Patent ID: 7639579

Claim:
A white dot out detecting device comprising: a recording/reproduction control signal generator for generating a recording/reproduction control signal showing a recording state or a reproducing state of an optical disk; a variable gain amplifier for amplifying and outputting an information signal read from the optical disk and adjusting a gain in the amplification based on the recording/reproduction control signal; an envelope detector for detecting an output envelope of the variable gain amplifier; an integrator for integrating an output of the envelope detector; a slice level setting unit for setting a slice level as a reference for detecting a white dot out based on an output of the integrator; a comparator for detecting the white dot out based on comparison of the output of the envelope detector and the slice level to each other; a level shifter for temporarily shifting the slice level to a high-level side when a change of the recording/reproduction control signal showing change of status from the recording state to the reproducing state or the reproducing states to the recording state is detected; a limiter for limiting the output of the envelope detector to stay within an input-side dynamic range of the comparator; and a limiter for limiting the output of the slice level setting unit to stay within the input-side dynamic range.