JPS6259500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a network control device that can preferentially use telephones.

When data communication is carried out using a general subscriber telephone line, the data terminal equipment usually does not have the function to control the exchange network, so network control (startup/recovery of the central office exchange, transmission of selection signals, etc.) is required separately. Requires equipment to perform. A network control unit (hereinafter referred to as NCU) has this function.

By the way, in this type of NCU, the telephone connected for calls and the data terminal device connected for data communication are often handled by the same operator, so these communication devices may conflict with each other. I didn't remember any particular situations in which it was used. In other words, with conventional NCUs, when a data terminal device occupies the telephone line and you want to make a call using the attached telephone, it is not enough to simply take the telephone off-hook; you must manually switch the telephone line from the data terminal device to the telephone. The need arose. Therefore, switching the telephone line becomes complicated, especially when a third party who is not directly involved with the data terminal equipment
Even if an attempt was made to use a telephone attached to a mobile phone, it was difficult to do so because the handling of the telephone was different from that of a regular telephone.

The present invention has been made in view of the above-mentioned circumstances, and even if the telephone line is connected to a data terminal device, if the telephone goes off-hook, the telephone line is automatically connected to the telephone, and a call is made with priority. The purpose is to provide a network control device that can

According to the invention, a first off-hook detector provides an off-hook of the telephone set when the subscriber telephone line is switched to a terminal device; and two off-hook detectors, and when the off-hook of the telephone is detected by the first and second off-hook detectors, the telephone line is given priority and connected to the telephone.

The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a network control unit (NCU), a telephone for telephone calls, and a data terminal device for data communication connected to the network control unit (NCU) according to the present invention. The NCU 100 has a pair of connection terminals 101, 1
02 to the subscriber telephone lines 400a, 400b, and to the telephone 200 via another pair of connection terminals 103, 104, and a connection terminal 105 for AC signal input/output, and a connection terminal 105 for dial information and control information. It is connected to the data terminal device 300 via the connection terminal 106.

This NCU 100 includes a first off-hook detector 110 and a second off-hook detector 120 that detect off-hook of the telephone 200, and high voltage noise input from subscriber telephone lines 400a and 400b or high voltage noise generated during dialing. a protection circuit 130 for shutting off, an automatic dialing unit 140 that generates a dial pulse based on dial information sent from the data terminal device 300;
It consists of a delay circuit 150 for switching the telephone line after a predetermined time delay from the off-hook time, a monostable multivibrator 160 driven by the first off-hook detector 110, and other circuits.

First, the operation of NCU 100 in the case where telephone 200 is not taken off-hook will be described using FIG. 2. When the telephone 200 is in the on-hook state, no current flows through the light emitting diode (LED) of the photocoupler 113 of the first off-hook detector 110, and the light receiving side is in the off state, so that the output signal F of the first off-hook detector 110 is is kept at "1" by an internal pull-up resistor (not shown) of the monostable multivibrator 160, and the output signal G of the monostable multivibrator 160 is also kept at "1". Also, in this state, the photocoupler 1 of the second off-hook detector 120
Since no current flows through the LEDs 21 and 122 and the light receiving side is off, the output signal H of the second off-hook detector 120 is set to "1" by an internal pull-up resistor (not shown) of the automatic dial section 140. is maintained. Therefore, the two inputs of the three-input AND circuit 161 are kept at "1" in this state.

Now, in this state, when the data terminal device 300 becomes the calling party and starts data communication, the data terminal device 300 first switches and connects the subscriber telephone lines 400a and 400b from the telephone 200 to the data terminal device 300 before starting the communication. information is sent to the automatic dialing unit 140 via the connection terminal 106. The connection terminal 106 is, for example, CCITT, V2
This applies to the 4,200 series interface. When the automatic dial section 140 receives the above information, it changes the signal A (FIG. 2a) supplied to the other input terminal of the AND circuit 161 from "0" to "1". As a result, the AND circuit 16
The signal appearing at the output terminal of 1 changes from “0” to “1”
and the signal B appearing at the output terminal of the OR circuit 163 with one input terminal connected to this output terminal.
(FIG. 2b) similarly changes to "1". A first relay 164 is connected to the output terminal of the OR circuit 163, thereby operating a first relay contact (flake contact) 164a. As a result, telephone 200 is disconnected from subscriber telephone lines 400a and 400b.

On the other hand, the output terminal of the AND circuit 161 is connected to the input terminal of the delay circuit 150 whose output side is connected to the other input terminal of the OR circuit 163, and the input terminal of the two-input AND circuit 1.
It is also connected to one input terminal of 62. The other input terminal of the AND circuit 162 is supplied with the signal C (FIG. 2 c) from the automatic dial section 140, but this signal C is outside the dial pulse generation period (T ₃ period shown in FIG. 2). So it stays at “1”. Therefore, when the first relay 164 is energized, the signal D appearing at the output terminal of the AND circuit 162
(Fig. 2 d) also changes to "1". AND circuit 1
A second relay 165 is connected to the output terminal of 62, thereby operating a second relay contact (make contact) 165a. As a result, transformer 16
6 through the subscriber telephone line 400a, 400
A loop current flows through b, forming a loop (section T ₂ shown in Figure 2). In addition, subscriber telephone line 400
The voltage E between a and 400b (Fig. 2e) is held at -48V during standby, but when the loop is formed, it becomes _V1 due to the voltage drop on the line.

The automatic dialing section 140 is a data terminal device 300
When the reception of the information for connecting the subscriber telephone lines 400a and 400b is completed, the signal C is changed according to the dial information (section _T3 shown in FIG. 2). As a result, the second relay contact 165a operates intermittently, and the subscriber telephone lines 400a, 400b
intermittent loop current. This becomes the dial pulse. After the transmission of dial pulses is completed and after a predetermined period of time (section _T4 shown in FIG. 2), the central device (not shown) and the data terminal device 300 are connected via the exchange, and the subscriber telephone lines 400a, 40
Data communication is performed by reversing the polarity between 0b and 0b (section _T5 shown in FIG. 2).

When the data communication ends, the data terminal device 300
sends information to that effect to the automatic dial section 140 via the connection terminal 106. As a result, the signal A is restored to "0" and the signal D changes to "0" as a result. When the signal D becomes “0”, the second relay 165
returns and the loop current is cut off. As a result, the exchange will be restored after a certain period of time (as shown in Figure 2).
T ₆ sections).

On the other hand, signal A becomes “0” due to the end of data communication.
Even if the switch is restored, the presence of the delay circuit 150 causes the signal supplied to the OR circuit 163 to remain at "1" for a predetermined time sufficient for the exchange to restore, and then change to "0". Therefore, after the exchange is restored and the polarity of the subscriber telephone lines 400a, 400b becomes -48V, which is the standby state, the first relay 164 is restored, and the telephone 200 is connected to the subscriber telephone lines 400a, 400b.
400b. (T ₇ section shown in Figure 2). In this case, before the telephone 200 is disconnected, the bell circuit capacitor inside the telephone 200 and the capacitor 112 of the first off-hook detector 110 are charged, so that the telephone 200
Since the voltage (-48V) between the terminals of 0 and the voltage (-48V) of the connected subscriber telephone lines 400a and 400b are equal, the bell will not ring even for a moment when the first relay 164 returns.

