Tilt servo system for correcting tilt angle of light beam in information read/write apparatus

Abstract

A highly accurate and stable tilt servo system is provided. A liquid crystal device for phase correction is driven based on drive data stored in a lookup memory to thereby make a tilt correction. Upon pre-processing, a pickup is moved to a predetermined position on the inner circumference of a disc for a tilt correction to employ tilt error data delivered from a tilt sensor as reference tilt error data and drive data served for the tilt correction as a reference tilt correction quantity. After the pre-processing, when the pickup is moved, the difference between the tilt error data delivered from the tilt sensor at each position of movement and the reference tilt error data is employed as a relative correction quantity. The drive data equivalent to the relative correction quantity is acquired from the lookup memory. The drive data acquired is added to the reference correction quantity to thereby determine a tilt correction quantity. The liquid crystal device is driven based on drive signals equivalent to the tilt correction quantity.