US3631436A
Expired / Lapsed
US
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Gas-detecting device
Assignee: Individual
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Filing: 1970-07-14
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Granted: 1971-12-28
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Expires: 1990-07-14
Abstract
Abstract A gas-detecting device having a gas responsive semiconductor, a pair of electrodes in contact with the semiconductor, means for heating the semiconductor to stabilize its resistance at a predetermined value, time delay switching means and an alarm circuit and an impedance circuit interconnected with said electrodes and said switching means so that the impedance circuit will be connected with the semiconductor electrodes during the heating period and upon stabilization of the semiconductor the switching means will automatically and effectively disconnect the impedance circuit and substitute the alarm circuit.
Inventors
- 👤 Naoyoshi Taguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:49
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G08; G08B; G08B17/00; G08B17/10; G08B17/117
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
141 words
A gas-detecting device comprising a metal oxide semiconductor element having a resistance characteristic which changes in the presence of a contaminating gas in the ambient air, a pair of electrodes in contact with said semiconductor including means for producing a current flow through said semiconductor, means for heating said semiconductor to a predetermined temperature, an alarm circuit having a predetermined impedance, an impedance circuit having the same impedance as the alarm circuit and time delayed switching means interconnected with said alarm circuit, said impedance circuit and said electrodes, said switching means normally connecting said impedance circuit with said electrodes and maintaining the last said connection for a predetermined time after energizing said heating means and then automatically disconnecting said impedance circuit and substituting said alarm circuit whereby said alarm circuit will be activated upon a predetermined resistance change of said semiconductor.
Claim 2
Dependent Claim
141 words
A gas-detecting device comprising a metal oxide semiconductor element having a resistance characteristic which changes in the presence of a contaminating gas in the ambient air, a pair of electrodes in contact with said semiconductor including means for producing a current flow through said semiconductor, means for heating said semiconductor to a predetermined temperature, an alarm circuit having a predetermined impedance, an impedance circuit having the same impedance as the alarm circuit and time delayed switching means interconnected with said alarm circuit, said impedance circuit and said electrodes, said switching means normally connecting said impedance circuit with said electrodes and maintaining the last said connection for a predetermined time after energizing said heating means and then automatically disconnecting said impedance circuit and substituting said alarm circuit whereby said alarm circuit will be activated upon a predetermined resistance change of said semiconductor.
Claim 3
Dependent Claim
51 words
A gas-detecting device according to claim 1 wherein said time delay switching means includes a temperature-sensing element responsive to the temperature of said semiconductor element and a double throw switch actuated by said temperature changing element and connections between the last said switch and said impedance circuit and said alarm circuit.
Claim 4
Dependent Claim
17 words
A gas-detecting device according to claim 2 wherein said time delayed switching means includes a bimetallic element.
Claim 5
Dependent Claim
28 words
A gas-detecting devices according to claim 2 wherein said semiconductor element is enclosed within a perforated metal cap and said temperature-sensing element is thermally coupled to said cap.
Claim 6
Dependent Claim
58 words
A gas-detecting device according to claim 1 wherein said time delay switching means includes a first resistor having a positive temperature characteristic, a second resistor having a negative temperature characteristic, means thermally coupling said resistors to said semiconductor element and connections between said first resistor and said impedance circuit and between said second resistor and said alarm circuit.
Claim 7
Dependent Claim
20 words
A gas-detecting element according to claim 5 wherein said thermal coupling means comprises a metal cap enclosing said semiconductor element.
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) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |