GB1354770A - Magnetic devices - Google Patents

Abstract

1354770 Moving domain devices WESTERN ELECTRIC CO Inc 18 June 1971 [24 June 1970] 28778/71 Heading H3B In a moving magnetic domain device, Fig. 1, domains representing '0' and '1' bits are propagated in two distinct channels separated by a magnetically soft material or by a groove in the sheet containing the domains. The sheet 11 has two circulating paths defined by a loop of permalloy 12, and two serpentine conductors 14, 15 are provided on respective faces of the sheet to move domains such as D along the paths. The domains shown at D are assigned the bit '0', while those lying on the outer edge of the loop signify '1'; only the latter are detected by a reading device for supply to a utilization circuit 24, the absence of a '1' signifying a '0' in the usual manner. The domains are maintained stable in size by a bias field set up by source 25. Domains are not created and destroyed, but a '0' domain may be converted into a '1' by pulsing a loop conductor such as that shown at 20 in Fig. 2, to displace it across the permalloy loop 12; by reversing the current a '1' may be drawn across the loop to become a '0'. Such pulses are derived from source 21, Fig. 1, under control of synchronizing circuitry 26. The dimensions of the permalloy strip govern the ease with which domains are displaced across it, and the width is chosen to be about 0À7 times the domain diameter in regions where displacement across it may be desired. Elsewhere the width is 0À5 times the diameter except around the reading device where a factor of 0À2 is used to separate the '0' and '1' domains widely. The reading device may be a simple conductor loop or Hall probe, or optical reading by Faraday or Kerr effect may be used.