Patents by Inventor Junji Hirokane

Junji Hirokane 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: 20020168549
    Abstract: A magneto-optical recording medium includes at least a first magnetic layer, a second magnetic layer and a third magnetic layer which are layered in this order, the first magnetic layer being formed of a perpendicularly magnetized film having a relatively small wall coercivity and a relatively large wall mobility compared with the third magnetic layer in the vicinity of a predetermined temperature, and the magneto-optical recording medium satisfies conditions
    Type: Application
    Filed: November 21, 2001
    Publication date: November 14, 2002
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Noboru Iwata, Junji Hirokane
  • Publication number: 20020159339
    Abstract: A magneto-optical recording medium is provided with at least: a recording layer, made of a perpendicular magnetization film, in which magnetized information is recorded in the form of a perpendicular direction of magnetization; a magnetic flux generating layer, made of a perpendicular magnetization film, which is exchange-coupled with the recording layer; and a read-out layer, having a perpendicular magnetization at a predetermined temperature or higher temperatures than the predetermined temperature, which copies the magnetized information of the recording layer by magneto-static coupling with the magnetic flux generating layer and the recording layer, wherein the magnetic flux generating layer is a magnetic film having a lower Curie temperature than that of the recording layer and having a larger total magnetization than that of the recording layer at a temperature at which the read-out layer has a perpendicular magnetization.
    Type: Application
    Filed: April 25, 2002
    Publication date: October 31, 2002
    Inventors: Junji Hirokane, Noboru Iwata
  • Patent number: 6463015
    Abstract: A magneto-optical recording medium of the present invention has a recording layer made of a perpendicular magnetization film, and a readout layer which is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature. When the magneto-optical recording medium is irradiated with a light beam, the readout layer separates into three regions: a region in an in-plane magnetization state, a region in a perpendicular magnetization state, and a region having a temperature not lower than the Curie temperature thereof. Only the region in the perpendicular magnetization state allows copying of the magnetization of the recording layer. Therefore, even when the diameter and intervals of recording bits on the recording layer are very small, it is possible to reproduce a target recording bit separately from a recording bit adjacent to the target recording bit.
    Type: Grant
    Filed: August 8, 2000
    Date of Patent: October 8, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Yoshiteru Murakami, Akira Takahashi
  • Patent number: 6463016
    Abstract: A magneto-optical recording medium according to the present invention includes a reproducing layer having in-plane magnetization at room temperature and shifting to have perpendicular magnetization at temperatures at and above a critical temperature, a first in-plane magnetized layer having a Curie temperature in the vicinity of the critical temperature, a second in-plane magnetized layer having a Curie temperature higher than that of the first in-plane magnetized layer, and a recording layer made of a perpendicularly magnetized film, provided in that order.
    Type: Grant
    Filed: January 28, 2000
    Date of Patent: October 8, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata
  • Patent number: 6456571
    Abstract: A magneto-optical recording medium comprising a recording magnetic layer made of a perpendicularly magnetized film and a multilayer reproducing film, wherein the multilayer reproducing film has two reproducing magnetic layers which are in a in-plane magnetized state at room temperature and shift to a perpendicularly magnetized state with a rise in temperature and an in-panel magnetized layer disposed between the two reproducing magnetic layers, which is in an in-plane magnetized state from room temperature to a Curie temperature and has a lower Curie temperature than the recording magnetic layer and the reproducing magnetic layers.
    Type: Grant
    Filed: March 31, 2000
    Date of Patent: September 24, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata
  • Publication number: 20020115023
    Abstract: A method for forming micropatterns includes forming a thin film consisting of a single layer or of plural layers on a substrate, irradiating an energy beam to the thin film to elevate the temperature of a region to a predetermined temperature or higher to thereby modify the region of the thin film, and patterning the thin film at least in such a manner to leave over the modified region.
    Type: Application
    Filed: February 15, 2002
    Publication date: August 22, 2002
    Inventors: Junji Hirokane, Michinobu Mieda, Go Mori
  • Patent number: 6430115
    Abstract: A reproducing layer having perpendicular magnetization in a single layer, an in-plane magnetic layer, and a recording layer having perpendicular magnetization are formed in this order. When the reproducing layer, the in-plane magnetic layer, and the recording layer have the Curie temperatures of Tc1, Tc2, and Tc3, these values satisfy conditions of Tc2<Tc1 and Tc2<Tc3. The reproducing layer has in-plane magnetization due to an exchange coupling with the in-plane magnetic layer at lower than Tc2. At Tc2 or higher, magnetization information is expanded and transferred from the recording layer to the reproducing layer, so that the reproducing layer has single-domain perpendicular magnetization.
