Mitsubishi Chemical Corporation

Matsushita Electric Industrial Co., Ltd.

Mitsubishi Keikinzoku Kogyo Kabushiki Kaisha

Mitsubishi Gas Chemical Company, Inc.

Itsubishi Keikinzoku Kogyo Kabushiki Kaisha

Yuzo Seo

Yoji Arita

Toshihiko Kuriyama

Hiroyuki Ikeda

Ryuichi Yoshiyama

Mitsunori Mochida

Youji Arita

Junichi Kozu

Takeshi Kuriwada

Masahiro Kawashima

Shuichi Maeda

A magnetic pattern forming apparatus, which is designed to form a desired magnetic pattern on a magnetic disk having a magnetic layer on a substrate, is made up of a mask having a pattern identical or similar to the desired magnetic pattern, a projection optical system for exposing the magnetic disk to a spot-like energy beam coming through the mask to heat the magnetic layer for projecting the mask pattern to the magnetic disk at a one-to-one ratio or a predetermined reduction ratio, a magnetic field applying device for applying an external magnetic field to the magnetic disk, a control unit for conducting scanning with the spot-like energy beam with respect to the magnetic disk and the mask in their radial directions while rotating the magnetic disk and the mask.

Magnetic pattern forming method, magnetic pattern forming apparatus, magnetic disk, and magnetic recording apparatus

Method for forming a magnetic pattern in a magnetic recording medium, a magnetic pattern forming device, a magnetic recording medium and a magnetic recording device

A method and device for forming a magnetic pattern in a magnetic recording medium, a magnetic recording medium formed thereby and a magnetic recording device that includes a magnetic recording medium formed by this method and/or device. The magnetic recording medium has a magnetic layer, a protective layer, and a lubricant layer formed on a substrate in this order, and the magnetic pattern is formed by locally heating the magnetic layer and applying an external magnetic field to the magnetic layer.

METHOD FOR FORMING A MAGNETIC PATTERN IN A MAGNETIC RECORDING MEDIUM, METHOD FOR PRODUCING A MAGNETIC RECORDING MEDIUM, MAGNETIC PATTERN FORMING DEVICE, MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING DEVICE

A recording disk has a data area and a servo-burst area alternately arranged with each other in the circumferential direction of the disk. The servo-burst area has a servo-burst pattern having signal sections and non-signal sections arranged with a period &lgr; in the radial direction of the disk. The period &lgr; is expressed by &lgr;&equals;2p&times;n/m in terms of track pitch &ldquo;p&rdquo; of the disk, wherein n and m are integers prime to each other provided that n/m<2.

Data recording medium and data recording/reproducing device with increased storage capacity

The disclosure describes a magnetic recording medium having at least a magnetic layer, optionally by means of an under layer, on a non-magnetic substrate, wherein projections formed by irradiation of an energy beam and each having a height from 1 to 60 nm are provided at the number of 10,to 10,per 1 mm,on the surface of any one of the non-magnetic substrate, the under layer, the magnetic layer and the magnetic recording medium.

Magnetic recording medium, method of producing the same, and recording and reading-out method

A method for conducting data writing/reading-out utilizing a contact start and stop (CSS) system is provided. The system includes a magnetic disc having a data zone for writing/reading-out of data and a contact start and stop (CSS) zone having a taking-off/landing region, and a stopping region for contact start and stop operation of a magnetic head. A plurality of projections are provided in the CSS zone such that the relative height of the projections in the taking-off/landing region decreases in the radial outward direction from the center of the magnetic disc toward the data zone. An average gradient for the height of the projections in the taking-off/landing zone is between about 1.times.10.sup.-6 and about 5.times.10.sup.-5. Further, the maximum height of the projections in the CSS zone is greater than the flying height of the magnetic head in the data zone, and the minimum height of the projections in the CSS zone is lower than the flying height of the magnetic head in the data zone. The system also includes a contact-head for seeking and for spinning down/spinning up disc rotations on the sloped projections. Recording/reading operations are accomplished by flying the magnetic head at a height lower than the maximum height of the projections.

