Potential Matching Disk Drive
Original Publication Date: 2001-Dec-25
Included in the Prior Art Database: 2003-Jun-20
This is part of the Potential Matching Arm Electronics (AE) system disclosure. This part applies to the Hard Disk Drive (HDD) portion. In most Hard Disk Drives, the spindle of the spindle motor is tied to a fixed potential such as ground. For example, a previous IBM Rochester HDD design ties the spindle potential to a fixed DC voltage. In this invention, the spindle and hence the disk pack's potential will be tied to a time varying potential that is determined by the AE with a potential matching circuitry. The idea here is to eliminate any common mode potential difference between the MR leads, the MR Shields, and the media to prevent disastrous arcing events or Electrical Over Stress EOS) from happening to the MR sensor and/or its shields. This invention eliminates arcing and EOS by equalizing potential differences between heads and media. Previously, a minimum spacing between head and media is imposed to reduce the incidents of arcing and EOS. The solution proposed in this invention effectively removes the spacing constraint while allowing the common mode potential on the MR sensor contacts to vary for performance reasons. While the idea presented here is best illustrated on a single head HDD design, it is possible to extend the concept to multiple head HDDs.