Dropout detection circuit and optical disc apparatus

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.

Dependencies are inferred from the claim text.