JPS61167264A - Power failure detecting circuit - Google Patents

Abstract

PURPOSE:To detect a power failure of AC voltage quickly by rectifying the AC voltage independently of a full-wave rectifying circuit, inputting to a photocoupler, and detecting the power failure of AC voltage by an output of the photocoupler. CONSTITUTION:A power failure detecting circuit consisting of diodes 54 and 55, a photocoupler 56, resistances 57 and 58, a capacitor 59 and an NOT circuit 50 is provided. The output voltage of a transformer 51 is rectified in terms of full waves by diodes 54 and 55 and a part of diode of a full-wave rectifying circuit and inputted to the diode section 56d of the photocoupler 56. Accordingly, when a commercial power source is in energizing state, the diode section 56d is energized and a transistor TR56t becomes conductive and the capacitor 59 discharges. Thus, an input voltage of the circuit 50 becomes low and an output voltage of the circuit 50 becomes high. When the power source 6 becomes the state of stoppage, the TR56t is cut off, and the capacitor 59 is charged by DC voltage V1 through resistances 57 and 58. A power failure is made known by detecting this.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power outage detection circuit that can quickly detect 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,
For example, it has become necessary to additionally supply power from a commercial power source.

This type of terminal device requires measures to ensure smooth operation using only the power supplied from the accommodating switching center in the event of a commercial power outage.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional power outage detection circuit.
FIG. 3 is a diagram showing an example of a conventional AC/DC converter.

In FIG. 2, the terminal device includes a basic telephone function section 1 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. It is composed of a high-performance section 2 that realizes various high-performance functions such as installing a terminal device, etc. Various information exchanged between the basic telephone function section I and the advanced function section 2 is as follows:
The signals are transferred via the signal lines 31 to 3n and the signal separation circuit 4. The basic telephone function unit l receives a direct current voltage v1 supplied via the subscriber line from the exchange accommodating the terminal device.
and the DC voltage V2 generated by the AC/DC converter 5 by rectifying the commercial power supply 6.
operates only with the DC voltage V2 supplied from the AC/DC converter 5.

Note that the diodes 7 to 9 are for preventing mutual interference between the DC voltages 1 and 72.

As shown in FIG. 3, the AC/DC converter 5 includes a transformer 51 that receives a commercial power source 6, a full-wave rectifier circuit 52 that full-wave rectifies the output voltage of the transformer 51, and a full-wave rectifier circuit 52 that performs full-wave rectification of the output voltage of the transformer 51. It is equipped with a large-capacity capacitor 53 that smoothes the voltage and generates a DC voltage (2). When the commercial power supply 6 is interrupted, the capacitor 53 gradually discharges, and the output DC voltage v2 gradually decreases based on a time constant determined by the capacitance of the capacitor 53.

A processor (MPU) 11 is provided in the basic telephone function unit 1, and a DC voltage 2 generated from a commercial power supply 6 is provided.
When it is detected that the DC voltage 2 has fallen below a predetermined value in the event of a power outage in the commercial power supply 6, the gates 41 to 4 inserted into each signal line 31 to 3n in the signal separation circuit 4 4n is turned off. As a result, various information is no longer transferred between the basic telephone function section 1 and the advanced function section 2. However, from the time when the commercial power supply 6 is out of power until the DC voltage 2 drops below a predetermined value: a delay based on the above-mentioned time constant occurs; Various information will flow from the basic telephone function section 1 to the advanced function section 2 through 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 6 has failed, the processor 11
The delay time until the AC/DC converter 5 detects a power outage is
Due to the large capacitance capacitor 53 provided in the telephone, there is a risk that various information may flow from the basic telephone function section 1 to the advanced function section 2 during that time.

Means for Solving Problem C] The above problem is solved by rectifying the AC voltage with a full-wave rectifier circuit,
In an AC/DC converter that generates a DC voltage by smoothing it with a large-capacity capacitor, the AC voltage is rectified independently of the full-wave rectifier circuit and input to a photocoupler, and the output of the photocoupler prevents a power outage of the AC voltage. This is solved by the present invention, which is characterized in that it detects.

[Effect]

That is, according to the present invention, since the photocoupler monitors the AC voltage independently of the large capacitor provided in the AC/DC converter, it is possible to quickly detect an AC voltage power outage.

〔Example〕

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

FIG. 1 is a diagram showing an AC/DC converter according to an embodiment of the present invention. Note that the same reference numerals refer to the same objects throughout the plan.

In FIG. 1, a power failure detection circuit is provided which includes diodes 54 and 55, a photocoupler 56, resistors 57 and 58, a capacitor 59, and a negative circuit 50. The output voltage of the transformer 51 is applied to the diode portion 56d of the photocoupler 56. Therefore, when the commercial power supply 6 is in a conductive state, the diode part 56d is energized, the transistor part 56t is in a conductive state, and the capacitor 59 is turned on.
is in a discharge state, the input voltage of the NOT circuit 50 becomes a low level, and the output voltage of the NOT circuit 50 becomes a high level. Further, when the commercial power supply 6 is in a power outage state, the diode section 56d
is no longer energized, the transistor section 56t is cut off, and the capacitor 59 is connected to the resistor 57 due to the DC voltage ■1.
and 58. Note that since the capacitor 59 has a sufficiently smaller capacity than the capacitor 53, the terminal voltage of the capacitor 59 rapidly increases and reaches a high level, and the output voltage of the negative circuit 50 becomes a low level. The output voltage of the negative circuit 5 is transmitted to the processor 1 in the basic telephone function section 1 via the signal line 12. The processor 11 monitors the output voltage of the NOT circuit 50 transmitted from the signal line 12, and when the output voltage is set to a high level, determines that the commercial power supply 6 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 function section 1 and the advanced function section 2 via the signals 1j131 to 3n. On the other hand, when the output voltage of the inverting circuit 50 changes to a low level,
The processor 11 determines that the commercial power supply 6 has failed, and sets each gate 41 to 4n in the signal separation circuit 4 to a cutoff state. As a result, various information transferred from the basic telephone function section 1 to the advanced function section 2 is immediately blocked.

As is clear from the above description, according to the present embodiment, the processor 11 in the basic telephone function unit 1 can quickly display a power outage in the commercial power supply 6 independently of the capacitor 53 in the AC/DC converter 5. The output voltage of the circuit 50 causes the commercial power supply 6 to
Therefore, a power outage of the commercial power supply 6 is quickly detected, and various information is prevented from flowing from the basic telephone function section 1 to the advanced function section 2 after the power outage.

It should be noted that FIG. 1 is merely one embodiment of the present invention; for example, the subject of the present invention is not limited to terminal devices, and is used to quickly detect an AC power outage in an AC/DC converter. Applicable to 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 drawings]

FIG. 1 is a diagram showing an AC/DC converter according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a conventional power failure detection circuit,
FIG. 3 is a diagram showing an example of a conventional AC/DC converter. In the figure, 1 is a basic telephone function section, 2 is a high-performance unit 2 and 31 to 3n are signal lines, 41 to 4n are gates, 51 is a transformer, 52 is a full-wave rectifier circuit, 53 and 59 are capacitors, 54 and 55 is a diode, 56 is a photocoupler, 56d is a diode section, 56t is a transistor section, 5
7. 58 and 60 are resistors, 50 is a negative circuit, ■1 and ■2-U-

Claims (1)

[Claims] In an AC/DC converter that rectifies an AC voltage using a full-wave rectifier circuit and smoothes it using a large-capacity capacitor to generate a DC voltage, the AC voltage is rectified independently of the full-wave rectifier circuit and input to a photocoupler, A power outage detection circuit that detects a power outage of the AC voltage based on the output of the photocoupler.