| 序号 | 专利名 | 申请号 | 申请日 | 公开（公告）号 | 公开（公告）日 | 发明人 |
|---|---|---|---|---|---|---|
| 121 | Magnetic field sensor comprising a spin tunneling junction element | US09372960 | 1999-08-12 | US06384600B1 | 2002-05-07 | Reinder Coehoorn |
| A strongly miniaturizable magnetic field sensor is based on four spin tunnel junctions, together forming a Wheatstone bridge. The magnetically sensitive electrode functions as well as a laminated flux concentrator, resulting in a low noise single domain configuration, and allowing for magnetization flipping for offset correction. The very simple design also allows easy definition of the fixed magnetization direction of the counter electrode. Very high output voltage combined with very low power. | ||||||
| 122 | Apparatus for recognizing spin valve head failure due to pin layer magnetic field offset | US09218494 | 1998-12-22 | US06295175B1 | 2001-09-25 | Isamu Tomita; Takao Koshikawa; Toshinori Hoshino; Tadashi Nakamura; Hitoshi Kanai; Hiroaki Ueno |
| When a pin layer magnetic field offset judgment unit judges that a magnetic field in a pin layer of a spin valve head through which a sense current flows in the interference direction has been deviated from a normal direction, a recovery processing unit allows a recovery from the abnormality arising from the magnetic field offset. For example, the direction of the sense current is switched from the interference direction to the assist direction, and the sense current larger than that upon the ordinary reading action is allowed to flow so that the temperature of an antiferromagnetic layer exceeds the blocking temperature, whereby the direction of the magnetic field in the pin layer is modified to the normal direction by the action of a magnetic field generated from the sense current. After the modification, the sense current is returned to have its ordinary value in the interference direction. | ||||||
| 123 | MAGNETIC FIELD SENSOR WITH PERPENDICULAR AXIS SENSITIVITY, COMPRISING A GIANT MAGNETORESISTANCE MATERIAL OF A SPIN TUNNEL JUNCTION | US09373430 | 1999-08-13 | US20010013776A1 | 2001-08-16 | REINDER COEHOORN; KARS-MICHIEL H. LENSSEN; PASCAL J.H. BLOEMEN |
| It is proposed to make thin film magnetic field sensors with perpendicular axis sensitivity, based on a giant magnetoresistance material or a spin tunnel junction, by making use of ferromagnetic layers that have strongly different uniaxial anisotropies and/or have a modified magnetization curve by antiferromagnetic exchange coupling with an auxiliary ferromagnetic layer. A strongly miniaturizable magnetic field sensor is based on four spin tunnel junctions, together forming a Wheatstone bridge. The magnetically sensitive electrode functions as well as a laminated flux concentrator, resulting in a low noise single domain configuration. The very simple design also allows easy definition of the fixed magnetization direction of the counter electrode. Very high output voltage combined with very low power. | ||||||
| 124 | Two step resetting of magnetization of spin valve read head at the row level | US44428 | 1998-03-19 | US5974657A | 1999-11-02 | Ciaran Fox; Hardayal Singh Gill; Virgil Simon Speriosu; Jila Tabib |
| A method is provided for resetting the magnetization of the pinned and hard biasing layers of a spin valve read head at the row level. In a first embodiment of the invention a first magnetic field is applied substantially perpendicular to the air bearing surface (ABS) at room temperature for setting the magnetic moment of the pinned layer substantially perpendicular to the ABS followed by applying a second magnetic field substantially parallel to the ABS for setting the magnetic moments of the hard biasing layers substantially parallel to the ABS. In a second embodiment of the invention the antiferromagnetic pinning layer is also reset. This is done by heating the pinning layer with a current pulse conducted through the leads to the conductive layers of the spin valve head so that localized heating takes place adjacent the pinning layer as contrasted to ambient heating of the spin valve head. Simultaneous with the localized heating the first magnetic field is applied for orienting the magnetic spins of the pinning layer perpendicular to the ABS and resetting the magnetic moment of the pinned layer perpendicular to the ABS in a single domain state. Subsequently, a second magnetic field is applied for resetting the magnetic moment of the hard biasing layer parallel to the ABS in a single domain state. | ||||||
