JPS5929036B2 - semiconductor communication path switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a communication path switch (generally referred to as a communication path switch or a channel switch) used mainly for a communication path in a telephone exchange or the like.

The following description will refer to a communication path switch. ) is related to semiconductorization. [Background of the Invention] There have been attempts to use semiconductor communication path switches in exchanges, but most of these have been methods using PNPN switches (called thyristors, SCRs, etc.).

A PNPN switch has a relatively low impedance when conducting, and a large insulation resistance when cutting off. Moreover, once turned on by a small gate signal, it has a self-holding action that continues to conduct unless the current is cut off externally. It is a useful element for implementing electronic communication channels in switching equipment. However, in telephone exchanges, the ringing signal (bell signal) of the telephone is a high-voltage alternating current, so current must flow in both positive and negative directions. It is common practice to turn on and off the circuit current, and the communication path switch must remain closed at this time as well. For this reason, the self-maintaining effect of the PNPN switch cannot be fully utilized for this type of application, and conventionally, dialing, ringing signals, etc. are processed separately.
A PNPN switch extracts only the call signal (small signal) superimposed on the DC current. [Object of the Invention] The present invention improves these drawbacks and provides a semiconductor switch that can directly process dialing, hooking, calling signals, etc. by combining a plurality of circuit elements. With the goal.

[Summary of the invention]

The present invention provides a gate-controlled bidirectional conductive semiconductor switch device having a pair of main terminals and a gate terminal connected to a communication path, and a high impedance 0N, 0FF controllable device connected to the gate terminal of this switch device. The present invention is characterized in that it is composed of a gate current circuit consisting of a constant current circuit having a backflow prevention means, a memory circuit that maintains this gate current circuit in an ON/OFF state, and a control circuit that controls this memory circuit.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor switch according to the present invention will be described in detail below with reference to FIGS. 1 to 3.

FIG. 1 shows a first embodiment of a semiconductor switch according to the present invention, and shows the basic unit of the structure. The gate-controlled bidirectional PNPN switch 1 connects the main terminal T1 to the communication path
1, the main terminal T2 is connected to the communication path Yj, and is arranged in a matrix grid with other bidirectional PNPN switches (not shown). Gate terminal G of switch 1 is reverse current prevention diode 2
After that, the AC high impedance gate current circuit 3
It is connected to the. Note that the diode 2 may be omitted if the gate current circuit 3 itself has a configuration in which no reverse current flows. The gate current circuit 3 is controlled by a memory 4, and the memory 4 is configured to be set and reset by an intersection selection circuit 5. In the embodiment shown in FIG. 1, a flip-flop is used for the memory 4, and the selection circuit 5 uses a method of setting and resetting the memory 4 by logical product of selection paths Xi, yj or Xi, yj. . Then, when signals arrive at the selection paths Xi and yj simultaneously, the memory 4 is set, whereby the gate current continuously flows from the gate current circuit 3 and the switch 1 is turned on. If the memory 4 is reset by the AND of the selection paths Xi and yj, the gate current circuit 3 will stop supplying gate current, or the switch 1 will have a self-holding function, so it is necessary to shut off the switch 1 externally. There is. However, in general, when a call ends, the call current is cut off by the telephone's switch, so no special control is required. These configurations generally use two bidirectional communication lines as balanced transmission lines and are assembled into an MXn lattice. An example of this MXn grating is shown in FIG. 3, and details will be explained in FIG. Now, regarding the individual elements of the configuration shown in Figure 1,
Add further explanation.

A gate-controlled bidirectional PNPN switch is a PN switch that has a control gate terminal and allows current to flow in either the positive or negative direction.
This refers to a PN switch, such as a switch called a triack.

However, as will be described later, a similar function can be obtained by connecting ordinary PNPN switches in antiparallel. The reason for choosing a PNPN switch is that, as mentioned earlier, in addition to the advantages of low conduction impedance and high insulation resistance, when used in the circuit of the present invention that also handles alternating current, it has a high withstand voltage in both positive and negative directions. This is because performance superior to transistors and other elements can be obtained, and, as will be described later, its self-holding effect can also be utilized depending on the potential distribution of the communication path. The reason why memory 4 is provided redundantly while providing a self-holding function to the switch is that even if the communication path current temporarily becomes zero due to passing AC or hooking dialing, etc., and switch 1 is turned off, the communication can be resumed. This is to keep the gate current circuit 3 in operation at all times so that current flows through the communication path immediately when voltage is applied to the communication path.

The reason why the gate current circuit 3 is made high impedance is as follows.
Since a constant gate control current can be supplied even if the potential between the switch and the control system fluctuates, stable control is possible regardless of the potential difference between the two, and power consumption is also low. The purpose is to prevent the call signal from flowing through the gate terminal G and from crosstalking to other circuits, and the magnitude or fluctuation of the current value is sufficient to impress the switch. If so, it's not a problem.

As shown in this embodiment, the selection circuit 5 can be used to select a communication route, such as a method in which setting and resetting are performed using separate selection circuits, or a method in which resetting is performed naturally when selecting another intersection, as in the embodiment described later. Design appropriately according to the purpose of the switch.

Although the gate current circuit 3 and the memory 4 are provided for each intersection, a part of the selection circuit 5 may be provided in common to one communication path switch. In commercial AC circuits, bidirectional PN
A common method is to apply a pulsed gate current synchronized with alternating current to a PN switch.

