JPS61121594A - Trunk line-line interface circuit - Google Patents

Abstract

PURPOSE:To use automatically a general telephone set for extension as a telephone set for power failure call usually and to continue a call even when the electric power source is released during the call by inserting an electric current detecting means into a call line for power failure. CONSTITUTION:In the usual condition of the electric power source, a relay switch 4 is held at a contact 4a side, a trunk circuit 2 is connected to a trunk line terminal 1 and the call is executed. A relay switch 9 is connected to a contact 9a side, a line circuit 8 is connected to a line terminal 3 and the call is executed. When a commercial electric power source is interrupted, the switches 4 and 9 are automatically to a contact 4b and a contact 9b, a general telephone set 10 for extension is connected to a terminal 1 as a telephone set for call at the time of power failure and a call enabling condition is obtained. When the power failure is released in this condition, a micro computer 7 is started. At such a time, when a ground electric potential exists at a signal line 11, the calling of the telephone set 10 is identified by a computer 7, the switches 4 and 9 are not released and a closed circuit condition is held, which are controlled like that.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an interface circuit to which a private branch exchange or key telephone device and a two-wire analog office line/line are connected. The central office line here includes not only public telephone lines but also leased lines and RGJ lines accommodated in switching equipment.

[Conventional technology]

The conventional central office line/line interface circuit includes a switching circuit on the central office line interface side that allows a telephone for telephone calls during a power outage to be directly connected to the central office line, so that when the power is cut off, the telephone for telephone calls during a power outage can be used to make telephone calls over the central office line.

However, when power is restored while the power outage telephone is in use, the switching circuit switches the central office line to the trunk circuit, regardless of whether the power outage telephone is in use.

[Problem that the invention seeks to solve]

Therefore, such a conventional circuit has the disadvantage that when the power is restored while the telephone is in the middle of a telephone call during a power outage, the telephone call is disconnected. In order to avoid this, a dedicated telephone set for use during power outages must be installed, which has the disadvantage of being uneconomical.

The present invention aims to improve the above-mentioned drawbacks by using a regular telephone that is normally used for the line of a private branch exchange or key telephone device as a telephone for making calls during a power outage only in the event of a power outage, and making calls using this telephone for making calls during a power outage. The purpose of the present invention is to provide a station line/line interface circuit that allows communication to continue even when power is restored during operation.

[Means for solving problems]

The present invention is a central office line/line interface circuit inserted in each of the paths between the trunk circuit of a switching device and a two-wire analog central office line, and the path between the line circuit of this switching device and a telephone set. As a means for solving the problem, a central office line terminal connected to the two-wire analog office line, a line terminal connected to the telephone set, a power outage call line that bypasses the switching device, and the above-mentioned a first switching means for connecting the office line terminal to either the trunk circuit or the power outage call line; and a second switching means for connecting the line terminal to either the line circuit or the power outage call circuit. a switching means, a detection means for detecting a communication path current passing through the communication circuit during a power outage, and a control means for controlling the first switching means and the second switching means based on the output of the detection means. It is characterized by having the following.

[For production]

When the power supply is normal, the office line terminal and the trunk circuit are connected via the first switching means, and the line circuit and the telephone are connected via the second switching means, and the telephone and the office line are connected. Connected via switching equipment.

When the switching equipment is in a power outage, the office line terminal and the power outage call line are connected via the first switching means, and the power outage call line and the telephone are connected via the second switching means, so that the telephone and the central office line are connected via a power outage call line that bypasses the switching equipment.

When the power is restored to the exchange equipment during a call in this connected state, the communication current is detected by the detection means and this output is given to the control means, and either the connected state is maintained or the connected state when the power supply is normal. controlled by the state.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit according to an embodiment of the present invention will be described below with reference to the drawings.

The figure is a block configuration diagram showing the configuration of a circuit according to an embodiment of the present invention. First, the configuration of a circuit according to an embodiment of the present invention will be explained based on the drawings. In the circuit according to the embodiment of the present invention, the two-wire analog office line terminal (
Hereinafter, it will be referred to as a station line terminal. ) ■ Connected to. A relay switch 4 for switching between a trunk circuit 2 of a private branch exchange or a key telephone device and a call line 5 during a power outage is connected, and
Analog two-wire extension line circuit (hereinafter referred to as line circuit) 8 of a private branch exchange or button telephone device connected to analog telephone line terminal (hereinafter referred to as line terminal) 3 for general telephones for extensions and call line 5 during power outage A photocoupler 6 is inserted into the power outage communication line 5, and the output of the photocoupler 6 is connected to the input of the microcomputer 7.

Next, the operation of the station line/line interface circuit of the present invention will be explained based on the drawings.

In the normal state of the power supply, the relay switch 4 is held at the contact 4a side, and the trunk circuit 2 is connected to the office line terminal 1 for telephone communication. In addition, in the relay switch 9, the contact 9
The line circuit 8 is connected to the line terminal 3 and a telephone call is made.

If the commercial power is cut off in this state, relay switch 4
is automatically switched to the contact 4b side, and the relay switch 9 is automatically switched to the contact 9b side. It is then connected to the central office line terminal 1 via the relay switch 4 and becomes ready for communication. In this state, the office line communication current to the extension telephone 10, which is used as a telephone for telephone calls during a power outage, passes through the photocoupler 6, causing the light emitting diode to emit light, the transistor to conduct, and the signal line 11 to be grounded. become.

In this talking state at the time of power outage, the microcomputer 7 does not operate because power is not supplied to it.

If the power is restored in this state, the microcomputer 7
is activated. At this time, if there is a ground potential on the signal line 11, the microcomputer 7 causes the telephone 1 to
It is identified that 0 is busy, and relay switch 4 is activated.
Relay contacts 4b and 9 continue without being restored.
It is controlled so that a closed state is maintained on the b side. When the call ends, the communication current passing through the photocoupler 6 disappears and the ground potential of the signal line 11 disappears, so the microcomputer 7 changes the connection state between the extension telephone 10 and the office line terminal 1 to the normal state. The connection status will be restored.

In this embodiment circuit, when the power is restored, relay contacts 4b and 9b continue to be held, but trunk circuit 2 and line circuit 8 are controlled to immediately connect office line 1 and line circuit 8, relay contact 4b and The present invention can also be carried out by controlling 9b to be open.

〔Effect of the invention〕

As described above, by inserting a simple current detection means into the line for making calls during a power outage, the present invention enables a general telephone that is normally used for an extension line to be automatically used as a telephone for making calls during a power outage. This has the excellent effect that when the commercial power supply is restored during a telephone call during a power outage, the telephone call can be continued without being disconnected.

[Brief explanation of drawings]

The figure is a block configuration diagram showing the configuration of a station line/line interface circuit according to an embodiment of the present invention. ■... Office line terminal, 2... Trunk circuit, 3... Line terminal, 4.9... Relay switch, 4a, 4b, 9
a, 9b... Relay contact, 5... Call line during power outage,
6... Photocoupler, 7... Microcomputer, 8... Line circuit, 10... General telephone for extension,
11...Signal line.

Claims (1)

[Claims] (1) In the office line/line interface circuit inserted in each of the routes between the trunk circuit of the switching equipment and the two-wire analog office line, and the route between the line circuit of this switching equipment and the telephone set, the above two A central office line terminal connected to the analog central office line, a line terminal connected to the telephone set, a power outage call line bypassing the switching equipment, and a power outage call line connecting the office line terminal to the trunk circuit and the power outage call line. a first switching means that connects the line terminal to either one of the line circuit and the power outage communication circuit; and a communication path that passes through the communication circuit during a power outage. A station line/line interface circuit comprising: a detection means for detecting current; and a control means for controlling the first switching means and the second switching means based on the output of the detection means. .