GB850650A - Improvements in or relating to magnetic storage devices - Google Patents

Abstract

850,650. Circuits of bi-stable magnetic elements. STANDARD TELEPHONES & CABLES Ltd. Nov. 12, 1956, No. 34478/56. Class 40 (9). [Also in Groups XXXV and XL (b)] A magnetic storage element comprises a magnetic cell of material with a square hysteresis loop having hole through which current carrying conductors pass so that current flow produces a first magnetizing force tending to saturate the cell around a closed path, and includes means for producing a second magnetizing force acting, at two points tangentially to.the first force so that at one of these points the two forces oppose thus inhibiting the establishment of remanent flux round the closed path. As shown in Figs. 8 and 9 two conductors pass through an aperture radius r and each carries a half-current, the combined current being such that at a distance 2r the magnetizing force shown by curve 12 has a value K just sufficient to saturate and at radius r the value is 2K. A second magnetizing force 13 is applied so that the combined field is shown by curve 14 and on the radius to point B the combined field varies between K and O and this is insufficient to saturate the material so preventing the production of circular remanent flux which "sets" or operates the cell. Fig. 10 shows 'a cell 39 which is movable between the poles of a magnet 41 and so are under the influence of an inhibiting flux which prevents conductors 42 setting the cell. A single piece of magnetic material may have several holes to provide a number of cells. are all parallel, each spindle being embedded at one end in a base of synthetic resin formed by injection moulding. The running surfaces are formed of synthetic resin (a polyamide) to reduce friction. A spindle 9 carrying the fingerplate 8 has a plastic sleeve 10. A gear-wheel 17 and a cap 12 housing the return-spring 13 or fixed to the end of the spindle 9. The wheel 17 drives a pinion 20 running on spindle 3. The pinion 20 is formed with a bush 21 carrying a cam disc 25 operating impulsing-springs 39, 40. A cam 26, friction coupled to the bush, enters a slot (not shown) in spring40 during the returnmotion of the finger-plate and acts as a stop to prevent spring 39 following 40 as the cam turns. The friction brake governor on spindle 2 is driven firmly only during the return motion by gear 22 and pinion 28, the gear 22 running on the bush 21 but being coupled thereto by a spring 23 so that it is only lightly driven in the forward direction. A projection 41 on gearwheel 17 allows contacts 37, 38 to close only when the transmitter is in the normal position. The transmitter is enclosed by a plastic cap 44 beneath the finger-plate and a transparent, plastic cap 52 at the rear, both caps being snapped into place.