"On Track" Detector
Original Publication Date: 1978-Jun-01
Included in the Prior Art Database: 2005-Feb-21
The function of an "On Track" detector in a track-following servo disk file is to prevent writing of data when the read/write head is further than a predetermined distance from the track center, which may occur because of invalid control commands or failure of the track-following servo loop. Conventionally, this has been achieved by generating an "On Track" signal through threshold detection of the head position error signal (PES). However, noise spikes on the PES due to disk coating irregularities can result in the write circuits being erroneously disabled. Mere filtering of the PES to remove high frequency noise may increase the response time unacceptably.