Optical head, disc recording/reproducing apparatus, and objective lens drive method

An optical head comprising:

• a light source, an objective lens for converging a light beam from the light source on a recording surface of a disc-shape recording medium, an objective lens drive portion for driving the objective lens in a radial direction and in a focus direction of the disc-shape recording medium by applying a drive current to a coil attached to the objective lens, a first light-receiving portion and a second light-receiving portion for receiving light reflected by the recording surface of the disc-shape recording medium and converting the reflected light into an electric signal, a signal generation portion for generating a focus error signal from the electric signal converted at the first light-receiving portion and generating a tracking error signal from the electric signal converted at the second light-receiving portion, and a control portion for controlling the objective lens drive portion, on the basis of the focus error signal and the tracking error signal;
• wherein
• the control portion calculates a defocus amount corresponding to a level of the drive current applied by the objective lens drive portion so as to shift the objective lens in the radial direction, generates an offset signal based on the calculated defocus amount, and applies the generated offset signal to the focus error signal so as to control the objective lens drive portion.

(CANCELED)

An optical head comprising:

• a light source, an objective lens for converging a light beam from the light source on a recording surface of a disc-shape recording medium, an objective lens drive portion for driving the objective lens in a radial direction and in a focus direction of the disc-shape recording medium, a first light-receiving portion and a second light-receiving portion for receiving light reflected by the recording surface of the disc-shape recording medium and converting the reflected light into electric signals, a signal generation portion for generating a focus error signal from the electric signal converted at the first light-receiving portion and generating a tracking error signal from the electric signal converted at the second light-receiving portion, and a control portion for controlling the objective lens drive portion based on the focus error signal and the tracking error signal;
• wherein
• the control portion calculates an off-track amount corresponding to the shift amount in the radial direction of the objective lens due to the objective lens drive portion, generates an offset signal based on the calculated off-track amount, and applies the generated offset signal to the tracking error signal so as to control the objective lens drive portion.

A disk recording/reproducing apparatus comprising at least the optical head according to claim and a feeder for feeding the optical head in the radial direction of the disc-shape recording medium, wherein

• the feeder comprises at least a feed screw that fits the optical head so as to shift the optical head in the radial direction and a drive motor for rotating the feed screw, and the feeder is configured so that the drive motor rotates to feed the optical head when the shift in the radial direction of the objective lens due to the objective lens drive portion exceeds a certain value, and
• the feed amount of the optical head due to the feeder differs between a time of recording and a time of reproduction.

(CANCELED)

(CANCELED)