Abstract: A method of recording data into a recording medium by forming a recording region which is physically different from the nonrecorded portions is disclosed. The optical data recording/reproducing method includes a first trial writing operation in which trial writing data are recorded into the recording medium while changing the recording power conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set an optimum recording power. The method also includes a second trial writing operation in which trial writing data are recorded into the recording medium while changing the servo conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set optimum servo conditions.

Abstract: A disk type record playback device having a wobble signal extracting bandpass filter for controlling a filter's center frequency according to a frequency follow-up control loop including a dummy filter identical in configuration to a filter to be controlled, and a phase comparator is capable of controlling the center frequency of the bandpass filter with satisfactory accuracy. A frequency variable lowpass filter is provided in a preceding stage of the phase comparator constituting a frequency follow-up circuit and supplies a signal obtained by eliminating harmonic components from a frequency follow-up clock signal to the phase comparator. A cutoff frequency of the lowpass filter is changed in cooperation with a center frequency of the bandpass filter, based on a signal outputted from the frequency follow-up control loop.

Abstract: For the purpose of letting through a magnetic flux which reverses the magnetization of the magnetic layer of the magnetic disk, a write element requires a predetermined sectional area. However, if a cross section of a magnetic pole is structured as the one having a large aspect ratio, the pole becomes less capable of letting the magnetic flux through effectively. This phenomenon brings about a lower limit on the track width of the magnetic poles and the track density cannot be raised. In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.

Abstract: An output of a magnetic head changes depending on the environmental temperature of a magnetic disk. In particular, under cold temperature conditions, an output of the head largely decreases mainly due to an increase in coercivity of a magnetic recording medium, which degrades an error rate. In one embodiment of the invention, sense-current optimization processing of a magnetic disk drive comprises the steps of: measuring the environmental temperature; and after a sense-current value which is set from the viewpoint of the reliability of the magnetic head is defined as an upper limit, finding out a sense current Is that can achieve the best error rate (BER) at the temperature. While changing a value of the sense current Is inside the magnetic disk drive, an error rate is measured. Then, a sense current Is_opt at which the best error rate properties are achieved is selected as a new set value.

Abstract: In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.

Abstract: In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Abstract: To provide a spin-valve type magnetic head having high read output even if track width is narrow and high stability, a magnetic head according to the invention is provided with a spin-valve type magnetoresistive element in which a single magnetic domain turning ferromagnetic layer is formed on a soft magnetic free layer via a non-magnetic separating layer, the soft magnetic free layer and the single magnetic domain turning ferromagnetic layer are magnetostatically coupled at the end of track width, a closed magnetic circuit is formed and the soft magnetic layer has magnetization substantially induced in a direction substantially perpendicular to an external magnetic field.

Abstract: Provided is a thin film single pole head for perpendicular magnetic recording, which has a structure offering a high formatted volume, easy servo, difficulty of influencing a recording pattern on a medium, and capability of shortening processing time. This thin film single pole head for perpendicular magnetic recording is formed on a reproducing head composed of a pair of shield layers formed on a substrate, and a reproducing element formed therebetween. A structure is provided, where an auxiliary pole is not disposed between the reproducing element of the reproducing head and the main pole of a recording head when seen from a surface facing to recording media.

Abstract: A write head's material having a great thermal expansion coefficient expands due to Joule heat resulting from a write current and a temperature rise dependent on high-frequency core loss, thereby causing the head's flying surface to protrude toward a magnetic disk. This phenomenon is called TPR (thermal protrusion). It is essential that the flying height be accurately determined and managed in consideration of TPR. A magnetic disk drive for actual use or a magnetic disk drive that is in a testing process but similar to the one for actual use is used to measure TPR amount changes resulting from a write operation, store the resulting measured data in a memory or on the magnetic disk, and perform flying height management with the stored measured data. Further, flying height management is performed as needed in conjunction with a SMART function. The present invention makes it possible to perform high-reliability flying height management.

