Fuji Photo Film Company, Limited

Sony Corporation

Fujifilm Corporation

Asahi Techno Glass Corporation

Nobuo Yamazaki

Shinji Saito

Hitoshi Noguchi

Hiroyuki Suzuki

Tsutomu Kume

Yoshihiro Yamamoto

Koichi Ohya

Hirotaka Takegoshi

Fumiharu Hashimoto

Hiroshi Ogawa

Masatoshi Takahashi

Tatsuji Kitamoto

Yoshiaki Matsubara

Akira Manabe

Yasuo Tamai

Hiroo Inaba

Hiroshi Yamashita

Toshio Tada

Shinya Ishii

Hiroaki Araki

Hiroaki Doushita

Kouichi Masaki

Toshihiko Miura

Koji Sasazawa

Junichi Nakamikawa

Shin-Ichiro Dezawa

Shiho Kamisawa

Hidekazu Tomizawa

Masahi Aonuma

An aspect of the present invention relates to a method of manufacturing hexagonal strontium ferrite magnetic powder, which comprises melting a starting material mixture which has a composition, as a composition converted into an oxide, lying within a region enclosed by the following four points:

Hexagonal strontium ferrite magnetic powder and method of manufacturing the same, and magnetic recording medium and method of manufacturing the same

An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on AlOconversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

Hexagonal ferrite magnetic particle and method of manufacturing the same, and magnetic recording medium

An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic powder comprising preparing a melt by melting a starting material mixture comprising a hexagonal ferrite-forming component and a glass-forming component; rapidly cooling the melt to obtain an amorphous material comprising 0.3 to 2.0 weight percent of carbon atoms; heating the amorphous material to a temperature range of 580 to 700&#xb0; C. and maintaining the amorphous material within the temperature range to precipitate hexagonal ferrite magnetic particles; and collecting the hexagonal ferrite magnetic particles precipitated.

Method of manufacturing hexagonal ferrite magnetic powder, magnetic recording medium and method of manufacturing the same

A picture display device displays a video signal supplied from a data process device. Bi-directional communication is carried out with each of a plurality of data process devices. A plurality of video signals is combined into one screen corresponding to information of the picture size of each of the plurality of video signals obtained by the bi-directional communication with each of the plurality of data process devices. A video signal, outputted when the plurality of video signals is combined, is displayed. A second control signal is generated which controls the plurality of data process devices and which corresponds to a first control signal that corresponds to a user operation. The first control signal and the second control signal are transmitted to the plurality of data process devices. The plurality of data process devices also communicate bi-directionally with each other.

Picture display device and picture display method

Provided is a magnetic recording medium exhibiting good electromagnetic characteristics in high-density recording The magnetic recording medium employed for magnetically recording signals with a track width equal to or less than 2.0 &#x3bc;m and reproducing the magnetically recorded signals, wherein said magnetic recording medium comprises a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder or comprises a nonmagnetic layer comprise a nonmagnetic powder and a binder and a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder in this order on a nonmagnetic support. Said magnetic layer has a thickness equal to or less than 0.2 &#x3bc;m, and said hexagonal ferrite ferromagnetic powder has an average plate diameter being 1/30 or less of the magnetically recorded track width as well as &#xbd; or less of the thickness of the magnetic layer.

Magnetic recording medium

A hexagonal ferrite magnetic powder having an average tabular diameter of from 15 to 28 nm, a coercive force (Hc) of from 2,000 to 5,000 Oe (from 160 to 400 kA/m), a switching field distribution (SFD) of from 0.3 to 0.7 and a D/Dof from 1.05 to 1.25. This magnetic powder can be obtained by melting and quenching starting materials to obtain an amorphous product, and thermally treating the product, which comprises increasing a temperature at a rate of 300 to 500&#xb0; C./hr in a temperature range of 550 to 600&#xb0; C. in the thermal treatment before the temperature reaches the thermally treating temperature.

Hexagonal ferrite magnetic powder, method for producing the same and magnetic recording medium

Video signals from a plurality of personal computers are written to a memory that stores video signals for a plurality of display screens through respective buffers. The video signals may be read from the respective buffers and displayed simultaneously on a single monitor. By selecting the video displayed in a portion of the monitor, the personal computer sending those video signals to the monitor may be selected for active operation. In this manner, a single set of input devices may be used to control a plurality of personal computers.

