Patent GB-883954-A (GB)
Title: Electric switching devices using magnetic particles
IPC: H03K17/82
Filed: 1958-03-03
Abstract: 883,954. Electromagnetic switches; magnetic switches. TANN CORPORATION. March 3, 1958 [March 6, 1957 (3); March 11, 1957], No. 6820/58. Class 38 (5). [Also in Group XXXIX] In a switch closed by the alignment of magnetic particles forming conducting paths, the particles are in a cavity between two grids comprising conducting magnetizable members separated and surrounded by non-magnetic material. In Fig. 1, the ends of the magnetizable members 13 of the grids 10, 12 are connected to conducting plates 15 in the load circuit. Insulating members 16 surround the cavities 17 and coils 19 surround the grids 10, 11, 12. The coils surrounding the grids 10, 12 are connected to a battery 24 so as to magnetize the respective elements 13 and energization of the coil 19 surrounding the grid 11 aligns the balls 18 to complete the load circuit. Alternatively the switch 26a may be replaced by a change-over switch (Fig. 2, not shown), the completion of the load circuit depending on current direction, or other (e.g. differential) circuit arrangements may be used. The elements 13 of the grids may be arranged in different forms and sizes and some may be permanent magnets with or without coils about their grids. A conductor may be connected to the elements 13 of the grid 11 to form a change-over switch or only two grids may be used for a simple switch. The balls 18 are of annealed magnetic material and may be coated in conducting material or may be used without coating or with a coating of high resistance so as to relate the current therethrough to the number of chains of balls which will depend on the magnitude of the magnetizing current. Numerous applications and forms of the device are described including cavities, partially filled with mercury and grids energized by a movable permanent magnet. In Fig. 13, ceramic permanent magnets 77 above the grid 78 are opposed by the flux of a coil 69 to break the chains of balls 67 either simultaneously or progressively to interrupt the circuit or reduce the current therein. In Fig. 16, operation of a change-over switch 93 effects the switching of two separate circuits 88, 89 dependent on the relationship of the flux in coils 92 of the flux of a permanent magnet 85. In Fig. 18 the current in a circuit 118 is made to fluctuate in accordance with the output of a control device 124 which causes variations in the number of chains of balls 117. In Fig. 26 the elements 162 in both grids are permanent magnets and a movable permanent magnet 171 neutralizes the magnetism of the upper elements 162 to form the chains of balls. In Fig. 30 the upper permanent elements 162 are surrounded by short-circuited coils which on current interruption produces flux to assist in demagnetizing the balls 167. In Fig. 38 (not shown), a single cavity device with only one coil acts as a half-wave rectifier and such a device (Fig. 41) may be provided with switching means to vibrate a band 254 secured to wool or like material 253 surrounding a rubber sleeve 252 about the cavity 251 so giving the balls static charges to repel each other on demagnetization.