Magnetic Feature Patents (Class 428/900)
  • Patent number: 6287663
    Abstract: There is provided a glass-ceramic substrate for a magnetic information storage medium having a data zone and a landing zone capable of stably lifting a magnetic head in the landing zone and also capable of reducing the amount of lifting of the magnetic head in the data zone for realizing a high recording density. The landing zone has a multiplicity of projections or depressions formed by irradiation of laser beam. A CO2 laser or a laser diode pumped solid-state laser can be used for this purpose. The surface roughness (Ra) of a polished surface of the landing zone is within a range from 3 Å to 9 Å, height of the projections or depressions is within a range from 50 Å to 300 Å, surface roughness (Ra) of the projections or depressions is within a range from 10 Å to 50 Å and interval of the projections or depressions is within a range from 10 &mgr;m to 200 &mgr;m.
    Type: Grant
    Filed: November 25, 1996
    Date of Patent: September 11, 2001
    Assignee: Kabushiki Kaisha Ohara
    Inventor: Naoyuki Goto
  • Patent number: 6287668
    Abstract: A magnetic recording medium of the present invention comprises: a non-magnetic base film; a non-magnetic undercoat layer formed on said non-magnetic base film, comprising a binder resin and non-magnetic acicular black iron-based composite particles; and a magnetic coating film comprising a binder resin and magnetic particles, said non-magnetic acicular black iron-based composite particles comprising: acicular hematite particles or acicular iron oxide hydroxide particles having an average major axis diameter of 0.02 to 0.30 &mgr;m; a coating layer formed on the surface of said acicular hematite particle or acicular iron oxide hydroxide particle, comprising a specific organosilicon compound; and a carbon black coat formed on said coating layer. Such a magnetic recording medium has a more smooth surface, a high strength and a lower light transmittance and a low electric resistance even at a small carbon black content.
    Type: Grant
    Filed: March 10, 2000
    Date of Patent: September 11, 2001
    Assignee: Toda Kogyo Corporation
    Inventors: Kazuyuki Hayashi, Keisuke Iwasaki, Yasuyuki Tanaka, Hiroko Morii
  • Patent number: 6284352
    Abstract: A low cost, reusable electric paper that uses ferrofluidic colored fluids and an external magnetic writing instrument. The paper can be formed from laminated rolls of polymeric media that are roller die cut, inked, aligned, bonded and cut to an appropriate size. The paper is formed from layers that define a hidden reservoir and a visible reservoir for each of an array of print cells that form a grid on the paper. A ferrofluidic coloring fluid is permanently contained within the paper and can move from the hidden reservoir to the visible reservoir. The size of the cells define the resolution of the paper. Initially, the paper appears white. However, after passing a writing instrument, such as a stylus, over desired print cells, these cells switch from a first hidden bistable state to a second visible bistable state. In the second visible bistable state, the ferrofluidic coloring fluid forms a desired image in a desired color or colors.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: September 4, 2001
    Assignee: Xerox Corporation
    Inventors: David Kalman Biegelsen, Warren Bruce Jackson
  • Patent number: 6284361
    Abstract: A magnetic recording medium comprising a substrate having provided thereon at least one intermediate layer essentially containing nonmagnetic powder and a binder and further having thereon a magnetic layer as an upper layer which essentially contains ferromagnetic powder and a binder, wherein the nonmagnetic powder in the intermediate layer is mainly acicular, and the acicular nonmagnetic powder has a coefficient of orientation (&agr;) of 0 to 0.8 in the longitudinal direction in the surface thereof.
    Type: Grant
    Filed: October 27, 1998
    Date of Patent: September 4, 2001
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Hideyuki Kobayashi, Kazutaka Yamashita, Masayasu Sato
  • Patent number: 6284340
    Abstract: A crystallized glass has a main crystal phase of petalite (Li2O.Al2O3.8SiO2) phase and lithium disilicate (Li2O.2SiO2) phase and an auxiliary crystal phase of &agr;-quartz phase. In the crystallized glass, a crystal phase composition measured by Rietvelt method is as follows: 20 wt %≦petalite phase≦40 wt %, 25 wt %≦lithium disilicate phase≦45 wt %, and 10 wt %≦&agr;-quartz phase≦25 wt %.
    Type: Grant
    Filed: September 26, 2000
    Date of Patent: September 4, 2001
    Assignee: NGK Insulators, Ltd.
    Inventors: Masahiro Abe, Takahiro Takahashi
  • Patent number: 6281774
    Abstract: The present invention provides an Fe—B—R based permanent magnet, which has a chemical conversion coating film formed on its surface with an aluminum film interposed therebetween, the chemical conversion coating film containing at least one of titanium and zirconium, phosphorus, oxygen and fluorine as constituting elements, and a process for producing such an Fe—B—R based permanent magnet. In the permanent magnet, the chemical conversion coating film is adhered firmly to the magnet with the aluminum film interposed therebetween and hence, the magnet is excellent in corrosion resistance. Even if the magnet is left to stand for a long time under high-temperature and high-humidity conditions of a temperature of 80° C. and a relative humidity of 90%, the magnet exhibits a stable high magnetic characteristic which cannot deteriorate. Moreover, the film is free from hexa-valent chromium.
