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    MAGNETO-OPTIC TRANSDUCER
    21.
    发明专利
    MAGNETO-OPTIC TRANSDUCER 未知

    公开(公告)号：CA940229A

    公开(公告)日：1974-01-15

    申请号：CA115394

    申请日：1971-06-11

    Applicant: IBM

    Inventor： ALSTAD JOHN K ,  ARMITAGE JOHN D JR ,  BATE GEOFFREY

    IPC: G02F1/09 ,  G11B11/105

    Abstract: 1287864 Optical playback of magnetic records INTERNATIONAL BUSINESS MACHINES CORP 11 May 1971 [25 June 1970] 14186/71 Heading G5R A magneto-optical transducer using the Kerr effect and/or the Faraday effect comprises an optical prism having a magnetic film 34, Fig. 3, or 62, Fig. 11, on one surface and mounted so that a moving magnetic record, e.g. a tape 14, passes a second surface of the prism and an edge of the magnetic film. The magnetic film may be sandwiched between two such prisms of which the second surfaces may be coated with a reflecting material 69, Fig. 11, and may be curved, Fig. 8 (not shown), and/or grooved, Fig. 10 (not shown). Alternate layer of ferromagnetic and dielectric material may form the magnetic film (56), Fig. 10 (not shown). A bias field along the magnetic film may be produced by a pair of coils (54) mounted on either side of the transducer, Fig. 9 (not shown).

    25.
    发明专利
    未知

    公开(公告)号：DE1282714B

    公开(公告)日：1968-11-14

    申请号：DEJ0030922

    申请日：1966-05-25

    Applicant: IBM

    Inventor： ALSTAD JOHN KARL ,  BATE GEOFFREY ,  MORRISON JOHN R ,  SPELIOTIS DENNIS ELIAS

    IPC: G11B5/00 ,  G11B5/09 ,  G11B11/105 ,  G11B11/11 ,  G11C13/06 ,  G01D15/12

    Abstract: 1,143,836. Recording and playback; magnetic storage apparatus. INTERNATIONAL BUSINESS MACHINES CORP. 16 May, 1966 [26 May, 1965; 30 June, 1965], No. 21620/66. Headings G4C and G5R. [Also in Division H3] A cryomagnetic storage system operates by prerecording a predetermined pattern on a layer of magnetic material having a coercivity temperature relationship exhibiting a transition where the coercivity decreases rapidly with increasing temperature and maintaining the layer at a temperature such that the material is in a stable state close to the transition. To record a data bit in a particular position, the magnetization temperature condition of the material at that position is temporarily transferred to a metastable state on the other side of the transition, and the direction of magnetization is then charged. The magnetic material may be ferrous ferrite 12 supported on a tape 11 and is initially uniformly magnetized in a direction 15 opposite to a magnetic bias H applied at a recording station 13. The system is contained in uniform temperature enclosure just below the transition point. To record data bits at particular points along the tape, the tape is irradiated as the required point passes the recording station by an electron beam, to raise the temperature to above the transition. The bias field, which is not strong enough to overcome the steady magnetization at below the transition, is now strong enough, and magnetic switching occurs. The stored information may be read out by an optical system at 14 making use of Kerr or Faraday effects. By arranging that the prerecorded magnetization along the film alternates in direction at adjacent bit positions, the external biasing field may be dispensed with, the magnetization in surrounding bits being sufficient to reverse that of a particular bit when irradiated. A coincident current matrix store may comprise a magnetic film 40 initially magnetized in a direction opposite to a bias field H which is insufficient to reverse the magnetization. Coincident currents in the X and Y directions act to heat the film sufficiently at the selected bit to cause the transition to occur, whereupon the field H is sufficient to switch the film at that bit, to store information. An alternative matrix type store (Figs. 4A and 4B, not shown) provides wires at the bit locations normal to the memory plane, which is backed by an earthed sheet. Current to a particular wire heats the related location and enables the required transition to occur.

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