JPH05120580A - Complex fire sensor - Google Patents

Abstract

PURPOSE:To provide the fire sensor which functions to detect a fire and is increased in sensitivity only when watching out to eliminate misalarming. CONSTITUTION:This fire sensor has a smoke sensing circuit 101 which senses smoke, a flame detecting circuit 11 which detects flames, and a timer circuit 12 which counts a specific time after the flame detecting circuit 11 detects the flames. Further, this sensor has a comparing circuit 13 which increases the sensitivity to the smoke by decreasing the threshold value until the timer circuit 12 counts up to the specific time after the flame detecting circuit 11 detects the flames. Furthermore, the sensor is equipped with a fire signal sending circuit 103 which outputs a fire alarm signal once receiving the fire decision signal outputted by the comparing circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined fire detector having a smoke or heat detector and a flame detector.

[0002]

2. Description of the Related Art FIG. 7 shows a configuration example of a conventional fire detector 100. The smoke detection circuit 101 detects smoke, converts it into an electric signal corresponding to the smoke density as shown in FIG. 6, and sends it to the comparison circuit 102. In the comparison circuit 102, this electric signal is compared with a preset threshold value, and if the electric signal is equal to or higher than the threshold value, a fire determination signal is sent to the fire signal reporting circuit 103, and the fire signal reporting circuit 103 The fire signal is issued in response to the fire discrimination signal. This figure shows a smoke detector, but the heat sensing type for sensing temperature and temperature gradient, and the flame sensing type for detecting infrared rays and ultraviolet rays emitted from the flame have the same configuration. However, in the fire detector 100 as described above, the threshold value of the comparison circuit 102 is lowered to increase the sensitivity in order to detect a fire early. Smoke, and in the case of a flame detector, it was also detected by the flame of a smoking lighter, and there was a problem that false alarms increased. In particular, assuming a fire is set at a store,
In many cases, arson is caused by throwing paper scraps that have been lit with a match or a lighter into the trash can, or the futon is lit, but the characteristic of these fires is that the smoke continued to smolder for a considerable time. After that, the fire suddenly went up,
In many cases, it is already late. However, since the flame does not come out when the smoke is smoldering, if you try to detect the flame when using a light detector etc. with a flame detector, it will detect even the flame caused by smoking that is not related to the fire. After all, there was a problem such as many false alarms.

[0003]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and has a function of detecting a flame and increases sensitivity only when caution is required so that false alarms do not occur. The purpose is to provide a combined fire detector capable of

[0004]

The present invention according to claim 1, which is proposed to achieve the above object, provides a smoke detection circuit for detecting smoke, a flame detection circuit for detecting flame, and a flame detection circuit. A timer circuit that counts the time since and a comparison circuit that raises the sensitivity to smoke for a certain time after detecting the flame,
It is configured to include a fire signal reporting circuit. The present invention according to claim 2 provides a heat sensing circuit for sensing heat, a flame sensing circuit for sensing flame, a timer circuit for counting time after sensing flame, and a constant value after sensing flame. Only time
It is configured to include a comparison circuit for increasing sensitivity to heat and a fire signal issuing circuit. According to another aspect of the present invention, a smoke detecting circuit for detecting smoke, a heat detecting circuit for detecting heat, a flame detecting circuit for detecting flame, and a timer circuit for counting time after detecting flame. And a smoke comparison circuit that increases the sensitivity to smoke for a certain period of time after detecting a flame, a thermal comparison circuit that increases the sensitivity to heat for a certain period of time after detecting a flame, and a fire signal reporting circuit. It has been configured. According to a fourth aspect of the present invention, in addition to the respective parts according to the first aspect, the second aspect, or the third aspect, a sensitivity control circuit that gradually increases the sensitivity to smoke or heat for a predetermined time after detecting the flame. It is configured with.

[0005]

