Patent ID: 7212472

Claim:
A focus jump method, of an optical disc apparatus having a focus jump function for enabling a focus control of an objective lens for focusing laser light on each of a plurality of recording layers of a disc, for changing focusing of the objective lens from a first recording layer to a second recording layer by moving the objective lens, the focus jump method comprising: generating a focus error signal based on light reflection from a recording layer of the disc; generating a differentiation signal by differentiating the focus error signal; and moving the objective lens from a state of focusing on a first recording layer to a state of focusing on a second recording layer, wherein: the moving of the objective lens includes using the differentiation signal to move the objective lens over a section of the focus jump from a time point F to a time point G; the time point F is when level of the focus error signal becomes lower or higher than a threshold level, after the focus error signal has been zero following a time when the focus error signal has once been a maximum value or a minimum value; and the time point G is when the focus error signal has a minimum value or maximum value after the time point F.