US3815112A

US3815112A - Intrusion alarm

Info

Publication number: US3815112A
Application number: US00278956A
Authority: US
Inventors: D Kleber
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-08-09
Filing date: 1972-08-09
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04

Abstract

An improved intrusion alarm system is disclosed for protecting homes or businesses or other areas against entry by unauthorized persons. The system includes a central alarm device which is adapted for being coupled to a number of detecting stations positioned at doors or windows or other critical points. These separate detecting stations are coupled together by a single conductor protective electric loop. This loop contains one or more control stations which may be positioned at positions remote from the central alarm station and the control stations utilize the same single conductor protective loop to both test the loop and to turn the alarm system on and off. This multiple use of a single conductor, i.e. for protective, test, and off-on control is made possible by the use of light emitting diodes at the control stations which are operatively coupled into the single conductor protective loop for providing indicator and control functions.

Description

United States Patent 91 Kleber June 4, 1974 INTRUSION ALARM [76] Inventor: David Kleber, 2077 Glaisbury Dr., [57] ABSTRACT Westbury, NY. 11590 An improved intrusion alarm system is disclosed for [22] Filed: Aug 9, 1972 protecting homes or businesses or other areas against entry by unauthorized persons. The system includes a [Zl] Appl- 278,956 central alarm device which is adapted for being coupled to a number of detecting stations positioned at [521 ms. Cl. 340/214, 340/215, 340/276, i" critical POimS- These F 340/409 rate detecting stat ons are coupled together by a single 511 Int. Cl. G08b 23/00 mducm Protect z This 69mins [58] Field of Search 340/276, 214. 215, 409, one m stamns wh'ch may be f 340/214 at positions remote from the central alarm station and the control stations utilize the same single conductor [56] References and plrotective loop to biotl'li fte lstl the and tofturn the a arm system on an o lS mu tip e use 0 a sing e UNITED STATES PATENTS conductor, i.e. for protective, test, and off-on control is made possible by the use of light emitting diodes at CO Primary Examiner-David L. Trafton Attorney, Agent, or irmHolland, Armstrong, Wilkie & Previto the control stations which are operatively coupled into the single conductor protective loop for providing indicator and control functions.

9 Claims, 5 Drawing Figures 71?: PQOIECFI/E luv:

PATENTEDJUH 41914 SHEET 10F 2 PATENTEDJUH 41914 SHEET 2 OF 2 QQLQ QOKEQU INTRUSION ALARM BACKGROUND OF THE INVENTION The present invention relates to intrusion alarm systems which are installed in homes or businesses or other structures for protecting them against unauthorized entry. This system is particularly characterized by its use of a single conductor for coupling the various spaced detecting contacts and one or more control stations to a central power and alarm station. The system using the single conductor coupling not only provides a protective circuit but also provides for a test function and an on-off control at the remote control stations. These three functions are provided in the system using extremely low control currents and voltages so that the single conductor may have an extremely small size and so that installation is simple and power requirements are minimal.

There have been a large number of protective systems of this general type proposed for protecting against intrusion. Many of these prior systems utilize a minimum number of conductors but lack effective test and control systems. Others of the prior systems provide for continuity testing and for off-on operation at remote stations but require either multiconductor cables or high current systems in order to provide test or on-off functions in addition to the normal protective function. The use of high currents in these prior systems requires considerable insulation and high power drain. Additionally, heavily insulated and multiconductor cables present difficult installation problems.

The improved system of the present invention requires only one extremely small low current conductor for the protective and control loop and the low current requirements of the system require only low voltages and a conductor having minimal insulation as, for example, that required for only about a I or 12 volt system.

Accordingly, an object of the present invention is to provide an improved intrusion alarm system.

Another object of the present'invention is to provide an intrusion alarm'system including remote controls for circuit tests and off-on operation using the single conductor protective electric loop.

Another object of the present invention is to provide an improved intrusion alarm system provided with remote control stations and operating at low voltages and currents.

Another object of the present invention is to provide an improved intrusion alarm system utilizing light emitting diodes for control and indicating functions.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment'of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawing forming a part of the specification, wherein:

FIG. 1 is a schematic block diagram illustrating a preferred embodiment of the protective system.

DESCRIPTION OF THE PREFERRED EMBODIMENT The system will first be described generally with particular reference to FIGS. 1 and 2. The intrusion alarm system of the present invention is of the type for protecting a home or business or other structure or area where unauthorized intrusion is accompanied by the opening of a door or a window or by activating another device which includes a pair of normally closed contacts in a protective electrical loop. FIG; I shows such a protected zone at l with an alarm system 2 in accordance with the invention installed therein. In this example, two protected contacts 3 are shown coupled as, for example, at a door or a window in a protective loop 4 to prevent the unauthorized opening of either. Other numbers of contacts and other portions of .the zone may be similarly protected by additional contacts as, for example, in a second single wire loop.

A central control station 5 is illustrated which is coupled to a power source such as a regular commercial power supply which may be supplemented for emergency use with an internal battery in the known manner. The central station 5 includes analarm bell or other alarm device which might include means to activate a signal line to a remote surveillance station, such as a policestation. In addition, the alarm system includes control stations 6 one of which may be positioned at the central control station 5 and others which may be remotely positioned in the loop 4 as illustrated in FIGS. 1 and 2. v

The system shown in FIG. 1 is characterized by requiring only a single conductor in the loop .4 running between the central control and the control stations 6 and the protective contacts 3. As will be more fully described below, this single conductor loop also carries only a low current and operates at a low voltage of 10 volts or so requiring only a minimal insulation. FIG. I also illustrates a second single conductor protective loop 7 which may be run together with loop 3 for added security, as standard practice, but which need not be used if not required.

The protective contacts 3 may be of the type of normally closed element which is opened by an intrusive action. The remote, control stations 6 are provided so that the occupant may turn the alarm system on and off from a remote position and so that the occupant may test the loops 4 and 7 to insure that they are closed prior to his activating the alarm system 2. Such a control, for example, might be positioned adjacent a door or window permitting the occupant to switch the system off while opening the door or window and then permitting the alarm system to be immediately reactivated as soon as the opened element is closed or bypassed. In the preferred fonn of this remote control station 6, which will be described below, a visual indication is provided by light emitting diodes 8 (FIGS. 2 and 3) at the station to indicate whether the system if on" or foffl An on indication by the on diode 8 indicates that the alarm system is activated and that the protective loop is closed and energized. A test position is provided when the alarm is in the off position and a second indicator light is provided for this position which glows to indicate that the protective circuit is closed. This indicates that all of the protective contacts 3 are in their closed position and permits the alarm system 2 to be activated without the danger of a false alarm resulting from an inadvertent opened contact 3 or a defective protective contact 3.

A preferred embodiment of the remote control stations 6 will now be described and its operation as a portion of the overall system will be further clarified in the detailed description of the central control station which follows.

THE REMOTE CONTROL STATION Each of the remote control stations, as indicated above, are adapted for being serially coupled into the single conductor protective loop 4. The loop 4, for example, is cut at the desired point and the remote control station is coupled at 9 and 10 to ends of the loop conductor 4 as: illustrated in H0. 3. The remote stations 6 comprise a suitable mounting box containing a normally opened push button 11 with its terminals 12 connected to opposite sides of the protective loop 4 and with a pair of light emitting diodes 8 connected across the switch-contacts and arranged with opposite polarities, as shown.

The diodes 8 preferably are light emitting diodes such as the FLV-l02 diodes manufactured by the Fairchild Camera & Instrument Company. These diodes, in addition to their rectifying property, provide a visible glow when a current of about 5 milliamps is flowing through the diodes. For a current flow of this magnitude, the voltage drop across the diode is about 1.5 volts.

As will be described more fullybelow, the protective circuit loop 4 has a low voltage connected across it so that a current flow through the loop 4 and through the remote control station diodes 8 with the current being sufficient to provide 'a visible glow for the particular light emitting diode 8 which has the proper polarity for the particular current connection in use. The central control circuit 5, as will be described, is arranged to cause a current flow through the protective loop 4 in one direction for the test mode lighting one diode 8 and is arranged to have an opposite current flow for the alarm mode causing the-other diode 8 to glow thereby simultaneously indicating that the alarm system is on and that the protective loop is closed. The push button 11 is pressed-by the occupant to change from one mode to the otherby use of a switching circuit at the central control station in a manner which will now be described.

THE CENTRAL CONTROL STATION point 15 and thence through a control coil of the alarm relay l6 and then through the second protective loop 7, if required, to ground 14. The push button 11 in the individual control station 6, as described above, is operated to reverse the polarity of current flow through loop 4 by operating a bistable relay 17. This relay 17 operates the polarity reversing circuit 18 and at the same time in one position connects voltage to the alarm circuit 19 and in the other position disconnects the alarm 19.

As alreadyindicated, the polarity of the current flow through the first protective loop 4 illuminates the test light emitting diodes 8 at each remote station 6 for the test polarity position of the bistable relay l7 and illuminates the on diodes 8 when the bistable'relay 17 is in the alarm mode for an opposite current flow through loop 4. The bistable relay 17 is switched from one position to the other by a change in the voltage at point 15 which is caused by a shorting of the diodes 8 at any of the remote control stations 6 by pushing the button 11 at that station. Shorting these diodes 8 eliminates the voltage drop across them thereby'raising the voltage at point 15. When the voltage rises at point 15, the rise energizes relay 17 from voltage source 22 by activating the voltage rise detector 21, providing the protective line 3 has been previously closed and voltage detector 20 has been satisfied. This prevents an activation of relay 17 when the protective line is initially closed.

FlG. 5 illustrates a preferred embodiment of the circuit of H6. 4 using a number of transistors for the switching operations. The protective circuit is again illustrated at the right side of the figure running from 10 volt voltage source 13 to ground 14. This circuit is seen to have two alternate paths through the-first protective loop 4 between

terminals

24 and 25. The first of these paths is seen to include

transistors

26 and 27. When

transistors

26 and 27 are triggered through an application of voltage from the bistable relay contact 28, current flows through the first protective loop 4 from terminal 24 to terminal 25 and through the alarm relay l6 and the second protective loop 7 to ground. This is the test mode and the current is seen to pass through the closed protective contacts 3 in the first loop 4 and also to flow through and to light the test indicator diodes 8.

The second path is seen to include

transistors

29 and 30 whereby current flows in the opposite direction.

around the first protective loop 4 and thence through the alarm relay 16 to ground 14. When current is flowing in this direction around the first protective loop 4, the on diodes are seen to be lighted indicating that the alarm is operative.

The remaining portion of the circuit is provided to switch the direction of current flow around the first protective loop 4 from one direction to theother to give the above results. This switching is accomplished by pushing the button 11 at any remote control station 6. When the botton 11 is pushed, the voltage drop across the diodes 8 at that station is eliminated thereby causing a significant voltage increase at point 15. The voltage of point 15 is fed through two

transistors

31 and 32 to turn them on to permit current flow through control coil 33 of the bistable relay 17. This current flow causes the relay 17 contacts 34 to move from their test position to the on position or vice versa depending upon its initial position. Transistor 35 is included in the voltage source for transistor 31 to provide a time delay control through the time constant of the

capacitor resistor combination

36,37. Transistor 35 turns on after the protective line has been closed a short interval and thereby protects the bistable relay 17 against being activated when the protective line is initially closed.

It will be seen that an improved intrusion alarm has been provided which protects a home or business or other area having a number of openings and where only a single conductor connecting cable is required for the protection and the control circuit. The single conductor circuit not only provides the protection function but it also operates in the preferred system for providing a test signal and an on-off control both of which may be operated from a number of remote control stations positioned at various points along the protective circuit. The system is also particularly advantageous as it is a low current and a low voltage system requiring only a small gauge single conductor with a minimal amount of insulation thereby facilitating installation and minimizing any electrical hazards.

As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

I. In a detection system having one or more normally closed first switches and a current flow detector coupled in a series circuit and adapted for connection to a DC current source, the improvement comprising means for switching the current direction through said switches including means for changing the current value in said circuit comprising means for indicating the direction of current through said first switches and a second switch coupled across said indicating means, alarm means, and said switching means including means to connect said alarm to said current flow detector for one direction of currentflow only through said first switches.

2. The detection system as claimed in claim 1 in which said indicating means comprises a pair of light emitting diodes connected in parallel with each other with opposite polarities and with the parallel coupling connected serially in said circuit.

3. The detection system as claimed in claim 1 in which said switching means comprises a bi-stable relay.

4. The detection system as claimed in claim 1 in which said switching means comprises a bi-stable relay coupled to said circuit by amplifying means.

5. The detection system as claimed in claim 4 in which said amplifying means includes a time delay means.

6. The detection system as claimed in claim 1 in which said switches are connected to each other and to the DC current source by a single conductor.

7. In a detection system having one or more normally closed switch contacts and a current flow detector coupled in a series circuit adapted for connection to a DC current source, the improvement comprising means for switching the current direction in a portion of said circuit, said switching means being operated by a change in current value in said circuit and including means in said portion of said circuit to indicate the direction of current flow, alarm means, said switching means including means to connect said alarm to said detector for one direction of current flow only through said portion of said circuit and said indicator means comprising a pair of light emitting diodes connected in parallel with each other and having opposite polarities, and a switch connected across said diodes.

8. In a detection system having one or more normally closed switch contacts and a current flow detector coupled in a series circuit and coupled to a DC current source, the improvement comprising the coupling to said current source including a pair of light emitting diodes coupled in parallel with each other and with opposite polarities, means for switching the polarity of the voltage across said diodes, said switching means including a switch to short said diodes to change the current value in said circuit, alarm means, and said switching means including means to connect said alarm to said detector for one voltage polarity across said diodes.

9.-ln a detection system having one or more normally closed first switches and a current flow detector coupled in a series circuit and adapted for connection to a DC current source, the improvement comprising switching means for changing the current direction through said first switches including means for changing the current value in said series circuit, alarm means, said switching means including means to connect said alarm to said current flow detector for one direction of current flow only through said first switches, and said switching means further comprising a relay, the coil of said relay being coupled to a voltage source through second switch means, and said second switch means comprising a transistor controlled by said series circuit.

Claims

1. In a detection system having one or more normally closed first switches and a current flow detector coupled in a series circuit and adapted for connection to a DC current source, the improvement comprising means for switching the current direction through said switches including means for changing the current value in said circuit comprising means for indicating the direction of current through said first switches and a second switch coupled across said indicating means, alarm means, and said switching means including means to connect said alarm to said current flow detector for one direction of current flow only through said first switches.

9. In a detection system having one or more normally closed first switches and a current flow detector coupled in a series circuit and adapted for connection to a DC current source, the improvement comprising switching means for changing the current direction through said first switches including means for changing the current value in said series circuit, alarm means, said switching means including means to connect said alarm to said current flow detector for one direction of current flow only through said first switches, and said switching means further comprising a relay, the coil of said relay being coupled to a voltage source through second switch means, and said second switch means comprising a transistor controlled by said series circuit.