| 125 | Magnetic recording/reproducing device with a function of correcting waveform of magnetoresistive-effect head | US778761 | 1997-01-06 | US5969896A | 1999-10-19 | Kazuhiro Nakamoto; Yoshiaki Kawato; Hiroshi Fukui; Hiroyuki Hoshiya |
| A magnetic recording/reproducing device has an inductive write element provided with a coil and magnetic cores for recording information on a medium, a magnetoresistive read element for transducing a change in a magnetic field leaking from a medium, on which information is recorded, into an electrical signal, a detector for detecting an output signal of the read element, a bias field applying unit for applying a bias field to the read element, and a recording/reproducing operation controller for reproducing information based on an output signal from the read element and for controlling the recording current applying unit based on an inputted signal to record information. The recording/reproducing operation control unit has a stabilizing unit for controlling the bias field applying unit to make an absolute value of the bias field in a state where a magnetic field leaking from the medium is applied to the read element larger than that during a normal reproducing operation. | ||||||
| 126 | Camcorder actuated treatment device for treating a camcorder head | US774726 | 1997-01-03 | US5856900A | 1999-01-05 | Joseph F. Fritsch; Roxanne Y. Fritsch |
| A cleaning device (1) for cleaning a video head and drum of a camcorder consists of a housing (2) for engaging the cassette receiving area of the camcorder. A brush (5) on a carrier arm (3) is urged from a rest position within the housing (2) into cleaning engagement with the head and drum under the control of a control mechanism (7). The control mechanism (7) is powered by a drive spindle in the cassette receiving area. A retaining latch (10) secured in the housing (2) consists of a camming member (14) for engaging the carrier arm (3) for retaining the carrier arm (3) and the brush (5) in the rest position. A portion (30) of the retaining latch (10) is resilient for urging the retaining latch (10) downwardly for retaining the carrier arm in the rest position. An engagement member (25) on the retaining latch (10) engages a light post (28) in the cassette receiving area as the housing (2) is being lowered into the cassette receiving area for releasing the retaining latch (10). | ||||||
| 127 | Magnetic reinitialization of thin film magnetoresistive reproducing heads at the suspension level of media drive manufacturing | US462348 | 1995-06-05 | US5783981A | 1998-07-21 | Samir Elias Abboud; Nickolas Christopher Apuzzo; Jeffrey Bernard Brown; Earl Albert Cunningham; David Malcolm Hannon; Raymond Patrick Mallette; Paul Sheldon Tyler; Steven Harry Voss; Albert John Wallash |
| The magnetic states of MR reproducing heads are reinitialized during media drive manufacturing by applying initializing magnetic fields to the transducers after they have been manufactured and incorporated into media drive assemblies. | ||||||
| 128 | Method using a biasing pattern on a magnetic storage media to reduce MR head noise | US438643 | 1995-05-10 | US5696641A | 1997-12-09 | Roger G. Bailey |
| The magnetic recording system of the present invention relaxes/reduces the magnetic energy in a magnetic recording head at the end of a write operation. In one embodiment, the magnetic recording system (10) includes a magnetic recording media (18), a recording head (14), and a biasing pattern (64) stored along a portion of the media (18). The biasing pattern (64) provides a biasing effect on the head (14) that provides controlled reduction of the magnetic energy domains in the head (14). | ||||||
| 129 | Method for driving magneto-resistive element | US607563 | 1996-02-27 | US5689225A | 1997-11-18 | Yutaka Soda; Munekatsu Fukuyama; Jin Sato; Kiyoshi Ota |
| A method for driving a magneto-resistive effect element in which a bias magnetic field is applied by a bias conductor fed with a bias current to a magneto-resistive effect element whose resistivity is changed with an impressed magnetic field, wherein the improvement comprises supplying to said bias conductor a pulsed initial current having a pulse crest value higher than the bias current value prior to supplying said bias current. The MR head can be operated with MR characteristics with stable output and with highly sensitive MR characteristics. | ||||||
| 130 | Magnetic reinitialization of thin film magnetoresistive reproducing heads at the suspension level of media drive manufacturing | US471505 | 1995-06-06 | US5664319A | 1997-09-09 | Samir Elias Abboud; Nickolas Christopher Apuzzo; Jeffrey Bernard Brown; Earl Albert Cunningham; David Malcolm Hannon; Raymond Patrick Mallette; Paul Sheldon Tyler; Steven Harry Voss; Albert John Wallash |
