US5050946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Faceted light pipe
Assignee: Hewlett Packard Development Co LP
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Filing: 1990-09-27
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Granted: 1991-09-24
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Expires: 2010-09-27
Abstract
Abstract A light pipe (100) used for backlighting liquid crystal displays (D) has a planar front surface (110) and a stepped or faceted back surface (112). Light is injected from the ends (105) of the light pipe from cold or hot cathode, apertured, fluorescent lamps (108). The cold cathode lamps are preferably insulated to raise their operating temperature. The back surface has a series of planar portions (114) parallel to the front surface connected by facets (116), which are angled so that the injected light reflects off the facets and through the front surface. A reflector (126) having a planar, highly reflective, highly scattering surface or a sawtoothed or grooved upper surface is located adjacent to and parallel with the light pipe back surface to reflect light escaping from the back surface back through the light pipe to exit the front surface. The axes any grooves are preferably slightly skewed from the facet axis to reduce moire pattern development. A low scattering or loss diffuser (111) is located adjacent to and parallel with the light pipe front surface to reduce moire pattern development. The liquid crystal display (D) is located over the low scattering diffuser. A separate injector (104) may be located between the lamp and the light pipe to better couple the light into the light pipe. <IMAGE>
Inventors
- 👤 Kevin J. Hathaway
- 👤 Richard M. Knox, Jr.
- 👤 Douglas A. Arego
- 👤 Gaylon R. Kornfuerhrer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:22
CPC Classifications
G; G09; G09F; G09F13/00; G02; G02B; G02B6/00; G02B6/0001; G02B6/0011; G02B6/0033; G02B6/0035; G02B6/0045; G02B6/0046; G02B6/0048; F; F21; F21V; F21V7/00; G02B6/005; G02B6/0055; G02B6/0066; G02B6/0051; Y; Y10; Y10S; Y10S385/00; Y10S385/901
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
131 words
A system for backlighting a liquid crystal display, comprising: a light pipe having a generally planar front surface for providing light to the liquid crystal display, having a faceted back surface wherein said back surface includes a plurality of generally planar portions parallel to said front surface and a plurality of facets formed at an angle to said front surface and located connecting said back surface parallel portions, and having at least one end surface for receiving light to be transmitted through said front surface; light source means located adjacent each said end surface for receiving light of said light pipe for providing light to said light pipe; and reflector means located adjacent to and generally parallel to said light pipe back surface for reflecting light back through said light pipe.
Claim 2
Independent Claim
131 words
A system for backlighting a liquid crystal display, comprising: a light pipe having a generally planar front surface for providing light to the liquid crystal display, having a faceted back surface wherein said back surface includes a plurality of generally planar portions parallel to said front surface and a plurality of facets formed at an angle to said front surface and located connecting said back surface parallel portions, and having at least one end surface for receiving light to be transmitted through said front surface; light source means located adjacent each said end surface for receiving light of said light pipe for providing light to said light pipe; and reflector means located adjacent to and generally parallel to said light pipe back surface for reflecting light back through said light pipe.
Claim 3
Dependent Claim
50 words
The system of claim 1, wherein said reflector means is generally planar and has a front surface adjacent to said light pipe back surface, said reflector means front surface including a series of grooves, the longitudinal axis of said grooves extending somewhat parallel to the longitudinal axis of said facets.
Claim 4
Dependent Claim
22 words
The system of claim 2, wherein the longitudinal axis of said grooves is somewhat askew of the longitudinal axis of said facets.
Claim 5
Dependent Claim
35 words
The system of claim 1, wherein said reflector means is generally planar and has a front surface adjacent to said light pipe back surface, said reflector means front surface being highly reflective and highly scattering.
Claim 6
Independent Claim
33 words
The system of claims 3 or 4, further comprising: injector means between said light source means and said light pipe for coupling light produced by said light source means to said light pipe.
Claim 7
Dependent Claim
18 words
The system of claim 5, wherein said injector means has a flat surface facing said light source means.
Claim 8
Dependent Claim
17 words
The system of claim 6, wherein said injector means flat surface is coated with an anti-reflective coating.
