DEVICE FOR TRACKING DIAGONAL TRACK

PURPOSE:To move the servo stable point of a head and a diagonal track and to control it in a track arranging direction by executing a 1/4 (for one track part)-shifting to the four frequencies sequence of a reference pilot signal and generating an error voltage. CONSTITUTION:The output of a head switching circuit 6 is fetched through an LPF7 as a pilot signal PB. On the other hand, reference pilots f1-f4 are generated in a pilot generating circuit 10, a switch 8 is controlled by signals SEL1 and 2 of a switch control circuit 11, a successive selecting is executed, a multiplying 9 is executed by the signal PB and component difference of frequency difference DELTAfA and DELTAfB are generated. A track dislocation is detected through a circuit 21 and a switch 18 is controlled by a pulse ATFSW. When the output is a positive polarity, a right dislocation is obtained. An original error voltage A is fetched into a sampling circuit 19 by a pulse STA and a pulse TSB is given to an inserting pilot position. Then, an error voltage B is fetched into a sampling circuit 22. A deciding circuit 25 executes a comparing with a referring voltage and transmits signals S1 and S2. The phases of the signals SEL1 and 2 are changed through the control circuit 11 and the 1/4- shifting is executed to the feedback phase of the reference pilot signal. Then, the servo stable point is moved in the track arranging direction.