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:
Jun. 16, 1998
Filed:
Dec. 20, 1995
Charles Royston Patton, III, Murrieta, CA (US);
Donald George Stupeck, Laguna Hills, CA (US);
Western Digital Corporation, Irvine, CA (US);
Abstract
A self-contained disk drive actuator velocity controller for, independently of the disk drive microprocessor, placing the actuator into a velocity mode to slew the actuator to a pre-programmed velocity during parking, unparking, power interruption or microprocessor malfunction. The velocity controller may place the actuator into the velocity mode in response to a timeout signal that is generated in the event the microprocessor fails to update the current demand DAC within a predetermined timeout interval. The velocity controller may also place the actuator into the velocity mode in response to a supply power loss. In addition, the velocity controller may be triggered in response to a command from the microprocessor to park or unpark the actuator. The velocity controller monitors the BEMF generated by the actuator motor coil and adjusts the gain of the actuator motor driver accordingly until BEMF reaches a value that corresponds to the target velocity. The velocity controller measures the BEMF very accurately because it includes a nulling or calibration circuit that operates during tracking mode to nullify the effects of parasitic actuator coil resistance.