JPH09200344A - Central office trunk circuit with dial-in switching function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts for a central office trunk circuit with dial-in switching function at a private branch exchange. SOLUTION: In a usual state to perform private exchange, a switch part 61 of a dial-in switching circuit 60 connects a station exchange 5 with a central office trunk circuit 50 and connects a subscriber circuit 3 with a telephone set 4. In a dial-in switching state, the switch part 61 directly connects the telephone set 4 and the station exchange 5 and opens a channel. There is one busy monitor circuit, the state of speaking between the telephone set 4 and the station exchange 5 in both the usual state and the dial-in switching state is monitored, and the result is applied to a control circuit 62. Thus, when the telephone set 4 and the station exchange 5 are just under speaking, until that speaking is finished, the dial-in switching state and the usual state can be prevented from being switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a central line trunk circuit with a direct switching function having a function of forming a direct communication between a central office and a telephone when the power is turned off in a private branch exchange. is there.

[0002]

2. Description of the Related Art FIGS. 2 and 3 are circuit diagrams (Nos. 1 and 2) for explaining a conventional direct communication switching circuit. The conventional direct switching circuit 1 of FIG. 2 is realized by a package different from the office line trunk circuit 2, and the direct switching circuit 1 is connected to the subscriber circuit 3 or the telephone 4 by a connector cable or the like. ing. The line from the central office switch 5 is connected to the direct communication switching circuit 1. The office line trunk circuit 2 and the subscriber circuit 3 are connected via an exchange switch (not shown). In recent years, there has been an increasing demand for miniaturization and high-density mounting of the device, and as shown in FIG. 3, a product in which the direct communication switching circuit 1 is incorporated in the office line trunk circuit 2 is also commercialized. FIG. 4 is a circuit diagram showing the direct communication switching circuit in FIG. 2 or FIG. 3, and FIG. 5 is a circuit diagram showing the direct communication switching circuit with the busy monitoring function. 4 and 5, elements common to those in FIG. 1 or 2 are designated by common reference numerals. The direct communication switching circuit 10 shown in FIG. 4 and the direct communication switching circuit (EM
G) 20 are all office line trunk circuits (TRK) 2
Is provided between the central office switch (CO) 5, the subscriber circuit (SLIC) 3, and the telephone (TEL) 4.

The direct line switching circuit 10 switches the line state between the telephone 4 and the central office switch 5, and includes a switch section 11, a switching input signal circuit 13 connected to a control circuit 12 of a host device, and a voltage. And a monitoring circuit 14.
The switch unit 11 uses a plurality of switches provided therein to provide a function of connecting the telephone set 4 and the central office switch 5 via the central line trunk circuit 2 and the subscriber circuit 3, and a function of directly connecting them. Have The state of FIG. 4 is a state in which the telephone 4 and the central office 5 are directly connected. The voltage monitoring circuit 14 and the switch unit 11 are connected to the switching input signal circuit 13. When the switching input signal circuit 13 sends a switching signal to the switch unit 11 and the activated switching signal is given to the switch unit 11, the telephone 4 and the central office switch 5 are directly connected (direct switching state). . When the switching signal is inactive, the telephone 4 and the central office 5 are connected via the central line trunk circuit 2 and the subscriber circuit 3 (normal state). In the direct switching circuit 10, the telephone 4 and the central office switch 5 are simply based on the instruction from the control circuit 12.
The line state between the two is changed, or the line state is changed based on the voltage monitoring result by the voltage monitoring circuit 14. In this case, the direct communication switching state returns to the normal state according to an instruction from the control circuit 12 or autonomously returns to the normal state due to the restoration of the power source, so that the call in progress at that time is forcibly terminated. To prevent this, the direct communication switching circuit 20 of FIG. 5 is provided with a busy monitoring circuit 21 (SPV). The parts of the direct communication switching circuit 20 other than the busy monitoring circuit 21 have the same configuration as the direct communication switching circuit 10.
The busy monitoring circuit 21 is composed of a fort coupler or the like for monitoring a loop current during a call, and the busy monitoring circuit 21 monitors a loop current of a line directly connecting the telephone 4 and the central office 5. ,is set up.

