US3723747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelectric detector with compensating photocell
Assignee: Electro Signal Lab Inc
•
Filing: 1971-06-03
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Granted: 1973-03-27
•
Expires: 1991-06-03
Abstract
Abstract A smoke detector with a first cell sensing light scattered from matter to be detected and a second compensating cell has an adjustable plug for varying light from a source to the compensating cell and a diffuser for spreading the adjusted light over the same area of the compensating cell as the area of the first cell exposed to scattered light.
Inventors
- 👤 D Steele
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:20
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/103; G08B17/107; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G08B17/11; G08B17/113; G01N2201/00; G01N2201/06; G01N2201/063; G01N2201/0638; G01N2201/0639
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
141 words
Apparatus for detecting particulate matter in a confined space comprising: a light source for illuminating the space, first and second solid state photosensitive devices having substantially equal light sensitive areas, the first of said devices being exposed over its total area to light scattered from matter in the space and the second device beinG exposed to light from the source, said devices being connected to an alarm circuit so that the second device compensates for variations in sensitivity of the first device, and means to control the amount of light on the second device, wherein said control means includes means to spread the controlled amount of light over substantially the same light sensitive area of the second device as the area of the first device exposed to light in said space, thereby to light age the two photosensitive devices substantially equally.
Claim 2
Dependent Claim
141 words
Apparatus for detecting particulate matter in a confined space comprising: a light source for illuminating the space, first and second solid state photosensitive devices having substantially equal light sensitive areas, the first of said devices being exposed over its total area to light scattered from matter in the space and the second device beinG exposed to light from the source, said devices being connected to an alarm circuit so that the second device compensates for variations in sensitivity of the first device, and means to control the amount of light on the second device, wherein said control means includes means to spread the controlled amount of light over substantially the same light sensitive area of the second device as the area of the first device exposed to light in said space, thereby to light age the two photosensitive devices substantially equally.
Claim 3
Dependent Claim
32 words
Apparatus according to claim 1 wherein said control means comprises means for adjusting light from said source, and said spreading means is between the adjusting means and the second light sensitive area.
Claim 4
Dependent Claim
26 words
Apparatus according to claim 1 wherein said control means comprises means for diffusing controlled light over substantially the entire light sensitive area of said second device.
Claim 5
Dependent Claim
13 words
Apparatus according to claim 1 wherein said spreading means comprises a light diffuser.
Claim 6
Dependent Claim
13 words
Apparatus according to claim 2 wherein said spreading means comprises a light diffuser.
Claim 7
Dependent Claim
14 words
Apparatus according to claim 1 wherein said spreading means comprises diffuse light transmitting means.
Claim 8
Dependent Claim
14 words
Apparatus according to claim 1 wherein said spreading means comprises diffuse light reflecting means.
Claim 9
Dependent Claim
15 words
Apparatus according to claim 1 wherein said spreading means comprises an internally light diffusing solid.
Claim 10
Dependent Claim
38 words
Apparatus according to claim 1 characterized by wall means forming a light passage between the light source and second device, adjustable means variably obstructing said passage, and diffusing means in said passage between the adjustable means and device.
Claim 11
Dependent Claim
18 words
Apparatus according to claim 9 wherein said spreading means comprises a diffuse reflecting surface on said wall means.
Claim 12
Dependent Claim
24 words
Apparatus according to claim 1 wherein said control means is adjustable through the range of light intensities normally falling on the first photosensitive device.
References Cited (Backward Citations)
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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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |