Optical disk apparatus and method of recording with optical disk apparatus

• US 20050162998A1
• Filed: 01/26/2005
• Published: 07/28/2005
• Est. Priority Date: 01/27/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Shinji, Iwasaki, Satoshi, Fujishima, Hideyuki
• Granted Patent: US 7,570,552 B2
• Time in Patent Office: Days
• US Class Current: 369/44.320
• CPC Class Codes: G11B 7/0945 Methods for initialising servos, start-up sequences
• CPC Class Codes: G11B 7/0956 to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc

Abstract

During recording with an optical disk apparatus, an objective lens is moved toward the inner circumference and outer circumference of an optical disk in the radial direction thereof and also moved upward and downward, and the quantity of reflected light is measured at that time. Quantities of reflected light are determined taking advantage of the characteristic of laser heat that it is most efficiently used to provide the smallest quantity of reflected light when the relationship between the optical disk surface and the objective lens is closest to perpendicularity and when they are at a distance at which the point in focus is most closely approached. An optimum tilt value and focus position are learned from the result of the determination to allow operations to be performed at the optimum tilt and the optimum position of the point in focus.

Claims

1. An optical disk apparatus for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising:

a light-receiving unit for receiving reflected light from an optical disk under recording;

a calculation unit for performing a calculation on the received signal;

a signal detection unit for detecting the received signal;

an A-D conversion unit for performing A-D conversion of the detected signal;

a calculation/comparison unit for performing a calculation and a comparison on the A-D-converted signal;

a thermal efficiency detection unit for detecting a change in the thermal efficiency of laser power for recording from the result of the calculation at the calculation/comparison unit;

a focus control unit performing at least either of control in which the quantity of a tilt of the objective lens of the optical pickup relative to the radial direction of the optical disk is calculated from the result of the detection by the thermal efficiency detection unit and in which the objective lens is tilted by the quantity of tilt obtained by the calculation to adjust the distance thereof from the optical disk and control in which the quantity of a focus offset of the objective lens of the optical pickup relative to the radial direction of the optical disk and is calculated from the result of the detection by the thermal efficiency detection unit and in which the objective lens is moved upward or downward by the quantity of focus offset obtained by the calculation to adjust the distance thereof from the optical disk; and

a focus coil drive unit for driving a focus coil to operate the objective lens based on a signal output y the focus control unit.

3. An optical disk apparatus according to claim 1, wherein the objective lens is tilted in the radial direction of the disk using the focus control unit.

4. An optical disk apparatus according to claim 1, wherein reflected light from the optical disk under recording is received by the light-receiving unit and wherein a change in the thermal efficiency of laser power during recording is detected from a change in the reflected light.

5. An optical disk apparatus according to claim 1, wherein the objected lens is tilted from the current state toward the outer circumference and inner circumference of the optical disk in the radial direction thereof during recording and wherein the quantity of a tilt of the optical axis of the laser relative to a surface of the optical disk is obtained from a change in reflected light at that time.

6. An optical disk apparatus according to claim 1, wherein the measurement of a change in reflected light during recording is performed by measuring reflected light within one turn of the optical disk to prevent misdetection of the reflected light attributable to a runout component of the optical disk.

7. An optical disk apparatus according to claim 1, wherein a change in reflected light from the optical disk under recording is detected and in which the quantity of a tilt of the objective lens relative to the radial direction of the optical disk is controlled such that the optical disk and the optical axis of the laser are in a substantially perpendicular relationship.

8. An optical disk apparatus according to claim 1, wherein a process of operating the objective lens to make optical disk and the optical axis of the laser closest to perpendicularity during recording is performed during a recording operation.

9. An optical disk apparatus according to claim 1, wherein the objective lens is moved from a predetermined state upward and downward relative to a surface of the optical disk during recording to obtain the distance between the surface of the optical disk and the objective lens from a change in reflected light during recording at that time.

10. An optical disk apparatus according to claim 1, wherein a change in reflected light from the optical disk under recording is detected to control the distance between the optical disk and the objective lens such that it substantially equals the focal length.

11. An optical disk apparatus according to claim 1, wherein a process of making the distance between the optical disk and the objective lens substantially equal to the focal length during recording is performed during a recording operation.

12. An optical disk apparatus according to claim 1, wherein a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length are performed during recording at each predetermined interval in the radial direction of the optical disk.

