JPS61216562A - Power failure detecting circuit - Google Patents

Abstract

PURPOSE:To detect the power failure of AC power source quickly by monitoring a DC voltage independently by a photocoupler without being influenced by a smoothing circuit provided in an AC/DC convertor. CONSTITUTION:An output voltage of a rectifier circuit 12 is inputted to the diode 14a of a photocoupler 14. On the other hand, an output of the rectifier circuit 12 is connected to a smoothing circuit 13 through a diode 16 to prevent a reverse current. Accordingly, when a commercial power source 2 is in conductive state, the diode section 14a is energized and the transistor section 14b becomes conductive, and a capacitor 152 becomes the state of discharge. An input voltage of a NOT circuit 153 becomes low, and an output voltage of the NOT circuit 153 becomes high. On the other hand, when an output voltage of the NOT circuit 153 changed to low level, a processor 10 judges that the commercial power source 2 is failed and sets gates 41-4n in a signal separating circuit 4 to cut-off state. Consequently, various information transferred from a basic telephone circuit section 3 to a high-function circuit section 5 is cut off immediately.

Description

[Detailed Description of the Invention] [Summary] By monitoring the DC voltage from the output part of the rectifier circuit of an AC/DC converter, it is possible to maintain a device that is quickly supplied with power in response to interruptions in AC power. .

[Industrial application field]

The present invention relates to a power outage detection circuit capable of quickly detecting an AC voltage power outage in an AC/DC converter.

In addition to basic telephone functions, telephones housed in automatic exchanges have become equipped with advanced functions such as diversifying functions as telephone terminals or being equipped with non-telephone terminal equipment. The electricity supplied from the accommodating switching center is insufficient,
If a tree falls, additional power needs to be supplied from a commercial power source.

This type of terminal equipment is equipped with
Measures are needed to ensure smooth operation using only the power supplied from the accommodating exchange.

[Conventional technology]

FIG. 3 is a diagram showing an example of a conventional power outage detection circuit.
FIG. 4 is a diagram showing an example of a conventional AC/DC converter.

In FIG. 3, the terminal device includes a basic telephone circuit section 3 that has the basic functions of a general telephone, such as a transmitting/receiving function, a selection signal sending function, a calling signal receiving function, etc., and a telephone receiving/receiving function using a speaker, a data terminal device, etc. It is composed of a high-performance circuit section 5 that realizes various high-performance functions such as the installation of a high-performance circuit. Various information exchanged between the basic telephone circuit section 3 and the high-performance circuit section 5 is transferred via the signal lines 61 to 6n and the signal separation circuit 4. The basic telephone circuit unit 3 uses a DC voltage V1 supplied via a subscriber line from an exchange accommodating the terminal device, and a DC voltage V2 generated by rectifying a commercial power supply 2 by an AC/DC converter 1. The high-performance circuit section 5 operates only with the DC voltage v2 supplied from the AC/DC converter 1. Note that the diodes 7 to 9 are provided to prevent mutual interference between the DC voltages V1 and (2).

The AC/DC converter 5 is constructed as shown in FIG. A large-capacity capacitor 13 that outputs a DC voltage v2
1.

When the commercial power supply 2 is interrupted, the capacitor 131 gradually discharges, and the output DC voltage 2 gradually decreases based on a time constant determined by the capacitance of the capacitor 131.

A processor (CPU) 10 is provided in the basic telephone circuit unit 3, and a DC voltage v generated from the commercial power supply 2 is provided.
2, and when it is detected that the DC voltage V2 has fallen below a predetermined value in the event of a power outage in the commercial power supply 2, a gate (41) provided for each signal line 61 to 6n in the signal separation circuit 4 4n to 4n are cut off. As a result, various information is no longer transferred between the basic telephone circuit section 3 and the high-performance circuit section 5. However, after a power outage of commercial power supply 2, the DC voltage
2 falls below a predetermined value, there is a delay based on the time constant of the smoothing circuit including the capacitor.
Various types of information flow from the basic telephone circuit section 3 to the high-performance circuit section 5 via channels 1 to 4n.

[Problem that the invention seeks to solve]

As is clear from the above explanation, in the conventional power failure detection circuit, after the commercial power supply 2 has failed, the processor 1
The delay time until AC/DC converter 1 detects a power outage is
increases due to the large capacity capacitor 131 installed in
During this time, there was a risk that various information would flow from the basic telephone circuit 3 to the high-performance circuit section 5.

Therefore, if various types of information are sent to the high-performance circuit when the commercial power supply is interrupted and the high-performance circuit is in an unstable state, malfunctions may occur.

[Means for solving problems]

The present invention will be explained using the principle block diagram shown in FIG.

In the figure, an AC power supply 2 such as a commercial power supply is connected to a DC voltage 2 via a transformer 11, a full-wave rectifier circuit 12, and a smoothing circuit 13.
is converted to

On the other hand, detection of power failure is performed by the photocoupler 14 and the signal level detection circuit 15 after rectification by the rectification circuit 12.

A diode 16 is provided upstream of the smoothing circuit 13 to prevent reverse flow into the photocoupler 14 .

In the device to which power is supplied, by monitoring the level of the DC voltage v1 using the output signal of the signal level detection circuit 15, the rectifier circuit 12 can be activated without depending on the time constant of the smoothing circuit.
By drawing in the output of , it can be realized with a relatively simple circuit configuration.

[For production]

That is, according to the present invention, the photocoupler can quickly detect a power outage of the AC power supply by independently monitoring the DC voltage without being influenced by the smoothing circuit provided in the AC/DC converter.

〔Example〕

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

FIG. 2 is a diagram showing an AC/DC converter according to an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same objects.

In FIG. 2, the output after passing through the transformer 11 and the rectifier circuit 12 is input to a power failure detection circuit composed of a photocoupler 14, resistors 17 and 151, a capacitor 152, and a negative circuit 153.

The diode section 14a of the photocoupler 14 includes a rectifier circuit 1.
2 output voltages are input. On the other hand, to the smoothing circuit 13,
Connecting the output of the rectifier circuit 12 via a diode 16,
Prevents backflow. Therefore, when the commercial power supply 2 is in a conductive state, the diode section 14a is energized, the transistor section 14b is in a conductive state, the capacitor 152 is in a discharged state, and the input voltage of the inverting circuit 153 is at a low level. The output voltage of 153 becomes high level.

Furthermore, when the commercial power supply 2 is in a power outage state, the diode section 14
a is no longer energized, the transistor section 14b is cut off, and the capacitor 152 is charged by the DC voltage v1 via the resistors 17 and 151. Note that since the capacitor 152 has a sufficiently smaller capacity than the capacitor 131,
The terminal voltage of the capacitor 152 rapidly rises to a high level, and the output voltage of the negative circuit 153 is transmitted to the processor 10 in the basic telephone circuit section 3 via the signal line 18.

The processor 10 monitors the output voltage of the NOT circuit 153 transmitted from the signal line 18, and if the output voltage is set to a high level, determines that the commercial power supply 2 is in the energized state, and switches the signal separation circuit. Each of the gates 41 to 4n in 4 is set to a conductive state. As a result, various information is transferred between the basic telephone circuit section 3 and the high-performance circuit section 5 via the signal lines 61 to 6n. On the other hand, when the output voltage of the NOT circuit 153 changes to a low level, the processor 10
It is determined that there is a power outage, and each gate 41 in the signal separation circuit 4
to 4n are set to the cut-off state. As a result, various information transferred from the basic telephone circuit section 3 to the advanced circuit section 5 is immediately interrupted.

As is clear from the above description, according to the present embodiment, the processor 10 in the basic telephone circuit unit 3 can quickly indicate a power outage in the commercial power supply 2 independently of the capacitor 131 in the AC/DC converter l. Since the commercial power supply 2 is monitored by the output voltage of the circuit 153, a power outage of the commercial power supply 2 is quickly detected, and various information is prevented from flowing from the basic telephone circuit section 3 to the high-performance circuit section 5 after the power outage.

It should be noted that FIG. 2 is only one embodiment of the present invention, and for example, the subject of the present invention is not limited to terminal devices, but is used in cases where it is necessary to quickly detect an AC power outage in an AC/DC converter. It can be used with any device.

〔Effect of the invention〕

As described above, according to the present invention, in the AC/DC converter, an AC power outage can be quickly detected, and appropriate power outage countermeasures can be applied.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a diagram showing an AC/DC converter according to an embodiment of the present invention, Fig. 3 is a diagram showing an example of a conventional power failure detection circuit, and Fig. 4 is a conventional diagram. FIG. 1 is a diagram showing an example of an AC/DC converter. 1; AC/DC converter, 2; Commercial power supply voltage, 11i transformer, 12; Rectifier circuit, 13; Smoothing circuit, 14; Photocoupler

Claims (1)

[Claims] In an AC/DC converter 1 that generates a DC voltage by rectifying and smoothing an AC voltage by a rectifier circuit 12, the output of the full-wave rectifier circuit is input to a photocoupler 14, and the output of the photocoupler A power outage detection circuit that detects a power outage of the alternating current voltage.