| 摘要 |
PURPOSE:To increase the tracking speed by providing a means for detecting the direction of eccentricity of the information track center to the turning center and a means for moving a disc recording medium in a direction opposite to the direction of eccentricity based on the result of detection by the eccentricity direction detecting means. CONSTITUTION:Two counters N, Ns in a controller 38 are reset to 0, and when the detected angle is advanced, the counter N is increased by 1 and a level of a signal (s) from a comparator 36 in this case is inputted as an R(e) corre sponding to an output signal (e) of an encoder 8. When the R(e) is at an H level, the counter Ns is increased by 1 and when R(e-1) is 0, the angle (e) is stored as the Es. Until a disc 2 rotates once, the operation above is repeated, and after the disc 2 rotates once, when the count of the counter Ns is within Nmax/2+ or -alpha, the detection is finished and when not, the preceding operation is repeated again. The rotation of the disc 2 is continued and the rotation of the disc 2 is stopped at an angle when the value of the output signal (e) of the encoder 8 is Es+Ns/2. Since the distance between an O2 and a P is nearly equal to r2, when the signal (s) goes to an L level, the O1 and O2 are almost made coincident by stopping the movement of the disc 2.
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