884 results about "Recording density" patented technology

An information processor of a high reliability and a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, used for the same, are provided. An optical information processor of a high reliability and a high recording density enables a moving picture, such as a high-definition television picture, to be recorded and reproduced satisfactorily. A barrier layer in a quantum-well active layer of a semiconductor light emitting device is doped with n-type impurities at a high density. Alternatively, the face orientation of a quantum-well active layer of a semiconductor light emitting device is a plane inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be decreased. The semiconductor light emitting device is typified by a gallium nitride based compound semiconductor laser device.

It is an object to manufacture magnetic recording media with the high recording density. Since nonmagnetic portions (8) with a predetermined pattern are formed in a recording auxiliary layer (4) formed on a magnetic recording layer (3), it is possible to actualize a magnetic recording medium where magnetic portions (7) and the magnetic recording layer (3) immediately below the portions (7) are recording units. The nonmagnetic portions (8) are formed by non-magnetization using ion implantation, and it is thereby possible to manufacture magnetic recording media with the high recording density.

A method for recording information on a recording medium utilizing an interference pattern by interference between an information light modulated spatially with digital pattern information displayed on a spatial light modulator having multiple pixels and a reference light for recording. In order to provide a novel recording method capable of enhancing the recording density and the transfer rate furthermore, digital information to be recorded is represented by match / mismatch of the attributes of adjacent pixels in the spatial light modulator to produce digital pattern information.

A characteristic evaluation method of a perpendicular magnetic recording medium suitable for obtaining a perpendicular magnetic recording medium which can respond to much higher recording density is provided.This is an evaluation method of a perpendicular magnetic recording medium, including a process of recording a first signal of a specific frequency at an arbitrary first position in the perpendicular magnetic recording medium; a process of measuring a reproduction output of the first signal and of measuring a signal / noise ratio (initial value) of the first signal at a peak position where the reproduction output becomes the maximum; a process of recording a signal of a specific frequency at a second position away from the first position by a predetermined distance in the radial direction of the perpendicular magnetic recording medium; a process of measuring the signal / noise ratio of the first signal at the peak position again; a process of repeating the process of recording the signal of the specific frequency at a position brought close to the first position from the second position by a predetermined distance and of measuring the signal / noise ratio of the first signal at the peak position again while sequentially getting closer to the first position from the second position; and a process of determining whether the value of the signal / noise ratio has lowered from the initial value by a predetermined range or more.

[PROBLEMS] To provide a process for producing a magnetic recording medium, which can simultaneously realize increased high recording density, high impact resistance, and prevention of corrosion, by providing an underlayer which, even when formed at a low gas pressure, can exhibit a high level of coercive force.[MEANS FOR SOLVING PROBLEMS] A process for producing a perpendicular magnetic recording medium, comprising the step of forming a nonmagnetic underlayer (18) having a granular structure, in which crystal particles are grown in a column form, on a substrate, and forming a magnetic recording layer (20) having a granular structure in which magnetic particles are grown in a column form. The process is characterized in that the underlayer (18) is any one of CoCr or CoCrX (wherein X is a nonmagnetic material), CoCr-oxide, and CoCrX-oxide, and the film forming gas pressure of the underlayer (18) is not more than 4 Pa.

The present invention provides a perpendicular magnetic recording medium that can reduce noise by further size reduction and isolation of magnetic grains in a magnetic recording layer and can increase the recording density by improvement of the SNR. A typical configuration of a perpendicular magnetic recording medium according to the present invention is a perpendicular magnetic recording medium having a magnetic recording layer with a granular structure in which non-magnetic grain boundary portions are formed between magnetic grains that have grown continuously in a columnar shape, wherein the grain boundary portions contain a plurality of kinds of oxides.