Next, a case where telephone 200 is taken off-hook while data terminal device 300 is communicating will be described with reference to FIG. As described above, during data communication in the on-hook state of telephone 200, "1" is supplied to each of the three input terminals of AND circuit 161. Therefore, both relays 164 and 165 are energized,
Relay contact (break contact) 164a turns off,
Relay contact (make contact) 165a is on. When the telephone 200 is taken off-hook in this state, the electric charge previously charged in the capacitor 112 while the relay contact 164a is on is transferred to the resistor 111, the telephone circuit, and the photocoupler 113.
Discharged through the LED. This discharge current makes the light receiving side of the photocoupler 113, one end of which is grounded, conductive, and the signal F changes to "0". When the discharge of the capacitor 112 is completed, the signal F returns to "1" (FIG. 3f). This change in signal F activates the monostable multivibrator 160, and its output signal G (Fig. 3g) remains at " ₀ " for a predetermined time T8.
It holds the state and then returns to "1". This time T ₈ is set to be slightly longer than the delay time T ₉ of the delay circuit 150. Automatic dialing section 140 detects off-hook of telephone 200 from the change in output signal G, and notifies data terminal device 300 of the off-hook via connection terminal 106. Data terminal device 300 thereby terminates data communication.

On the other hand, at the stage when the signal G changes to "0", the signal appearing at the output terminal of the AND circuit 161 also changes to "0", and the second relay 165 returns to its original state. As a result, the loop current is cut off and the exchange is restored after a certain period of time _T10 has elapsed. The first relay 164 is reset by the delay circuit 150 after the recovery operation of the exchange is completed. Therefore, at the stage when the first relay contact 164a is restored, the exchange detects the call again due to the loop current flowing through the telephone, and
While transmitting a dial tone signal, the telephone 2
A dial pulse of 00 can be accepted.

During a call using the telephone 200, current flows through either of the two photocouplers 121, 122 connected in opposite directions in the second off-hook detector 120. Therefore, the signal H is always "0" until the call ends, and data communication by the data terminal device 300 can be prohibited.

As explained above, according to the present invention, even if the telephone line is connected to a data terminal device, if the telephone goes off-hook, the telephone line is automatically connected to the telephone. There is no need to switch manually, and the handling of the telephone is exactly the same as a normal telephone, so even a third party not directly involved with the data terminal device can use the telephone attached to this NCU. In other words, according to the NCU according to the present invention, it is possible to perform data communication using the idle time of the telephone without giving particular consideration to the telephone user. Furthermore, it is possible to prevent the telephone from ringing when switching to and returning from data communication.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a network control device according to the present invention connected to a telephone and a data terminal device, and FIG. 2 is a signal waveform diagram of each part to explain the operation of the NCU when the telephone is on-hook. , FIG. 3 is a signal waveform diagram of each part for explaining the operation of the NCU when the telephone is taken off-hook during data communication. 100... Network control unit (NCU), 110... First off-hook detector, 120... Second off-hook detector, 130... Protection circuit, 140... Automatic dial section, 150... Delay circuit, 160 ……
Monostable multivibrator, 164...first relay, 164a...first relay contact, 165...
...second relay, 165a...second relay contact, 200...telephone, 300...data terminal device, 400a, 400b...subscription telephone line.

Claims (1)

[Scope of Claims] 1. Switching means for switching a subscriber telephone line from a telephone to a terminal device during data communication; and a first off-hook detection unit for detecting an off-hook of the telephone when the subscriber telephone line is switched to the terminal device. a second off-hook detector for detecting off-hook of the telephone when the subscriber telephone line is switched to the telephone; and said switching means when off-hook of the telephone is detected by the first off-hook detector. control means for switching to the telephone side after opening the subscriber telephone line for a predetermined period of time, and prohibiting data communication while off-hook of the telephone is detected by the second off-hook detector. Control device. 2. The first off-hook detector consists of a circuit in which a series circuit consisting of a resistor, a capacitor, and a light-emitting diode of a photocoupler is connected in parallel to the telephone, and a diode is connected in parallel to the light-emitting diode with opposite polarity. 2. The network control device according to claim 1, wherein off-hook of the telephone is detected by detecting a discharge current discharged from the capacitor by the photocoupler when the telephone is off-hook.