JPH05225467A - Flame detector - Google Patents

Abstract

PURPOSE:To considerably reduce the current consumption with respect to the flame detector which detects ultraviolet rays radiated from flames by a discharge tube to report a fire. CONSTITUTION:A power switch circuit Q1 is provided which turns on/off the power supply to the circuit part which includes an oscillating circuit 4 and a boosting circuit 5 and has a large current consumption, and the voltage applied to a discharge tube 8 is monitored by a voltage detecting circuit 7, and the power switch circuit Q1 is turned off to stop the power supply when the detected voltage is in a prescribed level or higher, but the power switch circuit Q1 is turned on to supply the power when the detected voltage is lower than the prescribed level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame detector for detecting a fire by detecting ultraviolet rays emitted from a flame by a discharge tube.

[0002]

2. Description of the Related Art Conventionally, as a flame detecting device of this type, there is one shown in FIG. 4, for example. In FIG. 4, 1 is a depolarizing circuit using a diode bridge that depolarizes the connection polarity of the signal line for power supply from the receiver to terminals L and C, 2 is a switching circuit such as SCR, and 3 is a constant voltage circuit. 4, an oscillator circuit, 5 a booster circuit, 6 a rectifier circuit, 8 a discharge tube, 9 a signal processing circuit, C1 a smoothing capacitor, C
2 is a capacitor for storing discharge charge, R1 is a charging resistor, R
2 is a discharge load resistance.

Power is constantly supplied from the constant voltage circuit 3 to the oscillator circuit 4, the booster circuit 5, the rectifier circuit 6 and the signal processing circuit 9, and the booster circuit 5 is driven by the oscillation pulse from the oscillator circuit 4. Rectifier circuit 6
Is converted into a DC voltage by means of a resistor R1 to charge the capacitor C2, and a high DC voltage of about 330 V is applied to the discharge tube 8.

In the event of a fire, when ultraviolet rays emitted from the flame enter the discharge tube 8, the discharge tube 8 starts to discharge, the electric charge of the capacitor C2 is discharged, and a discharge current flows through the resistor R2. Since the capacitance of the capacitor 2 is small, on the order of hundreds to thousands of pF, and the impedance of the charging resistor R1 is relatively high, the electric charge of the capacitor C2 immediately disappears, and the applied voltage drops, so that the discharge is stopped, resulting in the discharge. A voltage pulse is generated across the load resistor R2. If ultraviolet rays from the flame are continuously incident, the discharge tube 8 is discharged again after charging the capacitor C2, and this is repeated.

The signal processing circuit 9 inputs the pulse voltage generated across the discharge load resistor R2 and counts it. When a count value of a predetermined number or more is obtained in a predetermined time, it is judged as a fire, and the switching circuit 2 is triggered. Then, the fire detection signal is sent out by short-circuiting the terminals L and C to a low impedance and sending an alarm current to the signal line that also serves as a power source from the receiver.

[0006]

However, such a conventional flame detecting device has a problem that the current consumption is larger than that of a smoke detector, a heat detector, or the like. Therefore, a low current consumption device such as a C-MOS is used for the oscillator circuit 4 and the booster circuit 5 which are always in a driving state. Idle current flows through the bias circuit of No. 5, and there is a limit to reduction of current consumption.

For this reason, the number of flame detection devices that can be connected to the power source / signal line from the receiver is set so that the alarm current at the time of fire detection can be clearly distinguished from the total current consumption of the plurality of flame detection devices. However, since the number of connections per line is small, a large number of lines must be extracted from the receiver and distributed, which causes a problem that the facility configuration becomes complicated and the cost increases.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a flame detection device using a discharge tube capable of significantly reducing current consumption.

[0009]

To achieve this object, the present invention is constructed as follows. The reference numerals in the drawings of the embodiments are also shown. First, the present invention relates to a discharge tube 8 that detects and discharges ultraviolet rays or the like emitted from a flame, and a discharge tube 8
Booster circuit 5 for generating a high voltage applied to
And a capacitor C2 that stores the discharge charge of the discharge tube 8 that is charged by the output voltage of the booster circuit 8 and the oscillation circuit 4 that drives the
And a signal processing circuit 9 that counts the pulses obtained for each discharge of the discharge tube 8 and judges a fire when a pulse count value of a predetermined value or more is obtained.

According to the present invention regarding such a flame detection device, a power supply switch circuit Q1 (or Q1, Q2) for turning on / off the power supply to a circuit portion having a large current consumption including the oscillation circuit 4 and the booster circuit 5. When the detected voltage is equal to or higher than a predetermined level, the power switch circuit Q1 is turned off to stop the power supply, and when the detected voltage is lower than the predetermined level, the power switch circuit Q1 is turned on to turn on the power. And a voltage detection circuit 7 for supplying the voltage are provided.

