Differential track recording
US4706235A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 25, 1985 |
| Grant date | Nov 10, 1987 |
| Priority date | — |
| Expiry date | Jan 25, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/004
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus and methods are disclosed for writing data on a track in an optical disk data storage device wherein the track is divided into two parts and binary one bits are written into one part of the data track while binary zero bits are written into the second part of the data track. Detection of data written in this manner is performed using two read coherent radiation beams each positioned over one of the parts of the data track. A binary one is detected if the signal from the beam over the first part of the data track is greater than the signal from the beam over the second part of the data track, and a binary zero is indicated if the signal from the beam over the second part of the data track is greater than the signal of the beam over the first part of the data track. In order to detect the data from the two read beams, they must be aligned accurately over the two halves of the data track. To aid this alignment, a third larger beam is used to measure the total energy from the data track. If the beams are not aligned correctly over the track, the signal output from the large beam will exceed the sum of the signal outputs from the two smaller read beams indicating the offtrack …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.