JPH1040478A - Fire detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fire detecting method in which a malfunction is reduced by correctly judging the occurrence of a fire. SOLUTION: A cancel timer 5 is operated for a fixed time by sensing output 1 and 3 of flame and while the cancel timer 5 is operated, the existence of sensing outputs of flame is ignored. After the lapse of fixed time counted by the cancel timer 5, prescribed flame sensing output reception permitting time 6 is proceeded and when there are these sensing outputs of flame with the flame sensing output reception permitting time, it is judged to be a fire so that the external output of warning, etc., can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a fire, and more particularly to a method for reducing malfunctions.

[0002]

2. Description of the Related Art Conventionally, as a fire detection method, a method using an infrared (IR) sensor, a method using an ultraviolet (UV) sensor, or a method using both sensors has been used. Some use an AND output of an IR sensing signal and a UV sensing signal. However, in the detection method using these detectors, in many cases, the signal from the detection unit is output as it is (or AND output) and a fire alarm is issued, but it is not practical because of the frequency of false alarms. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to reduce such a malfunction in a fire detection device. A fire detection signal is transmitted to a new logic circuit of hardware or a new circuit. These problems are solved by processing under software control using a microprocessor or the like by a program including an algorithm.

[0004] That is, one of the fire detection methods of the present invention is to control the external output such as a warning by judging a fire when the flame is detected again within a predetermined time after a lapse of a predetermined time after the flame is detected. In this case, the detection of the flame means the detection of the infrared rays of the flame, the detection of the ultraviolet rays of the flame, or the simultaneous detection of the infrared rays of the flame and the ultraviolet rays.

According to another fire detecting method of the present invention, a cancel timer is operated for a predetermined time in accordance with a flame detection output, and the existence of the flame detection output is ignored during the operation of the cancel timer. A flame detection output reception permission time of a predetermined time is provided later, and when there is a flame detection output within the flame detection output reception permission time, it is determined that a fire has occurred and an external output such as an alarm is controlled. Things. At this time, by setting the cancel timer to zero, it is effective to immediately determine that a fire has occurred at the first flame detection output, and as the flame detection output, an infrared detection output when the flame infrared is detected, It is also effective to use an ultraviolet ray detection output when the ultraviolet ray of the flame is detected, or an AND output in which the infrared ray detection output and the ultraviolet ray detection output are temporally overlapped.

[0006] In general flame detection, a detection signal due to "flame" in the case of fire continues almost intermittently or is continuous. On the other hand, a detection signal when a "flame" other than a fire or an element other than a flame is sensed is often temporary. Therefore, it can be said that erroneous operation of fire detection can be reduced by determining these signals.

Accordingly, in the present invention, the detection signal from the IR sensing means or the UV sensing means is monitored, and if the signal is continuous or intermittently continued within a certain period of time, it is determined that a fire has occurred. In the case of other instantaneous or temporary signals, the function is not determined as a fire, but is canceled and no alarm is output.

The basic operation of the fire detection circuit according to the present invention will be described below. A fixed time width from the first signal when the flame is detected is set as a cancel time, a predetermined time after the lapse of the cancel time is set as a flame detection output acceptance permission time, and other than this, a standby state is set. During the cancel time, external output such as an alarm is not executed even if the sensing signal is continuously present or temporarily generated. If a sensing signal is present, either continuously or temporarily, within the flame sensing output acceptance permitted time, it is accepted and it is determined that there is a fire, and an external output such as an alarm is performed. If there is no detection signal within the flame detection output reception permission time, a standby state is set. By making it possible to arbitrarily set the cancellation time and the flame detection output reception time, it is possible to widely cope with the installation environment and the purpose of use. The output from the IR sensor alone as a flame detection signal,
Either the output from the UV sensor alone or the AND output from the combined use of the IR and UV sensors can be used, and the operation can be greatly stabilized compared to the conventional use of these outputs as they are.

[0009]

Next, an embodiment of the present invention will be described.