In the direct communication switching circuit 20, even if an instruction for canceling the direct communication switching is received from the host device, if the line is busy, the direct communication switching state is maintained until the communication ends. FIG. 6 is a circuit diagram showing the internal structure of the office line trunk circuit. The office line trunk circuit 30 has a line signal monitoring circuit (SPV) 31 for monitoring the loop current of the line from the central office switch 5. The line signal monitoring circuit (SPV) 31 monitors the communication state between the telephone 4 and the central office 5 in the normal state. The line signal monitoring circuit 31 is also composed of a Fort coupler or the like like the busy monitoring circuit 21, and is arranged on one of the two lines forming a line with the central office switch 5.
Of the two wires, the other wire has a DC cut capacitor 32.
Is connected. A DC load circuit (L
OOP) 33 and a switch 34 are connected in series, and a ringing loop load resistor 35 and a switch 36 are further connected.
Are also connected in series. A 2-wire 4-wire conversion circuit (HYB) 37 is connected to the 2-wire private branch exchange switch side (not shown). The direct line switching circuit 20 having the busy monitoring function as shown in FIG.
It is incorporated in the same package as 0 to form a direct line switching function-equipped office line trunk circuit.

[0005]

However, the conventional office line trunk circuit with a direct switching function has the following problems. Even if the direct line switching circuit 20 is incorporated in the office line trunk circuit 30 in response to the demand for downsizing and high density mounting, the station line trunk circuit 30 and the direct line switching circuit 20 are independent circuits, and From the point of view of streamlining points, it was not technically satisfactory.

[0006]

In order to solve the above problems, the present invention is formed by incorporating a direct switching circuit for opening a direct call between a central office and a telephone by switching an internal switch in the same package, A direct line switching function-equipped office line trunk circuit serving as an interface of a private branch exchange to the central office exchange has the following configuration. That is, the central line trunk circuit with a direct switching function of the present invention monitors the line to detect the call state between the central office and the telephone, and controls the switching of the internal switch of the direct switching circuit based on the detection result. The busy monitoring circuit that informs the control means to
It is arranged between the central office and the internal switch. According to the present invention, since the office line trunk circuit with the direct switching function is configured as described above, the direct switching circuit sets the direct switching state or the normal state by switching the internal switch. Here, the busy state monitoring circuit monitors the call state between the central office and the telephone in the normal state and the call state between the central office and the telephone in the direct switching state, and the detection result is given to the control means. The control means controls the internal switch of the direct communication switching circuit at a timing according to the detection result of the busy monitoring circuit to switch between the direct communication switching state and the normal state.

[0007]

1 is a circuit diagram of an office line trunk circuit with a direct switching function showing an embodiment of the present invention.
The common reference numerals are given to the elements common to the elements in FIG. This office line trunk circuit with direct switching function 40
Is provided with an office line trunk circuit (TRK) 50 and a direct line switching circuit (EMG) 60, and is connected between a central office switch (CO) 5, a subscriber circuit (SLC) 3 and a telephone (TEL) 4. The central office trunk circuit 40 serves as an interface to the central office exchange 6 by a private branch exchange, and is connected to the line from the central office exchange 5. A DC cut capacitor 51 is connected to one of the two lines forming the line from the central office 5. A DC load circuit (LOOP) 52 and a switch 53 are connected in series between the two lines, and a ringing loop load resistor 54 and a switch 55 are also connected in series. Two-line central office switch 5
A two-wire to four-wire conversion circuit (HYB) 56 is connected to the side opposite to the side, that is, on the side of a private branch exchange switch not shown. The direct switching circuit 60 switches the line status between the telephone 4 and the central office 5, and includes a switch unit 61 and
Switching input signal circuit (SIN) 63 connected to the control circuit (CTL) 62 of the host device, and voltage monitoring circuit (DET)
64 and a busy monitoring circuit (SPV) 65. The switch section 61 uses a plurality of switches provided therein to connect the telephone 4 and the central office 5 to the central office trunk circuit 2
And a function of connecting via the subscriber circuit 3 and a function of directly connecting the telephone 4 and the central office 5 to open a direct communication. The control of the switch section 61 is performed by a control circuit 62 and a switching input signal circuit 63 which constitute a control means. In the state of FIG. 1, the telephone 4 and the central office 5 are directly connected. A voltage monitoring circuit 64 is further connected to the switching input signal circuit 63. When the switching input signal circuit 63 sends a switching signal to the switch section 61 and the activated switching signal is given to the switch section 61, the telephone 4 and the central office switch 5 are directly connected (direct switching state). . When the switching signal is inactive, the telephone 4 and the central office 5 are connected via the central line trunk circuit 2 and the subscriber circuit 3 (normal state). The busy monitoring circuit 65 is composed of a fort coupler or the like for monitoring a loop current during a call, and the busy monitoring circuit 61 is arranged between the switch unit 61 and the central office 5. Next, the operation of the office line trunk circuit 40 with a direct switching function shown in FIG. 1 will be described.

In a normal state, the switch section 61 in the direct switching circuit 60 connects the line from the central office switch 5 to the central line trunk circuit 50, and connects the line between the subscriber circuit 3 and the telephone set 4. In this normal state, the central office trunk circuit 50 functions as an interface to the central office switch 5 of the private branch exchange, and the switch (not shown) and the subscriber circuit 3 are shown.
A call path between the central office 5 and the telephone 4 is set via the. In the normal state, when the central office switch 5 and the telephone 4 are busy, it is detected by the busy monitoring circuit 65,
The control circuit 62 is notified. The direct communication switching circuit 60 changes the line state to the direct communication switching state based on an instruction from the control circuit 62 or a voltage monitoring result by the internal voltage monitoring circuit 64. That is, a plurality of switches of the switch unit 11 are changed over, whereby a call path between the telephone 4 and the central office 5 is opened. In this direct communication switching state, the monitoring result of the busy monitoring circuit 65 is given to the control circuit 62 as a direct communication switching busy signal. For example, even if there is a request to restore the power of the private branch exchange or to release the direct switching state, the control circuit 62 and the switching signal input circuit 63 maintain the direct switching state with respect to the switch unit 61 until the call ends. Control. That is, the call in progress does not forcibly end. As described above, in the present embodiment, the busy monitoring circuit 6
Since 5 is arranged between the switch section 61 and the central office 5,
Conventionally, the busy state monitoring circuit 21 and the line signal monitoring circuit 31 are used to monitor only the busy state monitoring circuit 65 for the call state of the central office 5 and the telephone 4 in the normal state and the direct switching state. Can be done at. Therefore, the number of parts of the direct line switching function-equipped central line trunk circuit can be reduced, and further miniaturization and high-density mounting can be further advanced.

[0009]

As described in detail above, according to the present invention, in the office line trunk circuit with the direct switching function formed by incorporating the direct switching circuit in the same package, the communication state between the central office and the telephone set can be improved. The busy monitoring circuit for detecting the detection result and notifying the control result to the control means is arranged between the central office switch and the internal switch of the direct switching circuit. Therefore, unlike the prior art, it is possible to detect the talking state between the central office and the telephone in the normal state and the talking status between the central office and the telephone in the direct switching state with one busy monitoring circuit. Therefore, the number of parts of the direct line switching function-equipped central line trunk circuit can be reduced, and further miniaturization and high-density mounting can be further advanced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an office line trunk circuit with a direct switching function showing an embodiment of the present invention.

FIG. 2 is a circuit diagram (No. 1) for explaining a conventional direct communication switching circuit.

FIG. 3 is a circuit diagram (No. 2) for explaining a conventional direct communication switching circuit.

FIG. 4 is a circuit diagram showing a direct communication switching circuit in FIG. 2 or FIG.

FIG. 5 is a circuit diagram showing a direct communication switching circuit with a busy monitoring function.

FIG. 6 is a circuit diagram showing an internal structure of the office line trunk circuit shown in FIG. 2 or FIG. 3;

[Explanation of symbols]

 3 Subscriber circuit 4 Telephone 5 Central office switch 40 Station line trunk circuit with direct switching function 50 Station line trunk circuit 60 Direct circuit switching circuit 61 Switch section 62 Control circuit 63 Switching signal input circuit 64 Voltage monitoring circuit 65 Busy monitoring circuit

Claims (1)

[Claims] 1. A central line with a direct switching function, which is formed by incorporating a direct switching circuit for opening a direct call between a central office switch and a telephone by switching an internal switch in the same package and serving as an interface of a private branch exchange to the central office. In the trunk circuit, a busy monitoring circuit that monitors the line to detect the call status between the central office and the telephone, and notifies the detection result to the control means that controls the switching of the internal switch of the direct switching circuit, A central line trunk circuit with a direct switching function, which is arranged between the central office switch and the internal switch.