公开(公告)号：HK138894A

公开(公告)日：1994-12-16

申请号：HK138894

申请日：1994-12-08

Applicant: IBM

Inventor： KROUNBI MOHAMAD TOWFIK ,  VOEGELL OTTO ,  TSANG CHING HWA

IPC: G11B5/39

公开(公告)号：GB1079500A

公开(公告)日：1967-08-16

申请号：GB5230364

申请日：1964-12-02

Applicant: IBM

Inventor： CHANG HSU ,  MEE CHARLES DENIS ,  MIDDELHOEK SIMON ,  VOEGELL OTTO

IPC: G11C7/02 ,  G11C11/14 ,  G11C11/15 ,  H01F10/30

Abstract: 1,079,500. Circuits employing bi-stable magnetic elements. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 23, 1964 [Jan. 13, 1964], No. 52303/64. Heading H3B. [Also in Division H1] In a magnetic uniaxial film element store in which information is stored by magnetizing the film along one direction or the other along the easy axis, the film element having an associated range or associated ranges of values of magnetization along the hard axis variation within which can cause, by a creeping action, the switching or destruction of the stored information, the element is subjected to a disturb magnetic field which acts along the hard axis and varies within the range or a range and a bias magnetic field along the hard axis, the resultant of the bias and disturbs fields lying outside the associated range or ranges. It is stated that wall creeping is produced in both thick and thin magnetic films when the films are subjected to alternating fields in the hard direction of value 0À2 H K to 0À3 H K for thick films and 0À3 H K to 0 for thin films, Figs. 3, 4 (not shown). Since in word orientated memory systems the word field in a selected word or line can produce a strong disturb field in the hard direction in the elements of lines adjacent to the selected word these elements may be switched. In accordance with the invention an electrical conductor or strip 50 is disposed over ground plane 12À1 to cover the film elements 10 and the current therethrough from battery 56 is adjusted by resistor 54 so as to provide a magnetic field 32À1 in the hard direction and having a value at least 0À2 H K but not greater than 0À3 H K . Storage in the film is by passing a current of the appropriate polarity through the selected word line 18À1, 18À2, 18À3 coincidently with a current through the selected bit conductor 16À1, 16À2, 16À3. Read-out is by energization of the selected word line 18 such that the field produced thereby is less than H K to enable non-destructive read-out. When thin films are employed the bias field must be in the direction of the disturb fields which is possible in the application of the invention to a magnetic store since a unipolar word drive pulse is employed. If thick films are employed, i.e. greater than 900 Angstroms, the hard axis bias field may be in or against the direction of the disturb fields provided the disturb fields are approximately 0À6 H K . Random fields may be eliminated by shielding. In the arrangement of Fig. 6 (not shown) the strip conductor of Fig. 5 is replaced by a Helmholtz coil arrangement. The bit and drive lines need not be orthogonal.