Patent US5822029A successfully refreshed from Google Patents.
US5822029A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Illumination system and display device
Assignee: Sharp Corp
•
Filing: 1995-12-29
•
Granted: 1998-10-13
•
Expires: 2015-12-29
Abstract
Abstract An illumination system includes a polarized light source which emits circularly polarized light of a particular handedness and a cholesteric filter having a region arranged to transmit circularly polarized light falling within a first wavelength band and to reflect other wavelengths of circularly polarized light. A reflector redirects the reflected light back towards the cholesteric filter. The cholesteric filter can include a first layer having portions which reflect red, green and blue light while transmitting other colors, and a second layer identical to the first layer but out of alignment therewith so that each region of the filter transmits only one color of light, the other colors being reflected.
Inventors
- 👤 Gillian Margaret Davis
- 👤 Kathryn Walsh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:25
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/13362; G02B; G02B5/00; G02B5/30; G02B5/3016; G02F1/133621; G02F1/133528; G02F1/133536; G02F1/133543
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
118 words
An illumination system comprising: a polarized light source for emitting circularly polarized light; a cholesteric filter having a first region which transmits circularly polarized light of a wavelength falling within a first predetermined band and reflects light having a wavelength falling outside of the first band, and a second region which transmits circularly polarized light of a wavelength falling within a second predetermined band different from the first predetermined band and reflects light having a wavelength falling outside of the second band; and a reflector for returning the light reflected by the cholesteric filter towards the cholesteric filter, wherein the boundary between the first region and the second region is a plane parallel to a direction of illumination.
Claim 2
Dependent Claim
118 words
An illumination system comprising: a polarized light source for emitting circularly polarized light; a cholesteric filter having a first region which transmits circularly polarized light of a wavelength falling within a first predetermined band and reflects light having a wavelength falling outside of the first band, and a second region which transmits circularly polarized light of a wavelength falling within a second predetermined band different from the first predetermined band and reflects light having a wavelength falling outside of the second band; and a reflector for returning the light reflected by the cholesteric filter towards the cholesteric filter, wherein the boundary between the first region and the second region is a plane parallel to a direction of illumination.
Claim 3
Dependent Claim
24 words
An illumination system as claimed in claim 1, wherein the reflector returns the light reflected by the cholesteric filter towards the second region thereof.
Claim 4
Dependent Claim
53 words
An illumination system as claimed in claim 1, wherein the cholesteric filter further comprises at least one further region which transmits circularly polarized light of a wavelength falling within a respective predetermined band different to the first and second bands, and reflects light of a wavelength falling outside of the respective predetermined band.
Claim 5
Dependent Claim
49 words
An illumination system as claimed in claim 1, wherein the reflector and the cholesteric filter are arranged to repeatedly reflect light of a predetermined wavelength therebetween until the light of the predetermined wavelength is incident upon a region of the cholesteric filter transmitting the light of the predetermined wavelength.
Claim 6
Dependent Claim
74 words
An illumination system as claimed in claim 1, wherein each of the first region and the second region of the cholesteric filter comprises a plurality of layers, each of the layers transmitting circularly polarized light of a wavelength falling outside of a predetermined range and reflecting circularly polarized light of a wavelength falling within the predetermined range, the band of wavelengths transmitted by all of the layers defining the predetermined range for that region.
Claim 7
Dependent Claim
24 words
An illumination system as claimed in claim 5, wherein each of the layers comprises a film superimposed upon an adjacent one of the layers.
Claim 8
Dependent Claim
15 words
An illumination system as claimed in claim 5, wherein the cholesteric filter comprises two layers.
Claim 9
Dependent Claim
52 words
An illumination system as claimed in claim 5, wherein each of the layers of the cholesteric filter comprises a plurality of portions, each of the portions transmitting circularly polarized light of a wavelength falling outside of a respective range and reflecting circularly polarized light of a wavelength falling within the predetermined range.
Claim 10
Dependent Claim
39 words
An illumination system as claimed in claim 8, wherein the portions overlap with one another such that each of the first region and the second region of the cholesteric filter is defined by an overlapping part of the portions.
Claim 11
Dependent Claim
18 words
An illumination system as claimed in claim 1, wherein the cholesteric filter comprises a cholesteric liquid crystal polymer.
Claim 12
Dependent Claim
27 words
An illumination system as claimed in claim 1, wherein the light source comprises a fluorescent source for emitting light of wavelengths falling within substantially distinct wavelength bands.