The present invention also provides an oscillator circuit 4 and a booster circuit 5.
Turn on the power supply to the circuit part with high current consumption, including
First power switch circuit Q1 (or Q1, Q2) to turn off
The voltage applied to the discharge tube 8 is monitored. When the detected voltage is equal to or higher than a predetermined level, the power switch circuit Q1 is turned off to stop the power supply, and when the detected voltage is lower than the predetermined level, the first power switch circuit Q1 is turned on. Voltage detection circuit 7 for supplying power
In addition, a second power switch circuit Q3 for turning on / off the power supply to the signal processing circuit 9 and a second power switch circuit Q3 for a predetermined time when a discharge pulse is obtained by discharging the discharge tube 8. A timer circuit (one-shot multivibrator circuit) 10 for supplying power to the signal processing circuit 9 is provided.

[0012]

According to the flame detecting apparatus of the present invention having such a configuration, the consumption including the oscillating circuit and the boosting circuit is performed only when the high DC voltage applied to the discharge tube for detecting the ultraviolet rays becomes lower than the predetermined voltage. Supplying power to the circuit part with large current,
When the DC high voltage applied to the discharge tube is equal to or higher than the predetermined voltage, the power supply to the circuit portion consuming large current is stopped.

Therefore, the current consumption of the flame detection device in the steady monitoring state is suppressed to an extremely weak current, the number of devices that can be connected per line can be significantly increased, and the emergency battery provided in the receiver can be increased. The capacity of can be reduced. Further, the power supply to the signal processing circuit for judging the fire by counting the discharge pulses of the discharge tube is performed only for a predetermined time after the discharge pulse is obtained, so that the current consumption in the steady monitoring state can be further reduced. ..

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment showing one embodiment of the present invention. In FIG. 1, 1 is a depolarizing circuit using a diode bridge, 2 is a switching circuit using SCR, 3 is a constant voltage circuit, 4 is an oscillating circuit, 5 is a boosting circuit, 6
Is a rectifier circuit, 8 is a discharge tube, and 9 is a signal processing circuit. A smoothing capacitor C1 is provided at the output stage of the constant voltage circuit 3. The oscillation circuit 4 generates an oscillation pulse of a predetermined frequency by the booster circuit 5.
Supply and drive.

The booster circuit 5 is driven by the oscillation pulse from the oscillator circuit 4 and generates a boosted pulse voltage.
The rectifier circuit 6 rectifies the boost pulse voltage of the boost circuit 5 to generate a high DC voltage. The DC high voltage of the rectifier circuit 6 is charged in the capacitor C2 via the charging resistor R1, and the charging voltage of the capacitor C2 is supplied to the anode of the discharge tube 8.

A discharge load resistor R is provided on the cathode side of the discharge tube 8.
2 is connected, and the voltage pulse generated across the discharge load resistor R2 by the discharge current flowing in the discharge operation of the discharge tube 8 when receiving ultraviolet rays from the flame is input to the signal processing circuit 9. Although such a circuit configuration is the same as that of the conventional device shown in FIG. 4, in addition to this, in the present invention, the oscillator circuit 4 is used.
A PNP transistor Q1 as a power switch circuit is provided on the power supply line from the constant voltage circuit 3 to the booster circuit 5.

Further, a voltage detection circuit 7 is provided as means for controlling the supply of power to the oscillation circuit 4 and the booster circuit 5 by turning on and off the transistor Q1. The voltage detection circuit 7 detects the charging voltage of the capacitor C2 applied to the discharge tube 8, and if the detected voltage is a predetermined value or more, turns off the transistor Q1 to stop the power supply to the oscillation circuit 4 and the booster circuit 5. When the detected voltage becomes lower than a predetermined value, the transistor Q1 is turned on to supply power to the oscillation circuit 4 and the booster circuit 5.

As such a voltage detection circuit 7, an appropriate circuit means such as a Zener diode, a comparator, a PUT can be adopted. Next, the operation of the embodiment shown in FIG. 1 will be described. First, in the flame detection device of FIG. 1, the terminals L and C are connected to the power source / signal line drawn from the receiver,
When power is supplied from the receiver, the polarity is adjusted by the depolarizing circuit 1 and the power supply voltage stabilized at a predetermined voltage by the constant voltage circuit 3 is supplied to each circuit section.

When the power is turned on, the charging voltage of the capacitor C2 is 0 volt, so the voltage detecting circuit 7 turns on the transistor Q1. When the transistor Q1 is turned on, power is supplied from the constant voltage circuit 3 to the oscillator circuit 4 and the booster circuit 5, the oscillator circuit 4 starts an oscillating operation, and the booster circuit 5 generates a boost pulse in response to the oscillation output. A high DC voltage of about 330 V is output from the rectifying circuit 6, and the charging of the capacitor C2 is started via the charging resistor R1.

