Patents by Inventor Katsumichi Tagami

Katsumichi Tagami has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20060221511
    Abstract: A TMR effect element with sufficiently reduced element resistance and restricted popping noise is provided, which comprises a tunnel barrier layer formed primarily of a metal oxide including many electric charge sites. The electric charge sites density n and the mobility ? of electrons trapped due to the electric charge sites satisfy a relationship expressed by: 0<(ns1?1?ns2?1)?1·(?0??)·(n?)?1<0.2, where ns1 and ns2 are densities of tunnel electrons when an element resistance is a minimum and maximum respectively during reading signals and ?0 is the mobility of electrons when not trapped.
    Type: Application
    Filed: March 24, 2006
    Publication date: October 5, 2006
    Applicant: TDK Corporation
    Inventors: Shunji Saruki, Kenji Inage, Tetsuya Kuwashima, Hiroshi Kiyono, Katsumichi Tagami, Kazumasa Fukuda, Masahide Kohno
  • Publication number: 20060221499
    Abstract: The present invention provides a thin film magnetic head realizing the gradient and the strength of a perpendicular magnetic field increased as much as possible. A main magnetic pole layer is made recede from a write shield layer. As compared with the case where the magnetic pole layer is not receded from the write shield layer, an overlap range in which the main magnetic pole layer and the write shield layer are overlapped one another is smaller. Accordingly, the amount of magnetic flux emitted from the main magnetic pole layer toward a recording medium relatively increases, and the amount of magnetic flux leaked from the main magnetic pole layer to the write shield layer relatively decreases.
    Type: Application
    Filed: January 27, 2006
    Publication date: October 5, 2006
    Applicant: TDK CORPORATION
    Inventors: Katsumichi Tagami, Yuji Ito, Masaru Hirose, Toshiaki Maeda, Nobutaka Nishio
  • Patent number: 7095581
    Abstract: A convex structure, where a servo signal is recorded, of a perpendicular magnetic recording medium is set to a truncated quadrangular pyramid shape and a specification of the truncated quadrangular pyramid shape and so forth are determined according to properties of the perpendicular magnetic recording medium to be used, so that the influence of a demagnetizing field that accelerates thermal fluctuation of the perpendicular magnetic recording medium can be reduced in a servo area of the medium which is most affected by the thermal fluctuation of the medium. Therefore, it is possible to provide a magnetic recording and reproducing apparatus having the magnetic recording medium that can suppress degradation of the servo signal caused by the thermal fluctuation of magnetization of perpendicular magnetic recording layers forming a convex-concave structure in the servo area to thereby ensure a stable servo function over the long term.
    Type: Grant
    Filed: April 20, 2005
    Date of Patent: August 22, 2006
    Assignee: TDK Corporation
    Inventor: Katsumichi Tagami
  • Patent number: 7090934
    Abstract: The present invention provides a perpendicular magnetic recording medium 11 having a perpendicular magnetization film 22 formed on a substrate 20, wherein a high perpendicular orientation film 24 having higher perpendicular orientation than that of the perpendicular magnetization film 22 is formed over or/and under the perpendicular magnetization film 22.
    Type: Grant
    Filed: May 8, 2002
    Date of Patent: August 15, 2006
    Assignee: Hoya Corporation
    Inventors: Hirotaka Hokkyo, Shinzo Tsuboi, Katsumichi Tagami
  • Publication number: 20060132970
    Abstract: A perpendicular magnetic recording/reproducing device that can suppress broadening of recording magnetic fields and that is capable of effective application of magnetic field to a recording target track is provided. The device includes a magnetic recording medium having a soft magnetic layer and a recording layer having a perpendicular magnetic anisotropy formed in this order over a substrate, and a magnetic head. The soft magnetic layer is formed with a concavo-convex pattern in which at least part of regions corresponding to tracks of the recording layer protrudes toward the recording layer, and convex portions are provided with the magnetic anisotropy in the circumferential direction of the tracks. The magnetic head includes a main pole for generating a recording magnetic field, and a return pole to which the magnetic field returns, the main pole and the return pole being arranged side by side in a track width direction.
