System for the early detection of fires

• US 5,751,209 A
• Filed: 11/20/1994
• Issued: 05/12/1998
• Est. Priority Date: 11/22/1993
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Cerberus ABP Investor LLC (Cerberus Capital Management LP)
• Inventors: Schlegel, Max, Werner, Jurg
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US08/345,735
• Time in Patent Office: 1,269 Days
• Field of Search: 340/286.05, 340/622, 340/517, 340/521, 340/523, 340/693
• US Class Current: 340/286.05
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 29/16 Security signalling or alarm systems, e.g. redundant systems

Abstract

A fire detection system contains several detectors connected to a control center, some of which are fitted with at least two sensors for monitoring different fire parameters. Preferably, one sensor is a thermal sensor and another is an optical sensor. An arrangement for processing the sensor signals is located within each of the detectors. It contains a microcontroller for conditioning the sensor signals and for signal processing, with the aim of generating alarm signals. The alarm signals are obtained in a neural network.

Claims

1. A system for the early detection of fires, comprising:

a plurality of detectors connected to a control center, wherein each of said detectors includes at least one sensor for monitoring a fire-related parameter; and

a means for processing sensor signals located in each of said detectors to generate alarm signals for transmission to said control center, each of said processing means including a microcontroller for conditioning said sensor signals, signature producing means for receiving a conditioned sensor signal and generating therefrom a plurality of signature signals wherein each of said signature signals includes information regarding a shape of said conditioned sensor signal, and a neural network to which said signature signals are applied to generate said alarm signals.

2. The system of claim 1, wherein at least one of said detectors includes at least two sensors for monitoring different respective fire-related parameters, and wherein said processing means for a detector having at least two sensors comprises a separate signal processing channel for each of the sensors in the detector, and wherein signals processed in each of said channels are input to the neural network for the detector.

3. The system of claim 2 wherein each of said neural networks contains multiple levels each having nodes in which input variables are weighted, and wherein each node carries out an addition of the weighted input variables or a selection of the maximum or minimum weighted variable.

4. The system of claim 1 wherein each of said neural networks contains multiple levels each having nodes in which input variables are weighted, and wherein each node carries out an addition of the weighted input variables or a selection of the maximum or minimum weighted variable.

5. The system of claim 1 wherein the microcontroller for each processing means includes a memory storing an operating system and sensor software.

6. The system of claim 2 wherein one of said sensors is an optical sensor having a light transmitter, and wherein the signal processing channel for said optical processor includes an ASIC containing an amplifier and a filter for signals generated by the optical sensor, a temperature sensor, and drive electronics for the light transmitter in the optical sensor.

7. The system of claim 2 wherein one of said sensors is a thermal sensor, and wherein the signal processing channel for said thermal sensor includes a biassing network for said sensor, an analog-to-digital converter, a signal compensation stage, and a stage for producing signal signatures that are provided as input signals to said neural network.

8. The system of claim 7 wherein said signal compensation stage includes a voltage compensation circuit, a noise-removal circuit, a temperature conversion circuit for generating a temperature signal, and a circuit for compensating the temperature signal for heat dissipation and thermal capacity of components associated with the sensor.

9. The system of claim 8 wherein said noise-removal circuit limits changes in the sensor signal from one measurement to the next.

10. The system of claim 7 wherein said signature producing stage comprises means for linking output signals from components of said thermal sensor channel to produce multiple signature signals for input to said neural network.

11. The system of claim 6 wherein said channel for said optical sensor includes a pulse generator for driving said transmitter, an integrator for integrating signals from said sensor, an analog-to-digital converter, a signal compensation stage, and a stage for producing signal signatures that are provided as input signals to said neural network.

12. The system of claim 11 further including a voltage amplifier located downstream of said integrator in said stage for providing course adjustment of sensor signals, and a filter located downstream of said amplifier for detecting received light pulses and suppressing interference signals.

13. The system of claim 12 wherein said filter processes sensor signals before, during and after a detected light pulse.

14. The system of claim 11 wherein said signal compensation stage includes a circuit for determining effective signal deviation, a temperature compensation circuit for providing fine adjustment of the sensor signal, and a correction circuit for removing the effects of long-term environmental changes.

15. The system of claim 11 wherein said signature producing stage comprises means for filtering signals produced by said signal compensation stage to analyze their time characteristics and to thereby produce multiple signature signals for input to said neural network.

16. The system of claim 2 wherein each of said channels produces multiple signature signals related to its associated sensor, and said signature signals are combined in said neural network to produce a scaler alarm signal.

17. The system of claim 16 further including a verification stage for classifying said scaler alarm signal produced by said neural network.

18. The system of claim 1 wherein said signature producing means includes a digital filter bank for receiving a conditioned sensor signal and generating therefrom a plurality of signature signals that are provided as input signals to said neural network.

19. The system of claim 18 wherein said filter bank contains recursive filters.

20. The system of claim 18 wherein said filter bank contains means for performing Fourier transforms.

21. The system of claim 18 wherein said filter bank contains correlators.

22. A system for the early detection of fires, comprising:

a plurality of detectors connected to a control center, wherein at least some of said detectors include at least two sensors each for monitoring different respective fire-related parameters; and

a means for processing sensor signals located in each of said detectors to generate alarm signals for transmission to said control center, each of said processing means including a microcontroller for conditioning said sensor signals, a digital filter bank for receiving a conditioned sensor signal and generating therefrom a plurality of signature signals wherein each of said signature signals includes information regarding a shape of said conditioned sensor signal, and a neural network to which said conditioned sensor signals and signature signals are applied to generate said alarm signals.

23. A system for the early detection of fires, comprising:

a sensor for monitoring a fire-related parameter and for producing a corresponding sensor output signal;

means for processing said sensor output signal to generate a plurality of signature signals wherein each of said signature signals includes information regarding a shape of said sensor output signal; and

a neural network to which said signature signals are applied for generating an alarm signal.

24. A method for detecting fires, comprising the steps of:

measuring a fire-related parameter over time to generate a time-varying signal which is proportional to said fire-related parameter;

processing said time-varying signal to generate a plurality of signature signals wherein each of said signature signals includes information regarding a shape of said time-varying signal; and

combining said signature signals in a neural network to generate a fire alarm signal.

25. A system for the early detection of fires, comprising:

a plurality of detectors connected to a control center, wherein each of said detectors includes at least one sensor for monitoring a fire-related parameter; and

a means for processing sensor signals located in each of said detectors to generate alarm signals for transmission to said control center, each of said processing means including a microcontroller for conditioning said sensor signals, signature producing means for receiving a conditioned sensor signal and generating therefrom a plurality of signature signals, and a neural network to which said signature signals are applied to generate said alarm signals, wherein each of said neural networks contains multiple levels, each level having nodes in which input variables are weighted, wherein nodes in a number of said levels add weighted input variables and nodes in other of said levels select one of a maximum weighted variable and a minimum weighted variable.