Patent GB-1522707-A (GB)
Title: Data apparatus using a lattice
IPC: G11C13/06
Filed: 1975-10-31
Abstract: 1522707 Magnetic storage arrangements INTERNATIONAL BUSINESS MACHINES CORP 31 Oct 1975 [31 Dec 1974] 45256/75 Heading H3B A lattice of magnetic bubbles may be expanded in one or both directions and subsequently contracted to its original dimensions. Expansion in the horizontal direction only is shown in Figs. 2A and 2B, expansion in the vertical direction being prevented by energized conductors 24, a magnetic overlay, or etched grooves in the bubble-supporting garnet or amorphous magnetic material. An arrangement permitting controlled expansion in both directions is shown in Fig. 3, lattice dimensional control being effected by three conductor loops L1, L2, L3 assisted by magnetic soft elements 34. Conductor loop L1 is normally energised to confine the lattice, but this current is gradually reduced and conductors L2, L3 energized in turn to effect controlled lattice expansion, Fig. 4A (not shown). A converse pattern of current energization reduces the lattice to its original dimensions, Fig. 4B (not shown). Included in Fig. 3 is a shift register SR the magnetic bubbles B' of which couple with magnetic bubbles 36 when the lattice of bubbles B is expanded. Shift registers extending between respective bubble generators and sensors may be provided along opposite faces of the expanded lattice, Fig. 5 (not shown). Data may be stored either within the lattice itself or in an information layer magnetically coupled to the lattice. Data stored within the lattice.-As described in Specification 1454451, information is contained within the lattice in the form of the bubble chiral state or the number of block lines within a bubble domain wall. In either case bubbles are distinguished according to direction of movement in a gradient magnetic field, such a field being provided by the conductor loops L1-L3 when a lattice is expanded. A bubble sensing arrangement is shown in Fig. 7, in which only those bubbles B of a specified character move in a direction 58 when the lattice is expanded such as to couple with respective magneto resistive sensors A1-A3, B1-B3 ... The remaining bubbles move in a direction 56 sufficiently angularly displaced from direction 58 as to avoid coupling with the sensor matrix 60 which is formed on a glass substrate 62. In an alternative arrangement, Fig. 8, the gradient field is provided by one or more scanning domains SB in a further magnetic bubble layer 70, a search domain following a scanning path 74 so as to couple in turn with each of the bubbles B in an expanded lattice. As each lattice bubble is influenced by a scanning bubble SB, it is deflected in a characterising direction so as to either couple or not with a magneto resistive sensor A1-A3 in a sensing matrix 60. Data stored in an adjacent layer.-In Fig. 9 the lattice is contained in bubble layer 20, and information is stored in adjacent bubble layer 80 in the form of presence or absence of bubbles Bi in a matrix pattern, each bubble Bi being located by magnetic coupling with an underlying lattice bubble B. The information layer additionally includes magneto-resistive sensors each positioned at a location which corresponds to that of a respective lattice bubble when the lattice is expanded. Consequently when expansion takes place the coupled information bubbles are similarly displaced and the information stored read out. If required lattice bubbles may be annihilated by nucleators 82. A further arrangement, Fig. 11A, has the lattice arranged so as to expand linearly into work areas 1 and 2. In a modification, Fig. 11B, expansion into buffer zones 110, 112 is effected by reducing stripe domains 114 which repulse the magnetic bubbles B, the domains being subsequently extended to contact the lattice. Two coordinate expansion is possible by this method. Such arrangements enable the information bubbles in the overlying information layer to move into work areas for nucleation writing and annihilation, Fig. 12. As shown a work area includes a matrix of magnetic elements 122 coupled to row and column conductors 1-16 and positioned over the bubble positions in an expanded lattice. By energising a selected row and a column line from digit and selection current sources 124, 126, the coincidently-energized magnetic element can nucleate or annihilate a magnetic information bubble in the expanded pattern to which it is coupled. An alternative arrangement, Fig. 13 (not shown), comprises a matrix of magneto resistive detectors in positions corresponding to the magnetic elements. In a combination of nucleators and detectors, Fig. 14 (not shown), a matrix of magnetic elements is located in one part of a work area and a similar matrix of magneto resistive elements in the other part.