Patent ID: 6865145

Claim:
A recoding-medium operating device for data operation to a recording medium, the recording-medium operating device comprising: a clock outputting circuit that outputs a plurality of clock signals that have same frequency but differ in phase one another, based on phase-information mark formed on a recording medium beforehand; a first selector that selects one of the plurality of the clock signals outputted from the clock outputting circuit; a delay circuit that receives an input of an clock signal selected by the first selector and has multi-level of delay quantity; a second selector that selects a delay quantity at the delay circuit; a phase-difference detecting section that detects phase difference between a signal reproduced from a data region on a recording medium and a clock signal; and a controlling section that controls selection by the first selector and selection by the second selector, wherein phase difference between delay quantities of the delay circuit is smaller than phase difference between clock signals of the clock outputting circuit, the controlling section controls selections by the first selector and the second selector so as to make phase difference detected at the phase-difference detecting section minimum, and data operation to a recording medium is executed based on a clock signal outputted from the delay circuit.