However, bell signals, dialing, hooking, etc. are information that cannot be predicted whether or when synchronization will occur, and the method of continuously monitoring this and controlling gate pulses requires the control circuit itself to be complicated and is not effective. Not. When the memory 4 is set and the PNPN switch 1 is turned on, the potentials of the terminals Xi and yj may both become higher than the limit potential that the gate current circuit 3 can supply depending on the potential relationship.

(In this state, a high positive power supply is applied to terminal Xi in Fig. 1, and terminal Y
It is sufficient to assume that a load resistance is connected to j. ) In this case, the conduction state between terminals Xi and yj is maintained only by the self-holding action of switch 1, and even though the gate current circuit 3 is trying to supply it, the gate current is actually It is conceivable that the current would be zero, and that if the diode 2 were not present, the current would flow backwards. However, for some reason P
As soon as the NPN switch 1 is turned off, the gate current can flow. Therefore, in the present invention, the meaning of continuously flowing a gate current includes a state in which the gate current does not substantially flow but is acting to flow. FIG. 2 shows a second embodiment of the semiconductor switch according to the present invention, and shows its basic unit, and similarly to the explanation of FIG. 1, it shows a part of one intersection of the communication path switch. There is.

In FIG. 2, ordinary gate-controlled PNPN switches 11 and 12 are connected in antiparallel to obtain a bidirectional PNPN switch. And a backflow prevention diode 21,
22 is provided at the gate terminal of each PNPN switch 11,12. The gate current circuit 3 is similar to that shown in FIG. 1, but the memory 4 and selection circuit 5 of FIG. 1 are integrated as a set priority flip-flop circuit 6. In such a configuration, when signals are applied to the selected roads Xi and xj at the same time, the set state is reached, and when a signal is applied to the selected road Yj to control another intersection, the selected road is reset.

This configuration does not increase the number of selection paths, and is an effective means for semiconductor communication path switches in electronic exchanges. These are assembled into a grid. FIG. 3 is a diagram showing an outline of a communication path switch configured in a balanced 2×2 grid using the semiconductor switch of the present invention. In order to avoid complication of the diagram, the intersection selection circuit etc. are not shown. Ta.

As illustrated in this figure, the call path switch is generally m×
It is made as an n-lattice, and has two bidirectional lines (A line, B line,
) is often constructed as a balanced transmission line. Note that a balanced transmission line is a circuit whose impedance to the ground is balanced, and is a circuit that transmits signals with two lines floating above the ground. Now, in the embodiment shown in FIG. 3, one memory M may be provided at the intersection, but since the potentials of the A line and B line are different, gate current circuits must be provided independently for the A line and the B line. is desirable.

In the above explanation, the circuit diagram has been shown assuming that the PNPN switch is turned on by flowing current into the gate, but if it is convenient to turn on by drawing current from the gate, the gate current circuit , the direction of the diode, etc. may be reversed.

Furthermore, it goes without saying that even if these circuit elements are not all assembled as an integral part, the circuit elements may be connected by wires or the like to substantially complete the whole. [
[Effects of the Invention] As explained above in detail, the semiconductor switch according to the present invention, when used as a call path switch of an exchange, can generate ringing signals,
Processing such as dialing and hooking can be handled in the same manner as a conventional mechanical communication path switch, and it will significantly contribute to the use of semiconductor switching equipment.

[Brief explanation of drawings]

FIG. 1 is a basic unit configuration diagram of a first embodiment of a semiconductor switch according to the present invention, FIG. 2 is a basic unit configuration diagram of a second embodiment of the present invention, and FIG. 3 is a basic unit configuration diagram of a semiconductor switch according to the present invention. A schematic diagram of a communication path switch configured as a 2×2 balanced type switch using the following is shown. 1...Gate-controlled bidirectional PNPN switch, 2゜゜゜゜゜゜゜backflow prevention diode, 3...
Gate current circuit, 4... Memory, 5...
- Intersection selection circuit, 6... Intersection selection/memory circuit, 11, 12... Gate control type PNPN switch, 21, 22... Backflow prevention diode.

Claims (1)

[Scope of Claims] 1. A gate-controlled bidirectional conductive semiconductor switching element having a pair of main terminals and a gate terminal connected to a communication path, a high impedance ON connected to the gate terminal of this switching element, It is composed of a gate current circuit consisting of a constant current circuit that can be turned off and has a backflow prevention means, a memory circuit that keeps this gate current circuit in an ON/OFF state, and a control circuit that controls this memory circuit. Characteristic semiconductor switch. 2. Assemble two bidirectional communication lines (A line and B line) into a column and row lattice as a balanced transmission line, and connect between the column A line and the horizontal line A, and between the column B line and the horizontal line B at each grid intersection. Gate-controlled bidirectional conductive semiconductor switching elements each having one gate terminal are arranged, and the gate terminal of each switching element is a constant current circuit that can perform high impedance ON/OFF control and has backflow prevention means. One current circuit each
One memory circuit is connected in common to each of the two gate current circuits connected to a pair of switch elements placed at each grid intersection, and one memory circuit is connected to each of the gate current circuits to keep the gate current circuits in the ON and OFF states. and turns this memory circuit ON and OFF.
A semiconductor switch characterized in that communication channels at each of the grid intersections are opened and closed by F control.