JPH0427598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a fire alarm system, and more particularly to a sensor automatic recovery circuit used during maintenance.

"Prior art" Conventionally, a fire receiver, this fire receiver, or
There is a fire alarm system that consists of a pair of lines extending from a repeater for each warning area, and a plurality of fire detectors connected between the pair of lines. Some fire detectors self-maintain this state by providing low impedance conduction between a pair of wires when activated. The fire receiver detects the line's operating current or the signal from the repeater and issues a fire alarm. Once a fire detector is activated, it will not be restored unless the voltage between the pair of lines is lowered to a predetermined value or lower (lower than the holding current). For this reason, during maintenance and inspection, the fire detector is tested with a detector operation tester, and after confirming operation, the detector automatic recovery circuit can automatically restore the fire detector even if no one is on the fire receiver side. is provided. For example, Japanese Patent Publication No. 55-31960 and Japanese Utility Model Publication No. 50-24084.

``Problems to be Solved by the Invention'' Conventionally, a plurality of lines (pairs of lines) generally extend from a fire receiver or repeater to each warning area. When the sensor automatic recovery circuit is operated during maintenance, a recovery signal (reducing the voltage between a pair of lines to a predetermined value or less) is output to all lines.
This has the disadvantage that the power supply to the fire detector is intermittently cut off because a recovery signal is constantly output even to the line where the fire detector is not operating, which affects the monitoring status.

``Means for Solving Problems'' This invention prevents a recovery signal from being sent to a line where a fire detector is not operating even when the detector is automatically restored, and checks the operation of the fire detector when it is activated. After the line is restored, a recovery signal is output to this line for the first time.

``Function'' Even when the detector is automatically restored, a restoration signal is not output to the line where the fire detector is not operating, so the monitoring status can be maintained normally.

Embodiment An embodiment of the sensor automatic recovery circuit of the present invention will be described based on the drawings. In the drawing, this invention sensor automatic recovery circuit is connected to a normal monitoring power supply E1.
(DC24V) and used during automatic recovery, power supply E1
Power supply E2 (DC15V) set lower than the voltage of
, a power supply circuit consisting of a diode D0 for backflow prevention, a flicker circuit FM that operates during automatic recovery and opens and closes a normally closed contact at a predetermined cycle, and terminals L and C to which a pair of lines (not shown) are connected. and a sensor power supply circuit consisting of resistors R1-3, 14, transistor Q1, diode D1, 2, Zener diode Z1, resistor R4-11, diode D3-6, Zener diode Z2, transistor Q2, 3, and capacitor. A sensor operation detection circuit consisting of C1 and resistors R12, 13, 15 to 1
8, diodes D7-9, transistor Q4,
5. A recovery pulse generation circuit consisting of a capacitor C2, resistors 19, 20, and diodes D10, 1
1, a recovery circuit consisting of a capacitor C3, and a transistor Q6. Terminal F is a fire signal output terminal and is input to a signal processing circuit (not shown).

Note that this sensor automatic recovery circuit is provided in the repeater or receiver, and the number of sensor automatic recovery circuits, excluding the power supply circuit, is provided in accordance with the number of lines.

The operation of the sensor automatic recovery circuit configured as described above will be explained. Since the flicker circuit in the power supply circuit is not operating, the power supply E1 is supplied as the circuit power supply. The transistor Q1 is supplied with base power by the resistor R1 and is in an ON state. Therefore, power is supplied to the terminal L via the resistor R3, the transistor Q1, the diode D2, and the resistor R14. Zener diode Z
1 is for circuit protection and its Zener voltage is set higher than 24V. A fire detector is connected, and a voltage of approximately 24V is applied to a pair of lines extending from terminals L and C. In this state, if the fire detector is activated, a low impedance conduction occurs between the pair of lines. Terminals L and C are almost short-circuited, and capacitor C1 starts charging via resistor R8, diode D4, and resistor R14. When this charging voltage exceeds a predetermined voltage related to the Zener voltage of the Zener diode Z2, the transistor Q2 is turned on. Transistor Q3 is also supplied with base current from a portion of the emitter current of transistor Q2 via resistor R10 and diode D6, turning it on. At this time, the base current of transistor Q2 is supplied from the collector current of transistor Q3. Therefore, the transistors Q2 and Q3 remain in the ON state, and in this state, even if the fire detector is restored, the self-holding state will not be released. Also, terminal F
The voltage changes from a low level to a high level, and is input as a fire alarm signal to a signal processing circuit or an alarm circuit (not shown) to display a fire alarm.

In this state, when an automatic recovery switch (not shown) is operated, the flicker circuit FM operates to open and close the normally closed contacts at a predetermined cycle. The circuit voltage alternates between 24V and 15V. The circuit voltage
At 24V, capacitor C2 is connected to transistor Q2,
It is charged to approximately 24V via diode D7 and resistor R15. At this time, the base current of transistor Q5 does not flow, so it is in an OFF state. Circuit voltage is 24V
When the voltage drops from 15V to 15V, the base voltage of transistor Q5 becomes lower than the emitter voltage due to the charging voltage of capacitor C2, so it is temporarily turned on. Transistor Q4 also has diode D9 and resistor R1.
A base current is supplied through 2 and becomes ON state.
Therefore, the base current of the transistor Q1 is cut off via the diode D1 and the resistor R2 to turn it into an OFF state, and the power supply to the terminal L is cut off, and the terminal L is electrically connected to the terminal C via the transistor Q4, the diode D3, and the resistor R4. . The voltage between the pair of lines is set below a predetermined value (below the holding current) and the fire detector is restored. Even in this state, the transistor Q
The sensor operation detection circuit consisting of 2, 3, etc. is in a self-holding state. When the circuit voltage changes from 15V to 24V, the charging current of capacitor C3 flows through the series circuit between resistor R19, capacitor C3, and the base and emitter of transistor Q6.
Turn on temporarily. At this time, the circuit between the diode D11 and the collector and emitter of the transistor Q6 becomes conductive, cutting off the supply of base current to the transistor Q3 and turning the transistor Q3 off. Therefore, the transistor Q2 is also turned off, and the self-holding state of this sensor operation detection circuit is therefore released.

On a line where the fire detector is not operating, the transistor Q2 of the detector operation detection circuit is in the OFF state, so the capacitor C2 is not charged. Therefore, when the sensor automatically recovers, the circuit voltage will be lower than 24V.
Even if the voltage changes to 15V, transistor Q5 remains OFF and no recovery pulse is output. That is, the sensor power supply voltage between the pair of lines only fluctuates in voltage, and no recovery signal is output.

Generally, fire detectors using semiconductors use a stabilizing circuit, so they can maintain a monitoring state without being affected by slight fluctuations in the power supply voltage.

"Effects of the Invention" As explained above, the sensor automatic recovery circuit of the fire alarm device of the present invention outputs a recovery signal only to the line where the fire detector is operating, and continues to output the recovery signal to the line where the fire detector is not operating. Since power is supplied, it does not affect the monitoring operation of the fire detector and is extremely effective in practice.

[Brief explanation of drawings]

The drawing is a circuit diagram showing one embodiment of the sensor automatic recovery circuit of the fire alarm system of the present invention. R1-20...Resistor, C1-3...Capacitor, D0-11...Diode, Z1,2...Zener diode, Q1-6...Transistor,
FM...Fritzker circuit, E1,2...power supply,
C, L, F...terminals.

Claims (1)

[Claims] 1 Multiple fire detectors connected between a pair of lines, which maintain a short circuit with low impedance during operation and recover when the holding current is below, and a fire receiver, etc. that issues a fire alarm upon receiving the operating signal of the fire detector. In the sensor automatic recovery circuit of a fire alarm system, there is an automatic recovery switch that is operated during maintenance and inspection to set the automatic recovery state, and a power supply that normally supplies monitoring power, and when the automatic recovery switch is operated, the A power supply circuit that alternately outputs a power supply set lower than the voltage of the monitoring power supply and the monitoring power supply at a predetermined period; and a power supply circuit that detects the operating current of the fire detector via the pair of lines; a sensor operation detection circuit that holds and outputs an operation detection signal when detected; and a sensor operation detection circuit that outputs an operation detection signal when the output voltage from the power supply circuit changes from a high voltage to a low voltage. A recovery pulse generation circuit that generates a recovery pulse only when the recovery pulse is outputted, and a recovery pulse generation circuit that normally supplies power from the power supply circuit to the pair of lines via a resistor etc. a detector power supply circuit that reduces the current supplied to the fire detector to a holding current or less;
A sensor automatic recovery circuit for a fire alarm device, comprising a recovery circuit that releases the holding state of the sensor operation detection circuit when the output voltage from the power supply circuit changes from a low voltage to a high voltage.