Hitachi, Ltd.

International Business Machines Corporation

Hitachi Microcomputer Engineering, Ltd.

Kogyo Gijutsuin

Takashi Toyooka

Ryo Suzuki

Hirokazu Aoki

Masatoshi Takeshita

Hideto Niijima

Mamoru Sugie

Teruaki Takeuchi

Naoki Kodama

Yoshinori Sakaue

Shigeru Yoshizawa

Toshihiro Sato

Akashi Satoh

Nobuo Saito

Norio Ohta

Yutaka Sugita

Hideo Asano

Kazutoshi Yoshida

Shinsaku Chiba

Harukazu Miyamoto

Shigeru Nakamura

Tadashi Ikeda

Hirofumi Sukeda

Atsushi Saito

Toshimitsu Kaku

Hiroshi Uchida

Kazuo Shigematsu

Fumiyoshi Kirino

Masahiro Ojima

Takeshi Nakao

Yoshinori Miyamura

Yoshiaki Sonobe

Masahiko Takahashi

Toshio Niihara

Tsuneo Suganuma

Yoji Maruyama

Atsushi Asano

Hiroshi Umezaki

Shinzo Matsumoto

Kazuhiro Ishida

Hirofumi Ohta

Yoshihiro Ikeda

Koichi Mayama

Tatsuo Okahashi

Yoshiuki Tagashira

Kazuya Kamiyama

A perpendicular magnetic recording medium wherein a perpendicular magnetic film is formed on a substrate or a nonmagnetic film, and the perpendicular magnetic film contains Co and Cr, the content of the Cr being 22 at. % or higher but 30 at. % or less. The medium is used in a magnetic recording disk drive using a magnetoresistive read head.

Perpendicular magnetic recording medium and magnetic recording device

An array of memory cells is physically divided into a data area and a tag area so that respective parts of the two areas share a word line but can be separately erased en bloc. The data area and tag area sharing one word line constitute a single logical unit. In the logical unit, the tag area stores location information for defective memory cells in the corresponding data area. On the basis of this information, the system avoids the use of the defective memory cells. The defective memory cell information is programmed in a test step performed after chip manufacture and, at the same time, ECCs are generated for the defective memory cell information and written to the tag area. Furthermore, the system is informed of the invalidity of the data area that shares a word line with a tag area by writing predetermined data to the tag area. Even when the data area is erased en bloc, the tag area is not erased and the defective memory cell information is retained there.

Flash-erase-type nonvolatile semiconductor storage device

A nonvolatile memory with flash erase capability includes a plurality of clusters each having a plurality of sectors, each of the sectors holding the attribute information for identification. A cluster information sector is placed at the top of a cluster to which it belongs. A data sector is placed in a data area which is the region other than the top of the cluster. A controller connected to the nonvolatile memory creates a cluster information copy sector when erasing a cluster, and reconstructs cluster management information from the cluster information copy sector when initializing a cluster, thereby forming a cluster information sector. Accordingly, endurance against failure such as power failure in a solid state file apparatus using the nonvolatile memory is improved.

Nonvolatile memory with flash erase capability

A nonvolatile memory-with cluster-erase flash capability. A cluster information sector is included in each of N clusters, the cluster information sector of each cluster being written with the sequence number assigned to the cluster so that no two clusters have the same sequence number. When erasing a given sector, a controller saves its sequence number prior to erasure. Then, when initializing a given erased sector, the controller sets its sequence number to a value greater than the current maximum sequence number. The controller writes user data to sectors other than the cluster information sector for the cluster thus initialized according to their address sequence. Accordingly, an invalid sector can be distinguished from a valid sector without using an overwrite approach.

Nonvolatile memory with cluster-erase flash capability and solid state

An array of memory cells is physically divided into a data area and a tag area so that respective parts of the two areas share a word line but can be separately erased en bloc. The data area and tag area sharing one word line constitute a single logical unit. In the logical unit, the tag area stores location information for defective memory cells in the corresponding data area. On the basis of this information, the system avoids the use of the defective memory cells. The defective memory cell information is programmed in a test step performed after chip manufacture and, at the same time, ECCs are generated for the defective memory cell information and written to the tag area. Furthermore, the system is informed of the validity of the data area that shares a word line with a tag area by writing predetermined data to the tag area. Even when the data area is erased en bloc, the tag area is not erased and the defective memory cell information is retained there.

A nonvolatile memory with cluster-erase flash capability. A cluster information sector is included in each of N clusters, the cluster information sector of each cluster being written with the sequence number assigned to the cluster so that no two clusters have the same sequence number. When erasing a given sector, a controller saves its sequence number prior to erasure. Then, when initializing a given erased sector, the controller sets its sequence number to a value greater than the current maximum sequence number. The controller writes user data to sectors other than the cluster information sector for the cluster thus initialized according to their address sequence. Accordingly, an invalid sector can be distinguished from a valid sector without using an overwrite approach.

