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. 26, 2005
Filed:
Apr. 18, 2002
Molly Smith, Rochester, MN (US);
Molly Smith, Rochester, MN (US);
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
The microwaviness (i.e., surface waviness for wavelengths on the order of the length of the transducing head) of a recording disk surface is measured during manufacture as a quality control process. Preferably, the disk is measured using an actuator-mounted thermal sensor, comprising an electrical resistance element driven with a constant current. At small distances, the disk surface acts as a heat sink and variation in this distance will be detected as a change in resistance of the sensor. Preferably the sensor is initially used to characterize the gross waviness of the surface, and the actuator then follows this gross waviness to measure surface variations in the microwaviness range.