JPH0370278B2 - - 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 fire alarm system that can identify the type of fire detector activated in a fire receiver.

``Prior Art'' Conventionally, a fire alarm system generally consists of a fire receiver, a pair of lines extending from the receiver to a warning area, and a plurality of fire detectors connected in parallel between the pair of lines. ing. In order to identify which fire detector has activated at the receiver, each detector is equipped with an oscillator with its own frequency, and when activated, this oscillator is interlocked and this signal is superimposed on the line. Distinguish the frequency of this signal,
There is a method to identify activated sensors. (for example,
(Japanese Utility Model Publication No. 54-41669) Also, by connecting a constant voltage element in series to a highly sensitive fire detector and directly connecting a low-sensitivity fire detector, when the detector is activated, the receiver There is a method to identify the type of sensor that was activated based on the difference in voltage between the lines.
(For example, Japanese Utility Model Application Publication No. 57-175288) When linking a fire alarm device with a smoke prevention device or a fire extinguishing device, it is generally done based on the operation of a low-sensitivity fire detector due to reliability issues. . Therefore, when high-sensitivity and low-sensitivity detectors are connected to the same line, it is necessary to identify whether the low-sensitivity fire detector is activated.

``Problems to be Solved by the Invention'' In conventional fire alarm systems, in which each fire detector is provided with an oscillator for identification, the circuit configurations on both the detector and receiver sides become complicated. In addition, in the method of identifying based on the difference in line voltage when a fire detector is activated,
When the line is long, it is affected by the line resistance, and especially when there are many types of fire detectors to be identified, identification becomes difficult and reliability becomes a problem.

"Means for Solving Problems" This invention is based on the types (sensitivity and type) of fire detectors.
A switch circuit is provided for recovery using recovery signals with different time widths, and the receiver includes a recovery signal generator,
By providing a restoration confirmation section, it is possible to identify the type of fire detector that has activated.

``Function'' Even if there are relatively many types of fire detectors, fire detectors that operate reliably can be identified without being affected by line resistance.

Embodiment An embodiment of the fire alarm system of the present invention will be described with reference to the block circuit diagram shown in FIG. 1 and the timing chart shown in FIG. 2.

In FIG. 1, the fire alarm system of this invention is as follows:
It consists of a fire receiver RC, a pair of lines L and C extending from the fire receiver RC, and a fire detector DE connected between the lines L and C. The fire receiver RC includes a power source E, a winding resistor _R4 such as a relay that detects the operation of the fire detector DE, a recovery pulse generator 3 that can sequentially generate pulses with different pulse widths, and a recovery pulse generator 3 that can sequentially generate pulses with different pulse widths. a transistor Q ₃ that short-circuits the pair of lines L and C based on the voltage, and a recovery confirmation unit 4 that identifies the recovery and type of the activated fire detector DE from the voltage between the pair of lines L and C and the recovery signal. We are prepared. Fire detector DE is
It is comprised of a sensor section 1 that detects phenomena such as heat, smoke, flames, etc. when a fire occurs, and a switch circuit 2 that maintains conduction in response to a detection signal from the sensor section 1. The switch circuit 2 includes resistors R ₁ to ₃ , capacitors C ₁ and ₂ , a PNP transistor Q ₁ , and an NPN
It consists of a type of transistor _Q2 .

Incidentally, a plurality of such fire detectors DE are connected between the pair of lines L and C.

The operation of the fire alarm system of the present invention configured as described above will be explained based on the timing chart of FIG. 2. During normal monitoring, the pair of lines L,
The voltage between C and _VCL is maintained at a predetermined value (generally 24V). When the sensor part 1 of the fire detector DE detects a fire phenomenon, the transistor of the switch circuit 2
Apply a trigger signal to the base of Q ₂ . Transistor Q ₂ becomes conductive and becomes a transistor
_Q1 also becomes conductive and maintains this state. Therefore, at time _T0 , a certain amount of voltage remains between the pair of lines L and C, and a larger current flows than during monitoring. The fire receiver RC detects this current using a relay or the like and notifies the user of the occurrence of a fire using an alarm display (not shown). The switch circuit 2 maintains continuity by keeping the voltages of the lines L and C below a predetermined value (below the holding current) for a period of time determined from the time constants of the resistor R ₁ , capacitor C ₁ and resistor _{R 2 ,} and capacitor C 2. is solved and restored. There are differences in the sensitivity of the sensor unit 1 (classified into 1 to 3 types according to the Fire Service Act), and the type of the sensor unit 1 (ion type or photoelectric smoke detector,
Temperature sensor using bimetal, thermistor, etc.)
The recovery time of the switch circuit 2 is set differently depending on the difference.

The recovery confirmation section 4 of the fire receiver RC is the fire detector DE.
After confirming the operating state, a signal is output to the recovery pulse generator 3. The recovery pulse generator 3 has a pulse width
A pulse of T _A (for example, 7.5 m ^sec ) is generated to turn on transistor _Q3 . The voltage V _CL between the pair of lines L and C becomes almost zero between times T ₁ and T ₂ .
Then, at time _T3 , which is several milliseconds after time _T2 , the restoration confirmation unit 4 determines the state of the fire detector DE from the voltage _VCL . If it has recovered, the type of fire detector DE that was operating is identified, and this identification signal is output to a signal processing circuit (not shown). If the recovery has not been completed, a signal is output to the recovery pulse generator 3.
The recovery pulse generator 3 generates a pulse with the next longest pulse width T _B (for example, 17.5 m ^sec ). The voltage V _CL becomes almost zero between times T ₄ and T ₅ . Then, again at time T ₆ , the recovery confirmation unit 4 judges the state of the fire detector DE, and if it has recovered, it outputs an identification signal for the type of fire detector DE, and if it has not recovered, it outputs an identification signal to the recovery pulse generator 3. Output a signal. The recovery pulse generator 3 outputs a recovery signal with the next longest pulse width T _C (for example, 27.5 m ^sec ). Then, the recovery confirmation unit 4 performs the same operation. In this way, the restoration signals with short pulse widths are sequentially output, and the type of fire detector DE is identified from the restoration state, so it is possible to detect the same type of fire without being affected by the line L and C resistances. Even if multiple DEs are operating, they can be identified at the same time.

Generally, even if the fire detector DE is restored, it will operate again if the sensor unit 1 detects a fire phenomenon. It usually takes some time for the computer to restart after recovery. Therefore, it is only necessary to confirm whether or not the system has been restored between the end of the restoration signal and the re-operation.

For example, the fire detector DE that is restored with a pulse width TA is set to a high-sensitivity smoke detector, the fire detector DE that is restored with a pulse width T _B is set to a low-sensitivity smoke detector, and the If the fire detector DE restored at Width T _C is set to a low-sensitivity heat detector, the alarm device will be activated if a high-sensitivity smoke detector is activated, and the alarm device will be activated if a low-sensitivity smoke detector is activated. The operation of the alarm device is linked with the smoke prevention device. Furthermore, a low-sensitivity heat sensor can be used to configure a disaster prevention system that links the operation of an alarm system and a fire extinguishing system.

"Effects of the Invention" As explained above, the fire alarm system of the present invention does not require a particularly complicated circuit for the fire detector DE, and is free from the influence of the resistance of the lines L and C. Since the type of fire detector DE activated by the RC can be identified, it is possible to provide a highly reliable fire alarm system suitable for interlocking with smoke prevention equipment and fire extinguishing equipment.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing one embodiment of the fire alarm system of the present invention, and FIG. 2 is a timing chart for explaining the operation of FIG. 1...Sensor part, 2...Switch circuit, 3...Recovery pulse generator, 4...Recovery confirmation part, DE...Fire detector, RC...Fire receiver, E...Power supply, _R1 to ₄ ...Resistor,
_C1 , ₂ ...Capacitor, _Q1 ~ ₃ ...Transistor, L,
C...Railway.

Claims (1)

[Scope of Claims] 1. A fire receiver, a pair of lines extending from the fire receiver to a warning area, and a device connected between the pair of lines, and maintaining continuity between the pair of lines at low impedance when a fire is detected. and a plurality of fire detectors that restore the line by a restoration signal that lowers the line current to a holding current, wherein the fire detector is a sensor that outputs a trigger signal when a fire phenomenon is detected. and a switch circuit that maintains continuity between the pair of lines by a trigger signal from the sensor unit, and restores with the recovery signal having a predetermined time width or more that is set differently depending on the type of the sensor unit. The fire receiver includes a restoration signal generation unit that sequentially outputs the restoration signal that lowers the current in the line to a holding current or less, starting from the one with the shortest set time width; and a recovery confirmation unit that detects the recovery state of the fire detector from the voltage between the pair of lines immediately after the output of the recovery signal ends and identifies the type of the fire detector that was operating. Features fire alarm system.