    Type: Grant
    Filed: May 9, 2000
    Date of Patent: August 28, 2001
    Assignee: Sumitomo Special Metals Co., Ltd.
    Inventors: Takeshi Nishiuchi, Kohshi Yoshimura, Fumiaki Kikui
  • Patent number: 6277484
    Abstract: A magnetic recording medium using a substrate, such as a glass substrate, and having, in combination, superior magnetic and magnetic recording properties and good adhesion of a magnetic layer to the substrate. The magnetic recording medium has an intermediate layer of chromium between the substrate and an underlayer of Ni-based non-magnetic material on which a magnetic layer of Co-based magnetic alloy is superimposed. A method of producing the magnetic recording medium is also disclosed, wherein each of the layers is formed by a sputtering process at a sufficient pressure to promote granular growth of crystals of the layer.
    Type: Grant
    Filed: October 7, 1998
    Date of Patent: August 21, 2001
    Assignee: Fujitsu Limited
    Inventors: Kazumasa Shimoda, Ryoichi Mukai, Hiroto Takeshita
  • Patent number: 6277505
    Abstract: A structure which includes a ferromagnetic (FM) layer, a thin oxide layer, and an antiferromagnetic (AFM) layer is provided. The thin oxide layer, between 1 to 10 oxygen atoms in thickness, minimizes interlayer atomic diffusion between the FM layer and the antiferromagnetic layer. In a preferred embodiment, a spin valve sensor with improved thermal stability is provided by including the thin oxide layer between a FM layer and an AFM layer. The presence of the thin oxide layer also results in an improved spin valve sensor with an enhanced exchange pinning field.
    Type: Grant
    Filed: January 21, 1999
    Date of Patent: August 21, 2001
    Assignee: Read-Rite Corporation
    Inventors: Zhupei Shi, Ming Mao, Qunwen Leng
  • Patent number: 6277465
    Abstract: In a magnetic recording medium, surface roughness of a glass substrate and the variation of the surface roughness are suppressed. Namely, the surface roughness (Rmax, Ra, Rq) and the relation (Rmax/Ra) between Rmax and Ra are restricted. Ra is representative of a center-line mean roughness, Rmax is defined as a maximum height representative of a difference between a highest point and a lowest point and Rq is representative of a root mean square roughness. Thereby, crystal grains of an underlying layer and a magnetic layer formed thereon are equalized. The surface roughness is specified by Rmax≦15 nm, Ra≦1 nm and Rq≦1.5 nm and the ratio between the surface roughness Rmax and the surface roughness Ra is in the range of 10 to 30.
    Type: Grant
    Filed: December 29, 1997
    Date of Patent: August 21, 2001
    Assignee: Hoya Corporation
    Inventors: Tsuyoshi Watanabe, Koji Takahashi, Masao Takano
  • Patent number: 6274256
    Abstract: A product (S×Bs) of a cross-sectional area of a tip portion of an upper core layer (S) (a thickness of a layer d1 by a track width Tw) and a saturation magnetic flux density thereof (Bs) is in a range of 1.5 to 10.5 &mgr;m2·T, and preferably in a range of 4.0 to 8.0 &mgr;m2·T. Further, a magnetic pole straight length L1 ranges from 3.5 to 7.6 &mgr;M. Thus, excellent NLTS and OW characteristics can be simultaneously obtained.
    Type: Grant
    Filed: February 1, 1999
    Date of Patent: August 14, 2001
    Assignee: Alps Electric Co., Ltd.
    Inventors: Toshinori Watanabe, Atsushi Sato, Akira Takahashi
  • Patent number: 6274233
    Abstract: A magnetic recording medium comprising a substrate 1 having thereon an in-plane magnetic film 3 having a magnetic easy axis oriented in the in-plane direction with respect to the substrate and a vertical magnetic film 6 having a magnetic easy axis oriented perpendicularly to the substrate. The in-plane magnetic film 3 is disposed closer to the substrate 1 than the vertical magnetic film 6. In preferred embodiments, the magnetic recording medium may further comprise a separation film 4 disposed between the in-plane magnetic film 3 and the vertical magnetic film 6, a nonmagnetic intermediate layer 5 having an hcp structure disposed between the separation film 4 and the vertical magnetic film 6, and a protective film 7. The magnetic recording medium is adapted for use with a signal processing system generally used for in-plane magnetic recording media without modification of the signal processing system.
    Type: Grant
    Filed: March 25, 1999
    Date of Patent: August 14, 2001
    Assignees: Showa Denko Kabushiki Kaisha, Waseda University
    Inventors: Toshihiko Yoshikawa, Akira Sakawaki, Hiroshi Sakai, Tetsuya Osaka
  • Patent number: 6274220
    Abstract: The present invention provides aromatic polyamide resin moldings comprising at least one surface that is 1.0 nm or more in root-mean-square roughness and is 80 nm or less in 10-point average roughness, both of the roughness being as determined by atomic force microscopy, and that is 9.8 GPa or more in tensile Young's modulus at least in one direction. Such aromatic polyamide resin moldings serve effectively as material for film, film for magnetic recording medium in particular, that is highly resistant to scraping and has highly uniform surface protrusions.
