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US4745398A
Expired / Lapsed
US
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Self-powered sensor for use in closed-loop security system
Assignee: Sentrol Inc
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Filing: 1987-02-09
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Granted: 1988-05-17
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Expires: 2007-02-09
Abstract
Abstract A self-powered sensor for a closed-loop security system includes a self-powered sensor network which provides a switch-actuating signal upon the detection of a physical condition. An electronic switch, which is in a normally closed position, is connected between the positive and negative poles of a closed-loop security system and opens the loop upon receipt of the switch-actuating signal thereby triggering an alarm. The self-powered sensor network may include a voltage doubler for converting the AC output of a transducer to a DC voltage of an amplitude sufficient to open the switch. When the switch is opened, voltage from the closed-loop security system becomes available to power a visible or audible alarm identifying the sensor that opened the loop.
Inventors
- 👤 William E. Abel
- 👤 Douglas H. Marman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:07
CPC Classifications
G; G08; G08B; G08B23/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
164 words
A self-powered sensor for a closed-loop security system, comprising: (a) self-powered sensor network means for providing a switch actuating signal upon the detection of a physical condition wherein said self-powered sensor network means comprises transducer means, said transducer means having a pair of plates separated by a piezoelectric element and having a transient alternating current output, and voltage doubling circuit means responsive to the output of said transducer means, said pair of plates forming a charge storage element of said voltage doubling circuit means, for approximately doubling the peak voltage output of said transducer means to provide said switch actuating signal for a predetermined period of time; and (b) electronic switch means, said electronic switch means having a semiconductor junction forming a diode included in said voltage doubling circuit means, said electronic switch means being in a normally closed position thereby allowing current in said closed-loop security system to flow therethrough, for opening said closed-loop security system in response to said switch actuating signal.
Claim 2
Dependent Claim
164 words
A self-powered sensor for a closed-loop security system, comprising: (a) self-powered sensor network means for providing a switch actuating signal upon the detection of a physical condition wherein said self-powered sensor network means comprises transducer means, said transducer means having a pair of plates separated by a piezoelectric element and having a transient alternating current output, and voltage doubling circuit means responsive to the output of said transducer means, said pair of plates forming a charge storage element of said voltage doubling circuit means, for approximately doubling the peak voltage output of said transducer means to provide said switch actuating signal for a predetermined period of time; and (b) electronic switch means, said electronic switch means having a semiconductor junction forming a diode included in said voltage doubling circuit means, said electronic switch means being in a normally closed position thereby allowing current in said closed-loop security system to flow therethrough, for opening said closed-loop security system in response to said switch actuating signal.
Claim 3
Dependent Claim
15 words
The self-powered sensor of claim 1 wherein said electronic switch means comprises a JFET transistor.
Claim 4
Dependent Claim
16 words
The self-powered sensor of claim 1 wherein said electronic switch means comprises a depletion-mode MOSFET transistor.
Claim 5
Dependent Claim
25 words
The self-powered sensor of claim 1, further including shunt resistor means connected across said plates for providing a high pass filter for said transducer means.
Claim 6
Dependent Claim
43 words
The self-powered sensor of claim 1, further including alarm means associated with said sensor and coupled to said closed-loop security system wherein voltage made available by the opening of said closed loop security system is used to provide power for said alarm means.
Claim 7
Dependent Claim
21 words
The sensor of claim 5 wherein said alarm means comprises light-emitting diode means connected in parallel with said electronic switch means.
Claim 8
Dependent Claim
49 words
The sensor of claim 5 wherein said self-powered sensor network means includes piezoelectric transducer means and said alarm means comprises an oscillator coupled between said piezoelectric transducer means and a pole of said closed-loop security system for activating said piezoelectric transducer means so as to cause an audible sound.
Claim 9
Dependent Claim
62 words
The sensor of claim 2 wherein said closed-loop security system comprises a positive lead connected to a drain electrode of said JFET transistor and a negative lead connected to a source electrode of said JFET transistor and a voltage threshold detector connected between said positive and negative leads thereby forming a closed loop, said closed loop being powered by a current source.
Claim 10
Dependent Claim
44 words
The sensor of claim 1 wherein said self-powered sensor network means comprises a time delay means for maintaining said electronic switch means in an open position for a predetermined period of time after said switch means has been opened by said switch actuating signal.
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) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |