Patent GB-962661-A (GB)
Title: Thin film memory apparatus
IPC: H01F10/00
Filed: 1960-10-25
Abstract: 962,661. Magnetic storage devices. KOKUSAI DENSHIN DENWA KABUSHIKI KAISHA. Oct. 25, 1960 [Oct. 26, 1959; Aug. 29, 1960], No. 36613/60. Heading H1T. [Also in Division H3] The co-ordinate conductors of a magnetic storage matrix are sandwiched between two matrices of thin films which are formed of material having a rectangular hysteresis characteristic, the films being deposited as mirror images on respective substrate so that a pair of adjacent films together form a substantially closed magnetic circuit at the junction of the associated column and row conductors. As shown, in Fig. 4, each substrate 1, which may be an insulation material such as ceramics, glass, germanium, silicon, mica or a synthetic resin, or a non-magnetic material such as silver, copper, stainless steel or aluminium, has grooves 2a, 2b, 2c to accommodate the coordinate and read-out conductors and has a matrix of thin film coatings 3 which may be deposited by evaporation, plating or spluttering. The films may alternatively be formed by adhering foils to the substrates. The films extend across the grooves, and when the two substrates are brought together, as shown in Fig. 3B, a closed magnetic circuit is provided about each conductor junction. The films and grooves may alternatively be arranged as shown in Fig. 5. An alternative construction is to have two identical substrates, Fig. 6, each having a deposited film in the form of a cross and a set of grooves along one co-ordinate only. The two substrates are assembled with their respective grooves at right angles to form the matrix assembly. The constructional method disclosed may also be applied to a system using two cores M1, M2, Fig. 7, for each bit. In operation, the cores are brought to opposite remanent states by a pulse Ir, Fig. 8, applied to winding R. A writing pulse Iw of lesser amplitude and having a polarity Iwl or Iw0 depending on the binary digit 1 or 0 which it represents is then applied to winding W at the same time as an equalamplitude setting pulse Is appears in winding R. If the write pulse is Iwl core M1 is switched, while core M2 is switched for a write pulse Iw0. When the next pulse Ir is applied the cores are brought back to their opposite remanent states and a positive or negative output pulse is induced in output winding P respectively indicative of a stored binary one or zero. The operational equivalant of the two-coreper-bit store is obtained by the construction in Fig. 10 in which the conductors R and W intersect at right angles between two disc films 2 deposited on respective substrates 1, the equivalent of the two cores being obtained in the magnetic material lying along two coordinates axes each at an angle of 45 degrees to the R and W conductors. This arrangement may be formed into a matrix having coordinate conductors Wa -Wc and Ra-Rc as shown in Fig. 13. An alternative construction is the use of strip films 2, Figs. 12A and 12B, associated with three grooves 3 in which the R and W conductors are positioned as shown. This arrangement likewise may be used in a matrix, Fig. 14. Instead of groove substrates, conductors 4 in strip or ribbon form spaced by thin insulating layers 5 may be used. Using this method of construction, the equivalent of Figs. 10 and 12 is shown respectively in Figs. 15B and 16B. An alternative to Figs. 12 and 16B is shown in Fig. 17 in which the R conductor has parallel paths and so permits the use of two conductor paths only.