JPH01164221A - Power failure detection circuit - Google Patents

Abstract

PURPOSE:To reduce influence of noise and power consumption of a power interruption detector, by full-wave rectifying an AC input voltage and applying the full-wave rectified voltage onto a photo-coupler then detecting power interruption based on a signal at the output side of the photo-coupler thereby providing the control power source for the power interruption detector through the power source for a controller. CONSTITUTION:An AC source input Vac is full-wave rectified through a full- wave rectifier 1 then provided to a photo-coupler PC. Output from the photo- coupler PC is shaped through a comparator 2 then provided to a timer circuit 3. The timer circuit 3 judges that power is interrupted if the output from the comparator 2 is turned OFF for longer than a predetermined time, and provides a power interruption detecting signal PB th a controller. Since the control power source Vcc for a circuit at the right side of the photo-coupler PC is fed with power from power source equipment at the side of the controller, power consumption of the power interruption detector is quite low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power outage detection circuit for a robot control device, etc., and particularly to a power outage detection circuit that is less affected by AC power input noise and has low power consumption.

[Conventional technology]

For power supplies for robot control equipment, etc., in order to smoothly restore the system after a power outage, it is necessary to detect the disconnection of AC power input as soon as possible, and to handle the power outage before the stabilized DC power supply for the logic goes out. There is.

FIG. 4 shows an example of such a conventional power outage processing circuit. In the figure, Vac is AC power input, ■ is a full-wave rectifier circuit,
2 is a comparator circuit for detecting a voltage drop, 3 is a timer circuit for detecting voltage drop time and outputting a power failure detection signal PB, and PC is a photocoupler for insulation from the control device. 4 is a stabilizing circuit for supplying power to the comparator circuit 2 and the timer circuit 3, and D is a diode.

[Problem that the invention seeks to solve]

However, in the conventional power failure detection circuit as shown in FIG.
There is a problem in that it is easy to malfunction due to the noise that comes on the signal c.

Furthermore, although the control power supply to the comparator circuit 2, timer circuit 3, etc. in Fig. 4 is low voltage, the AC power input is 10V.
Since the voltage is high, such as 0 to 200V, the power consumption of the stabilizing circuit 4 becomes large, and heat generation of these power failure detection circuits becomes a problem.

The present invention has been made in view of these points, and it is an object of the present invention to provide a power failure detection circuit that is less affected by noise of AC power input and has low power consumption.

[Means for solving problems]

In order to solve the above problems, the present invention detects a drop in AC input voltage, uses a timer to detect that the AC input voltage drop has continued for a certain period of time, and outputs a power outage signal. A power outage characterized in that control power to the detection circuit is supplied from the control device side, AC input voltage is full-wave rectified and input to a photocoupler, and a drop in the AC input voltage is detected from the output of the photocoupler. A detection circuit is provided.

[Effect]

The AC input voltage is full-wave rectified and applied to the LED side of the photocoupler. A power outage is detected using the signal from the transistor on the output side of the photocoupler.

Therefore, the photocoupler blocks noise coming onto the AC input voltage and reduces the influence of noise.

Moreover, since the control power to the power failure detection circuit is supplied from the power supply of the control device, the power consumption of the power failure detection circuit is reduced.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a conceptual diagram of a power failure detection circuit according to an embodiment of the present invention. In the figure, Vac is an alternating current power supply, and ■ is a full-wave rectifier circuit, and the full-wave rectified voltage is input to the photocoupler PC. Therefore, the output of the photocoupler PC can be a pulsed signal with twice the frequency of the AC input.

The output of the photocoupler PC is shaped into a waveform by the comparator circuit 2 and inputted to the timer circuit 3. If the output of the comparator 2 is off for more than a certain period of time, the timer circuit determines that there is a power outage and sends a power outage detection signal PB to the control device.

FIG. 2 shows a time chart representing waveforms of various parts of the power failure detection circuit of FIG. 1. Vac is an AC power input, and it is assumed that there is a power outage at time Ta. Vr is the output of the full-wave rectifier circuit 1, and Vc is the output of the comparator 2, which are waveform-shaped to have a pulse-like waveform. When the signal Vc is on, the AC power input is below a certain value. When the AC power source Vac experiences a power outage at time Ta, the output Vc of the comparator circuit 2 turns on, and the timer circuit 3 measures this, and when a certain amount of time has elapsed, a power outage detection signal PB is detected at time Tb, and the control device send to

FIG. 3 shows a circuit diagram of a power failure detection circuit according to an embodiment of the present invention. Although the diagram roughly corresponds to FIG. 1, there are some parts that do not necessarily match the conceptual diagram. In the figure, Vac is an AC power input, T is a transformer, and Db is a diode bridge.

PC is a photocoupler, and the output of the diode bridge Db is connected in series with the resistor R1 on the diode side.

2 is a comparator circuit, in which the output of the photocoupler PC is connected to a resistor R2 and input to the comparator Com1. The other terminal of comparator Com1 is resistor R
3 and a reference voltage determined by resistor R4, and when the output of photocoupler PC is below this voltage, the output of comparator C0m1 is at a high level.

3 is a timer circuit, and the output of the comparator Com1 is connected to the timer circuit 3 via a diode D2 and a resistor R5. Resistors R6 and R7 are resistors that control the base current of the transistor Tr, and in a normal state, the capacitor Ct is connected via the diode D2 and the resistor R5.
It is in a discharge state by the comparator Com1. However, when a power outage occurs, the output of the comparator C0m1 becomes high level and is charged through the variable resistor Re connected to the emitter of the transistor Tr. Therefore, if the power outage continues for a certain period of time, the capacitor Ct
When the voltage becomes higher than the voltage determined by the resistors R8 and R9, the output of the comparator Com2 becomes high level, and the power failure detection signal PB is detected and output. The control device receives this power outage detection signal PB and performs power outage processing.

If you want to change the time to detect a power outage, use variable resistor RNR.
This is done by changing the resistance value of e.

In addition, the control power supply Vcc of the circuit on the right side of the photocoupler PC
Since is supplied from the power supply device on the control device side, the power consumption of this power failure detection circuit is extremely small, and it can be mounted on the same printed board etc. as other elements.

〔Effect of the invention〕

As explained above, in the present invention, the AC input voltage is full-wave rectified and applied to the photocoupler, and a power outage is detected by the signal on the output side of the photocoupler, and the control power to the power outage detection circuit is supplied to the control device. Since the power is supplied from the power supply, the photocoupler blocks noise that comes on the AC input voltage, reduces the influence of noise, and reduces the power consumption of the power failure detection circuit.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of the power failure detection circuit of the present invention, and Figure 2 is a conceptual diagram of the power failure detection circuit of the present invention.
FIG. 3 is a circuit diagram of a power outage detection circuit according to an embodiment of the present invention, and FIG. 4 is a circuit diagram of a conventional power outage processing circuit. 1----------1/Full-wave rectifier circuit 2--
・−・−−−−−−−−Comparator circuit 3−−−−
−−・−・・・−Timer circuit PC−・−・−・−・・−
・・Photocoupler Com1−・・・・Comparator Com2−・−・Comparator Ct−・−・−1−−−−−−−−・Capacitor Patent Applicant FANUC Co., Ltd. Agent Patent Attorney Takeiwa Hattori Figure 1

Claims (1)

[Claims] (1) In a power outage detection circuit that detects a drop in AC input voltage, uses a timer to detect that the AC input voltage drop continues for a certain period of time, and outputs a power outage signal, the control power to the power outage detection circuit is connected to the control device. What is claimed is: 1. A power outage detection circuit, comprising: supplying an AC input voltage from the AC input voltage source, full-wave rectifying the AC input voltage and inputting the AC input voltage to a photocoupler, and detecting a drop in the AC input voltage from the output of the photocoupler.