| 摘要 |
PURPOSE:To attain accurate tracking by performing an offset correction and a gain coefficient correction corresponding to an absolute time versus servo information characteristic to eliminate access error. CONSTITUTION:Suppose that servo information (x) at disk loading is 0. Absolute time information (y) read by a pickup 2 in this case is fed to a control section4 and an offset value (b) is set as b=-T0 at an offset operating section 9-1, where T0 is the value of the information (y) at disk loading. When a T1 is given as a position designating signal y' at the 1st access, a servo information operating section 9-3 operates the servo information (x) as x=(T1-b)/k and outputs it. A basic gain coefficient (k) is represented by tantheta in a characteristic A shown in figure. When the information (y) from the pickup 2 moved by the information (x) is taken as T1', it is collated with the said T1, and a=(T1'-b)/T1=(T1'+ T0)/T1 is operated by a gain operating section 9-2 and the correcting gain coefficient (a) is set. The servo information (x) is calculated by an operation section 9-3 in the further accessing based on the operating equation y=akx+b. |
