JP2004046349A - Fire detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fire detection device that can prevent sending of an erroneous fire signal by removing noise with simple and low-cost means. <P>SOLUTION: The fire detection device comprises detecting means 1 for detecting a fire, noise removing means 2 for removing noise from a detection signal by the detecting means 1, and a receiver 3 for receiving a fire signal sent from the noise removing means 2. The noise removing means 2 use an AND gate 4, where of two inputs a and b, one input b accepts the detection signal as it is and the other a accepts the detection signal via a delay circuit 5, and the AND gate 4 outputs the fire signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fire detection device capable of transmitting a fire signal from which noise has been removed to a receiver.
[0002]
[Prior art]
Conventionally, as shown in FIG. 6, a detecting means 1 for detecting a fire, a noise removing means 2 for removing noise from a signal detected by the detecting means 1, and a receiving means for receiving a fire signal transmitted from the noise removing means 2 A fire detection device including the device 3 is known. This fire detection device is used in an automatic fire alarm system. When a fire is detected at a terminal 9 that detects and outputs a fire, a detection signal is input to a microcomputer 10 and the microcomputer 10 determines whether or not the fire is detected. Is determined, the microcomputer 10 determines the fire, and a fire signal is transmitted from the terminal 9 to the receiver 3.
[0003]
In this case, the microcomputer 10 is used as the noise removing unit 2 that removes noise from the detection signal from the detecting unit 1. Even if an erroneous signal is input as a detection signal to the microcomputer 10 due to noise or the like, the microcomputer 10 is used. It is determined by the algorithm of 10 whether or not a fire occurs, and a fire signal is transmitted from the terminal 9 to the receiver 3 only when a real fire occurs. For example, there is a noise removal processing method of a fire detecting device as disclosed in Japanese Patent Application Laid-Open No. 2001-101543. Here, an MPU (microprocessor unit) is provided with a noise detection unit, a noise removal processing unit, a fire determination unit, a memory, and the like, so that malfunction due to the influence of noise is prevented.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional technique, the cost is increased because the microcomputer 10 is used as the noise removing means 2, and the processing program in the microcomputer 10 is complicated, so that the method of removing the noise is as follows. There was a problem that it became difficult and large.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in order to solve all the problems in the above-mentioned conventional technology, and an object thereof is to eliminate noise by simple and inexpensive means to prevent an erroneous fire signal from being transmitted. It is an object of the present invention to provide a fire detection device capable of performing the above.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a fire detecting device for detecting a fire, a noise removing device for removing noise from a signal detected by the detecting device, and a receiving device for receiving a fire signal transmitted from the noise removing device. A fire detection device comprising an AND gate as a noise removing means, one of two inputs to the AND gate receives a detection signal as it is, and the other inputs a detection signal through a delay circuit. As an input, a fire signal is output from the AND gate.
[0007]
Therefore, in this case, of the two inputs of the AND gate as the noise removing means, one receives the detection signal as it is and the other receives the detection signal through the delay circuit, so that the detection signal is an erroneous signal. At one time, this signal is of a short duration, and when it is input through the delay circuit, there is no signal previously input as it is, and no fire signal is output from the AND gate. Also, if the detection signal is a true signal due to a fire, this signal will be for a long time, and the signal that has been input as it was when it was input through the delay circuit will still continue. , A fire signal is output from the AND gate.
[0008]
As described above, while the false detection signal due to the noise is short, the detection signal when a fire is actually detected is not short, so that by appropriately setting the delay time of the delay circuit, the false detection signal can be obtained. The detected signal is canceled and the fire signal is not transmitted to the receiver. Conversely, if the fire signal is the true detection signal, the fire signal is transmitted to the receiver. Here, noise is easily removed by an AND gate that is cheaper than a microcomputer, and the transmission of erroneous fire signals is reduced, thereby preventing malfunction due to the influence of noise.
[0009]
According to a second aspect of the present invention, there is provided a fire detecting apparatus according to the first aspect, wherein a circuit having a resistor, a capacitor, and a buffer on an input side thereof is used as the delay circuit. Is what you do.