Method for data writing/read-out using a contact start and stop system

A texturing apparatus for applying a texturing to a magnetic recording medium, such as a magnetic disk including a hard drive. A substrate such as a magnetic disk is held by a substrate rotating system, which is capable of rotating the substrate. A movable laser beam source including an electro-optic modulation circuit directs a laser beam through a focusing element onto the surface of the substrate. The modulation circuit allows the laser beam to pulse at a frequency from 0.1 to 100 MHz. The focusing element allows a laser beam spot diameter of 0.2 to 4 .mu.m on the surface of the substrate. This texturing includes texturing the magnetic head contact start and stop (CSS) area of hard disks.

Texturing apparatus for magnetic recording medium and magnetic recording

An information recording medium and method arranges a plurality of information recording tracks in parallel to a running direction of an information recording medium and divides the tracks into a plurality of data blocks, and a servo-burst section between the data blocks. The servo-burst section has, alternately servo-burst-signal recording sections and servo-burst-signal non-recording section. The position of a recording/reproducing head is controlled by using a plurality of recording/reproducing head gaps provided in the head and detecting positional deviations of the head gaps from the centers of the information recording tracks. The deviations are detected from intensity changes of signals from the servo-burst-signal recording sections. The head position control is performed such that at least one of the two head gaps is located at a position to reproduce a signal from both of the servo-burst-signal recording section and the servo-burst-signal non-recording section simultaneously The placement of the servo-burst-signal recording/non-recording sections with respect to head gaps results in a ratio of the signals of the head gap located corresponding to the servo-burst-signal recording section with respect to the signal of the head gap located corresponding to the servo-burst-signal non-recording section as being a predetermined ratio.

Information recording medium and recording/reproducing method for

The disclosure describes a magnetic recording medium having at least a magnetic layer, optionally by means of an under layer, on a non-magnetic substrate, wherein projections formed by irradiation of an energy beam and each having a height from 1 to 60 nm are provided at the number of 10.sup.2 to 10.sup.8 per 1 mm.sup.2 on the surface of any one of the non-magnetic substrate, the under layer, the magnetic layer and the magnetic recording medium.

Magnetic recording medium, method of producing the same, and recording

Magnetic recording medium and recording/reproducing method therefor as

Signal compensation apparatus and method compensates for and removes errors due to error factors included in source signals x and y approximated by the sine function and cosine function, respectively, from a measurement apparatus such as a resolver or an encoder. Compensation is achieved by approximating the source signals x and y as expressions which include the terms due to the error factors, detecting the maximum values of x, x+y, etc., and determining coefficients corresponding to the error factors on the basis of the relationships between the maximum values and the coefficients, and removing the errors from the signals provided by the measurement apparatus.

Apparatus and method for compensating for noise in signals

A backelectromotive force of an aluminum electrolysis cell is measured by the steps of: (a) repeatedly measuring voltage V and current I of the cell at a short interval; (b) forming groups of data each including measured values thus obtained within a relative short period; (c) calculating a constant e and its variance Ve with reference to each data group according to a linear regression expressed by an equation:

Method of measuring backelectromotive forces of aluminum electrolysis

Increase or decrease in a quantity of alumina presenting in a bath or a metal in an aluminum electrolytic cell is detected and a quantity of electric power supplied to the cell is increased or decreased in accordance with the result of detection. The detection is made by calculating a difference between a quantity of alumina supplied to the cell during an interval between an instant at which a previous anode effect has occurred or was anticipated to occur and an instant at which a present anode effect occurs or is anticipated to occur, and the quantity of alumina consumed during the interval.

Method of controlling aluminum electrolytic cells

In an array of rectangular aluminum electrolytic cells, each cell is provided with a plurality of anode electrodes, a plurality of current collecting cathode bars parallel with shorter side walls and located at a bottom of the cell and a plurality of side cathode bus bars extending along longer side walls. The cathode bars are divided into a least two groups. The current flowing through respective groups is collected at their centers on the one side and current flowing through respective groups is collected at both ends thereof on the other side. The collected currents are supplied to the anode electrodes of a next cell.

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Kanagawa, Japan

Yuzo Seo