Patent ID: 7130250

Claim:
An optical disk apparatus for recording or reproducing data to or from a rotating information medium which has at least one information plane, the apparatus comprising: a converging section operable to converge an optical beam to irradiate the converged beam onto the rotating information medium; a focus moving section operable to move the converging section in a direction normal to the information plane of the information medium; an optical detection section having a light receiving area divided substantially concentrically into plural areas, and being operable to receive reflected light from the information medium and output a signal corresponding to the amount of the reflected light; a plane vicinity detecting section operable to generate a vicinity detection signal based on a signal from the optical detection section, the vicinity detection signal continuously varying so as to have one maximum point while a beam spot of the optical beam moves from the surface to the information plane of the information medium; a search driving section operable to generate a driving signal for approaching or separating the beam spot of the optical beam with respect to the information medium; a focus error detecting section operable to generate a signal corresponding to an error of a focus position of the optical beam with respect to the information plane or the surface of the information medium; a focus control driving section operable to generate a signal for driving the focus moving section so that the beam spot of the optical beam follows the information plane of the information medium in accordance with the signal from the focus error detecting section; an information plane determining section operable to determine whether or not the beam spot of the optical beam is located in the vicinity of the information plane of the information medium based on signals from the plane vicinity detecting section and the focus error detecting section; and a focus pull in section operable to select and supply either of the signal from the focus control driving section or the signal from the search driving section to the focus moving section in accordance with a signal from the information plane determining section.