A magnetic field of a polarity corresponding to information to be recorded is applied while a recording spot having a high energy is irradiated to a magneto-optical recording medium to record domains representing the information along a track. The recorded domains are read out by a reproducing spot having a lower energy than the recording spot and a high resolution power along the track. A recording head has an optical system for irradiating the recording spot having the high energy to the magneto-optical recording medium and a magnetic head for applying a magnetic field having a polarity thereof switched in accordance with the information to be recorded, to an irradiation area of the recording spot, a reproducing head has an optical system for irradiating the reproducing spot having the low energy by a laser beam having a wavelength of no larger than 600 nm and a magneto-optical signal detector for detecting a displacement of a polarization plane of a reflected light of the reproducing spot to read out the recording domains. The magneto-optical recording medium is made of a recording film having a multi-layer structure of alternate lamination of metal layers and dielectric layers.

Magneto-optical recording and reproducing method, magneto-optical memory

This invention accomplishes low power consumption by a drive circuit for a Bloch line memory, which includes a power source, a bias magnetic field coil, a plurality of switching means and means for returning the power supplied to the bias magnetic field to the power source. The present invention can set the waveform of a pulse current (coil current) to a desired waveform by particularly using a transformer, and can improve the transfer characteristics of the Both line pair.

Drive circuit for Bloch line memory

In a magnetic bubble generator having an ion-implanted track (1), a conductor pattern is composed of hairpin conductor patterns (5, 6) of two layers with an insulating layer (12) interlaid, and a part of intersection of the fore end parts of the gaps of these hairpin conductor patterns (5,6) is positioned in the vicinity of a cusp (4) of the ion-implanted track (1). The hairpin conductors may be electrically connected to each other and may be supplied by a common source. Thereby an error to be caused by a generated bubble stretching so much as to be divided into a plurality of pieces can be prevented, and the bubble can be generated by a small current pulse, while the amplitude margin thereof is enlarged.

Magnetic bubble generator using plural conductors with common current

In a magnetic bubble memory device in which a major line and minor loops are constituted by ion-implanted tracks, a gate is constituted having two functions, i.e., having a replicate function and a pseudo swap function using conductor patterns of two layers that overlap on both the major line and on the minor loops. By controlling the pulsed current supplied to the conductor patterns of the two layers, the replicate function divides the bubble in the minor loop into two bubbles, so that one of the bubbles is taken onto the major line and is propagated to the detector. The pseudo swap function annihilates the bubble in the minor loop, divides the bubble on the major line into two bubbles and introduces one of them into the minor loop, thereby to realize the same function as that of the conventional swap gate.

Magnetic bubble memory device

In case of rewriting data by means of an erasable optical disc memory recording new data after having erased a series of data already stored, directory data written in an optical disc memory in order to control the written data are transferred to an external directory memory and write-in and read-out are controlled by using the directory memory. For rewriting data, which have been already recorded and which are recorded under a specified file name, the data are not erased and renewed data are written in another recording region, where recording is possible. The data, which have become unnecessary as the result of renewal, are erased during a period of time, when the optical disc memory is not accessed.

Method and apparatus for controlling renewal of data in optical disc

In a magnetic bubble memory device employing ion-implanted tracks as minor loops for data storage, there is proposed a magnetic bubble memory element employing a minor loop having a folded structure and a turn composed of three tips formed convexly toward an ion-implanted area and two cusps as an inside turn for accomplishing the folding with a center as the ion-implanted area. In this inside turn, the line connecting between the two cusps of the turn includes a gradient in the range of 90 degrees to 120 degrees in relation to the ion-implanted straight line tracks.

A hybrid magnetic bubble memory device comprising soft magnetic material propagation tracks and ion-implanted propagation tracks. In the soft magnetic material propagation track region, a layer made of a heat-resistant polymer was provided as an interlaminar insulating layer between a conductor and a pattern of a soft magnetic material. An insulator film made of a heat-resistant polymer was provided on the pattern made of a soft magnetic material. A passivation film made of an inorganic material was provided on the ion-implanted propagation tracks and the insulator film made of a heat-resistant polymer.

A magnetic bubble memory device comprises contiguous-disk ion-implanted magnetic bubble propagation tracks formed by implanting selectively ions in a magnetic layer which can hold magnetic bubbles. At least one of the disks which form the ion-implanted bubble tracks and each of which may have a circular or square shape, is configured to include a combination of arcs of circles having different curvatures or a combination of sides of squares having different sizes.

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Sayama, Japan

Takashi Toyooka