Apparatus and method for track access

摘要

A track access apparatus is provided by the present invention in which a reference drive signal 90 proportional to the reference acceleration of a beam spot 22 is generated according to the contents of a track counter 34. A signal 92 indicating the reference velocity of the beam spot 22 is generated by an integrator 40 in accordance with reference drive signal 90. A signal 82 indicating the position of an objective lens 20 relative to a coarse actuator 26, a signal 84 indicating a relative velocity, and a signal 94 indicating the difference between the actual velocity of beam spot 22 and a reference velocity are supplied to coarse actuator 26 and to a fine actuator 28. Reference drive signal 90 is supplied to coarse actuator 26. The present invention makes maximum use of the rapid acceleration and deceleration capability of the coarse actuator and moves the beam spot to a target track accurately at high speed. The present invention also controls the velocity of the beam spot relative to an optical recording medium by using a simple hardware structure.