JPH0290797A - Push-button telephone main device - Google Patents

Abstract

PURPOSE:To make the user of an extension telephone set select another telephone line in nonuse before performing dial outgoing by displaying infeasibility to connect a line to a selected telephone line on the display part of the extension telephone set by detecting a DC current after closing the line. CONSTITUTION:In the case of performing outgoing by the extension telephone set 2, a control circuit 13 starts up a line closing circuit 12, and closes the telephone line 3 by a control signal from the extension telephone set 2. At this time, the control circuit 13 continues the closure of the line when a DC current detection circuit 11 detects the current exceeding value set in advance, and opens the line of the line closing circuit 12 when no current exceeding the value set in advance is detected, and displays that the telephone line 3 has already been used on the display device of the extension telephone set 2. In such a way, it is possible to recognize that the telephone line 3 is being used by the user of the telephone set 2, which eliminates invalid dial outgoing.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a button telephone main device.

[Conventional technology]

Conventionally, this type of key telephone main device was configured to connect the telephone line to the selected extension telephone without measuring the DC current value after the line was closed, even if another device was connected to the telephone line. was.

[Invention or problem to be solved]

The conventional key telephone main device described above is not configured to measure the direct current value of the telephone line, so in addition to the key telephone device connected to the telephone line, for example, a facsimile device may be connected at a remote location. If the facsimile machine is using a telephone line, the operator cannot be notified via the extension telephone that the telephone line is unavailable, and the operator makes an invalid dial as a result. There is a drawback that there are cases.

[Means to solve the problem]

The key telephone main device of the present invention is a key telephone main device that accommodates at least a -line telephone line and a plurality of extension telephones each having a display section indicating the usage status of the telephone line, when the extension telephone goes off-hook. a line closing circuit that closes a telephone line; a direct current detection circuit that detects a direct current flowing from the telephone line to the line closing circuit when the line closing circuit is closed; a control unit that opens the line connection circuit when detecting a DC current value below a set value and sends a signal indicating that the telephone line is in use to a display unit of the extension telephone to display that the telephone line is in use; have.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, the key telephone main device 1 of this embodiment is -
It accommodates a telephone line 3 and an extension telephone 2 with a built-in display (not shown) indicating the usage status of this telephone line,
A line closing circuit 12 that closes the telephone line 3 inside, and a line closing circuit 12 from the telephone line 3 when the telephone line 3 is closed.
A DC current detection circuit 11 detects whether the flowing DC current is below a preset current value, and a line closing circuit 12 based on the detection signal from the DC current detection circuit 11.
a control circuit 13 which causes the telephone line 3 to be opened and the display of the extension telephone 2 to display that the telephone line 3 is in use;
It is composed of:

Next, the operation of this embodiment will be explained.

When the extension telephone 2 makes a call, the control circuit 13 activates the line closing circuit 12 to close the telephone line 3 in response to a control signal from the extension telephone 2. At this time, if the DC current detection circuit 11 detects a current exceeding a preset value, the control circuit 13 causes the line to continue to be connected, and when it cannot detect a current exceeding the preset value, the control circuit 13 closes the line. Connection circuit 1
2 is opened, and the display of extension telephone 2 indicates that telephone line 3 is already in use.

Claims (1)

[Claims] In a button telephone main device accommodating at least one telephone line and a plurality of extension telephones each having a display section indicating the usage status of the telephone line, a line closing function that closes the telephone line when the extension telephone goes off-hook. a direct current detection circuit that detects a direct current flowing from the telephone line to the line closing circuit when the line closing circuit is closed;
When this DC current detection circuit detects a DC current value below a preset value, it opens the line connection circuit and sends a signal to the display of the extension telephone indicating that the telephone line is in use. 1. A button telephone main device comprising: a control section for displaying the inside of the telephone;