Patent US4916580A successfully refreshed from Google Patents.
US4916580A
Expired / Lapsed
US
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Back-light device
Assignee: Hitachi Ltd
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Filing: 1988-09-22
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Granted: 1990-04-10
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Expires: 2008-09-22
Abstract
Abstract In order to make the brightness approximately uniform over a diffusion board, a back-light device is provided with a light transmission controlling film having a planar form in a shape of a projection of the lamp on the diffusion board. The film is disposed in parallel to the lamp axis between the lamp and the diffusion board.
Inventors
- 👤 Toshihiko Sano
- 👤 Soichiro Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:39
CPC Classifications
G; G09; G09F; G09F13/00; G09F13/04; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133602; G02F1/133611; G01; G01D; G01D11/00; G01D11/28; G02F1/133604; G02F1/133606
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
122 words
A back-light device comprising: a lamp emitting visible light rays; a diffusion board disposed on one side of said lamp in parallel to a lamp axis of said lamp in order to diffuse the emitted visible light rays; a reflector disposed on another side of said lamp for reflecting the emitted visible light rays towards said diffusion board; and a light transmission controlling film having a planar form in a shape of a projection of said lamp on said diffusion board, said film having a uniform light transmission coefficient and being disposed in parallel to said lamp axis between said lamp and said diffusion board in order distribute said brightness of said emitted visible light rays approximately uniformly over said diffusion board.
Claim 2
Dependent Claim
122 words
A back-light device comprising: a lamp emitting visible light rays; a diffusion board disposed on one side of said lamp in parallel to a lamp axis of said lamp in order to diffuse the emitted visible light rays; a reflector disposed on another side of said lamp for reflecting the emitted visible light rays towards said diffusion board; and a light transmission controlling film having a planar form in a shape of a projection of said lamp on said diffusion board, said film having a uniform light transmission coefficient and being disposed in parallel to said lamp axis between said lamp and said diffusion board in order distribute said brightness of said emitted visible light rays approximately uniformly over said diffusion board.
Claim 3
Dependent Claim
20 words
A back-light device according to claim 1, wherein said light transmission controlling film is disposed in contact with said lamp.
Claim 4
Dependent Claim
17 words
A back-light device according to claim 2, wherein said light transmission controlling film is a transparent film.
Claim 5
Dependent Claim
14 words
The back-light device according to claim 3, wherein said lamp is a fluorescent lamp.
Claim 6
Dependent Claim
17 words
A back-light device according to claim 2, wherein said light transmission controlling film is a smoked film.
Claim 7
Dependent Claim
14 words
The back-light device according to claim 5, wherein said lamp is a fluorescent lamp.
Claim 8
Dependent Claim
15 words
A back-light device according to claim 2, wherein said lamp is a U-shaped fluorescent lamp.
Claim 9
Dependent Claim
14 words
The back-light device according to claim 2, wherein said lamp is a fluorescent lamp.
Claim 10
Dependent Claim
17 words
A back-light device according to claim 1, wherein said light transmission controlling film is a transparent film.
Claim 11
Dependent Claim
14 words
The back-light device according to claim 9, wherein said lamp is a fluorescent lamp.
Claim 12
Dependent Claim
17 words
A back-light device according to claim 1, wherein said light transmission controlling film is a smoked film.
Claim 13
Dependent Claim
14 words
The back-light device according to claim 11, wherein said lamp is a fluorescent lamp.
Claim 14
Dependent Claim
15 words
A back-light device according to claim 1, wherein said lamp is a U-shaped fluorescent lamp.
Claim 15
Dependent Claim
69 words
A back-light device according to claim 1, in which said light transmission control film has a shape substantially symmetrical with respect to the lamp axis and has a width such that the angle between a plane containing an edge of said film and the lamp axis and a plane perpendicular to said diffusion board and passing through the lamp axis is substantially in a range of 30° to 60°.
Claim 16
Dependent Claim
14 words
The back-light device according to claim 14, wherein said lamp is a fluorescent lamp.
Claim 17
Dependent Claim
29 words
A back-light device according to claim 1, in which said light transmission control film has a light transmission coefficient of substantially in a range of from 80% to 92%.
Claim 18
Dependent Claim
14 words
The back-light device according to claim 16, wherein said lamp is a fluorescent lamp.
Claim 19
Dependent Claim
14 words
The back-light device according to claim 1, wherein said lamp is a fluorescent lamp.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-09 | 1993-10-09 | 1994-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-09 | 1997-10-09 | 1998-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-09 | 2001-10-09 | 2002-04-10 | $7700.00 | Window Closed / Lapsed |