JPH0346592Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an input signal disconnection detection circuit used, for example, to turn on an electronic switch of a standby power supply in the event of a power outage. Its features include two NOR gates, a delay circuit, and With a simple circuit that combines the following, it inputs a detection signal that detects the presence or absence of power supply voltage and generates a control signal for the electronic switch of the standby power supply, and also generates pulses as appropriate in the event of a power outage (when there is no detection signal input). The point is that you can manually control on/off of the electronic switch by inputting it.

Conventionally, for equipment such as radio cassettes that use both AC power and battery power, if a power outage occurs while operating on AC power, the power switch of the equipment must be switched to the battery side (depending on the equipment). ) The drawback was that it could not be switched to battery mode unless the plug was removed from the outlet, causing it to stop working.

The purpose of this invention is to improve such shortcomings of the conventional device, and it is an input signal with a simple circuit configuration that can automatically switch the electronic switch of the backup power supply based on the detection signal that detects the presence or absence of the power supply voltage. The object of the present invention is to obtain a disconnection detection circuit.

An embodiment of this invention will be described with reference to FIG.

Input terminal a of NOR gate NOR1 and input terminal c of NOR gate NOR2 are connected to detection signal input terminal IN.
is connected, and the output terminal Y of the NOR gate NOR2 is connected to the input terminal b of the NOR gate NOR1 via a delay circuit consisting of a resistor _R1 and a capacitor _C1 .

The output terminal X of the NOR gate NOR1 is connected to the control signal output terminal OUT, and the NOR gate
Connected to input terminal d of NOR2.

A DC power supply is connected to the input terminal b of the NOR gate NOR1 and the input terminal d of the NOR gate NOR2 via normally open push switches SW1 and SW2, respectively.

Now, when a signal obtained by rectifying and smoothing the AC power source is input to the detection signal input terminal IN, input terminals a and c
is at H level, output terminals X and Y are at L level.
level, and an L level signal is output to the control signal output terminal OUT.

When a power outage occurs (or when the power signal is removed from the detection signal input terminal IN), all input terminals a, b, c, and d are at L level, and output terminals X and Y are at H level. , since the output signal from output terminal Y is input to input terminal b via a delay circuit, output terminal Y changes to L level before input terminal b reaches the threshold potential, and the circuit is stable in this state. However, an H level signal is output to the control signal output terminal OUT.

Also, during power outage (i.e., the control signal output terminal
When OUT is at H level) Push switch SW
When 1 is pressed momentarily and a DC voltage is input to input terminal b, output terminal X goes to L level, output terminal Y goes to H level, and control signal output terminal OUT goes to L level.
A level signal is output.

Next, when the push switch SW2 is pressed and a DC voltage is input to the input terminal d, the output terminal Y goes to L level and the signal at the control signal output terminal OUT goes to H level.

FIG. 2 shows an example in which the input signal disconnection detection circuit shown in FIG. 1 is used in a flashlight that also serves as an evacuation route indicator light.

If the plug 1 is inserted into an outlet located in an evacuation route in a theater or the like, when a power outage occurs, the control signal output terminal OUT becomes H level, the switching transistor Tr becomes conductive, and the lamp L lights up, illuminating the evacuation route. do.

If the flashlight is unplugged from the outlet, it can be used as a flashlight, and the light can be turned on or off as desired by pressing push switches SW1 and SW2.

When the power is restored, if the plug 1 is inserted into the outlet again, the lamp L will automatically go out and the device will be in a standby state.

As explained above, the input signal disconnection detection circuit of this invention uses a simple circuit configuration that combines two NOR gates and a delay circuit, without using large circuit components such as electromagnetic relays or coils, to reduce the power supply voltage. Inputs the detection signal that detects the presence and generates a control signal for the electronic switch of the backup power supply, and
When there is no detection signal, the manual switch
It is possible to control on/off electronic switches by inputting pulses as appropriate, and is highly effective when used in equipment that requires automatic switching on of backup power in the event of a power outage, such as audio equipment or security lights. It is something to play.

[Brief explanation of drawings]

FIG. 1: A wiring diagram of an input signal disconnection detection circuit according to an embodiment of the invention. FIG. 2: A wiring diagram of a flashlight using the input signal disconnection detection circuit shown in FIG. NOR1 and NOR2...2-input NOR gate, IN...detection signal input terminal, OUT...control signal output terminal.

Claims (1)

[Scope of utility model registration request] The first input terminals of two 2-input NOR gates are connected to the detection signal input terminal that inputs the detection signal that detects the presence or absence of the power supply voltage, and the output terminal of one NOR gate is connected to the output terminal of the other NOR gate via a delay circuit. the second input terminal of the other NOR gate, and the output terminal of the other NOR gate is connected to the second input terminal of the one NOR gate.
and a control signal output terminal, and a pulse for inverting the output by manual operation via a manual switch is input to the second input terminal of both NOR gates. Features an input signal disconnection detection circuit.