US3699569A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Security system for indicating fire, intrusion or the like
Assignee: 3M Co
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Filing: 1972-01-28
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Granted: 1972-10-17
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Expires: 1992-01-28
Abstract
Abstract A fire-intrusion system of the type including at least one electrically continuous closed-loop for detecting the presence of an intruder and at least one electrically continuous closed-loop for detecting a fire wherein breaches in security indicative of fire and intrusion are sensed by a change in potential at a point in their respective loops. Potential sensing circuits are provided which are responsive to a changed or abnormal potential to indicate a fire, intrusion or inoperative circuit condition.
Inventors
- 👤 John H Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:05
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/02; G08B19/00
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
342 words
An electronic security system for detecting a breach in security within a closed-loop circuit having a plurality of sensors which may short or open said closed-loop in response to said breach wherein the improvement comprises an electronic device responsive to said sensors for producing an alarm signal when one of said sensors is opened or shorted, said electronic device comprising: a. a bistable multivibrator means connected in said closed-loop having a first normal state representing that said closed-loop circuit is neither open nor short circuited and a second state representing that said circuit is either short or open circuited, said multivibrator means adapted to provide as said alarm signal an output signal representative of said second state and including first and second cross-coupled transistors, said first transistor being in a conducting state during said multivibrator first normal state; b. a source of potential; c. a unidirectional conducting device connected between a point on said closed-loop circuit and to the base of said first transistor, said unidirectional conducting device being in a non-conducting state when the potential with respect to ground of said point on said circuit is at a normal level; d. potential dividing means connected between said source of potential and said point; and e. a switching transistor having a base coupled to said potential dividing means and having collector and emitter leads coupled in series between said source of potential and the base of said first transistor, the normal potential at said point causing said switching transistor to conduct to provide current to the base of said first transistor; said unidirectional conducting device switching to a conducting state to divert current from the base of said first transistor in response to said closed-loop becoming short circuited and said switching transistor switching to a nonconducting state to block current flow to the base of said first transistor in response to said closed-loop becoming open circuited, said multivibrator means switching to said second state to produce said alarm signal whenever the base current flow of said first transistor is diverted or blocked.
Claim 2
Dependent Claim
342 words
An electronic security system for detecting a breach in security within a closed-loop circuit having a plurality of sensors which may short or open said closed-loop in response to said breach wherein the improvement comprises an electronic device responsive to said sensors for producing an alarm signal when one of said sensors is opened or shorted, said electronic device comprising: a. a bistable multivibrator means connected in said closed-loop having a first normal state representing that said closed-loop circuit is neither open nor short circuited and a second state representing that said circuit is either short or open circuited, said multivibrator means adapted to provide as said alarm signal an output signal representative of said second state and including first and second cross-coupled transistors, said first transistor being in a conducting state during said multivibrator first normal state; b. a source of potential; c. a unidirectional conducting device connected between a point on said closed-loop circuit and to the base of said first transistor, said unidirectional conducting device being in a non-conducting state when the potential with respect to ground of said point on said circuit is at a normal level; d. potential dividing means connected between said source of potential and said point; and e. a switching transistor having a base coupled to said potential dividing means and having collector and emitter leads coupled in series between said source of potential and the base of said first transistor, the normal potential at said point causing said switching transistor to conduct to provide current to the base of said first transistor; said unidirectional conducting device switching to a conducting state to divert current from the base of said first transistor in response to said closed-loop becoming short circuited and said switching transistor switching to a nonconducting state to block current flow to the base of said first transistor in response to said closed-loop becoming open circuited, said multivibrator means switching to said second state to produce said alarm signal whenever the base current flow of said first transistor is diverted or blocked.
Claim 3
Dependent Claim
98 words
characteristic security breach signal producing means connected to said source switch means for activating said signal producing means when said alarm signal is present said signal producing means comprising: saw tooth generator means for generating a saw tooth voltage signal; tone generating means coupled to said saw tooth generator for producing an output, the frequency of which varies in response to the amplitude of said saw tooth voltage signal; and sound generating means coupled to said tone generating means for producing as a said characteristic security breach indication a warbling tone in response to said varying frequency output.
Claim 4
Dependent Claim
98 words
characteristic security breach signal producing means connected to said source switch means for activating said signal producing means when said alarm signal is present said signal producing means comprising: saw tooth generator means for generating a saw tooth voltage signal; tone generating means coupled to said saw tooth generator for producing an output, the frequency of which varies in response to the amplitude of said saw tooth voltage signal; and sound generating means coupled to said tone generating means for producing as a said characteristic security breach indication a warbling tone in response to said varying frequency output.
