| 摘要 |
PURPOSE:To realize a high-precision data surface positioning system by providing an automatic gain control amplifying circuit to both a servo disk and not less than one data disk so that an output voltage ratio to a shift in track between information reproduced from the servo disk and that reproduced from not less than one data disks. CONSTITUTION:Servo surface information reproduced by servo head 6 is amplified 11 and servo automatic gain control amplifying circuit (S.AGC)12 generates a servo head position error signal with the gain where a maximum amplitude value in one- track movement is obtained. Then, this signal is differentiated by speed detecting circuit 13 and sent to summing amplifier 14 and at the same time, the output of S.AGC12 is inputted to data head position shift correcting circuit 15. Positioning information reproduced by data head 7, on the other hand, is amplified 16 and inputted to data AGC17 to generate a position error signal for unit track shift length from the input information. Thus, the position error signal of data head 7 inputted to circuit 15 is added to or substracted from the servo head position error signal according to its polarity and the result is sent to poststage summing amplifying circuit 14. |
