The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 25, 2003
Filed:
Jan. 27, 2000
Ian Macdonald Green, London, GB;
Central Research Laboratories Limited, Hayes, GB;
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.