13. An optical disk apparatus according to claim 1, wherein when a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length are performed during recording, the value of a tilt associated with a position of the disk in the radial direction thereof and the temperature at that time are simultaneously acquired and stored in the form of a table.

14. An optical disk apparatus according to claim 1, wherein selection can be made on whether to perform a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length at each predetermined interval in the radial direction of the disk.

15. An optical disk apparatus according to claim 1, wherein a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length are performed during recording and wherein the result of the processes in the form of a table showing the value of a tilt and a temperature associated with a position of the disk in the radial direction thereof or the result of tilt value acquisition at the time of activation is selected when the optical disk apparatus performs a reproduction operation or an additional write operation depending on the temperature at that time.

16. An optical disk apparatus according to claim 1, wherein a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length during recording are performed only in a data recording area of the optical disk by referring to a table for storing information on whether to permit or inhibit the process of tilting the objective lens relative to a position of the optical disk in the radial direction thereof so as to make the optical axis of the laser substantially perpendicular to the optical disk.

17. An optical disk apparatus according to claim 1, the optical disk apparatus using a result obtained during recording by a process of making the distance between the optical disk and the objective lens substantially equal to the focal length when it starts a reproduction operation after finishing the recording.

2. An optical disk apparatus for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising:

a light-receiving unit for receiving reflected light from an optical disk under recording;

a calculation unit for performing a calculation on the received signal;

a signal detection unit for detecting the received signal;

an A-D conversion unit for performing A-D conversion of the detected signal;

a calculation/comparison unit for performing a calculation and a comparison on the A-D-converted signal;

a reflected light quantity detection unit for detecting a change in the quantity of reflected light from the result of the calculation at the calculation/comparison unit;

a focus control unit performing at least either of control in which the quantity of a tilt of the objective lens of the optical pickup relative to the radial direction of the optical disk is calculated from the result of the detection by the reflected light quantity detection unit and in which the objective lens is tilted by the quantity of tilt obtained by the calculation to adjust the distance thereof from the optical disk and control in which the quantity of a focus offset of the objective lens of the optical pickup relative to the radial direction of the optical disk and is calculated from the result of the detection by the reflected light quantity detection unit and in which the objective lens is moved upward or downward by the quantity of focus offset obtained by the calculation to adjust the distance thereof from the optical disk; and

a focus coil drive unit for driving a focus coil to operate the objective lens based on a signal output y the focus control unit.

18. An optical disk recording method for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising the steps of:

changing the optical axis of the laser relative to the optical disk and detecting reflected light from the optical disk during recording;

obtaining the quantity of a tilt of the optical axis of the laser relative to a surface of the optical disk from a change in the reflected light; and

adjusting the quantity of tilt to a predetermined quantity.

22. A method of recording with an optical disk apparatus according to claim 18, wherein when a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length are performed during recording, the value of a tilt associated with a position of the disk in the radial direction thereof and the temperature at that time are simultaneously acquired and stored in the form of a table.

23. A method of recording with an optical disk apparatus according to claim 18, comprising the steps of:

performing a process of tilting the objective lens so as to make the optical axis of the laser substantially perpendicular to the optical disk and a process of making the distance between the optical disk and the objective lens substantially equal to the focal length are performed during recording; and

selecting either of the result of the processes in the form of a table showing the value of a tilt and a temperature associated with a position of the disk in the radial direction thereof or a tilt value associated with the position of the optical disk in the radial direction thereof acquired at the time of activation when the optical disk apparatus performs a reproduction operation or an additional write operation depending on the temperature at that time.

19. An optical disk recording method for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising the steps of:

detecting a change in reflected light from the optical disk during recording; and

controlling the quantity of a tilt of an objective lens relative to the optical disk during recording such that the optical disk and the optical axis of the laser are in a substantially perpendicular relationship.

20. An optical disk recording method for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising the steps of:

moving an objective lens from a predetermined state upward and downward relative to a surface of the optical disk during recording to obtain the distance between the surface of the optical disk and the objective lens from a change in reflected light during recording at that time; and

adjusting the distance to a predetermined quantity.

21. An optical disk recording method for recording data on a recordable type optical disk utilizing a pattern of emission of a laser, comprising the steps of:

moving an objective lens from a predetermined state upward and downward relative to a surface of the optical disk during recording; and

controlling the distance between the optical disk and the objective lens so as to make it substantially equal to the focal length based on a change in reflected light during recording at that time.