Optical disk device and method of adjusting tilt control amount

An optical disk device comprising:

• an optical pickup that writes information on an optical disk, or reproduces information from the optical disk, the optical disk being attached to the optical disk device;
• a tilt sensor that is provided on the optical pickup, and detects inclination of the optical disk;
• a tilt detection circuit that detects an output of the tilt sensor;
• an objective lens that is provided on the optical pickup, and focuses laser light on the optical disk;
• tilt driving means for inclining the objective lens by an amount corresponding to a driving signal in terms of a radial direction of the optical disk;
• a tilt driving circuit that applies the driving signal to the tilt driving means, based on a control signal;
• and
• tilt control means for providing the control signal to the tilt driving circuit, based on an output of the tilt detection circuit,
• wherein a reference output of the tilt detection circuit is set as a reference tilt detection value, the reference output being based on an inner side radial position of a reference optical disk having a warping amount that changes from the inner side radial position to an outer side radial position of the reference optical disk.
• a reference control signal is set as a reference control value, the reference control signal corresponding to a reference driving inclining amount in which inclining the objective lens by the reference driving inclining amount minimizes or reduces inclination of the objective lens relative to the reference optical disk at the inner side radial position,
• a second reference output of the tilt detection circuit is set as a second reference tilt detection value, the second reference output being based on the outer side radial position of the reference optical disk,
• a second reference control signal is set as a second reference control value, the second reference control signal corresponding to a second reference driving inclining amount in which inclining the objective lens by the second reference driving inclining amount minimizes or reduces inclination of the objective lens relative to the reference optical disk at the outer side radial position,
• the optical disk device further comprises tilt relation storing means for storing the reference tilt value, the second reference tilt value, the reference control value and the second reference control value, or storing constants that represent relation between the output of the tilt detection circuit and the control signal, the constants being calculated based on the reference tilt value, the second reference tilt value, the reference control value and the second reference control value,
• and the tilt control means calculate the control signal based on the output of the tilt detection circuit by using the information stored in the tilt relation storing means.

A method of performing tilt adjustment of an objective lens relative to an optical disk, comprising the steps of:

• attaching to an optical disk device a reference optical disk in which a warping amount of the reference optical disk is equal to or smaller than a predetermined value;
• detecting a reference inclination amount of the reference optical disk in terms of a radial direction of the reference optical disk;
• obtaining a reference driving inclining amount in which inclining the objective lens by the reference driving inclining amount minimizes or reduces inclination of the objective lens relative to the reference optical disk;
• storing the reference inclination amount as a reference tilt value, and storing the reference driving inclining amount as a reference control value;
• removing the reference optical disk from and attaching an object optical disk to the optical disk device;
• detecting an object inclination amount of the object optical disk;
• determining a target inclining amount based on the reference tilt value, the reference control value, and the object inclination amount;
• and
• inclining the objective lens by the target inclining amount to perform tilt adjustment of the objective lens relative to the object optical disk.

A method of performing tilt adjustment of an objective lens relative to an optical disk, comprising the steps of:

• attaching to an optical disk device a reference optical disk in which a warping amount of the reference optical disk changes from an inner side to an outer side of the reference optical disk;
• detecting a reference inclination amount of the reference optical disk at the inner side in terms of a radial direction of the reference optical disk;
• obtaining a reference driving inclining amount in which inclining the objective lens by the reference driving inclining amount minimizes or reduces inclination of the objective lens relative to the reference optical disk at the inner side;
• detecting a second reference inclination amount of the reference optical disk at the outer side in terms of the radial direction of the reference optical disk;
• obtaining a second reference driving inclining amount in which inclining the objective lens by the second reference driving inclining amount minimizes or reduces inclination of the objective lens relative to the reference optical disk at the outer side;
• removing the reference optical disk from and attaching an object optical disk to the optical disk device;
• detecting an object inclination amount of the object optical disk;
• determining a target inclining amount based on the object inclination amount, the reference inclination amount, the second reference inclination amount, the reference driving inclining amount, and the second reference driving inclining amount;
• and
• inclining the objective lens by the target inclining amount to perform tilt adjustment of the objective lens relative to the object optical disk.

An optical disk device, comprising:

• an optical pickup that records information on an optical disk or reproduces information from the optical disk;
• a tilt sensor that detects inclination of the optical disk in terms of a radial direction of the optical disk;
• an objective lens supported by the optical pickup to perform said information recording and reproducing;
• a tilt adjustment mechanism for inclining the objective lens in terms of the radial direction based a driving signal;
• a tilt driving circuit that applies the driving signal to the tilt adjustment mechanism based on a control signal;
• a tilt detection circuit that generates a tilt detection result based on the inclination detected by the tilt sensor, wherein the tilt detection result constitutes a reference tilt value when the optical disk is a reference optical disk having a warping amount equal to or smaller than a predetermined value, and wherein the tilt detection result constitutes an object inclination amount when the optical disk is an object optical disk;
• a memory that stores the reference tilt value;
• a CPU for providing the control signal to the tilt driving circuit, wherein the control signal for adjusting relative inclination between the objective lens and the object optical disk is determined by:
• Y=k×(X−X0)
• wherein Y is the control signal, X is the object inclination amount, X0 is the reference tilt value, and k is a predetermined control constant.

An optical disk device, comprising:

• an optical pickup that records information on an optical disk or reproduces information from the optical disk;
• a tilt sensor that is provided on the optical pickup and detects inclination of the optical disk in terms of a radial direction of the optical disk;
• a tilt detection circuit that detects an output of the tilt sensor;
• an objective lens that is provided on the optical pickup for information recording or reproducing;
• tilt driving means for inclining the objective lens in terms of the radial direction, based on a driving signal;
• a tilt driving circuit that applies the driving signal to the tilt driving means based on a control signal;
• tilt control means for providing the control signal to the tilt driving circuit based on an output of the tilt detection circuit;
• reference tilt value storing means for storing a reference output of the tilt detection circuit as a reference tilt value, the reference output of the tilt detection circuit being based on a reference optical disk having a warping amount equal to or smaller than a predetermined value;
• reference control value storing means for storing as a reference control value a reference control signal corresponding to a reference driving inclining amount in which inclining the objective lens by the reference driving inclining amount reduces inclination of the objective lens relative to the reference optical disk;
• wherein the tilt control means is adapted to determine, for adjusting inclination of the objective lens relative to an object optical disk, a target inclining amount by which the objective lens may be tilted relative to the object optical disk, and wherein the target inclining amount is based on the reference tilt value, the reference control value, and an object output of the tilt detection circuit corresponding to the object optical disk.