JPH0319032Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a malfunction prevention device for a fire alarm system.

[Background Art] Fig. 1 shows a schematic configuration diagram of a malfunction prevention device for this type of fire alarm system, in which reception relays Ry ₁ are provided for each area corresponding to each line of receiver A.
A DC voltage is applied from the receiver A to the common line lc between each sensor connection line _l1 ... and the common line lc. Then, when any of the smoke detectors 1a, heat detectors 1b, etc. connected in parallel between each sensor connection line _l1 ... and the common line lc is turned on, the sensor connection line _l1 ... and the common line lc are connected. This reduced voltage is input to the voltage detection input terminal of the line voltage detection circuit section 3 through the diode OR consisting of diodes D1, and the line voltage detection circuit section 3 detects this change in line voltage. Detects and generates a detection output. This detection output turns on the switching circuit section 4. This ON operation drives the high-sensitivity relay 5, and the normally closed contact b of the relay contact _r0 of the high-sensitivity relay 5 is turned off, and the common line
Release lc. As a result of this opening, the energizing path for the excitation current of the receiving relay Ry ₁ in the receiver A is formed by the receiving relay Ry ₁ , the sensor connection line l ₁ , the smoke detector 1a, and the common line lc. It will be blocked. In other words, it is faster (e.g., 10 msec) than the time required for receiving relay Ry ₁ to operate (e.g.,
1msec) When the high-sensitivity relay 5 operates, the receiving relay Ry ₁ does not operate and the receiver A does not issue an alarm. Now, simultaneously with the ON operation of the switching circuit section 4, the first timer circuit section 7 starts a time-limiting operation.
Here, during the time limit operation period of the first timer circuit section 7,
In other words, while the switching circuit section 4 is on, the starting end of the common line lc is open due to the normally closed contact b of the relay contact _r0 being turned off, so the smoke is being operated by the power supply from the receiver A. The sensor 1a ceases to operate and returns to normal operation, and since the line voltage is restored, the line voltage detection circuit 3 no longer generates a detection output, and the switching circuit 4 is turned off. As a result of this turning off, the high sensitivity relay 5 returns to its original state and turns on the normally closed contact b of its relay contact _r0 . Due to this turning on, the DC voltage from receiver A is applied again between both lines l ₁ and lc. Power will also be supplied to the smoke detector 1a, but whether the smoke detector 1a is a photoelectric type or an ion type,
Since it takes several seconds to about 10 seconds from the time the power is turned on until the smoke detection operation starts, the smoke detector 1a turns on again with a slight delay after the DC voltage is applied. . This ON operation causes the line voltage to drop, and the line voltage detection circuit section 3 again generates a detection output, turning on the switching circuit section 4 and driving the high sensitivity relay 5. In this way, the high-sensitivity relay 5 is driven every time the smoke detector 1a operates, thereby preventing the receiving relay Ry ₁ of the receiver A from operating and self-holding. The operating time of this high-sensitivity relay 5 is the first
It is defined by the time limit operation time of the timer circuit section 7. In other words, when the first timer circuit section 7 times up, it sends a time-up output to the second timer circuit section 8, and causes the second timer circuit section 8 to perform a time-limited operation from the time-up of the first timer circuit section 7. During this period, a signal is generated to turn off the switching circuit section 4. Therefore, when the smoke detector 1a operates during the time limit operation period of the second timer circuit section 8, the reception relay Ry ₁ of the receiver A is connected to the sensor connection line _l1 and the smoke detector 1 is connected to the reception relay Ry 1 of the receiver A.
An excitation current flows through a, the common line lc, and the normally closed contact b of relay contact r ₀ , operating the receiving relay Ry ₁ , forming its self-holding circuit, and transmitting an alarm from the receiver A. It turns out. By the way, if the smoke detector 1a does not operate during the time limit operation period (for example, 30 to 40 seconds) of the second timer circuit section 8, the reception relay Ry ₁ of the receiver A will not operate. This indicates that the sensor operation during the time limit operation period of the first timer circuit section 7 was a temporary malfunction, and false alarms due to malfunction could be prevented. If the sensor operates after the time limit operation of the second timer circuit section 8 ends, the line voltage detection circuit section 3 and the switching circuit section 4
By the action of the high-sensitivity relay 5, the line opening operation is performed in the same manner as described above. In this way, even if the sensor is operating during the time limit operation period of the first timer circuit section 7, this operation is ignored, and the second
The corresponding receiving relay of receiver A is activated only when the corresponding sensor operates during the time limit operation period of the timer circuit section 8.
By operating Ry ₁ ..., it is possible to prevent malfunctions due to temporary sensor operation.

By the way, in such a system as shown in FIG. 1, the time limit operation period of the first timer circuit section 7 is common to each sensor connection line l ₁ . Ta. In addition, 6 in FIG. 1 is a constant voltage circuit section, and this constant voltage circuit section 6 is connected to the existing power output terminal L provided for supplying DC power from the receiver A to the sub-receiver etc., and the common connection terminal C. The DC output between the two is stabilized to a DC output of a predetermined voltage, and the stabilized DC output is supplied to each of the above circuits as a power source. Further, 9 is a constant voltage circuit section 6 and a high sensitivity relay 5.
A malfunction prevention circuit section includes a switching circuit section 4, a line voltage detection circuit section 3, and first and second timer circuit sections 7 and 8. Also L ₁ ~
Ln is the sensor connection line connection terminal, r is the reception relay Ry ₁
This is a self-holding relay contact.

[Purpose of the invention] This invention was created in view of the above-mentioned problems, and its purpose is to prevent the receiving relay of the receiver from operating due to a temporary malfunction of the sensor or receiver. To provide a malfunction prevention device for a fire alarm system, which can increase the reliability of the system by adjusting the time limit operation time of a first timer circuit section of a malfunction prevention circuit section corresponding to each line. .

[Disclosure of the invention] The invention will be explained below using an embodiment shown in FIG. The circuits in Figure 2 with the same numbers and symbols as those in Figure 1 operate in the same way, including the line voltage detection circuit section 3, the switching circuit section 4, and the circuit section 5. a high-sensitivity relay 6, a constant voltage circuit section 6, a first timer circuit section 7, a second timer circuit section 8, and a time limit adjustment circuit section 10 which is the main component of the present invention. The malfunction prevention circuit section 9 is constructed from the above. First timer circuit section 7
The resistor R ₁ and the capacitor C ₁ constitute a basic time constant circuit for time-limited operation, and a time-limit adjustment circuit section 10 is connected in parallel to the resistor R ₁ .
The time limit adjustment circuit section 10 is constructed by connecting a plurality of series circuits in parallel, each consisting of a PNP transistor Tr ₁ ... provided corresponding to each sensor connection line l ₁ ... and a variable resistor VR ₁ ... for time limit adjustment. Then connect the parallel circuit to the above resistor.
The base of each transistor Tr _{1 .} . . is connected to the corresponding sensor connection line l _{1 .} . . via a diode d ₁ .

However, assuming that the current state is normal, the voltage between each sensor connection line _l1 ... and the common line lc is the voltage output from receiver A via the corresponding receiving relay _Ry1 ... Since no base current flows through the base of the transistor Q ₁ of the line voltage detection circuit section 3 via the diode D ₁ , the transistor Q ₁ is in an off state. Here, the diodes _D1 ... have their anodes commonly connected to the base of the transistor _Q1 , and their cathodes individually connected to the corresponding sensor connection lines _l1 .... Now, in the second timer circuit section 8, since the input of inverter IN ₁ is "L", its "H"
The inverter IN ₂ whose input terminal is connected to the output of the inverter IN 2 generates an "L" output, and this output is connected to the input terminal of the NOR gate NOR ₁ of the first timer circuit section 7 . In addition, since the input of inverter _IN3 is at the "H" level, the output is set to "L", and the NOR gate
Connected to the other input of NOR ₁ . The NOR gate NOR ₁ of the first timer circuit section 7 has another input terminal connected to another NOR gate NOR ₂ . Since the NOR gate NOR ₂ has an "H" input when the transistor Q ₂ of the switching circuit section 4 is in the off state,
The output is “L”, so the above-mentioned NOR gate
NOR ₁ sets the output to "H" and prevents charging of the capacitor C ₁ of the time constant circuit connected to the output terminal.

Now, for example, when the smoke detector 1a connected to the sensor connection line _l1 detects smoke and turns on, a connection between the sensor connection line _l1 and the common line lc is created via the impedance of the smoke detector 1a. is shortened, and the voltage between both lines l ₁ and lc drops. Due to this drop, a base current immediately flows to the base of the transistor Q ₁ of the line voltage detection circuit section 3 via the diode D ₁ , turning on the transistor Q ₁ . As a result of this turning on, a charging current flows through the transistor _Q1 to the capacitor _C2 , and the capacitor _C2 is charged. Therefore, the voltage across the capacitor C ₂ increases, the base current flows through the transistor Q ₂ of the switching circuit section 4, turning it on, and the high-sensitivity relay 5 is connected between the output terminals of the constant voltage circuit section 6 via the transistor Q _2. is connected to drive the high-sensitivity relay 5. The high-sensitivity relay 5 turns off the normally closed contact b of the relay contact r ₀ and opens the common line lc. This release causes the reception relay in receiver A to
The path of the excitation current of the receiving relay Ry ₁ formed by Ry ₁ , the sensor connection line l ₁ , the sensor, and the common line lc is cut off. That is, receiving relay Ry ₁
If the high-sensitivity relay 5 operates earlier (for example, 1 msec) than the time required for the operation (for example, 10 msec), the receiving relay Ry ₁ does not operate and the receiver A does not issue an alarm.

Now, when the voltage between the sensor connection line _l1 and the common line lc decreases, a base current flows through the diode _d1 to the base of the transistor _Tr1 of the time limit adjustment circuit section 10, turning on the transistor Tr1 and turning on the corresponding _one . Variable resistor for time-limited adjustment via transistor Tr ₁
VR ₁ is connected in parallel to the resistor R ₁ of the first timer circuit section 7. Here, the switching circuit section 4
When transistor Q ₂ turns on, the NOR gate
The output of NOR ₂ becomes "H", and the output of NOR gate NOR ₁ of the first timer circuit section 7 becomes "L". Therefore _, the charging current of capacitor C 1 flows through the parallel circuit of resistor R ₁ and variable resistor VR ₁ , capacitor C ₁ , and NOR gate NOR ₁ , and the capacitor
Start charging _C1 . At the same time, the output of the inverter IN ₃ of the second timer circuit section 8 changes from "L" to "H".
Even if the output of the NOR gate NOR ₂ returns to "L", charging of the capacitor C ₁ of the timer circuit section 7 will continue until the charging voltage becomes "H". On the other hand, when the starting end of the common line lc is opened by turning off the normally closed contact b of the relay contact _r0 , the smoke detector 1a, which was being operated by the power supply from the receiver A, no longer operates. It will disappear and then come back. In addition, since the voltage between the sensor connection line _l1 and the common line connection terminal C is also restored, the transistor _Q1 of the line voltage detection circuit section ₃ is activated by discharging the charge in the capacitor C2. It turns off with a slight delay (for example, 0.5 seconds) from the time of recovery, turning off the transistor _Q2 of the switching circuit section 4. Due to this turning off, the high sensitivity relay Ry ₁ returns to its original state and turns on the normally closed contact b of its relay contact r ₀ . By turning this on, the starting end of the common line lc is connected to the common line connection terminal C of receiver A, and both lines
A DC voltage from receiver A will be applied between l ₁ and lc. Power is also supplied to the smoke detector 1a, but whether the smoke detector 1a is a photoelectric type or an ion type, it takes several seconds to 10 seconds from the time the power is turned on until it shifts to smoke detection operation. Since it takes about seconds, the smoke detector 1a turns on again with a slight delay from the application of the DC voltage. This on operation causes the voltage between the sensor connection line _l1 and the common line lc to drop. This voltage drop is detected by the line voltage detection circuit section 3, and the switching circuit section 4 is turned on again, and the high sensitivity relay 5 is turned on.
to drive. In this way, the smoke detector 1a
The high-sensitivity relay 5 is driven every time the receiver A operates, thereby preventing the receiver A's receiving relay Ry ₁ from operating and self-holding. The operable period of this high-sensitivity relay 5 is defined by the time limit operation time of the first timer circuit section 7, and as the capacitor _C1 described above is charged, the charging voltage of this capacitor _C1 becomes "H". Inverter IN ₃ changes from “H” to “L” at the time of aging.
to be reversed. Due to this reversal, charging of the capacitor _C3 starts, and at the same time as this starts, the output of the inverter _IN2 becomes "H". Simultaneously with this "H" transistor _Q3 turns on, and this turns on the transistor Q3 of the switching circuit section 4.
Ground the base of Q ₂ . Therefore, even if the line voltage detection circuit section 3 performs a detection operation thereafter, the switching circuit section 3 will not be turned on. Therefore, when the smoke detector 1a operates during the ON period of the transistor _Q2 , the reception relay _Ry1 of the receiver A has the sensor connection line _l1 , the smoke detector 1a, and the common line.
An excitation current flows through lc and the normally closed contact b of relay contact r ₀ , the receiving relay Ry ₁ operates, and its self-holding circuit is formed, and the receiver A issues an alarm. Now, the second timer circuit section 8
When the charging of the capacitor _C3 progresses and the charging voltage becomes "H", that is, when the time is up, the output of the inverter _IN2 is reversed from "H" to "L", the transistor _Q3 is turned off, and the switching circuit section 4 is turned off. Return to operational state. By the way, during the time limit operation period of the second timer circuit section 8 mentioned above,
If the smoke detector 1a does not operate, the receiving relay Ry ₁ of the receiver A does not operate, and this means that the operation of the smoke detector 1a during the time limit operation period of the first timer circuit section 7 is temporary. This indicates that there was a sexual malfunction, and this means that false alarms due to malfunction can be prevented. Further, if there is no sensing operation of the smoke detector 1a during the time limit operation period of the second timer circuit section 8, and if the smoke sensor 1a operates after the time limit operation ends, the line voltage detection circuit section 3 and the switching circuit section 4 Then, the line opening operation by the high sensitivity relay 5 is performed in the same manner as described above. In addition, Q ₄ in the figure is the second
When the output of the inverter IN ₃ of the timer circuit section 8 is "H", that is, during the time limit operation of the first timer circuit section ₇ , this transistor is turned _on. A current is applied to the circuit to cause it to emit light, indicating that the first timer circuit section 7 is in a time-limiting operation. Further, LED _G is a green light emitting diode that causes a current to flow through the transistor Q ₃ when the transistor Q ₃ is turned on, and emits light to indicate that the second timer circuit section 8 is in a time-limited operation, and LED _Y is a green light emitting diode. relay contacts
It is, for example, a yellow light emitting diode that emits light when r ₀ is switched from normally closed contact b to normally open contact a to indicate that the high sensitivity relay 5 is in operation.

