Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Reijiro Tsuchiya

Takehiko Hamaguchi

Mikio Suzuki

Hajime Aoi

Yasuhide Ouchi

Nobumasa Nishiyama

Hisashi Takano

Makoto Saito

Atsushi Saito

Yoshihiro Shiroishi

Makoto Koizumi

Kyo Akagi

Takashi Kawabe

Hideki Zaitsu

Masuo Umemoto

Futoshi Tomiyama

Kouichirou Wakabayashi

Yasuhiro Katoh

Naoki Sato

Toru Matsushita

Tetsuya Makiura

Katsuro Watanabe

Yoshihisa Kamo

Kiyoshi Matsumoto

Takashi Tamura

Yosuke Hamada

Makoto Saitoh

Yoshihasa Kamo

A conventional magnetic head has a structure, in which a MR element and a recording element are stacked. The influence of a recording magnetic field on the magnetically sensitive portion of a reproduction element is lessened and the performance of the MR element is stabilized. Also, the reliability of the magnetic disk drive using a MR element is enhanced. The magnetic disk drive uses a composite magnet head, which has a plurality of reproduction elements arranged such that the magnetically sensitive layer of a reproduction element of the composite magnetic head does not overlap with the normal direction projection of the recording element, and which lessens the influence of a recording magnetic field on the magnetically sensitive portion of each reproduction element.

Composite magnetic head arranged so the reproducing elements do not overlap a pole of a recording element

A magnetic recording disk drive can prevent the deterioration of the head off-track characteristics and the reduction of the drive performance even when an erase band asymmetry resulting from a skew angle exists. A write inhibit slice value for an inner peripheral side offset is made smaller than a write inhibit slice value for an outer peripheral side offset at a position where an erase band on the inner peripheral side is greater than an erase band on the outer peripheral side, so that the adjacent track on the outer peripheral side cannot easily erase a data track. On the contrary, the inner periphery and the outer periphery are paraphrased at a position where the erase band on the outer peripheral side is greater than the erase band on the inner peripheral side.

Magnetic recording disk drive

A conventional magnetic head has a structure, in which a MR element and a recording element are stacked. The influence of a recording magnetic field on the magnetically sensitive portion of a reproduction element is lessened and the performance of the MR element is stabilized. Also, the reliability of the magnetic disk drive using a MR element is enhanced. The magnetic disk drive uses a composite magnetic head, which has a plurality of reproduction elements arranged such that the magnetically sensitive layer of a reproduction element of the composite magnetic head does not overlap with the normal direction projection of the recording element, and which lessens the influence of a recording magnetic field on the magnetically sensitive portion of each reproduction element.

Composite magnetic head, magnetic disk drive using the head, and control method for the magnetic disk

A magnetic storage apparatus exploits the inherent characteristics of a magnetoresistive element to improve the performance of a magnetic head employing the element. Variations in element height or element thickness of the magnetoresistive element are considered in the selection of a sense current appropriate to the element size, by measuring the voltage between the terminals of the magnetoresistive head and controlling the sense current so that the output reference voltage approaches a predetermined value. In another embodiment, the sense current is controlled so that the voltage amplitude or a reference amplitude are set to a predetermined value. In both embodiments, a conversion table is preferably used to relate voltage amplitudes with sense currents, whereby an appropriate sense current is selected based upon the voltage amplitude.

Magnetic storage apparatus using a magnetoresistive element

In a magnetic disk device, a deterioration of performance caused by an environmental variation is suppressed by utilizing an automatic adaptation function in a read/write channel IC. A gate provides a timing for the automatic adaptation of an equalization coefficient, a signal from the gate is given to a read-gate input terminal of the read/write channel IC, and the gate for the automatic adaptation is opened before reading data from a destination sector to be read. The automatic adaptation is started, whereby coefficients for equalization are adapted to signal wave forms before reading data.

Magnetic disk device and automatic adaptation method of its parameter

Magnetic recorder and magnetooptical recorder

Storage apparatus using a magnetoresistive head that employs a sense

A magnetic digital storage method and system which can improve a recording density and can reduce a cross-talk upon reproducing. An inputted high-speed digital signal is converted to a plurality of low-speed digital signal sequences by a recording circuit and each of the low-speed signal sequence is recorded onto a plurality of adjacent recorded tracks of a recording medium by integrated parallel recording heads. One servo signal is commonly recorded to the plurality of recorded tracks. Further, when recording the digital signal to the adjacent recorded tracks of the recording medium, a delay of a signal that is applied to each recording head is adjusted such that the phases of magnetic transition points given by the recording signal in the adjacent recorded tracks are not identical in the circumferential direction.

Magnetic digital storage method and system wherein magnetic transition

An evaluation system for a signal waveform includes a first delay element for delaying a clock signal, a second delay element for delaying the output of the first delay element, and third and fourth delay elements for delaying the output of the second delay element. A first detector receives the output of the first delay element and the signal waveform for outputting binary data, a second detector receives the output of the second delay element and the signal waveform for outputting binary data, a third detector receives the output of the third delay element and the signal waveform for outputting binary data, and first, second and third shift registers receive output data of the first, second and third detectors and the output of the fourth delay element. A comparator unit compares data in the first, second and third shift register with a particular data pattern, and a counter counts output pulses of the comparator unit, the output of the second detector being output as a read data output. The distribution of peak pulses in a detection window is thereby determined.

Diagnostic system of magnetic recording channel and magnetic disk drive

A readout circuit in magnetic recording device is disclosed, in which a test data signal for detecting an error in the characteristics of an automatic equalizer is recorded in a predetermined position of each track of a magnetic recording medium. In readout mode, a test data signal for a selected track is read out first, and this signal is compared with a reference signal dependent on the system conditions to determine an error from the reference signal. The optimum equalization coefficient is determined to eliminate this error from the reference signal and set in the equalizer. The data is readout under the optimum equalization characteristics thus set.

Readout circuit in magnetic recording device

A readout circuit in magnetic recording device is disclosed, in which a test data signal for detecting an error in the characteristics of an automatic equalizer is recorded in a predetermined position of each track of a magnetic recording medium. In readout mode, a test data signal for a selected track is read out first, and this signal is compared with a reference signal dependent on the system conditions to determine an error from the reference signal. The optimum equalization coefficient is determined to eliminate this error from the reference signal and is set in the equalizer. The data is readout under the optimum equalization characteristics thus set.

A signal read out circuit included in a magnetic recording device is disclosed in which plural kinds of slice levels are used simultaneously for a reproduced analog waveform to produce a plurality of gate signals corresponding to the slice levels, and it is judged on the basis of the gate signals whether each portion of the reproduced waveform is correct or not in producing a digital output.

Multi slice level signal circuit

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Fujisawa, Japan

Reijiro Tsuchiya