    Type: Grant
    Filed: April 28, 1998
    Date of Patent: August 14, 2001
    Assignee: Toray Industries, Inc.
    Inventors: Akimitsu Tsukuda, Masanori Sueoka, Toshihiro Tsuzuki
  • Patent number: 6274222
    Abstract: An object of the invention is to increase the number of thin-film magnetic heads obtained. In a wafer a plurality of rows of head-to-be sections to be thin-film magnetic heads are aligned. The wafer includes: an inter-row cutting section provided to be a position at which adjacent ones of the rows are to be separated; and an intra-row cutting section provided to be a position at which adjacent ones of the head-to be sections in each of the rows are to be separated. In the wafer a detection element for detecting an amount of processing is formed near the medium-facing surface-side end of the intra-row cutting section. An electrode for monitoring is formed in the inter-row cutting section in the wafer for electrically connecting the detection element to an external device. Furthermore, a lead for monitoring is formed in the intra-row cutting section for electrically connecting the electrode to the detection element.
    Type: Grant
    Filed: September 7, 1999
    Date of Patent: August 14, 2001
    Assignee: TDK Corporation
    Inventors: Yoshitaka Sasaki, Hiroyuki Itoh
  • Patent number: 6274223
    Abstract: A magnetic recording medium incorporating a backcoat layer which exhibits excellent movement characteristics, the magnetic recording medium having a non-magnetic support member; a magnetic layer formed on either surface of the non-magnetic support member and mainly composed of magnetic powder and a binder; and a backcoat layer formed on another surface of the non-magnetic support member and structured such that non-magnetic powder is dispersed in a binder, wherein the backcoat layer contains the non-magnetic powder composed of carbon black and inorganic powder having Moh's hardness of 6 to 9 at a ratio of 90:10 to 85:15, the contained binder is made of phenoxy resin, polyurethane resin and nitrocellulose, the contained carbon black consists of carbon black having an average primary particle size of 25 nm to 55 nm and carbon black having an average primary particle size of 280 nm to 350 nm and the contained inorganic powder consists of inorganic powder having an average primary particle size of 260 nm to
    Type: Grant
    Filed: March 1, 2000
    Date of Patent: August 14, 2001
    Assignee: Sony Corporation
    Inventor: Muneharu Odaira
  • Patent number: 6274387
    Abstract: A novel magnetic carrier is provided which comprises particulate silica containing a magnetic material, having polyacrylamide on the surface thereof in an amount ranging from 0.3 to 5 mmol/g in terms of monomeric acrylamide. A process for producing the magnetic carrier is also provided in which the surface of particulate silica containing a magnetic material is treated with a coupling agent, and the treated particulate silica is reacted with acrylamide and/or polyacrylamide. The magnetic carrier is useful for extraction of nucleic acid. The magnetic carrier can be produced readily by controlling the shape, the particle diameter, and the pore diameter, and is excellent in strength and adsorption efficiency. The extraction of a nucleic acid can be automated by use of the magnetic carrier.
    Type: Grant
    Filed: December 28, 1998
    Date of Patent: August 14, 2001
    Assignee: Tosoh Corporation
    Inventors: Syoichi Yamauchi, Kiyoshi Kasai
  • Patent number: 6274227
    Abstract: A magnetic recording medium comprising a nonmagnetic substrate, a liquid lubricant-containing coating layer having a porosity (U) formed on the substrate, and a magnetic layer having a porosity (M) formed directly on the coating layer. The ratio of porosity (U/M) between the coating and magnetic layers is between 0.75 and 1.25. The volume percentage of the lubricant contained in the pores of the coating layer based on the whole pore volume in the coating layer is from 35 to 85%. This improves the durability of the magnetic layer.
    Type: Grant
    Filed: September 24, 1999
    Date of Patent: August 14, 2001
    Assignee: Imation Corp.
    Inventors: Shigeto Oiri, Yoji Tsukamoto, Hideaki Yasui
  • Patent number: 6270885
    Abstract: In a perpendicular magnetic recording medium, a soft magnetic film playing the role of an back layer, but not having a domain wall structure, is positioned beneath a perpendicular magnetization film. Such a back layer improves the envelope characteristic of the medium at the time of recording and reproduction. Moreover, the medium is free from spike noise and the decrease or cancellation of recorded magnetization ascribable to the movement of the domain wall of a back layer. The medium of the present invention is therefore a drastic solution to the problems particular to a conventional perpendicular magnetic recording medium and realizes desirable recording and reproducing characteristics.