    Type: Application
    Filed: December 9, 2005
    Publication date: June 22, 2006
    Applicant: TDK CORPORATION
    Inventors: Mitsuru Takai, Katsumichi Tagami, Kazuya Shimakawa
  • Publication number: 20060132972
    Abstract: A thin-film magnetic head with which an error rate is decreased due to a reduction of a jitter without significant decrease in write field, is provided. The head comprises at least one inductive write head element comprising: a main magnetic pole layer having an inner saturation magnetic flux density varying from both side end surfaces in a track-width direction and a leading end surface, toward a center portion in the track-width direction of a trailing end surface; an auxiliary magnetic pole layer; and at least one coil layer, a curvature width WC of a contour line of a write field adjacent to a trailing edge on an ABS side of the main magnetic pole layer satisfying the following expression: ?0.15*WT=WC<12 where WT is a track width and a unit of WC and WT is nanometer.
    Type: Application
    Filed: December 15, 2005
    Publication date: June 22, 2006
    Applicants: TDK Corporation, SAE Magnetics (H.K) Ltd., SAE Technology Centre.
    Inventors: Katsumichi Tagami, Tatsuya Harada, Hiroki Matsukuma, Tetsuya Roppongi, Susumu Aoki, Kazumasa Fukuda, Naoto Matono
  • Publication number: 20060077880
    Abstract: An information recording medium excellent in surface smoothness. The information recording medium has a data track pattern and a servo pattern formed on at least one surface of a substrate by a concave/convex pattern including a plurality of convex portions. The concave/convex pattern has concave portions each having a non-magnetic material embedded therein. An A concave/convex pattern forming the servo pattern includes a plurality of servo convex portions formed in a manner associated with servo data. At least part of the plurality of servo convex portions are formed by a B concave/convex pattern including a plurality of non-servo convex portions. This arrangement makes it possible to maintain excellent surface smoothness within a servo pattern area, thereby enabling the recording/reproducing apparatus to execute stable recording and reproducing on and from the information recording medium.
    Type: Application
    Filed: September 14, 2005
    Publication date: April 13, 2006
    Applicant: TDK Corporation
    Inventors: Makoto Moriya, Katsumichi Tagami
  • Publication number: 20060066984
    Abstract: A magnetic recording and reproducing apparatus includes a magnetic head having a main magnetic pole, a magnetic recording medium of a discrete type having a predetermined convex-concave structure at data tracks and servo tracks, and a drive device body that can operate to rotationally drive the magnetic recording medium in a constant direction and cause the magnetic head to be movable in substantially radial directions of the magnetic recording medium. A relationship among parameters specifying a predetermined convex-concave shape of the data track, parameters specifying the main magnetic pole, and a skew angle is defined by a predetermined inequality. By setting a specification of the magnetic recording and reproducing apparatus in the range defined by the inequality, it is possible to prevent unwanted writing into the adjacent track to thereby realize high-density recording having extremely high reliability.
    Type: Application
    Filed: May 25, 2005
    Publication date: March 30, 2006
    Applicant: TDK Corporation
    Inventor: Katsumichi Tagami
  • Publication number: 20060044670
    Abstract: Servo regions are re-magnetized in the present invention. A magnetic storage device measures a first amount which is indicative of the magnitude of magnetization of a servo region, by a read head portion. The first amount may be a reproduced output, or an inverse of a gain used in an automatic gain control, etc. Servo regions are re-magnetized by a write head portion, when a servo region is detected in which a ratio of the measured first amount to an initial value of the first amount is smaller than a predetermined value, i.e., it is determined that the magnetization is reduced.
    Type: Application
    Filed: May 24, 2005
    Publication date: March 2, 2006
    Applicant: TDK Corporation
    Inventor: Katsumichi Tagami
  • Publication number: 20060040140
    Abstract: A perpendicular recording type, magnetic recording medium having a soft magnetic layer and a magnetic recording/reproducing apparatus including such a magnetic recording medium are provided. The magnetic recording medium allows the recording magnetic field to be efficiently applied to a track for recording while restricting the extent of the recording magnetic field. The magnetic recording medium has a soft magnetic layer and a recording layer formed in this order on a substrate. The soft magnetic layer has its part on the opposite side to the substrate formed in a concavo-convex pattern. The recording layer is oriented to have magnetic anisotropy in the direction perpendicular to the surface. A fixing layer for fixing the magnetic anisotropy of the soft magnetic layer in a predetermined direction parallel to the surface is provided between the recording layer and the soft magnetic layer.
