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:
Apr. 18, 1989
Filed:
Feb. 08, 1988
David M Hannon, Palo Alto, CA (US);
Donald E Horne, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A capacitive sensor for detecting capacitive contrast servo information on a disk in a data recording disk file includes a center-tapped inductor connected to a high frequency oscillator, a sensing probe formed on the back side of the slider and electrically coupled to one end of the inductor, and a dummy probe also formed on the back side of the slider and electrically connected to the other end of the inductor. The center-tapped inductor forms a primary coil of a transformer so that variations in capacitance sensed by the sensing probe provide a differential output signal in the inductor which is sensed by the transformer secondary coil. The probes, and their electrically conductive leads and terminal pads, are formed by thin film deposition techniques on the back side of the slider and are located with respect to the inductive read/write head so as to equally receive any noise generated by the read/write head. The dummy probe is spaced away from the air bearing surface of the slider so that the variation in capacitance due to the capacitive contrast pattern on the disk is received only by the sensing probe.