    Type: Grant
    Filed: November 17, 1998
    Date of Patent: August 7, 2001
    Assignee: NEC Corporation
    Inventors: Hirotaka Hokkyo, Shinzo Tsuboi, Katsumichi Tagami
  • Patent number: 6268043
    Abstract: A magnetic recording medium which is capable of improving durability and reliability while satisfactory electromagnetic conversion characteristics are being maintained, the magnetic recording medium incorporating a non-magnetic support member; and a magnetic layer formed on the non-magnetic support member and mainly composed of magnetic powder and a binder and having a two-layer structure composed of a first magnetic layer and a second magnetic layer, wherein Young's modulus of the first magnetic layer is 140×105 N/m2 to 160×105 N/m2 and Young's modulus of the second magnetic layer is 45×105 N/m2 to 50×105 N/m2. The specific surface area of the magnetic powder for use in the first magnetic layer is 42 m2/g to 46 m2/g and the specific surface area of the magnetic powder for use in the second magnetic layer is 32 m2/g to 35 m2/g.
    Type: Grant
    Filed: February 16, 2000
    Date of Patent: July 31, 2001
    Assignee: Sony Corporation
    Inventors: Takeshi Koizumi, Miwako Sato, Norio Adachi
  • Patent number: 6268036
    Abstract: A improved thin film recording medium with an underlayer with deliberately induced strain, crystalline defects and dislocations (collectively “faults”) in the grain structure is described. The relatively high number of induced faults results in surprising improvements in recording characteristics such as soft error rate, resolution and SNR of the thin film disk. While the film is being deposited, the sputtering conditions are controlled to grow grains of the underlayer material which tend to be highly faulted by incorporation of atoms of a second material with significantly different atomic characteristics than the underlayer material. Preferably the atoms of the sputtering gas species are incorporated in the film to cause the lattice faults. For example, the faults can be achieved by incorporating sputtering gas atoms, e.g. argon atoms, into a chromium based underlayer.
    Type: Grant
    Filed: June 26, 1998
    Date of Patent: July 31, 2001
    Assignee: International Business Machines Corporation
    Inventors: Ernesto Esteban Marinero, Timothy Martin Reith, Brian Rodrick York
  • Patent number: 6265062
    Abstract: A magnetic recording medium comprising first, second and third magnetic layers laminated in succession, wherein when (1) the magnetic wall energy density, saturation magnetization, magnetic wall coercivity and film thickness of the first magnetic layer at a temperature T represented by cgs unit system are defined as &sgr;1, Ms1, Hw1 (2) h1, respectively, and the magnetic wall energy density, saturation magnetization, magnetic wall coercivity and film thickness of the third magnetic layer are defined as &sgr;3, Ms3, Hw3 and h3, respectively, (3) the interface magnetic wall energy density between the first magnetic layer and the third magnetic layer is defined as &sgr;w13, and (4) the lowest temperature at which &sgr;w13 is 0 erg/cm2 is Ts, at least 2Ms1*Hw1<&sgr;w13/h1  and 2Ms3*Hw3>&sgr;w13/h3  are satisfied, at room temperature and when a suitable temperature Tp is chosen, within a temperature range greater than the temperature Ts and lower by 10° C.
    Type: Grant
    Filed: September 18, 1997
    Date of Patent: July 24, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventor: Tsutomu Shiratori
  • Patent number: 6265060
    Abstract: A magnetic recording medium, comprising a magnetic layer provided on a nonmagnetizable substrate, wherein the magnetic layer comprises a magnetic pigment dispersed in a polymeric binder, the polymeric binder comprising a resin, wherein the resin comprises a nonchlorinated fluorine-containing vinyl copolymer having pendant nitrile groups, pendant hydroxyl groups, and pendant fluorine-containing groups.
    Type: Grant
    Filed: March 15, 1995
    Date of Patent: July 24, 2001
    Assignee: Imation Corp.
    Inventors: Ravindra L. Arudi, Ramesh C. Kumar
  • Publication number: 20010008702
    Abstract: Large, unique decorations using flexible magnetic material which would magnetically adhere to any ferrous surface such as patio furniture, doors, garage doors, storage buildings, recreational vehicles, mobile homes, file cabinets, desks and the like. The invention would consist of various methods of applied graphics, such as screen or digital printing, for both seasonal and non-seasonal decorations.
    Type: Application
    Filed: March 9, 2001
    Publication date: July 19, 2001
    Inventor: Janet Hibbs Vela
  • Patent number: 6261681
    Abstract: A magnetic recording medium comprising a non-ferromagnetic substrate and a magnetic recording film formed on the substrate with an underlayer interposed therebetween, wherein the magnetic recording film comprises a plurality of magnetic layers and an interlayer made of a material having a B2 crystal structure or an interlayer made of Ru, disposed between the adjacent magnetic layers.
    Type: Grant
    Filed: March 10, 1999
    Date of Patent: July 17, 2001
    Assignee: Asahi Komag Co., Ltd.
    Inventors: Michinobu Suekane, Makoto Imakawa, Takehiko Hiruma
  • Patent number: 6261707
    Abstract: A magneto-optical recording medium is composed of a base which has a property that a light can be transmitted therethrough, a readout layer formed on the base, which has in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as the temperature thereof is raised and a recording layer formed on the readout layer for recording information magneto-optically. A recording and reproducing method and the optical head are designed for the magneto-optical recording medium. By the recording and reproducing method using the optical head, information recorded at high density can be reproduced.
