US3794991A

US3794991A - Alarm system with timed exit circuit means

Info

Publication number: US3794991A
Application number: US00224186A
Authority: US
Inventors: L Guthart
Original assignee: Alarm Device Manufacturing Co
Current assignee: Alarm Device Manufacturing Co
Priority date: 1972-02-07
Filing date: 1972-02-07
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26

Abstract

An intruder-activated alarm system operating pursuant to the McCullough loop principle. The system includes a protected circuit incorporating an exit means-controlled switch. Arming means for the protected circuit includes a delay circuit for suspending activation of the protected circuit for a predetermined period. Subsequent to such period, opening and closing of said exit means-controlled switch causes a motor to successively cycle and drive a coded transmitter which sends two rounds of signals to a central office. Subsequent disruption of the protected circuit causes further operation of said motor, which in turn effects transmission of alarm signals to said central office.

Description

United States Patent Guthart 1 Feb. 26, 1974 1 1 ALARM SYSTEM WITH TIME!) EXIT 3,510,863 5/1970 MCBI'IUI] 340/276 3,286,250 11/1966 'Icilclhaum 1. 340/276 CIRCUIT MEANS Primary Examiner-John W. Caldwell Assistant ExaminerScott F. Partridge Attorney, Agent, or Firm-Sommers & Sommers [57] ABSTRACT An intruder-activated alarm system operating pursu ant to the McCullough loop principle. The system includes a protected circuit incorporating an exit meanscontrolled switch. Arming means for the protected circuit includes a delay circuit for suspending activation of the protected circuit for a predetermined period. Subsequent to such period, opening and closing of said exit means-controlled switch causes a motor to successively cycle and drive a coded transmitter which sends two rounds of signals to a central office, Subsequent disruption of the protected circuit causes further operation of said motor, which in turn effects transmission of alarm signals to said central office.

7 Claims, 2 Drawing Figures [75] Inventor: Leo (Iulharl, ()ld Wcsthury, NY.

[73] Assignee: AIa rm Device Manufacturing W Company, a division of Pittway Corporation, Syosset, NY.

[22] Filed: Feb. 7, 1972 [21] Appl. No.: 224,186

[52] US. Cl. 340/409, 340/276 [51] Int. Cl. G08b 13/08, G08b 29/00 [58] Field of Search... 340/274, 276, 293, 215, 309, 340/409, 214

[56] References Cited UNITED STATES PATENTS 3,484,771 12/1969 Falck 340/215 X 3,534,350 10/1970 Sellinger... 340/276 X 3,548,401 12/1970 Guthart i 340/276 X 2,783,462 2/1957 Chase i i i 1 340/276 3,636,546 1/1972 Lomonaco 340/276 TRANSMITTER ALARM SYSTEM WITH TIMED EXIT CIRCUIT MEANS BACKGROUND OF INVENTION This invention relates generally to intruder-activated alarm systems, and more specifically relates to central station alarm systems operating on the McCullough loop principle.

In US. Pat. No. 3,548,401, issued on Dec. 15, 1970, to Leo A. Guthart, which patent is assigned to the assignee of the instant application, a highly effective alarm system is disclosed operating on the so-called McCullough loop principle. Pursuant to this principle a plurality of subscribers share a common telephone line (or a radio frequency band or the like) and are differentiated by the nature of the code transmitted at the subscribers station. The said patent in particular, disclosed a system wherein simplification in supervisory functions is enabled via use of an arrangement wherein an exit means controlled switch activates a motor for driving a coded transmitter which provides signals to the central office. In accordance with said disclosure a subscriber initially arms the system, and then proceeds to leave the premises. When the exit door of the premises is opened one round of information is transmitted to the central office; when the said door is closed a second round of information is transmitted; subsequently interruptions in the protected circuit e.g., by opening protected windows, doors or the like will transmit three rounds of signals to the central office, thereby presumably signaling entry of an intruder into the protected zone.

