JPH02287696A - Fire sensor - Google Patents

Abstract

PURPOSE:To improve the reliability of detection data by switching to a larger time constant than an integral time constant at the time of sample-and-hold and eliminating a noise component contained in a continuous output, when the continuous output is discriminated form a classification signal of a head. CONSTITUTION:As for an installation of a head 12-1 provided with a photoelec tric smoke detecting part brought to intermittent driving, based on a classifica tion signal from a classification voltage generating circuit 16-1, a head output is brought to sample-and-hold 38 by synchronizing with intermittent driving of the head by a base part 10, and thereafter, brought to A/D conversion 26 and sent out to a receiver. On the other hand, as for an installation of a head part 12-2 provided with an ionization smoke detecting part for generating a continuous output, based on a classification signal from a classification voltage generating circuit 16-2, an integration circuit consisting of a capacitor C0 of the sample-and-hold circuit 38, and a resistance R0 connected by turn-on of an analog switch 40 is formed, and by eliminating a noise component conforming to an integral time constant of the capacitor C0 and the resistance R0, a detecting signal from which the noise component is eliminated is supplied to the A/D converter 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fire detector in which a head having a base portion equipped with different types of detection portions, such as a photoelectric type or an ionization type, can be used in common.

[Prior Art] Conventionally, as this type of fire detector, the one shown in FIG. 7, for example, is known.

In FIG. 7, 10 is a base portion fixed to a ceiling surface or the like, and 12 is a head portion detachably provided to the base portion 10. In FIG.

A detection unit 14 is built into the head unit 12, and the detection unit 14 includes a photoelectric smoke detection unit that is driven intermittently, an ionization smoke detection unit that generates continuous output, and a temperature sensor that outputs analog fire temperature. A thermal detection section, etc., is provided.

Further, the head 12 is provided with a type voltage generation circuit 16.
The detection unit 14 generates a type voltage indicating whether it is a photoelectric type, an ionization type, or a thermal type, and supplies it to the base unit 10.

On the other hand, the base section 10 is provided with a constant voltage circuit 18, 28, an interface circuit 20, an address switch 22, a transmission control circuit 24, and an AD converter 26, and receives a call from a receiver via the interface circuit 20, for example. When the transmission control circuit 24 determines that the address corresponds to the own address by the address switch 22, the detection signal from the detection unit 14 of the head 12, which is input to the AD converter 26 at that time, is converted into digital data and sent to the receiver. I come to do it.

Furthermore, the transmission control circuit 24 determines the type of the detection unit 14 based on the type voltage from the type voltage generation circuit 16 provided in the head 12, and since the photoelectric type is driven intermittently, the intermittent drive cycle of the detection unit 14 Synchronized AD converter 2
The output signal is sampled and converted into digital data by operation 6. On the other hand, since the ionization type and thermal type are continuous outputs, they do not require any synchronization.
The D converter 26 is operated to convert the data into digital data.

[Problem to be solved by the invention] However, in such conventional fire detectors, ionization type and thermal type detectors that generate continuous output, the output containing noise is sampled as is. Since the data is converted into digital data, there is a risk that abnormal data due to noise may be transmitted to the receiver, which poses a problem of lowering the reliability of fire judgments.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a fire detector in which appropriate signal processing corresponding to the detection type of the head can be performed by switching control on the base side. shall be.

[Means for Solving the Problems] First, the present invention consists of a head part and a base part, and is connected to a transmission line led out from a receiver to detect changes in physical phenomena caused by a fire and collect fire detection data. Targets fire detectors that emit .

Regarding such a fire detector, the present invention first includes a detection section in the head section that detects changes in physical phenomena due to fire and outputs the output intermittently or continuously; A type signal generating section is provided which generates a type signal indicating the type of output.

On the other hand, the base section includes a sample hold means for sample-holding the output from the detection section in synchronization with the intermittent output when the intermittent output is determined from the head type signal; When the determination is made, a filter is provided that fixes the sample hold means in a sample operation state and switches an integration time constant during the sample hold to a larger time constant to remove noise components included in the continuous output from the detection section. a noise filter forming means for forming a noise filter; and a transmission means for transmitting a signal held by the sample hold means or a signal obtained via the noise filter forming means to a receiver as fire detection data. It is.

[Function] In the fire detector of the present invention having such a configuration, when a head equipped with an intermittently driven photoelectric smoke detector is attached, the base side controls the head based on the type signal. The head output is sampled and held in synchronization with intermittent drive, and then AD converted or current converted and sent to the receiver, while the head is equipped with an ionization type or thermal type detection section that generates continuous output. , the sample and hold circuit fixes the sample operation state in which the signal from the head passes through as is based on the type signal from the head, and also switches to a larger time constant than the integration time constant during sample and hold. A noise filter can be configured to remove noise components included in the continuous output, and after noise removal, the signal is converted into an AD or current and sent to a receiver.

