Abstract: A magnetic disk device includes a magnetic disk that includes a plurality of zones divided in a radial direction, a plurality of tracks in each of the zones, and a plurality of sectors in each of the tracks divided in a circumferential direction, a magnetic head configured to read and write data to and from the magnetic disk, and a control unit configured to determine a setting value of a recording current to be applied to the magnetic head when writing to each of a plurality of sections of a first sector, based on error rates in data read from a second sector that is in the same zone as the first sector and to which a write was performed while changing setting values of recording currents applied to the magnetic head while writing to each of a plurality of sections of the second sector.

Abstract: An optical disk device includes a first control circuit controlling a light quantity of a semiconductor laser according to a first light quantity set value corresponding to a first light quantity resolution; a second control circuit controlling the light quantity of the semiconductor laser according to a second light quantity set value corresponding to a second light quantity resolution that is smaller than the first light quantity resolution; and a drive circuit driving the semiconductor laser following the first and second control circuits.

Abstract: According to one embodiment, an optical disc device includes a semiconductor laser which generates laser light to irradiate an optical disc, and an automatic power control circuit which detects an optical output of the semiconductor laser, sets driving current data equalized to reflect the detection result, and drives the semiconductor laser based on the driving current data. This optical disc device further includes a protection circuit which monitors the driving current data set in the automatic power control circuit to invalidate the driving current data in a case where the abnormality of the driving current data is detected.

Abstract: An optical disk device includes: a light emitting element which applies light to an optical disk; a light detection unit which receives the light emitted from the light emitting element and outputs an intensity signal corresponding to an intensity of the light emitting element; a difference detection unit which generates a control signal based on a difference between the intensity signal and a reference intensity signal; a first current supply unit which supplies a first current based on the control signal; a second current supply unit which supplies a second current; a current adding unit which adds the first and second currents to generate a third current and supplies the third current to the light emitting element; an optical pickup on which the first current supply unit and the adding unit are placed; and a circuit board on which the second current supply unit is placed.

Abstract: Provided is an optical disc apparatus including: an optical pickup configured to form marks and spaces on the optical disc by using a recording power and a erasing power respectively; a control unit configured to write test data on trial on the optical disc while changing the recording power and the erasing power and to determine an optimum recording power and an optimum erasing power; and a nonvolatile memory configured to store a correction coefficient which has been obtained in advance. The control unit corrects a power ratio of a recommended recording power to a recommended erasing power by the correction coefficient stored in the memory, and controls to write the test data on trial on the optical disc while changing the recording power and a erasing power, the erasing power being acquired from the recording power and the corrected power ratio.

Abstract: According to one embodiment, an optical disc apparatus includes a laser diode configured to irradiate a laser beam onto an optical disc, a laser drive circuit configured to supply the laser diode with a laser drive current superposed with a high frequency electric current according to defined conditions of the high frequency electric current in order to turn the laser beam output from the laser diode to a multimode laser beam, a detecting section configured to detect a frequency condition of the high frequency electric current to reduce a quantity of interlayer crosstalk, and a setting section configured to set the detected condition in the laser drive circuit.

Abstract: In an optical disc apparatus, a CPU controls a focus control circuit, and a focus offset for adjusting a height of an objective lens is set. A spindle motor control circuit, a laser driver circuit, and an RF amplifier are controlled. When an optical disc is rotated by using the set focus offset in a state where a tracking servo is not performed, an envelope of a full addition signal or a RF signal obtained from each focused focal point corresponding to the objective lens in a land and a groove is detected. An amplitude level of the envelope is measured, and a focus control circuit is controlled. By using the focus offset with which the amplitude level of the envelope of the full addition signal or the RF signal is minimized, a focus offset used when recording or reproduction of the optical disc is performed is determined.