Unfortunately the system as set forth in the prior paragraph, has in some instances functioned in a less than ideal fashion. In particular with certain installations, there is a possibility that an error can occur as the proprietor of the premises walks toward the exit door following the initial arming of the alarm system. Such accident during closing can occur if interior protection devices like photoelectric beams or motion detectors are used. Once a subscriber arms a system thus provided, a closing signal is sent to the central station the very next time that the protective circuit is interrupted. If, accordingly, the subscriber should accidentally interrupt a photoelectric or motion detector on his way out, there is a possibility that the two closing rounds will be sent at that time. When the subscriber finally then reaches the door, the transmitter will interpret that as an alarm signal, rather than a closing signal. The net result of the accidental disturbance is that the subscriber has left the premises and the system has already reported a closing and an alarm, and is no longer armed. This means that the alarm company must come to the premises and reset the unit. Aside from the obvious inefficiency and costs involved in such resetting operations, it may be observed that false alarms of this type tend to impair confidence in the alarm system and act as a psychological deterrent to effective use thereof.

In an effort to eliminate the aforesaid problem, various schemes have in the past been proposed, intended to delay sending of signals subsequent to arming of the alarm. These have commonly taken the form of relatively crude mechanical delay mechanisms placed directly onto the protection devices themselves. For example. an installation company might place a time delay on a motion detector in an attempt to hold out from the transmitter any interruptions of the motion detector. This type of delay, however, is unsupervised and runs the risk that the delay will stay on and the motion detector will be inoperative for the entire night.

In accordance with the foregoing, it may be regarded as an object of the present invention, to provide an intruder-activated alarm system operating on the McCullough loop principle, which includes features preventing accidental sending of alarm signals during the closing operation.

It is a further object of the invention, to provide an intruder-activated alarm system of the McCullough type, wherein arming of the system may be followed for a limited period by any number of accidental disruptions of the protected circuit without-causing the send ing of closing signals, whereby accidental indication of an alarm condition is prevented during the closing operation.

It is an additional object of the invention, to provide an intruder-activated alarm system of the McCullough variety, including dependable electrical means for delaying sending of closing or alarm signals following arming of the system, which means, further, act to alert the central station should the subscriber not close in a proper manner.

SUMMARY OF INVENTION Now in accordance with the present invention, the foregoing objects, and others as will become apparent in the course of the ensuing specification, are achieved by incorporating a timed exit circuit into the arrangement set forth in the Guthart patent previously alluded to. The said circuit functions in combination with the basic system as to prevent subscribers from sending accidental closing signals on their way out from the protected premises at the end of the day. In particular the circuit acts to place a hold of approximately 60 seconds on the protective circuit once the transmitter is armed. During this hold period the subscriber can disturb the protective circuit any number of times and no closing signals will be sent. At the end of the 60 seconds hold, if the protective circuit is closed and there has been at least one opening and closing during the period, two consecutive closing rounds will be sent. On the other hand, if the protective circuit is left open at the end of the 60 seconds, only one round will be sent, alerting the central station that the subscriber has not closed properly. An intrusion or re-entry will cause a three round alarm signal with no delay.

BRIEF DESCRIPTION OF DRAWING The invention is diagrammatically illustrated, by way of example, in the drawing appended hereto, wherein similar reference characters indicate like parts, in which:

FIGS. 1 and 2 taken together are a schematic diagram of a circuit in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENT In FIGS. 1 and 2 a schematic diagram appears, setting forth an alarm system in accordance with the present invention. The system is seen to include generally a protected circuit 3 (FIG. 2) and an alarm circuit 5 (FIG. 1). Terminals 7, 9, l1 and 13 are common to the circuits 3 and 5 whereby, as will be seen, various functions are enabled, depending upon the position of movable contact 15. Thus when contact 15 overlies terminal 7 the circuit 1 is in an on" state; similarly at terminal 9 the circuit is in a test" position; at terminal 11, in a bell test position; and at terminal 13 the circuit is of Protected circuit 3 is seen to include a pair of

terminals

17, 19 which are connected to a supervisory battery, not explicitly shown. In series therewith are the coil 21 for a solonoid switch 23 located in alarm circuit 5, an ammeter 25, and access controlled switches 27, 29. The latter two elements are taken to be two in number merely by way of example. In practice a larger number of such switches could be so utilized. It may furthermore, for purposes of illustration, be assumed that switch 27 is a normally closed window operated unit, and switch 29 a normally closed switch that is opened upon opening of the door to the premises sought to be protected.