Therefore, the base can be used in common for different head types, and the reliability of fire detection data can be improved by forming a processing circuit suitable for the head type in the base.

In addition, instead of installing different processing circuits in the base and switching between them, the circuit has been changed so that the sample-hold circuit provided for intermittent output forms a noise filter for continuous output. Since circuit processing can be commonly used, the circuit configuration and scale can be simplified.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a base part, which is installed on the ceiling surface, etc., and has a terminal, to which a power signal line (transmission line) drawn out from the receiver is connected to C.

The base portion 10 is provided with constant voltage circuits 18, 28, 30, an interface circuit 20, an address switch 22, a transmission control circuit 24, and an AD converter 26.

The constant voltage circuit 18 supplies a power supply voltage v to a circuit section within the base section 10.
1, for example, vl; 5 volts. The constant voltage circuit 28 supplies a power supply voltage v2 to the head section 12-2 equipped with an ionization type smoke detection section, which will be explained later.For example, V2=10 volts, and the type voltage from the transmission control circuit 24 When it is determined that the ionization type smoke detection section is present, the control is performed so that a constant voltage output V2 of 10 volts is output.

Furthermore, the constant voltage circuit 30 includes a head unit 1 equipped with a photoelectric smoke detection unit that employs an intermittent drive method that will be explained later.
In contrast to 2-1, when driving the light emission, the power supply voltage ■3, for example, V3=
It supplies 18 volts, and is controlled to intermittently output a constant voltage v3 in synchronization with a predetermined light emission drive timing when the transmission control circuit 24 determines the type voltage indicating the photoelectric smoke detector. .

An analog switch 32, a capacitor CO1, and a transistor 36 for discharging and resetting the capacitor Co are provided on the input side of the AD converter 26 which A/D converts the head detection output and supplies digital data to the transmission control circuit 24. A sample and hold circuit 38 is provided.

That is, the sample and hold circuit 38 is connected to the transmission control circuit 24.
By turning on the analog switch 32 using the control output, the detection output from the head side is connected to the capacitor C.

By charging the capacitor C, sampling is performed, and by turning off the analog switch 32 after this sampling, the capacitor C is
Performs a hold operation to keep the voltage charged to o constant,
After the hold voltage of the capacitor Co is converted into digital data by the AD converter 26 and taken into the transmission control circuit 24, the transistor 36 is turned on to reset the capacitor CO by discharging.

An analog switch 40 and a resistor RO are connected in parallel to the analog switch 32 provided in such a sample hold circuit 38.
series circuits are connected in parallel.

The series circuit of the analog switch 40 and the resistor Ro forms a noise filter using the capacitor CO provided in the sample and hold circuit 38. That is, with the analog switch 32 and transistor 36 of the sample-and-hold circuit 38 fixed off.

By turning on the analog switch 40, the resistance Ro
and capacitor CO are formed, and resistor R
The noise component included in the output signal from the head side is removed by an integral time constant determined by the resistance value of O and the capacitance of capacitor CO, and the signal is input to the AD converter 26.

Next, the head section 12-1 side will be explained.

In the embodiment shown in FIG. 1, a head section 12-1 having a photoelectric smoke detection section is connected to the base section 10.

That is, the head portion 12-1 includes a light emitting element 44 and a light receiving element 4.
Since the photoelectric smoke detector usually uses a scattered light method, the light receiving element 46 is provided at a position where it does not directly receive the light from the light emitting element 44 for the smoke detection space in the head.
is installed.

The light emitting element 44 is driven to emit light by a drive circuit including a transistor 42, resistors R1 to R4, a Zener diode ZD, and a diode D2.

That is, when no light is emitted, a power supply voltage of V2 = 10 volts is supplied from the constant voltage circuit 28 provided in the base portion 10, and the Zener diode Z
The Zener voltage of D is greater than 2, so the transistor 48 is off.

On the other hand, during light emission driving, a power supply voltage of V3 = 18 volts is supplied from the constant voltage circuit 30 provided on the base portion 10 side, and the Zener diode Z
Since the zener voltage of D is low, the zener diode ZD
conducts, the transistor 42 is turned on, and the light emitting element 44 is driven to emit light.

Note that the capacitor C1 is provided as a power backup to prevent the power supply voltage from the diode D2 onward from decreasing even if a sufficient light emitting current flows when the light emitting element 44 is driven to emit light by turning on the transistor 42.

