US3340521A

US3340521A - Alarm system

Info

Publication number: US3340521A
Application number: US369232A
Authority: US
Inventors: Jr Jesse L Patterson; William R Quinn; Earl R Quinn
Original assignee: Automatic Sprinkler Corp
Current assignee: Automatic Sprinkler Corp
Priority date: 1964-05-21
Filing date: 1964-05-21
Publication date: 1967-09-05
Anticipated expiration: 1984-09-05

Description

United States Patent 3,340,521 ALARM SYSTEM Jesse L. Patterson, Jr., William R. Quinn, and Earl R.

Quinn, Houston, Tex., assignors, by mesne assignments,

to Automatic Sprinkler Corporation of America, Houston, Tex., a corporation of Ohio Filed May 21, 1964, Ser. No. 369,232 5 Claims. (Cl. 340258) This invention relates to alarm systems, particularly of the type which may be installed in institutions or other large buildings for causing an alarm responsive to the presence of an intruder.

Most intruderfalarm systems, for instance, those energized by the opening of a window or a door, are subject to malfunctioning or to being tricked. Where the alarm is sound sensitive, it may be energized by sounds not caused by an intruder. Accordingly, there is need for a reliable intruder alarm system which will be energized to give an alarm, with reasonable certainty, only when an intruder is present.

Accordingly, an object of the present invention is to provide a novel intruder alarm system with such safety features as to render the alarm substantially inoperable by occasional or expected sounds.

Another object is to provide a sound-sensitive alarm system including means for preventing the operation of the alarm device whenexpected sounds are produced in the monitored region, for instance, the striking of a clock or the like. V 7

Another object is to provide a sound-sensitive alarm system which is not energized by occasional random sounds.

In accordance with the present invention, there is provided an alarm system which incorporates any number of microphones located in the vicinity of regions to be protected and circuits connecting the microphones through suitable amplifiers with an audible or other alarm device. One or more additional microphones are located. near expected sounds and connected into the circuitry in such a way as to prevent the giving of a signal responsive to such sounds. Furthermore, the circuitry includes repeater means whereby a sound must be repeated. a predetermined number of times within a definite time interval, as characteristic of sounds produced by an intruder, in order to set otlf the alarm.

Finally, the microphones or other circuitry may be desensitized to sounds of certain quality, for instance, road noises.

In the accompanying drawing which illustrates the invention the figure is a diagrammatic representation of exemplary circuitry used.

In the figure, there are shown four monitoring microphones 5, 6, 7, and 8, although any number may be provided, which are located in the areas to be protected. All of these microphones are connected through resistances 9, 10, 11, and 12 and acondenser 13 to amplification stage A including a transistor 15 and

thermionic tubes

16, 17, and 18, resistances and capaci tances being interposed in the amplifier circuit in conventional manner as shown. Electrical energy for the transistor is supplied through wires 19-23 inclusive. The anodes of

tubes

16, 17, and 18 are connected through

wires

24, 25, 26, and 27 to positive DC. power line 28, in turn connected through diode rectifier 29 to secondary 30 of transformer 31. The anode of tube 18, also, is connected through a condenser 33 and a full-wave rectifier, including diodes 34 and 35 and thence to the grid of a tube 36. The cathodes of tubes 16 and 17 are grounded.

The winding of a relay B is connected by a wire 39 to the cathode of tube 36 so as to function as a cathode :follower, responsive to an excitation of one of the microphones 5, 6, 7, or 8. Relay B has a normally open contact B-l which is grounded and thereby serves to shunt the relay winding through resistance 37 to eliminate or reduce the differential normally existent between the relay energizing and de-energizing voltages. Normally open relay contact B-2 is connected by a wire 40 through the winding of a relay C to a power source 41 controlled by two pole switch 42. Relay pole contact B-2 connects via a wire 43 to the other main power line 44. Relay C has a double throw contact pole C-1 and a pair of contacts 45 and 46. Pole C1 connects through a condenser 47 to ground. Relay contact 45 is connected by

wires

48 and 49 to a positive DC. power source, including transformer secondary 30, a diode rectifier 29, and a resistance 51. The other end of secondary 30 is connected to ground across the normally open contacts 52 of a thermal switch D, the heater 53 of which is connected across A.C. power lines 41 and 44.

The other contact 46 of relay C is connected by a wire 56 and resistance 57 to a condenser 58 and also through a wire 59 to a condenser 60 and a wire 61 to a neon bulb 62. A high ohmage resistance 63 shunts condenser 60 and bulb 62. Wires 59 and 61 and resistance 63 are grounded at 64. Wire 56 is also grounded through a shock absorber condenser 65 and is connected by a wire 68 through a diode rectifier 69 to the normally open contact 70 of a relay E. Previously mentioned condenser 58 is connected by a wire 71 to the grid of a thermionic tube 72. The cathode of tube 72 is grounded at 73, While the anode of this tube is connected by a wire 74 through a condenser 75 to the grid of a tube 76. The winding of relay E is connected to the cathode of tube 76, as a cathode follower, while the anode of tube 76 is connected by a wire 77 to the positive D.C. line 28.

The heater unit of a thermal switch F is connected, during operation by wires 80 and 81 across D.C. positive line 28 through contact of relay E and wire 68 leading to contact 46 of relay C. The contact 83 of thermal switch F connects ground through wires 84 and 85 to wire 86 connecting condenser 75 to the grid of tube 76.

Relay E has two double-throw contact poles E1 and 13-2. Relay pole E-1 is grounded at 87. Normally closed relay contact 88 is connected by a wire 89 to the cathode of amplifier tube 18 so as to normally enable the amplifier. Normally open relay contact 70, previously mentioned, grounds wire 68 leading through diode 69 and resistance 57 from previously mentioned contact 46 of relay C. Normally closed relay contact 91, associated with relay contact pole E-2, which is connected to ground, closes a circuit through wire 92, which is connected to ground, and wire 93 for energizing an all clear signal 94. Normally open contact 95, also associated with relay pole contact E-2, serves through

wires

92 and 96 to energize an alarm, as an audible alarm 97, this being responsive, as will be explained, to an intruder created signal.

The remainder of the circuit is for the purpose of preventing expected sounds from energizing the alarm. At

100 is represented a microphone which would be positioned in the vicinity of an expected sound, as a striking clock, mechanical refrigerator, or the like. This microphone is connected by a wire 101 and condenser 102 through three-

stage amplification tubes

103, 104, and 105 to a full-wave rectifier, including

diodes

106 and 107 with shunting condenser 108 and resistance 109. The anodes of the tubes are connected, respectively, by wires 110115, inclusive, to positive D.C. line 28. The cathodes of these tubes are provided with grounds and grid leak resistances, as shown. A wire 116 connects full-

wave rectifier

106, 107 to wire 117 connecting full-wave rectifier 34, 35 to the grid of tube 36. The purpose of this circuitry, as will be explained, is to cancel out a signal impressed on cancellation microphone 100 and also transmitted through one of the alarm microphones 5, 6, 7, or 8. Wire 101 is also connected by a wire 118 including resistance 119 to negative potential source wire 19.

The apparatus operates as follows: When the system is monitoring normally and under conditions when no alarm should be given, normally closed E relay contact 88 may be used to energize a signal, for instance, a bulb 94, to indicate that everything is in order. Now, in case an energizing sound is picked up by one of the alarm microphones 5, 6, 7, or 8, but not by cancellation microphone 100, the resultant energy will be amplified by means A, rectified by diodes 34 and 35, and applied as a positive pulse to the grid of tube 36. Tube 36, then, will become conducting causing energization of the winding of cathode follower relay B, which through normally open relay contacts B-2 will energize the winding of relay C. Relay pole C1,, normally, engages contact 45 which directs a charge from transformer secondary 30 and

wires

49 and 48 upon condenser 47. Upon the switching of relay pole C-1 into engagement with contact 46, condenser 47 will be discharged into condensers 58 and 60. The capacity of condenser 47 is very much smaller than that of condensers 58 and 60 so that several pulses from condenser 47 are necessary to fully charge condensers 58 and 60. Conveniently, condenser 47 may be of .15 microfarads capacity and condensers 58 and 60 of sufficient capacity that about five discharges from condenser 47 and, consequently, five signal pulses from the alarm microphones, are necessary to fully charge condensers 58 and 60. Of course, condenser 47 is recharged each time relay pole C-l returns to normally closed contact 45. When the charge on capacitors S8 and 60 reaches approximately 70 volts, neon lamp 62 fires, discharging condensers 58 and 60, generating a negative pulse on the grid of tube 72. The accumulated charges on condensers 58 and 60 may leak off through resistance 63, in an exemplary embodiment of the value 22,000,000 ohms, so that the impulses from condenser 47 necessary to fully charge condensers 58 and 60 must occur within a predetermined time interval. The reason for this is that it is characteristic of an intruder that the noises caused will be repeated and, thus, random and other noises not repeated sufficiently within the predetermined time interval will not set 011 the alarm because, in the intervening time, condensers 58 and 60 may discharge through resistance 63.

The discharge of condensers 58 and 60, as explained, has the effect of rendering the grid of tube 72 more negative, and, therefore, the anode of this tube becomes more positive, causing a positive pulse to be supplied through line 74, resistors 120, 121, and 122, and wire 86 to the grid of tube 76. This then energizes the cathode following winding of relay E causing its pole contacts 13-1 and E-2 to reverse. Such reversal of pole E1 connects relay contact 70 to ground to complete the discharge of condensers 58 and 60. The reversal of relay pole E-2 energizes contact 95 and wire 93 to produce a signal, as through the audio device 97. Shifting of relay contact E-l, as stated, causes supply of positive energy to the grid of tube 76, through wire 80, the heater of thermal relay F, resistances 121 and 122 and wire 86, in efiect, latching relay E in alarm condition. However, contacts 83 of this thermal relay will close after a predetermined interval, grounding the grid of tube 76 and unlatching relay E to stop the alarm. The same effect may be achieved, to stop the alarm signal, by closing reset button 123 or by closing a key switch 124.

In case of a sound which is monitored by the cancellation microphone 100, the amplified energy resultant therefrom is converted into a negative pulse by

diodes

106 and 107 and fed through wire 116 whence it is added algebraically to the positive pulse generated in wire 117 by the effect of the same sound on one of the alarm microphones. This prevents the energization of cathode follower relay B and the resultant shifting of counting relay pole C-1.

It should be further noted that while contacts E-1 are closed amplifier 18 is disabled and hence the signals detected by microphones 5, 6, 7 and 8 have no effect on the circuit operation.

A secondary winding 125 supplies energy through wire 19 to the filaments of all of the tubes and also to microphones 58 through

wires

21, 22, and 23 and to transistor 15 through a wire 126. At 128 and 129 are shown filter condensers for the power supply.

Various features of the circuitry may be modified as will occur to those skilled in the art. The

wires

92 and 93 controlled by relay pole contact E-2 may be utilized for a purpose other than illuminating a ready lamp, or may serve no purpose in connection with the system. Moreover, the alarm may be tied in with a communication system throughout the building. The invention may be modified in these and other respects as will occur to those skilled in the art, and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In an alarm system, an electric circuit including in series a microphone,

means for converting microphone excitations to electrical energy, and

the first contacts of a double throw switch;

a second circuit including a first condenser,

a source of condenser charging current for charging said condenser through said first switch contacts when said switch is in a first position;

a third circuit including a second condenser,

the other of contacts of said switch, and

an alarm device; means responsive to acoustical excitation of said microphone for shifting said switch from said first to said second position for discharging said first condenser into said second condenser,

the capacity of said second condenser being sufficiently greater than that of said first condenser so that a predetermined number of discharges from said first condenser are required to charge said second condenser to a preselected voltage level; and

circiut means connected to said second condenser for responding to said preselected voltage level to discharge said second condenser and to initiate energization of said alarm device.

2. An alarm system as described in claim 1 further including a resistance connecting said second condenser to ground in a manner to bleed oflf the charge on said second condenser to establish a time interval during which said shifts of said switch must occur in order to energize said alarm device.

3. An alarm system as described in claim 1, further including an amplifier initially activated by the overcharge of said second condenser,

a relay for energizing said alarm device activated by the output from said amplifier,

means for maintaining the activation of said amplifier after its initial activation, and

a thermal switch for disabling said amplifier after a predetermined period.

4. In an alarm system, a first electrical circuit including a microphone,

an amplifier, and

6 the Winding of a relay having a double throw movable responding to said charge of preselected magnitude to contact and first and second contacts for alternative energize said alarm device and to substantially discharge engagement thereby, said winding being activated said second capacitance. by a signal from said amplifier; 5. The combination described in claim 4, further ina second circuit including 5 eluding a resistance for delaying bleed off of said second said movable contact, and capacitance for a predetermined period such that said prea first capacitance operably connected thereto; determined number of charge transfers between said a third circuit including capacitance must occur within a predetermined time insaid first relay contact, and terval to cause energization of said alarm device. a source of condenser charging current for charging said capacitance when said movable contact is in a References Cited f t n i a; 1 d. UNITED STATES PATENTS a o circui mcu mg said second relay contact, g i 340-461 a second capacitance operably connected thereto, and 2329570 9/1943 W an alarm device connected for operation in response 2428290 9/1947 P ekens 340 258 to 'a charge of preselected magnitude on said second 2435996 2 capacitance; and /1948 Band 340-258 an operative connection between said microphone and g 179 1'8 said relay movable contact through said amplifier agnalre' 3 10/1956 Bagno 340258 and said wlndmg for shiftmg said movable contact 2 826 753 11/1958 Ch 340 258 to a second position in engagement with said second apm relay contact in response to acoustical excitation 7012 9/1959 Pltman 340 '261 X 2 925 583 2/1960 Jeffers 34-0-37 of said microphone, thereby transferring the charge 2942247 6/1960 340 261 X on said first capacitance to said second capacitance, 3109165 10/1963 Blenau the capacity of said second capacitance being sutfiagno 8 ciently greater than that of said first capacitance 5/1964 Kelly 340-261 3 155 954 11/ 1-964 Lar-rlck 340-261 so that a predetermined number of charge transfers from said first capacitance to said second capaci- NEIL C. READ, Primary Examiner tance are required to charge said second capacitance to said preselected magnitude; and L TRAFTON, GOLDMAI;

circuit means connected to said second capacitance for Asslsllmf m s-

Claims

1. IN AN ALARM SYSTEM, AN ELECTRIC CIRCUIT INCLUDING IN SERIES A MICROPHONE, MEANS FOR CONVERTING MICROPHONE EXCITATIONS TO ELECTRICAL ENERGY, AND THE FIRST CONTACTS OF A DOUBLE THROW SWITCH; A SECOND CIRCUIT INCLUDING A FIRST CONDENSER, A SOURCE OF CONDENSER CHARGING CURRENT FOR CHARGING SAID CONDENSER THROUGH SAID FIRST SWITCH CONTACTS WHEN SAID SWITCH IS IN A FIRST POSITION; A THIRD CIRCUIT INCLUDING A SECOND CONDENSER, THE OTHER OF CONTACTS OF SAID SWITCH, AND AN ALARM DEVICE; MEANS RESPONSIVE TO ACOUSTICAL EXCITATION OF SAID MICROPHONE FOR SHIFTING SAID SWITCH FROM SAID FIRST TO SAID SECOND POSITION FOR DISCHARGING SAID FIRST CONDENSER INTO SAID SECOND CONDENSER, THE CAPACITY OF SAID SECOND CONDENSER BEING SUFFICIENTLY GREATER THAN THAT OF SAID FIRST CONDENSER SO THAT A PREDETERMINED NUMBER OF DISCHARGES FROM SAID FIRST CONDENSER TO A PRESELECTED VOLTAGE LEVEL; AND OND CONDENSER TO A PRESELECTED VOLTAGE LEVEL; AND CIRCUIT MEANS CONNECTED TO SAID SECOND CONDENSER FOR RESPONDING TO SAID PRESELECTED VOLTAGE LEVEL TO DISCHARGE SAID SECOND CONDENSER AND TO INITIATE ENERGIZATION OF SAID ALARM DEVICE.