Alarm circuit is seen to be centered upon an electric motor 31 of conventional design, which for each revolution drives a transmitter 33, also conventional. For each revolution of the said motor transmitter 33 sends out a coded message, which may be transmitted by land lines, telephone, radio link or so forth, to a central monitoring station. Such facet of the invention is wcllknown in the art and need not be further described herein.

Motor 31 also drives a switch. in a preferred form of the invention, the switch is an intermittently driven wafer stepping switch 35 driven from the motor 31 by reduction gearing or the like. The switch and motor arrangement is essentially identical to similar elements disclosed in the aforementioned Guthart patent. Switch 35 is provided with contacts equally spaced apart circumferentially, and a rotor 37 having an arcuate lobe 39 of an extentjust short of spanning any two adjacent contacts. For purposes of description each contact in the Figure is provided with a number designation running serially from 1 to 10. The normal rest position of switch 35 is, as shown, with the lobe 39 midway of contact 1. The lobe 39 is at all times connected to a wiper at 41.

In order to understand the operation of the present system, let it be assumed that initially the system is activated or armed" by placing arm in the on position, that is by moving arm 15 to a position upon contact 7. Under such conditions coil 21 carries current and in consequence switch 23 is placed in the on position shown in the Figure by the dotted line 43', wherein the arm 43 of such switch electrically engages contact 46. At the same time it will be seen that with contact 7 closed in the alarm circuit 5, the solonoid coil 47 is series therewith is connected to the positive side 49 of a battery 51 in the said circuit; in consequence arm 53 associated with coil 47 is displaced to the closed position shown wherein it engages contact 55; the return circuit from coil 47 includes diode 48, lead 57, contact 7, lead 59, thence contact 1 lobe 39 and contact 6 at switch 35, and lead 61 back to the negative side 63 of battery 51.

Under the conditions set forth above negative terminal 63 of battery 51 is also coupled through contact 55, diode D1 and lead 67 to the gate circuit of SCR 73. SCR 73 is normally non-conductive but upon firing will provide a conductive path through leads 75 and 77 to one side 79 of motor 31, thereby enabling motor 31 upon application of a potential to its alternate lead 81.

Regarding now terminal 81 of motor 31, it will be appreciated that positive terminal 49 of battery 51 is connected to such terminal via lead 81 and thence via depending upon the position of arm 83 one of two routes. With arm 83 contacting point 85, as shown, the route is through resistor 87 and diode 89 and thence the pair of

transistors

91, 93, the output from the latter proceeding via lead 95 to terminal 81. This route for enablement of motor 31 is a delay route, the time delay depending specifically upon the values of resistor 87 and capacitor 97, but generally being about 60 seconds. Alternatively it will be noted that the arm 83 may be positioned on contact 86 in which case no delay in enablement of motor 81 occurs.

Assume that at some time during the timing out of the 60 second delay period, switch 23 is opened and closed, i.e., that arm 43 is displaced back and forth from its dotted line position. Upon such occuring a pulse is coupled from capacitor through

resistors

69, 68, and capacitor 71 to the gate circuit of SCR 73, firing the latter to conduction. A path is thereby enabled through SCR 73, leads and 77, to one side 79 of motor 31. Assuming therefore that arm 83 is in its delay position it will be clear that a potential is applied to the motor at the end of the delay period. The motor 31 then moves rotor 37 from contact I to 2 and a round of signals is sent as transmitter 33 is activated. Upon lobe 39 reaching contact 3, it is seen that terminal 79 of the motor is still in electrical contact with the negative side of battery 51, now via lead 99 from contact 2; thus a second round of signals is immediately sent from transmitter 33, after which the rotor comes to rest with lobe 39 resting on contact 3. Since arm 23 is in its lower position i.e., upon contact 46, no further movement of rotor 37 ensues. It will further be evident that thereafter, if intrusion, say at door switch 29 (or other access-controlled switch such as switch 27) occurs, arm 43 is displaced to contact 45, whereupon lobe 39 activates motor 31 through the connection of lead 75. The lobe 39 thence is displaced to contact 4, which is still connected (by lead 99) to motor 31, whereupon a second round of signals is sent; finally lobe 39 is displaced from contact 5 in consequence of the conductive path through lead 101, SCR 73 and lead 75 and a third round of signals is thereby provided from transmitter 33.

