Patent ID: 7151721

Claim:
An optical reproducing apparatus for reproducing information on a medium comprising: a light source; an optical system for irradiating a light beam generated by the light source on the medium, the optical system including an automatic position controller enabling auto-focus control and automatic tracking control for controlling a lens actuator; a detector for detecting a reflected light from the medium; and reproduction means for reproducing information on the medium by using a signal from the detector; wherein the medium comprises: a substrate, grooves and lands alternately formed on the substrate in a radial direction, the grooves and the lands both serving as recording tracks, the recording tracks having information recorded thereon and being divided into recording units in a circumferential direction, each the recording units having a prepit area in a non-groove portion of the substrate, a first prepit representative of VFO information being provided in the prepit area, and a second prepit representative of address information being provided in the prepit area, the first prepit and the second prepit being located on both sides of a center line of one track, the first prepit and the second prepit being formed on each side of the center line of the one track so as to be shared with an adjacent track which is adjacent each side of the center line of the one track, and every prepit including the first prepit and the second prepit not existing at opposing positions on both sides of the center line of the one track.