US3728703A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fire detector stabilizer circuit
Assignee: EDWARD CO Inc
•
Filing: 1970-10-12
•
Granted: 1973-04-17
•
Expires: 1990-10-12
Abstract
Abstract A fire detector has been provided including an ionization sensing means which changes the level of an output signal in accordance with the sensing of the presence of smoke particles in the atmosphere. A detecting means including a semi-conductor device selectively responds to the output signal and generates an alarm control signal. The improvement includes a very high frequency pump source coupled across the sensing and detecting means for stabilizing the ionization and to quench areas of intense ionization within the sensing means and the semiconductor.
Inventors
- 👤 J Burnett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 02:00
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
142 words
A fire detector stabilizer circuit comprising in combination: a. a smoke sensing device having an ionization detector for changing the output level of a signal in response to the presence of smoke in the atmosphere; b. detecting means including a semi-conductor device which is selectively responsive to the output level of said smoke sensing device for generating an alarm control signal; c. a DC potential for inducing a current flow in said smoke sensing device; d. a very high frequency source including an alternating current pump coupled across said smoke sensing device and said detecting means for quenching non-uniform ionization of said smoke sensing device; and wherein e. said alternating current pump produces a radio frequency signal at a voltage level substantially equal to, or slightly higher than, that of said DC potential and less than the bias level of said semi-conductor.
Claim 2
Dependent Claim
142 words
A fire detector stabilizer circuit comprising in combination: a. a smoke sensing device having an ionization detector for changing the output level of a signal in response to the presence of smoke in the atmosphere; b. detecting means including a semi-conductor device which is selectively responsive to the output level of said smoke sensing device for generating an alarm control signal; c. a DC potential for inducing a current flow in said smoke sensing device; d. a very high frequency source including an alternating current pump coupled across said smoke sensing device and said detecting means for quenching non-uniform ionization of said smoke sensing device; and wherein e. said alternating current pump produces a radio frequency signal at a voltage level substantially equal to, or slightly higher than, that of said DC potential and less than the bias level of said semi-conductor.
Claim 3
Dependent Claim
29 words
The Apparatus of claim 1 wherein said very high frequency source is coupled to the fire detector, by coupling means tuned to the frequency of the alternating current pump.
Claim 4
Dependent Claim
65 words
The apparatus of claim 2 wherein said semi-conductor is a field effect transistor having: a. a voltage level sensitive gate electrode coupled to the smoke sensing device and; b. output terminals coupled to the output of said alternating current pump; and wherein c. said field effect transistor achieves a conductance state in response to a predetermined variation of the voltage level of said gate electrode.
Claim 5
Dependent Claim
41 words
The apparatus of claim 3 wherein said smoke sensing device includes: two chambers including electrodes having the ionization potential imposed thereon serially coupled across the alternating current pump and having their junction coupled to the gate of said field effect transistor.
Claim 6
Dependent Claim
38 words
The apparatus of claim 2 wherein said coupling means includes: resistive and capacitive impedances for tuning the coupling means and said capacitive impedance further comprises inter-electrode capacitive effects of said chambers and junction capacitive effects of said semi-conductor.
Claim 7
Dependent Claim
53 words
The apparatus of claim 5 wherein said chambers comprise: a reference chamber substantially isolated from the smoke for establishing a reference potential; and a measuring chamber open to the atmosphere for producing a change in the potential at the junction of the chamber in accordance with the concentration of smoke in the atmosphere.
Claim 8
Dependent Claim
29 words
The apparatus of claim 4 wherein said detector further includes: output circuit means responsive to the conductance state of said field effect transistor for producing the alarm control signal.
Claim 9
Dependent Claim
60 words
The apparatus of claim 7 wherein said output circuit includes: a trigger circuit responsive to the conductance state of the field effect transistor for producing an output; and a control rectifier having a gate electrode coupled to the output of said trigger circuit assuming a conductance state upon the occurrence of the trigger output for producing said alarm control signal.
Claim 10
Dependent Claim
41 words
The apparatus of claim 8 wherein said trigger means and said control rectifier means include semi-conductor devices coupled therein, and said output circuit means is coupled across said alternating current pump output for further stabilizing the response of said semi-conductor devices.
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) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |