US3495040A - Security alarm system - Google Patents

Description

Filed June 9, 1967 R71 mm NJ EN 4% e mc w n m m w L ATTORNEY.

United States Patent Ofifice 3,495,040 Patented Feb. 10, 1970 3,495,040 SECURITY ALARM SYSTEM Lawrence N. Lea, 1683 University Ave., New York, N.Y. 10453 Filed June 9, 1967, Ser. No. 645,002 Int. Cl. H04m 11/00; H031: 17/00 U.S. Cl. 179--2 7 Claims ABSTRACT OF THE DISCLOSURE This system contemplates that the protected area is provided with a telephone whose lines lead to an attended switchboard outside such area. The operator at the switchboard, is given notice that the security system is on, and then again when it is off so he can cease his vigilence. Upon a violation of the protected area, the system shunts the telephone lines as if the receiver has been taken on its hook, so the lamp or annunciator associated with said telephone, is actuated.

The shunting of the lines is accomplished upon the firing of a controlled electronic rectifier of the type having an anode, a cathode and a gate, which latter when subjected to a charge, makes said rectifier conductive so that current is allowed to flow from the anode to the cathode. A bridge rectifier has its input terminals connected to the telephone lines. Its output is applied to said controlled electronic rectifier. Also, a condenser is arranged to be charged by said output and to impose a charge upon said gate when the protected area is violated. A switch is provided in the circuit to set the security alarm system on and ofi. Other condensers are employed for protective purposes, and there is a means to show when the system is on. Telephone service is never interrupted while the security system is on. The bridge rectifier permits connection to the telephone lines without regard to their polarity and affords the continuity in telephone service.

The present invention relates to security alarm systems where the protected area has a telephone which is controlled by an attendant at a switchboard outside such area, who is to be informed when the alarm system is on so any signal received thereafter would indicate that the protected area is violated. Of course, the operator is also to be told when the system is again off.

An object of this invention is to provide a novel and improved alarm system in which an actuation in the protective circuit will operate the switchboard signal lamp or annunciator associated with said telephone, as it the receiver thereof had been taken off the hook; the telephone lines from the protected area to the switchboard, being shunted by means in the protected area, using the power in the telephone lines, and once this shunt occurs, it remains intact until there is a break in the line current, so although the protective circuit is restored, the signal at switchboard will continue until the operator plugs in.

Another object of this invention is to provide a novel and improved alarm system of the character described, which will allow normal operation of said telephone even when the alarm system is on, without triggering said system.

A further object thereof is to provide that the automatic shunt-creating means which associates the protective and signal circuits of the system, shall be capable of being housed in a compact casing for mounting within the protected area, ready for connection to said circuits, so the installing electrician can buy it as a unit, presenting proper terminals for connection into the system.

Another object thereof is to provide a novel and improved system of the character set forth, for protection against burglary, fire, smoke and the like, and combinations thereof.

Still a further object is to provide a novel and improved security alarm system of the kind set forth, which is easy to install, reasonable in cost, and efficient in carrying out the purposes for which it is designed.

Other objects and advantages will become apparent as this disclosure proceeds.

The accompanying drawing which is part of this specification, shows a preferred circuit diagram of a security alarm system embodying the teachings of this invention.

In the drawing, the numerals 10, 10' designate the lines connecting the telephone instrument designated generally by the numeral 11, which is in the protected area, as for instance a hotel room or an apartment. The numeral 12 denotes the receiver which though not shown so positioned, shall be deemed on the hook 13, holding it down, away from the contacts 14. Said telephone lines lead to the switchboard indicated generally by the numeral 15, which includes the electric lamp 16 powered by the direct current supply 17, and the key 18 for ringing the telephones bell 19, for which an alternating current supply 20 is used. The protective circuit is denoted generally by the numeral 21, and the casing shown by a dash-dot line 22, houses the signal-triggering means designated generally by the numeral 23, and preferably the condenser C, the condenser C", the resistance R, and the milliammeter 24.

The switch device designated generally by the numeral 25, at the entrance door to the protected area, is an ordinary shunt magnetic switch, here shown in its condition when the door is closed. It is a single pole, double throw switch, whose pole 26 is spring-biased towards the contact 2 7, but held by the magnet in contact with the contact 28, when the door is closed. Said magnet 29 is on the door, and the switch 25 is on the door frame. To permit a person to leave the room without breaking contact between said pole 26 and the contact 28, there is a spring-biased trip 30 which is set by the person in the room, to hold said pole, but such hold is undone by action of said magnet when the door is closed, as is well known, because the pole is shifted a bit by magnet action; the contact 28 being resiliently mounted to permit further shift of said pole.

The apparatus 23 presents the connection terminals 1, 2 and 3, which are respectively connected to the contact 28, the pole 26 and to the contact 27, and said apparatus also presents the connection terminals 4 and 5, which tap the telephone lines 10, 10 in the protected area. The numeral 31 designates generally an ordinary full-wave bridge rectifier employing the four rectifying elements D, D, D" and D, arranged to supply a plus charge to the anode 32 of a silicon-controlled rectifier 33, whose gate is G, and whose cathode is 34. A voltage divider comprises the resistances R and R'. There is an electrolytic condenser C for activating the silicon-controlled rectifier 33. The electrical connections of the said apparatus may be described as follows.

The input terminal 35 of the bridge rectifier 31, is connected by a conductor 36 to the terminal 4. The input terminal 37 of said bridge rectifier, is connected by a conductor 38 to the terminal 5; a switch 39, being interposed in said conductor 38. The output terminal 40 of said bridge rectifier, is connected by a conductor 41 toa terminal of the condenser C", and to a terminal of the resistance R, also to the terminal 1, and to the anode 32 of the silicon-controlled rectifier. The output terminal 42 of said bridge rectifier, is connected to the other terminal of the condenser C", and by a conductor 43 to a terminal of the milliammeter 24, the cathode 34 of the silicon-controlled rectifier, and to one terminal of resistance R' and one terminal of the condenser C'. The other terminal of the condenser C, is connected by a conductor 44, to the terminal 2. One terminal of the resistance R is connected by a conductor 45 to the terminal 3. The other terminals of the resistances R" and R', are connected to the gate G of the silicon-controlled rectifier. The other terminals of the resistance R and the milliammeter 24, are connected to each other.

In essence, where the door of the premises is protected by the switch device 25 in the system shown, the input terminals 35, 37 of the bridge rectifier 31, are connected to the telephone lines 10, in the protected area, and its output terminal lines 41, 43 have connected across them, the silicon-controlled rectifier 33, and further, the condenser C is maintained across said output lines while the protective circuit is intact, meaning while the switch parts 26 and 28 are in contact, but said condenser applies a signal to the gate G upon a violation of the protective circuit, meaning when the switch parts 26 and 27 are in contact, whereupon the silicon-controlled rectifier becomes conductive. The switch 39 is to set the system on or oil, and when on, the milliammeter 24, if actuated upon the closing of said switch, will indicate that the system throughout, is in working order. The condensers C and C" are for protective purposes.

It may be noted here, that the usual voltage of the current source 17 across the telephone lines 10, 10', is 48 volts DO, and that the ringing voltage of the current source 20, is 105 volts A.C. The switch 39 is open when the system is off. The mode of operation of the system, will now be given.

The occupant of the protected premises uses the telephone 11 to notify the operator at the switchboard 15, that the security system in his premises is to be put on. Then, of course, he returns the receiver 12 back onto its hook 13, thereby breaking contact of the elements 14. The operator having withdrawn the plug of connection, the DC. potential of 17, appears across the telephone lines 10, 10', and hence across the terminals 4 and 5, of the apparatus 23. Now the occupant closes the switch 39, whereupon said D.'C. potential appears at the input terminals 35 and 37 of the bridge rectifier 31. As mentioned, the elements D-D"" being arranged that the output delivered at terminal 40 is plus, and at terminal 42 is minus, it is evident that such polarity at said output terminals 40, 42 is constant, regardless of the polarity of the telephone lines 10, 10'. The electrician installing the apparatus need never ascertain the polarity of the telephone wires 10, 10', but can make the connections thereto indiscriminantly. This is one of the purposes which the full-wave bridge rectifier 31 serves in this sys tem. A second purpose thereof will be mentioned later.

It is evident that the power in the output lines 41 and 43, will actuate the milliammeter 24, if such power exists, and the resistance R is designed that the meter 24 shall indicate a center scale deflection upon passage therethrough of a current of approximately one milliampere DC. If there is trouble in the telephone line, there would be no actuation of said meter. The line potential now appears across the silicon-controlled rectifier 33, thereby giving its anode 32, a plus charge, but said rectifier remains non-conductive. However, as is Well known, it becomes conductive, when a charge is delivered to its gate G, when said rectifier is said to be triggered or fired. The function of the condenser C' is to supply such charge, if the door is opened. It is of course presumed that the occupant, either remained in the premises, or had left the premises, in which latter instance, he would have worked the trip 30, to permit him to leave without giving an alarm, which is a well known function and manipulation of the switch device 25. Also presumed is that the door is closed, so the switch parts 26 and 28 are in contact, as shown herein. This switch condition, places the condenser C" across the powered D.C. lines 43, 41 and is charged, for the switch condition of the contacting parts 26, 28, shunts the terminals 1 and 2.

