Method for accurate positioning of data marks and spaces on an optical disc

• US 6,631,108 B1
• Filed: 04/03/2000
• Issued: 10/07/2003
• Est. Priority Date: 04/03/2000
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Hogan, Josh
• Primary Examiner(s): Korzuch, William
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US09/542,404
• Time in Patent Office: 1,282 Days
• Field of Search: 369/59.11, 369/59.12, 369/47.3, 369/47.17, 369/44.26, 369/106, 369/275.4, 369/30.21, 369/53.35, 369/53.36
• US Class Current: 369/53.35
• CPC Class Codes: G11B 7/00456 Recording strategies, e.g. pulse sequences G11B7/0062 takes precedence

Abstract

An optical disc has spatial features (notches, bumps, etc.) that intentionally distort the analog Read Data signal. For a mark or space that is centered on a spatial feature, the distortion does not affect the resulting binary Read Data signal. If an edge of a mark or space is near the spatial feature, the resulting binary Read Data signal is altered. For calibration, marks or spaces are written adjacent to spatial features, with a range of times for initiating the writes. The result is a range of write times that do not alter the binary Read Data signal. From these known times and spatial locations, it is known when a mark or space must be written to ensure accurate spatial placement.

Claims

1. A method, comprising:

writing a first data set, with a write timing, at an area on an optical disc that has spatial features that distort an analog read data signal, the distortion varying as a function of write timing;

writing a second data set, with the write timing, at an area on the optical disc that has spatial features that distort an analog read data signal, the distortion varying as a function of write timing;

reading the first data set and the second data set from the optical disc;

determining a first read error rate for the first data set, and a second read error rate for the second data set, wherein at a particular write timing, the first and second read error rates are expected to be non-zero and equal, and for any write timing other than the particular write timing, the first and second read error rates are expected to be unequal;

comparing the first and second error rates; and

adjusting the write timing based on the comparison of the first and second error rates.

2. The method of claim 1, wherein for a shift of the write timing in a first direction, the first read error rate is expected to increase and the second read error rate is expected to decrease, and for a shift of the write timing in a direction that is opposite the first direction, the first read error rate is expected to decrease and the second read error rate is expected to increase.

3. A method, comprising:

writing a first data set, with a write timing, at an area on an optical disc that has spatial features that distort an analog read data signal, the distortion varying as a function of write timing;

writing a second data set, with the write timing, at an area on the optical disc that has spatial features that distort an analog read data signal, the distortion varying as a function of write timing;

writing a third data set, with the write timing, at an area on the optical disc that has spatial features that distort an analog read data signal, the distortion varying as a function of write timing;

reading the first data set, the second data set, and the third data set from the optical disc;

determining a first read error rate for the first data set, a second read error rate for the second data set, and a third error rate for the third data set;

comparing the first, second, and third error rates; and

adjusting the write timing based on the comparison of the first, second, and third error rates.

4. The method of claim 3, wherein at a particular write timing, the first and second read error rates are expected to be non-zero and equal, and the third read error rate is expected to be zero, and for any write timing other than the particular write timing, the first and second read error rates are expected to be unequal and the third read error rate is expected to be nonzero.

5. The method of claim 4, wherein for a shift of the write timing in a first direction, the first read error rate is expected to increase and the second read error rate is expected to decrease, and for a shift of the write timing in a direction that is opposite the first direction, the first read error rate is expected to decrease and the second read error rate is expected to increase.