Magnetic Patents (Class 365/66)
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Patent number: 6256224Abstract: A write circuit for a large array of memory cells of a Magnetic Random Access Memory (“MRAM”) device. The write circuit can provide a controllable, bi-directional write current to selected word and bit lines without exceeding breakdown limits of the memory cells. Additionally, the write circuit can spread out the write currents over time to reduce peak currents.Type: GrantFiled: May 3, 2000Date of Patent: July 3, 2001Assignee: Hewlett-Packard CoInventors: Frederick A Perner, Kenneth J Eldredge, Lung T Tran
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Patent number: 6236586Abstract: A micro magnetic core memory having a magnetic core, which serves as a storage medium, a coil, which is located in close vicinity to the magnetic core and magnetizes the magnetic core, and a sensor, which is located in close vicinity to the magnetic core and detects polarity of magnetization of the magnetic core. The micro magnetic core memory has the effects in that the inputting and the outputting of information can be carried out quickly, in that a high degree of integration can be achieved easily and a storage device having a large capacity can be produced at a low cost, and in that the stored information is not lost when the supply of electric power is turned off.Type: GrantFiled: April 8, 1998Date of Patent: May 22, 2001Inventor: Masayuki Morisaki
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Patent number: 6229729Abstract: A non-volatile RAM device is disclosed which utilizes a plurality of ferromagnetic bits (8) each surrounded by a write coil (15) for directing the remnant polarity thereof is disclosed. The direction of magnetic remnance in each bit (8) is dictated by the direction of a current induced into write coil (15). Further, a magneto sensor (9) comprising a magneto resistor (18) coupled to a diode (26) is placed approximate each bit (8). The magneto resistor (18) is coupled to a sense line (20), and receives current at a first point of attachment, and returns current at a second point of attachment. The current passing across magneto resistor (18) is biased in a direction either right or left of the original current flow direction. If current is biased toward the anode end of diode (26) then it is complimentary to the preferred flow direction of diode (26), and flows easily there across.Type: GrantFiled: February 29, 2000Date of Patent: May 8, 2001Assignee: Pageant Technologies, Inc. (Micromem Technologies, Inc.)Inventor: Richard M. Lienau
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Patent number: 6219274Abstract: The present invention relates to a ferromagnetic tunnel magnetoresistance effect element having a multilayered structure comprising a tunnel barrier layer and a first and a second ferromagnetic layer formed to sandwich the tunnel barrier layer therebetween, wherein the tunnel barrier layer is formed as an oxide film obtained by oxidizing a non-magnetic metal layer according to a radical oxidation method. Thus, there can be obtained a ferromagnetic tunnel magnetoresistance effect element which is excellent in productivity and quality stability and highly excellent in TMR effect.Type: GrantFiled: November 12, 1999Date of Patent: April 17, 2001Assignee: TDK CorporationInventors: Koji Shimazawa, Satoru Araki, Haruyuki Morita
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Patent number: 6191989Abstract: A current sensing amplifier for detecting a small current difference between a pair of variable resistance loads comprises a first amplifier and a second amplifier. The first amplifier comprises a voltage clamp including first and second outputs, the voltage clamp being coupled to the pair of variable resistance loads and substantially fixing a predetermined voltage across the variable resistance loads, the voltage clamp transferring the measured current difference to the first and second outputs. The first amplifier further includes a differential current source coupled to the first and second outputs. The second amplifier includes first and second inputs and an output, the first and second inputs being coupled to the first and second outputs, respectively, of the first amplifier.Type: GrantFiled: March 7, 2000Date of Patent: February 20, 2001Assignee: International Business Machines CorporationInventors: Wing Kin Luk, William Robert Reohr, Roy Edwin Scheuerlein
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Patent number: 6166944Abstract: A data storing apparatus in which a magnetic storing means includes magnetic memory cells for memorizing data of a first value or a second value. Input data is written to the memory cells separately or simultaneously by electromagnetic induction. One or more magnetic memory cells are selected, with respect to which the data is to be read or written. Each magnetic memory cell has a ferromagnetic body holding the data of the first value or the second value in accordance with direction of magnetization or magnetizing force thereof. The current control means performs the reading or writing of the data with respect to the selected magnetic cells. The current control means comprises semiconductor devices and controls current therethrough in both directions.Type: GrantFiled: April 16, 1999Date of Patent: December 26, 2000Assignee: Kyoto UniversityInventor: Hiroyuki Ogino
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Patent number: 6134139Abstract: A magnetic memory with enhanced half-select margin includes an array of magnetic memory cells each having a data storage layer with an easy axis and an array of conductors each having an angle of orientation with respect to the easy axes that is preselected to enhance half-select margin in the magnetic memory. The angle of orientation is such that the longitudinal write field is enhanced and the perpendicular write field is minimized in a selected memory cell. The magnetic memory cells optionally includes a structured data storage layer including a control layer that minimizes the likelihood of half-select switching in the unselected magnetic memory cells.Type: GrantFiled: July 28, 1999Date of Patent: October 17, 2000Assignee: Hewlett-PackardInventors: Manoj K. Bhattacharyya, James A. Brug