Now if the door should be opened, meaning the protective circuit is violated, the switch parts 26 and 27 will be in contact, thereby shunting the terminals 2 and 3, which causes the condenser C to discharge, and direct a signal to the gate G, whereupon the silicon-controlled rectifier 33 will be fired and become conductive, thereby shunting the telephone lines 10, 10', which is as if the receiver 12 had been taken oil its hook 13. Now the signal lamp 16 will be actuated and will remain lit even if the door is closed by the intruder, because the siliconcontrolled rectifier 33 once made conductive, will remain so until there occurs even a momentary stoppage of the charge to its anode 32. So the lamp 16 will remain lit by this lock-in feature until the operator at the switchboard plugs in. Such lit lamp occuring while the operator knows that the security system is on, gives him notice that the protected area has been violated. Of course, when the system is to be set to off, the operator is advised thereof so he can cease his vigilance.

The condenser C across the input lines 36, 38, and the condenser C" across the output lines 41, 43, suppress line transients which may appear across said lines respectively, from time to time, which may fire the siliconcontrolled rectifier 33. Their presence is precautionary and not mandatory. The system Will also be operative without the meter 24 and its associated resistance R.

The second function of the bridge 31, is that it permits operation of the telephone system while the security system is on, for it isolates the A.C. ringing voltage from being blocked by the capacitor C. It said bridge was omitted, 0' would appear across the telephone lines, which in turn would bypass the ringing voltage, thus preventing the phone bell 19 from ringing. It is evident that this is effected, because the bridge 31 will allow only DC. to pass to said condenser C.

As a matter of example of values for a practical security system, its components may be as indicated below, namely:

C 0.01 mfd.

C" 0.01 mfd.

C' Electrolytic type, 10 mfd.,

200 v. or higher.

DD" 750 ma., each 200 v. or

higher.

R 47,000 ohms.

R" 3300 ohms.

R' 1000 ohms.

As a general rule, the door of the protected area, is the opening protected. If desired, the windows may also be protected, by having at each of them a switch device 50 which is well known in this art; such switch being of the type which is open when the window is closed, but which closes when the window is opened. All of said switches 50 are in parallel and across the terminals 2 and 3, the same as the open switch composed of pole 26 and the contact 27, which is at the door. When the system is on, opening of any of the windows would shunt the terminals 2 and 3, thereby firing the silicon-controlled rectifier 33, whereupon the lamp 16 will become lit and be a signal to the operator at the switchboard 15, that there is a break into the protected area.

To aid the identification of the various components recited in the appended claims, I have chosen to call C the first condenser, C the second condenser, and C" the third condenser, and to call R' the first resistance, R" the second resistance, and R the third resistance. Also, I designate the terminal 40 as the positive output terminal of the bridge rectifier 31, and the terminal 42, as its negative output terminal.

I claim:

1. In a security alarm system for protecting an area provided with a telephone whose lines lead to an attended switchboard outside said area where a signal means is actuated whenever the receiver of said telephone is removed from its normal rest position, said area having a closable opening associated with a switch device comprising a movable pole between spaced first and second contact points and means whereby said pole is in contact with the first contact point when said opening is closed, and in contact with said second contact point When said opening has been opened a predetermined number of times, an apparatus comprising a controlled electronic rectifier of the type having an anode, a cathode and a gate, which latter when subjected to a charge, makes said rectifier conductive so that current is allowed to flow from the anode to the cathode, a bridge rectifier having input terminals connected to the telephone lines respectively within said area, with a switch interposed in One of said connections, and said bridge rectifier having positive and negative output terminals, a first condenser for imposing a charge on said gate, a first resistance and a second resistance; said positive output terminal being connected to said anode and to said first contact point; the negative output terminal being connected to the cathode, and to one terminal of the first resistance and to one terminal of said condenser; the other terminal of the first resistance and one terminal of the second resistance being connected to said gate; the other terminal of said condenser being connected to said pole, and the other terminal of the second resistance being connected to the second contact point.

2. A construction as defined in claim 1, including a second condenser connected across the said input terminails.

3. A construction as defined in claim 1, including a condenser connected across said output terminals.

4. A construction as defined in claim 1, including a second condenser connected across said input terminals, and a third condenser connected across said output terminals.

5. A construction as defined in claim 1, including an electrically actuated means having a signal means, connected across said output terminals.

6. A construction as defined in claim 5, wherein said means having a signal means, comprises a milliammeter in series with a third resistance.

7. A construction as defined in claim 1, wherein the condenser for charging the gate, is of the electrolytic type.

References Cited UNITED STATES PATENTS 3,189,811 6/l9 65 King 307257 X 3,221,241 11/1965 Greenberg 32 l47 3,325,598 6/ 1967 ONeill. 3,360,777 12/ 1967 Kolm.

RALPH D. BLAKESLEE, Primary Examiner US. Cl. X.R. 307-257

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