JPS6349824Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dual-sensitivity type smoke sensor capable of detecting two different types of smoke density.

Conventionally, in photoelectric smoke detectors, a light-emitting element periodically emits light, and changes in the emitted light from the light-emitting element are received by a light-receiving element due to smoke flowing into the smoke detector, and fire detection is performed based on the light receiving output of the light-receiving element. is being carried out.
Such smoke detectors must detect the occurrence of an emergency fire as soon as possible, and the detection sensitivity of the smoke detector is set high to detect the occurrence of a fire at an early stage. In addition, when a fire occurs, fire prevention equipment such as fire doors, smoke prevention equipment, and fire extinguishing equipment must be activated to ensure that the fire is extinguished. If the fire control device is activated by the detection output of a smoke detector with a high detection sensitivity as described above, the detection sensitivity of the smoke detector is high, so it will detect smoke from cigarettes, etc. and send out a non-fire alarm. There was a risk that the fire disposal equipment would be activated even though there was no fire. Furthermore, in the event of a fire, priority is given to saving lives and fire disposal equipment is activated once evacuation is complete. It is required to be able to detect and not cause false alarms.

Therefore, a smoke detector with high detection sensitivity that detects the occurrence of a fire at an early stage and a smoke detector with low detection sensitivity for fire control are installed in the same warning area, and smoke detectors with high detection sensitivity are installed in the same warning area. The detection output notifies the first alarm and sounds the district bell, etc. to issue a fire alarm, and at the same time suppresses the detection sensitivity and uses the detection output of the non-operating smoke detector to activate the fire disposal equipment and dispose of the fire. However, there was a problem in that the equipment configuration became complicated and the equipment cost increased.

For this reason, an ionization type smoke detector has been proposed as a smoke detector having two sensitivities. This sensor simultaneously outputs the smoke detection signal from the ionization type smoke detector to a first receiver that receives the smoke detection signal and a second receiver that has an accumulation circuit. Receive the signal early and send out a fire signal. Sensitivity is switched at the same time as this fire signal is sent. After this sensitivity switching, the second receiver was activated to activate the smoke prevention device and the like.

However, since the smoke detection signal from the detection unit is output to the first and second reception units at the same time, there were cases where both were received due to noise, and a fire signal and an activation signal for smoke prevention equipment etc. were output. .

The present invention was developed in view of the above problems, and uses a single smoke detector to detect the occurrence of a fire at an early stage and issue a fire alarm, as well as to continuously monitor the progress of the fire. In a dual-sensitivity type smoke detector that can send out a detection signal when a predetermined fire level is reached and activate a smoke prevention device or the like to take care of the fire, the first detection sensitivity is the first smoke concentration detection. the second detection sensitivity until the signal is sent out.
The purpose is to prevent the smoke concentration detection signal from being output.

To achieve this purpose, the present invention includes a smoke detection section that outputs a smoke detection signal when smoke generated by a fire is detected, and a first detection sensitivity set in the smoke detection section during normal times. Sensitivity switching means is provided for setting a second detection sensitivity different from the first detection sensitivity in the smoke detection section when a smoke detection signal is obtained according to the sensitivity, and the detection operation of the detection section based on the second detection sensitivity In a dual-sensitivity type smoke detector that outputs a second smoke concentration detection signal, a blocking circuit is provided to prevent transmission of the second smoke concentration detection signal for a predetermined period of time from the time of transmission of the first smoke concentration detection signal. This is how it was done.

Embodiments of the present invention will be described below based on the drawings.