Claim 5
Dependent Claim
231 words
An electronic security system for detecting breach in security within a closed-loop circuit having at least one sensor which may short said closed-loop in response to a said breach comprising: a bistable multivibrator means coupled to said closed-loop circuit and having a first normal state representing that said circuit is not short circuited and a second state representing that said circuit is short circuited, said multivibrator means adapted to provide an output alarm signal representative of said second state; a first bistable switching means coupled to said closed-loop circuit having a first normal level in which said first bistable switching means remains so long as said closed-loop circuit is closed, and switching to a second level in response to sensing an open-loop, and producing a system malfunction signal when switched to said second level; and a second bistable switching means coupled to said closed-loop circuit having a first normal mode in which said second bistable switching means remains so long as said closed-loop circuit remains closed, and said second bistable means switching to a second mode in response to said closed-loop circuit shorting to ground and producing said system malfunction signal when switched to said second mode; and wherein said first and second bistable switching means are coupled to said bistable multivibrator means for preventing production of said output alarm signal when either a second level or second mode is produced.
Claim 6
Dependent Claim
231 words
An electronic security system for detecting breach in security within a closed-loop circuit having at least one sensor which may short said closed-loop in response to a said breach comprising: a bistable multivibrator means coupled to said closed-loop circuit and having a first normal state representing that said circuit is not short circuited and a second state representing that said circuit is short circuited, said multivibrator means adapted to provide an output alarm signal representative of said second state; a first bistable switching means coupled to said closed-loop circuit having a first normal level in which said first bistable switching means remains so long as said closed-loop circuit is closed, and switching to a second level in response to sensing an open-loop, and producing a system malfunction signal when switched to said second level; and a second bistable switching means coupled to said closed-loop circuit having a first normal mode in which said second bistable switching means remains so long as said closed-loop circuit remains closed, and said second bistable means switching to a second mode in response to said closed-loop circuit shorting to ground and producing said system malfunction signal when switched to said second mode; and wherein said first and second bistable switching means are coupled to said bistable multivibrator means for preventing production of said output alarm signal when either a second level or second mode is produced.
Claim 7
Dependent Claim
45 words
An electronic security system according to claim 2 further comprising: supervision means coupled to said first and second switching means and responsive to the presence of said system malfunction signal therefrom to produce sensible indications for supervisory and maintenance personnel that said system is malfunctioning.
Claim 8
Dependent Claim
193 words
An electronic device for detecting abnormal conditions in a closed-loop circuit, which circuit comprises a first portion normally at a substantially uniform first potential and a second portion normally at a substantially uniform second potential different from said first potential and other than zero, comprising: a. first means for sensing a change in potential at a point on said first portion of the loop produced when said first and second portions become substantially short circuited, for switching from a normal state to an alarm state in response to said change and for providing an alarm signal when switched to said alarm state; b. second means for sensing a change in potential at a point on said first portion of the loop produced when the potential at said point rises above that of said substantially uniform first potential, and for providing an output signal in response to said sensed change in potential; and c. third means for sensing a change in potential at a point on said second portion of the loop portion produced when said potential becomes approximately zero, and for providing an output signal in response to said sensed change in potential.
Claim 9
Dependent Claim
193 words
An electronic device for detecting abnormal conditions in a closed-loop circuit, which circuit comprises a first portion normally at a substantially uniform first potential and a second portion normally at a substantially uniform second potential different from said first potential and other than zero, comprising: a. first means for sensing a change in potential at a point on said first portion of the loop produced when said first and second portions become substantially short circuited, for switching from a normal state to an alarm state in response to said change and for providing an alarm signal when switched to said alarm state; b. second means for sensing a change in potential at a point on said first portion of the loop produced when the potential at said point rises above that of said substantially uniform first potential, and for providing an output signal in response to said sensed change in potential; and c. third means for sensing a change in potential at a point on said second portion of the loop portion produced when said potential becomes approximately zero, and for providing an output signal in response to said sensed change in potential.
Claim 10
Dependent Claim
43 words
An electronic device according to claim 4, wherein said third means is further coupled to said first means to prevent said first means from switching to said alarm state when said third means switches to said second state and produces said output signal.
Claim 11
Dependent Claim
41 words
An electronic device according to claim 4, further comprising an inhibiting means coupled to said first means for holding said first means in said alarm state until a reset signal causes said first means to switch back to said normal state.
Claim 12
Dependent Claim
93 words
An electronic device according to claim 4, wherein said firSt means comprises a bistable multivibrator having a pair of cross-coupled transistors, including a first transistor normally residing in a conducting state and having a base lead coupled to a point on said first closed-loop portion, the normal potential at said point providing current flow through said base lead to maintain said first transistor in a conducting state but the potential at said point, when at the same potential as the potential of said second portion, switching said first transistor to the nonconducting state.
Claim 13
Dependent Claim
121 words
An electronic device according to claim 7, wherein said third means comprises a switching transistor having its collector and emitter leads connected in series with a current source, having its collector lead also connected to said first multivibrator transistor base lead, and having its base lead connected to a point on said second portion of said closed loop, the normal potential of said second portion maintaining said switching transistor in a conducting state and an abnormally low potential at said second portion causing said switching transistor to switch to a nonconducting state, to divert current normally flowing through said switching transistor to said base lead of said first multivibrator transistor to prevent said multivibrator transistor from switching to a nonconducting state.
