Contact duplication of magnetically recorded information without the use of a transfer field
AssigneeEastman Kodak Company
InventorsFrederick J. Jeffers, Charles F. Brucker
Life of this patent
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Abstract
Apparatus for, and a method of, duplicating magnetically recorded information by contact transfer from a master medium to a slave medium in the absence of a transfer field. The slave medium comprises a dilute concentration of magnetic particles productive of a demagnetization field that is negligible compared to an external magnetic field of the master medium in its contact-transfer zone. The absence of an appreciable demagnetization field in the slave medium enables the external magnetic field of the master medium to be virtually unopposed in effecting the magnetization of the slave medium.
Claims9
A system for duplicating magnetically recorded information by contact transfer from a master medium to a slave medium, said system comprising:
- a) said master medium having a sufficiently high coercivity and remanence so that information recorded thereon is productive of a magnetic field the intensity of which, in an external contact-transfer zone, is at least as greater as the remanent coercivity of said slave medium;
- b) said slave medium having a demagnetization field that is negligible compared to the magnetic field of said master medium in its contact-transfer zone;
- and
- c) a mechanism for transporting said slave medium through the contact-transfer zone of said master medium in non-slipping engagement therewith, to effect a magnetization of said slave medium that is the mirror image of the magnetization pattern recorded on said master medium by direct magnetization of said slave medium by said magnetic field of said master medium without the use of an independent magnetic transfer field, whereby the absence of an appreciable demagnetization field in said slave medium enables the external magnetic field of said master medium to be virtually unopposed in effecting said magnetization of said slave medium.
A method for duplicating magnetically recorded information by contact transfer from a master medium to a slave medium of relatively high coercivity in the absence of a transfer magnetic field, said method comprising;
- a) recording information on a master medium having a sufficiently high coercivity and remanence so that the information recorded thereon is productive of a magnetic field the intensity of which, in an external contact-transfer zone, is at least as great as the remanent coercivity of the slave medium;
- and
- b) transporting the slave medium through the contact-transfer zone of the master medium in non-slipping engagement therewith, the relatively high-coercivity slave medium comprising a relatively dilute concentration of magnetic particles productive of a demagnetization field that is negligible compared to the magnetic field of the master medium in its contact-transfer zone, to enable the external magnetic field of the master medium to be virtually unopposed in effecting a magnetization of the slave medium that is a mirror image of the magnetization pattern recorded on the master medium.
Dependencies are inferred from the claim text.