    Type: Application
    Filed: August 10, 2005
    Publication date: February 23, 2006
    Applicant: TDK CORPORATION
    Inventors: Akimasa Kaizu, Katsumichi Tagami, Kazuya Shimakawa
  • Publication number: 20060023329
    Abstract: In the present invention, with respect to a convex-concave structure necessary for respective functions of a servo area in a perpendicular magnetic recording medium, a specification of configuration and magnetic property of a convex-concave magnetic layer of the perpendicular magnetic recording medium is set so as to overcome a demagnetizing field that accelerates thermal fluctuation. Therefore, in a magnetic recording and reproducing apparatus using the perpendicular magnetic recording medium having servo tracking signals at convex portions of the magnetic layer formed in a convex-concave pattern, it is possible to suppress degradation of the servo signals caused by the thermal fluctuation to thereby ensure a stable servo function over the long term.
    Type: Application
    Filed: April 25, 2005
    Publication date: February 2, 2006
    Applicant: TDK Corporation
    Inventor: Katsumichi Tagami
  • Publication number: 20060007573
    Abstract: A convex structure, where a servo signal is recorded, of a perpendicular magnetic recording medium is set to a truncated quadrangular pyramid shape and a specification of the truncated quadrangular pyramid shape and so forth are determined according to properties of the perpendicular magnetic recording medium to be used, so that the influence of a demagnetizing field that accelerates thermal fluctuation of the perpendicular magnetic recording medium can be reduced in a servo area of the medium which is most affected by the thermal fluctuation of the medium. Therefore, it is possible to provide a magnetic recording and reproducing apparatus having the magnetic recording medium that can suppress degradation of the servo signal caused by the thermal fluctuation of magnetization of perpendicular magnetic recording layers forming a convex-concave structure in the servo area to thereby ensure a stable servo function over the long term.
    Type: Application
    Filed: April 20, 2005
    Publication date: January 12, 2006
    Applicant: TDK Corporation
    Inventor: Katsumichi Tagami
  • Publication number: 20060007594
    Abstract: The present invention relates to a thin-film magnetic head with a heater. A thin-film magnetic head includes a substrate, a magnetic read head element that has a shield area and is formed on the substrate, a magnetic write head element that has a pole area and is formed on the opposite side of the substrate with respect to the magnetic read head element, an overcoat layer that covers the magnetic read head element and the magnetic write head element and is formed on the substrate, a heater that heats at least during the magnetic read head element or the magnetic write head element in operation and is formed in the overcoat layer, and a slit area that splits the shield area in a shield length direction and is made of lower thermal conductivity material than the one of the shield area.
    Type: Application
    Filed: May 13, 2005
    Publication date: January 12, 2006
    Applicant: TDK Corporation
    Inventors: Tsuyoshi Umehara, Norikazu Ota, Katsumichi Tagami, Hiroki Matsukuma, Nobuya Oyama, Soji Koide, Yoshiyuki Mizoguchi, Kazuhide Yamada
  • Publication number: 20050286155
    Abstract: The burst pattern shape in a discrete medium is set to a shape (truncated quadrangular pyramid shape) having substantially trapezoidal shapes in a track width direction and in a track circumferential direction, respectively, and a predetermined relationship is satisfied among W1, W2, Tp, and Wr where W1 represents an upper side corresponding to the surface of a convex magnetic recording layer and W2 a lower side corresponding to the lower surface of the convex magnetic recording layer in the trapezoidal shape in the track width direction, Tp represents a data track pitch of a data information recording portion, and Wr represents a read width of a magnetic head. Therefore, the burst pattern shape makes it possible to largely reduce a production load in processing and still to obtain an accurate position error signal.
    Type: Application
    Filed: April 22, 2005
    Publication date: December 29, 2005
    Applicant: TDK Corporation
    Inventors: Katsumichi Tagami, Yoshikazu Soeno, Kazuya Shimakawa, Hiroki Matsukuma
  • Publication number: 20050287397
    Abstract: A magnetic recording medium is provided which has good recording/reproducing characteristics with a recording layer divided in a number of recording elements by a predetermined concavo-convex pattern, and a manufacturing method that enables efficient manufacture of such a magnetic recording medium. The magnetic recording medium includes a substrate, a soft magnetic layer formed over the substrate, a recording layer formed over the soft magnetic layer such as to have magnetic anisotropy in a direction perpendicular to surface, and being divided in a number of recording elements by a predetermined concavo-convex pattern, and a non-magnetic intermediate layer formed between the recording layer and the soft magnetic layer. The recording elements are formed to have a predetermined track shape in a data region.
