JPH021661Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is an analog fire detector that inputs analog fire detection signals such as temperature and smoke density associated with a fire detected by an analog fire detector into a receiver to determine the presence or absence of a fire. This invention relates to a test device used for testing the operation of sensors in fire alarm equipment.

In conventional fire alarm equipment, when a fire detector installed in a restricted area detects a fire, a pair of power signal lines drawn out from the receiver are shorted to low impedance, and an alarm current is sent to the receiver. This alarm current is detected and a fire alarm is issued.

However, in such conventional fire alarm equipment using so-called on/off type fire detectors, fires are determined only by the presence or absence of alarm current from the fire detector, so the amount of information from the detector is limited. As a result, false alarms were generated due to malfunction of the detector, and it was difficult to determine the circumstances leading up to the fire and the extent of the fire after it occurred.

Therefore, in recent years, as a fire detector,
A so-called analog fire alarm system has been proposed in which an analog fire detection signal corresponding to temperature, smoke concentration, etc. is directly transmitted to a receiver, and the presence or absence of a fire is determined from the received analog fire detection signal at the receiver.

By the way, even with such analog fire alarm equipment, as with conventional fire alarm equipment, operation tests must be conducted periodically to check whether the analog fire detector is operating normally. Test equipment was needed.

The present invention was developed in view of the above, and is a fire alarm system that is built into a receiver to easily and reliably test whether an analog fire detector is working properly. The purpose is to provide

To achieve this objective, the present invention includes an output section for outputting a test signal to the fire detector in the receiver, and a memory for storing the steady output level of the fire detector when outputting the test signal from the output section. a calculation means for calculating a level difference between the steady output level stored in the storage means and the test output level from the fire detector according to the test signal from the output section;
and a discrimination circuit that activates an alarm circuit when it is determined that the data of the calculation means is out of a predetermined range, and when the fire detector receives a test signal from the receiver, Means for transmitting a test output to the receiver is provided, so that it is possible to easily test and determine whether or not the fire detector having an analog function is operating normally.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a circuit block diagram showing an embodiment of an analog fire alarm system equipped with the testing device of the present invention.

First, to explain the configuration of the receiver side, numeral 1 is a microcomputer that executes fire discrimination and sensor testing under program control, and an A/D converter 2 is connected to the microcomputer 1.
The A/D converter 2 converts an analog detection signal from an analog fire detector into a digital signal and inputs the digital signal to the microcomputer 1. Further, an alarm sensitivity setter 3 and a test sensitivity setter 24 are connected to the microcomputer 1, and the alarm sensitivity setter 3 is used to calculate the alarm reference value for fire discrimination in the microcomputer 1. The set value is used, and the set value from the test sensitivity setter 24 is used for test determination when performing an operation test.

Further, the microcomputer 1 is connected via an interface 4 to a display section and an operation circuit section for displaying fire alarms, operation test displays, etc.

That is, the fire indicator lights 5a to 5 serve as display units.
n, operating lights 6a to 6n, and a buzzer 7 are provided, and a display control circuit 8 is provided for the fire lights 5a to 5n.
The buzzer 7 is connected to the interface 4 via a re-sounding circuit 9.

The output of the interface 4 and the output of the reset switch 10 are connected to the re-sounding circuit 9 via an OR gate 11, and the reset switch 10 is operated to turn off the buzzer 7 in the event of a fire or when an abnormality is detected in the sensor by an operation test. In addition to stopping the sound, the buzzer 7 can be made to sound again by the output from the microcomputer 1 when an alarm from another line is detected after the sound of the buzzer 7 is stopped when a fire is determined.

Also, test switch 1 is installed on interface 4.
2 is supplied via the RS-FF 13, and the operation of the fire detector is tested by operating the test switch 12.

On the other hand, a power switch 16 is connected to the lines L1 to Ln to which the analog fire detectors 15a to 15n are connected.
Subsequently, a power supply circuit 17 is provided, and a test circuit 18
A current detection circuit 20 is connected to each line L1 to Ln via
a to 20n are provided, and current detection circuits 20a to 2
0n converts the line current corresponding to the analog detection signals of the analog fire detectors 15a to 15n into voltage and inputs it to the A/D converter 2.
The analog detection data is converted into digital data and supplied to the microcomputer 1.

Here, the test circuit 18 selects the sensor lines L1 to Ln to be tested based on a line selection signal given via the interface 4 when a test command is given to the microcomputer 1 by operating the test switch 12. One of the functions is to send out a test voltage different from the power supply voltage in the steady monitoring state by the power supply circuit 17 as a test signal. Therefore, the analog fire detectors 15a to 15n detect the test voltage sent out from the test circuit 18, perform a test operation, and detect the emission obtained by the test operation, as will be explained in detail later. Report current to line L1
~Equipped with a test operation function that flows to Ln.

The embodiment shown in FIG. 1 is an analog fire detector 15.
This example is a test device for a two-wire fire detector in which a to 15n are connected between each of the lines L1 to Ln and the common line Lc. Regarding the 3-wire analog fire detector shown in Publication No. 57-33508, which has a test line added in addition to the power signal line that applies a test voltage to the source of the FET installed in the fire detector and performs an operation test. It can be applied as is.

Next, referring to the flowchart in Figure 2,
An operation test for the analog fire alarm system shown in the figure will be explained.

During the operation test, when a test switch 12 provided on the receiver is turned on, the RS-FF 13 is set and an operation test is commanded to the microcomputer 1 via the interface 4. Upon receiving this test command, the microcomputer 1 first tests block a as shown in the flowchart of FIG.
Set the line number N to be tested as N=N+1 (however,
The initial value of N is 0), and the first line L1 corresponding to N=1 is selected as the line to be tested in block b. Next, in block c, the current detected by the current detection circuit 20a in a non-test state, that is, in a steady state, is sampled from the conversion data from the A/D converter 2. In order to prevent detection errors due to

Next, in block d, the microcomputer 1 gives a control command to the test circuit 18 to send a test voltage as a test signal to the line L1 selected in block b via the interface 4, and sends the test voltage to the line L1. Send. By sending out this test voltage, the analog fire detector 15a connected to the line L1 enters a test operation state, and a test current corresponding to the test operation is passed through the line L1.

Therefore, as shown in block e, the test current detected by the current detection circuit 20a is digitally converted by the A/D converter 2 and sampled by the microcomputer 1 to obtain test data T. It is desirable that the sampling of the test data T in this block e is also detected as the average of three pulses of the test current, similar to the detection of the steady current S in the block c.

Next, in block f, the difference (T-S) between the test current T detected in block e and the steady-state current S detected in block c falls within a predetermined range corresponding to the test sensitivity set by the test sensitivity setting device 24. Analog fire detector 15
If a is normal, the change in alarm current corresponding to the allowable value in the predetermined range a corresponding to the test sensitivity, that is, (T-S), is obtained, so the operation test of line L1 is completed and the determination is made. Proceeding to block g, it is determined whether the selected line N matches the number of lines n,
At this time, since N=1, the process returns to block a again and moves on to the operation test of the second line where N=2.

On the other hand, when the difference (T-S) between the test current T and the steady-state current S is out of the predetermined range a corresponding to the test sensitivity in the determination block f, it is determined that there is an abnormality in the operation of the analog fire detector 15a. The process then proceeds to block h, where the microcomputer 1 outputs a control signal to the display control circuit 8 via the interface, and detects an abnormality in the sensor by driving the fire light 5a provided corresponding to the analog fire detector 15a to blink. At the same time, the re-sounding circuit 9 sounds the buzzer 7 to issue a test alarm.

Thereafter, similar sensing operation tests are repeated in the order of lines L2 to Ln, and when the operation test of the final line with line number N=n is completed, the series of operation tests according to the flowchart of FIG. 2 is completed.

On the other hand, fire detection in the analog fire alarm system shown in Figure 1 starts with detecting the line current of each line at regular intervals as the average of three pulses shown in block c of the flowchart in Figure 2 in the steady monitoring state. Then, a value obtained by adding a predetermined value corresponding to the alarm sensitivity set by the alarm sensitivity setting device 3 to this steady current value S is created as the alarm reference value, and this alarm reference value and the line current are combined in the next sampling. When the detected current exceeds the alarm standard value in any sampling period, it is determined that there is a fire, and the fire light 5a of the corresponding line is activated.
~5n lights up and the buzzer 7 starts to sound. In addition, the alarm standard values for fire detection are:
When the detected current has been sampled a predetermined number of times, a refresh is performed to perform the calculation again based on the detected current at that time. Also,
Operating light 6 during steady monitoring status and operation tests
A to 6n are always lit to indicate that fire monitoring is being performed normally.

Furthermore, although the above embodiment is based on the case where analog fire detectors connected to all lines are automatically tested when the test switch 12 is operated, line numbers can be specified using a keyboard or the like. By operating the test switch 12, it is also possible to designate a specific line and conduct an operation test.

In the example, the control is performed by a microcomputer, but for example, the output from the analog sensor during steady state can be configured with a first hold circuit using a capacitor, and the output during testing can be configured using a capacitor. Of course, it may also be a hardware configuration in which the hold outputs of the first and second hold circuits are input to a differential amplifier, the level difference is taken out, and it is determined whether or not it is normal.

Figure 3 shows the specific circuit configuration of the analog fire detector shown in the embodiment of Figure 1.The feature of this analog fire detector is that dust accumulates on the ionization type smoke detector after long-term use. If the sensor output changes due to the adhesion of dirt such as dirt, the test output is also changed depending on the dirt.

First, to explain the configuration, an analog fire detector 1 is connected to a pair of power signal lines from the receiver.
A diode bridge using diodes D1 to D4 is provided following the terminals a and b of No. 5, and this diode bridge is designed so that the power signal line from the receiver can be connected in a non-polar manner to the terminals a and b. There is. Following this diode bridge, a capacitor C1 and a constant voltage circuit 32 are provided to supply each circuit section of the analog fire detector 2 with a constant power supply voltage, for example 13 volts.

Reference numeral 35 denotes an ionization type smoke detection section, and the ionization type smoke detection section 35 is composed of an external electrode 36, an intermediate electrode 37, and an internal electrode 38 equipped with a radiation source 39. An outer chamber is formed into which smoke from the outside flows in, and an inner chamber is formed between the intermediate electrode 37 and the inner electrode 38 into which smoke from the outside does not flow.

The intermediate electrode 37 of this ionization type smoke detection section 35 is
Field effect transistor (hereinafter referred to as FET) 40
This FET 40 is an insulated gate type with the Vg-Id characteristics shown in Figure 4.
FETs, ie MOS-FETs, are used. FET
The source S of 40 is input connected to an amplifier 33, and the output of the amplifier 33 is connected to the base of a transistor 34, and the transistor 34 performs ionization detection between the power supply and signal line from the receiver via a diode D5 and a resistor R5. A detection current corresponding to the detection output of the smoke section 35 is made to flow as an analog fire detection signal.

Next, in order to detect the test voltage sent out from the test equipment as a circuit for testing the operation of the analog fire detector 2, a Zener diode ZD is installed.
If the test voltage from the test equipment is, for example, 30 volts, the zener voltage of the zener diode ZD is set to 27 volts. The cathode side of this Zener diode ZD is connected to the base of the transistor 44 via a resistor R6, and when the Zener diode ZD is turned on by the test voltage, the transistor 44, which has a base bias circuit consisting of a resistor R4 and a capacitor C2, is turned on. ing. The collector of the transistor 44 is connected to the constant voltage circuit 32 via resistors R3, R2 and FET42,
Ionization type smoke detection section 3 from the connection point of resistors R2 and R3
The power supply voltage is supplied to 5.

Here, as FET42, Vgs-
A junction FET with Id characteristics is used, and FET4
0 source S is feedback connected to the gate G of FET42, and further a resistor R1 is connected as a source load of FET40.
is connected between each source S of FET40 and 42, and the ionization type smoke detection section 3 is connected by FET40 and 42.
A compensating circuit is formed for dirt such as dust attached to 5.

