Patents by Inventor Hisashi Takano
Hisashi Takano 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).
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Patent number: 7502189Abstract: To effectively suppress a signal in a low frequency region in which the medium noise and the signal distortion are concentrated, and in order to effectively utilize a detected component of the reproduced signal in the low frequency region, a target of partial response equalization to the perpendicularly recorded/reproduced signal is set so that the low-frequency component around the direct current is suppressed to a regulated quantity for both the effective suppression and the effective utilization. Accordingly, a maximum-likelihood decoding process is carried out through the target of partial response equalization. Reliability of data detection is made higher and a signal-to-noise ratio is improved, so that the noise from the recording medium can be reduced more and it is possible to provide a high-density magnetic recording/reproducing apparatus.Type: GrantFiled: August 29, 2001Date of Patent: March 10, 2009Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Hideki Sawaguchi, Yasutaka Nishida, Hisashi Takano, Hiroyuki Tsuchinaga
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Publication number: 20090021854Abstract: In a method of servo writing of a magnetic recording system and the magnetic recording system, the signal is recorded in a dummy area with a higher recording density than the burst signal. Also, the maximum bit length of the burst area is shortened as compared with the maximum bit length of the data area. A servo control method for perpendicular recording similar to that for longitudinal recording can be used to reduce the development cost. The anti-signal decay performance is also improved. Further, since the variations of the burst signal along the track width is suppressed, the positioning accuracy is improved. These effects combine to produce a reliable magnetic recording system of large capacity.Type: ApplicationFiled: September 9, 2008Publication date: January 22, 2009Inventors: Yasutaka Nishida, Takehiko Hamaguchi, Hideki Sawaguchi, Hisashi Takano
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Publication number: 20090021852Abstract: To effectively suppress a signal in a low frequency region in which the medium noise and the signal distortion are concentrated, and in order to effectively utilize a detected component of the reproduced signal in the low frequency region, a target of partial response equalization to the perpendicularly recorded/reproduced signal is set so that the low-frequency component around the direct current is suppressed to a regulated quantity for both the effective suppression and the effective utilization. Accordingly, a maximum-likelihood decoding process is carried out through the target of partial response equalization. Reliability of data detection is made higher and a signal-to-noise ratio is improved, so that the noise from the recording medium can be reduced more and it is possible to provide a high-density magnetic recording/reproducing apparatus.Type: ApplicationFiled: September 17, 2008Publication date: January 22, 2009Inventors: Hideki Sawaguchi, Yasutaka Nishida, Hisashi Takano, Hiroyuki Tsuchinaga
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Patent number: 7443625Abstract: In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.Type: GrantFiled: April 17, 2006Date of Patent: October 28, 2008Assignee: Hitachi Global Storage Technologies Japan Ltd.Inventors: Takehiko Hamaguchi, Atsushi Nakamura, Yasutaka Nishida, Hisashi Takano, Yohji Maruyama, Hiroshi Ide, Hideki Sawaguchi, Futoshi Tomiyama
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Patent number: 7436611Abstract: In a method of servo writing of a magnetic recording system and the magnetic recording system, the signal is recorded in a dummy area with a higher recording density than the burst signal. Also, the maximum bit length of the burst area is shortened as compared with the maximum bit length of the data area. A servo control method for perpendicular recording similar to that for longitudinal recording can be used to reduce the development cost. The anti-signal decay performance is also improved. Further, since the variations of the burst signal along the track width is suppressed, the positioning accuracy is improved. These effects combine to produce a reliable magnetic recording system of large capacity.Type: GrantFiled: March 17, 2006Date of Patent: October 14, 2008Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Yasutaka Nishida, Takehiko Hamaguchi, Hideki Sawaguchi, Hisashi Takano
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Patent number: 7292417Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.Type: GrantFiled: October 5, 2006Date of Patent: November 6, 2007Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Ryoichi Nakatani, Masahiro Kitada, Hisashi Takano, Hideo Tanabe, Noboru Shimizu