Abstract: In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Abstract: Provided is a thin film single pole head for perpendicular magnetic recording, which has a structure offering a high formatted volume, easy servo, difficulty of influencing a recording pattern on a medium, and capability of shortening processing time. This thin film single pole head for perpendicular magnetic recording is formed on a reproducing head composed of a pair of shield layers formed on a substrate, and a reproducing element formed therebetween. A structure is provided, where an auxiliary pole is not disposed between the reproducing element of the reproducing head and the main pole of a recording head when seen from a surface facing to recording media.

Abstract: Provided is a thin film single pole head for perpendicular magnetic recording, which has a structure offering a high formatted volume, easy servo, difficulty of influencing a recording pattern on a medium, and capability of shortening processing time. This thin film single pole head for perpendicular magnetic recording is formed on a reproducing head composed of a pair of shield layers formed on a substrate, and a reproducing element formed therebetween. A structure is provided, where an auxiliary pole is not disposed between the reproducing element of the reproducing head and the main pole of a recording head when seen from a surface facing to recording media.

Abstract: In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Abstract: A disk type record playback device having a wobble signal extracting bandpass filter for controlling a filter's center frequency according to a frequency follow-up control loop including a dummy filter identical in configuration to a filter to be controlled, and a phase comparator is capable of controlling the center frequency of the bandpass filter with satisfactory accuracy. A frequency variable lowpass filter is provided in a preceding stage of the phase comparator constituting a frequency follow-up circuit and supplies a signal obtained by eliminating harmonic components from a frequency follow-up clock signal to the phase comparator. A cutoff frequency of the lowpass filter is changed in cooperation with a center frequency of the bandpass filter, based on a signal outputted from the frequency follow-up control loop.

Abstract: A method for reproducing information on a recording medium includes irradiating electromagnetic energy or light to the recording medium from one side with respect to the recording medium, applying a recording magnetic field to an electromagnetic energy or light irradiated position on the recording medium from the one side of irradiating electromagnetic energy or light, and detecting magnetic leakage flux emerging from the recording medium from the one side of irradiating electromagnetic energy or light.

Abstract: When the amount of position error PE of a magnetic head meets the condition of Ewf>PE>=Eww for two threshold values Ewf and Eww meeting Ewf>Eww, the track is registered in the track information table as a track requiring rewrite and the tracks on both sides neighboring to the track are temporarily write-inhibited. The data of the track is rewritten on another track later so as to maintain the data. By doing this, the offtrack of the recording track can be made smaller without sacrifice of the access speed and the occurrence probability of write fault can be reduced. Furthermore, the reliability of a magnetic disk apparatus can be improved.

Abstract: To provide a spin-valve type magnetic head having high read output even if track width is narrow and high stability, a magnetic head according to the invention is provided with a spin-valve type magnetoresistive element in which a single magnetic domain turning ferromagnetic layer is formed on a soft magnetic free layer via a non-magnetic separating layer, the soft magnetic free layer and the single magnetic domain turning ferromagnetic layer are magnetostatically coupled at the end of track width, a closed magnetic circuit is formed and the soft magnetic layer has magnetization substantially induced in a direction substantially perpendicular to an external magnetic field.

Abstract: For the purpose of letting through a magnetic flux which reverses the magnetization of the magnetic layer of the magnetic disk, a write element requires a predetermined sectional area. However, if a cross section of a magnetic pole is structured as the one having a large aspect ratio, the pole becomes less capable of letting the magnetic flux through effectively. This phenomenon brings about a lower limit on the track width of the magnetic poles and the track density cannot be raised. In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.

Abstract: A method for reproducing information on a recording medium includes irradiating electromagnetic energy or light to the recording medium from one side with respect to the recording medium, applying a recording magnetic field to an electromagnetic energy or light irradiated position on the recording medium from the one side of irradiating electromagnetic energy or light, and detecting magnetic leakage flux emerging from the recording medium from the one side of irradiating electromagnetic energy or light.

Abstract: An information recording apparatus using a recording medium which holds information by reversed magnetic domains on a perpendicular magnetic recording film includes an irradiation unit for applying electromagnetic energy or light onto the recording medium, and a magnetic flux detection unit for detecting magnetic leakage flux emerging from the recording medium, the magnetic flux detection unit being disposed on the same side as the irradiation unit with respect to the recording medium. As a result, both side recording of the recording medium can be conducted.