Next, the compensation function of the test output against the adhesion of dirt in the analog fire detector 15 shown in FIG. 3 will be explained.

First, the value of the source-drain impedance Zf of the FET 42 and the resistance R2 is determined to be in the relationship Zch≫Zf Zch≫R2 with respect to the chamber impedance Zch of the ionization type smoke detector 35, so no test operation is performed. In the steady monitoring state, the power supply voltage E determined by the constant voltage circuit 32 is supplied to the ionization type smoke detector 35 as is.

Here, the relationship between the ion current and the interelectrode voltage, that is, the chamber voltage, in the ionization type smoke detection section 35 is as shown in the graph of FIG. 6, and the characteristics of the ion current with respect to the external chamber voltage V1 and the internal chamber voltage V2 are as follows. The relationship is as shown by the solid line in FIG. 7, and an ion current flows with the operating point being point A, which is the intersection of the ion current characteristics of the inner chamber and the ion current characteristics of the outer chamber.
Therefore, when smoke from a fire flows into the external chamber, the ionic current in the internal chamber does not change, and the ionic current in the external chamber decreases due to the inflow of smoke, resulting in the characteristic shown by the broken line, and the operating point moves from point A to point B and the external chamber voltage V
1 increases, the internal chamber voltage V2 relatively decreases, and due to the inflow of smoke, the chamber voltage becomes ΔV, that is, the voltage of the intermediate electrode 37 changes.

The voltage change ΔV due to the inflow of smoke at the intermediate electrode 37 increases the source-gate voltage Vgs in the FET 40 in FIG. 3, and as is clear from the characteristic graph in FIG. This will cause an analog detection output to be generated in response to the inflow of smoke.

The relative relationship between the external chamber voltage V1 and the internal chamber voltage V2 in the ionization type smoke detection section 35 in this steady state and when smoke is flowing in is shown in FIGS. 8A and 8B.

Next, when a test voltage is received from the test device connected to the receiver side, the Zener diode ZD becomes conductive, turning on the transistor 44, and by connecting the resistor R3 in parallel with the ionization type smoke detector 35, A divided voltage determined by the combined impedance of the resistor R3, the resistor R2, and the FET 42 is supplied as a chamber voltage, and the chamber voltage of the ionization type smoke detector 35 is lowered. In other words, when the transistor 44 is turned on, a chamber voltage of V1+V2=E×R3/(Zf+R2+R3)...(1) is applied,
The chamber voltage changes to a lower chamber voltage by the voltage drop ΔE across FET42 and resistor R2.

The chamber voltage during this test is shown in Figure 8C.
From the characteristics of the external chamber voltage and internal chamber voltage shown in FIG. A test with a constant sensitivity between the upper and lower limits of abnormality determination in the test equipment connected to the receiver side by increasing the voltage Vgs between the source and gate of FET 40. It is designed to produce an output.

Next, a compensation operation when dirt such as dust adheres to the ionization type smoke detection section 35 will be explained.

If there is dirt on the ionization type smoke detection part 35 during the test after long-term use, that is, if there is dirt such as dust on the external chamber that receives smoke from the outside, Air molecules ionized by the alpha rays emitted from the radiation source 39 adhere to the particles, and as a result, the ion current decreases. In response to this decrease in the ion current, the source-gate voltage Vgs of the FET 40 increases in the same way as when smoke flows in, and as is clear from the characteristic graph in FIG. 4, the drain current Id of the FET 40 increases.
1 increases. The drain current Id of this FET40
1 flows through the resistor R1, so the resistor R1
As a result, the gate-source voltage Vgs of the FET 42 increases. In response to this increase in the gate-source voltage Vgs of FET42, FET42
has the characteristics shown in Figure 5, so its drain current increases as the gate-source voltage Vgs increases.
Id2 increases, and as a result, as shown in the graph of FIG. 9, impedance Zf between the source and drain of FET 42 decreases as drain current Id2 of FET 42 decreases.

