JPH0748760B2 - Communication device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a communication device.

[Conventional example]

Conventionally, in this type of device, for example, a telephone or a facsimile machine, the line of the telephone line is captured as follows.

FIG. 2 is a diagram showing a general example in which a DC circuit of a telephone line is opened and closed by controlling a relay with software. That is, since the single stable type is used as the relay, when the power supply from the main power supply is cut off, the DC circuit is inevitably opened, but while the DC circuit is closed, the relay It was necessary to energize the coil, which was disadvantageous in terms of power consumption.

On the other hand, FIG. 3 is a diagram when the single stable relay of FIG. 2 is replaced with a latching type. In this case, it suffices to energize the set coil or the reset coil only when the relay coil is connected or disconnected, and it does not consume current at all times, which is advantageous in terms of power consumption, but some abnormality occurs. When an unexpected power supply stop from the main power source occurs, there is a risk that the DC circuit may remain closed and out of control, which is not preferable in terms of security.

〔Purpose〕

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional example, and to provide a communication apparatus which has low power consumption, a simple configuration, and which does not become out of control while the line is closed and has no security problems. .

〔Example〕

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

FIG. 1 is a diagram showing the configuration of the present embodiment, in which 1 is a connection terminal to a telephone line, 2 is a set coil of a latching relay, 3 is a reset coil, and the relay is turned on by energizing them for a certain time. Connect and disconnect. 4 is a line load such as a modem or a telephone circuit, 5 is a driver of a relay coil, 6
Is a set coil control circuit, 7 is a reset coil control circuit, 8 is a power cutoff detection circuit for detecting power cutoff, and energizing the reset coil for a certain time, 9 is a central processing unit (CPU)
Etc.), 10 is the main power supply for supplying power to the central processing unit and relays, 11 is the auxiliary power supply for energizing the reset coil when the main power supply is cut off, 12 is the latching relay, and 13 is the main power supply.
ON / OFF switch, 14 is a switching element for supplying the current from the sub power supply to the reset coil when the power cut detection circuit detects the main power OFF, 15 is the power cut detection circuit 8 and 11 sub power supply and This is a combination of 14 switching elements, and will be referred to as a relay reset circuit when the main power is cut off.

When the main power supply is turned on, a current is supplied from the main power supply to each relay coil by each of the coil control circuits 6 and 7 and the relay driver of 5 based on a command from the central processing unit 9 Is activated and the DC circuit is opened and closed.

On the other hand, when the main power supply is turned off due to the operation of the 13 main power supply ON / OFF switch, etc.
The switching element of (3) is activated, the reset coil of (3) is energized from the auxiliary power source for a specified time, the relay is activated, and the DC circuit is opened.

Fig. 4 shows a circuit example of the relay reset circuit 15 when the main power is cut off. The resistors 18 and 20 and the capacitors 19 correspond to the power failure detection circuit 8 and the transistors 21 correspond to the switching elements 14.

That is, when the main power supply voltage decreases, the base current is supplied to the 21 transistors by starting the charging of the 19 capacitors, and the 21 transistors remain for the time determined by the resistance value of 18 and the value of the capacitor of 19. It turns on and the current from the sub power supply is supplied to the reset coil. 20 is
This is the discharge resistor for the 19 capacitors.

FIG. 5 is a diagram showing a modification of the relay reset circuit when the main power is cut off, which is a basic part of this embodiment. That is, when the main power source is in the ON state as the sub power source, a capacitor charged by the power from the main power source is used. Capacitor 24 is charged via diode 23 when the main power supply is ON. When the main power supply is turned off, a potential difference is generated across both ends of the resistance of 22 and the base current is supplied to the transistor of 21 so that the transistor is turned on and the charge charged in the capacitor of 24 is supplied to the reset coil, and the DC Open the circuit.

As explained above, by providing a circuit that detects the disconnection of the main power supply and energizes the reset coil with the electric power from the sub power supply, it is possible to prevent the DC circuit opening / closing control by the software using the latching relay. It is possible to eliminate the security problem that the existing DC circuit becomes uncontrollable with the DC circuit closed, and it becomes impossible to control the DC circuit opening / closing with low power consumption.

The DC circuit opening / closing control of this embodiment can be implemented in all communication devices such as facsimile equipment, teletex, telephones, etc. that communicate using a telephone line. In this case, the equipment of this embodiment is connected to the facsimile communication section. , A teletex communication part, a call part, etc. will be connected.

[Effect]

As described above, according to the present invention, it is possible to provide a highly safe communication device with a simple configuration.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of this embodiment, FIG. 2 is a diagram showing a conventional example using a single stable relay, FIG. 3 is a diagram showing a conventional example using a latching relay, and FIG. FIG. 5 is a diagram showing an example of the main power-off relay reset circuit of this embodiment, and FIG. 5 is a diagram showing a modification of the main power-off relay reset circuit. 1 is a telephone line connection terminal, 2 is a set coil, 3 is a reset coil, 4 is a line load, 5 is a relay driver, 6 is a set coil control circuit, 7 is a reset coil control circuit, 8
Is a power failure detection circuit, 9 is a central processing unit, 10 is a main power supply, 11
Is a sub power supply, 12 is a switching relay, 13 is a main power ON / OFF switch, 14 is a switching element, 15 is a relay reset circuit when the main power is off, 16 is a single stable relay, 17 is a coil control circuit, 18 is a resistor, 19 is a capacitor, 20 is a resistor,
21 is a transistor, 22 is a resistor, 23 is a diode, and 24 is a capacitor.

Claims (1)

[Claims] 1. A line capturing means for capturing a line, a control means for controlling the line capturing means, a main power source for supplying power to the control means and the line capturing means, and the main power source. And a supply means for supplying a reset signal to the line capturing means so that the line is disconnected when the power is turned off. The supply means supplies the reset signal for a predetermined time when the main power supply is turned off. A communication device having the capacitor of.