Drop-out detection circuit

Abstract

A drop-out detection circuit which supplies an output signal indicative of a drop-out within information reproduced from a storage medium, when a rectangular wave signal produced from a modulated signal carrying the reproduced information does not supply a trigger pulse within a prescribed pulse duration. The drop-out detection circuit comprises a first pulse generation part for supplying a first pulse signal having a low level for a prescribed pulse duration when the rectangular wave signal changes from a low level to a high level, a second pulse generation part for supplying a second pulse signal having a low level for the prescribed pulse duration when the rectangular wave signal changes from the high level to the low level, and a logic gate for outputting the output signal having a high-level pulse supplied only when the first pulse signal and the second pulse signal both having the high level is supplied for a time period exceeding the prescribed pulse duration. The drop-out detection circuit can detect the drop-out within the reproduced information accurately, without being affected by a change in the ambient temperature and a fluctuation of the frequency of the modulated signal.