Apparatus for reading permanently structured magnetic records
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United States of America Patent
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-
Feb 25, 2003
Grant Date -
N/A
app pub date -
Jan 27, 2000
filing date -
Apr 22, 1997
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An apparatus for reading permanently structured magnetic records having a first coercivity, comprising an oscillator having an inductive read head that is coupled to a circuit arrangement. At least one side of the read head sees an impedance that is larger than the impedance of the read head over the range of frequencies of interest, such that the read head provides an electrical signal in response to magnetic records having a second coercivity that is higher than the first coercivity (typically 2,000 to 5,000 oersteds). The electrical signal is derived from the voltage across the read head, which is preferably detected by a differential integrator that subtracts the voltages on either side of the read head to give a voltage difference, and integrates this difference over time.
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