Optical scanning device with coarse and fine scanning control

摘要

An optical scanning device includes an object lens for focusing a light beam onto a recorded medium having a helical data track. A tracking regulation circuit guides the object lens along the data track. The tracking regulation circuit includes a coarse drive circuit for driving the optical scanning device and a fine drive circuit for adjusting the object lens. The optical scanning device and the object lens have optical axes which normally are aligned. Deviations of the optical axes from alignment are measured and regulation signals are generated for the coarse drive circuit in accordance with the deviations.