When the voltage detecting circuit 7 determines that the charging voltage of the capacitor C2 has risen and reaches the predetermined voltage level, the voltage detecting circuit 7 turns off the transistor Q1.
Therefore, the power supply to the oscillation circuit 4 and the booster circuit 5 is stopped. After that, when the voltage detection circuit 7 detects that the charging voltage of the capacitor C2 spontaneously discharges due to circuit leakage or the like and gradually decreases, and the charging voltage drops below a predetermined voltage level, the transistor Q1 is turned on and the oscillation circuit 4 Then, power is supplied to the booster circuit 5 and the capacitor C2 is charged again until it reaches a predetermined voltage level. As a result, the high DC voltage applied to the discharge tube 8 can be maintained within a predetermined voltage range in which discharge is possible when receiving ultraviolet rays from the flame.

When the discharge tube 8 detects the ultraviolet rays emitted from the flame due to a fire, electrons are emitted from the cathode surface of the discharge tube 8 and are attracted to the anode to which a high voltage is applied. A large number of secondary electrons are generated by colliding with gas molecules inside 8, and a large current suddenly flows to be in a discharge state. The discharge current flowing by the discharge operation of the discharge tube 8 is supplied from the capacitor C2.
Has a small value on the order of hundreds to thousands of pF, and has a large resistance value of the charging resistor R1,
The voltage of the capacitor C2 sharply drops due to the discharge operation of the discharge tube 8, and the discharge of the discharge tube 8 stops.

Therefore, the discharge current of the discharge tube 8 flows through the discharge load resistor R2 for a short time, and a pulse voltage is generated at both ends by the discharge current. On the other hand, the voltage of the capacitor C2 drops due to the discharge of the discharge tube 8, and when this voltage drop is detected by the voltage detection circuit 7, the transistor Q1 turns on, power is supplied to the oscillation circuit 4 and the booster circuit 5, and the rectifier circuit 6, a high DC voltage is generated, and the capacitor C2 is charged to a predetermined voltage level determined by the voltage detection circuit 7 via the charging resistor R1.

When ultraviolet rays from the flame are continuously incident on the discharge tube 8, the above operation is repeated, and a pulse voltage is generated at both ends of the discharge load resistor R2 each time the discharge tube 8 discharges. It is input to the signal processing circuit 9 of the stage. Since the signal processing circuit 9 does not generate a fire signal by ultraviolet rays that are sporadically generated other than a fire, the signal processing circuit 9 determines that a fire occurs only when a predetermined number of discharge pulses are detected within a predetermined time, and the switching circuit 2 is activated. When the power is turned on, a warning current is passed between the signal line for power supply and the line connected between terminals L and C, and a fire signal is sent to the receiver to notify the occurrence of fire.

As described above, in the embodiment of FIG. 1, in the steady monitoring state after the charging of the capacitor C2 is completed after the power is turned on, the circuit in which the current consumption of the oscillator circuit 4 and the booster circuit 5 is large. Since the power supply to the parts is stopped,
The current consumption can be suppressed to a very low value. FIG. 2 is a block diagram of an embodiment showing a second embodiment of the present invention.

In the second embodiment of FIG. 2, the oscillator circuit 4
And the booster circuit 5 are provided with transistors Q1 and Q2 as power supply switch circuits, respectively, and the voltage detection circuit 7 controls ON / OFF in common. According to the second embodiment, the cost of the transistor used in the power supply switch circuit can be reduced as compared with the first embodiment shown in FIG.

That is, in the embodiment of FIG. 1, since the power supply for both the oscillation circuit 4 and the booster circuit 5 is performed by one transistor Q1, a transistor with a large power loss corresponding to the current consumption of both must be used. I have to. On the other hand, in the embodiment of FIG. 2, since the transistors Q1 and Q2 are individually provided for each of the oscillator circuit 4 and the booster circuit 5, if transistors with small power loss corresponding to respective current consumption are used. It will be done.

For example, for the power loss of the transistors Q1 and Q2 of FIG. 2, the transistor Q of FIG.
When the power loss of 1 is doubled, the cost is about 10 times, and therefore, as shown in FIG. 2, the transistors Q1 and Q2 are individually provided to the oscillation circuit 4 and the booster circuit 5, respectively.
It is more cost effective to provide the above. 1 and 2
In the above embodiment, PNP type transistors are used as the transistors Q1 and Q2 of the power supply switch circuit, but NPN type transistors may be used. When the NPN type transistor is used, the NPN type transistor is provided between the oscillator circuit 4, the booster circuit 5 and the earth line side of the circuit. Further, the power supply switch circuit is not limited to the transistor, and a latching relay controlled by the output of the voltage detection circuit 7 or the like may be used.

