Fire alarm system

• US 4,803,469 A
• Filed: 07/14/1986
• Issued: 02/07/1989
• Est. Priority Date: 07/18/1985
• Status: Expired due to Fees

• Current Assignee: Hochiki Kabushiki Kaisha
• Original Assignee: Hochiki Corporation
• Inventors: Matsushita, Eiji
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Chau, Annie H.
• Application Number:
  US06/884,976
• Time in Patent Office: 939 Days
• Field of Search: 340/511, 340/514, 340/870.21, 364/550, 364/557, 364/555, 364/178, 364/551
• US Class Current: 340/577
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion

Abstract

A fire alarm system which comprises one or more detecting sections for detecting a change in the surrounding phenomena due to a fire in an analog form; a storing section for storing the analog data output from the detecting section or sections; a level comparing section for comparing a data level represented by present instantaneous analog data output from the detecting section or sections and a predetermined level; fire judging instructing section which extracts a plurality of data stored during a predetermined period of time back to from the time when a comparison signal is obtained from the level comparing section, calculates a change amount between the respective extracted data and generates an output for initiating the calculation when the number of the calculated change amounts exceeding a predetermined amount exceeds a predetermined number; and a fire judging section for receiving the data stored in the storing section in response to the signal from the comparing section and/or fire judging instructing section to judge a fire.

Claims

1. A fire alarm system which comprises:

one or more detecting sections for detecting a change in the surrounding phenomena due to a fire and outputting data in an analog mode;

a data processing section receiving said outputted analog data from the detecting section or sections at intervals and smoothing said analog data by interrelating analog data from a plurality of said intervals;

a storing section for storing the smoothed data output from the data processing section;

a level comparing section for comparing a data level represented by present smoothed data output from the detecting section or sections with a preset level and producing a comparison signal when such level is exceeded;

a fire judging instructing section which extracts a plurality of data stored during a predetermined period of time preceding the time when a comparison signal is obtained from the level comparing section, calculates a change amount between the respective extracted data, determines the number of data for which such change amounts exceed a predetermined value, and generates a signal for instructing the start of a fire judgment calculation when the number of such data exceeds a predetermined number; and

a fire judging section for making a fire judgment calculation in response to the signal from the fire judging instructing section.

2. A fire alarm system according to claim 1, in which said fire judging section carries out a predictive calculation of fire from the data stored in the storing section in response to the signal from the fire judging instructing section.

3. A fire alarm system according to claim 1, wherein said data processing section for processing the analog data which is provided by said detecting section calculates moving averages of a predetermined number of such data and output the moving averages to the storing section.

4. A fire alarm system according to claim 1, wherein said change amount is calculated in terms of the differences between the respective stored data.

5. A fire alarm system according to claim 4, wherein said respective stored data are consecutive in time.

6. A fire alarm system according to claim 4, wherein said respective stored data are every other data in time.

7. A fire alarm system according to claim 3, wherein said change amount is calculated in terms of the quotient of the difference between the respective stored data and the difference between the detection times of the respective stored data.

8. A fire alarm system according to claim 7, wherein said respective stored data are consecutive in time.

9. A fire alarm system according to claim 7, wherein said respective stored data are every other data in time.

10. A fire alarm system which comprises:

one or more detecting sections for detecting a change in the surrounding phenomena due to a fire and outputting data in an analog mode;

a data processing section receiving said outputted analog data from the detecting section or sections at intervals and smoothing said analog data by interrelating analog data from a plurality of said intervals;

a storing section for storing the smoothed data output from the data processing section;

a level comparing section for comparing a data level represented by present data output from the processing section with a preset level and producing a comparison signal when such level is exceeded;

a fire judging instructing section which extracts a plurality of data stored and calculates a change amount between the respective extracted data and generates an output for instructing the start of a fire judgement when the number of the calculated change amounts exceeding a predetermined amount exceeds a predetermined number; and

a fire judging section for judging the fire in response to the comparison signal from the level comparing section and the fire judging instructing section.

11. A fire alarm system according to claim 10, in which said fire judging section carries out a predictive calculation of fire upon receiving the output signal from the level comparing section and the data stored in the storing section in response to the signal from the fire judging instructing section.

12. A fire alarm system according to claim 11, wherein said data processing section for processing the analog data and which is provided between said detecting section and the storing section, calculates moving averages of the data whenever a predetermined number of analog data are input and outputs the moving averages to the storing section.

13. A fire alarm system according to of claim 12, wherein said change amount is calculated in terms of difference between the respective stored data.

14. A fire alarm system according to claim 13, wherein said respective stored data are consecutive in time.

15. A fire alarm system according to claim 13, wherein said respective stored data are every other data in time.

16. A fire alarm system according to claim 12, wherein said change amount is calculated in terms of quotient divided by a difference between the respective stored data and a difference between detection times of the respective stored data.

17. A fire alarm system according to claim 16, wherein said respective stored data are consecutive in time.

18. A fire alarm system according to claim 16, wherein said respective stored data are every other data in time.