US4306772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photochromic light lens
Assignee: Individual
•
Filing: 1978-07-13
•
Granted: 1981-12-22
•
Expires: 1998-07-13
Abstract
Abstract A negative photochromic material which is responsive to the ultraviolet portion of the daylight spectrum comprises part of the lens of a light fixture. The material which is of the normally dark type varies the translucence of the lens so that more lumens of light are transmitted through the lens under daylight lighting conditions than at night.
Inventors
- 👤 Roy M. Harrigan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:38
CPC Classifications
G; G02; G02B; G02B3/00; F; F21; F21S; F21S43/00; F21S43/20; F21S43/255; F21V; F21V9/00; F21V9/40; G02B1/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
141 words
Lighting apparatus which comprises: a housing; an incandescent source of light disposed in said housing; a lens carried on said housing, said lens having first and second sides, said first side being exposed to light radiated from said incandescent source of light, said second side of said lens being exposed to light in the ambient of said apparatus; and means for varying the light transmittance from said first side of said lens to said second side of said lens as a function of the light which said second side of said lens is exposed to from the ambient of said apparatus, said means for varying the light transmittance not being responsive to the light from said incandescent source of light, said means comprising a negative photochromic material which in the presence of ultraviolet light increases the light transmittance of said lens.
Claim 2
Dependent Claim
141 words
Lighting apparatus which comprises: a housing; an incandescent source of light disposed in said housing; a lens carried on said housing, said lens having first and second sides, said first side being exposed to light radiated from said incandescent source of light, said second side of said lens being exposed to light in the ambient of said apparatus; and means for varying the light transmittance from said first side of said lens to said second side of said lens as a function of the light which said second side of said lens is exposed to from the ambient of said apparatus, said means for varying the light transmittance not being responsive to the light from said incandescent source of light, said means comprising a negative photochromic material which in the presence of ultraviolet light increases the light transmittance of said lens.
Claim 3
Dependent Claim
27 words
The apparatus as described in claim 1 wherein said negative photochromic material increases transmittance only after sustained periods of exposure to ultraviolet light on said second side.
Claim 4
Dependent Claim
20 words
The apparatus as described in claim 1 wherein said photochromic material is carried on the surface of a glass support.
Claim 5
Dependent Claim
14 words
The apparatus as described in claim 1 wherein said photochromic material comprises Crystal Violet.
Claim 6
Dependent Claim
14 words
The apparatus as described in claim 1 wherein said photochromic material comprises Malachite Green.
Claim 7
Dependent Claim
13 words
The apparatus as described in claim 1 wherein said photochromic material comprises Fuchsin.
References Cited (Backward Citations)
US3365678A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-21 | 1985-06-22 | 1985-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-21 | 1989-06-22 | 1989-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-21 | 1993-06-22 | 1993-12-22 | $7700.00 | Window Closed / Lapsed |