| The magnetic states of MR reproducing heads are reinitialized during media drive manufacturing by applying initializing magnetic fields to the transducers after they have been manufactured and incorporated into media drive assemblies. | ||||||
| 131 | Magnetically stable shields for MR head | US366940 | 1994-12-30 | US5515221A | 1996-05-07 | Hardayal S. Gill; Tsann Lin |
| First and second shield layers of a read head are constructed of a lamination of NiMn and Fe-based layers to improve the performance of the shield layers when they are subjected to high external fields, such as from the pole tips of a write head combined therewith. Without lamination with one or more NiMn layers, many shield materials do not return to the same domain configuration after excitation from an external field. The result is that the Fe-based material assumes a different domain configuration after each excitation which changes the bias point of the MR sensor of the read head. By laminating with NiMn, the uniaxial anisotropy of the material can be increased to provide uniform domain configuration and exchange pinning between shield material NiMn returns the material to the same configuration after each external field excitation. The invention further provides fine tunings of the magnetic properties of the shield layer by various combinations of the Fe-based layers and/or the NiMn layer with NiFe layers. | ||||||
| 132 | Device for switching a video tape recorder head to write/read mode | US100665 | 1993-07-30 | US5483390A | 1996-01-09 | Jean-Luc Jaffard; Yann Desprez-Le Goarant |
| A device for switching a read head from a write mode to a read mode includes a voltage ramp generating circuit, generating and outputting a voltage ramp after a write operation; a variable current source for discharging an initial current of the read head, wherein a current output by the current source is controlled proportionally to the slope between the beginning of the voltage ramp and a first threshold of the ramp, the current source having an initial maximum value higher than the initial current of the head; and an accentuating circuit for accentuating the ramp slope between the beginning of the ramp and a time when the current output by the variable current source becomes equal to the initial current present in the head. | ||||||
| 133 | Atomic layered materials and temperature control for giant magnetoresistive sensor | US56003 | 1993-04-30 | US5440233A | 1995-08-08 | Rodney T. Hodgson; Paul M. Marcus; Victor L. Moruzzi |
| An apparatus and method for detecting a magnetic field has been described incorporating a material which switches from an antiferromagnetic order to a ferromagnetic order upon the application of a magnetic field and wherein the material is FeRh, FeRu, FePd or MnPt, a heating element for controlling the temperature of the material and a current source for sensing the change of resistance of the material to determine when the material is ferromagnetically ordered. The invention overcomes the problem of small changes in resistance of magnetoresistive sensors operating in only the ferromagnetic order. | ||||||
| 134 | Individual MR transducer head/disk/channel adaptive bias current system | US168630 | 1993-12-16 | US5412518A | 1995-05-02 | Jodie A. Christner; Earl A. Cunningham; Gregory J. Kerwin; Joe M. Poss |
| A method and apparatus is disclosed for adaptively controlling the biasing current applied to magnetoresistive (MR) read heads within a magnetic disk drive to provide optimized bias for each head/disk/channel component combination. An optimized bias current for each head is ascertained and stored on the disk surface at the time of manufacture. During each power up operation the values are transferred to random access memory which is accessed during the execution of each head switch command to apply bias current in accordance with the optimized value to the active MR head. Periodic reoptimization and updating of the stored values is effected by general error measurement circuitry that forms a part of the device control system and is invoked to perform the reoptimization upon the occurrence of an event such as a predetermined duration of power on operation subsequent to the last reoptimization procedure. | ||||||
| 135 | Throat height control during lapping of magnetic heads | US675096 | 1991-03-22 | US5214589A | 1993-05-25 | George H. Tang |