Claim 14
Dependent Claim
72 words
An electrical device according to claim 4, wherein said second means comprises a switching transistor having its collector and emitter leads connected in series with a current source and having its base lead coupled to said point in said first portion of said closed-loop circuit so as to be in a normally conducting state but turning off in response to an increase in potential at said point to provide an output signal.
Claim 15
Dependent Claim
257 words
A limited current drain device coupled to a closed-loop circuit for providing a momentary indication indicative of a closed circuit condition existing in said closed-loop circuit comprising: a. energy source means; b. switch means having first and second normally closed switches mechanically coupled to operate together as a unit, said first switch connected in series to said closed-loop circuit; c. a series circuit connected to said energy source including a current limiting resistor having one end connected to said energy source, a normally open switch means, a light indicating means and said second normally closed switch, the current flow from said energy source means through said series circuit when completed by closure of said normally opened switch means causing a limited current drain on said energy source; d. a capacitor; e. a switching circuit means connected across said current limiting resistor and to said capacitor, said switching circuit means connecting said capacitor to said energy source when said normally open switching means is open to charge said capacitor, said switching circuit means connecting said capacitor to said other end of said current limiting resistor when said normally open switch means is operated to the closed position and said second normally closed switch is closed, to provide a discharge path for said capacitor, said light indicating means providing a momentary indication in response to current flow produced by said discharge of said capacitor, said momentary indication being indicative of the position of said switch means and therefore indicative of a closed circuit condition existing in said closed-loop circuit.
Claim 16
Dependent Claim
257 words
A limited current drain device coupled to a closed-loop circuit for providing a momentary indication indicative of a closed circuit condition existing in said closed-loop circuit comprising: a. energy source means; b. switch means having first and second normally closed switches mechanically coupled to operate together as a unit, said first switch connected in series to said closed-loop circuit; c. a series circuit connected to said energy source including a current limiting resistor having one end connected to said energy source, a normally open switch means, a light indicating means and said second normally closed switch, the current flow from said energy source means through said series circuit when completed by closure of said normally opened switch means causing a limited current drain on said energy source; d. a capacitor; e. a switching circuit means connected across said current limiting resistor and to said capacitor, said switching circuit means connecting said capacitor to said energy source when said normally open switching means is open to charge said capacitor, said switching circuit means connecting said capacitor to said other end of said current limiting resistor when said normally open switch means is operated to the closed position and said second normally closed switch is closed, to provide a discharge path for said capacitor, said light indicating means providing a momentary indication in response to current flow produced by said discharge of said capacitor, said momentary indication being indicative of the position of said switch means and therefore indicative of a closed circuit condition existing in said closed-loop circuit.
Claim 17
Dependent Claim
135 words
A limited current drain device according to claim 10 wherein said switching circuit means comprises a first transistor having emitter and collector leads connected across said current limiting resistor, having a base lead connected to said capacitor and having a conduction state controlled by said capacitor, and a second transistor having its emitter and collector leads connected in series between said energy source and said capacitor and having its base coupled to the emitter of said first transistor; said second transistor conducting to rapidly charge said capAcitor when said normally open switch means is in its open state and said capacitor when charged causing said first transistor to momentarily conduct to pass current from said capacitor to said lamp when said normally open switch means is closed and said second normally closed switch is closed.
Claim 18
Dependent Claim
87 words
An electronic security system for indicating breaches in security within at least one closed-loop circuit comprising: a. sensing means for sensing breaches in security in said at least one closed-loop circuit; b. at least one alarm signal producing means coupled to said sensing means for producing an alarm signal and response to said sensing; and c. indicating means coupled to said at least one alarm signal producing means for producing a characteristic security breach indication in response to a said alarm signal, wherein said indicating means comprises:
Claim 19
Dependent Claim
87 words
An electronic security system for indicating breaches in security within at least one closed-loop circuit comprising: a. sensing means for sensing breaches in security in said at least one closed-loop circuit; b. at least one alarm signal producing means coupled to said sensing means for producing an alarm signal and response to said sensing; and c. indicating means coupled to said at least one alarm signal producing means for producing a characteristic security breach indication in response to a said alarm signal, wherein said indicating means comprises:
Claim 20
Dependent Claim
192 words
An electronic security system according to claim 12 wherein each of said at least one closed-loop circuit has associated therewith at least one sensing means and wherein the sensing means associated with each closed-loop circuit is coupled to a separate alarm signal producing means, wherein a first of said alarm signal producing means is capable of producing a first alarm signal, and a second of said alarm signal producing means is capable of producing a second alarm signal; and wherein said source switch means further comprises means responsive to said second alarm signal to deactivate said tone generator, and wherein said characteristic signal producing means further comprises a free running multivibrator means for producing a series of pulses, which multivibrator is capable of being activated by said switching means in response to said second alarm signal, and wherein said multivibrator is coupled to said tone generator such that said series of pulses is transformed into a series of intermittent burst of signals having a characteristic frequency within each burst to produce an intermittent tone in said sound generating means as said characteristic security breach indication when said second alarm signal is present.
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) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |