Sensitivity measuring apparatus for use with a fire detector

• US 5,453,749 A
• Filed: 05/26/1993
• Issued: 09/26/1995
• Est. Priority Date: 05/28/1992
• Status: Expired due to Fees

• Current Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Original Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Inventors: Morita, Toshikazu
• Primary Examiner(s): Williams, Howard L.
• Application Number:
  US08/067,147
• Time in Patent Office: 853 Days
• Field of Search: 364/550, 364/553, 364/571.01, 364/571.03, 341/118, 341/120
• US Class Current: 341/118
• CPC Class Codes: G08B 29/26 by updating and storing reference thresholds

Abstract

A sensitivity measuring apparatus for use with a fire detector comprising includes sensitivity measuring portions, a calibrating signal generator, and a calibrator. The sensitivity measuring apparatus also includes a type identifier for the type of the fire detector on the basis of the output signal from the fire detector. The apparatus thus needs no manpower during its adjustment procedure to regulate the tolerance of the internal circuit. The apparatus also eliminates a source of erroneous measurements in the course of sensitivity measurement of the fire detector.

Claims

1. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a sensitivity measuring means for receiving an output signal of the fire detector so as to measure the sensitivity of the fire detector;

a reference signal generating means for generating a reference signal for calibration of the apparatus; and

a calibrating means for calibrating the sensitivity measuring apparatus on the basis of the reference signal generated by the reference signal generating means.

2. The apparatus according to claim 1, wherein said sensitivity measuring means comprises:

an analog signal processing means for processing an analog signal which is said output signal from the fire detector;

an A/D converter means for receiving and converting the analog signal processed by the analog signal processing means into a digital signal; and

a digital signal processing means for receiving and processing the digital signal converted by the A/D converter means.

3. The apparatus according to claim 2, wherein said calibrating means includes means for calibrating the digital signal which is output from the A/D converter means to the digital signal processing means in the sensitivity measuring means.

4. The apparatus according to claim 2, wherein said analog signal processing means performs at least one of the three functions of an impedance matching function for the signal, an amplifying function of the signal and a signal holding function.

5. The apparatus according to claim 1, wherein said sensitivity measuring means comprises a sensitivity output means for outputting measured sensitivity values, and wherein said calibrating means calibrates said sensitivity output means on the basis of the reference signal generated by the reference signal generating means.

6. The apparatus according to claim 5, wherein said sensitivity output means comprises:

a D/A converting means for converting a digital signal into an analog signal; and

a digital signal processing means for receiving and processing the digital signal input to the D/A converting means.

7. The apparatus according to claim 6, wherein said calibrating means includes means for calibrating the digital signal output from the digital signal processing means to the D/A converting means in the sensitivity output means.

8. The apparatus according to claim 5, further comprising a signal output inhibit means for inhibiting an externally output signal from the sensitivity output means while the calibrating means performs a calibration operation.

9. The apparatus according to claim 1, wherein said calibrating means calibrates the sensitivity measuring means each time the sensitivity measuring apparatus is switched on.

10. The apparatus according to claim 1, further comprising a calibration result output means for outputting the result of a normal calibration or an abnormal calibration on the basis of the calibration result provided by the calibrating means.

11. The apparatus according to claim 1, further comprising a signal input inhibit means for inhibiting any external signal from being inputted to the sensitivity measuring apparatus while the calibrating means performs a calibration operation.

12. The apparatus according to claim 1, wherein said calibrating means calibrates the sensitivity measuring means every predetermined time period.

13. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a sensitivity measuring means for receiving the output signal of the fire detector so as to measure the sensitivity of the fire detector; and

a type identifying means for identifying the type of the fire detector on the basis of one of either an overall time when the output signal is output from the fire detector and a period of the output signal from the fire detector.

14. The apparatus according to claim 13, further comprising a type output means for outputting the type identified by the type identifying means.

15. The apparatus according to claim 14, wherein said type output means comprises a display means for displaying identified result.

16. The apparatus according to claim 14, wherein said type output means comprises a sound output means for outputting identified result by sound.

17. The apparatus according to claim 13, wherein said sensitivity measuring means comprises a plurality of sensitivity measuring portions corresponding to a plurality of types of fire detectors, and said apparatus comprises selecting means for selecting one of said plurality of sensitivity measuring portions corresponding to the type of the fire detector identified by the type identifying means.

18. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a signal detecting means for detecting any one of a magnitude, frequency and signal output duration of an output signal from the fire detector;

a sensitivity measuring means for measuring the sensitivity of the fire detector on the basis of the signal output from an output terminal of the fire detector;

a clock signal supplying means for supplying a clock signal to the sensitivity measuring means; and

a supply stop means for stopping the supply of the clock signal from the clock signal supplying means to the sensitivity measuring means when the signal detecting means detects an absence of an output signal from the fire detector during a predetermined time period.

19. The apparatus according to claim 18, further comprising a supply start means for starting the supply of the clock signal from the clock signal supplying means to the sensitivity measuring means when the signal detecting means detects the output signal of the fire detector.

20. The apparatus according to claim 19, wherein said sensitivity measuring means comprises:

an analog signal processing means for receiving and processing the analog signal output from the fire detector;

an A/D converter means for receiving and converting the analog signal processed by the analog signal processing means into a digital signal;

a digital signal processing means for receiving and processing the digital signal converted by the A/D converter means; and

an output means for outputting a result processed by the digital signal processing means.

21. The apparatus according to claim 20, wherein said analog signal processing means performs at least one of the three functions of an impedance matching function for the signal, an amplifying function of the signal and a signal holding function.

22. A sensitivity measuring apparatus a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a signal detecting means for detecting any one of a magnitude, frequency and signal duration of an output signal from the fire detector;

a sensitivity measuring means for measuring the sensitivity of the fire detector on the basis of the signal detected by the signal detecting means;

a power supply means for supplying power to the sensitivity measuring means; and

a supply stop means for stopping the supply of power from the power supply means to the sensitivity measuring means when the signal detecting means detects an absence of an output signal from the fire detector during a predetermined time period.

23. The apparatus according to claim 22, further comprising a supply start means for starting the supply of power from the power supply means to the sensitivity measuring means when the signal detecting means detects the output signal of the fire detector.

24. The apparatus according to claim 23, wherein said sensitivity measuring means comprises:

an analog signal processing means for receiving and processing the analog signal output from the fire detector;

an A/D converter means for receiving and converting the analog signal processed by the analog signal processing means into a digital signal;

a digital signal processing means for receiving and processing the digital signal converted by the A/D converter means; and

an output means for outputting a result processed by the digital signal processing means.

25. The apparatus according to claim 24, wherein said analog signal processing means performs at least one of the three functions of an impedance matching function for the signal, an amplifying function of the signal and a signal holding function.

26. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a measuring means for measuring an output signal from the fire detector to obtain measured data every predetermined time period;

an extracting means which extracts a second predetermined number of measured data from among a group of data consisting of a first predetermined number of measured data greater than the second predetermined number of measured data, in the order in which extracting priority is given over smaller mutual differences; and

a mean-value calculating means for calculating a mean value of the measured data extracted by the extracting means, and a sensitivity determining means for determining the sensitivity of the fire detector on the basis of the mean value calculated by the mean-value calculating means.

27. The apparatus according to claim 26, wherein said extracting means updates said group of data by replacing the group'"'"'s oldest measured data with newly obtained data each time the said measuring means measures the output signal from the fire detector.

28. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

a reference voltage generating circuit for generating a reference voltage for calibration;

an amplifier for amplifying an analog signal output from an output terminal of the fire detector;

a sample and hold circuit for sampling and holding the output from said amplifier;

an A/D converter for converting an analog signal output from said sample and hold circuit into a digital signal;

a first memory for storing a reference voltage generated from said reference voltage generating circuit;

a second memory for storing the amplification degree of said amplifier;

a first switching circuit for inputting the reference voltage generated from said reference voltage generating circuit into said A/D converter;

a second switching circuit for inputting the reference voltage generated from said reference voltage generating circuit into said sample and hold circuit;

a third switching circuit for inputting the reference voltage generated from said reference voltage generating circuit into said amplifier;

a first calculating circuit for comparing an output from said A/D converter with the reference voltage stored in said first memory when the reference voltage is input into said A/D converter through said first switching circuit and for calculating a first error correction coefficient so as to correct the output from said A/D converter to the reference voltage stored in said first memory when the output from said A/D converter differs from the reference voltage as a result of the comparison;

a second calculating circuit for comparing the output from said A/D converter with the reference voltage stored in said first memory when the reference voltage is input into said sample and hold circuit through said second switching circuit and for calculating a second error correction coefficient so as to correct the output from said A/D converter to the reference voltage stored in said first memory when the output from said A/D converter differs from the reference voltage as a result of the comparison;

a third calculating circuit for comparing the output from said A/D converter with the product of the reference voltage stored in said first memory and the amplification degree stored in said second memory when the reference voltage is input into said amplifier through said third switching circuit and for calculating a third error correction coefficient so as to correct the output from said A/D converter to the reference voltage stored in said first memory when the output from said A/D converter differs from the reference voltage as a result of the comparison;

a calibrating circuit for calibrating the output from said A/D converter by using at least the third error correction coefficient calculated by said third calculating circuit when said amplifier is connected to the output terminal of the fire detector to measure the sensitivity of the fire detector, and

an output circuit for converting the output calibrated by said calibrating circuit into the sensitivity of the fire detector to output the converted sensitivity.

29. The apparatus according to claim 28, wherein said second calculating circuit calculates the second error correction coefficient by using the first error correction coefficient, said third calculating circuit calculating the third error correction coefficient by using the first and second error correction coefficients, said calibrating circuit calibrating the output from said A/D converter by using the first, second and third error correction coefficients, said output circuit including a third memory for storing a table between the output value and the sensitivity value of the fire detector and a forth calculating circuit for calculating the sensitivity value on the basis of the calibrated output by using the table stored in said third memory.

30. A sensitivity measuring apparatus which is connected to a fire detector for measuring the fire detector sensitivity, said sensitivity measuring apparatus comprising:

an amplifier to which an analog output port of the fire detector is connected;

a sample and hold circuit for sampling and holding the output from said amplifier;

an A/D converter for converting the output from said sample and hold circuit into a digital signal;

a switching circuit which is normally OFF for bypassing said amplifier and said sample hold circuit when in an ON state;

a signal distinguishing circuit to which an analog output port of the fire detector is connected for distinguishing whether the analog output from the fire detector is a pulse signal or a direct current signal; and

a control circuit for turning said switching circuit ON when said signal distinguishing circuit distinguishes that the analog output from the fire detector is a pulse signal.