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Patent number: 5982658Abstract: A magnetoresistive memory array which has a row of active sense lines with each sense line including magnetoresistive bits and word lines extending over the bits. Each active sense line ending in a termination bit having a configuration selected to cause an adjacent bit to experience a magnetic field similar to that experienced by the remaining bits in the sense line. An inactive sense line located at each end of the row of active sense lines.Type: GrantFiled: October 31, 1997Date of Patent: November 9, 1999Assignee: Honeywell Inc.Inventors: Lonny L. Berg, Paul W. Cravens, Allan T. Hurst, Tangshiun Yeh
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Patent number: 5982660Abstract: A magnetic memory cell including a data storage layer having an easy axis and a reference layer having an orientation of magnetization which is pinned in a direction that is off-axis with respect to the easy axis. This structure increases the signal obtainable during read operation on the magnetic memory cell notwithstanding the effects of magnetizations in the edge domains of the data storage layer. In addition, this structure allows high MRAM densities to be achieved using square-shaped memory cell structures.Type: GrantFiled: August 27, 1998Date of Patent: November 9, 1999Assignee: Hewlett-Packard CompanyInventors: Manoj K. Bhattacharyya, James A. Brug
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Patent number: 5838607Abstract: Spin polarized apparatus includes a spin polarizing section of magnetic material with an electron input port and a polarized electron port and a transport section of magnetic material with a polarized electron input port electrically coupled to the polarized electron port of the polarizing section and an electron output port. Electrons traversing the polarizing section all have similar spin directions at the output dependent upon the magnetization direction of the polarizing section. Electrons traversing the transport section all have spins in a first direction at the output. The cell has a low resistance when the magnetization direction of the polarizing section is in the first direction (electrons entering the transport section all have spins in the first direction) and a high resistance when the magnetization direction is in an opposite direction (electrons entering the transport section all have spins in the opposite direction).Type: GrantFiled: September 25, 1996Date of Patent: November 17, 1998Assignee: Motorola, Inc.Inventors: Xiaodong T. Zhu, Saied N. Tehrani, Eugene Chen, Mark Durlam
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Patent number: 5831920Abstract: A new and improved magnetic device is provided for memories and sensors. A magnetic random access memory (MRAM) device (20) includes a storage element (21) for magnetically storing states and an amplifier (25) for sensing the states stored in the storage element. A circuit (27) for dissipating electrical charges are coupled to inputs (23,24) of the amplifier (25) to discharge electrical charges applied to the inputs (23,24) of the amplifier (25). The charge dissipating circuit (27) includes junctions (271-274) which are typically connected in series between power (255) and common (257) lines. Electric charges applied to the inputs (23,24) of the amplifier (25) is discharged through the junctions (271-274).Type: GrantFiled: October 14, 1997Date of Patent: November 3, 1998Assignee: Motorola, Inc.Inventors: Eugene Chen, Saied N. Tehrani, Mark Durlam, Peter K. Naji
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Patent number: 5793697Abstract: A sensing circuit reads the magnetic state of individual memory cells making up a nonvolatile magnetic random access memory (MRAM) array. Each memory cell is a magnetic tunnel junction (MTJ) element and a diode electrically connected in series. Each MTJ is formed of a pinned ferromagnetic layer whose magnetization direction is prevented from rotating, a free ferromagnetic layer whose magnetization direction is free to rotate between states of parallel and antiparallel to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier between and in contact with the two ferromagnetic layers. The memory cells in the array are controlled by only two lines, and the write currents to change the magnetic state of an MTJ, by use of the write currents' inherent magnetic fields to rotate the magnetization of the free layer, do not pass through the tunnel barrier layer.Type: GrantFiled: February 18, 1997Date of Patent: August 11, 1998Assignee: International Business Machines CorporationInventor: Roy Edwin Scheuerlein
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Patent number: 5757056Abstract: A double tunnel junction is disclosed that can be used as a magnetic sensor or as random access memories. The preferred embodiment comprises three magnetic metal materials separated by two insulating layers. A current is passed through the first tunnel junction thereby developing a voltage in the second junction. The resistance of this device can be changed over a 100% when an external magnetic field of just a few gauss is applied.Type: GrantFiled: November 12, 1996Date of Patent: May 26, 1998Assignee: University of DelawareInventor: Siu-Tat Chui
