Back to results
US 4,363,038 AGranted
Contact duplication system using anisotropic magnetic recording media
AssigneeMinnesota Mining and Manufacturing Company
InventorRichard E. Fayling
Life of this patent
Estimating the term…
Abstract
A system for contact duplication is disclosed wherein anhysteretic magnetization of a copy medium occurs using an anisotropic master medium wherein the two media are held in surface contact and an AC bias magnetic field is applied along the hard axis of the master media.
Claims15
A signal duplicating system comprising:
- (a) a master magnetic recording medium having magnetic anisotropy associated with at least one easy and one hard axis of magnetization, said medium being characterized by an initial remanent magnetic moment after a substantially saturating magnetizing field is applied along an easy axis of said medium, and being further characterized by a subsequent remanent magnetic moment of at least 40% of said initial remanent magnetic moment after an AC magnetic field having an intensity equal to twice the easy axis coercive force of said master medium is applied parallel to a hard axis of the medium;
- (b) means for impressing a magnetic recording pattern on said master recording medium in the form of a localized magnetic field pattern therein;
- (c) a slave magnetic recording medium capable of becoming remanently magentized when an external magnetic field is impressed thereon;
- (d) means for temporarily maintaining said master and slave magnetic media in surface contact with substantially no relative movement therebetween;
- and
- (e) means for applying an AC bias magnetic field to the contacted media parallel to said hard axis of said master medium to promote duplication of a magnetic pattern on said master media to said slave media without erasing said pattern on said master medium.
3 more elements
A signal duplicating method comprising:
- (a) providing a master magnetic recording medium having magnetic anisotropy associated with at least one easy and one hard axis of magnetization, said medium being characterized by an initial remanent magnetic moment after a substantially saturating magnetizing field is applied along an easy axis of said medium to establish a remanent state therein, and being further characterized by a subsequent remanent magnetic moment of at least 40% of said initial remanent magnetic moment after an AC magnetic field having an intensity equal to twice the easy axis coercive force of said master medium is applied parallel to a hard axis of the medium;
- (b) impressing a magnetic recording pattern on said master recording medium in the form of a localized magnetic field patterns therein;
- (c) providing a slave magnetic recording medium capable of becoming remanently magnetized when an external magnetic field is impressed thereon;
- (d) temporarily maintaining said master and slave magnetic media in surface contact with substantially no relative movement therebetween;
- and
- (e) applying an AC bias magnetic field to the contacted media parallel to said hard axis of said master medium to promote duplication of a magnetic pattern on said master media to said slave media without erasing said pattern on said master medium.
3 more elements
Dependencies are inferred from the claim text.