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

First, to explain the configuration, P1, P2, and P3 are terminals, and a thyristor S is connected between the terminals P1 and P3.
1. A first switching circuit consisting of resistors R1 and R2 is connected, and high detection sensitivity (first
The thyristor S1 is switched in response to the detection output (detection sensitivity), and sends out an alarm signal (first smoke concentration detection signal). Further, a second transistor consisting of a thyristor S1 and resistors R3 and R4 is connected between terminals P6 and P7.
A switching circuit is connected, and the thyristor S2 is switched by a detection output with a detection sensitivity (second detection sensitivity) lower than the first detection sensitivity, and sends out a detection signal (second smoke concentration detection signal). Diodes D2 and D are connected from terminals P1 and P2, respectively.
3 to the constant voltage power supply 1, and supplies a power supply voltage adjusted to a predetermined voltage. 2 is an oscillation circuit, and an output terminal P that outputs a predetermined pulse width T1
4, P5, and the output terminal P4 outputs drive pulses with a pulse width T1 at predetermined intervals T2. In addition, the output terminal P5 also outputs a clock pulse similar to that of the output terminal P4, and the output timing of the clock pulse is determined by the output timing of the light emitting element PH1 and the light receiving element.
PH2 and the comparator circuit 4 are output with a delay of an appropriate time determined by the circuit characteristics of the comparator circuit 4, for example 1/2T1, with respect to the drive pulse of the output terminal P4.

A resistor R5 and a light emitting element PH1 are connected in series between signal lines led out from terminals P4 and P3.
A light receiving element PH2 and a resistor R10 are connected in series between the power lines drawn out from the constant voltage power supply 1, and a capacitor C1 is connected from the connection point of the light receiving element PH2 and the resistor 10.
The input terminal is connected to the resistor R11 and the positive terminal of the comparator circuit 4 via the resistor R11. Light receiving element PH2 is light emitting element PH1
It is arranged so that the emitted light does not enter directly.

10 is a sensitivity switching circuit for switching detection sensitivity, which includes resistors R6, R7, R8, R9, and a transistor.
The movable terminal of the variable resistor RV is connected to the negative terminal of the comparator circuit 4, and under normal conditions, the divided voltage determined by the resistors R9, R8 and the variable resistor RV is connected to the negative terminal of the comparator circuit 4. It is given as a reference voltage V _L and set to the first detection sensitivity. When the alarm circuit formed by thyristor S1 operates,
The base of the transistor TR is pulled to the L level through the diode D1 connected to the terminal P1 and the inverters 8 and 3, turning on the transistor TR, shorting the resistor R9, thereby increasing the reference voltage applied to the negative terminal of the comparator circuit 4. is converted from V _L to V _H determined by the resistor R8 and the voltage divider of the variable resistor RV, and the detection sensitivity is switched to the second detection sensitivity. 5 and 6 are D-type F/F circuits that operate in synchronization with the clock pulse output from the terminal P2 of the oscillation circuit 2, and the output of the comparator circuit 4 is given to the input terminal DT1 of the F/F circuit 5. , F/ from output terminal Q1 via resistor R13.
It is connected to the input terminal DT2 of the F circuit 6. Resistor R13, capacitor C3, diode D5, and inverter 7 form a delay circuit, and the alarm operation of thyristor S1 causes diode D1, inverter 8,
When the cathode side of the diode D5 is pulled to L level through the capacitor C3, the detection signal output from the terminal Q1 of the F/F circuit 5 is charged to the capacitor C3 through the resistor R13, the capacitor C3, the diode D5, and the inverter 7. At this time, the potential of the input terminal DT2 of the F/F circuit 6 is the capacitor C3,
It is set so that the threshold level _VSH is reached after a predetermined time T3 determined by the time constant of the resistor R13 has elapsed. The resistor R14 and the diode D6 are a discharge circuit that discharges the charge stored in the capacitor C3, and the time constant is set to be small to rapidly discharge the charge in a short time T4. Here, the pulse width T1 and pulse period T of the drive pulse output from the oscillation circuit 2 are
2. Time constants T3 and T4 are set as follows.