    Type: Grant
    Filed: November 3, 1993
    Date of Patent: July 17, 2001
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshiteru Murakami, Junji Hirokane, Junichiro Nakayama, Junsaku Nakajima, Akira Takahashi, Kenji Ohta, Naoyasu Iketani
  • Patent number: 6258470
    Abstract: An exchange coupling film of the present invention includes a ferromagnetic layer and a pinning layer which is provided in contact with the ferromagnetic layer for pinning a magnetization direction of the ferromagnetic layer, the pinning layer including an (AB)2Ox layer, wherein: O denotes an oxygen atom; 2.8<x<3.2; and a value t as defined by: t=(Ra+Ro)/({square root over (2)}·(Rb+Ro)) (where Ra, Rb and Ro denote the ion radii of the atoms A, B and O, respectively) satisfies 0.8<t<0.97.
    Type: Grant
    Filed: January 12, 1999
    Date of Patent: July 10, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroshi Sakakima, Eiichi Hirota, Yasuhiro Kawawake, Mitsuo Satomi, Yasunari Sugita
  • Patent number: 6258442
    Abstract: A biaxially oriented polyester film for a magnetic recording medium, which comprises an aromatic polyester resin composition comprising: (A) an aromatic polyester, (B) silicone resin particles which can be obtained by polymerizing a silane compound containing trialkoxysilane in the presence of a surfactant and water, contain at least 80 wt % of recurring units and are substantially spherical, and (C) other inert fine particles. This biaxially oriented polyester film for a magnetic recording medium has an extremely small number of coarse protrusions and excellent winding property, abrasion resistance and traveling durability and can be produced at a low production cost.
    Type: Grant
    Filed: March 3, 1999
    Date of Patent: July 10, 2001
    Assignee: Teijin Limited
    Inventors: Tatsuya Ogawa, Hideaki Watanabe, Manabu Kimura
  • Patent number: 6258434
    Abstract: A magnetic recording medium having a diamond-like carbon (DLC) film added therein a Group IV element of the periodic table such as silicon, particularly in the vicinity of the boundary between the magnetic material and the formed DLC film. Since a DLC having low friction coefficient can be formed, the centerline average roughness can be reduced to 30 nm or even less. Accordingly, a magnetic recording medium improved in magnetic properties and in lubricity can be obtained.
    Type: Grant
    Filed: September 29, 1999
    Date of Patent: July 10, 2001
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventor: Shigenori Hayashi
  • Patent number: 6255006
    Abstract: A magnetic recording medium comprising a non-magnetic substrate having thereon a non-magnetic undercoat, a magnetic film and optionally a protective film. The magnetic film comprises a material containing Co as a main component. The non-magnetic undercoat comprises at least two layers including a first undercoat film and a second undercoat film provided on the first undercoat film. The first undercoat film comprises a material containing Cr as a main component, and the second undercoat film comprises a material selected from the group consisting of a Cr/Nb-base alloy, a Cr/W-base alloy, a Cr/V-base alloy and a Cr/Mo-base alloy as a main component.
    Type: Grant
    Filed: January 8, 1999
    Date of Patent: July 3, 2001
    Assignee: Showa Denko Kabushiki Kaisha
    Inventors: Kazunori Ohnami, Hiroshi Kanazawa, Hiroshi Sakai
  • Patent number: 6255477
    Abstract: Magnetic glass particles are prepared containing a magnetic core coated with a glass layer having a substantially pore-free glass surface. The particles are used for separating biological material such as nucleic acids. A preferred process of preparing the particles is by forming a mixture of magnetic cores with a sol formed from an alcohol and a metal alkoxide, spray-drying the mixture to coat the cores with a layer of gelled sol, and heating the coated cores to obtain the magnetic glass particles. Preferably, the particles have an average particle size of less than 100 &mgr;m and any pores of the glass surface have a diameter of less than 10 nm. The magnetic core may be a composite material containing a mica core and magnetite particles immobilized on the mica core, and the glass layer may contain boron oxide. Magnetic core materials include magnetite (Fe3O4) and Fe2O3.
    Type: Grant
    Filed: March 11, 1998
    Date of Patent: July 3, 2001
    Assignee: Roche Diagnostics GmbH
    Inventors: Jörg Kleiber, Thomas Walter, Herbert Harttig, Christoph Lesniak, Martin Mennig, Michael Riedling, Helmut Schmidt
  • Patent number: 6255005
    Abstract: Provided is a composite magnetic member made of a single material combining a ferromagnetic portion and a non-magnetic portion in which the ferromagnetic portion has better soft magnetism than conventional members and the non-magnetic portion has the same stable characteristic as conventional members. A method of producing the ferromagnetic portion of the member and a method of forming the non-magnetic portion are also provided. The composite magnetic member is made of an Fe—Cr—C-base alloy steel containing 0.1 to 5.0 weight % Al and has a ferromagnetic portion with a maximum magnetic permeability of not less than 400 and a non-magnetic portion with a magnetic permeability of not more than 2. In this member the number of carbides with a grain size of not less than 0.1 &mgr;m is regulated to not more than 50 in an area of 100 &mgr;m2 and the proportion of the number of carbides with a grain size of not less than 1.0 &mgr;m to the number of all carbides is controlled to not less than 15%.