Claim 9
Dependent Claim
25 words
The system of claim 5, wherein said injector means includes index matching material located between and contacting said light source means and said light pipe.
Claim 10
Dependent Claim
22 words
The system of claim 5, wherein said injector means is shaped to generally conform to the surface of said light source means.
Claim 11
Dependent Claim
18 words
The system of claim 5, wherein said injector means includes a surface having a fresnel lens developed thereon.
Claim 12
Dependent Claim
14 words
The system of claim 10, wherein said fresnel lens is a cylindrical fresnel lens.
Claim 13
Independent Claim
22 words
The system of claims 3 or 4, wherein each said end for receiving light of said light pipe has a flat surface.
Claim 14
Dependent Claim
14 words
The system of claim 12, wherein said end is coated with an anti-reflective coating.
Claim 15
Dependent Claim
14 words
The system of claim 12 wherein said end has a fresnel lens developed thereon.
Claim 16
Dependent Claim
13 words
The system of claim 14, wherein said fresnel lens is a cylindrical lens.
Claim 17
Independent Claim
31 words
The system of claims 3 or 4, wherein each said end for receiving light of said light pipe is shaped to generally conform to the surface of said light source means.
Claim 18
Independent Claim
15 words
The system of claims 3 or 4, wherein said light source means includes fluorescent lamps.
Claim 19
Dependent Claim
11 words
The system of claim 17, wherein said lamps are reflector lamps.
Claim 20
Dependent Claim
11 words
The system of claim 17, wherein said lamps are aperture lamps.
Claim 21
Dependent Claim
12 words
The system of claim 17, wherein said lamps are cold cathode lamps.
Claim 22
Dependent Claim
13 words
The system of claim 20, wherein said lamps are partially encompassed by insulation.
Claim 23
Dependent Claim
15 words
The system of claim 21, wherein said insulation includes a reflective surface facing said lamps.
Claim 24
Dependent Claim
12 words
The system of claim 17, wherein said lamps are hot cathode lamps.
Claim 25
Independent Claim
17 words
The system of claims 3 or 4, wherein said light source means includes uniform dispersion fluorescent lamps.
Claim 26
Dependent Claim
23 words
The system of claim 24, wherein said light means further includes reflectors formed around said lamps to reflect light to said light pipe.
Claim 27
Independent Claim
16 words
The system of claims 3 or 4, wherein said light pipe is formed of polymethyl methacrylate.
Claim 28
Independent Claim
23 words
The system of claims 3 or 4, wherein the angle of said facets from said parallel portion is between 90 and 180 degrees.
Claim 29
Dependent Claim
12 words
The system of claim 27, wherein the angle is approximately 135 degrees.
Claim 30
Independent Claim
31 words
The system of claims 3 or 4, wherein the pitch defined by the distance from successive facets is less than that required to exceed the visual threshold of a human being.
Claim 31
Dependent Claim
11 words
The system of claim 29, wherein said pitch is randomly varied.
Claim 32
Dependent Claim
19 words
The system of claim 29, wherein said pitch is uniformly varied to a maximum of approximately 1000 per inch.
Claim 33
Independent Claim
20 words
The system of claims 3 or 4, wherein the facet height between successive parallel portions is varied between two limits.
Claim 34
Dependent Claim
16 words
The system of claim 32, wherein said facet height limits are approximately 1 and 100 microns.
Claim 35
Independent Claim
23 words
The system of claims 3 or 4, further comprising a diffuser located adjacent to and generally parallel to said light pipe front surface.
Claim 36
Dependent Claim
23 words
The system of claim 1, further comprising a low scattering diffuser located adjacent to and generally parallel to said light pipe front surface.
Claim 37
Independent Claim
13 words
The system of claims 3 or 4, wherein said facets are generally planar.
Claim 38
Independent Claim
17 words
The system of claims 3 or 4, wherein said facets are portions of a generally cylindrical surface.
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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) | 1994-09-23 | 1995-03-25 | 1995-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-23 | 1999-03-25 | 1999-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-23 | 2003-03-25 | 2003-09-24 | $7700.00 | Window Closed / Lapsed |