| 摘要 |
PROBLEM TO BE SOLVED: To reduce an eccentric amt. at the recording and reproducing time. SOLUTION: Eccentric amts. Aa, Aa(π/2), Aa(π) and Aa(-π/2) under the state of rotating a chucking plate from a temporary chucking state by 0,π/2,πand -π/2 are obtained (ST1-ST5), and by using these eccentric amts., a discrepancy Ac between the center of the chucking plate and the center of a rotary shaft of a spindle motor and a discrepancy Am between the center of a center hole of a disk and the center of a track are obtained, and moreover, a phase difference between Ac and Am (ST7). Then, the chucking plate is rotated from the temporary chucking state by 180 deg.-θ, and the disk is finally chucked up on the chucking plate under the state of the direction of the discrepancy Ac opposite to the direction of the discrepancy Am (ST8). Since the direction of the discrepancy Ac and the direction of the discrepancy Am are opposite to each other, the eccentricity of the discrepancy Ac and the eccentricity of the disprepancy Am are offset against each other, and hence the eccentric amt. at the recording and reproducing time is reduced.
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