Evaluation signal generating device, focus bias adjustment method, skew adjustment method

摘要

PROBLEM TO BE SOLVED: To perform a correct signal evaluation with a simple constitution by detecting phase error information from a readout data signal, obtaing an evaluation signal while making the absolute value of this information an analog signal and performing the quality evaluation of the signal while performing the A/D conversion of the evaluation signal. ;SOLUTION: A readout EMF signal from a binary circuit 25 is supplied to a PLL circuit and a reproducing clock PLCK synchronized with the EMF signal is generated to be supplied to necessary respective parts. Moreover, the EFM signal is also supplied to an evaluation signal generating circuit 35 and an evaluation signal HS is generated from the EFM signal and the reproducing clock PLCK in the circuit 35. This signal HS makes the phase error information between the EMF signal and the reproducing clock PLCK an absolute value and also an analog signal. The signal HS is supplied to the A/D conversion input port of a system controller and is made to be a digital value to be fetched in the controller. As a result, the controller can make the evaluation signal HS the scale of the quality evaluation of the signal. Thus, the correct quality evaluation of the reproduced signal is performed by a simple circuit constitution.;COPYRIGHT: (C)1998,JPO