| During a lapping operation to obtain an optimum throat height for a thin film magnetic head, an M-H looper circuit is coupled directly to the head coil for measuring the magnetization and saturation current of the head in response to a given drive current. An amplitude modulated analog output signal is digitized and the resultant digital number is compared to stored data signals which are representative of optimum throat heights for the design of the head being lapped. The lapping operation is controlled in response to the difference signals obtained by the comparison. | ||||||
| 136 | Self-initialization of short magnetoresistive sensors into a single domain state | US441689 | 1989-11-27 | US5027243A | 1991-06-25 | Hardayal S. Gill; James A. Brug |
| A a dual element magnetoresistive sensor that uses the longitudinal field produced by the sense/bias currents to initialize the elements into a stable antiparallel state. The dual element magnetoresistive sensor comprises two magnetoresistive elements having first and second conductors coupled thereto. The first and second conductors are oriented in the same direction as the magnetoresistive elements in their contact areas. A third conductor is disposed between and coupled to the two magnetoresistive elements at their opposite ends. The third conductor is oriented transverse to the directions of the first and second sensor elements, and is adapted to conduct current therethrough in a direction transverse to the currents conducted by the first and second conductors. Currents conducted by all three conductors self-initialize the magnetoresistive elements into a single domain state. Also, the current flowing in the third conductor creates an anti-parallel longitudinal field in the two sensor elements that is oriented in the same direction as closure fields present in the magnetoresistive elements. These fields ensure that a single domain state is produced in the magnetoresistive elements. An alternative design for the third conductor employs one conductor portion that provides a current distribution that initializes the sensor. This current distribution initializes the sensor. Another conductor portion is used during reading and provides a current distribution that is similar to the distribution produced by the first and second conductors. This ensures that the across-the-track response is symmetric. A small fraction of the sense current flows in the initializing conductor portion to provide stabilization during reading. | ||||||
| 137 | Cassette device for demagnetizing the magnetic head in a cassette-type recorder | US322465 | 1989-03-13 | US4992902A | 1991-02-12 | Sachima Tani |
| A head demagnetizing device has an overall configuration similar to a standard cassette. Within the case is a demagnetizing electromagnet disposed such that it will be juxtaposed to the head to be demagnetized when the cassette-type device is inserted within a tape recorder. Also included in the case are an electrical system for exciting the electromagnet, a switch for connecting the electromagnet to the circuit for exciting the electromagnet, and an operating member that slides with respect to the electromagnet to activate the switch. | ||||||
| 138 | Demagnetization of thin film magnetic recording transducers utilizing a decreasing AC current | US267144 | 1988-09-09 | US4970621A | 1990-11-13 | Samuel H. Gailbreath; Ralph F. Simmons |
| Noise in the readback signal of a magnetic recording device resulting from spurious pulses in the readback signal produced by transitions of the magnetic remanent state of the yoke in the read/write transducer is eliminated by controlling the occurrence of the spurious pulses. Immediately following the completion of the write process, a decreasing amplitude alternating current is applied to the read/write coil of the transducer to drive the yoke remanent state to a stable or zero remanent state prior to the commencement of the read process. | ||||||
| 139 | Demagnetizer for a magnetic head of a cassette tape recorder | US289410 | 1988-12-21 | US4849843A | 1989-07-18 | Motoyoshi Fujita; Akikazu Kunuki; Noboru Uemura; Tsutomu Kotani; Shunpei Saeki; Toshiharu Kawano |
| A magnetic head of a cassette tape recorder set is demagnetized by a demagnetizer mounted in a tape cassette housing. The demagnetizer has an erase head which faces with the magnetic head which is subject to a demagnetizing action, a pair of rotatable rings which engage with spindles of the tape recorder set, energizing means for energizing said erase head with AC decreasing current, and coupling means for coupling said rings for simultaneous rotation of the rings. | ||||||
| 140 | Eraser and cleaner set | US3435300D | 1966-12-28 | US3435300A | 1969-03-25 | SATO KEISUKE |
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