Tdk Corporation

Samsung Electronics Co., Ltd.

National Institute of Advanced Industrial Science and Technology

Tatsuhiro Kobayashi

Takashi Kikukawa

Narutoshi Fukuzawa

Junji Tominaga

In-oh Hwang

Takayuki Shima

Hiroyasu Inoue

Tatsuya Kato

Koji Mishima

Jae-Cheol Bae

Masashi Kuwahara

Kyung-geun Lee

Hajime Utsunomiya

Hyun-Soo Park

Yoshikazu Soeno

Tsutomu Aoyama

Makoto Moriya

Akimasa Kaizu

Toshiki Aoi

Joo-Ho Kim

Takashi Nakano

Sadaharu Yoneda

Joo-ho Kim

Hui Zhao

A magnetic recording device includes a magnetic recording medium, a microwave assisted magnetic head having a main magnetic pole for generating a recording magnetic field, and a spin torque oscillator provided near the main magnetic pole for generating a microwave magnetic field, a recording current supply part for supplying a recording current to recording coils according to recording current waveform data, a drive current supply part for supplying a drive current to the spin torque oscillator, and a drive current control part for controlling supply of the drive current by the drive current supply part based on the data. Taking into consideration as an indicator whether a polarity reversal interval included in the data exceeds a threshold time, the drive current control part controls the drive current supply part so as not to substantially lower the quality of signals recorded on the magnetic recording medium.

Magnetic recording device and magnetic recording method

A magnetic recording device includes a magnetic disk and a magnetic head that performs magnetic recording to the magnetic disk. The magnetic head includes a main magnetic pole layer and a microwave generating element. The magnetic recording device further includes a microwave generating element driving current control circuit. The microwave generating element driving current control circuit, during the magnetic recording, applies a microwave generating element driving current at a first current level to the microwave generating element for a period that is from at the latest a polarity reversal of the recording current before a subsequent polarity reversal of the recording voltage, and thereafter applies another microwave generating element driving current at a second current level, which is smaller than the first current level, to the microwave generating element, or stops the application of the another microwave generating element driving current until the polarity reversal of the recording voltage.

Microwave-assisted magnetic recording device and method using non-constant microwave

A method of determining an optimum reproduction condition of a first mark recorded on an optical recording medium that is smaller than a resolution of a pickup to reproduce the first mark. The method includes obtaining an optimum reproduction condition of a second mark having a length which closely approximates the resolution of the pickup, and determining the optimum reproduction condition of the first mark using the obtained optimum reproduction condition of the second mark.

Method and apparatus to determine an optimum reproducing condition on an optical recording medium

A super-resolution optical recording medium has at least a recording layer and a super resolution layer on a substrate. In the recording layer, a minimum recording mark is formed with spaces within a beam spot of a laser beam in recording. The minimum recording mark has a size of a resolution limit of a reproduction optical system or less, and can be reproduced by the reproduction optical system due to the existence of the super solution layer. The minimum recording mark in an AFM image takes the shape of a convex arc on a leading edge thereof and the shape of a concave arc on a trailing edge thereof (the AFM image is a plan view which can be observed on a surface when the light transmission layer is removed), and spaces have the similar shape to these.

Super-resolution optical recording medium and method for recording information on super-resolution optical recording medium

An optical recording medium includes a substrate, a first dielectric layer, a recording layer, a second dielectric layer, a super-resolution layer, and a third dielectric layer, which are provided in that order. The super-resolution layer is formed of a material configured such that voids are generated when the material is irradiated with DC light at a predetermined irradiation power for 1 to 300 seconds. Therefore, super-resolution reproduction can be made such that the irradiation power of a readout laser beam does not depend on the size of a recording mark.

Optical recording medium and method for reproducing information from optical recording medium

A magnetic recording medium enhances the quality of a reproducing signal. The magnetic recording medium has a servo pattern formed in a servo pattern area on at least one surface of a disk-shaped substrate by a concave/convex pattern having convex portions (recording areas) and concave portions (non-recording areas), and a data track pattern formed by the concave/convex pattern in a data recording area on the at least one surface of the disk-shaped substrate. In a state where recording data is not recorded in the data recording area, the convex portions in the servo pattern area are DC-magnetized, and the convex portions in the data recording area are AC-magnetized.

Magnetic recording medium, recording and reproducing device, magnetic recording medium-magnetizing method, and magnetic recording medium-magnetizing device

A method and apparatus for measuring the read stability of an optical disc are provided. Specifically, readout of the optical disc is repeated at each of at least two read laser beams powers being different from each other. A graph is drawn in which the inverses of the read powers are plotted on a horizontal axis and in which on a vertical axis is plotted the logarithm of a repeated readout number for each of the read powers. Here, the repeated readout number is the number of repetitions of the readout when a characteristic value for the number of repetitions of the readout varies and reaches a predetermined value. The read stability of the optical disc is evaluated by using the gradient of the graph.

