JPS60103896A - Trunk line interface circuit - Google Patents

Abstract

PURPOSE:To allow continuation of calling even when power supply is restored during calling through a power-failure calling telephone set line by connecting a simple current detection means to the power-failure calling telephone set line. CONSTITUTION:When commercial power supply is interrupted, a relay switch 4 is reset automatically, and is switched to a contact 4b. A power-failure calling telephone set 3 is directly connected to a binary analogue trunk line 1 through a power-failure calling telephone set line 5, the relay switch 4 and a photo-coupler 6 which is a current detection mechanism, and brought into the condition possible of calling. Since a calling current passes in the photo-coupler 6, a light emission diode emits light continuously, and a signal line 9 is brought into the grounded condition. When power-failure is restored in this condition, a microcomputer 7 is activated. When the signal line 9 includes a ground voltage, the microcomputer 7 identifies that the power-failure calling telephone set 3 is calling, and controls a relay circuit not shown in the figure so as to be supplied with a current continuously, which controls a relay contact 4. At this time the relay contact 4 is not reset, and continuously held at the side of the contact 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a central office line interface circuit for a button telephone device or a private branch exchange. In particular, it relates to a station line interface circuit connected to a two-wire analog station line. Here, the term "one-office line" includes not only public telephone lines but also leased lines and other lines housed in switching equipment.

[Description of prior art]

Conventionally, as a backup measure in the event of a power outage, this main office line interface part has been equipped with a switching circuit that allows a telephone for making calls during a power outage to be directly connected to the office line. was now possible.

However, if the power is restored while the power outage telephone is in the middle of a call, the switching device switches the central office line to the 1-rank circuit regardless of whether the power outage telephone is in use. For this reason, there was a drawback that if the power supply was turned off during a call during a call using the 1-47 phone, the call would be disconnected.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention aims to improve the above-mentioned drawbacks, and aims to provide a central office line interface circuit that allows a user to continue a call even when the power is restored during a call using a power outage telephone.

[Features of the invention]

The present invention provides a switching means for switching between a central office line terminal, a trunk circuit connected to the central office line, and a telephone for use during a power outage in a central office line interface portion of a private branch exchange or key telephone device connected to a two-wire analog central office line; comprising a detection means for detecting the current of the telephone for telephone calls during a power outage, and a control means for controlling the switching means according to the output of the detection means,
The present invention is characterized in that when using a telephone for calling during a power outage, the call can be continued without being disconnected even if the power is restored.

[Explanation based on examples]

Next, a circuit according to an embodiment of the present invention will be described with reference to the drawings. The figure is a block diagram showing the configuration of a station line interface circuit according to an embodiment of the present invention. The office line interface circuit according to the embodiment of the present invention is a PBX connected to a two-wire analog office line terminal 1.
Alternatively, a relay switch 4 for switching between the trunk circuit 2 of the button telephone device and the telephone 3 for making calls during a power outage is connected, and a current detection mechanism is further connected to the telephone connection line 5 for making calls during a power outage connected to the telephone 3 for making calls during a power outage. A photocoupler 6 is connected, and this photocoupler 6 is connected to a microcomputer 7 that controls its output.

The operation of the station line interface circuit according to the embodiment of the present invention configured as described above will be explained. Under normal conditions, the relay switch 4 is connected to the contact point 4a, and the trunk circuit 2 is connected to the two-wire (2)' analog office line terminal 1 for telephone communication. When the commercial power supply is cut off, the relay switch 4 is automatically restored and switched to the contact 4b, and the telephone 3 for making calls during a power outage is activated.
is directly connected to the two-wire analog office line 1 via a line 5 for connecting a telephone for telephone calls during a power outage, a relay switch 4, and a photocoupler 6, and becomes ready for telephone calls.

In this state, the communication current of the office line that flows through the telephone set 3 for telephone calls during a power outage flows through the first coupler 6, so that the light emitting diode continuously emits light, its transistor becomes conductive, and the signal line 9 is grounded. become a state. In this talking state at the time of power outage, the microcomputer 7 does not operate because power is not supplied to it. When the power is restored in this state, the microcomputer 7 starts up. If there is a ground potential on the signal line 9 at this time, it will be recognized that the power outage telephone 3 is in use, and the relay contact 4 will continue to be held at the contact 4b side without being restored. Relay contact 4
Control continues to supply current to a relay circuit (not shown) that controls the current.

When the telephone call ends, the telephone current flowing through the photocoupler 6 disappears, and the ground potential of the signal line 9 disappears.
It can be returned to a consolidated state.

In this way, even if a power outage is restored while a telephone is being used for a power outage, the connection to the line during the call will not be automatically cut off.

In the above example, it was explained that when the power is restored, the relay contacts 4 are held continuously, but by controlling the trunk circuit 2, the office line 1 and the telephone line 5 are directly connected to the I node, and the relay contacts are 4 can also be controlled to be open.

〔Effect of the invention〕

As described above, according to the present invention, 'ili;
By connecting a detection means to the telephone line for telephone calls during power outages, the PBX
Or, if the commercial power supply to the button telephone is restored, the telephone for making calls during a power outage will not be able to be used.
There is an excellent phone call that allows you to continue the call without having to use i-4.

[Brief explanation of the drawing]

The figure shows the configuration of a station line interface circuit according to an embodiment of the present invention. ■...Two-wire analog station line, 2...IIIX [-
1-rank circuit of ``G'' button telephone device, 3... Telephone for calling during power outage, 4... Relay switch, 4a, 4b
...Relay isoji contact point, 5...Telephone connection line for calling during power outage, 6...Photocoupler, 7...Microcomputer. Patent applicant: NEC Corporation Representative Patent attorney: Naotaka Ide

Claims (1)

[Claims] (1) A central office line terminal to which a central office line is connected, a power outage telephone line terminal that accommodates a power outage telephone line for making calls during a power outage, and a power outage telephone line terminal that connects the power outage telephone line terminal to the power outage telephone line terminal during a power outage. In the office line interface circuit equipped with a relay contact, a detection circuit that detects the communication current flowing to the power outage telephone line terminal, and a detection circuit that detects the communication current flowing to the power outage telephone line terminal; and control means for controlling to continue connection with the power outage telephone line terminal.