FIG. 3 is a block diagram of an embodiment showing a third embodiment of the present invention. In the third embodiment, the first of FIG.
In addition to the embodiment, the power supply to the signal processing circuit 9 is controlled to be turned on and off. In FIG. 3, a transistor Q3 as a second power switch circuit is connected to the power supply line from the constant voltage circuit 3 for the signal processing circuit 9, and the transistor Q3 is turned on / off by a one-shot multivibrator circuit 10 functioning as a timer circuit. I'm trying to control.

One-shot multivibrator circuit 10
Is triggered by the voltage pulse obtained in the discharge load resistor R2 by the discharge operation of the discharge tube 8, and turns on the transistor Q3 for a predetermined time for counting the number of discharge pulses which the signal processing circuit 9 determines to be a fire. The discharge pulse initially obtained by the discharge of the discharge tube 8 is the one-shot multivibrator circuit 10.
Therefore, the signal processing circuit 9 counts the second and subsequent discharge pulses of the discharge pulse train which is continuously output, and a predetermined period until the transistor Q3 is turned off and the power supply is cut off. When the number of pulses is counted, the switching circuit 2 is turned on and a fire detection signal is sent to the receiver.

As the one-shot multivibrator circuit 10, a retriggerable one-shot multivibrator circuit that can be retriggered each time a discharge pulse is obtained may be used. The transistors Q1 and Q3 are PN
Although a P-type transistor is shown, an NPN-type transistor may be used.

[0031]

As described above, according to the present invention, in a flame detection device using a discharge tube that discharges by the incidence of ultraviolet rays emitted from a flame, a circuit for generating and maintaining a dischargeable voltage of the discharge tube is provided. By supplying power for the minimum required time, a significant reduction in current consumption can be realized.

Further, the signal processing circuit that counts the discharge pulse of the discharge tube is not supplied with power in the steady monitoring state, but is supplied to the signal processing circuit only for a predetermined time after the discharge tube is discharged by the incidence of ultraviolet rays from the flame. The current consumption can be further reduced by supplying. Due to such a large reduction in current consumption, it is possible to reduce the backup battery capacity used at the time of a power failure provided in the receiver and to increase the number of flame detection devices that can be connected to one line from the receiver, which is economical. It is possible to realize various equipment configurations.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment showing a first embodiment of the present invention.

FIG. 2 is a block diagram of an embodiment showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram of an embodiment showing a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional device.

[Explanation of Codes] 1: Depolarization circuit 2: Switching circuit 3: Constant voltage circuit 4: Oscillation circuit 5: Booster circuit 6: Rectifier circuit 7: Voltage detection circuit 8: Discharge tube 9: Signal processing circuit 10: One shot Multivibrator circuit (timer circuit) C1: Smoothing capacitor C2: Discharge capacitor R1: Charging resistance R2: Discharge load resistance Q1, Q2: Transistor (power switch circuit or first
Power switch circuit) Q3: Transistor (second power switch circuit)

Claims (2)

[Claims] 1. A discharge tube for detecting and discharging ultraviolet rays or the like emitted from a flame, a booster circuit for generating a high voltage applied to the discharge tube, an oscillator circuit for driving the booster circuit, and the booster circuit. A capacitor that is charged by the output voltage of the discharge tube to store the discharge charge of the discharge tube, and a signal processing circuit that counts the pulses obtained for each discharge of the discharge tube and determines a fire when a pulse count value of a predetermined value or more is obtained; In a flame detection device equipped with, a power switch circuit for turning on and off power supply to a circuit portion having a large current consumption including the oscillation circuit and a booster circuit, and monitoring the applied voltage of the discharge tube, the detected voltage is A voltage detection circuit that turns off the power switch circuit to stop the power supply when the voltage is higher than a predetermined level, and turns on the power switch circuit to supply the power when the voltage is lower than the predetermined level. Flame detection apparatus according to claim. 2. A discharge tube that detects and discharges ultraviolet rays or the like emitted from a flame, a booster circuit that generates a high voltage applied to the discharge tube, an oscillator circuit that drives the booster circuit, and the booster circuit. A capacitor that is charged by the output voltage of the discharge tube to store the discharge charge of the discharge tube, and a signal processing circuit that counts the pulses obtained for each discharge of the discharge tube and determines a fire when a pulse count value of a predetermined value or more is obtained; In a flame detection device including: a first power switch circuit for turning on / off a power supply to a circuit portion having a large current consumption including the oscillation circuit and a booster circuit; and monitoring and detecting a voltage applied to the discharge tube. When the voltage is above a predetermined level, the power switch means is turned off to stop power supply, and when the voltage is below a predetermined level, the first power switch circuit is turned on to supply power, and a voltage detection circuit, A second power switch circuit for turning on and off power supply to the logic circuit; and a second power switch circuit for a predetermined time to turn on the signal processing circuit when a discharge pulse is obtained by the discharge of the discharge tube. A flame detection device comprising: a timer circuit for supplying.