The light receiving element 46 is input connected to the amplifier 48, and the light emitting element 4
4 is driven to emit light, a received light output of scattered light corresponding to the concentration of smoke flowing in and out of the smoke detection space is generated, and is supplied to the AD converter 26 via the sample hold circuit 38 of the base section 10.

Further, the head portion 12-1 includes a type voltage generation circuit 16-1.
Since a photoelectric smoke detection section is provided in the head section 12-1, a type voltage representing the photoelectric smoke detection section is output to the transmission control circuit 24 of the base section 10.

FIG. 2 is a block diagram of an embodiment of a head section 12-2 equipped with an ionization type smoke detection section mounted on the base section 10 of FIG. 1.

In FIG. 2, a radiation source 50 is included in the head portion 12-2.
An ionization chamber is provided, which includes an internal electrode 52 with a radiation transmitting hole, an intermediate electrode 54 with a radiation transmitting hole, and an external electrode 56 into which smoke can flow from the outside. The element is input to an amplifier 58 having an input stage, and a continuous detection output is generated according to the concentration of incoming smoke.

Further, a type voltage generation circuit 16-
2 is provided to generate a type voltage indicating that the detection section is an ionization type smoke detection section.

LC2 is a capacitor for power backup.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, a sensor call is made to the base section 10 from the receiver via the transmission path in accordance with the transmission format shown in FIG. The calling signal in the format shown in FIG. 3 is sent to the transmission control circuit 2 via the interface circuit 20.
address switch 2 in the transmission control circuit 24.
2 is compared with the calling address, and when the two match, it is determined that the calling address is the calling address.

Here, the transmission signal from the receiver to the base part 10 of the fire detector is carried out in a voltage mode in which the signal voltage vH is superimposed on the power supply voltage VL shown in FIG. Sending of fire detection data to the receiver is performed using two current values It (and I
It is carried out in current mode consisting of L.

When the transmission control circuit 24 determines that there is a call from the receiver, the transmission control circuit 24 outputs a light emission drive control signal to the constant voltage circuit 30, and the constant voltage circuit 30 sets the light emission drive voltage to the head unit 12-1. V3=18 volts is output over a predetermined period.

That is, as shown in FIG. 5(a), the power supply voltage for the head portion 12-1 increases from V2=10 volts to V3=18 volts over a predetermined period T1.

Therefore, the Zener diode ZD of the head portion 12-1 receives V3=18 volts and becomes conductive, and the transistor 42 is turned on, so that the light emitting element 44 is driven to emit light intermittently as shown in FIG. 5(b).

The light from the light emitting element 44 is scattered by the smoke particles that have flowed into the smoke detector and enters the light receiving element 46, and the light receiving output shown in FIG. 5(C) is obtained from the amplifier 48. Incidentally, FIG. 5 shows three states in which the smoke density increases, and accordingly, the received light output shown in FIG. 5(c) increases sequentially.

On the other hand, a sample hold circuit 38 provided in the base section 10
The analog switch 32 is turned on by the transmission control circuit 24 in synchronization with the light emission drive timing of the light emitting element 44, and therefore the light reception output from the amplifier 48 is charged into the capacitor Co through the analog switch 32 which is in the on state. When the sample operation is performed and the light emitting period of T1 ends, the analog switch 32 is turned off and the capacitor C is turned off.
A hold state is entered in which the sample voltage of O is kept constant. The AD converter 26 is operated in the hold state of the sample and hold circuit 38, converts the received light output held in the capacitor Co into digital data, inputs it into the transmission control circuit 24, and outputs the data via the interface circuit 20 as shown in FIG. ) is transmitted to the receiver as bit data in the current mode according to the transmission format shown in FIG.

On the other hand, when the AD conversion by the AD converter 26 is completed, a reset pulse is output from the transmission control circuit 24 to the transistor 36, and by turning on the transistor 36, the discharge of the capacitor Co is reset.

That is, the sample and hold circuit 38 operates as shown in FIG.
), sample and hold of the light reception output from the head section 12-1 and discharge reset are performed.

Next, the operation when the head section 12-2 equipped with the ionization type smoke detection section shown in FIG. 2 is attached to the base section 10 shown in FIG. 1 will be described.

When the head section 12-2 is mounted, the transmission control circuit 24 recognizes that the head section performs continuous output based on the type voltage from the type voltage generation circuit 16-2.

When determining whether a head section that performs such continuous output is attached, the transmission control circuit 24 fixes the analog switch 40 in the always on state, and fixes the analog switch 32 and the transistor 36 of the sample hold circuit 38 in the fixed off state. do.

Therefore, an integrating circuit, ie, a noise filter, is formed by the conde CO of the sample and hold circuit 38 and the resistor RO connected when the analog switch 40 is turned on.

