Patent ID: 8295140
Filing Date: 2012-10-23
Classification: G11B

Abstract:
1. A recording and reproducing apparatus comprising: an optical head unit that irradiates a laser beam on an optical recording medium and performs writing and readout of information represented by marks and spaces on the optical recording medium; a laser-driving-pulse generating unit that generates a laser driving pulse corresponding to information to be recorded, supplies the laser driving pulse to the optical head unit, and causes the optical head unit to execute laser beam irradiation for recording; an evaluation-value measuring unit that measures, on the basis of a signal read out from the optical recording medium by the optical head unit, an evaluation value representing an error of an edge position of the mark; and a control and calculating unit that causes the recording and reproducing apparatus to separately execute, concerning plural mark lengths to be adjusted among mark lengths of the laser driving pulse, for each of sets of mark lengths grouped in advance, trial writing with shift amounts of edge positions of a laser driving pulse concerning the mark lengths belonging to the set changed, causes the recording and reproducing apparatus to execute readout of a signal recorded by the execution of the trial writing, causes the evaluation value measuring unit to measure an evaluation value under setting of the respective shift amounts, and obtains, on the basis of the measured evaluation values, an optimum edge shift amount of the laser driving pulse for each of the mark lengths to be adjusted, wherein the control and calculating unit obtains the optimum edge shift amount through a calculation, when, concerning each of the sets of the grouped mark lengths, types of edges positions to be adjusted among edge positions of laser driving pulses concerning the mark lengths belonging to the set is put as q types (q is an integer equal to or larger than 2) and types of edge positions of the marks for which the evaluation values should be measured are put as p types (p is an integer equal to or larger than 2), and a shift amount from an edge position set in advance as an initial strategy of the respective q types of edge positions is represented as vector w, the evaluation value measured concerning the respective p types of edge positions of the marks is represented as vector m, the evaluation value concerning the respective p types of edge positions of the marks measured in a setting state of the edge positions as the initial strategy is represented as m interference sensitivity representing behavior of the evaluation values concerning the edge positions of the marks with respect to the shift amounts of the edge positions of the laser driving pulse is represented by a matrix C of p×q, assuming that a relation represented by the following formula holds, the control and calculating unit causes the recording and reproducing apparatus to execute, concerning the edge positions, trial writings respectively in q+1 ways of setting states of shift amounts of the edge positions, causes the recording and reproducing apparatus to execute readout concerning each of signals recorded by the execution of the trial writing, causes the evaluation-value measuring unit to measure the evaluation values concerning the p types of edge positions of the marks, obtains the matrix C as the interference sensitivity and the evaluation value m and obtains an optimum edge shift amount concerning the q types of edge positions.