Differential phase error detector using dual arm correlation for servo tracking in an optical disk storage device
US5956304A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1997 |
| Grant date | Sep 21, 1999 |
| Priority date | — |
| Expiry date | Aug 15, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0901
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an optical disk storage device, a differential phase detector is disclosed for generating a position error signal independent of the frequency content of the recorded data. A pair if diagonal signals S1 and S2 are generated by adding a pair of respective quadrants of a four-quadrant photodetector, where the phase offset between the diagonal signals represents the position error of the pit image as it passes over the photodetector. The position error is determined in the present invention by computing the difference between a positive and negative correlation of the diagonal signals S1 and S2, otherwise referred to as a dual arm correlation (DAC) ##EQU1## where .DELTA. is the correlation offset and L is the correlation length. In the preferred embodiment, the correlation offset .DELTA. is adaptively adjusted to maximize the correlation between S1 and S2. In this manner, the position error estimate is substantially insensitive to the frequency content of the recorded data. Furthermore, this method extends the position error over a range of plus or minus one-half a track, which facilitates generating a quadrature signal for use in counting track crossings during seek operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.