GB1155616A - Improvements to Reed Relay Switching Networks - Google Patents

Abstract

1,155,616. Automatic exchange systems. M. ROUZIER and H. MARNAT. 8 July, 1966 [17 July, 1965], No. 30876/66. Heading H4K. Cross points in a reed-relay matrix, such as 101, are controlled by a control wire 21 11 in each row and two control wires in each column (the column control wire 11 11 being shown but the auxiliary column control wire being a coinmoning of diodes such as 31 111 ), an auxiliary reed contact 1 111 and a winding 32 111 being connected in series between the control wires 21 11 and 11 11 while the junction between the winding and the auxiliary contact is connected over the diode 31 111 to the auxiliary column control wire. A row of the matrix 101 is selected by a decoder 44 which causes transistor 41 to conduct to replace earth with - 12 volts on the row control wire. A column of the matrix 101 is selected by decoder 45 1 which causes transistor 42 1 to conduct to replace - 12 volts with earth on the auxiliary column control wire. Current in the winding 32 111 operates the reed contacts 1 111 , 2 111 , 3 111 , the auxiliary contacts 1 111 connecting the junction 33 111 to the column control wire 11 11 by way of which the winding is eventually supplied with holding current from + 12 volts to earth over normally conducting transistor 43. To set up a connection from a channel A, which is a row of matrix 101, to a channel B, which is a column of matrix 103, by way of a cross-point in matrix 102, the decoders 44 and 45 1 operate an appropriate crosspoint in 101 as described above. While the pulse from decoder 45 1 still persists, a decoder 45 2 selects an appropriate column in matrix 102 and energizes the winding 32 112 in series with the energized winding 32 111 of matrix 101. When the cross-point in matrix 102 is fully energized the pulse from decoder 45 1 ceases and a pulse is produced by decoder 45 3 to connect the required outlet in matrix 103 by energizing the winding 32 113 . When the contacts of the cross-point in matrix 103 are made the pulse from decoder 45 2 ceases. The pulses from decoders 44 and 45 3 now cease and the windings 32 111 , 3 112 and 32 113 are held in series with their auxiliary contacts 1 111 1 112 and 1 113 between earth over the normally conducting transistor 43 and + 12 volts over a resistor 40 connected to the control column wire of channel B. To release the connection a decoder 46 identifying the channel A cuts off transistor 43 to replace earth by + 12 volts on the row control wire 22 11 . To damp transients produced in the control windings on disconnection of the hold circuit, diodes provide a closed loop to the reverse voltages generated. Before the hold contacts of each cross-point coil open the diode 49 and resistor 40 provide the loop, when the hold contacts open a loop continues to be provided through the battery and diodes 31 and 48 and diodes 49 or 61 depending on the stage of the cross-point. The selection of free links between the matrices, and the selection of free outlet channels B, is made by sensing magnetic cores 81 11 , 82 12 , 88 13 associated with the matrix column control wires. Interrogation of the cores will indicate which columns are engaged due to holding current in the control wires. Identification of the inlet channel A connected to a particular channel B can be made on instruction from a decoder 70 by momentarily short circuiting resistor 40 to cause a current surge over the holding circuit, a magnetic core 91 11 associated with the control wire of the channel A being turned over by the surge to provide the required identification. The reverse process of identification, finding the channel B connected to known channel A, is effected by decoder 44 which switches on transistor 41 to cause a surge in holding current which appears over resistor 40 to be identified by an encoder 71.