Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Hgst Netherlands, B.v.

Hiroshi Ikekame

Hisashi Takano

Yohji Maruyama

Takeo Yamashita

Kyo Akagi

Yuko Tsuchiya

Ryuji Tsuchiyama

Kyosuke Ono

Masahumi Mochizuki

Embodiments of the present invention provide a servo write medium, method and device for writing servo information by self servo write on the servo region formed from a flat section of the discrete track medium. The recording or write device yields the same servo characteristics as magnetic servo writing, is superior to pre-patterned servo, and delivers a greater write storage capacity with an even higher recording density. According to one embodiment, a self servo write method is used to write servo information on a flat section formed on a patterned disk on which discrete tracks are formed. Timing detection patterns (grooves) required for controlling the timing along the periphery during self servo write are formed by pre-patterning on the disk, and RRO error signals used for positioning control along the radius are written in the servo information on a flat section of the disk.

Magnetic recording media, method for servowriting on same, and hard disk drive

In a discrete track medium and a patterned medium, a meniscus adsorptive force is reduced and writing into adjacent tracks is prevented. A magnetic layer in lands or patterns in the discrete track medium or the patterned medium is formed into a cylindrical shelly or spherical shelly shape with a uniform thickness. Moreover, a height of cylindrical shelly land or a height of spherical shelly land is changed between 5 nm and 30 nm according to radial positions. Thus, an effect is achieved for providing a magnetic recording medium and a magnetic disk apparatus which are excellent in realizing higher recording density and higher reliability.

Magnetic recording medium having lands with curved upper surfaces and magnetic recording and reproducing apparatus

A current measurement method for measuring a current that flows in a transmission line of an electric circuit including steps of installing a magnetooptical device in a magnetic field which is generated based upon current that flows in the transmission line, making a polarized light on the magnetooptical device, and acquiring a current based upon the variation of the polarization of reflected light from the magnetooptical device on which the polarized light is incident.

Current measurement technique and current measurement apparatus

Devices and methods for generating a magnetic head-specific overshoot current which is combined with an alternating current waveform into a write current used by the magnetic head to store information on a magnetic medium. A processor analyzes the frequency of incoming write data and retrieves from a data table of an overshoot current amplitude and an overshoot current phase. This amplitude and phase information is sent to an overshoot current generator to generate an overshoot current that is responsive to the dynamic impedance properties of a magnetic write head during operation. The data table may have information related to one or many write heads, and the data table may be further subdivided based on additional dynamic characteristics of a write head that may affect the impedance thereof.

Overshoot current phase/amplitude control for hard disk drive write current

Magnetic disk apparatus includes an electric wiring capable of satisfying an electric condition under which high frequency recording higher than or equal to 200 MHz, a magnetic head having at least a recording device to a magnetic recording medium, and also the electric wiring corresponding to a recording current supplying device to this magnetic head are formed on a suspension member for mechanically suspending the magnetic head, the recording current being supplied to a magnetic head recording device by employing such electric wiring, the characteristic impedance of which is higher than a maximum impedance of the magnetic head recording device.

Disk drive having magnetic head conduction paths with arrangements to control impedance

The object of the invention is to provide technique and an apparatus for precisely measuring high frequency current that flows in a transmission line of a small impedance load circuit. A current waveform can be measured in wide bandwidth (at high-time resolution) and at high sensitivity without processing DUT (nondestructive) and without having an effect of the impedance of the apparatus (noninvasive) by installing a magnetooptical device in a magnetic field generated based upon current that flows in the transmission line, applying a bias magnetic field to the magnetooptical device by a magnetic field generator, making polarized light incident under the control of a position so that detection sensitivity is maximum and detecting the variation of polarization included in reflected light from the magnetooptical device.

Magnetic disk drive

The magnetic disk apparatus includes an electric wiring capable of satisfying an electric condition under which high frequency recording higher than or equal to 200 MHz can be accomplished. A magnetic head having at least a recording device for recording to a magnetic recording medium is provided as well as an electric wiring corresponding to a recording current supplying device for this magnetic head are formed on a suspension member for mechanically suspending the magnetic head. The recording current is supplied to a magnetic head recording device by employing such electric wiring, the characteristic impedance of which is higher than a maximum impedance of the magnetic head recording device.

Magnetic disk apparatus having an electric conducting path with a defined characteristic impedance and which interconnects a write element and a read/write integrated circuit

Growing community of inventors

Tokyo, Japan

Hiroshi Ikekame