Method and apparatus for laser power control during recording

• US 20020136121A1
• Filed: 03/26/2001
• Published: 09/26/2002
• Est. Priority Date: 03/26/2001
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: Zoran Corporation (Qualcomm, Inc.)
• Inventors: Kelly, John, Salmonsen, Daniel
• Granted Patent: US 6,636,468 B2
• Time in Patent Office: Days
• US Class Current: 369/47.53
• CPC Class Codes: G11B 7/00458 Verification, i.e. checking data during or after recording
• CPC Class Codes: G11B 7/1267 Power calibration

Abstract

A method comprises writing data to a disk using a write laser, and halting recording at a stopping point, prior to an end of the disk. The method further comprises reading the data recorded on the disk and evaluating the data. The method further comprises adjusting the characteristics of the write laser, if appropriate, and restarting the writing using the adjusted characteristics for the write laser.

Claims

1. A method comprising:

writing data to a disk using a write laser;

halting recording at a stopping point, prior to an end of the disk;

reading the data recorded on the disk;

evaluating the data, and adjusting the characteristics of the write laser, if appropriate; and

restarting the writing using the adjusted characteristics for the write laser.

2. The method of claim 1, wherein the characteristics comprise a power level of the write laser.

3. The method of claim 1, wherein the characteristics comprise a pulse shape written by the write laser.

4. The method of claim 1, wherein the evaluation comprises detecting one or more of the following characteristics of the data that was written:

error rate, symmetry, and jitter.

5. The method of claim 1, wherein adjusting the characteristics compensates for one or more of the following:

changes in tangential velocity, media coating, operating temperature of a laser diode or media, track radius, elapsed time since the characteristics were initially set, tilt, focus, and radial or vertical runout.

6. The method of claim 1, wherein halting the recording comprises:

reaching an evaluation point;

receiving a pre-programmed stopping point from a stopping logic; and

stopping at the pre-programmed stopping point.

7. The method of claim 6, wherein restarting the recording comprises:

receiving a pre-programmed starting point from the stopping logic; and

starting at the pre-programmed starting point.

8. The method of claim 7, wherein the pre-programmed starting point is before the pre-programmed stopping point.

9. The method of claim 1, wherein recording is stopped periodically.

10. The method of claim 9, wherein recording is stopped when a timer has elapsed.

11. The method of claim 9, wherein recording is stopped when a preset amount of data has been recorded.

12. The method of claim 9, wherein recording is stopped at random times during the recording process.

13. The method of claim 9, wherein the recording is stopped when a change in a writing speed is detected.

14. The method of claim 9, wherein the recording is stopped when a temperature sensor indicates a sufficient change in temperature to affect the writing process.

15. The method of claim 9, wherein the recording is stopped when writing is changed from CAV to CLV.

16. The method of claim 9, wherein the recording is stopped, in a packet-type writing, at an end of a packet.

17. The method of claim 9, wherein the recording is stopped when a running optimum power control (ROPC) logic detects a sufficient difference between an optimum power control (OPC) period and the signals when the data is being written.

18. The method of claim 9, wherein the recording is stopped during a beginning of recording, to verify a result of an optimum power control (OPC) adjustment.

19. The method of claim 1, wherein the recording is stopped and restarted at least three times during an entire recording session.

20. The method of claim 1, wherein the compact disk is not a multi-session disk, and traditional compact disk readers are able to read the compact disk.

21. An apparatus comprising:

a stopping logic to halt recording to a disk at a stopping point, prior to an end of the disk;

a read data analysis logic to read the data recorded on the disk and to evaluate the data; and

a laser adjust logic to adjust the characteristics of the write laser, if appropriate.

22. The apparatus of claim 21, wherein the characteristics comprise a power level of the write laser.

23. The apparatus of claim 21, wherein the characteristics comprise a pulse shape written by the write laser.

24. The apparatus of claim 21, wherein the read data analysis logic is further to detect one or more of the following characteristics of the data that was written:

error rate, symmetry, and jitter.

25. The apparatus of claim 21, wherein adjusting the characteristics compensates for one or more of the following:

changes in tangential velocity, media coating, operating temperature of a laser diode or media, track radius, and elapsed time since the characteristics were initially set.

26. The apparatus of claim 21, further comprising a trigger, the trigger to generate a stopping point, to stop the recording.

27. The apparatus of claim 26, wherein the trigger is a timer.

28. The apparatus of claim 27, wherein the timer stops the recording periodically.

29. The apparatus of claim 26, wherein the trigger is a temperature sensor to generate the stopping point when a temperature change of a sufficient degree occurs.

30. The apparatus of claim 26, wherein the trigger is a writing speed difference detector to generate the stopping point when a writing speed has changed by a sufficient amount.

31. The apparatus of claim 26, wherein the trigger is a CAV/CLV change logic to generate the stopping point when a recording mode is changed.

32. The apparatus of claim 26, wherein the trigger is an initial analysis logic, the initial analysis logic to generate the stopping point a short time after the recording is started, to verify that a the changed laser characteristics are appropriate.

33. The apparatus of claim 26, wherein the trigger is a running optimum power control logic to monitor a reflection of the laser during the write process, and to generate the stopping point if a characteristic of the laser has changed by a sufficient amount.

34. The apparatus of claim 26, wherein the recording is stopped, in a packet-type writing, at an end of a packet.

35. The apparatus of claim 21, wherein the recording is stopped and restarted at least three times during an entire recording session.

36. The apparatus of claim 21, wherein the compact disk is not a multi-session disk, and traditional compact disk readers are able to read the compact disk.

38. The apparatus of claim 37, further comprising:

an optimal power control logic to set characteristics of the write laser in a power calibration area of the disk for writing data to the disk prior to initially writing data to the disk.

39. The apparatus of claim 37, wherein the characteristics comprise a power level of the write laser.

40. The apparatus of claim 37, wherein the characteristics comprise a pulse shape written by the write laser.

41. The apparatus of claim 37, further comprising:

a stop logic to receiving a pre-programmed stopping point when triggered by the stopping logic, the stop logic to halt recording at the preprogrammed stopping point.

42. The apparatus of claim 41, further comprising:

a start logic to receive a pre-programmed starting point when triggered by the laser adjust logic, the start logic further to start recording at the preprogrammed starting point.

43. The apparatus of claim 42, wherein the pre-programmed starting point is before the pre-programmed stopping point.

44. The apparatus of claim 37, further comprising a trigger to generate a stop point for the stopping logic.

37. An apparatus comprising:

a write logic to write data to a disk using a write laser;

a stopping logic to halt recording at a stopping point, prior to an end of the disk;

a read logic to read the data recorded on the disk;

a read data analysis logic to evaluate the data;

a laser adjust logic to alter the characteristics of the write laser, if appropriate; and

the write logic to restarting the writing using the adjusted characteristics for the write laser.