Servo parameter detection method and optical pickup device using the same

A servo parameter detection method comprising the steps of:

• outputting a command for changing a servo parameter from an optical pickup inspection device to an optical pickup device which performs recording and reproduction on an optical recording/reproduction medium by using laser light so that the servo parameter of the optical pickup device is changed successively;
• generating reproduction signals successively by a reproduction signal generation circuit of the optical pickup device, based on reflected light resulting when the laser light emitted from the optical pickup device by successively changing the servo parameter is reflected by a reference disc serving as a reference for adjustment of the servo parameter;
• based on the reproduction signal generated by the reproduction signal generation circuit for each of the servo parameters, determining jitter representing quality of the reproduction signal by the optical pickup inspection device;
• by the optical pickup inspection device, approximating a relationship between the servo parameters and the jitter values, respectively, with an approximating curve;
• by the optical pickup inspection device, calculating a correlation coefficient between approximate values in the approximating curve of the servo parameters and the jitter values and measured values;
• and
• by the optical pickup inspection device, on condition that the calculated correlation coefficient is equal to or lower than a specified value, outputting once again to the optical pickup device a command for changing the servo parameter and calculating a correlation coefficient between the approximate values and the measured values of the servo parameters and the jitter values, and on the other hand, on condition that the calculated correlation coefficient is over the specified value, detecting a servo parameter value corresponding to a best value of the jitter values as a servo parameter of the optical pickup device.