Patent GB-1195733-A (GB)
Title: Improvements in Electromagnetic Logic Elements Without Mechanical Moving Parts
Inventor: PESLIER JACQUES
IPC: H03K19/16
Filed: 1967-06-26
Abstract: 1,195,733. Non-contact-making relays. SOC. DE CONSTRUCTIONS ELECTROMECANIQUES JEUMONT-SCHNEIDER. 26 June, 1967 [6 July, 1966; 28 Oct., 1966], No. 29296/67. Heading H3B. A non-contact-making relay or logic device comprises a transformer core T, having primary and secondary windings, disposed in but not filling an air gap of a magnetic core structure M having at least one input winding a. The presence or absence of an input D.C. signal U c  to winding a prevents or permits coupling between the primary and secondary windings of the transformer, due to saturation or non-saturation of the core. Core structure M may be provided with additional limbs carrying further control windings, the winding senses being determined by the logical function to be performed. One of the limbs may be a permanent magnet carrying no input windings. These arrangements produce an output in load S in the absence of inputs sufficient to saturate the transformer core. In the arrangement shown in Fig. 4 an additional core structure including a permanent magnet is provided, there being air gaps between this structure and both the transformer core and core structure M. In this arrangement the transformer core is saturated by the permanent magnet in the absence of an input U c . The flux generated by an input opposes the permanent flux to remove the core T from saturation. In the self-holding arrangement shown in Fig. 5 the permanent magnet is enclosed by the transformer core T. Structure M has input windings a, a bias winding c and a feedback winding d. Application of an input U c  causes an output to be generated energizing winding d to maintain the state ofthe core after U c  is removed. The relay is released by interrupting the bias current. A device having complementary outputs (Fig. 6, not shown) includes a first arrangement similar to that shown in Fig. 1 and a second of the type shown in Fig. 4. The input windings are connected in series and the rectified output from the first device is supplied as feedback to the second device in opposition to the input. The switching of current from one load to the other takes place without overlap. A capacitor may be connected across the feedback winding, or the core may be provided with a short-circuited turn, to delay switching. A longer delay may be obtained using the circuit shown in Fig. 7. Capacitor C1 charges through resistor R1 until it is capable of firing unijunction transistor UJ which in turn fires thyristor Th. Capacitor C2, which has meanwhile been charged through resistor R2, now discharges through winding a to operate the self-holding relay arrangement. The relay is released by interrupting the transformer primary or secondary circuit. The Specification explains how the rate of switching may be increased by the provision of a feedback winding. The speed of operation of the device shown in Fig. 1 may be increased by providing a permanent magnet producing a flux insufficient to prevent an output being produced in the absence of an input. In the absence of an input the small output produced acts through a feedback winding to produce a flux in opposition to the permanent flux in the transformer core. As a result the output rapidly increases to its maximum value. The application of an input produces a flux aiding the permanent flux and tending to reduce the output current. The use of high remanence material for structure M enables the device to retain the state in which it was placed after removal of the input or interruption of the A.C. supply. A further winding must then be provided to cancel out the stored magnetization before application of a further input.