| 摘要 |
PURPOSE:To enable the head positioning with high accuracy and with a simple constitution by using a circuit which compares the numbers of pulse signals between odd and even servo tracks and detecting the position of the servo head according to the difference output of said comparison. CONSTITUTION:The total number of pulses SU corresponding to position signal pulses SP is proportional to the shift degree of the center position of a servo head 1 toward a servo track 3 from the boundary between servo tracks 2 and 3 under the control of a gate signal SG-1. While the total number of pulses SD corresponding to the pulse SP produced under the control of a gate signal SG-2 is proportional to the shift degree of the center position of the head 1 toward the track 2 of an odd number from the boundary between both tracks 2 and 3. Therefore these pulses SU and SD are counted respectively and a subtraction is carried out between these two count values to obtain a position shift degree of the head 1. In other words, the position of the head 1 can be detected.
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