Abstract: According to one embodiment, a magnetic disk device includes magnetic disks, a plurality of magnetic heads, and a control unit. A plurality of magnetic heads each includes a heat-assist unit which applies a preheating current of such magnitude that data already written to the magnetic disk is not erased to a near-field optical element for the preheat time. The control unit measures the time elapsing from a start of write to the time when a value of an index indicating the quality of a recording signal of data written by the magnetic head converges to within a first threshold range, and adjusts the preheat time for each of the magnetic heads in such a manner that the measured lapse time becomes less than or equal to a second threshold.

Abstract: According to one embodiment, among a plurality of magnetic heads, the larger the magnetic pole width of the magnetic pole of the magnetic head in the width direction of a recording track formed in a recording layer or the larger an area width of the magnetic head capable of reading the magnetic characteristics of an area of the recording layer on which magnetic recording has been carried out by means of the magnetic head, the farther is the magnetic head arranged outwardly from the vicinity of the center in the parallel arrangement direction of the magnetic disks.

Abstract: According to one embodiment, among a plurality of magnetic heads, the larger the magnetic pole width of the magnetic pole of the magnetic head in the width direction of a recording track formed in a recording layer or the larger an area width of the magnetic head capable of reading the magnetic characteristics of an area of the recording layer on which magnetic recording has been carried out by means of the magnetic head, the farther is the magnetic head arranged outwardly from the vicinity of the center in the parallel arrangement direction of the magnetic disks.

Abstract: According to one embodiment, a magnetic disk device includes a disk that includes a first track, a head that includes a heater, writes data to the disk, and reads data from the disk, and a controller configured to set a variation of a parameter related to a write process for the disk within one round of the first track to suppress a variation of an evaluation index corresponding to a write/read processing characteristic within one round of the first track.

Abstract: According to one embodiment, a magnetic disk device includes a disk that includes a first track, a head that includes a heater, writes data to the disk, and reads data from the disk, and a controller configured to set a variation of a parameter related to a write process for the disk within one round of the first track to suppress a variation of an evaluation index corresponding to a write/read processing characteristic within one round of the first track.

Abstract: According to one embodiment, a magnetic recording and reproducing device includes a perpendicular magnetic recording medium, a perpendicular magnetic recording head, a thermal assisted magnetic recording medium, and a thermal assisted magnetic recording head.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a read head that reads data from the disk, a write head that writes data into the disk, and an assist element that generates energy for improving write performance of the write head, and a controller that adjusts a degauss condition after a stop of a write process of the write head, based on a resistance value of the assist element, and adjusts a data format of the disk in accordance with the degauss condition, the resistance value being measured after data is written into the disk, and the write process having an influence on the resistance value.

Abstract: According to one embodiment, a magnetic recording and reproducing device includes a perpendicular magnetic recording medium, a perpendicular magnetic recording head, a thermal assisted magnetic recording medium, and a thermal assisted magnetic recording head.

Abstract: An image forming apparatus performs the following. An imaging range imaged by each of the plurality of imaging sensors includes an overlapping portion between the imaging sensors adjacent in a width direction orthogonal to a conveying direction along the conveying path. A hardware processor performs a calibration operation of a first sensor based on a color measuring result of a predetermined inspection image measured within a standard imaging range of the first sensor among the plurality of imaging sensors, and a standard imaging result within the standard imaging range imaging an inspection image with a same pattern as the inspection image. The hardware processor compares imaging results by the plurality of imaging sensors in the overlapping portions and performs the calibration operation of another sensor different from the first sensor using the standard imaging result as a standard.

Abstract: According to one embodiment, a magnetic disk device includes a disk having a first area, and a second area to which data is temporary written, a head including a write head which writes data to the disk, and an assisting element which generates energy which improves write performance of the write head, and a controller which writes data to the first area by supplying energy having a first value to the assisting element, and writes data to the second area by supplying energy having a second value different from the first value to the assisting element.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a read head that reads data from the disk, a write head that writes data into the disk, and an assist element that generates energy for improving write performance of the write head, and a controller that adjusts a degauss condition after a stop of a write process of the write head, based on a resistance value of the assist element, and adjusts a data format of the disk in accordance with the degauss condition, the resistance value being measured after data is written into the disk, and the write process having an influence on the resistance value.