[0010]
Therefore, in this case, in particular, since the delay circuit has a buffer, a resistor, and a capacitor, noise removal and waveform shaping of the detection signal are performed in the buffer, and thereafter, charge and discharge are performed by the resistor and the capacitor. The detection signal can be delayed. At that time, the detection signal having the shaped waveform is input, so that the charging and discharging time can be calculated more accurately with the resistor and the capacitor, and the delay time in the delay circuit can be easily set.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a fire detecting device according to an embodiment of the present invention. The fire detecting device includes a detecting means 1 for detecting a fire, a noise removing means 2 for removing noise from a signal detected by the detecting means 1, and a receiver 3 for receiving a fire signal transmitted from the noise removing means 2. , Is provided. An AND gate 4 is used as the noise removing means 2. One of the two inputs a and b to the AND gate 4 receives the detection signal as it is b, and the other inputs the detection signal through the delay circuit 5 to the input a. In this case, a fire signal is output from the AND gate 4.
[0012]
This fire detection device is used in an automatic fire alarm system or the like. When a fire is detected at a terminal 9 that detects and outputs a fire, a detection signal is transmitted to the noise removing means 2 and the terminal 9 is connected to the terminal 9. Is transmitted to the receiver 3 as a fire signal. Here, the terminal 9 is like an analog fire detector, and one or a plurality of terminals are connected to the receiver 3 such as a disaster prevention receiver via a transmission line or the like.
[0013]
The detection means 1 for detecting a fire detects smoke, temperature, and the like. For example, in the case of a photoelectric type for detecting smoke due to a fire, a light emitting unit is driven to emit light at a constant cycle, and the light emitting unit is driven. The scattered light or attenuated light due to the smoke of the light is received by the light receiving unit, converted into an electric signal, and detected as a smoke detection signal corresponding to the smoke density, that is, a so-called smoke analog value. The detection signal detected by the detection means 1 is transmitted to the AND gate 4.
[0014]
Here, the signal is transmitted to the AND gate 4 via two paths which are parallel circuits, and a delay circuit 5 is provided on one path. The detection signal transmitted through the delay circuit 5 of this one path is delayed by a predetermined time by the delay circuit 5 and input to the AND gate 4. In the other path, the detection signal detected by the detection means 1 is directly input to the AND gate 4b. At that time, it is preferable that the signal waveform is shaped by the buffer in any path. Then, the AND gate 4 transmits a fire signal to the receiver 3 only when the signal waveforms of the inputs a and b are both at a certain level or higher.
[0015]
That is, as shown in FIG. 2, when an erroneous detection signal due to noise is input, the AND gate 4 does not output a fire signal, and as shown in FIG. 3, when a detection signal due to a true fire is input. , The AND gate 4 outputs a fire signal. In the case of FIG. 2, since an erroneous detection signal due to noise is relatively short, when the input a delayed by the delay circuit 5 enters, the previous input b does not exist, so that the AND gate In No. 4, no fire signal is output. In the case of FIG. 3, since the detection signal due to a real fire has a certain length, even when the input a delayed by the delay circuit 5 is input, the input b is continued as it is. , The AND gate 4 outputs a fire signal.
[0016]
The delay time t in the delay circuit 5 may be set as appropriate, and is set to a time for discriminating between a real fire and a noise, and a delay of about several seconds. Time t is sufficient. Here, if the delay time t is set too short, it is difficult to discriminate and remove noise as noise. Conversely, if the delay time t is set too long, a fire is surely determined. It is not suitable for reporting an emergency.
[0017]
Next, a specific example of the delay circuit 5 is shown in FIG. 4, and this specific example corresponds to claim 2. The delay circuit 5 is provided on a path on the input a side of the AND gate 4, and is a circuit having a resistor 7, a capacitor 8, and a buffer 6 on the input side of these. In this case, the signal waveform shown in FIG. 5A is obtained at the portion shown in FIG. 4A, and the signal waveform shown in FIG. 5B is obtained at the portion shown in FIG. In this case, the waveform is shaped by the buffer 6 so as to correspond to the reference threshold value, and noise is removed from the signal waveform. Thereafter, charge and discharge are performed by the resistor 7 and the capacitor 8, whereby the signal is delayed, and a signal waveform as shown in FIG. 5 (3) is obtained at the portion of FIG. 4 (3).
[0018]
On the other hand, in the path on the input b side of the AND gate 4, the detection signal is directly input to the AND gate 4 without delay, but also in this case, the signal waveform may be shaped by the buffer. Preferably, in this case, the signal waveform shown in FIG. 5 (4) is obtained at the portion shown in FIG. 4 (4). By providing the buffer 6 in the delay circuit 5 at a position before branching into a parallel circuit, the signal waveforms on both paths may be shaped together.
