Vapor or particle detection device
Abstract
Abstract A VAPOR, SMOKE OR PARTICLE DETECTION DEVICE OF THE TYPE COMPRISING A BLACK-WALLED CHAMBER CONTAINING A LIGHT SOURCE AND A PHOTOCONDUCTIVE CELL, ARRANGED TO DETECT LIGHT FROM THE SOURCE WHEN REFLECTED FROM PARTICLES PRESENT IN THE CHAMBER, AND INCLUDING A SELF-BALANCING CONTROL CIRCUIT FOR ACTUATING AN ALARM WHEN THE DETECTION SIGNAL FROM THE PHOTOCONDUCTIVE CELL EXCEEDS A GIVE LEVEL. THE SENSITIVITY OR THRESHOLD LEVEL OF THE ALARM CONTROL CIRCUIT IS MAINTAINED CONSTANT DESPITE WIDE VARIATIONS IN THE APPLIED OPERATING VOLTAGE BY MEANS OF A VOLTAGE DIVIDING BRIDGE AR- RRANGEMENT USING AN INSULATED-GATE FIELD EFFECT TRANSISTOR FOR OPERATING THE GATE OF A CONTROLLED RECTIFIER WHICH CONTROLS CURRENT FLOW TO THE ALARM DEVICE. ALSO PROVIDED IN COMBINATION ARE MEANS FOR INTERMITTENTLY OPERATING THE LIGHT SOURCE FOR LONGER BATTERY LIFE, A HIGH TEMPERATURE DETECTION ELEMENT AND A FAIL-SAFE MECHANISM FOR SIGNALLING WHEN THE DEVICE IS INOPERATIVE.
Inventors
- 👤 George S White
- 👤 Richard E Lewis
- 👤 Lincoln M Zonn
Bibliographic Details
Claims Analysis
Total Claims: 0References 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) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |