JPS62276949A - Network control unit - Google Patents

Abstract

PURPOSE:To improve a talking by providing an off-hook detection section in a network control unit and applying the control so that the DC impedance of the network control unit side viewed from a communication line is equal to the DC impedance at off-hook of a telephone set. CONSTITUTION:A network control unit l is provided with an off-hook detection section 3, changeover switches 4, 5 and a control section 7 switching the change over switches 4, 5 by a signal from the off-hook detection section 3 and a struc ture switching automatically the connection circuit of a communication line 12 and a telephone set 11 is adopted. The DC impedance of the network control unit 1 viewed from the line 12 is made equal to the DC impedance at off-hook of the telephone set. Thus, no level reduction at talking is caused.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to a network control device.

[Prior Art] A network control device connects a communication line and a telephone, and has an automatic call receiving function.

When this network control device forms a DC loop for a communication line, the provider of the communication line is required and recommended to ensure that the DC impedance seen from the communication line side is equal to or less than a predetermined value RS.

On the other hand, the components of the DC impedance include the DC impedance RT when the telephone is off-hook, and the DC impedance RN from the line connection terminal of the network control device to the telephone connection terminal.

The DC impedance R~ is an impedance generated due to the automatic call receiving circuit.

Therefore, unless R3<RT+R~, a drop in the level of transmission and reception will occur during communication via the telephone, so currently efforts are being made to satisfy the above-mentioned DC impedance condition.

[Problems to be solved by the invention] However, the computerized telephones that have been widely used recently have a DC impedance RT when the telephone is off-hook.
This has the disadvantage that the RT is larger than that of conventional telephones, and the above-mentioned problems are likely to occur.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention includes an off-hook detection means for detecting an off-hook state of a telephone in a network control device that connects a communication line and a telephone, and a communication A changeover switch that changes the connection state between the line and the telephone set, and a control unit that changes over the changeover switch according to a signal from an off-hook detection means, and the DC impedance on the network control device side as seen from the communication line is the DC impedance when the telephone set is off-hook. We have adopted a structure that allows control to occur in minutes.

[Function] When the above-described structure is adopted, the DC impedance on the network control device side can be set to a value below a predetermined value that does not cause a drop in the level of transmission and reception, making it possible to make good calls.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

The figure explains one embodiment of the present invention, and illustrates a case where the present invention is applied to a facsimile machine.

In the figure, reference numeral 1 indicates the entire network control device, and the telephone 11
and a communication line 12, respectively.

A call signal detection section 2 is provided within the network control device 1, and is connected to the communication line 12 side via a changeover switch 4 for selecting a connection route.

The changeover switch 4 has the role of selecting a connection route between the telephone set 11 and the communication line 12.

Further, the calling signal detection section 2 is connected to an off-hook detection section 3, and the off-hook detection section 3 is connected to a telephone set 11 or a modem section 6 via a changeover switch 5.

The changeover switch 5 is a changeover switch for connecting the communication line 12 to the telephone set 11 or the modem unit 6.

On the other hand, the reference numeral 7 is a control section for controlling all operations, and constantly monitors the call signal detection section 2 and the off-hook detection section 3, and controls the changeover switch 5.

An operation display section 8, a reading section 9, and a recording section 10 are connected to the control section 7, and the modem section 6 is also under control.

Note that the sum of the internal DC impedances of the ringing signal detection unit 2 and the off-hook detection unit 3 is RN, and the DC impedance of the telephone 11 when off-hook is RT, and RN
<R3, RT <Rs.

And, except during facsimile communication, selector switch 5
is connected to the C terminal, that is, to the telephone l111 side.

Next, the operation of this embodiment configured as above will be explained with reference to the flowchart of FIG. 2.

The control unit 7 monitors whether the device is in a standby state, an off-hook state, an automatic reception mode, or a manual reception mode, as shown in steps St to S4 in FIG. .

When the standby state is detected in step S1, the selector switch 4 is kept connected to the a terminal in step S5.

If it is not in the standby state, the operation has started, so it is detected in step S2 whether or not an off-hook has been performed, and if it is off-hook, the selector switch 4 is connected to the b terminal in step S6. .

If it is determined that off-hook is not performed, it is determined in step S3 whether or not the automatic reception mode is set;
In the case of automatic reception mode, the calling signal detection section 2 detects this, connects the changeover switch 5 to the d terminal (step S7), and transmits and receives signals via the modulation/demodulation section 6 to perform facsimile communication.

Since the DC impedance in this case is RN, it is smaller than Rs and there is no problem.

On the other hand, in step S4, it is determined whether or not the mode is the manual reception mode, and if the mode is the manual reception mode, the telephone 11 rings.

When the user takes off-hook the telephone 11 in response to this, the process returns to step S2, the off-hook detection section 3 detects the off-hook state, and the changeover switch 4 is turned on in step S6.
Since the terminal is connected to the b terminal, the user can make calls.

In this case, the DC impedance is only R, and R
It is smaller than 5 and there is no problem.

When the user returns the telephone 11 to the on-footer state, the off-hook detection unit 3 detects this, and the control unit determines that the telephone set 11 has returned to the standby state.

As described above, the DC impedance on the network control device side seen from the line side can be suppressed to below the predetermined value RS,
There is no drop in the level of transmission and reception, and there is no problem with communication.

In the above-described embodiment, a facsimile machine was used as an example, but the present invention can be similarly applied to any communication device having a network control device that connects a communication line and a telephone.

In addition, recently, some telephones are equipped with a function to output a signal indicating an off-hook state. Part 3 becomes unnecessary.

Furthermore, when the automatic reception mode is set, selector switch 4 is connected to the b terminal in standby mode, and selector switch 4 is connected only when performing facsimile communication.
It is also possible to connect 5 to the a terminal and 5 to the d terminal, respectively.

[Effects] As is clear from the above description, according to the present invention, an off-hook detection means is provided in the network control device, and a structure is adopted in which the connection circuit between the communication line and the telephone is automatically switched. The DC impedance on the network control device side seen from the line can be reduced to just the DC impedance when the phone is off-hook, so there is no level drop during a call.
Good calls are possible.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention, and FIG. 1 is a block diagram of a control circuit, and FIG. 2 is a flowchart of the control operation. 1... Network control device 2... Call signal detection section 3... Off-hook detection section 4.5... Changeover switch

Claims (1)

[Claims] A network control device that connects the communication line and the telephone includes an off-hook detection means for detecting an off-hook state of the telephone, a changeover switch for switching the connection state between the communication line and the telephone, and a signal from the offhook detection means to switch the changeover switch. What is claimed is: 1. A network control device, comprising: a controller, and controls the DC impedance of the network control device side as viewed from a communication line to be equal to the DC impedance of the telephone when the telephone is off-hook.