| 摘要 |
PROBLEM TO BE SOLVED: To detect reliable position without issuing an excessive alarm by more accurately detecting an alarm state. SOLUTION: A signal detector 21 has upper digit scale and lower digit scale of two or more tracks, and outputs respective detected values Sig.H and Sig.L. A counter position calculating section 23 determines a position PINC from the lower digit scale with an incremental manner, and an absolute position calculating section 24 determines a position PABS from the upper digit scale and lower digit scale with an absolute manner. A determined calculating section 60 decreases the alarm determination value AIVL used for alarm determination in a position data inspection section 25 within a predetermined interval of a slider from two positions after power-on, and widens it out of the predetermined interval. COPYRIGHT: (C)2006,JPO&NCIPI
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