Intrusion alarm sensing unit

• US 5,216,410 A
• Filed: 11/16/1990
• Issued: 06/01/1993
• Est. Priority Date: 11/16/1990
• Status: Expired due to Term

• Current Assignee: Tyco Safety Products Canada Limited (Johnson Controls International plc)
• Original Assignee: Digital Security Controls Limited (Johnson Controls International plc)
• Inventors: Pildner, Reinhart K., Cecic, Dennis
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/614,239
• Time in Patent Office: 928 Days
• Field of Search: 340/509, 340/500, 340/506, 340/522, 340/521, 340/507
• US Class Current: 340/509
• CPC Class Codes: G08B 29/02 Monitoring continuously signalling or alarm systems
• CPC Class Codes: G08B 29/16 Security signalling or alarm systems, e.g. redundant systems
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence

Abstract

The present invention is directed to an intrusion detection system having two different types of motion sensors and processing of the signals produced by the motion sensors in a manner to provide a reliable indication of motion within the space being sensed. The intrusion detection system includes a microprocessor and produces an alarm signal if each sensor is activated within a predetermined time period of each other. The unit is also capable of producing what is referred to as a "trouble" signal, based upon a certain number of unconfirmed event signals, i.e. a signal from only one sensor being received, within a predetermined time, indicating that one of the sensors is not operating properly. Once a certain number of unconfirmed event signals are received, the unit operates in one of at least two different default modes whereby a trouble signal or trouble signal and alarm signal are produced by means of a different logic processing step. The invention is also directed to an intrusion detection system having dual sensors where the user can automatically reset the unit should the system have gone into default mode operation. This is particularly useful in that it reduces service on the units and also provides an easy, convenient manner for the user to restore the device to normal operation when required.

Claims

1. In an intrusion detection system having at least one sensing unit, each sensing unit comprising at least two motion sensors with each sensor, when activated, producing an unconfirmed event signal indicating detection of motion, and logic processing means for monitoring said unconfirmed even signals of said sensors and producing an alarm signal if both sensors produce unconfirmed event signals within a predetermined time of each other thus confirming the event signals;

said logic processing means processing said unconfirmed event signals to determine a possible malfunction of the sensing unit and producing a trouble signal based on the processed unconfirmed event signals received, said logic processing means including selectable means which when selected causes said logic processing means to process further unconfirmed event signals received after a trouble signal has been produced to produce an alarm signal when said further unconfirmed event signals satisfy a predetermined criteria whereby an alarm signal can be produced based upon the receipt of unconfirmed event signals in addition to the alarm signal being produced upon receive of confirming event signals.

2. In an intrusion detection system as claimed in claim 1 including means of determining the last sensor to produce an unconfirmed event signal resulting production of a trouble signal to assist in user system analysis.

3. In an intrusion detection system as claimed in claim 2 wherein

said predetermined function of said logic processing means produces an alarm signal upon the further receipt of two additional unconfirmed event signals within a preset time period.

4. In an intrusion detection system as claimed in claim 1 wherein each sensor includes a light emitting diode which flashes when the unit is activated and which remains on if the sensor is the last sensor to produce an unconfirmed event signal which causes said logic processing means to produce an alarm signal.

5. In an intrusion detection system having at least one sensing unit, each sensing unit comprising at least two motion sensor with said sensors, when activated, producing unconfirmed event signals indicating detection of motion, and logic processing means for monitoring said unconfirmed event signals and producing an alarm signal if both sensors produce unconfirmed event signals within a predetermined time of each other thus confirming the event signals;

said logic processing means processing said unconfirmed event signals to determine a possible malfunction of the sensing unit and producing a trouble signal based on the processed unconfirmed event signals received, sad logic processing means including selectable means which when selected causes said logic processing means to process unconfirmed event signals to produce an alarm signal when the unconfirmed event signals satisfy a predetermined criteria whereby an alarm signal can be produced based upon the receipt of unconfirmed event signal in addition to the alarm signal being produced upon receipt of confirming event signals.

6. In an intrusion detection system having at least one sensing unit having two motion sensors which cooperate in normal operation to produce an alarm when both sensors are activated and which can operate in a default mode to produce a warning type signal based upon a number of unconfirmed evens with each unconfirmed event being determined by receipt of a signal from one of said sensors while the other sensor is not activated within a predetermined time period;

a method of automatically resetting the unit from the default mode to normal operation when the unit senses a predetermined number of consecutive occurrences where both sensors are activated whereby the unit is reset to normal operation.

7. In an intrusion detection system having at least one sensing unit with each sensing unit having at least two motion sensor producing unconfirmed event signals when activated, a method of processing the signals of the sensors comprising monitoring the sensor and determining when each sensor is activated and producing an unconfirmed event signal indicating detection of motion by the activated sensor, in normal operation monitoring the confirmed event signals and producing an alarm signal fi both sensor produce unconfirmed event signals within a predetermine time of each of the thus confirming the event signals;

processing the unconfirmed event signals to determine a possible malfunction of the sensing unit and when a malfunction is indicted operating the unit in a default condition which produces a trouble signal based on the processed unconfirmed event signals received and produces an alarm signal when received unconfirmed event signals satisfy a predetermined criteria in addition to creating an alarm signal when confirmed event signals are received and continuing to monitor the signals to recognize a reset condition function for resetting from a default condition to normal operation based upon sensing a predetermined number of consecutive confirmed event signals.

8. In an intrusion detection system as claimed in claim 7 including counting the unconfirmed events of said sensors and when a trouble signal is produced counting confirmed event signals and decreasing by one the counted unconfirmed event signals and upon reaching zero resetting the sensing unit.

9. In an intrusion detection system having at least one sensing unit, each sensing unit comprising at least two motion sensors with each sensor, when activated, producing an unconfirmed event signal indicating detection of motion, and logic processing means for monitoring said unconfirmed event signals and producing an alarm signal if both sensors produce unconfirmed event signals within a predetermined time of each other thus confirming the event signals;

said logic processing means processing said unconfirmed event signals to determine a possible malfunction of the sensing unit and producing a trouble signal based on the processed unconfirmed event signals received, said logic processing means including a reset condition function for resetting from a trouble condition based upon sensing a predetermined number of consecutive confirmed event signals whereafter the unit returns to normal operation.

10. In an intrusion detection system as claimed in claim 9 wherein the predetermined number of consecutive counts is the same number as the number of unconfirmed event signals required to produce a trouble signal.

11. In an intrusion detection system as claimed inc claim 10 wherein said logic means includes a counting means for counting unconfirmed events of said sensor, said counting mean when a trouble signal is produced counting confirmed event signals and decreasing by one the counted unconfirmed event signals and upon reaching zero resetting the sensing unit.

12. In an intrusion detection system having at least one sensing unit, each sensing unit comprising at least two motion detection sensors scanning the same area and logic processing mans for processing the output of said motion sensors, each sensing unit including input means associated with said logic processing which adjusts said logic processing means to operate in one of at least two separate and distinct modes with respect to operation of the sensing unit when a trouble signal is generated, said logic processing means producing an alarm signal when separate output signals of said sensor are received within a predetermined time period of each other to indicate a confirmed event, said logic processing means further processing said signals to provide a trouble signal based upon receipt and processing of unconfirmed events, an unconfirmed event being determined by a signal being received from one of si sensors without receiving a corresponding signal from the at least one other sensor within the predetermined, and wherein said at least two separate and distinct modes include;

a) producing only a trouble signal while continuing to operate the sensing unit and producing an alarm signal upon a confirmed event, and

b) producing a trouble signal based upon receipt and processing of unconfirmed events, and producing an alarm signal upon a confirmed event, or upon receipt and processing of unconfirmed events which occur after the generation of a trouble signal and which satisfy a predetermined criteria.

13. In an intrusion detection system as claimed in claim 12 wherein the generation of an alarm upon receipt and processing of unconfirmed events is produced upon receipt of a certain number of unconfirmed events within a preset time period.

14. In an intrusion detection system as claimed in claim 12 wherein the generation of an alarm upon receipt and processing of unconfirmed events is produced upon receipt of a certain number of unconfirmed events received from any sensor within a preset time period.

15. In an intrusion detection system as claimed in claim 12 wherein said sensing unit includes means for indicating the last sensor to operate causing the generation of a trouble signal.

16. In an intrusion detection system as claimed in claim 12 wherein said logic processing means including user effected reset condition function for resetting from a trouble condition based upon sensing a predetermined number of consecutive confirmed event signals whereafter the unit returns to normal operation.