FIG. 1 shows a block diagram of a fire detection procedure according to the present invention. FIG. 2 is a time chart for explaining various signal outputs, and the present invention will be described in detail with reference to FIGS. First, when the power of the detection circuit is turned on, the detection circuit enters a standby state. Then, when the UV detector (1) detects "flame", the UV gate timer (2) sets 1
The UV detection output (a) for a second is issued. When the IR detector (3) detects "flame", the IR gate timer (4)
Produces an IR sensing output (b) for one second, but if the UV sensing output (a) and the IR sensing output (b) do not overlap as shown in FIG. 2, the AND output (c) as the next stage is not issued. . That is, it is determined that UV and IR have been generated for different reasons, and the apparatus immediately enters the standby state again.

Next, when the UV sensing output (a) and the IR sensing output (b) are output in an overlapping manner for a time Δt ₁ , it is considered that a flame has been sensed and the AND output (c) is changed to the Δt ₁ . Put out. When the AND output (c) is issued, the cancel timer (5) is activated at the same time. When the timer (5) is activated (d), even if the AND output (c) is present, it is ignored. Note that the set time of the cancel timer (5) may be within 6 seconds when a normal fire is detected, and may be set to 0 second when the cancel timer (5) is not used.

A preset cancel timer (5)
After the time elapses, the output permission signal transmission section (6) sets the flame detection output reception permission time (e) for 1.5 seconds.
That is, the AND operation is performed again within the flame detection output reception permission time (e).
Only when the output (c ') is received, it is determined that a fire has occurred, and a signal of the control output (f) is transmitted from the control output signal transmitting unit (7), and a relay for operating devices such as an alarm and an automatic fire extinguishing device. (8) is driven. If there is no AND output (c ') within the flame sensing output reception permission time (e), the previous AND output (c) is not a fire and returns to the standby state again.

The driving of the relay (8) is normally performed in the following output holding mode. That is, the control output (f)
The relay operation by the latch circuit (9)
As long as the state of N (g) is maintained and the power is not turned off, alarms and the like continue to operate. It is reset when the power is turned off and then turned on again, and returns to the standby state.

As other output modes, there are a pulse mode when a cancel timer is used and a pulse mode when a cancel timer is not used. The operation in the pulse mode when the cancel timer is used is such that the relay operation (h) is simultaneously performed while the control output (f) signal is being output (within 1.5 seconds) as shown by P in FIG. In the case of an actual fire in which the time of one relay operation is short but the AND output is frequently output and the control output (f) is also intermittent, the relay operation is intermittent in response to this. On the other hand, the operation in the pulse mode when the cancel timer is not used is to extend the relay operation time further by 1.5 seconds at that time when there is an AND output (c '') again during the relay operation as described in (h) above. Thus, the relay operation at the time of actual fire is interrupted longer than the above.

[0015]

As described above, according to the present invention, in particular, in a fire detection method using both an IR sensor and a UV sensor, there is almost no malfunction such as an alarm depending on the detection output other than the fire, and the reliability is high. There is a remarkable effect such as obtaining the device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a fire detecting means using the method of the present invention.

FIG. 2 is a time chart of signal output.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultraviolet (UV) detector 2 Ultraviolet gate timer 3 Infrared (IR) detector 4 Infrared gate timer 5 Cancel timer 6 Output permission signal transmission part 7 Control output signal transmission part 8 Relay circuit 9 Latch circuit

Claims (5)

[Claims] 1. A fire detection method comprising: when a flame is detected again within a predetermined time after a lapse of a predetermined time from the time when a flame is detected, determining that a fire has occurred and controlling an external output at the time of an alarm. 2. The fire detecting method according to claim 1, wherein the sensing of the flame is sensing of infrared rays of the flame, sensing of ultraviolet rays of the flame, or simultaneous sensing of infrared rays and ultraviolet rays of the flame. 3. A cancel timer is operated for a predetermined time according to the flame detection output, and the existence of the flame detection output is ignored during the operation of the cancel timer, and the flame detection output for a predetermined time is permitted after a predetermined time has elapsed by the cancel timer. A fire detection method, characterized in that a fire is detected when an output of the flame is detected within the flame detection output acceptance permission time, and an external output such as an alarm is controlled. 4. The fire detection method according to claim 3, wherein a fire is immediately determined by a first flame detection output by setting a cancel timer to zero. 5. The detection output of the flame, the infrared detection output when the infrared of the flame is detected, the ultraviolet detection output when the ultraviolet of the flame is detected, or the temporal overlap of the infrared detection output and the ultraviolet detection output. 5. The fire detection method according to claim 3, wherein the AND output is used.