Here, FIG. 3a shows the sensing operation and recovery operation of the smoke detector 1a connected to the above-mentioned sensor connection line _l1 , and FIG. 3b shows the time limit of the first timer circuit section 7 at that time. The cancel period due to the operation is shown, and _FIG . Here, the time limit operation time of the first timer circuit section 7 is determined by a resistor _R1 ,
The time limit is set by the resistance value of the parallel circuit with the variable resistor VR ₁ of the time adjustment circuit section 10, and by adjusting the variable resistor VR ₁ , the time limit can be set to a time suitable for the sensor connection line _l1 . By the way, sensor connection line l ₁
If the smoke detector 1a connected to a sensor connection line other than _L2 , for example _, operates as shown in FIG. ₂ also turns on, so the variable resistor R ₁ is connected to the resistor R 1 of the first timer circuit section 7 _.
In addition, the variable resistor R ₂ is also connected in parallel, so that the time constant becomes smaller, and as shown in FIG. The time when the timer circuit unit 8 starts expiring, that is, the reception relays Ry ₁ and Ry ₂ of the receiver A
The time when receiver A becomes operational becomes earlier as shown in FIG. 3f, and early operation of receiver A is obtained. In other words, the more the smoke detectors 1a connected to the lines operate, the shorter the cancellation period becomes, and the earlier the occurrence of a fire can be detected. Furthermore, when the heat sensor 1b connected to the line is activated, the heat sensor 1b starts to recover quickly, so the heat sensor 1b operates as shown in FIG. , Therefore, the capacitor _C1 of the first timer circuit section 7 is charged faster, and as shown in FIG.
The cancel period becomes shorter as shown in FIG. 3, and the time point at which the second timer circuit section 8 starts expiring, that is, the time point at which the receiving relay Ry ₁ of the receiver A becomes operable becomes earlier as shown in FIG. 3i. In other words, it is possible to provide a difference in the cancel period between the smoke detector 1a and the heat sensor 1b. In the above embodiment, the sensor operation is detected by detecting a change in the line voltage, but the sensor operation may be detected by detecting the line current. Further, the time limits of the first and second timer circuit sections 7 and 8 are based on 10 to 20 seconds and 30 to 40 seconds.

[Effects of the invention] The invention provides a line condition detection means that generates an output when the voltage applied between the common line and each sensor connection line or the line current changes to a predetermined level, and a detection output of the line condition detection means. a switching circuit unit that drives a switching means whose operation time is faster than that of the receiving relay; and a switching circuit unit that starts a time-limited operation from the start of operation of the switching circuit unit and sets the switching circuit unit in an on-operable state until the time-up period elapses. a first timer circuit section that starts a time-limited operation from the time-up of the first timer circuit section and sets the switching circuit section in an OFF state until a preset time elapses; The malfunction prevention circuit section is configured to open at least the starting end portion of either the sensor connection line or the common line by the switching means when the switching means is driven by the switching circuit section. During the time-limiting operation of the timer circuit section, the sensing operation of the sensor or transmitter can be canceled, thereby preventing temporary malfunctions.Moreover, due to the time-limiting operation of the second timer circuit section, the sensing operation of the sensor or transmitter can be canceled. Since the operating period of the relay is set, if there is no alarm by the end of this period, it will return to the original state and prevent false alarms by the line status detection means, switching circuit section, and first timer circuit section, and the system will be improved. In addition, it is provided corresponding to each sensor connection line, and operates when the voltage between the sensor connection line and the common line changes to the above-mentioned predetermined level. Since the timer circuit section is equipped with a time limit adjustment means that connects a variable resistor for time limit adjustment in parallel to the time constant resistor, the cancel period can be set arbitrarily for each line by adjusting the resistance value of the variable resistor. It is easy to configure, and one malfunction prevention circuit can support multiple lines.The configuration is simple, so manufacturing costs are low.Furthermore, when the sensors of multiple lines operate, the variable resistors of the lines can be connected in parallel. Since it is connected to the time constant resistor of the first timer circuit section, the cancel period can be shortened, and there is an advantage that a fire can be detected early if there is a high probability that a fire will occur.

[Brief explanation of the drawing]

Fig. 1 is a basic schematic circuit diagram of a malfunction prevention device for a fire alarm system, Fig. 2 is a circuit diagram of an embodiment of the present invention, Fig. 3 is an explanatory diagram of the same operation, and 1a is a smoke detector. , 1b is a heat sensor, 2 is a transmitter, 3 is a line voltage detection circuit section, 4 is a switching circuit section, 5
1 is a high-sensitivity relay, 7 is a first timer circuit section, 8 is a second timer circuit section, 9 is a malfunction prevention circuit section, 1
0 is a time limit adjustment circuit, R ₁ is a resistor, VR ₁ is a variable resistor, l ₁ is a sensor connection line, lc is a common line, and Ry ₁ is a receiving relay.

Claims (1)

[Scope of utility model registration request] DC voltage is applied between the common line and each sensor connection line through the receiving relay in the receiver, and a transmitter, heat sensor, or smoke detector is connected between each sensor connection line and the common line. In a fire system in which a heat detector or a smoke detector is connected in parallel and an exciting current is sent to the receiving relay through the sensor when the sensor is turned on, the applied voltage between the common line and each sensor connection line, a line state detection means that generates an output when the line current changes to a predetermined level; a switching circuit section that uses the detection output of the line state detection means to drive a switching means whose operation time is faster than that of the receiving relay; and the switching circuit. a first timer circuit section that starts a time-limited operation from the start of the operation of the first timer circuit section and sets the pre-start switching circuit section in an on-operable state until time-up; and a time-limited operation that starts from the time-up of the first timer circuit section; and a second timer circuit section which sets the switching circuit section in an OFF state until a preset time has elapsed. A malfunction prevention circuit section is provided in which at least one of the starting end portions is open, and is provided corresponding to each sensor connection line, so that the voltage between the sensor connection line and the common line is set to the above-mentioned predetermined value. Malfunction prevention of a fire alarm system characterized by comprising a time limit adjustment means that operates when the level changes and connects a variable resistor for time limit adjustment in parallel to a time constant resistor of the first timer circuit section. Device.