OPTICAL DISK ACCESS DEVICE

摘要

PURPOSE:To bring a positioning means to an object track in one accessing operation by using separately a differentiation type speed detection means or a period measuring type speed detection means to an access device of an optical disk depending on the relative speed of the positioning means to the disk. CONSTITUTION:When the relative speed between the positioning means and the disk is slow, the detected speed of the differential speed detection means 7 is selected and when the relative speed is fast, the detected speed of the period measuring speed detection means 6 is selected by the speed changeover means 8 and the result is inputted to an error amplifier means 10 as a detected speed. When the positioning means 3 starts movement toward the object tracks, a track count means 12 subtracts number of crossed tracks from the track counter having the track number inputted from an external device 13 at first and to be accessed by using a tracking error signal generated by the position detection means 4. Thus, the speed command means 9 decreased the commanding relative speed in proportion to the root of the distance up to the objective track as the object track is approached.