As described above, if an operation test is performed on the analog fire detector 15 in a state where the impedance Zf of the FET 42 is reduced due to the adhesion of dirt to the ionization type smoke detector 35, the external chamber voltage due to the transistor 44 being turned on by the test voltage will be The detection output increases compared to when there is no dirt attached, and the detection output during the test increases by the same amount that the sensor output in the steady state increases due to the dirt attached, so even if there is dirt attached to the sensor, the sensitivity is always constant. The test output can be obtained as follows.

Although the above example was an example of an operation test for a 2-wire analog fire detector, this test also applies to a 3-wire analog fire detector in which the power line and signal line are drawn out separately from the receiver. can be similarly applied.

As explained above, according to the present invention, a fire detector that detects changes in physical phenomena due to fire in an analog manner is connected to the signal line drawn out from the receiver, and analog fire detection from this fire detector is performed. Targeted at fire alarm equipment that warns of fire by distinguishing detection signals by a receiver, the receiver includes an output section that outputs a test signal to a fire detector, and an output section that outputs the test signal from the output section. a storage means for storing a steady output level of a fire detector; and a calculation for calculating a level difference between the steady output level stored in the storage means and a test output level from the fire detector based on a test signal from the output section. and a discrimination circuit that activates an alarm circuit when it is determined that the data of the calculation means is out of a predetermined range, the fire detector receiving a test signal from the receiver. By providing a means to send a test output to the receiver, it is possible to remotely test the operation of the analog fire detector and know the operating status of the detector, thereby increasing the reliability of the fire detector. You can improve your sexuality. Furthermore, since judgments are made based on the difference between the steady output level of a fire detector with an analog function and the output level during testing, accurate testing is possible without being affected by noise such as dirt. becomes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of an analog fire alarm system including the test device of the present invention, Fig. 2 is a flowchart showing the test operation of the present invention according to the embodiment of Fig. 1, and Fig. 3 is a A circuit diagram showing a specific example of an ionization type smoke detector whose operation is tested using the test device of the present invention. Figures 4 and 5 show the Vgs-Id characteristics of FET40 and 42 used in the sensing circuit of Figure 3. Figure 6 is a graph showing the relationship between the chamber voltage and ion current in the sensor in Figure 4, and Figure 7 shows the relationship between the ion current in the sensor in Figure 4 and the external chamber voltage and internal chamber voltage. Graphs shown for each, Figure 8 is an explanatory diagram showing the interrelationship of chamber voltages in the detector in Figure 4 during steady state, fire detection and testing, Figure 9 is the sensor circuit in Figure 4. FET in
FIG. 4 is a graph showing impedance changes with respect to drain current of No. 42. 1: Microcomputer, 2: A/D converter, 3: Alarm sensitivity setting device, 4: Power supply circuit, 5a~
5n: Fire light, 6a to 6n: Operating light, 7: Buzzer, 8: Display control circuit, 9: Re-sounding circuit, 10:
Reset switch, 11: OR gate, 12: Test switch, 13: RS-FF, 15a-15
n: analog fire detector, 16: power switch,
17: Power supply circuit, 18: Test circuit, 20a-20
n: current detection circuit, 24: test sensitivity setter, 3
2: Constant voltage circuit, 33: Amplifier, 34, 44: Transistor, 35: Ionization smoke detector, 36: External electrode, 37: Intermediate electrode, 38: Internal electrode, 3
9: Radiation source, 40, 42: FET.

Claims (1)

[Scope of claim for utility model registration] A fire detector that detects changes in physical phenomena due to fire in an analog manner is connected to a signal line drawn out from a receiver, and the analog fire detection signal from the fire detection is sent to the receiver. In a fire alarm system that discriminates and warns of fire, the receiver includes an output section that outputs a test signal to the fire detector, and a steady output of the fire detector when outputting the test signal from the output section. storage means for storing levels; calculation means for calculating a level difference between the steady output level stored in the storage means and the test output level from the fire detector according to the test signal from the output section; and the calculation means a discrimination circuit that activates an alarm circuit when it is determined that the data of the fire detector is outside a predetermined range; A fire alarm system characterized by having a means for sending out a test output.