In the fire detector according to the first aspect of the present invention, when the flame detection circuit detects a flame, the timer circuit is activated and the threshold value of the comparison circuit is lowered at the same time, so that the sensitivity to smoke is increased. Therefore, even low-density smoke can be detected and early detection of a fire becomes possible. However, when the timer circuit times out, the threshold value of the comparison circuit returns to the original level, so that a malfunction such as smoking is prevented. In the fire detector according to the second aspect of the present invention, when the flame detection circuit detects a flame, the threshold value of the comparison circuit is lowered at the same time when the timer circuit is activated, so that the sensitivity to heat is increased. Therefore, even when the temperature rise is low or the temperature gradient is gentle, it can be detected and the fire can be detected early. However, when the timer circuit times out, the threshold value of the comparison circuit returns to the original level, and malfunction is prevented. In the fire detector of the present invention as set forth in claim 3, when the flame detection circuit detects a flame, the timer circuit is activated, and at the same time, the threshold values of the smoke and heat comparison circuits are both lowered, so that the smoke and heat can be prevented. The sensitivity is increased. Therefore, it is detected even when low-density smoke is detected, when the temperature rise is low, or when the temperature gradient changes gently,
It enables early detection of fire. However, when the timer circuit times out, the threshold values of the smoke and heat comparison circuits both return to their original levels, so malfunctions are prevented. In the fire detector of the present invention as set forth in claim 4, after the flame detection circuit detects the flame, the time until the timer circuit times up the predetermined time is the smoke or heat comparison circuit or the two comparison circuits. The threshold is lowered to increase sensitivity to smoke and heat. Then, the threshold value of the smoke / heat comparison circuit or the two comparison circuits is further decreased step by step within a predetermined time until the timer circuit times out, so that the smoke / heat, or the smoke / heat is increased with time. Sensitivity to fire is gradually increased, and fires can be detected even faster. However, when the timer circuit times out, the threshold values of the smoke and heat comparison circuits both return to their original levels, so malfunctions are prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the fire detector of the present invention as defined in claim 1, and the same parts as those in the prior art are designated by the same reference numerals. Hereinafter, the configuration of the fire detector 10 of the present invention will be described together with the operation based on FIG.
When the flame detection circuit 11 detects a flame, the timer circuit 12 is activated and the transistor TR becomes conductive, so that the threshold value Vref of the comparison circuit 13 becomes Vcc × (R2 +).
R3) / (R1 + R2 + R3) to Vcc × R2 / (R1 +
R2) is switched and set. By appropriately selecting R1, R2 and R3, the threshold value Vref of the comparison circuit can be lowered to an arbitrary value, and the sensitivity to smoke is increased.
When the smoke sensitivity is increased, the smoke detection circuit 101
Even if the electric signal from the device corresponds to a low smoke concentration, the threshold value Vref is lowered in the comparison circuit 13, so the threshold value is easily exceeded, and the comparison circuit 13 outputs the fire determination signal to the fire signal issuing circuit 103. Send to. When the fire signal issuing circuit 103 receives this fire discrimination signal, the fire signal is issued. With such a configuration, if the detected flame is due to smoking etc. and not due to fire,
The smoke is not sensed, and after the timer circuit 12 has counted a certain time, the sensitivity to the smoke is returned to the normal value (the threshold value Vref of the comparison circuit 13 is raised). In this embodiment, the transistor TR and the resistors R1 to R3 are used as a method of changing the threshold Vref of the comparison circuit 13, but other methods are also possible.

FIG. 2 shows an embodiment of the fire detector of the present invention as defined in claim 2. The same parts as those in the prior art are designated by the same reference numerals. Hereinafter, the configuration of the fire detector 20 of the present invention will be described together with the operation based on FIG.
When the flame detection circuit 11 detects a flame, the timer circuit 12
Is activated and the transistor TR becomes conductive, the threshold value Vref of the comparison circuit 13 becomes Vcc × (R5
+ R6) / (R4 + R5 + R6) to Vcc × R5 / (R4
+ R5) is switched and set. By appropriately selecting R4, R5, and R6, the threshold value Vref of the comparison circuit 13 can be lowered to an arbitrary value, and the sensitivity to heat is increased. In the state where the sensitivity to heat is increased, the threshold value Vref is lowered in the comparison circuit 13, so that the threshold value can be easily set even when the electric signal from the heat sensing circuit 21 has a relatively low temperature rise or a gentle temperature gradient. Beyond, comparison circuit 1
3 sends a fire discrimination signal to the fire signal issuing circuit 103. When the fire signal issuing circuit 103 receives this fire discrimination signal, the fire signal is issued. In such a configuration, if the detected flame is due to smoking or the like and not due to a fire, the temperature rise is not sensed, and after the timer circuit 12 counts a certain time, the sensitivity to heat is usually The value is returned to the value (the threshold value Vref of the comparison circuit 13 is increased). The heat sensing circuit 21 may be of a constant temperature type that senses a temperature rise to a certain level or a differential type that senses a temperature gradient as described above.
The configuration other than 1 is the same.

FIG. 3 shows an embodiment of the fire detector 30 of the present invention as defined in claim 3. In this example, in addition to the detection of flame, a combined structure for detecting smoke and heat is provided. Is becoming The same parts as those in the prior art of the circuit are denoted by the same reference numerals. Also in this embodiment, the flame detection circuit 11 and the timer circuit 12
Also, the configuration is such that the fire signal issuing circuit 31 is shared, and the operation is the same as the description of FIGS. In such a fire detector, there are two possible methods for processing the signals from the smoke comparison circuit 32 and the heat comparison circuit 33 in the fire signal reporting circuit 31. That is, a method of issuing a fire signal only when receiving a detection signal from both of the comparison circuits, and a method of issuing a fire signal when receiving a detection signal from either of the comparison circuits, either will do. Further, although the timer circuit 12 is shared, separate timer circuits may be provided to set the set time individually, and the set values of the comparison circuit may be different from each other.

