Method to Measure the Amount of Off-Track
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a method to measure the amount of off-track in a small hard disk drive having a stepping motor, etc., which can be driven by so-called micro-step mode to move the head access mechanism. In a standard hard disk drive, PES (Position Error Signal) is used to set the head access mechanism on-track in its servo system. The PES shows the value in proportion to the amount of off-track. At on-track position PES value is zero (Fig. 1). This method consists of getting a correlation of PES value versus off-track moving the head intentionally by micro-step mode. Then the amount of off-track can be calculated by using the correlation curve. The method is explained in the following way. (Fig. 2) 1. Read PES value with certain head and at certain track, and at this point assume off-track is zero. 2.