US5721603A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Illumination system and display device including such a system
Assignee: US Philips Corp
•
Filing: 1996-12-17
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Granted: 1998-02-24
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Expires: 2016-12-17
Abstract
Abstract An illumination system comprising a reflector, a cholesteric filter and a depolarizer. The cholesteric filter is arranged between a radiation source and, in a display device, a display panel, and is selected to transmit radiation having a selected state of polarization in a selected wavelength range, while reflecting otherwise polarized radiation in that wavelength range. The depolarizer is disposed between the reflector and the cholesteric filter. Radiation reflected by the cholesteric filter is re-reflected to the filter by the reflector and, having been depolarized in the depolarizer, is transmitted to the extent it has the selected state of polarization in the selected wavelength.
Inventors
- 👤 Adrianus J.S.M. De Vaan
- 👤 Paulus B.J. Schaareman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:37
CPC Classifications
F; F21; F21V; F21V9/00; F21V9/14; G; G02; G02B; G02B5/00; G02B5/30; G02B5/3016; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/133528; G02F1/133536; G02F1/1336; G02F1/13362; H; H04; H04N; H04N5/00; H04N5/66; H04N9/00; H04N9/12; H04N9/31; H04N9/3141; H04N9/315; H04N9/3167; G02F1/133543
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
47 words
An illumination system for supplying an illumination beam having a selected state of polarization, which system successively comprises a reflector, a radiation source and a cholesteric filter, the filter active within the visible wavelength range, and a depolarizer arranged between the radiation source and the cholesteric filter.
Claim 2
Dependent Claim
47 words
An illumination system for supplying an illumination beam having a selected state of polarization, which system successively comprises a reflector, a radiation source and a cholesteric filter, the filter active within the visible wavelength range, and a depolarizer arranged between the radiation source and the cholesteric filter.
Claim 3
Dependent Claim
41 words
The illumination system of claim 1 in which the cholesteric filter comprises a plurality of layers of liquid crystalline material, each layer being active for a different wavelength band, which wavelength bands jointly cover at least substantially the visible wavelength range.
Claim 4
Dependent Claim
68 words
The illumination system of claim 1 in which the cholesteric filter comprises at least one layer of liquid crystalline polymer material comprising molecules in the form of a helix, within said layer the pitch of the helix varies between first and second values which correspond to the lower limit and the upper limit, respectively, of a reflection band necessary to cover at least substantially the visible wavelength range.
Claim 5
Dependent Claim
74 words
The illumination system of claim 3 in which the cholesteric filter comprises a plurality of layers, each layer comprising a liquid crystalline polymer material having molecules in the form of a helix, within said layer the pitch of the helix varies between first and second values which correspond to the lower limit and the upper limit, respectively, of a different wavelength band, said wavelength bands jointly cover at least substantially the visible wavelength range.
Claim 6
Dependent Claim
26 words
The illumination system of claim 3 in which the pitch varies continuously from the first value to the second value across the thickness of the layer.
Claim 7
Dependent Claim
24 words
The illumination system of claim 3 in which the polymer material of the cholesteric filter forms a self-supporting film of a three dimensional network.
Claim 8
Dependent Claim
74 words
The illumination system of claim 1 in which the cholesteric filter consists of a single layer, the layer comprising a liquid crystalline polymer material having molecules in the form of a helix, within said layer the pitch of the helix varies between first and second values which correspond to the lower limit and the upper limit, respectively, of a different wavelength band, said wavelength bands jointly cover at least substantially the visible wavelength range.
Claim 9
Dependent Claim
54 words
The illumination system of claim 2 or 3 in which an optically transparent element is arranged between the depolarizer and the cholesteric filter, the side of the element facing the filter having a periodical and radiation refracting structure extending in at least one direction for concentrating radiation from the depolarizer at a given angle.
Claim 10
Dependent Claim
79 words
An illumination system as claimed in claim 8, characterized in that the element is composed of a first plate of which a surface facing the filter has a first periodical structure which extends in a first direction in the plane of the plate, and a second plate of which a surface facing the filter has a second periodical structure which extends in a second direction in the plane of the plate and at an angle to the first direction.
Claim 11
Dependent Claim
29 words
An illumination system as claimed in claim 8, characterized in that the element is a single plate of which a surface facing the filter has a two-dimensional radiation-refracting structure.
Claim 12
Dependent Claim
46 words
An illumination system as claimed in claim 8, characterized in that the radiation-refracting structure is constituted by first surface areas which cover second surface areas, the first areas enclosing a first angle and the second areas enclosing a second angle with the normal on the element.
Claim 13
Dependent Claim
12 words
A display device incorporating the illumination system of claim 1 or 3.
Claim 14
Dependent Claim
21 words
The display device of claim 12 in which the cholesteric filter is active in at least substantially the visible wavelength range.
Claim 15
Dependent Claim
32 words
The display device of claim 12 having at least one transmission display panel, arranged at a side of the cholesteric filter remote from the depolarizer, for generating an image to be displayed.
Claim 16
Dependent Claim
16 words
The display device of claim 14 in which the transmission display panel is an LCD panel.
Claim 17
Dependent Claim
22 words
The display device of claim 15 in which a wideband λ/4 plate is arranged between the cholesteric filter and the LCD panel.
Claim 18
Dependent Claim
21 words
The display device of claim 15 in which a beam concentrating element is present between the depolarizer and the cholesteric filter.
Claim 19
Dependent Claim
22 words
The display device of claim 14 having at least one projection lens system for projecting the generated image on a projection screen.
Claim 20
Dependent Claim
22 words
The display device of claim 14 in which the transmission display panel is a color display panel having a matrix of pixels.
Claim 21
Dependent Claim
25 words
The display device of claim 19 in which a matrix of dichroic mirrors is arranged proximate to and in register with the matrix of pixels.
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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) | 2001-02-23 | 2001-08-25 | 2002-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-02-23 | 2005-08-25 | 2006-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-02-23 | 2009-08-25 | 2010-02-24 | $7700.00 | Window Closed / Lapsed |