FIG. 4 shows the construction of an embodiment of the fire detector 40 according to the present invention as set forth in claim 4, and FIG. 5 shows a time chart of a comparison circuit of the embodiment, which is a prior art. The same parts as those in are denoted by the same reference numerals. Below, in FIG.
The operation will be described based on 5. Usually, the sensitivity to smoke or heat is kept at the conventional value. First, flame detection circuit 1
When 1 detects the flame, when the timer circuit 41 is activated,
As shown in FIG. 5, the sensitivity control circuit 42 gradually lowers the threshold value of the comparison circuit 13 at predetermined time intervals of 0, T1, and T2, and gradually raises the sensitivity to smoke. When the smoke sensitivity gradually increases, the smoke detection circuit 1
Even if the electric signal from 01 corresponds to a low smoke density, the threshold value Vref is lowered stepwise in the comparison circuit 13, so the threshold value is easily exceeded, and the comparison circuit 13 sends the fire determination signal to the fire signal. The fire signal is issued to the alarm circuit 103, and the fire signal alarm circuit 103 receives the fire discrimination signal and issues a fire signal. In such a configuration, if the detected flame is due to smoking or the like and not due to a fire, the smoke is not sensed, and after the timer circuit 41 counts the constant time T3, the sensitivity to the smoke becomes the normal value. Will be returned. Although the present embodiment has described the example using the smoke sensing circuit, a heat sensing circuit may be used, and the threshold values of the smoke and heat comparing circuits 13 may be used in accordance with the activation of the timer circuit 41 by using both. May be lowered stepwise. In each of the above embodiments, only one sensing circuit and one sensing circuit are used.
A plurality of them may be used, and various methods of processing a plurality of detection signals in the fire signal issuing circuit are conceivable.

[0010]

As described above, the first, second, third aspects are provided.
According to the present invention described in 4, it is possible to increase the sensitivity to smoke and heat only when caution is required in accordance with the detection of the flame so that false alarms do not occur.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention according to claim 1.

FIG. 2 is a configuration diagram of an embodiment of the present invention according to claim 2;

FIG. 3 is a configuration diagram of an embodiment of the present invention according to claim 3;

FIG. 4 is a configuration diagram of an embodiment of the present invention according to claim 4;

FIG. 5 is a time chart of the comparison circuit shown in FIG.

FIG. 6 is a graph showing a relationship between smoke concentration and an electric signal in the smoke detection circuit.

FIG. 7 is a diagram showing a configuration example of a conventional fire detector.

[Explanation of symbols]

 10, 20, 30, 40 ... Fire detector 11 ... Flame detection circuit 12, 41 ... Timer circuit 13 ... Comparison circuit 21 ... Heat detection circuit 31, 103 ... Fire signal emission Report circuit 32 ... Smoke comparison circuit 33 ... Thermal comparison circuit 42 ... Sensitivity control circuit 101 ... Smoke detection circuit TR ... Transistors R1 to R13 ... Resistance Vcc ... Power supply voltage Vref. ..Thresholds of comparison circuits

Claims (4)

[Claims] 1. A smoke detection circuit for detecting smoke, a flame detection circuit for detecting flame, a timer circuit for counting a predetermined time after the flame detection circuit detects the flame, and a flame detection circuit for detecting the flame. After that, while the timer circuit measures the predetermined time, the comparison circuit that lowers the threshold value and increases the sensitivity to smoke, and the fire signal notification that outputs the fire warning signal in response to the fire discrimination signal output from this comparison circuit A combined type fire detector characterized by comprising a circuit. 2. A heat detecting circuit for detecting heat, a flame detecting circuit for detecting a flame, a timer circuit for counting a predetermined time after the flame detecting circuit detects the flame, and a flame detecting circuit for detecting the flame. After that, while the timer circuit measures the predetermined time, the comparison circuit that lowers the threshold value and increases the sensitivity to heat, and the fire signal notification that outputs the fire notification signal in response to the fire discrimination signal output from this comparison circuit A combined type fire detector characterized by comprising a circuit. 3. A smoke detecting circuit for detecting smoke, a heat detecting circuit for detecting heat, a flame detecting circuit for detecting flame, a timer circuit for counting a predetermined time after detecting flame, and detecting flame. After that, while the timer circuit measures the predetermined time, the smoke comparison circuit and the heat comparison circuit that lower the thresholds and increase the sensitivity to smoke and heat, and the fire output from these smoke comparison circuit and the heat comparison circuit. A composite fire detector, comprising: a fire signal issuing circuit that receives a discrimination signal and outputs a fire alarm signal. 4. The sensitivity to smoke and heat is also increased stepwise by decreasing the threshold values of the smoke comparison circuit and the heat comparison circuit individually or simultaneously stepwise for a predetermined time after the timer circuit is activated. Equipped with a sensitivity control circuit,
The composite fire sensor according to claim 1, 2 or 3.