    Type: Application
    Filed: May 24, 2005
    Publication date: December 29, 2005
    Applicant: TDK CORPORATION
    Inventors: Yoshikazu Soeno, Mitsuru Takai, Katsumichi Tagami, Kazuya Shimakawa
  • Publication number: 20050270694
    Abstract: A thin-film magnetic head according to the present invention comprises: a substrate; at least one magnetic head element formed on the substrate; an overcoat multilayer composed of a plurality of overcoat layers, formed on the substrate so as to cover the at least one magnetic head element; and at least one heating element to be heated at least during operation of the at least one magnetic head element, the at least one heating element provided in the overcoat multilayer, and a coefficient of thermal expansion of an overcoat layer located farthest from the substrate in the overcoat multilayer being smaller than a coefficient of thermal expansion of an overcoat layer located closest to the substrate in the overcoat multilayer.
    Type: Application
    Filed: May 13, 2005
    Publication date: December 8, 2005
    Applicant: TDK Corporation
    Inventors: Tsuyoshi Umehara, Norikazu Ota, Katsumichi Tagami, Hiroki Matsukuma, Nobuya Oyama, Soji Koide, Yoshiyuki Mizoguchi, Kazuhide Yamada
  • Publication number: 20050243467
    Abstract: A magnetic recording medium having high reliability is provided, in which concave portions between recording elements formed as convex portions of a concavo-convex pattern are approximately completely filled with a non-magnetic material. The magnetic recording medium is a plate-like body including: a substrate; a recording layer that is formed in a predetermined concavo-convex pattern over the substrate and includes recording elements for recording information formed as convex portions of the concavo-convex pattern; and the non-magnetic material filling concave portions between the recording elements. Side faces of the recording elements are inclined to face a surface of the plate-like body on a side toward which the recording elements 16 project in the concavo-convex pattern. An inclination angle of the side faces of the recording elements with respect to a direction perpendicular to that surface is smaller than 90° and 5° or more.
    Type: Application
    Filed: April 27, 2005
    Publication date: November 3, 2005
    Applicant: TDK CORPORATION
    Inventors: Mitsuru Takai, Yoshikazu Soeno, Katsumichi Tagami, Kazuya Shimakawa
  • Publication number: 20050233176
    Abstract: In an information recording medium where respective concave parts of a magnetic layer, which is formed on at least one side e of a substrate and in which a predetermined convex/concave pattern has been formed, are filled with non-magnetic material and non-magnetic layers are formed by the non-magnetic material in at least partial regions of respective upper surfaces of respective convex parts of the magnetic layer, the non-magnetic layers are formed so that parts thereof protrude further in a direction in which the convex parts protrude than other parts of the non-magnetic layers.
    Type: Application
    Filed: March 22, 2005
    Publication date: October 20, 2005
    Applicant: TDK Corporation
    Inventors: Mitsuru Takai, Yoshikazu Soeno, Katsumichi Tagami, Kazuya Shimakawa, Takahiro Suwa
  • Publication number: 20020182445
    Abstract: The present invention provides a perpendicular magnetic recording medium 11 having a perpendicular magnetization film 22 formed on a substrate 20, wherein a high perpendicular orientation film 24 having higher perpendicular orientation than that of the perpendicular magnetization film 22 is formed over or/and under the perpendicular magnetization film 22.
    Type: Application
    Filed: May 8, 2002
    Publication date: December 5, 2002
    Inventors: Hirotaka Hokkyo, Shinzo Tsuboi, Katsumichi Tagami
  • Patent number: 6426157
    Abstract: The present invention provides a perpendicular magnetic recording medium 11 having a perpendicular magnetization film 22 formed on a substrate 20, wherein a high perpendicular orientation film 24 having higher perpendicular orientation than that of the perpendicular magnetization film 22 is formed over or/and under the perpendicular magnetization film 22.
    Type: Grant
    Filed: August 3, 1999
    Date of Patent: July 30, 2002
    Assignee: NEC Corporation
    Inventors: Hirotaka Hokkyo, Shinzo Tsuboi, Katsumichi Tagami