In this state, the amplifier 58 of the head unit 12-2 shown in FIG. 2 provides a detection output containing a noise component as shown in FIG. By removing the noise components accordingly, it is possible to supply the AD converter 26 with a detection output from which the noise components have been removed, as shown in FIG. 6(b).

On the other hand, in response to a call from the receiver with the head unit 12-2 connected, the transmission control circuit 24 determines that it is receiving continuous output from the type voltage of the type voltage generation circuit 16-2. Therefore, the control output for intermittent driving to the constant voltage circuit 30 is not performed, and the AD converter 26 is operated at the timing when the self-call is determined, and the resistor RO
The output voltage from the head section 12-2 obtained through a noise filter consisting of a capacitor CG and a capacitor CG is converted into digital data, and is sent to the interface circuit 20 as current mode bit data according to the transmission format shown in FIG. The signal is then sent to the receiver via the

Incidentally, in the above embodiment, the AD converter 26 provided in the base section 10 converts the output from the head section into digital data and sends it to the receiver.
Current mode transmission may be used in which the head detection output that has passed through a sample hold or noise filter is converted into a current value by a current conversion circuit and output to the receiver without providing a D converter.

Furthermore, in the above embodiment, the head section 10 is configured to transmit fire detection data in response to a call from the receiver using the transmission format shown in FIG. A transmission method that outputs a clock pulse following a reset pulse, counts this clock pulse on the fire detector side, and returns fire detection data when it matches its own setting value can also be applied as is.

Further, in the above embodiments, an ionization type head is used as an example of a head that generates continuous output, but the same applies to a thermal type head.

Further, even if the ionization type is used, it goes without saying that a sample and hold operation is performed if the type performs intermittent operation.

[Effects of the Invention] As explained above, according to the present invention, the base part can be used in common for different head types that produce intermittent output or continuous output, and the circuit processing suitable for the type of head can be implemented in the base. The reliability of detection data can be improved.

In addition, by changing the sample hold circuit installed in the base for intermittent output, it is possible to form a noise filter for continuous output, so the circuit configuration on the base side can be significantly reduced compared to the case where a processing circuit is provided for each head type. It can be simplified.

Furthermore, if a sample hold circuit or a noise filter is provided on the head side, the output impedance to the base will be high and noise will be easily picked up at the fitting connection between the head and the base. Since the sample and hold circuit and the noise filter formed by changing the sample and hold circuit are provided on the base side, the output impedance from the head can be lowered, and the head can be connected to the head without adding a special circuit. Noise pickup at the connection fitting portion of the base can be minimized.

[Brief explanation of the drawing]

Fig. 1 is an embodiment configuration diagram showing an embodiment of the present invention in a state where a head equipped with a photoelectric detection section is attached; Fig. 2 is a diagram showing a head section equipped with an ionization detection section used in the present invention. Embodiment configuration diagram FIG. 3 is an explanatory diagram of the transmission format between the receiver and the sensor; FIG. 4 is an explanatory diagram of the transmission mode between the receiver and the sensor; FIG. 5 is a photoelectric detection unit according to the present invention FIG. 6 is a signal waveform diagram showing the processing operation of the ionization type detection section according to the present invention; FIG. 7 is an explanatory diagram showing the conventional example. 10: Base part 12-1: Head part (photoelectric type) 12-2: Head part (ionization type) 16-1.16-2: Type voltage generation circuit 18.28.3
0: Constant voltage circuit 20: Interface circuit 22 Near address switch 24: Transmission control circuit 26: AD converter 32.40: Analog switch 36.42:) Transistor 38: Sample hold circuit 44: Light emitting element 46: Light receiving element 48.58 : Amplifier 50: Radiation source 52: Internal electrode 54: Intermediate electrode 56: External electrode

Claims (1)

[Claims] 1. A fire detector consisting of a head part and a base part, connected to a transmission line led out from a receiver, detecting changes in physical phenomena caused by fire, and transmitting fire detection data. In the head section, a detection section that detects a change in a physical phenomenon caused by a fire and outputs the output intermittently or continuously; the detection section generates a type signal indicating whether the output is intermittent output or continuous output. a type signal generating section for detecting; and a sample hold means for sample-holding the output from the detecting section in synchronization with the intermittent output when the intermittent output is determined from the type signal; When a continuous output is determined from the type signal, the sample and hold means is fixed to the sampling operation state, and the integration time constant during the sample and hold is switched to a larger time constant to eliminate noise contained in the continuous output from the detection section. noise filter forming means for forming a filter for removing components; transmission means for transmitting the signal held by the sample and hold means or the signal obtained via the noise filter forming means to a receiver as fire detection data; A fire detector characterized by being provided with.