    Type: Grant
    Filed: August 31, 1999
    Date of Patent: August 6, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata
  • Patent number: 6418091
    Abstract: There are provided a magneto-optical disk, a super-resolution magneto-optical disk and a domain wall moving magneto-optical disk whose cross-talk, cross-write and cross-erasure are suppressed and whose recording density is improved. A recording magnetic layer formed on a land is shut off magnetically from the recording magnetic layer formed on a groove and thermal diffusion in the track direction is suppressed, by selectively oxidizing a magnetic layer formed on a side wall between the land and the groove.
    Type: Grant
    Filed: December 15, 1999
    Date of Patent: July 9, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata
  • Publication number: 20020080689
    Abstract: A recording and reproducing device of the present invention is provided to achieve the object of realizing stable and desirable recording and reproducing of information by suppressing fluttering of an optical disk by way of suppressing pressure fluctuation which is caused, for example, when an objective lens or an optical pickup with the objective lens is moved. The object is attained by a transparent stabilizer, provided between a disk and an optical pickup, which is moved with the optical pickup, and a slider which is provided to face the transparent stabilizer with the disk in between. The slider is supported to oscillate, and the surface of the slider facing the disk is flat. During rotation of the disk, the slider moves to balance the air pressure between the transparent stabilizer and the disk with that between the slider and the disk.
    Type: Application
    Filed: December 27, 2001
    Publication date: June 27, 2002
    Inventors: Junji Hirokane, Noboru Iwata
  • Publication number: 20020034154
    Abstract: A disc-like recording medium provided with a disc substrate having a hole at its center and a circular information recording area at its surface that is concentric with the hole, and a hub that is fitted to the hole, wherein the disc substrate has a relief portion thereon for position alignment of the hub.
    Type: Application
    Filed: August 3, 2001
    Publication date: March 21, 2002
    Inventors: Noboru Iwata, Junji Hirokane
  • Patent number: 6352765
    Abstract: A magneto-optical recording medium includes at least a first magnetic layer, a second magnetic layer and a third magnetic layer which are layered in this order, the first magnetic layer being formed of a perpendicularly magnetized film having a relatively small wall coercivity and a relatively large wall mobility compared with the third magnetic layer in the vicinity of a predetermined temperature, and the magneto-optical recording medium satisfies conditions Tc2<Tcomp1<Tc1 and Tc2<Tcomp1<Tc3 where Tcomp1 is a compensation temperature of the first magnetic layer, Tc1, Tc2 and Tc3 are Curie temperatures of the first, second and third magnetic layers, respectively.
    Type: Grant
    Filed: December 10, 1999
    Date of Patent: March 5, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Noboru Iwata, Junji Hirokane
  • Patent number: 6346322
    Abstract: A magneto-optical recording medium includes at least a first magnetic layer, a second magnetic layer, a third magnetic layer, a non-magnetic intermediate layer and a fourth magnetic layer which are layered in this order, the first magnetic layer being formed of a perpendicularly magnetized film having a relatively small wall coercivity and a relatively large wall mobility compared with the third magnetic layer in the vicinity of a predetermined temperature, the second magnetic layer being formed of a magnetic film whose Curie temperature is lower than the Curie temperatures of the first magnetic layer and third magnetic layer, the fourth magnetic layer being a perpendicularly magnetized film with a uniform magnetization direction and forming a region having a uniform magnetization direction in the first magnetic layer by magnetostatic coupling with the first magnetic layer when the second magnetic layer is heated to a predetermined temperature or a higher temperature.
    Type: Grant
    Filed: December 7, 1999
    Date of Patent: February 12, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Noboru Iwata, Junji Hirokane
  • Patent number: 6295271
    Abstract: An optical disk has address recording sections each of which has a wobbled part of one of side walls of a groove. Each address recording section is formed by providing convexes of a groove in an adjacent land so as to widen the groove. With the wobbles thus provided in a concavo-convex form, address information is recorded. Besides, the address recording sections thus provided in the grooves are linearly disposed in radial directions of the optical disk. By thus arranging the optical disk on whose grooves and/or lands information is recorded, mixing of wobble frequency components in reproduced information signals does not occur, the sector method is applicable to the optical disk, and information signals of high quality can be obtained.
