Head TEST method
Original Publication Date: 2002-Mar-30
Included in the Prior Art Database: 2003-Jun-21
1 Disclosed is the method to test GMR head in terms of instability and center shift. Test algorithm is described below. By using this algorithm, both amplitude instability and center shift could be expressed as numeric number so that bad head could be rejected by simply setting criteria. Write an amplitude burst pattern at the center of the track.(A in fig1),write second pattern at little off track position(B in fig1), write third pattern at opposite off track position(C in fig1) Read these three pattern while read head is on the center of the track, read back amplitude from them are expressed as （（（ （（（（（（（（（Va x Vb Vc（（（ where Va is readback amplitude of pattern A,Vb is readback amplitude of pattern B,Vc is readback amplitude of pattern C. k is also expressed as ｋ ｋ（ｋ（（（（[Wr Xoff Ww-Wr)] Wr（（（ｋ where Wr is the read head width, Ww is the write head width, and Xoff is off track position where pattern B and C were written..