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US 4,395,447 AGranted
Medium for recording
OwnerYoshiro Nakamatsuinventor
Life of this patent
Estimating the term…
Abstract
A video disc includes a magnetic material applied thereon in such a manner that the orientation of said magnetic material is gradually intensified from the outermost track of the video disc to the innermost track thereof, starting from zero orientation at the outermost track.
Claims3
A recording medium comprising:
- (a) a recording disc,
- (b) a magnetic coating on said disc and with said coating having a thickness which decreases from a maximum to a minimum radially inwardly from the outer periphery toward the center of said disc to provide correspondingly increasing recording density from the outer periphery toward the center of said disc, said coating containing magnetic particles,
- (c) said magnetic particles being oriented relative to the surface of said disc generally inversely to the change in thickness of said coating and being essentially non-oriented at the periphery of said disc in the area of maximum coating thickness and increasing in orientation radially inwardly toward the center of said disc to a maximum uniform orientation in the area of minimum coating thickness, to thereby provide an essentially constant output for the recording medium from the disc periphery radially inwardly to the inner termination of said magnetic coating.
In the manufacture of a recording medium comprising a recording disc provided with a magnetic coating on said disc and with said coating containing magnetic particles, the steps of:
- (a) coating said disc with said magnetic coating so that the latter has a thickness which decreases from a maximum to a minimum radially inwardly from the outer periphery toward the center of said disc to provide correspondingly increasing recording density from the outer periphery toward the center of said disc,
- (b) and causing said magnetic particles on said coated disc to be oriented relative to the surface of said disc generally inversely to the change in thickness of said coating so that said particles are essentially non-oriented at the periphery of said disc in the area of maximum coating thickness and increase in orientation radially inwardly toward the center of said disc to a maximum uniform orientation in the area of minimum coating thickness to provide a recording medium having an essentially constant output from the disc periphery radially inwardly to the inner termination of said magnetic coating.
Dependencies are inferred from the claim text.