T2>T4 T3>T2>T1 The output terminal Q2 of the F/F circuit 6 is connected to the thyristor S.
It is connected to the gate side of the first switching circuit equipped with R12 to send out the first smoke concentration detection signal, and is also connected as an input to the reset terminal RE of the F/F circuit 5 via a resistor R12. Further, the F/F circuit 6 is reset by the output from the terminal Q1 of the F/F circuit 5, and the time constant T5 determined by the capacitor C2 and the resistor R12 is set to a time shorter than the pulse period T2 of the clock pulse. After the smoke concentration detection signal is sent out, the reset of the F/F circuit 6 is delayed to provide an operating time for the detection relay (not shown). A capacitor C4 and a resistor R15 are connected in parallel to the power line drawn out from the constant voltage power supply 1, and the connection point of the capacitor C4 and resistor R15 is connected to the input gate of NOR9 via a terminal P6, and a resistor R16 and a diode D1 are connected. It is connected to the terminal P1 via the terminal P1. When terminal P1 is pulled to L level by sending out the first smoke concentration detection signal,
Charging of the capacitor C4 is started with a time constant determined by the capacitor C4 and the resistor R16. At this time, the time T6 until the potential of the terminal P6 reaches the threshold voltage V _SH of the NOR circuit 9 is
By setting the time constant T5 to be longer than the time constant T5 for applying the reset signal to the thyristor 2, the thyristor 2 is prevented from operating immediately after the first smoke concentration detection signal is sent. When the terminal P6 reaches the L level as the charging of the capacitor C4 progresses, the NOR circuit 9 operates the thyristor S2 with an inverted OR output with the output signal from the inverted output terminal Q2 of the F/F circuit 6, and the second Sends a smoke concentration detection signal.

Next, the operation will be explained with reference to the waveform diagram in FIG.

First, to explain the detection operation at the initial stage of a fire, Fig. 2A is a waveform diagram of the drive pulse output from the terminal P4 of the oscillation circuit 2, and the light emitting element PH1 intermittently emits light in synchronization with the drive pulse. let The emitted light from the light emitting element PH1 is scattered by the inflow of smoke, and the light receiving output from the light receiving element PH2 shown in FIG. The negative input terminal of the comparator circuit 4 has the first detection sensitivity,
That is, the reference voltage V _L is set, and when the received light output exceeds the reference voltage V _L , the output waveform shown in FIG.
Output to DT1. The F/F circuit 5 operates at the rising edge of the clock pulse shown in FIG.
At the timing shown in FIG. E, the output terminal Q1 of the F/F circuit 5 is inverted to H level. This output signal is applied to the input terminal DT of the F/F circuit 6 as shown in FIG. 2F.
As shown in FIG. 2G, the F/F circuit 6 is activated at the next rising edge of the clock pulse, and an H level is output to the output terminal Q2. With this output signal, the F/F circuit 5 is reset after a predetermined time T5 has elapsed, and the thyristor S1 is activated to send out the first smoke concentration detection signal. F/F after time T5 has elapsed as shown in Fig. 2 E, F, G.
When the circuit 5 is reset, the terminal Q of the F/F circuit 5
The F/F circuit 5 is reset by the output from 1.
Further, when the thyristor S1 operates as shown in FIG. 2H, the terminal P6 is pulled to the L level via the diode D1 and the resistor R16. At this time, the potential of the terminal P6 is set to reach the threshold voltage _VSH after a time constant T6 determined by the capacitor C4 and the resistor R16 has elapsed, as shown in FIG. 2J, and the time constant T6 is set by the F/F circuit. Since the time constant T5 is set longer than the time constant T5 which provides the reset timing of 6, the inverted OR output of the NOR circuit 9 cannot be obtained, and the operation of the thyristor S2 immediately after sending out the first smoke concentration detection signal is prevented.

