JPS61190693A - Fire alarm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Technical field〕 This invention relates to a fire alarm.

[Prior art]

Conventionally, fire alarms have been equipped with a backup power source, such as a dedicated storage battery, in addition to the main power source, so that they can continue to monitor or issue alarms normally even if the power is cut off.

[Problems with conventional technology]

However, if a fire alarm is equipped with a backup power source like the one mentioned above, the device will be large and expensive, and from a cost perspective, it is desirable to temporarily switch to a normal power source that is being used elsewhere, but even in such cases, IC circuits etc. In recent fire alarm systems that use a large number of devices, there have been problems such as the state of the memory element changes when the power is switched off, and the previous state cannot be reproduced even when the power is turned back on.

[Means for solving problems]

In consideration of the above points, this invention consists of a 0MO3 power source backed up by a capacitor so that the output of the comparator that determines the output state of the fire sensor is maintained even if the power to the fire alarm is momentarily cut off. A D latch and a timer circuit that outputs an output after a predetermined time after power is turned on are provided, the output of the comparator is transmitted to the D latch, and the output of the timer circuit is input to the clock of the D latch. It is characterized by

[For production]

The fire alarm of the present invention has the above-mentioned characteristic configuration, so that even if the power is momentarily cut off, the current state of the fire sensor is retained in the D latch, and this state is retained by the fire sensor's output after the power is turned on again. is changed by the output after stabilizing, so
Immediately after 1i'a is turned on again, the fire alarm is restored to its current correct state.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, S is an ion type fire sensor, which includes inner and outer ion chambers CHI and CH2, and both ion chambers CHI, which are equipped with a pair of electrodes and a radiation source.

It is composed of a current amplifier A whose current increases or decreases depending on the potential of the connection point of CH2, and is constructed so that an analog voltage corresponding to the magnitude of the fire phenomenon is generated in the resistor R of the receiver RE.

The ICI is a comparator for fire detection, and the output from the fire sensor S changes from "H" to "L" at a predetermined value that is determined to be a fire.
The output is configured as an open collector. IC2 is a D latch that transmits or latches the output of the comparator fc1 to the next stage depending on the state of the clock pulse, and is composed of a CMOS with low power consumption, and its clock terminal is connected to the output of a timer circuit TM, which will be described later. B is a storage circuit installed to prevent receiver RE from malfunctioning due to cigarette smoke or electrical noise, which generates an output that indicates that the output of fire sensor S is a fire for a short period of time, and output from D latch IC2. It consists of a charging resistor, a capacitor, and a diode for rapid discharge. IC3 is a self-holding circuit which is operated by the "H" output of the integrating circuit B and whose output changes from "H" to "L", and is composed of a NAND, a NAND, and two NOR circuits having a Schmidt trigger function. IC4 is a buffer circuit.LEDl is a fire indicator composed of a light emitting diode, which is turned on in the event of a fire.

IC5 is a comparator for determining dirt, and its output changes from "Ho" to "L" with a predetermined input value smaller than ICI, which increases the output due to dust accumulated in the fire sensor S and causes the sensor S to malfunction. IC6 is a D-launch that transmits or latches the output of comparator IC5 to the next stage, similar to IC2, and is made of CMOS with low power consumption. The crossshift terminal is connected to a timer circuit TM, which will be described later.
In addition, the Q output is connected to the reset terminal of the self-holding circuit IC3. IC7 is NAN with Schmitt trigger function
In the D circuit, the subsequent timer circuit IC8 is provided so as to be reset by the "H" output of IC6 and reset by the "L" output of IC3. IC8 is a timer circuit provided to determine whether the change in the output of the fire sensor S is due to fire or dirt.The time is selected to be, for example, 5 minutes, and the time is determined by a binary counter and a CR oscillator. After a predetermined period of time, the output changes from "L" to "H".

T' is a transistor for detecting an abnormality such as a short-circuit in the output of the fire sensor S, and is configured to turn off in the ONL short-circuit state in a normal state, and the collector is connected to the transistor Tr'. The collector of ' is connected to the NOR circuit IC9 together with the output of the timer circuit IC8, and its output is connected to the NAND circuit ICl0.
The operation indicator light LE is composed of a light emitting diode through
It is connected to D2 and lights up when the fire sensor S is normal. Furthermore, in Figure 1, 220 is 20
V power supply, PI3. P12H indicates that 12V power is supplied, and PI3. P12H and P
H3 will be explained in detail with reference to FIG.

In Figure 2, DC is a rectified power supply, SC1゜3C2 is 20V (symbol P20) and 12V (symbol P12), respectively.
) is a constant voltage circuit that outputs a constant voltage. C1 is a back amplifier capacitor connected in parallel to the constant voltage circuit SC2 through a diode d, and is configured so that even when the power is cut off, 12V power is supplied from the capacitor C8 (sign P12).TM is Said D latch IC2,I
In the timer circuit that supplies clock pulses to C6, a charging resistor R5 with a discharging diode d2 in parallel is connected in series to the capacitor C2, and their connection point is 12V.
to the base of the transistor TrI via a Zener diode ZD with a Zener voltage of , and the collector to the resistor R
It is connected to capacitor C7 via t. ICII is a NAND circuit composed of CMOS with low power consumption.
When the transistor Tr+ is ON, the output (symbol PH8) is aH1, and when it is OFF, the output is "L".

The set time of this timer circuit TM is selected to be the time when the fire sensor S is powered on and is sufficiently stabilized. The NAND circuit ICII of the timer circuit TM is
As shown on the right side of FIG. 2, these power supplies are supplied from a back amplifier capacitor C2. Although other circuit elements are not shown, PI3 or P2
It is connected to O.

Next, the operation of the fire alarm will be explained.

When the power is turned on, 20V power is supplied to the fire sensor S, and 20V and 12V power are supplied to each circuit element of the receiver RE via the constant voltage circuits SCI and SC2. Furthermore, when the fire sensor S is installed, there is no accumulation of dust and the function is maintained normally, so the outputs of the comparator ICI for fire discrimination and the comparator IC5 for dirt discrimination are both ""H", and the d outputs of D latches IC2 and IC6 become L. As a result, the storage circuit B"L", the self-holding circuit rC3aH"-bar/
77 circuit rc4 becomes "Hl" and the fire indicator light LHDI is turned off.

Also a NAND circuit IC? “Hl, timer circuit IC8L
″, NOR circuit IC9 “H”, NAND circuit IC10
becomes 1L", the operation indicator light LED2 lights up, and it is displayed that the fire sensor S continues monitoring normally.

When a fire occurs and smoke flows into the external ion chamber CH2, and the potential at the connection point between the inner and outer ion chambers drops, a current flows through the current amplifier A accordingly, increasing the voltage drop due to the resistance of the receiver RE. When this voltage reaches a predetermined value, the output of the comparator rcl is inverted from "Hl" to "L" and the output of the D latch IC2 becomes aH.

Then, the b capacitor of the storage circuit B is charged and becomes "H" after a predetermined time, which causes the self-holding circuit IC3 to become 1L'.
, the buffer circuit TC4 becomes “L” and the fire indicator light LE
D1 is lit to indicate that a fire has occurred. In this case, the comparator IC5 for dirt determination also inverts from "H" to "L", and roughly the Q output of D latch IC & changes from "L" to a
The timer circuit IC8 is set through the NAND circuit IC7, but in the event of a fire, the self-holding circuit IC3 is immediately reversed from "H" to "L", so the NAND
The D circuit IC7 becomes ``H'' and the timer circuit IC8 is reset.

However, if the voltage drop across the resistor R gradually increases due to dirt in the ion chamber CH2 of the fire sensor S, and the comparator rC5 reverses from "H" to "L", the output of the fire sensor S may occur in a short period of time. reaches the fire level and sets comparator rC1 to “L”.
”, the timer circuit IC8 remains in the state, and after a predetermined time, its output becomes “Hl”.
becomes. As a result, the NOR circuit IC9 becomes high, the NAND circuit ICl0 becomes H, and the operation indicator light LED2 is turned off, indicating that the fire sensor S is dirty or malfunctioning.

In addition, when i[I[ is cut off in any of the above states, the comparator TCI,
The power supply to IC5, storage circuit B, self-holding circuit [C3, buffer circuit [C4], etc. is stopped, but D-latch IC2, IC6, and ICII are maintained in an operating state using capacitor C2 as a power source. , comparator ICI
The output states of IC5 and IC5 continue to be held at the Q outputs of D latches IC2 and IC6, respectively. Therefore, when the power is turned on again, the outputs of the D latches IC2 and IC6 control the subsequent circuits and immediately restore the state before the power outage.

Also, when the capacitor C2 of the timer circuit TM is charged and the Zener diode ZDr becomes conductive, the transistor Tr+
turns on, and the output of the NAND circuit IC11 becomes "H".

As a result, the output in a stable state after power is applied to the fire sensor S is determined by the comparators ICI and IC5, and the output state is transmitted to the D latches IC2 and IC6.
The display will be displayed accordingly.

In addition, in the above embodiment, open collectors are used for the comparators ICI and IC5, so the fire sensor s side)'r! 1m
Voltage trigger D latch f I C2, 1C6 (D power supply voltage can be arbitrarily selected, and D latch configured with CMOS with low power consumption can be adopted. In this case, the above comparator is an open drain type. In addition, although the above embodiment has been described as a receiver, a repeater may also be used, and the fire sensor may also be of a thermal type or a photoelectric type.

〔effect〕

Since the fire alarm system of the present invention is configured and operates as described above, even if the power is cut off, the output state of the fire sensor S will be D, which has low power consumption and is backed up by a capacitor.
The stable output of the fire sensor S after the power is turned on is transmitted to the output of the D latch by the action of the timer circuit, so even if the power is cut off, the correct state will be immediately restored when the power is turned on again. This has the effect of ensuring that the fire alarm system is restored.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of one embodiment of the fire alarm of the present invention, Figure 2 is the power supply circuit of Figure 1, and circuits IC2 and IC6 of Figure 1.
The connection state with the power supply terminal and the timer circuit are shown. S...Fire sensor, RE...Receiver, IC1, IC
5... Comparator, IC2, IC6... D launch, T
M...Timer circuit, CI...Capacitor.

Claims (1)

[Claims] 1. Phenomena such as heat, smoke, gas, or light caused by a fire are detected by a fire sensor and converted into an electrical analog quantity, and the analog output is detected by a repeater or receiver to prevent a fire. In a fire alarm system that is designed to notify the user, the repeater or receiver is equipped with a D-latch consisting of a comparator that detects a predetermined analog output from the fire sensor and a CMOS that maintains the digital output state of this comparator, and a power supply. A timer circuit that generates an output after a predetermined time is provided, a backup capacitor is connected to the power terminal of the D latch, and the output of the timer circuit is input to the clock terminal. fire alarm. 2. The fire alarm according to claim 1, wherein the comparator is an open collector type comparator. 3. The fire alarm according to claim 1, wherein the comparator is an open drain type comparator.