    Type: Grant
    Filed: July 22, 1999
    Date of Patent: July 3, 2001
    Assignee: Hitachi Metals, Ltd.
    Inventors: Shin-ichiro Yokoyama, Tsutomu Inui, Hideya Yamada
  • Patent number: 6251496
    Abstract: A method for producing a magnetic recording medium includes the steps of causing a polymer film having a vapor-deposition surface to run; vaporizing a ferromagnetic metal material; depositing a thin film including the ferromagnetic metal material to the vapor-deposition surface of the polymer film in a vapor-deposition area where the polymer film runs with a tilt angle, with respect to a horizontal direction, in the range of about 20 degrees or more and about 80 degrees or less by oblique vapor deposition.
    Type: Grant
    Filed: December 24, 1998
    Date of Patent: June 26, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Yoshiharu Maezawa
  • Patent number: 6251509
    Abstract: A magnetic tape favorably employable for recording computer data has a support, and on one side of the support, a essentially non-magnetic layer composed of a non-magnetic powder and a binder, and a magnetic layer composed of a ferromagnetic powder and a binder superposed in order, and on the other side, a back-coating layer containing carbon black, wherein the magnetic layer has a thickness of 0.08 to 0.28 &mgr;m and a magnetic flux of 0.02 to 0.1 G·cm.
    Type: Grant
    Filed: February 23, 1999
    Date of Patent: June 26, 2001
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Toshio Kawamata, Toshiyuki Kitahara, Minoru Sueki
  • Patent number: 6251230
    Abstract: A method and a device for manufacturing a thin film by a vacuum deposition method, and a magnetic recording medium produced thereby are disclosed. A thin film of high quality is mass-produced while introducing reaction gas to a thin film forming section from a nozzle consisting of minute tubes, so that the flow of evaporated atoms is not disturbed by the reaction gas.
    Type: Grant
    Filed: February 11, 2000
    Date of Patent: June 26, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kazuyoshi Honda, Yoshiharu Maezawa, Masaru Odagiri, Sadayuki Okazaki
  • Patent number: 6248439
    Abstract: A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced thereby improving a reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher.
    Type: Grant
    Filed: January 4, 1995
    Date of Patent: June 19, 2001
    Assignee: Fujitsu Ltd.
    Inventors: Ken Tamanoi, Keiji Shono, Sumio Kuroda, Motonobu Mihara, Koji Matsumoto
  • Patent number: 6248437
    Abstract: The present invention relates to acicular hematite particles containing aluminum of 0.05 to 50% by weight, calculated as Al, having an average major axial diameter of not more than 0.3 &mgr;m and a pH value of the particles of not less than 8, and containing soluble sodium salts of not more than 300 ppm soluble sodium, calculated as Na, and soluble sulfates of not more than 150 ppm soluble sulfate, calculated as SO4, which have an excellent dispersibility in a binder resin, and a magnetic recording medium which uses the hematite particles as non-magnetic particles for a non-magnetic undercoat layer, which has small light transmittance, smooth surface, high strength and high durability, and which is capable of suppressing the deterioration in the magnetic properties caused by a corrosion of the magnetic particles containing as a main ingredient in the magnetic recording layer.
    Type: Grant
    Filed: May 23, 2000
    Date of Patent: June 19, 2001
    Assignee: Toda Kogyo Corporation
    Inventors: Kazuyuki Hayashi, Keisuke Iwasaki, Hiroko Morii, Yasuyuki Tanaka
  • Patent number: 6245450
    Abstract: An exchange coupling film of the present invention includes a substrate and a multilayer film. The multilayer film includes: a ferromagnetic layer and a magnetization rotation suppressing layer provided adjacent to the ferromagnetic layer for suppressing a magnetization rotation of the ferromagnetic layer; and the magnetization rotation suppressing layer includes an Fe—M—O layer (where M=Al, Ti, Co, Mn, Cr, Ni or V).
    Type: Grant
    Filed: January 25, 1999
    Date of Patent: June 12, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yasuhiro Kawawake, Hiroshi Sakakima, Mitsuo Satomi, Yasunari Sugita
  • Patent number: 6245417
    Abstract: A magnetic recording medium is provided with multilayered carbon-containing protective overcoats having different surface polarities and electrical conductivities, thereby enabling optimum performance to be tailored for different drive programs. Embodiments include a first protective overcoat comprising hydrogenated carbon and a second protective overcoat comprising graphitic carbon or amorphous carbon nitride.
    Type: Grant
    Filed: April 21, 1998
    Date of Patent: June 12, 2001
    Assignee: Seagate Technology LLC
    Inventor: Liji Huang
  • Patent number: 6245441
    Abstract: This is a composite magnetic member excellent in corrosion resistance having a chemical composition consisting essentially, by weight, of 0.30 to 0.80% C, more than 16.0% but not more than 25.0% Cr, 0.1 to 4.0% Ni, 0.1 to 0.06% N, at least one kind not more than 2.0% in total selected from the group consisting of Si, Mn and Al, and the balance Fe and impurities, and having a ferromagnetic portion and a non-magnetic portion.
