| 摘要 |
PURPOSE:To improve linear characteristics in a whole detecting range and to hold excellent linear characteristics in spite of a change in environmental temperature by dividing the whole detecting range into several ranges, approximately distributing the divided range into plural linear characteristics and changing the linear characteristics based on a time base in accordance with an accessing operation. CONSTITUTION:A computing element 25 is provided with a memory storing means 25a for storing characteristics obtained by dividing the whole detecting range of an optical position sensor 6 into several ranges and approximately distributing the divided ranges into plural linear characteristics and a memory rewriting means 25b for rewriting the contents of the memory 17 in accordance with the accessing operation of a mobile part 4. Since correlation between a sensor position signal and a track demodulation signal is changed based on the time base, the linear characteristics are changed from the time base by using a track demodulation signal 15 and a sensor position signal 21 inputted at every accessing operation. Consequently, the non-linear characteristics of the position sensor can be improved, the linear characteristics of the position sensor can be always held in spite of a change in the environmental temperature and highly accurate positioning can be attained.
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