Next, a detection signal when a predetermined fire level is reached as the fire situation progresses will be explained. Thyristor S1
Due to the alarm operation, terminals P1 and P3 are short-circuited,
The base of the transistor TR is pulled to L level via the diode D1 and the inverters 8 and 3, and the transistor TR is turned on in synchronization with the drive pulse from the oscillation circuit 2. When the transistor TR is turned on, the resistor R9 is short-circuited, and the reference voltage applied to the negative input terminal of the comparator circuit 4 is changed from V _L to V _H , thereby switching the detection sensitivity to the second detection sensitivity. That is, after sending out the first smoke concentration detection signal, the detection sensitivity is suppressed and the progress of the fire is further monitored continuously. In response to the inflow of a large amount of smoke, the emitted light from the light emitting element PH1 is scattered, and when the scattered light enters the light receiving element PH2,
The light receiving output from the light receiving element PH2 shown in FIG. 2C is input to the positive terminal of the comparator circuit 4. When the received light output exceeds the reference voltage _VH , the output waveform shown in FIG. 2D is applied from the output terminal of the comparison circuit 4 to the input terminal DT1 of the F/F circuit 5. The F/F circuit 5 is shown in Fig. 2B.
It operates at the rising edge of the clock pulse shown in FIG. 2, and outputs an H level to the output terminal Q1 of the F/F circuit 5 at the timing shown in FIG. 2E. On the other hand, when the thyristor S1 is turned on, the diode D1 and the inverters 8 and 7
The cathode side of the diode D5 is pulled to the L level through the output terminal Q of the F/F circuit 5.
The H level detection output from 1 is charged to the capacitor C3 of the storage circuit. As shown in FIG. 2F, when the potential of the input terminal DT2 of the F/F circuit 6 exceeds the threshold voltage V _SH after time T3 has elapsed, the F/F circuit 6 operates at the rising edge of the next clock pulse and the output terminal Q2 goes low. Flip to level. Also,
Since the terminal P6 of the NOR circuit 9 is at the L level, an H level is output from the output terminal of the NOR circuit 9, and as shown in FIG. Send.

In the embodiment shown in FIG. 1, the light emitting element PH
The so-called scattered light method is arranged so that the light emitted from the light receiving element PH2 does not directly enter the light receiving element PH2, and the scattered light due to the inflow of smoke is made to enter the light receiving element PH2, and smoke detection is performed based on the light receiving output of the light receiving element PH2. We have explained the two-sensitivity type smoke detector, but the light emitting element
The emitted light from PH1 is made incident on the light receiving element PH2,
It can also be applied to a so-called dimming-type dual-sensitivity type smoke detector that detects smoke based on the light receiving output of the light receiving element PH2 due to the attenuation of the emitted light due to the inflow of smoke.

Next, the effect will be explained.

According to the present invention, the smoke detection signal of the second detection sensitivity is blocked until the first detection sensitivity outputs the smoke detection signal, so that a dual-sensitivity smoke detector can eliminate malfunctions due to noise. In normal times, the first detection sensitivity, that is, the detection sensitivity, is set high to detect the occurrence of a fire at an early stage and send out a fire alarm (first smoke concentration detection signal), and a different detection sensitivity (second detection sensitivity) is set. detection sensitivity), and when a predetermined fire level is reached as the fire situation progresses, the detection signals are accumulated and a second smoke concentration detection signal is sent after a predetermined delay. The detector sounds the district bell etc. based on the first smoke concentration detection signal to issue a fire alarm at the initial stage of the fire, and also sends out the second smoke concentration detection signal after a predetermined period of time after sending out the first smoke concentration detection signal. Based on the smoke concentration detection signal, smoke prevention equipment and the like can be activated to efficiently handle fires, and interlocking control of disaster prevention equipment can be performed without erroneous operation due to non-fire alarms.

Further, a second smoke detection concentration signal is transmitted by transmitting the first smoke detection concentration signal.
Since a blocking circuit is provided to prevent the smoke concentration detection signal from being sent out, it is possible to reliably send out the smoke concentration detection signal according to the detection sensitivity without causing malfunction.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a waveform diagram showing the waveforms of each part in FIG. 1. 1: Constant voltage power supply, 2: Oscillation circuit, 3, 7, 8:
Inverter, 4: Comparison circuit, 5, 6: F/F circuit, 9: NOR circuit, 10: Sensitivity switching circuit, P1,
P2, P4, P5, P6, P7: terminal, S1, S
2: Thyristor, R1,...R16: Resistor, D1,
...D6: Diode, RV: Variable resistor, PH
1: Light emitting element, PH2: Light receiving element, C1 to C3:
Capacitor, TR: Transistor.

Claims (1)

[Claim for Utility Model Registration] A detection unit that outputs a smoke detection signal when smoke generated by a fire is detected, and a first detection sensitivity set in the detection unit during normal times, and When the detection signal is obtained, the first
In a dual-sensitivity smoke detector, the second smoke concentration detection signal is transmitted only for a predetermined period of time from the time when the first smoke concentration detection signal is sent. A dual-sensitivity type smoke detector characterized by being provided with a blocking circuit that prevents the emission of smoke.