OPTICAL DISC APPARATUS, FOCUS ERROR SIGNAL ADJUSTMENT METHOD, PROGRAM, AND INTEGRATED CIRCUIT

摘要

To adjust the symmetry of a focus error signal, the symmetry of the focus error signal needs to be measured during upward and downward driving of an objective lens, which is performed at every varying setting of a signal correction gain value of the focus error signal, and such adjustment takes a long time. An optical disc device (100) measures a focus error signal before differentiation at a local maximum point and a local minimum point of a focus error signal using a prior-to-differentiation FE measurement unit (50), and calculates the symmetry of the S-shape of a focus error signal using a symmetry calculation unit (51), and performs balance adjustment based on the calculation result. The device with this structure adjusts the symmetry of a focus error signal at a high speed by requiring an upward and downward operation to be performed only once.