JPS5840310B2 - Kandenchinai Izogata Kanchiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor incorporating a dry cell battery as a power source, and an object of the present invention is to provide a sensor that accurately indicates a drop in the voltage of the dry cell battery.

An embodiment of the present invention will be described below with reference to the drawings.

1 is a conventionally known pulse drive type detection circuit for detecting smoke, temperature, etc.; 2 is a pulse oscillation circuit for driving the detection circuit 1; 3 is a dry battery for power supply; 4 is a voltage detection circuit. 5 is a pulse count circuit, 6 is an alarm holding circuit, 7 is an AND gate circuit, and 8 is a monostable multi-biflake.

An example of a specific circuit of the voltage detection circuit 4 is shown in FIG.
It's true.

Then, when the voltage of the dry battery 3 is higher than the voltage set by the Zener diode 9 (゛ state ~) and there is a voltage at the terminal A, the Zener diode 9 is applied to the terminal C.
A base current flows through the transistor in the first stage to make the transistor conductive and its collector voltage decreases, so that the transistors in the second stage and below become non-conductive, and the terminal S becomes high level.

However, in this state, when there is no voltage at terminal a, the transistor controlled by the voltage at terminal a becomes non-conductive, so the voltage at terminal A becomes high level.

That is, when the voltage of the dry battery 3 is higher than the voltage set by the Zener diode 9, the voltage of the terminal A is at the level .

However, when the voltage of the dry battery 3 is lower than the voltage set by the Zener diode 9, no current flows to the base of the first stage transistor. Only during this period, the transistors in the second stage and below are conductive, and the voltage at the terminal becomes low level.

That is, when the voltage of the dry battery 3 becomes lower than the voltage set by the Zener diode 9, a high/low level change occurs at the terminal A in response to the pulse supplied to the terminal a.

An example of the pulse count circuit 5 is shown in FIG.
The output of the voltage detection circuit 4 supplied to the terminal d is counted and obtained as an output at the output terminal e, so that the output is L.

Terminal f is a power supply terminal, g is a clearing terminal of the count circuit 5, and Q is an output terminal of each stage of the count circuit.

The operation of this configuration is as shown in FIG. 4, in which the output pulse A of the pulse oscillation circuit 2 is supplied to the detection circuit 1 and the voltage detection circuit 4.

When the voltage of the dry battery 3 falls below a predetermined value, the output terminal of the voltage detection circuit 4 changes in level between high and low levels as shown in the output terminal SugaB.

At the same time, the monostable multivibrator 8 is activated as shown by C, the AND gate circuit 7 is closed, and the pulse supply for clearing the pulse count circuit 5 is stopped as shown by D.

After that, the pulse count circuit 5 counts a predetermined number of pulses B, and then activates the alarm holding circuit 6 to issue a voltage drop alarm.

Dry batteries generally show the normal voltage even if their capacity decreases when no circuit current flows through them, so a method of checking only the voltage without running an actual circuit current will not properly check the battery.

However, according to the present invention described above, the check is performed while the actual circuit current is flowing.

In addition, since pulses are counted at this time, an alarm is not activated due to instantaneous changes, thus preventing malfunctions.

Furthermore, since the voltage is checked in synchronization with the detection pulse, it has the cumulative effect of significantly reducing current consumption.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a sensor showing one embodiment of the present invention;
FIG. 3 is a circuit diagram showing an example of the voltage detection circuit, FIG. 3 is a circuit diagram showing an example of the pulse counting circuit, and FIG. 4 is a waveform diagram in one embodiment of the present invention. 1...Detection circuit, 2...Pulse oscillation circuit, 3...
Dry battery, 4... Voltage detection circuit, 5... Pulse count circuit, 6... Alarm holding circuit.

Claims (1)

[Claims] 1 A detection circuit for smoke, temperature, etc., a pulse oscillation circuit for driving this detection circuit, a dry battery for power supply,
When the voltage of the dry cell battery drops below a predetermined value, the voltage detection circuit whose output terminal changes from low level to low level is activated after counting this level change a predetermined number of times to warn of a drop in the voltage of the dry cell battery. A dry cell built-in sensor characterized by comprising an alarm holding circuit.