    Type: Grant
    Filed: June 18, 1999
    Date of Patent: June 12, 2001
    Assignees: Hitachi Metals, Ltd., Denso Corporation
    Inventors: Shin-ichiro Yokoyama, Tsutomu Inui, Yoshihiro Tanimura
  • Patent number: 6245411
    Abstract: A high rigidity glass-ceramic substrate for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. Predominant crystal phases of the glass-ceramic substrate consist of (1) cordierite or cordierite solid solution and (2) one or more crystals selected from the group consisting of Spinel crystal, Spinel crystal solid solution, enstatite, enstatite solid solution, &bgr;-quartz and &bgr;-quartz solid solution.
    Type: Grant
    Filed: November 30, 1998
    Date of Patent: June 12, 2001
    Assignee: Kabushiki Kaisha Ohara
    Inventors: Naoyuki Goto, Kousuke Nakajima, Junko Ishioka
  • Patent number: 6242085
    Abstract: An underlying layer is formed of Cr or the like on a glass substrate, and a magnetic layer is formed on the underlying layer by simultaneously sputtering a magnetic substance and a non-magnetic substance that does not form a solid solution with the magnetic substance in an atmosphere having a pressure of 30 mTorr to 75 mTorr. The magnetic recording medium comprises clusters, each of which is formed of aggregated magnetic grains, and a non-magnetic substance between the clusters. Each magnetic grain has a grain diameter of 5 nm to 20 nm. An average gap between the clusters is 1.5 nm to 5 nm. Thus, the present invention can provide a magnetic recording medium having a high S/N ratio that is suitable for high density recording.
    Type: Grant
    Filed: September 15, 1998
    Date of Patent: June 5, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroshi Ryonai, Tatsuaki Ishida, Kiyokazu Tohma, Keizou Miyata, Taizou Hamada
  • Patent number: 6242086
    Abstract: High areal density magnetic recording media are formed with a thin CoCrTaOx intermediate layer which provides appropriate crystalline orientation and surface morphology for the nucleation and growth of a magnetic layer thereon having increased coercivity and high squareness, while avoiding high substrate heating temperatures. Embodiments include sputter depositing an intermediate layer comprising Co, about 10 to about 20 atomic % Cr and about 1 to about 6 atomic % Ta, at a thickness of about 1.5 to about 18 Å on a Cr or Cr alloy underlayer, allowing partial oxidation of the surface of the intermediate layer by residual oxygen in the sputtering system, and then sputter depositing a CoCrPtTa magnetic alloy layer thereon.
    Type: Grant
    Filed: November 10, 1998
    Date of Patent: June 5, 2001
    Assignee: Seagate Technology LLC
    Inventors: Xing Song, Qixu Chen, Charles Leu, Rajiv Yadav Ranjan
  • Patent number: 6238809
    Abstract: The Hr and SNR of a magnetic recording medium are increased and reduced recording signal modulation by employing an underlayer containing Cr or a Cr alloy with Ta2O5 dispersed therein. Embodiments include a composite underlayer comprising a first Cr or Cr alloy underlayer containing about 0.1 to about 10 at. % dispersed Ta2O5 and a second underlayer comprising Cr or a Cr alloy, e.g. CrV, thereon.
    Type: Grant
    Filed: September 25, 1998
    Date of Patent: May 29, 2001
    Assignee: Seagate Technology LLC
    Inventors: Zhong Stella Wu, Rajiv Y. Ranjan
  • Patent number: 6238796
    Abstract: A thin-film magnetic recording disc for use with a read/write head in a disc drive includes a substrate, a magnetic recording film disposed over the substrate, and a protective overcoat on the recording film. The recording disc has an outer layer that includes a solid fluorocarbon and a perfluoropolyether (PFPE) oil. The disc can be used as a data storage media for a digital computer and, in particular, with a read/write head in a disc drive. The addition of the fluorocarbon layer can improve the tribology of the disc, thereby reducing wear and improving the long-term performance of the magnetic disc.
    Type: Grant
    Filed: October 27, 1998
    Date of Patent: May 29, 2001
    Assignee: Seagate Technology LLC
    Inventors: Youmin Liu, Vidyadhara K. Gubbi, Chung Y. Shih
  • Patent number: 6235368
    Abstract: A magnetic recording medium which consists of at least two layers cast one on top of the other is described, the lower layer containing acicular magnetic pigments having a field strength of 5-40 kA/m and a magnetization of 20-70 nTm3/g and the upper layer containing a high-density metal powder dispersion. After application of the layers, the magnetic recording medium is subjected to a magnetic disorientation treatment while the layers are in the wet state, so that said recording medium has virtually no magnetic and mechanical anisotropy. The magnetic recording medium produced in this manner is particularly suitable for floppy disks having a high storage capacity of substantially more than 100 megabytes.
