DC Offset Correction With Fast Recovery Mode in WRITE to READ Recovery Times for Sector Servo Hard Disk Files
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
The DC offset correction concerns magnetic disk 10 having interlaced data fields and servo fields and circuitry for reading and writing such fields by means of magnetic head 12. The DC offset correction is applied particularly to capacitor 14 (indirectly) from line 16 having an average offset DC voltage thereon so that the output of automatic gain control circuit 18 reduces, as shown in Fig. 4d instead of as shown in Fig. 4e on a change from WRITE mode to READ mode. The alternating servo fields and data fields are shown in Figs. 1 and 2. The circuit includes a common channel for servo information and data information between head 12 and data and servo detection circuitry 20. The common channel includes arm electronics (AE) module 22, amplifier 24 and automatic gain control circuit (AGC) 18.