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US 4,394,621 AGranted
Electronic velocity measurement especially for self-clocking write head
AssigneeInternational Business Machines Corporation
InventorJames E. Rohen
Life of this patent
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Abstract
A time base signal for controlling the recording of binary data is developed by measuring the velocity of a magnetic record. The velocity is measured by providing an inductive read head and a magnetoresistive read head which sense the same flux field on the magnetic record. The difference in the outputs of these read heads is a measure of the record velocity.
Claims2
Velocity measuring apparatus for producing an electrical measurement of the velocity of an object having at least one magnetically sensible mark thereon, wherein the improvement comprises:
- an induced current magnetic field sensing device,
- a variable resistance magnetic field sensing device,
- means supporting said devices closely adjacent, one to another, for encountering said mark during substantially the same state of relative motion with respect to said object, and
- means responsive to a signal output from each of said devices for producing said electrical measurement.
1 more element
Dependencies are inferred from the claim text.