Dropout detection circuit and optical disc apparatus
US7567488B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 2006 |
| Grant date | Jul 28, 2009 |
| Priority date | — |
| Expiry date | Aug 22, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0948
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The dropout detection circuit of the invention includes: a high-speed envelope detection circuit for detecting an envelope of a reflection signal of a light beam with a first time constant; a low-speed envelope detection circuit for detecting an envelope of the reflection signal with a second time constant larger than the first time constant; a differential circuit for generating a difference signal indicating the difference between the envelopes detected by the envelope detection circuits; and a comparator for converting the difference signal to a binary value according to a predetermined binary criterion. The high-speed envelope detection circuit makes the first time constant larger during recording than during reproduction, to enable stable dropout detection irrespective of during reproduction or during recording.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.