| 摘要 |
PURPOSE:To attain automatic calibration of an error of a head speed detection means by calculating an actual speed of a head from a track cross signal and time counter, correcting an object speed stored in a ROM based on the ratio of the object speed to the actual speed and storing the result into a RAM. CONSTITUTION:A CPU 106 counts the track cross detection signal to calculate the remaining track number with respect to the object rack and references a ROM 108 to read object speed information. Then the object speed subject to DA conversion and the detected head speed by the speed detection means 101 are compare by a subtractor 102 and the result controls the head drive speed. While the detected speed and the object speed are kept to be a constant value, the CPU 106 decides the actual speed of the head based on the output of the time counter built therein and the track clock cross count to obtain the ratio with the object speed. The object speed of the ROM 108 is corrected based on the ratio, the result is written in a RAM 109, the value is used thereafter and the error of the means 101 is calibrated automatically substantially.
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