JPS61166272A - Network control circuit - Google Patents

Abstract

PURPOSE:To attain miniaturization of the circuit, to improve the economy and the reliability by providing the 1st, 2nd and 3rd semiconductor switch circuits controlling the connection to the circuit, acquisition of the line or transmission of a pulse dial and the connection between the line and a facsimile equipment in series with a rectifier circuit converting and holding the polarity state of the line to a constant value. CONSTITUTION:A resistor 215 in the 1st semiconductor switch circuit gives a DC voltage bias to a gate of an FET216 to the line and a telephone set 203, an incoming detection means 222 and the line are subject to connection control. Transistors 213, 214 in the 2nd semiconductor or acquire the line during communication and a resistor 227 decides the DC current acquiring the line. A capacitor 217 couples the line and a transmission/reception part of the facsimile main body 212 through a hybrid circuit with AC signal component only and an analog switch 218 of the 3rd semiconductor switch circuit applies input/output switching control to the AC signal to the line.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a network control circuit for connecting facsimile machines to a line.

Conventional technology Figure 2 is a block diagram showing a conventional network control circuit. Indicates that the machine is waiting for a facsimile call.

Facsimile cutter 111. It is connected to a subscriber telephone network or a facsimile communication network via a CML relay 104 and a relay 108 that generates pulse signals. This connection circuit includes subscriber telephone network incoming call detection means 1o6 in parallel.
．． The facsimile communication network incoming call detection means 107 and the photocoupler 102 are connected in series to a polarity reversal detection circuit 109.
is connected. A telephone set 112 is attached to the facsimile machine, and a disconnector 111 connects the connection circuit or subscriber telephone network incoming call detection means 1o6. It is connected so as to be switched to either the parallel circuit of the facsimile communication network incoming detection means 107 and the photocoupler 102.

CMI! A letter coil 106 is provided downstream of the relay 108 so that the line forms a DC circuit when the J series 04 is closed.

The subscriber telephone network incoming call detection means 106 includes a photocoupler 106a that receives an incoming call signal from the telephone network and this photocoupler 1.
It has a telephone detection circuit 106b which detects an incoming call based on the output signal of 06a.

The facsimile communication network incoming call detection means 107 is a high impedance transformer 107a that receives an incoming facsimile signal.
and a facsimile detection circuit 107b that detects incoming facsimile calls based on the output of the transformer 107a.

When an incoming call is detected by the subscriber telephone network incoming call detection means 1'06 or the facsimile communication network incoming call detection means 107, C
The ML relay 104 is closed, and the telephone set 112 subscriber telephone network incoming call detection means 106 and the facsimile communication network incoming call detection means 107 are disconnected from the line, and at the same time, the capacitors provided at both ends of the letter coil 106 disconnect the line and the facsimile. AC coupled. In the network control circuit having such a configuration, when on standby, the CML relay 104 is in an open state, and the lines are connected to the telephone set, subscriber telephone network incoming call detection means 106, and facsimile communication network incoming call detection means 107, respectively. However, the subscriber telephone network incoming call detection means 106
Or, when the facsimile communication network incoming call detection means 107 detects the incoming call from the network, the CML vC1
04 is closed, the telephone set, subscriber telephone network incoming call detection means 10
6 and the facsimile communication network incoming call detection means are disconnected from the line.

When the CML relay 104 is blocked, the letter coil 106 forms a DC circuit of the line, and AC coupling from both ends with capacitors converts the 2-wire 4M conversion into the hybrid coil 11.
It is connected to the facsimile machine via 0. In the case of automatic call origination, it is necessary to prevent collision with an incoming call, and for this purpose, the L relay 101 is closed and the photo coupler 10 is
After confirming that there is no polarity reversal of the line for a certain period of time using the output 103 of 2, the CML relay 104 is closed.
It is configured to turn on and off the P relay 108 depending on the number of the other party and transmit a pulse dial signal to the network. When all digits of the dial number have been sent, the polarity reversal detection circuit 109 confirms the other party's response, and the CML relay 1
Facsimile communication is performed with 04 closed and the line captured. Note that the switch is normally closed except during testing or maintenance inspection. The subscriber telephone network incoming call detection means 106 is coupled to the line by a photocoupler that is AC-coupled by a capacitor, and the facsimile communication network incoming call detection unit 107 is coupled to the line by a transformer that is AC-coupled to the capacitor. Both are being carried out.

