| 摘要 |
PURPOSE:To prevent unstable seek errors due to defects of a servo track by differentiating an AGC control voltage to detect the defect of the servo track in advance. CONSTITUTION:A read signal from a servo head 1 is inputted to an AGC circuit 11, an AGC output is given to a servo system and an AGC control voltage generating circuit 12 as a servo signal 2, and the circuit 12 applies an AGC control voltage 3 to the circuit 11 so that the output level of the circuit 11 is constant. Further, the voltage 3 is differentiated by a differentiation circuit 13, a comparator 14 compares the differentiated output with a prescribed value to detect the defect of the servo track. Thus, the output of the comparator 14 is reported to a host device as an error of the seek system. |
