system of claim 13 wherein the differences in size between said first and second openings is related to a cone angle of light produced by said source.
Claim 19
Dependent Claim
27 words
The polarization based projection system of claim 13 further comprising a dust cover, wherein said heat shield and said aperture plate are coupled to said dust cover.
Claim 20
Dependent Claim
18 words
The polarization based projection system of claim 12 wherein said outer portion of said heat shield is anodized.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-11-19 | 2000-05-20 | 2000-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-19 | 2004-05-20 | 2004-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-19 | 2008-05-20 | 2008-11-19 | $7700.00 | Window Closed / Lapsed |