    Type: Grant
    Filed: September 21, 1998
    Date of Patent: May 22, 2001
    Assignee: EMTEC Magnetics GmbH
    Inventors: Hans-Bertram Wiegemann, Peter Stehle, Hansjörg Traub, Helmut Jakusch
  • Patent number: 6232776
    Abstract: A magnetic field sensor that isotropically senses an incident magnetic field. This is preferably accomplished by providing a magnetic field sensor device that has one or more circular shaped magnetoresistive sensor elements for sensing the incident magnetic field. The magnetoresistive material used is preferably isotropic, and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is eliminated. Thus, the resulting magnetic field sensor device provides an output that is relatively independent of the direction of the incident magnetic field in the sensor plane.
    Type: Grant
    Filed: December 18, 1997
    Date of Patent: May 15, 2001
    Assignee: Honeywell Inc.
    Inventors: Bharat B. Pant, Hong Wan
  • Patent number: 6231968
    Abstract: The present invention provides a soft magnetic thin film having high reliability that is useful in a magnetic device such as a magnetic head, where the degradation of heat stability due to a high saturation magnetic flux density of the soft magnetic thin film, the degradation of resistance against surroundings and substrate breakage are suppressed. The magnetic thin film of the present invention comprises a magnetic film comprising approximately columnar, needle or branched magnetic crystal grains as a mother phase, which is formed by sputtering or the like. The magnetic crystal grains have an average maximum length more than 50 nm, and an average crystal size in a short direction of the approximately columnar or needle shape is more than 5 nm and less than 60 nm.
    Type: Grant
    Filed: May 22, 1998
    Date of Patent: May 15, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Hiroshi Sakakima
  • Patent number: 6231963
    Abstract: Described are tape-type magnetic recording media (I) including a non-magnetic substrate (III), at least one film applied to the substrate and, in at least one of these films, an inorganic acicular pigment (II) suitable for use as a supporting pigment, the ratio of the mean length to the mean diameter of the pigment (II) being at least 3 and the mean modulus of elasticity of the films being not less than 15 GPa in the longitudinal direction of the tape-type recording medium (I).
    Type: Grant
    Filed: March 17, 1998
    Date of Patent: May 15, 2001
    Assignee: EMTEC Magnetics GmbH
    Inventors: August Lehner, Helmut Jakusch, Volker Koch, Manfred Ohlinger, Albert Kohl, Werner Lenz, Norbert Schneider, Peter Heilmann, Werner Hübner, Erich Hoffmann, Ronald John Veitch, Rudi Lehnert, Harald Jachow
  • Patent number: 6228482
    Abstract: A magneto-optic recording medium having a reduced demagnetizing field threshold incorporates a thin recording layer having a thickness of less than or equal to approximately 15 nm, and preferably less than or equal to approximately 12 nm. The recording medium thereby exhibits a demagnetizing field threshold of less than or equal to approximately 150 Oe, and preferably less than or equal to approximately 120 Oe. Dielectric and reflective layers in the recording medium stack are tuned to achieve acceptable optical and magnetic characteristics for write and readout operations. The reduced demagnetizing field facilitates use of the recording medium in recording applications that use small magnetic fields for recording and erase. The recording medium is particularly useful in near-field, air-incident recording applications employing magnetic field modulation recording techniques.
    Type: Grant
    Filed: January 6, 1998
    Date of Patent: May 8, 2001
    Assignee: Imation Corp.
    Inventors: Frank E. Aspen, Mark L. Schroeder
  • Patent number: 6228461
    Abstract: A magnetic recording tape favorably employable for recording computer data is composed of a support, and on one side of the support, a non-magnetic layer composed of a non-magnetic powder and a binder, and a magnetic recording layer composed of a ferromagnetic powder and a binder superposed in order, and on the other side, a back-coating layer containing carbon black, in which the magnetic recording tape has a lateral thermal expansion coefficient of not more than 0.0015%/° C., a lateral humidity expansion coefficient of not more than 0.0015%/% RH, a longitudinal offset proof stress of not less than 10 N, and a longitudinal breaking strength of not less than 30 N.
    Type: Grant
    Filed: March 1, 1999
    Date of Patent: May 8, 2001
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Minoru Sueki, Masatoshi Takahashi, Yutaka Kakuishi
  • Patent number: 6224967
    Abstract: The present invention provides a magnetic recording medium having high electromagnetic transfer characteristics and good running durability, whereby a polyester polyol comprising an aliphatic dibasic acid and an aliphatic diol component having no cyclic structure is used as a binder, and a polyurethane is contained, which comprises a polyester polyol having an aliphatic diol where 70 mol % or more of the aliphatic diol has alkyl branched side chain having 2 or more carbon atoms, and said polyurethane has urethane group concentration of 3.0 to 4.0 mmol/g, and said ferromagnetic powder has iron with yttrium at a yttrium/iron ratio of 0.5 to 20 atomic % as a major component.
    Type: Grant
    Filed: May 21, 1998
    Date of Patent: May 1, 2001
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Yuichiro Murayama, Katsuhiko Meguro, Hiroshi Hashimoto