Claim 13
Dependent Claim
27 words
An illumination system as claimed in claim 11, wherein at least one of the distinct wavelength bands is within the first predetermined band of the cholesteric filter.
Claim 14
Dependent Claim
16 words
An illumination system as claimed in claim 1, wherein the light source comprises a circular polarizer.
Claim 15
Dependent Claim
16 words
An illumination system as claimed in claim 13, wherein the circular polarizer is an absorbing polarizer.
Claim 16
Dependent Claim
22 words
An illumination system as claimed in claim 14, wherein the absorbing polarizer comprises an absorbing plane polarizer and a quarter wave plate.
Claim 17
Dependent Claim
16 words
An illumination system as claimed in claim 13, wherein the circular polarizer is a reflecting polarizer.
Claim 18
Dependent Claim
39 words
An illumination system as claimed in claim 16, wherein the reflecting polarizer comprises a cholesteric mirror which transmits circularly polarized light of a first handedness and reflects circularly polarized light of a second handedness opposite to the first handedness.
Claim 19
Dependent Claim
34 words
An illumination system as claimed in claim 17, wherein the cholesteric mirror includes a first layer reflecting light of the first wavelength band and a second layer reflecting light of the second wavelength band.
Claim 20
Dependent Claim
36 words
An illumination system as claimed in claim 18, wherein the cholesteric mirror further comprises at least one additional layer, the at least one additional layer reflecting light of wavelength falling within a respective additional predetermined band.
Claim 21
Dependent Claim
18 words
An illumination system as claimed in claim 16, wherein the reflecting polarizer comprises a polarization selective holographic element.
Claim 22
Dependent Claim
16 words
An illumination system as claimed in claim 20, wherein the holographic element transmits circularly polarized light.
Claim 23
Dependent Claim
28 words
An illumination system as claimed in claim 20, wherein the holographic element transmits plane polarized light, and wherein the polarized light source further comprises a quarter wave plate.
Claim 24
Dependent Claim
34 words
An illumination system as claimed in claim 13, wherein the handedness of the circularly polarized light transmitted by the circular polarizer is the same as that of the light transmitted by the cholesteric filter.
Claim 25
Dependent Claim
33 words
An illumination system as claimed in claim 13, wherein the handedness of the circularly polarized light transmitted by the circular polarizer is opposite to that of the light transmitted by the cholesteric filter.
Claim 26
Dependent Claim
25 words
An illumination system as claimed in claim 23, further comprising converting means for converting the circularly polarized light from one handedness to the opposite handedness.
Claim 27
Dependent Claim
17 words
An illumination system as claimed in claim 25, wherein the converting means comprises a half wave plate.
Claim 28
Dependent Claim
26 words
An illumination system as claimed in claim 1, wherein the reflector converts the polarization of the light incident thereon from one handedness to the opposite handedness.
Claim 29
Dependent Claim
17 words
A display device comprising an illumination system as claimed in claim 1 and a spatial light modulator.
Claim 30
Dependent Claim
18 words
A display device as claimed in claim 28, wherein the spatial light modulator comprises a liquid crystal display.
Claim 31
Dependent Claim
19 words
A display device as claimed in claim 29, wherein the cholesteric filter is integral with the liquid crystal display.
Claim 32
Dependent Claim
24 words
A display device as claimed in claim 29, further comprising reflective material for reflecting light away from non-transmissive parts of the liquid crystal display.
Claim 33
Dependent Claim
49 words
A display device as claimed in claim 31, further comprising quarter wave retarders disposed in front of the reflective material relative to the direction of light incident upon the reflective material so that the light passes through the quarter wave retarders before and after reflection from the reflective material.
References Cited (Backward Citations)
US3679290A
Cited
US3669525A
Cited
US5054888A
Cited
US4987410A
Cited
US5295009A
Cited
US5235443A
Cited
US5267060A
Cited
US5221982A
Cited
JPH0566476A
Cited
GB2260203A
Cited
EP0578302A1
Cited
JPH06130424A
Cited
US5325218A
Cited
EP0606940A2
Cited
EP0634674A2
Cited
US5486935A
Cited
US5619355A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-12 | 2002-04-13 | 2002-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-12 | 2006-04-13 | 2006-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-12 | 2010-04-13 | 2010-10-13 | $7700.00 | Window Closed / Lapsed |