[0019]
Then, the AND gate 4 transmits a fire signal to the receiver 3 only when the signal waveforms of the inputs a and b are both at a certain level or higher. FIG. 5 shows a case where an erroneous detection signal due to noise is input. In this case, as shown in FIGS. 5 (3) and (4), the signal waveforms of the inputs a and b exceed a certain level at the same time. Therefore, the fire signal is not transmitted from the AND gate 4, that is, the signal waveform is as shown in FIG. 5 (5) at the portion of FIG. 4 (5).
[0020]
Therefore, in the fire detection device of this embodiment, one of the two inputs a and b of the AND gate 4 as the noise removing means 2 receives the detection signal as it is b and the other receives the detection signal through the delay circuit 5. Since the detection signal is an erroneous signal, the signal is of a short time, and when the detection signal is input through the delay circuit 5, the signal input earlier as it is is No fire signal is output from the AND gate 4. When the detection signal is a true signal due to a fire, the signal is extended for a long time, and when the signal is input through the delay circuit 5, the signal previously input as it is is still continued. As a result, a fire signal is output from the AND gate 4.
[0021]
As described above, while a false detection signal due to noise is a short time, a detection signal when a fire is truly detected is not a short time. Therefore, by appropriately setting the delay time of the delay circuit 5, the former can be achieved. Such an erroneous detection signal is canceled and the fire signal is not transmitted to the receiver 3. Conversely, if the detection signal is a true detection signal such as the latter, the fire signal is transmitted to the receiver 3. Will be sent. Here, the noise is easily removed by the AND gate 4 which is less expensive than the conventional microcomputer, the erroneous fire signal transmission is reduced, and the malfunction due to the influence of the noise is prevented.
[0022]
Further, in the fire detection device of this embodiment, if the delay circuit 5 has the resistor 7 and the capacitor 8 and the buffer 6 on the input side thereof, the buffer 6 can remove the noise of the detection signal and shape the waveform. After the detection, the charge and discharge are performed by the resistor 7 and the capacitor 8, and the detection signal can be delayed. At that time, the detection signal of the shaped waveform is input, so that the charging and discharging time can be calculated more accurately in the resistor 7 and the capacitor 8, and the delay time t in the delay circuit 5 is set. It is easy to do.
[0023]
【The invention's effect】
As described above, in the fire detecting device according to the first aspect of the present invention, the erroneous detection signal is canceled, and the fire signal is transmitted to the receiver only when the detection signal is a true detection signal. The noise is easily removed by the AND gate, and the transmission of the erroneous fire signal is reduced, and the malfunction due to the influence of the noise is prevented.
[0024]
Further, in the fire detection device according to the second aspect of the present invention, in particular, after the noise removal and the waveform shaping of the detection signal are performed, the charge and discharge of the charge are performed to delay the detection signal. The charge / discharge time can be calculated more accurately, and the delay time in the delay circuit can be easily set.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a fire detection device according to an embodiment of the present invention.
FIG. 2 is a signal waveform diagram showing an input signal and an output signal at an AND gate when the signal is a noise signal in the fire detection device.
FIG. 3 is a signal waveform diagram showing an input signal and an output signal at an AND gate when the signal is a true signal in the fire detection device.
FIG. 4 is a circuit diagram showing a specific example of a delay circuit in the fire detection device.
FIG. 5 is a signal waveform diagram showing signal waveforms at (1) to (5) in FIG. 4;
FIG. 6 is a block diagram showing a conventional fire detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Detection means 2 Noise removal means 3 Receiver 4 AND gate 5 Delay circuit 6 Buffer 7 Resistance 8 Capacitor

Claims (2)

A fire detection device comprising: a detection unit that detects a fire; a noise removal unit that removes noise from a signal detected by the detection unit; and a receiver that receives a fire signal transmitted from the noise removal unit, An AND gate is used as a noise removing means. Of the two inputs to the AND gate, one receives the detection signal as it is, and the other receives the detection signal through a delay circuit. Fire detection device that can output 2. The fire detecting device according to claim 1, wherein a circuit having a resistor, a capacitor, and a buffer on an input side thereof is used as the delay circuit.

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