Optical disc device and method for focus control

An optical disc device for recording and reproducing a signal by irradiating a light beam onto an optical disc, the optical disc device comprising:

• a spindle motor which rotates the optical disc;
• a pickup including a laser beam source which generates the light beam, an objective lens which irradiates a light beam onto the optical disc, a photo detector which detects light reflected from the optical disc, and an actuator which shifts the objective lens in a focusing direction of the optical disc;
• and
• a focus control section which performs focus control by giving a focus driving signal to the actuator,
• wherein, when starting the focus control, the focus control section detects an amplitude of vertical deviation of the optical disc from an optical signal reflected from the disc, which is obtained by giving minute wobbling to the objective lens in the state where the disc is rotated, sets limit values for preventing the objective lens from colliding with the optical disc when the objective lens is shifted toward the optical disc, and performs focusing within a range defined by the limit values.