Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-09-12
2004-08-10
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603070, C029S603080, C029S603090, C029S606000, C083S684000, C083S685000, C083S686000, C083S948000, C360S133000, C360S135000, C451S041000, C451S054000, C451S063000
Reexamination Certificate
active
06772507
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a magnetic recording medium having a disc-shaped flexible slave medium accommodated in a case, onto which servo signals are recorded by a magnetic transfer method.
2. Description of the Prior Art
To realize large recording capacity of a magnetic recording medium having a disc-shaped flexible slave medium accommodated in a case, which is a so-called flexible disc, so-called tracking servo technology for reproducing signals with a high S/N ratio by scanning tracks with a narrow width precisely by means of a magnetic head has played an important part.
Servo signals for tracking, address information signals, reproducing clock signals and the like are previously recorded on one circumferential track at certain intervals in the slave medium (hereinafter referred to as a servo write), and a magnetic head reads the signals to correct its own position, whereby the magnetic head can trace the track accurately.
The existing servo write is prepared by recording the signals one track by one track for each slave medium by use of a servo write apparatus exclusively used for that purpose. Recording capacity has a tendency to be highly densified, and the servo write take a long time. For this reason, a servo write step occupies a large part of the manufacturing cost, and lowering of the cost is desired.
In view of the above described circumstances, conceived is a technology concerning a magnetic transfer method in which the servo write is not carried out one track by one track, but carried out simultaneously for the entire surface of the slave medium. In this magnetic transfer method, magnetic field for transfer (hereinafter referred to as transfer magnetic field) is applied to a master medium and the slave medium in a state where both of the mediums are brought into close contact with each other, and thus a magnetic pattern corresponding to information such as servo signals borne on the master medium is magnetically transferred to the slave medium. As to this magnetic transfer method, disclosures have been made in, for example, Japanese Unexamined Patent Publication Nos. 63(1988)-183623, 10(1998)-40544, 10(1998)-269566 and the like.
In the manufacturing steps for manufacturing the magnetic recording medium including the magnetic transfer, a measure to cope with demands for securement of a recording accuracy of the servo signals, securement of quality and the like is necessary. Therefore, removing distortion of the material, increasing flatness of the disc, removal of dust, checking and the like must be carried out. Moreover, a manufacturing system must be constructed by effectively carrying out these processe.
SUMMARY OF THE INVENTION
The present invention was made in consideration of such circumstances, and the object of the present invention is to provide a method of manufacturing a magnetic recording medium capable of having a disc-shaped flexible slave medium accommodated in a case, onto which servo signals are recorded with high quality and efficiency by a magnetic transfer method.
A method of manufacturing a magnetic transfer medium of the present invention, which has a disc-shaped flexible slave medium accommodated in a case, onto which servo signals are recorded by a magnetic transfer method, comprises the steps of: cutting an original sheet into discrete webs, each having a predetermined width (slitting step); obtaining a disc-shaped slave medium by punching the web (punching step); removing distortion of the web or the slave medium (thermo step); smoothing a surface of the slave medium (burnishing step); fixedly attaching a center core to the slave medium (center core attachment step); performing a magnetic transfer while allowing a master medium bearing servo information and one of the web and the slave medium to be brought into close contact with each other (magnetic transfer step); incorporating the slave medium into the case (assembly step); removing dust on the slave medium after completion of the assembly step (cleaning step); checking the servo signals magnetically transferred to the slave medium (verifying step); and packing the magnetic recording medium as a product (packing step).
The method of manufacturing a magnetic recording medium preferably comprises the slitting step, the punching step, the thermo step, the burnishing step, the center core attachment step, the magnetic transfer step, the assembly step, the cleaning step, the verifying step and the packing step in this order.
The magnetic transfer step should be carried out in such a manner that the slave medium is first subjected to DC magnetization in a track direction, the slave medium is allowed to be brought into close contact with the master medium for use in the magnetic transfer, on which a magnetic layer is formed in a micro uneven pattern corresponding to information to be transferred, and a transfer magnetic field is applied to the master medium and the slave medium in a direction approximately reverse to the initial DC-magnetization direction for a surface of the slave medium.
According to the present invention as described above, the method of manufacturing a magnetic recording medium comprises the slitting step, the punching step, the thermo step, the burnishing step, the center core attachment step, the magnetic transfer step, the assembly step, the cleaning step, the verifying step and the packing step, whereby it is possible to manufacture the magnetic recording medium having the disc-shaped flexible slave medium accommodated in a case, onto which servo signals are recorded with high efficiency and high quality.
The method of manufacturing a magnetic recording medium which comprises the above-described step in this order can cope with demands for an increase in quality and efficiency of manufacturing the same.
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patent: 10-269566 (1998-10-01), None
patent: 10-40544 (1999-08-01), None
“Theory of antiferromagnetically coupled magnetic recording media”; Schabes, M.E.; Fullerton, E.E.; Margulies, D.T.; Magnetic IEEE Transactions on , vol.: 37, Issue: 4, Jul. 2001 pp.: 1432-1434.*
Patent Abstract of Japan 63-183623 Jul. 29, 1988.
Fuji Photo Film Co. , Ltd.
Kim Paul
Sughrue & Mion, PLLC
Tugbang A. Dexter
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