Radial tilt detector measuring an acceleration and distance of a beam spot

摘要

A radial tilt detector provided in an optical disc recording/reproduction apparatus includes an optical head for projecting a condensed beam of light on a recording surface of an optical disc and receiving a projected beam of light reflected from the recording surface, a focus actuator for focusing the condensed beam and a driver for outputting a drive signal to drive the focus actuator. The detector also includes an acceleration detector for outputting a signal indicative of an acceleration in a direction depending on an optical axis of the light beam, and a radial tilt calculation processor for receiving the acceleration signal and a signal indicative of the distance between the center of the optical disc and the projected position of the light beam on the recording surface where calculating the radial tilt is based on the received signals and the rotation velocity of the optical disc.