US4123656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Storage type smoke detector
Assignee: Hochiki Corp
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Filing: 1977-07-06
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Granted: 1978-10-31
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Expires: 1997-07-06
Abstract
Abstract In a storage type smoke detector which requires a predetermined time after an ionization smoke sensor detects a fire before a fire warning is issued, a charging circuit including a capacitor connected to a power supplying line is coupled with a discharging circuit for periodically discharging a voltage charged in the capacitor, and the discharging circuit is periodically closed by a P-channel type field effect transistor which is connected to an output end the ionization smoke sensor and which is supplied with a series of oscillating pulse.
Inventors
- 👤 Shigeru Kajii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:42
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
196 words
A storage type smoke detector comprising: a switching circuit connected between a pair of connection terminals of said detector, for shorting the pair of connection terminals upon receipt of a predetermined voltage, an oscillator circuit connected in parallel to said switching circuit, for producing a series of pulses, an ionization smoke sensor connected in parallel to said switching circuit, a P-channel type field effect transistor having a gate connected to an output end of said ionization smoke sensor and a source received a series of pulses from said oscillator circuit, a charging circuit including a capacitor connected in series to said connection terminals, for charging to a predetermined voltage effective to activate said switching circuit, a discharging circuit connected in parallel to said capacitor, for discharging a capacitor voltage by receiving an output pulse from a drain of said P-channel type field effect transistor, and means connected between the source of said field effect transistor and said oscillator circuit, for periodically switching on said field effect transistor, whereby the P-channel type field effect transistor periodically switches on to discharge the capacitor voltage until said transistor turns off by receiving the output from said ionization smoke sensor.
Claim 2
Dependent Claim
196 words
A storage type smoke detector comprising: a switching circuit connected between a pair of connection terminals of said detector, for shorting the pair of connection terminals upon receipt of a predetermined voltage, an oscillator circuit connected in parallel to said switching circuit, for producing a series of pulses, an ionization smoke sensor connected in parallel to said switching circuit, a P-channel type field effect transistor having a gate connected to an output end of said ionization smoke sensor and a source received a series of pulses from said oscillator circuit, a charging circuit including a capacitor connected in series to said connection terminals, for charging to a predetermined voltage effective to activate said switching circuit, a discharging circuit connected in parallel to said capacitor, for discharging a capacitor voltage by receiving an output pulse from a drain of said P-channel type field effect transistor, and means connected between the source of said field effect transistor and said oscillator circuit, for periodically switching on said field effect transistor, whereby the P-channel type field effect transistor periodically switches on to discharge the capacitor voltage until said transistor turns off by receiving the output from said ionization smoke sensor.
Claim 3
Dependent Claim
43 words
A storage type smoke detector according to claim 1, in which means for applying a series of the pulses to said P-channel type field effect transistor is interposed in said charging circuit for supplying said pulses both to said transistor and said capacitor.
Claim 4
Dependent Claim
34 words
A storage type smoke detector according to claim 1, in which said discharging circuit includes a transistor for closing said discharging circuit by receiving the periodical output from said P-channel type field effect transistor.
Claim 5
Dependent Claim
82 words
A storage type smoke detector according to claim 1, in which said switching circuit comprises a thyristor and a voltage division means in parallel connected between the pair of connection terminals and a PUT having an anode connected to the positive side of said capacitor; a gate to an output point of said voltage division means; and a cathode to a gate of said thyristor for shorting the pair of connection terminals upon receipt of the predetermined voltage charged in said capacitor.
References Cited (Backward Citations)
US3872449A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-30 | 1982-05-01 | 1982-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-30 | 1986-05-01 | 1986-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-30 | 1990-05-01 | 1990-10-31 | $7700.00 | Window Closed / Lapsed |