Method for evaluating read stability of optical disc and information reproduction apparatus

A method of optimizing a writing condition of an optical recording medium, including writing test pattern data with the writing condition on the optical recording medium, comparing an error pattern binary signal detected by reproducing the written test pattern data with a correct pattern binary signal of the test pattern data, and determining an optimum writing condition of the optical recording medium based on a result of the comparison.

Writing condition optimizing method and apparatus, and optical recording medium

A super-resolution optical recording medium has at least a recording layer and a super resolution layer on a substrate. A recording mark with the size of a resolution limit or less and a space with the size of the resolution limit or less are formed in the super-resolution optical recording medium by adjusting the intensity of a laser for recording or an emission pattern of the laser for recording such that at least the recoding mark with the size of the resolution limit or less out of recording marks in a modulation code is formed into a concave section with respect to a not-recorded section.

A method for recording information on an optical recording medium in which a laser beam modulated into one or a plurality of write pulses with one or a plurality of write powers in accordance with target data to be written is projected onto a recording layer of the optical recording medium to form a record mark. During recording the information on the optical recording medium, a data level and a weight index are assigned to each channel bit in reference data trains before and after the target data. Recording compensation of the target data is carried out in accordance with the sum totals of the products of the data level and the weight index in the reference data trains, so that it is possible to easily carry out high a real recording by writing fine mark/space trains.

Method and apparatus for recording information on optical recording medium with compensation for thermal effects in ultra-high-density optical recording and reproducing system

A method for determining recording laser power on a super-resolution optical recording medium, on which information is recorded on a super-resolution optical recording medium by irradiating a laser beam modulated into a recording pulse train according to recording data to thereby form a recording mark train including recording marks and spaces smaller than the resolution limit of a reproduction optical system and recording marks and spaces equal to or larger than the resolution limit, is provided. At the time of recording, the method determines a minimum value and a maximum value of recordable laser powers determined by test-writing before recording, and determines a maximum value of a recordable range of laser power by adding to the minimum value one-third of a difference between the maximum value of the recordable laser powers and the minimum value. The method determines an optimal range of recording laser power from the minimum value of recordable laser powers to the maximum value of the recordable range.

Method for determining recording laser power for super-resolution optical recording medium and apparatus for recording information on super-resolution optical recording medium

An optical recording disc includes a substrate, a third dielectric layer, a light absorption layer, a second dielectric layer, a decomposition reaction layer containing platinum oxide as a primary component, a first dielectric layer, and a light transmission layer. The decomposition reaction layer has a thickness of 2 nm to 20 nm, and the optical recording disc is constituted so that when it is irradiated with a laser beam from the side of the light transmission layer, the platinum oxide contained in the decomposition reaction layer as a primary component is decomposed into platinum and oxygen. A bubble pit is formed in the decomposition reaction layer by thus generated oxygen gas, and fine particles of the noble metal precipitate into the bubble pit, thereby forming a recording mark in the decomposition reaction layer.

Optical recording disc

In a data recording and readingout system in which data is recorded and readout, or is readout on, or from an optical recording mediumby irradiating a laser beam having a wavelength '&#x3bb;' via an objective lens of a numerical aperture 'NA' onto said optical recording medium, while the optical recording medium contains a layered structure formed by sandwiching a dielectric layerbetween a recording layerand an optical absorption layerwith respect to the optical recording mediumarranged in such a manner that data recorded by a recorded mark train can be readout and the recorded mark train contains a recorded mark smaller than, or equal to a limit of resolution, the laser beam is irradiated via the objective lens and a solid immersion lens having a refractive index &#x201c;n&#x201d; which is positioned between the optical recording medium and the objective lens, so that the data is recorded and readout, or is readout with respect to the optical recording medium by a recorded mark train which contains a recorded mark smaller than, equal to &#x201c;&#x3bb;&#x201d;/(4&#xb7;n&#xb7;NA).&#x201d;

Data recording and readingout system

When a space region shorter than the radius of a beam spot is formed, pre-heating with an assist pulse is not performed, and an off pulse pattern is fixed at a base power level. When a space region longer than the radius of the beam spot and shorter than the diameter of the beam spot is formed, an assist pulse is applied to the end of the space region to be formed. The length of the assist pulse is made greater, the longer the space region to be formed. Further, when a space region longer than the diameter of the beam spot is formed, an assist pulse is applied to the end of the space region to be formed, and the length of the assist pulse is kept constant regardless of the length of the space region to be formed.

Method for recording information on optical recording medium and information recording apparatus

According to the invention, a record mark is formed by: using one ON-pulse pattern and one ON-pulse pattern following it when the record mark to be formed is shorter than a specified length X (nT&#x3c;X); and using two ON-pulse patterns and two ON-pulse patterns respectively following them when the record mark to be formed is longer than the specified length X (nT&#x3e;X). This makes is possible to secure a heat amount per unit time sufficiently in forming a short record mark even when a targeted recording linear velocity is high. Also, an unwanted heat pocket becomes hard to arise in the record layer even when a sufficient heat amount per unit time is secured in forming a long record mark. Therefore, it becomes possible to form a record mark having a good shape even when data is recorded at a high linear velocity.

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Tokyo, Japan

Tatsuhiro Kobayashi