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Patent number: 7259929Abstract: A magnetic recording/reproducing apparatus includes a partial-response equalization circuit having frequency characteristic of cutting off low-frequency signal components inclusive of DC components; and a maximum-likelihood decoder, in which a reproduced signal outputted from the reproducing head is processed by the partial-response equalization circuit and then inputted into the maximum-likelihood decoder to be data-reproduced, thereby reducing a noise and distortion on the reproduced signal and reducing a data detection error rate.Type: GrantFiled: June 24, 2005Date of Patent: August 21, 2007Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Hideki Sawaguchi, Yasutaka Nishida, Hisashi Takano, Toru Matsushita
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Patent number: 7184236Abstract: A hard disk drive and magnetic medium including a servo area, a data area divided into a plurality of sector blocks and at least one micro-servo area disposed between two sector blocks. There may be a micro-servo area immediately preceding each of the plurality of sector blocks. The micro-servo areas include an address mark and a track parity check code that allow the detection of an external shock that causes the recording (write) head to skip to an adjacent track in the hard disk medium. The micro-servo area is smaller than the servo areas, and various numbers of different track parity check codes can be used for different resolution of shock detection. An acceleration sensor may also be provided to detect larger external shocks. By detecting various external shocks with improved accuracy, and aborting the recording operation of data if an external shock is detected, the corruption of data in adjacent tracks is substantially reduced to improve disk drive performance.Type: GrantFiled: September 21, 2004Date of Patent: February 27, 2007Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Takehiko Hamaguchi, Kyo Akagi, Hisashi Takano, Takayuki Ichihara
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Publication number: 20070030604Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.Type: ApplicationFiled: October 5, 2006Publication date: February 8, 2007Inventors: Ryoichi Nakatani, Masahiro Kitada, Hisashi Takano, Hideo Tanabe, Noboru Shimizu
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Patent number: 7159303Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.Type: GrantFiled: March 9, 2006Date of Patent: January 9, 2007Assignee: Hitachi Global Storage Technologies, Ltd.Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
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Patent number: 7133252Abstract: A magnetic head for perpendicular recording without writing from the lateral sides of a main pole and without erasing data on adjacent tracks. A magnetic disk storage apparatus using the magnetic head. The lateral side of the main pole of a magnetic head for perpendicular recording may have an inverted tapered shape obtained by forming a groove as a track portion to an inorganic insulating layer and then forming a magnetic layer and then flattening the upper surface. A leading edge, a trailing edge, or both lateral edges of the magnetic head may be tapered. The taper may be either smooth and linear or curved in profile.Type: GrantFiled: October 25, 2005Date of Patent: November 7, 2006Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Hisashi Takano, Yasutaka Nishida, Tomohiro Okada, Masafumi Michizuki
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Publication number: 20060187578Abstract: For the purpose of letting through a magnetic flux which reverses the magnetization of the magnetic layer of the magnetic disk, a write element requires a predetermined sectional area. However, if a cross section of a magnetic pole is structured as the one having a large aspect ratio, the pole becomes less capable of letting the magnetic flux through effectively. This phenomenon brings about a lower limit on the track width of the magnetic poles and the track density cannot be raised. In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.Type: ApplicationFiled: April 17, 2006Publication date: August 24, 2006Inventors: Takehiko Hamaguchi, Atsushi Nakamura, Yasutaka Nishida, Hisashi Takano, Yohji Maruyama, Hiroshi Ide, Hideki Sawaguchi, Futoshi Tomiyama
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Patent number: 7088548Abstract: To make a soft magnetic underlayer of a double layered perpendicular magnetic recording medium thinner than heretofore while avoiding saturation. Assuming that Tb1 is the thickness of the soft magnetic underlayer of the double layered perpendicular magnetic recording medium, BS2 the saturation flux density of the same, Tm the thickness of a magnetic recording head's main pole 1 along a track direction in the vicinity of its floating surface, TWW the track width of the same, and BS1 the saturation flux density of the same, then Tb1<(BS1×Tm×TWW)/2(BS2×(Tm+TWW)) is satisfied.Type: GrantFiled: October 3, 2003Date of Patent: August 8, 2006Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Yasutaka Nishida, Hisashi Takano, Masafumi Mochizuki
