Patent ID: 7463567
Filing Date: 2008-12-09
Classification: G11B

Abstract:
1. An optical disc recording/reproducing apparatus comprising: a control unit which, when an optical disc has been inserted, executes reading of information recorded on said optical disc; a motor for rotating said optical disc at a predetermined rotation speed in response to commands from said control unit; an information reading part for applying light to said optical disc in response to commands from said control unit and, also, receiving reflected light from pits recorded on said optical disc to output signals based on said recorded pits; and a determination part for determining the condition of recording of said optical disc on the basis of signals output from said information reading part, wherein said information reading part includes: an optical pickup for applying light to said optical disc and, also, receiving reflected light from pits recorded on said optical disc to convert the reflected light into electrical signals and, then, output the electrical signals; a signal processing unit for subjecting electrical signals from said optical pickup to signal processing to generate RF signals; a data slice signal generation unit for processing said RF signals to generate data slice signals; and a focusing control unit for performing focus-on of light to be applied such that the focus point of the light is positioned on the surface of said optical disc, said determination part determines the condition of recording of said optical disc on the basis of the detection period of signals from longest pits recorded on said optical disc, wherein the period is changed with the acceleration of the rotation of said optical disc until said predetermined rotation speed is achieved, said determination part includes: a pulse-width counter for measuring the pulse widths of said data slice signals; a maximum-value detection circuit for detecting the maximum pulse-width value of said longest pits measured by said pulse-width counter; and a determination circuit for calculating the detection period of the maximum values detected by said maximum-value detection circuit and for determining the condition of recording of said optical disc on the basis of the change of the detection period of said maximum values, and said determination circuit determines that said optical disc is a recorded disc when the detection period of the maximum values detected by said maximum-value detection circuit is shortened with the acceleration of the rotation of said optical disc.