Abstract: Embodiments of the present invention reduce lowering of a recording current and a recording magnetic field that might occur upon execution of write pre-compensation for compensating the NLTS according to a perpendicular magnetic recording method. According to one embodiment, the recording current overshoot is increased for recording a high NLTS recording data pattern. The read signal quality is improved, thereby a highly reliable magnetic disk can be provided.

Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium capable of suppressing a magnetic field intensity applied to adjacent tracks on a patterned perpendicular recording medium. According to one embodiment of the present invention, unevenly formed soft under layers are stacked on a flat nonmagnetic substrate, thereby the saturation magnetic flux density of the protruded region is set lower than that of the flat region.

Abstract: 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.

Abstract: There are provided a magnetic head and a magnetic disk apparatus wherein an upper magnetic pole is so shaped that, at a position where skew angle is maximum, the maximum of its projected length in the radial direction of a magnetic disk is not more than the track pitch of the magnetic disk, whereby acceleration of thermal relaxation of information recorded on adjacent tracks is obviated even in an area where the skew angle is large.

Abstract: In a partial-response maximum-likelihood (PRML) signal detection and processing technique, reduction of data detection error events caused due to medium noise is achieved. For a PRML detection data result obtained after PRML data demodulation, a code error event that depends on a signal distance, and which has a high frequency of occurrence, is noticed and its occurrence probability is estimated. A locally-existing medium noise quantity is estimated from preceding and subsequent code patterns of the PRML detection data result. Based on this, the occurrence probability of the error event is compensated to improve the detection precision. As a result, data modulation with reliability higher than conventional maximum likelihood detection can be realized with a simple circuit structure.

Abstract: A sheet attaching instrument (10) that includes an instrument body (11) and an attachment member (12), in which at least one engaging hole (50) is provided with a fall-stop (58) that can hold an attachment projection (30) in an area between an inserting section (51) and a holding section (52), and at least one peripheral edge of a pair of lateral side areas extending from the inserting section (51) to the holding section (52) through the fall-stop (58) is provided with a bridge (54) of which middle section is elastically deformable.

Abstract: Embodiments of the invention provide a magnetic head which can suppress broadening of the magnetic field distribution in the track-width direction without reducing the magnetic field intensity. In one embodiment, a main pole is composed of a pole tip having a part providing a write-track width, and a yoke part recessed from the air bearing surface in the element-height direction, where the trailing side surface of the pole tip is made as an asymmetric structure with respect to the track center.

Abstract: Embodiments of the invention improve efficiency in alternating-current demagnetization of a magnetic recording medium. In specific embodiments, magnet fields in a direction slanting to an easy direction of magnetization of recording layer magnetization of a medium in rotation are applied.

Abstract: 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.

Abstract: A buckle includes a socket (10), a plug (20) of which tip end part can be inserted into and released from the socket by pressing both sides of the socket by a manual operation. The plug has a base (21) located on a base end of the plug, a pair of lock arms (22) extending to the tip end of the plug from the base, an engaging part (24) provided on the intermediary of the lock arm and engageable with the inside of the socket, a pressing part (25) provided on the intermediary of the lock arm and pressed by the manual operation, and a bridge (30) for connecting the intermediaries of the lock arms.

Abstract: 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.

Abstract: A method of enhancing the thermal stability of gray codes is disclosed. The gray code block in a servo area is recorded with a combination of two different magnetization directions. When the two different magnetization directions are expressed as “+” and “?”, the information “1” is recorded as “++??” or “??++” with the information “0” recorded as “+?+?” or “?+?+”. Since the filter for gray code demodulation is provided with a perpendicular recording mode, the servo area does not use long-wavelength signals that are susceptible to thermal demagnetization. As a result, thermal stability is enhanced.

Abstract: 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.

Abstract: A plug (20) has a guide bar (24) to be inserter in a socket (30). The guide bar (24) has a to-be-held section (241) at a tip end thereof, a dent (244) at a middle portion thereof, and a sub to-be-held section (242) at a base end thereof. When making an engagement, the plug (20) is slanted relative to the socket (30), so that the guide bar (24) contacts contact points (P1, P2). When the plug has been inserted into a depth end of the socket, the to-be-held section (241) and the sub to-be-held section (242) are held by a holding section (342) and a sub holding section (343) of the socket (30), thereby stabilizing engagement posture.

Abstract: 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.

Abstract: In a partial-response maximum-likelihood (PRML) signal detection and processing technique, reduction of data detection error events caused due to medium noise is achieved. For a PRML detection data result obtained after PRML data demodulation, a code error event that depends on a signal distance, and which has a high frequency of occurrence, is noticed and its occurrence probability is estimated. A locally-existing medium noise quantity is estimated from preceding and subsequent code patterns of the PRML detection data result. Based on this, the occurrence probability of the error event is compensated to improve the detection precision. As a result, data modulation with reliability higher than conventional maximum likelihood detection can be realized with a simple circuit structure.

Abstract: 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.

Abstract: Embodiments of the invention avoid loss of information as recorded, due to an external magnetic field applied. In one embodiment, a pole expanded part prone to occurrence of magnetic saturation is formed so as to prevent magnetic fluxes from being converged at ends of a return pole of a magnetic head.

Abstract: A method of enhancing the thermal stability of gray codes is disclosed. The gray code block in a servo area is recorded with a combination of two different magnetization directions. When the two different magnetization directions are expressed as “+” and “?”, the information “1” is recorded as “++??” or “??++” with the information “0” recorded as “+?+?” or “?+?+”. Since the filter for gray code demodulation is provided with a perpendicular recording mode, the servo area does not use long-wavelength signals that are susceptible to thermal demagnetization. As a result, thermal stability is enhanced.

Abstract: A magnetic disk apparatus including: a disk holding data as magnetic information on a magnetic recording film; a head to perform writing and reading of the magnetic information; a rotary actuator to move the head in a radial direction of the disk; plural heat elements in the head to locally heat the disk; a write element in the head to apply a magnetic field to the disk; and means for selecting at least one heat element from the plural heat elements, wherein the means for selecting the heat element selects at least one heat element from the plural heat elements so as to bring a center line of an area heated by the heat element and a center line of the position of the magnetic field generated by the write element into approximate correspondence, in correspondence with a relative angle between the head and a direction of movement of the disk.