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Publication number: 20060171052Abstract: In a method of servo writing of a magnetic recording system and the magnetic recording system, the signal is recorded in a dummy area with a higher recording density than the burst signal. Also, the maximum bit length of the burst area is shortened as compared with the maximum bit length of the data area. A servo control method for perpendicular recording similar to that for longitudinal recording can be used to reduce the development cost. The anti-signal decay performance is also improved. Further, since the variations of the burst signal along the track width is suppressed, the positioning accuracy is improved. These effects combine to produce a reliable magnetic recording system of large capacity.Type: ApplicationFiled: March 17, 2006Publication date: August 3, 2006Inventors: Yasutaka Nishida, Takehiko Hamaguchi, Hideki Sawaguchi, Hisashi Takano
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Publication number: 20060152862Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.Type: ApplicationFiled: March 9, 2006Publication date: July 13, 2006Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
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Patent number: 7075743Abstract: In a method of servo writing of a magnetic recording system and the magnetic recording system, the signal is recorded in a dummy area with a higher recording density than the burst signal. Also, the maximum bit length of the burst area is shortened as compared with the maximum bit length of the data area. A servo control method for perpendicular recording similar to that for longitudinal recording can be used to reduce the development cost. The anti-signal decay performance is also improved. Further, since the variations of the burst signal along the track width is suppressed, the positioning accuracy is improved. These effects combine to produce a reliable magnetic recording system of large capacity.Type: GrantFiled: August 9, 2001Date of Patent: July 11, 2006Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Yasutaka Nishida, Takehiko Hamaguchi, Hideki Sawaguchi, Hisashi Takano
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Patent number: 7057838Abstract: In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.Type: GrantFiled: April 7, 2003Date of Patent: June 6, 2006Assignee: Hitachi, Ltd.Inventors: Takehiko Hamaguchi, Atsushi Nakamura, Yasutaka Nishida, Hisashi Takano, Yohji Maruyama, Hiroshi Ide, Hideki Sawaguchi, Futoshi Tomiyama
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Patent number: 7054120Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.Type: GrantFiled: November 5, 2003Date of Patent: May 30, 2006Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
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Publication number: 20060103978Abstract: A magnetic head for perpendicular recording without writing from the lateral sides of a main pole and without erasing data on adjacent tracks. A magnetic disk storage apparatus using the magnetic head. The lateral side of the main pole of a magnetic head for perpendicular recording may have an inverted tapered shape obtained by forming a groove as a track portion to an inorganic insulating layer and then forming a magnetic layer and then flattening the upper surface. A leading edge, a trailing edge, or both lateral edges of the magnetic head may be tapered. The taper may be either smooth and linear or curved in profile.Type: ApplicationFiled: October 25, 2005Publication date: May 18, 2006Inventors: Hisashi Takano, Yasutaka Nishida, Tomohiro Okada, Masafumi Mochizuki
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Patent number: 7016156Abstract: Magnetic disk apparatus includes an electric wiring capable of satisfying an electric condition under which high frequency recording higher than or equal to 200 MHz, a magnetic head having at least a recording device to a magnetic recording medium, and also the electric wiring corresponding to a recording current supplying device to this magnetic head are formed on a suspension member for mechanically suspending the magnetic head, the recording current being supplied to a magnetic head recording device by employing such electric wiring, the characteristic impedance of which is higher than a maximum impedance of the magnetic head recording device.Type: GrantFiled: October 12, 2004Date of Patent: March 21, 2006Assignee: Hitachi, Ltd.Inventors: Yohji Maruyama, Hiroshi Ikekame, Hisashi Takano