Early stage fire detecting apparatus

• US 5,673,020 A
• Filed: 03/28/1995
• Issued: 09/30/1997
• Est. Priority Date: 03/30/1994
• Status: Expired due to Fees

• Current Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Original Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Inventors: Okayama, Yoshiaki
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US08/412,272
• Time in Patent Office: 917 Days
• Field of Search: 340/511, 340/512, 340/506, 340/505, 340/514, 340/587, 340/588, 340/510, 340/589
• US Class Current: 340/511
• CPC Class Codes: G08B 17/117 by using a detection device for specific gases, e.g. combustion products, produced by the fire G08B17/103, G08B17/11 take precedence

Abstract

An early stage fire detecting apparatus is arranged such that a fire state is discriminated based on a fire probability output from a signal processing network. The fire probability being prepared in such a manner that outputs from a high sensitivity smoke sensor SS and a smell sensor NS, from which responses can be obtained at the early stage of a fire, are subjected to signal processing. Fire information composed of a value at a given moment of smoke and a difference indicating the increase or decrease of the value at a given moment of the smoke and a value at a given moment of smell and a difference indicating the increase or decrease of the value at a given moment of the smell are input to the signal processing network. The signal processing network outputs the above fire probability based on a table (RAM12) defining a fire probability to be obtained from the above fire information and weighting values (RAM13). With this arrangement, an early stage fire can be detected by explicitly excluding non-fire factors such as tobacco, steam vapor, the smell of coffee, and the like.

Claims

1. An early stage fire detecting apparatus, comprising:

a high sensitivity smoke sensor for detecting a concentration of smoke;

a smell sensor for detecting smell;

input means for subjecting output values from said high sensitivity smoke sensor and said smell sensor to signal processing and obtaining four types of input data composed of a value representing the concentration of smoke at a given moment, a value representing an amount of change in the concentration of smoke over time, a value representing the level of smell at a given moment, and a value representing an amount of change in the level of smell over time;

a signal processing network for calculating a fire probability based on the values of the four types of input data obtained from said input means; and

fire discriminating means for discriminating a fire state based on the fire probability calculated by said signal processing network.

2. An early stage fire detecting apparatus according to claim 1 further comprising:

a memory for storing a table which defines a reference fire probability obtainable for each of a plurality of preset patterns, including a preset non-fire pattern, composed of a combination of values of the four types of input data, said signal processing network having a weighting value for each of the input data so that the reference fire probability defined in the table is obtained when the input data of each preset pattern is input and stored in said memory and the reference fire probability is calculated from the input data using the weighting value.

3. An early stage fire detecting apparatus according to claim 2 wherein said signal processing network includes:

input layers to which the four types of input data are input from said input means;

intermediate layers for obtaining four types of intermediate data by weighting and adding the four types of input data input to said input layers, respectively; and

an output layer for obtaining the fire probability by weighting and adding the four types of intermediate data from said intermediate layers.

4. An early stage fire detecting apparatus according to claim 3 wherein signal lines connect each input layer to each intermediate layer, signal lines connect each intermediate layer to said output layer, and said signal processing network has a weighting value of each signal line between said input layers and said intermediate layers and a weighting value of each signal line between said intermediate layers and said output layer to minimize an error between the value of a fire probability obtained in said output layer when the input data of each preset pattern of the table stored in the said memory is input to said input layers and the value of said reference fire probability defined by the table.

5. An early stage fire detecting apparatus according to claim 1 wherein said high sensitivity smoke sensor is a light scattering type smoke sensor.

6. An early stage fire detecting apparatus according to claim 1 wherein said smell sensor detects scorching smell by a stannic oxide thin film element.

7. An early stage for detecting apparatus according to claim 1 wherein said smell sensor detects fire factor smells and non-fire factor smells.

8. An early stage fire detecting apparatus, comprising:

at least one fire sensor including

a smoke sensor for detecting smoke,

a smell sensor for detecting smell, and

a signal processor for receiving detections from said smoke sensor and said smell sensor and for obtaining a first value of a level of smoke at a given moment, a second value of an amount of change in the level of smoke over time, a third value of a level of smell, and

a fourth value of an amount of change in the level of smell over time;

a fire receiver for receiving said first, second, third and fourth values from said fire sensor through a means for transmitting, said fire receiver including,

a signal processing network for calculating a fire probability based on said first, second, third and fourth values transmitted from said fire sensor, and

fire discriminating means for discriminating a fire state based on the fire probability calculated by said signal processing network.

9. An early stage fire detecting apparatus according to claim 8 wherein said smoke sensor comprises a high sensitivity smoke sensor for detecting a concentration of smoke.

10. An early stage fire detecting apparatus according to claim 9 wherein said high sensitivity smoke sensor comprises a light scattering type smoke sensor.

11. An early stage fire detecting apparatus according to claim 8 wherein said smell sensor comprises a stannic oxide thin film element for detecting a scorching smell.

12. An early stage for detecting apparatus according to claim 8 wherein said smell sensor detects fire factor smells and non-fire factor smells.