    Type: Grant
    Filed: December 30, 1999
    Date of Patent: September 25, 2001
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Tetsuya Inui, Hideaki Sato, Junichiro Nakayama, Naoyasu Iketani, Michinobu Mieda, Yoshiteru Murakami, Junji Hirokane, Akira Takahashi
  • Patent number: 6278668
    Abstract: A magneto-optical storage medium includes: a reproduction layer exhibiting an in-plane magnetization state at room temperature and changing to a perpendicular magnetization state at a transition temperature Tp1; a supplementary reproduction layer exhibiting an in-plane magnetization state at room temperature and changing to a perpendicular magnetization state at a transition temperature Tp2; a non-magnetic intermediate layer; and a storage layer made of a perpendicular magnetization film, the layers being deposited in this order, the magneto-optical storage medium being arranged so as to satisfy: Tp1<Tp2 This arrangement enables the magneto-optical storage medium to amplify the magnetic information stored in the storage layer and duplicate it to the reproduction layer, and signals whose cycle is equal to, or below, diffraction limits of light to be reproduced from the storage layer without reducing the amplitude.
    Type: Grant
    Filed: November 18, 1999
    Date of Patent: August 21, 2001
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata, Akira Takahashi
  • Patent number: 6272077
    Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.
    Type: Grant
    Filed: January 7, 2000
    Date of Patent: August 7, 2001
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Takahashi, Michinobu Mieda, Naoyasu Iketani, Go Mori, Junsaku Nakajima, Yoshiteru Murakami, Junji Hirokane
  • Publication number: 20010009709
    Abstract: In the present invention, in a pre-recorded information recording region on an optical disk capable of recording in both a land and a groove, a first address region is displaced off a second address region along the length of the track. Address information is stored by a first pit string P1 following a groove G1 in the first address region and by a second pit string P2 following a groove G2 in the second address region. The first pit string P1 and the second pit string P2 are adapted so that the gaps between pits constituting those strings in accordance with address information are equal to, or less than, the width of the pits measured in a radial direction of the disk. Thus, the present invention offers an optical disk and a recording/reproducing device which effect a stable tracking control.
    Type: Application
    Filed: January 26, 2001
    Publication date: July 26, 2001
    Inventors: Junji Hirokane, Noboru Iwata
  • 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: 6178143
    Abstract: A magneto-optical recording medium has a recording layer made of a perpendicular magnetization film, and a readout layer which is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature. When the magneto-optical recording medium is irradiated with a light beam, the readout layer separates into three regions: a region in an in-plane magnetization state, a region in a perpendicular magnetization state, and a region having a temperature not lower than the Curie temperature thereof. Only the region in the perpendicular magnetization state allows copying of the magnetization of the recording layer. Therefore, even when the diameter and intervals of recording bits on the recording layer are very small, it is possible to reproduce a target recording bit separately from a recording bit adjacent to the target recording bit.
    Type: Grant
    Filed: February 25, 1999
    Date of Patent: January 23, 2001
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Yoshiteru Murakami, Akira Takahashi
  • Patent number: 6150038
    Abstract: A reproducing layer, an intermediate layer, and a recording layer are successively stacked. The reproducing layer is made of a perpendicularly magnetized film whose domain wall coercivity is relatively smaller and whose domain wall mobility is relatively larger as compared with the recording layer around a reproducing temperature. When the reproducing layer, the intermediate layer, and the recording layer have Curie temperatures of Tc1, Tc2, and Tc3, Tc1, Tc2, and Tc3 satisfy a relationship of Tc2<Tc1<Tc3. Upon reproducing information, the reproducing layer is partially heated to more than the Curie temperature by irradiating with a light beam. This arrangement makes it possible to expand and reproduce a domain without causing a repetition of reproduction and to reproduce a signal having a period which is not more than an optical diffraction limit without reducing an amplitude of the reproduced signal, thereby dramatically improving a recording density.
    Type: Grant
    Filed: April 27, 1999
    Date of Patent: November 21, 2000
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junji Hirokane, Noboru Iwata
  • Patent number: 6147939
    Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.
    Type: Grant
    Filed: March 2, 1998
    Date of Patent: November 14, 2000
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Takahashi, Michinobu Mieda, Naoyasu Iketani, Go Mori, Junsaku Nakajima, Yoshiteru Murakami, Junji Hirokane