Let it be supposed that, as sometimes happens, a closing is improperly effected as the proprietor departs from the protected premises. Under such conditions arm 43 is left in an open position, that is upon contact 45. Upon such occuring it will clear that the lobe 37 will only rotate so far as contact 2, since contact 3 can effect no conductive path via arm 43. Therefore only one round of signals is generated by transmitter 33, in consequence of which it is made known to the central monitoring station that an improper closing has occurred at the premises.

In order to provide a local indicator of alarm conditions, it is seen that a bell 109 is provided. One side of bell 109 is connected to terminal 111 and thus to positive terminal 49 of battery 51. The other side of the bell is connected to a terminal 113 and thence via lead 115 to contact 117. As soon as current in coil 47 is disrupted for any reason, arm 53 moves to contact 117, and upon lobe 39 reaching contact 1, the local bell alarm is sounded.

' pended hereto.

I claim: 1. An intruder-activated alarm system for premises, comprising in combination:

a. a protected circuit and an alarm circuit at said premises;

b. a code transmitter;

c. a motor for driving said transmitter;

d. a switching system contained in said protected circuit, said system including an exit means controlled switch;

e. arming means, for activating said circuits;

f. power supply means for said system;

g. delay means for suspending activation of said alarm circuit for a predetermined period following arming thereof, comprising a delay circuit interposed between said power supply means and a first side of said motor, said delay circuit being responsive to said arming by delaying application of potential to said motor for said predetermined period;

h. means initiated upon an opening and closing of said exit means controlled switch during said predetermined delay period, to enable a potential to the second side of said motor to operate said transmitter for a predetermined operation after running of said delay period, whereby to provide a signal indicative of proper closing by authorized persons 6 departing said premises; and

i. means operated upon subsequent opening of said protected circuit to further operate said motor and said transmitter for a predetermined operation, to provide an alarm indication.

2. A system in accordance with claim 1, wherein said delay circuit comprises a pair of normally nonconductive transistor switches activated by an RC delay circuit.

3. A system in accordance with claim 1, further in-' cluding means to selectively shunt said delay circuit, whereby said system may optionally be operated without delay following arming thereof.

4. A system in accordance with claim 1, further including means operable upon said access-operated switch being left in an open condition following said delay period, to activate said transmitter for a predetermined operation, whereby signals indicative of a faulty closing at said premises are sent to a monitoring point.

5. A system in accordance with claim 1, wherein said means causing said motor to operate upon opening and closing of said access-operated switch during said delay period, includes a normally non-conductive SCR connected between one terminal of said motor and said power supply, the gate circuit of said SCR being connected to fire said SCR to conduction upon said opening and closing operation.

6. A system in accordance with claim 4, further including local alarm means and means to activate said local alarm means upon opening of said protected circuit subsequent to said delay period.

7. A system in accordance with claim 5, further including selectively activatable circuit means for testing said local alarm and protected circuits.

Claims

1. An intruder-activated alarm system for premises, comprising in combination: a. a protected circuit and an alarm circuit at said premises; b. a code transmitter; c. a motor for driving said transmitter; d. a switching system contained in said protected circuit, said system including an exit means controlled switch; e. arming means, for activating said circuits; f. power supply means for said system; g. delay means for suspending activation of said alarm circuit for a predetermineD period following arming thereof, comprising a delay circuit interposed between said power supply means and a first side of said motor, said delay circuit being responsive to said arming by delaying application of potential to said motor for said predetermined period; h. means initiated upon an opening and closing of said exit means controlled switch during said predetermined delay period, to enable a potential to the second side of said motor to operate said transmitter for a predetermined operation after running of said delay period, whereby to provide a signal indicative of proper closing by authorized persons departing said premises; and i. means operated upon subsequent opening of said protected circuit to further operate said motor and said transmitter for a predetermined operation, to provide an alarm indication.

2. A system in accordance with claim 1, wherein said delay circuit comprises a pair of normally non-conductive transistor switches activated by an RC delay circuit.

3. A system in accordance with claim 1, further including means to selectively shunt said delay circuit, whereby said system may optionally be operated without delay following arming thereof.