A hexagonal ferrite magnetic powder having an average tabular diameter of from 15 to 30 nm, a coercive force (Hc) of from 2,000 to 5,000 Oe (from 160 to 400 kA/m) and a saturated magnetization (&#x3c3;s) of equal to or more than the average tabular diameter (nm)&#xd7;0.37+45 A&#xb7;m/kg. This magnetic powder is obtained by melting a starting material containing a material which has a composition within the hatched region () in the triangular phase diagram shown in FIG.and quenching the molten product to obtain an amorphous product, subjecting the amorphous product to a thermal treatment, acid treatment, and washing. Also, a magnetic recording medium is obtained by adding this magnetic powder to the magnetic layer and coating it on the support.

A magnetic recording medium is disclosed, comprising a support having provided thereon a substantially nonmagnetic lower layer by coating a lower layer coating solution comprising a nonmagnetic powder dispersed in a binder and drying, and a layer having a thickness of from 0.01 to 0.15 &#x3bc;m by coating a magnetic layer coating solution comprising a ferromagnetic metal powder or a hexagonal ferrite powder dispersed in a binder, wherein the magnetic layer contains diamond particles having an average particle size of from 1/5 to 2 times the thickness of the magnetic layer in an amount of from 0.1 to 5.0 mass % based on the ferromagnetic metal powder.

Picture processing apparatus has a pixel judgment circuit and a pixel correction circuit. The pixel judgment circuit includes a target pixel detection circuit for detecting a target pixel having a peak level from the input picture signal, and an edge detection circuit for detecting edges, each present at a distance of n pixels (n&gE;1) preceding and succeeding the target pixel. Further, the pixel correction circuit has a correction coefficient selection circuit, wherein a peak level correction coefficient is selected according to an output from the target pixel detection circuit, and an edge correction coefficient is selected according to an edge detection output. With the picture processing apparatus, a level of the target pixel is corrected and an edge of the input picture signal is corrected with the pixels of the input picture signal being corrected according to the peak level correction coefficient and the edge correction coefficient.

Image processing device

A method of measuring horizontal frequency, which comprises the steps of resetting an 8-bit counter, which counts horizontal synchronous pulses separated from a video signal, at a time point corresponding to an edge of a vertical synchronous signal separated from the video signal, causing a data latch portion, which is operative to latch count data obtained from a 16-bit counter operative to count clock pulses having a predetermined frequency, to latch the count data obtained from the 16-bit counter at a time point corresponding to an edge of a bit output signal obtained from the seventh bit position of the 8-bit counter, detecting a period which corresponds to 128 times a horizontal period of the video signal based on a difference between counted values represented respectively by a couple of count data latched successively by the data latch portion, and measuring horizontal frequency of the video signal by calculating the horizontal frequency on the strength of the period corresponding to 128 times the horizontal period.

Method of and apparatus for measuring horizontal frequency

Provided is a magnetic recording medium ensuring an adequate S/N even in high density magnetic recording, and tending not to electrostatically damage MR heads during recording and reproduction employing MR heads. A magnetic recording medium comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder and a binder in this order on at least one side of a nonmagnetic support, wherein said nonmagnetic layer comprises 10 to 50 mass parts of carbon black with a mean particle diameter of 10 to 30 nm per 100 mass parts of said nonmagnetic powder, said magnetic layer has a thickness equal to or less than 0.2 &mgr;m, the standard deviation b of the average intensity a of elements due to said ferromagnetic powder as determined by electron-beam microanalysis is 0.03&lE;b/a&lE;0.4, and said magnetic layer has a center surface average roughness Ra equal to or less than 5 nm and a ten-point average roughness Rz equal to or less than 50 nm.

Provided are a method of magnetic recording and reproducing capable of permitting high density recording on magnetic recording media even under the condition of high data transfer rates and yielding adequate recording and reproduction characteristics when an MR head is used in reproduction, and a magnetic recording medium capable of being used in this magnetic recording and reproducing method. The magnetic recording and reproducing method is a method for reproducing a signal magnetically recorded on a magnetic recording medium with a magnetoresistive (MR) head. The magnetic recording medium comprises a substantially nonmagnetic lower layer and a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder in this order on at least one side of a nonmagnetic support, in which said hexagonal ferrite ferromagnetic powder has a mean plate diameter ranging from 15 to 40 nm and a mean plate thickness ranging from 4 to 15 nm, and said magnetic layer has a coercive force Hc ranging from 143.3 to 318.4 kA/m, and said signal magnetically recorded has a maximum recording frequency ranging from 10 to 80 MHz.

Growing community of inventors

Kanagawa, Japan

Nobuo Yamazaki