DEVICE AND METHOD FOR MEASURING VIBRATION AMOUNT AND LOOP DESIGNING METHOD

摘要

PURPOSE: A vibration amount measuring device and a method thereof, and a method for designing a loop are provided to reduce the designing time and increase the designing precision of an optimum focus and tracking controller by measuring the focus and tracking vibration amount by a disc access time. CONSTITUTION: A vibration amount measuring device includes an error gain controller for controlling a focus generated by the rotation of a disc and amplitudes of a tracking errors to be kept uniformly, a loop gain controller for comparing a closed loop phase of the tracking loop and the focus with a predetermined reference closed loop phase for compensating a gain deviation of an actuator, to keep the gains of the tracking loop and the focus uniformly, and a measuring unit for computing a vibration amount from the errors controlled by the error gain controller and the loop gain controller, the focus of the disc compensated by the errors, and an output from a controller which controls tracking.