Problems to be Solved by the Invention However, such conventional network control circuits have a CML relay for switching the signal path from the line, an L relay for preventing collisions between calls and calls, and a relay for dialing and pulse transmission. Because it has multiple relays such as P relays, letter coils and hybrid coils for connecting DC circuits of lines, and multiple coils such as coupling coils with high input impedance for connecting to the facsimile communication network incoming detection circuit, It has the unavoidable disadvantage of increasing its size.

In other words, to explain this in detail, in order to withstand the line's DC current of approximately 100 mA and DC voltage of approximately 48 V, as well as to prevent magnetic saturation and match impedance, the windings of the hybrid coil or letter coil must be made thicker. At the same time, the size of the magnetic material must also be increased, so it is actually difficult to downsize these hybrid coils and letter coils.

In addition, when connecting a two-wire balanced line to an unbalanced incoming call detection circuit, it is necessary to connect a subscriber telephone network with a high level of incoming signal (
For facsimile communication networks (1300Hz), where the incoming signal level is low, photocouplers cannot be used and transformer coupling must be used. CML for signal path switching! Regarding the J-ray, it was also impossible to downsize it from the viewpoint of the reliability of the contact and the economical efficiency of the contact material.

The present invention eliminates the disadvantages of the prior art as described above, and provides a letter coil for forming a DC circuit, an hybrid coil for 2-wire and 4-wire conversion, and a facsimile. The impedance characteristics seen from the line were improved by eliminating the contact coil between the incoming call detection circuit of the communication network and the line, and the various relays used to switch signal paths were also eliminated to reduce the size of the circuit. The purpose of the present invention is to provide a network control circuit that can improve network economy and achieve high reliability.

Means for Solving the Problems The present invention attempts to achieve the above object by using semiconductor switches as a means for switching signal paths and a means for forming a direct current circuit of lines in a network control circuit. .

Since the relay circuit for switching the signal path of the working line and the letter coil that forms the DC circuit are replaced with semiconductor switch circuits, the circuit can be made smaller and more reliable.

Embodiment Below, details of a network control circuit according to an embodiment of the present invention will be explained with reference to FIG. Reference numeral 210 is a slide switch for manually switching the line directly to the telephone set 203 during testing or maintenance inspection, and is normally in a closed state. 202
is a rectifier circuit composed of a diode bridge circuit, which converts to direct current while maintaining the polarity state of the line, whether it is earth or negative. In the present invention, for the output of the rectifier circuit 202, a first semiconductor switch circuit is constructed of a resistor 215 and a field effect transistor FET 216, and a resistor 227 and a pair of transistors 213 and 214 connected in Darlington. An analog switch 218 constituting a third switch circuit is connected via a second semiconductor switch, a circuit, and a capacitor 217. 204 and 206
2 is a resistor that shunts the direct current of the line and energizes the photocoupler 208; 206 is a varistor for overvoltage protection;
o7 is an AC signal bypass capacitor, and 209 is a constant voltage diode for overvoltage protection. Photo coupler 2
08 consists of a pair of light emitting diodes and a transistor connected in parallel in opposite directions to detect polarity reversal of the line. 210 is a transistor that controls a weak current that enables one of the light emitting diodes 9 of the 7 Oto couplers 208 to light up without seizing the line prior to automatic calling; 211 is a transistor that controls this current; It is the resistance that determines the value. Reference numeral 212 is a 7'7 comb main body, which controls on/off of the semiconductor switch circuit of the present invention based on a communication procedure.

Now, to explain the first to third semiconductor switch circuits of the present invention in more detail, the resistor 215 in the first semiconductor switch circuit applies a bias to the gate of the FET 216 with the DC voltage of the line, High voltage enhancement type MOS (metal oxide
(semiconductor) FET 216 is normally in the on state due to the resistor 216, but the telephone 203
and connects and controls the line with the incoming call detection means 222. Transistors 213 and 21 in the second semiconductor switch circuit
Reference numeral 4 is provided to capture the line during on/off operation or communication when pulse dialing signals are sent out, and the resistor 227 determines the DC current value for capturing this line. .

A capacitor 217 connects the line and the transmitter/receiver section of the facsimile main unit 212 via a hybrid circuit to AC signals 10, X-
This AC signal is coupled only by the No. 1 component, and an analog switch 218 forming a third semiconductor switch circuit controls input/output switching of this AC signal to/from the line. Note that this analog switch 218 is turned off except during communication.

219 is a buffer FET that realizes a high input impedance to guide the calling signal from the network to the incoming call detection means 222 without affecting the line, 220 is a resistor that determines this high input impedance, and 221 is an AC coupling resistor. It is a capacitor. The incoming signal detecting means 222 is constituted by a frequency or period integrating circuit that automatically discriminates between a 16 Hz bell ringing signal in the case of a subscriber telephone network or a 1300 H2 silent ringing signal in the case of a facsimile communication network. 223 is the input resistance 224 and 22 of FET 219
5 is a clamp diode for protecting the gate input of FET 219. 226 is a hybrid circuit that performs two-wire and four-wire conversion, and is coupled to the analog switch 218 with an input/output impedance of 600Ω.

11 Behr • Next, the operation of the network control circuit configured as described above will be explained. In the standby state, only FET 216 is on. During automatic dialing, FET21e is turned off and transistor 210 is turned on for about 300 milliseconds.During this time, if polarity reversal is detected by photocoupler 208, a call signal is sent, which turns off transistor 210 and turns on FET216. is turned on, and after the incoming call detection means 222 detects an incoming call, the FET 21 e is turned off, and the transistors 213 and 214 and the analog switch 218 are turned on, forming a DC circuit and transmitting an AC signal to the facsimile body 212 via the hybrid circuit 226. The facsimile machine becomes ready for communication. The operation of automatic reception from the standby state when there is no automatic call operation is performed in exactly the same manner as described above. If no polarity reversal is detected during the on-state of transistor 210 for about 300 milliseconds, a dial pulse is sent to the network by controlling on/off of transistors 213 and 214 with transistor 210 off.

When the transmission of dial pulses for all digits is completed, the photocoupler 208 is turned on with the transistors 213 and 214 turned on.
The connection response is confirmed by reversing the polarity, and the analog switch 218 is turned on to form a signal path for facsimile communication via the hybrid circuit 226.

Also, when performing tone dialing instead of pulse dialing, a dial tone is sent from the facsimile main body 212 via the analog switch 218 and the hybrid circuit 226 with transistors 213 and 214 turned on, and all digits are sent out. The operations after completion are the same as those for the pulse dial described above.

When the photocoupler 208 does not detect a polarity reversal as a connection response confirmation from the network at the end of dialing, or when an i interrupt instruction from the network is detected as a polarity reversal during facsimile communication, the facsimile machine enters the standby state. Return.

Although one embodiment of the present invention has been described above, the configuration of the half-13-page conductor switch circuit is not limited to the transistors shown in FIG. 2, but may be configured using any of four bipolar FET transistors or thyristors.

Effects of the Invention According to the present invention as detailed above, both the relay circuit for switching the signal path of the line and the letter coil forming the DC circuit, which were conventionally considered indispensable in the network control circuit, are made of semiconductors. Since it is replaced by a switch circuit, it has the effect of making the circuit smaller, more reliable, and more economical, and since the hybrid circuit is composed of a differential amplifier and a resistor, eliminating the need for relays and coils, it can be used as an integrated circuit. This has the effect of greatly improving the impedance frequency characteristics of facsimile communication signals seen from the line, and from this point of view as well, the reliability of communication can be improved.

FIG. 2 is a block diagram showing the schematic structure of a conventional network control four-vane circuit.

-201...Slide switch, 202...
... Rectifier circuit, 203 ... Telephone device, 216,
219...FET, 206...Barista, 20 Ou...7 Otocoupler, 209...
... Constant voltage diode, 218 ... Analog switch, 212 ... Facsimile body, 222
...Incoming call detection means, 223, 225...
・Klemp diode, 226...Hybrid circuit.

Claims (1)

[Claims] A rectifier circuit that converts and maintains the line polarity constant, a first semiconductor switch circuit that controls the connection with a circuit that detects a call signal from the network, and a DC circuit that forms a direct current circuit to capture the line or pulse dial. A second semiconductor switch circuit for controlling the transmission of the facsimile and a third semiconductor switch circuit for controlling the connection between the line and the facsimile machine are respectively provided in series. Network control circuit for connecting to the network.