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US5856855A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Edge-lit illumination system containing cholesteric polarizer and diffuser behind waveguide
Assignee: US Philips Corp
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Filing: 1996-08-23
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Granted: 1999-01-05
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Expires: 2016-08-23
Abstract
Abstract An illumination system (3) comprises an optical waveguide (9) of an optically transparent material having an exit surface (19) and four end faces (13, 14, 15, 16). The light from a light source (11) is coupled into the optical waveguide (9) via at least one of the end faces (13). The illumination system, for an LCD, further has a reflective polarizer (21) in combination with a diffuser (23) for polarizing the light supplied by the light source (11). The reflective polarizer (21) is integrated with the optical waveguide and constitutes the surface (25) of the optical waveguide (9) which is located opposite the exit surface (19). The diffuser (23) is present on a surface of the polarizer (21) remote from the optical waveguide (9).
Inventors
- 👤 Grietje N. Mol
- 👤 Dirk J. Broer
- 👤 Christianne R.M. De Witz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 12:56
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/0001; G02B6/0011; G02B6/0033; G02B6/0056; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; F; F21; F21V; F21V9/00; F21V9/14; G02B5/00; G02B5/02; G02B5/0205; G02B5/021; G02B5/0221; G02B5/0273; G02B5/0284; G02B5/30; G02B5/3025; G02B5/3033; G02F1/1336; G02F1/13362; G02B6/005; G02B6/0051; G02F1/133528; G02F1/133536; G02F1/133543; G02F1/13355
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
110 words
An illumination system comprising an optical waveguide of an optically transparent material having an exit surface and a plurality of end faces, opposite at least one of which a light source is situated, whose light can be coupled in at said end face of the optical waveguide, and polarizing means integrated with the optical waveguide for polarizing the light emitted by the light source, characterized in that the polarizing means are constituted by a reflective polarizer which is present on the surface of the optical waveguide located opposite the exit surface of the optical waveguide, a surface of the polarizer remote from the optical waveguide being provided with a diffuser.
Claim 2
Dependent Claim
110 words
An illumination system comprising an optical waveguide of an optically transparent material having an exit surface and a plurality of end faces, opposite at least one of which a light source is situated, whose light can be coupled in at said end face of the optical waveguide, and polarizing means integrated with the optical waveguide for polarizing the light emitted by the light source, characterized in that the polarizing means are constituted by a reflective polarizer which is present on the surface of the optical waveguide located opposite the exit surface of the optical waveguide, a surface of the polarizer remote from the optical waveguide being provided with a diffuser.
Claim 3
Dependent Claim
26 words
An illumination system as claimed in claim 1, characterized in that a reflector is arranged at the side of the diffuser remote from the reflective polarizer.
Claim 4
Dependent Claim
19 words
An illumination system as claimed in claim 2, characterized in that the reflector is a polarization-rotating or depolarizing reflector.
Claim 5
Dependent Claim
22 words
An illumination system as claimed in claim 2, characterized in that the reflector is a foil comprising particles which reflect substantially completely.
Claim 6
Dependent Claim
31 words
An illumination system as claimed in claim 1, characterized in that a reflector which has a depolarizing effect is arranged on at least one end face remote from a light source.
Claim 7
Dependent Claim
18 words
An illumination system as claimed in claim 1, characterized in that the reflective polarizer is a cholesteric polarizer.
Claim 8
Dependent Claim
64 words
An illumination system as claimed in claim 6, characterized in that the cholesteric polarizer is implemented as a single layer of a liquid crystalline polymer material, within which layer the pitch of the molecular helix varies substantially continuously between two values which correspond to the lower limit and the upper limit, respectively, of the reflection band required to cover the full visible wavelength range.
Claim 9
Dependent Claim
26 words
An illumination system as claimed in claim 6, characterized in that the illumination system comprises an n.λ/4 plate, in which n is an integral, odd number.
Claim 10
Dependent Claim
24 words
An illumination system as claimed in claim 8, characterized in that the n.λ/4 plate is present on the exit surface of the optical waveguide.
Claim 11
Dependent Claim
24 words
An illumination system as claimed in claim 8, characterized in that the n.λ/4 plate is present between the cholesteric layer and the optical waveguide.
Claim 12
Dependent Claim
19 words
An illumination system as claimed in claim 8, characterized in that the n.λ/4 plate functions as an optical waveguide.
Claim 13
Dependent Claim
41 words
An illumination system as claimed in claim 1, characterized in that the reflective polarizer is a linear polarizer which is implemented as a stack of layers comprising a birefringent material, or as a stack of layers being alternately birefringent and non-birefringent.
Claim 14
Dependent Claim
27 words
An illumination system as claimed in claim 1, characterized in that the diffuser is a thin film which is provided on the surface of the reflective polarizer.
Claim 15
Dependent Claim
25 words
An illumination system as claimed in claim 1, characterized in that the diffuser is a light-diffusing structure provided in the surface of the reflective polarizer.
Claim 16
Dependent Claim
23 words
An illumination system as claimed in claim 14, characterized in that the light-diffusing structure is constituted by a pattern of discrete diffusing areas.
Claim 17
Dependent Claim
58 words
A flat-panel picture display device including an illumination system provided with a picture display panel for modulating the direction of polarization of light generated by the illumination system in conformity with picture information to be displayed, and an analyzer, characterized in that the illumination system is an illumination system as claimed in any one of the preceding claims.
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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) | 2002-01-04 | 2002-07-06 | 2003-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-01-04 | 2006-07-06 | 2007-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-01-04 | 2010-07-06 | 2011-01-05 | $7700.00 | Window Closed / Lapsed |