METHOD OF IDENTIFYING OPTICAL DISC

• US 20080205229A1
• Filed: 02/26/2007
• Published: 08/28/2008
• Est. Priority Date: 02/26/2007
• Status: Abandoned Application

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Huang, Cheng-Chi, LI, Yung-Chih
• Application Number:
  US11/678,625
• Publication Number:
  US 20080205229A1
• Time in Patent Office: Days
• US Class Current: 369/53.23
• CPC Class Codes: G11B 19/127 involving detection of the number of sides, e.g. single or double, or layers, e.g. for multiple recording or reproducing layers
• CPC Class Codes: G11B 2007/0006 adapted for scanning different types of carrier, e.g. CD & DVD
• CPC Class Codes: G11B 2007/0013 for carriers having multiple discrete layers
• CPC Class Codes: G11B 7/1275 Two or more lasers having different wavelengths

Abstract

A method of identifying an optical disc is disclosed. The method includes enabling an optical pick-up unit to emit a first laser beam having a first wavelength to the optical disc; controlling the optical pick-up unit to move a focus point of the first laser beam in a direction of thickness of the optical disc; obtaining a first focus error (FE) signal corresponding to the first laser beam; counting a first s-curve number corresponding to s-curve occurring in the first FE signal; and identifying the optical disc according to the first s-curve number.

Claims

1. A method of identifying an optical disc, comprising:

enabling an optical pick-up unit to emit a first laser beam having a first wavelength to the optical disc;

controlling the optical pick-up unit to move a focus point of the first laser beam in a direction of thickness of the optical disc;

obtaining a first focus error (FE) signal corresponding to the first laser beam;

counting a first s-curve number corresponding to s-curve occurring in the first FE signal; and

identifying the optical disc according to the first s-curve number.

2. The method of claim 1, wherein the first wavelength complies with a first optical disc specification, and the step of identifying the optical disc according to the first s-curve number further comprises:

measuring a first distance between adjacent s-curves occurring in the first FE signal when the first s-curve number is not smaller than two;

comparing the first distance and a first predetermined threshold value;

when the first distance is greater than the first predetermined threshold value, identifying the optical disc as a multi-layer disc complying with the first optical disc specification; and

when the first distance is not greater than the first predetermined threshold value, identifying the optical disc as a multi-layer disc complying with a second optical disc specification.

3. The method of claim 1, wherein the first wavelength complies with a first optical disc specification, and when the first s-curve number is equal to one, the step of identifying the optical disc further comprises:

enabling the optical pick-up unit to emit a second laser beam having a second wavelength to the optical disc;

controlling the optical pick-up unit to move a focus point of the second laser beam in a direction of thickness of the optical disc;

obtaining a second FE signal corresponding to the second laser beam;

counting a second s-curve number corresponding s-curves occurring in the second FE signal; and

identifying the optical disc according to the second s-curve number.

4. The method of claim 3, wherein the second wavelength complies with a second optical disc specification, and the step of identifying the optical disc according to the second s-curve number further comprises:

when the second s-curve number is equal to one, identifying the optical disc as a single-layer disc complying with the first optical disc specification or the second optical disc specification.

5. The method of claim 4 further comprising:

rotating the optical disc;

wherein the step of identifying the optical disc as the single-layer disc complying with the first optical disc specification or the second optical disc specification comprises;

enabling a focusing servo control;

obtaining a reference signal produced from a reflected laser beam sensed by the optical pick-up unit; and

determining whether the optical disc complies with the first optical disc specification or the second optical disc specification according to the reference signal.

6. The method of claim 5, wherein the step of determining whether the optical disc complies with the first optical disc specification or the second optical disc specification according to the reference signal comprises:

when a peak-to-peak voltage of the reference signal is greater than a predetermined voltage, determining that the optical disc complies with the first optical disc specification; and

when the peak-to-peak voltage of the reference signal is not greater than the predetermined voltage, determining that the optical disc complies with the second optical disc specification.

7. The method of claim 5, wherein the reference signal is an RFRP signal or a CRTP signal.

8. The method of claim 4 further comprising:

rotating the optical disc;

wherein the step of identifying the optical disc as the single-layer disc complying with the first optical disc specification or the second optical disc specification comprises;

enabling a focusing servo control and a tracking servo control, and moving the optical pick-up unit along a track on the optical disc;

obtaining a clock signal produced according to a reflected laser beam sensed by the optical pick-up unit; and

determining whether the optical disc complies with the first optical disc specification or the second optical disc specification according to the clock signal.

9. The method of claim 8, wherein the step of determining whether the optical disc complies with the first optical disc specification or the second optical disc specification according to the clock signal comprises:

when a frequency of the clock signal is higher than a predetermined frequency, determining that the optical disc complies with the first optical disc specification; and

when the frequency of the clock signal is not higher than the predetermined frequency, determining that the optical disc complies with the second optical disc specification.

10. The method of claim 8, wherein the clock signal is a data clock or a wobble clock.

11. The method of claim 3, wherein the second wavelength complies with a second optical disc specification, and the step of identifying the optical disc according to the second s-curve number further comprising:

measuring a second distance between adjacent s-curves occurring in the second FE signal when the second s-curve number is greater than one;

comparing the second distance and a second predetermined threshold value;

when the second distance is greater than the second predetermined threshold value, identifying the optical disc as a disc having recording layers complying with the first optical disc specification and the second optical disc specification respectively; and

when the second distance is not greater than the second predetermined threshold value, identifying the optical disc as a multi-layer disc complying with the second optical disc specification.

12. A method of identifying an optical disc, comprising:

enabling an optical pick-up unit to emit a laser beam to the optical disc;

enabling a focusing servo control;

obtaining a reference signal produced from a reflected laser beam sensed by the optical pick-up unit;

when a peak-to-peak voltage of the reference signal is greater than a predetermined voltage, determining that the optical disc complies with a first optical disc specification; and

when the peak-to-peak voltage of the reference signal is not greater than the predetermined voltage, determining that the optical disc complies with a second optical disc specification.

13. The method of claim 12, further comprising:

controlling the optical pick-up unit to move a focus point of the laser beam in a direction of thickness of the optical disc;

obtaining a focus error (FE) signal corresponding to the laser beam;

counting a s-curve number corresponding to s-curve occurring in the FE signal;

when the s-curve number is greater than one, and the optical disc complies with the first optical disc specification, identifying the optical disc as a multi-layer disc, otherwise identifying the optical disc as a single-layer disc; and

when the s-curve number is greater than one, and the optical disc complies with the second optical disc specification, identifying the optical disc as a multi-layer disc, otherwise identifying the optical disc as a single-layer disc.

14. The method of claim 12, wherein the reference signal is an RFRP signal or a CRTP signal.

15. A method of identifying an optical disc, comprising:

enabling an optical pick-up unit to emit a blue-ray laser beam to the optical disc;

enabling a focusing servo control and a tracking servo control, and moving the optical pick-up unit along a track on the optical disc;

obtaining a clock signal produced according to a reflected laser beam sensed by the optical pick-up unit;

when a frequency of the clock signal is lower than a predetermined frequency, determining that the optical disc complies with the first optical disc specification; and

when the frequency of the clock signal is higher than the predetermined frequency, determining that the optical disc complies with the second optical disc specification.

16. The method of claim 15, wherein the clock signal is a data clock or a wobble clock.