JPS5844476Y2 - Simple fire alarm - Google Patents

Description

[Detailed explanation of the invention] This invention is a home appliance that houses a fire detector, an alarm such as a bell, and a battery as a power source in one case, and can be easily attached to the ceiling to monitor fires. Regarding simple fire alarms that are often used in

Simple fire alarms equipped with ion or photoelectric smoke detectors are known, but for example, rechargeable alarms use ANr as an oscillator, amplifier, and synchronous circuit.
The main parts of the smoke detection circuit and the alarm circuit that operates the bell etc. are composed of integrated circuits (hereinafter simply referred to as ICs). A comparator was installed to monitor the voltage and issue an alarm if the voltage dropped to a predetermined value.

One end of the battery to be monitored is connected to one input of the cono comparator, and a zener diode is connected to the other input, and the zener voltage is selected to be a predetermined voltage value at which an alarm is issued when the battery is depleted. The comparator was configured to operate and issue an alarm when the Zener voltage of the Zener diode was depleted and dropped below the Zener voltage of the Zener diode.

However, Zener diodes that operate stably at relatively low Zener voltages are expensive, and when manufacturing a large number of switched alarms, it is difficult to obtain Zener diodes with the same Zener voltage, and furthermore, Zener diodes that have a constant Zener voltage Even if a large number of Zener diodes are obtained, the voltage drop at the PN junction of the comparator in the above IC will vary, and the comparator will not always operate at a predetermined value, making it impossible to issue an alarm at the correct battery voltage drop. There wasn't.

In consideration of the above points, this invention cleverly utilizes the characteristics of Zener diodes to create a simple fire alarm system that can issue an alarm when the battery voltage drops to a predetermined value even if there are variations in the characteristics of Zener diodes and ICs. It provides an alarm.

Hereinafter, one embodiment of the simple fire alarm of this invention will be described with reference to FIG. 1, taking a photoelectric type as an example.

In the figure, 1 is a battery as a power source for this alarm, 2 is an IC connected in parallel to the battery 1, and this IC 2 houses an oscillator 3, an amplifier 4, an AND circuit 5, an OR circuit 6 button, and a comparator 7. A light emitting diode 8 as a light source is connected to the oscillator 3 and is configured to pulse light at a constant period, and a solar cell 9 receives the scattered light of the light source caused by the presence of smoke and outputs the light. It is connected to an amplifier 4 for amplification.

The outputs of the oscillator 3 and amplifier 4 are both connected to the input of an AND circuit 5, which is connected to transmit the output of the magnifier 4 synchronized with the lighting of the light emitting diode 80 to the OR circuit 6 at the subsequent stage. A detection circuit is configured.

The output of this OR circuit 6 is connected to the battery 1 outside the IC 2 by the relay A.
The buzzer 1 is connected to the base of the transistor 10 connected in parallel through the
1 is connected in parallel to battery 1 to form an alarm circuit.

Furthermore, the inverting input of the comparator 7 that monitors the voltage drop of the battery 1, which is related to the main part of this invention, is connected to the positive terminal of the battery 1, and the non-inverting input of the comparator 7 is connected to the positive terminal of the battery 1, and the non-inverting input of the comparator 7 is connected to the variable voltage regulator connected in parallel to the battery 1. It is connected to a connection point between pixel elements 12 and 13 of a series circuit of a resistor 12 and a Zener diode 13.

In this case, the zener voltage of the zener diode 13 is a voltage value Va at which the battery 1 is exhausted and the alarm is desired to be issued, as shown in FIG.
The voltage value Vz is selected to be slightly larger than the voltage value Vz.

Next, to explain the operation of the alarm, the light emitting diode 8 is only periodically lit by the output of the oscillator 3, but when smoke is generated due to a fire, the light from the light source is scattered. The scattered light illuminates the solar cell 9, and its output is amplified by the amplifier 4, and together with the output of the oscillator 3, the AN
The D circuit 5 is operated and the transistor 1 is connected via the OR circuit 6.
0 conducts and operates relay A.

Then, the make contact a of this relay A closes and the buzzer 11
is sounded to alert you to the fire.

When the battery 1 is exhausted and its voltage drops to Va, the comparator 7 operates and the transistor 10 is connected via the OR circuit 6.
becomes conductive, and the buzzer 11 sounds to issue an alarm in the same way as in the case of a fire.

In this case, the voltage value of battery 1 that issues an alarm is Va, and I
If the voltage drop at the junction of C2 is △V and the voltage across the Zener diode 130 is Va', even if the above △V varies due to the button on each IC, the operating state of the Zener diode 13 can be controlled by the variable resistor 12. Set it in the resistance change region r, change the resistance value of the resistor 12 within this range, change the voltage Va' across the Zener diode 13, and get Va = V.
Since a'-Δ■ can be kept constant, the comparator 7 operates with a constant voltage drop of the battery 1 even if there are variations in the characteristics of the IC 2 and the Zener diode 13.

Although the above embodiment is a simple photoelectric fire alarm, this invention can also be applied to a simple ion fire alarm equipped with a similar comparator.

Since this invention can be configured and adjusted as described above, it has the effect of providing a simple fire alarm that can correctly issue an alarm when the voltage of the battery drops to a predetermined value.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the simple fire alarm of this invention, and FIG. 2 is a characteristic diagram of a Zener diode used in the embodiment of FIG. 1... is the pond, 2... is the IC, 7... is the pond.
... Comparator, 12 ... Variable resistor for voltage adjustment, 13 ... Zener diode.

Claims (1)

[Scope of utility model registration request] 1. In a simple fire alarm in which a photoelectric or ion type smoke detection circuit, the main parts of the alarm circuit, and a comparator circuit for monitoring the voltage drop of the battery power supply are composed of ICs, one input of the comparator is connected to the A simple fire alarm, characterized in that one end of the battery is connected to the other input to a connection point of a pixel element of a series circuit consisting of a voltage regulating resistor and a Zener diode connected in parallel to the battery. . 2. The simple fire alarm according to claim 1, wherein the voltage regulating resistor is a variable resistor.