Abstract: An image forming apparatus performs the following. An imaging range imaged by each of the plurality of imaging sensors includes an overlapping portion between the imaging sensors adjacent in a width direction orthogonal to a conveying direction along the conveying path. A hardware processor performs a calibration operation of a first sensor based on a color measuring result of a predetermined inspection image measured within a standard imaging range of the first sensor among the plurality of imaging sensors, and a standard imaging result within the standard imaging range imaging an inspection image with a same pattern as the inspection image. The hardware processor compares imaging results by the plurality of imaging sensors in the overlapping portions and performs the calibration operation of another sensor different from the first sensor using the standard imaging result as a standard.

Abstract: According to one embodiment, among a plurality of magnetic heads, the larger the magnetic pole width of the magnetic pole of the magnetic head in the width direction of a recording track formed in a recording layer or the larger an area width of the magnetic head capable of reading the magnetic characteristics of an area of the recording layer on which magnetic recording has been carried out by means of the magnetic head, the farther is the magnetic head arranged outwardly from the vicinity of the center in the parallel arrangement direction of the magnetic disks.

Abstract: An image forming apparatus performs the following. An imaging range imaged by each of the plurality of imaging sensors includes an overlapping portion between the imaging sensors adjacent in a width direction orthogonal to a conveying direction along the conveying path. A hardware processor performs a calibration operation of a first sensor based on a color measuring result of a predetermined inspection image measured within a standard imaging range of the first sensor among the plurality of imaging sensors, and a standard imaging result within the standard imaging range imaging an inspection image with a same pattern as the inspection image. The hardware processor compares imaging results by the plurality of imaging sensors in the overlapping portions and performs the calibration operation of another sensor different from the first sensor using the standard imaging result as a standard.

Abstract: According to one embodiment, a magnetic disk device includes a disk having a first area, and a second area to which data is temporary written, a head including a write head which writes data to the disk, and an assisting element which generates energy which improves write performance of the write head, and a controller which writes data to the first area by supplying energy having a first value to the assisting element, and writes data to the second area by supplying energy having a second value different from the first value to the assisting element.

Abstract: According to one embodiment, there is provided a disk device including a head, a disk, a first motor, and a first circuit. The disk has a recording surface. The first motor causes the head to seek along the recording surface. The first circuit can switch between a first state and a second state. The first state is a state where a current path of the first motor is electrically cut off from a first electricity storage unit. The second state is a state where the current path of the first motor is electrically connected to the first electricity storage unit.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a first write head and a second write head configured to write data to the disk and a read head configured to read data from the disk, and a controller configured to write write data to a first area of the disk with the first write head and to overwrite the write data written with the first write head in the first area with the second write head.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a first write head and a second write head configured to write data to the disk and a read head configured to read data from the disk, and a controller configured to write write data to a first area of the disk with the first write head and to overwrite the write data written with the first write head in the first area with the second write head.

Abstract: According to one embodiment, there is provided a magnetic disk drive comprising a magnetic disk, a magnetic head configured to read/write data from/to the magnetic disk, a signal processing circuit configured to convert data to be recorded on the magnetic disk into a write signal, and to output the write signal to the magnetic head that generates a recording magnetic field corresponding to the write signal, and a recording control circuit configured to control the signal processing circuit and the magnetic head to record, in a target recording area of the magnetic disk, first data in the target recording area with a recording magnetic field having a first frequency, and to write, second data different from the first data over the first data with a recording magnetic field having a second frequency higher than the first frequency.

Abstract: According to one embodiment, there is provided a disk device including a head, a disk, a first motor, and a first circuit. The disk has a recording surface. The first motor causes the head to seek along the recording surface. The first circuit can switch between a first state and a second state. The first state is a state where a current path of the first motor is electrically cut off from a first electricity storage unit. The second state is a state where the current path of the first motor is electrically connected to the first electricity storage unit.