US3714433A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Nittan Co Ltd
•
Filing: 1970-09-28
•
Granted: 1973-01-30
•
Expires: 1990-09-28
Abstract
Abstract An ionization smoke detector having open and closed ionization chambers connected in series across a power supply, a field effect transistor having a gate connected to the junction of said chambers and a source-drain path connected to a power supply with current limiting means in series therewith to limit the maximum source-drain current resulting from gate leakage currents.
Inventors
- 👤 A Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:43
CPC Classifications
G; G01; G01T; G01T7/00; G01T7/12; G01T7/125; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
149 words
An ionization smoke detector, comprising a closed ionization chamber having a pair of electrodes and a radioactive source therein, an open ionization chamber having a pair of electrodes and a radioactive source therein and connected in series with said closed ionization chamber, a field effect transistor having a gate electrode connected to the junction of said ionization chambers and a source-drain conduction path connected in parallel with series connected ionization chambers, a silicon controlled rectifier having a gate electrode interconnected with and controlled by said field effect transistor and a conduction path connected in parallel with said series connected ionization chambers, means for connecting said series connected chambers to a voltage source and a constant current circuit in series with the source-drain conduction path of said field effect transistor, the last said circuit limiting the source-drain current of said field effect transistor throughout the normal gate leakage current range.
Claim 2
Dependent Claim
149 words
An ionization smoke detector, comprising a closed ionization chamber having a pair of electrodes and a radioactive source therein, an open ionization chamber having a pair of electrodes and a radioactive source therein and connected in series with said closed ionization chamber, a field effect transistor having a gate electrode connected to the junction of said ionization chambers and a source-drain conduction path connected in parallel with series connected ionization chambers, a silicon controlled rectifier having a gate electrode interconnected with and controlled by said field effect transistor and a conduction path connected in parallel with said series connected ionization chambers, means for connecting said series connected chambers to a voltage source and a constant current circuit in series with the source-drain conduction path of said field effect transistor, the last said circuit limiting the source-drain current of said field effect transistor throughout the normal gate leakage current range.
Claim 3
Dependent Claim
149 words
An ionization smoke detector, comprising a closed ionization chamber having a pair of electrodes and a radioactive source therein, an open ionization chamber having a pair of electrodes and a radioactive source therein and connected in series with said closed ionization chamber, a field effect transistor having a gate electrode connected to the junction of said ionization chambers and a source-drain conduction path connected in parallel with series connected ionization chambers, a silicon controlled rectifier having a gate electrode interconnected with and controlled by said field effect transistor and a conduction path connected in parallel with said series connected ionization chambers, means for connecting said series connected chambers to a voltage source and a constant current circuit in series with the source-drain conduction path of said field effect transistor, the last said circuit limiting the source-drain current of said field effect transistor throughout the normal gate leakage current range.
Claim 4
Dependent Claim
149 words
An ionization smoke detector, comprising a closed ionization chamber having a pair of electrodes and a radioactive source therein, an open ionization chamber having a pair of electrodes and a radioactive source therein and connected in series with said closed ionization chamber, a field effect transistor having a gate electrode connected to the junction of said ionization chambers and a source-drain conduction path connected in parallel with series connected ionization chambers, a silicon controlled rectifier having a gate electrode interconnected with and controlled by said field effect transistor and a conduction path connected in parallel with said series connected ionization chambers, means for connecting said series connected chambers to a voltage source and a constant current circuit in series with the source-drain conduction path of said field effect transistor, the last said circuit limiting the source-drain current of said field effect transistor throughout the normal gate leakage current range.
References Cited (Backward Citations)
US3530450A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |