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, 1992
Filed:
Apr. 23, 1991
William A Palm, Minnetonka, MN (US);
Seagate Technology, Inc., Scotts Valley, CA (US);
Abstract
A device for braking a rotating magnetic disk in a magnetic storage system senses a back EMF generated by a drive spindle motor. By electrically shorting the coils in the drive spindle motor the rotation of the magnetic disk is stopped. The back EMF is compared with a reference voltage. The reference voltage is selected so that the rate of rotation of the magnetic disk is large enough that a magnetic head 'flies' over the surface of the disk, but small enough so that surge currents in the drive spindle motor will not damage the motor coils. Field effect transistors are used to electrically short the coils. A holding capacitor holds a voltage on the gates of the FETs upon loss of power to the magnetic storage system. A reset circuit draws charge from the holding capacitor upon power-up of the storage system.