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Patent number: 5757695Abstract: A multi-layer magnetic memory cell is provided, with magnetic vectors aligned along a length of the cell. To align the magnetic end vectors, an ellipsoidal shape is formed at the ends of the memory cell. Magnetic vectors aligned along the length prevent from forming high fields and magnetic poles at the discontinuity or ends of the layers. The memory cell with the ellipsoidal shape shows a constant magnetic resistance of the magnetic cell when a magnetic field is applied to the cell and attains a reduction of power consumption for the magnetic cell.Type: GrantFiled: February 5, 1997Date of Patent: May 26, 1998Assignee: Motorola, Inc.Inventors: Jing Shi, Theodore Zhu, Saied N. Tehrani
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Patent number: 5602802Abstract: The present invention relates to a medication reminder system, apparatus and method for notifying patients of the correct times during the day for taking a medicine. The system provides a portable module carried by the patient that alerts the patient to the time that a medication should be taken. The portable module is programmed by an operator at a programming station to provide the specific times for taking the medication.Type: GrantFiled: November 14, 1994Date of Patent: February 11, 1997Assignee: Timely Devices Inc.Inventors: Peter Leigh-Spencer, James Baker
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Patent number: 5504699Abstract: A nonvolatile analog magnetic memory includes a substrate comprised of saturable and desaturable magnetic domains at distinguishable fixed locations, a bi-directional drive circuit to selectively write data to the magnetic domains by first saturating a selected magnetic domain with current flowing in one direction, followed by desaturating the magnetic domain with current flowing in the reverse direction of the saturating current, lowering the magnetic flux density to a level corresponding to the magnitude of an analog input electrical signal within a range of magnetic flux density levels between a zero point and a full scale point, sensors and a sensor select circuit to select a magnetic domain and nondestructively respond to the magnitude of the magnetic flux for the chosen magnetic domain, producing an electrical output signal corresponding to the magnetic flux for the chosen magnetic domain.Type: GrantFiled: April 8, 1994Date of Patent: April 2, 1996Inventors: Stuart E. Goller, Frank Powell
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Patent number: 5374472Abstract: A ferromagnetic .delta.-Mn.sub.1-x Ga.sub.x thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of .delta.-Mn.sub.1-x Ga.sub.x overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of .delta.-Mn.sub.1-x Ga.sub.x and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4 .+-.0.05.Type: GrantFiled: January 4, 1994Date of Patent: December 20, 1994Assignee: The Regents, University of CaliforniaInventor: Kannan M. Krishnan
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Patent number: 5329486Abstract: A ferromagnetic memory circuit (10) and a ferromagnetic memory device (15) which has a substrate (42). Within the substrate (42), a first current electrode (44) and a second current electrode (46) are formed. A control electrode (50) is formed to control current flow between the first and second current electrodes (44 and 46). A ferromagnetic region (68) is used to store a logic value via magnetic flux. Two conductive layers (62 and 70) and a conductive spacer (78) form a sense conductor for device (15). The sense conductor is used to externally provide the logic value stored in the device (15). A conductive layer (82) forms a program/erase line for altering the logic value stored in the device (15). A logic one or a logic zero is stored in ferromagnetic region (68) depending upon a direction and a magnitude of current flow through conductive layer (82).Type: GrantFiled: July 23, 1993Date of Patent: July 12, 1994Assignee: Motorola, Inc.Inventor: Craig S. Lage
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Patent number: 4953123Abstract: A control signal used to write access or read access and data are transmitted between a write/read unit and a memory module by a contactless coupling using induction coils. The write/read unit multiplexes a control signal consisting of three signals including a power source signal, sync clocks, and enable clocks using frequency modulation and supplies the resultant multiplexed signal to one end of the induction coil for transmission. The write/read unit frequency modulates access data and supplies same to the other end of the same induction coil for transmission. The transmitting coil in the memory module allows the signal which is obtained by adding an access signal to the control signal to be induced in the coil for reception in the write/read unit. The read data from the memory module is frequency modulated and sent from the memory module to the write/read unit by using the transmitting and receiving coils for a down-signal which is used only to read out data.Type: GrantFiled: January 17, 1989Date of Patent: August 28, 1990Assignee: Tokyo Keiki Company, Ltd.Inventors: Kunihiko Takeuchi, Masao Oba, Shinichi Horinouchi
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Patent number: 4918655Abstract: A component metallization interconnection system in a monolithic integrated circuit system for providing electrical interconnections between circuit components and for providing magnetic interaction regions for information storage.Type: GrantFiled: February 29, 1988Date of Patent: April 17, 1990Assignee: Honeywell Inc.Inventor: James M. Daughton
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Patent number: 4856177Abstract: A tool holder is enclosed in a rack which is moved by a belt for automatic tool exchange. A stopper member provided for the rack is fitted into a positioning groove formed in a flange portion of the tool holder, thereby preventing the rotation of the holder. A magnetic induction coupling apparatus is buried in the bottom of the tool holder positioning groove. A magnetic induction coupling apparatus of a reader/writer disposed at the external position is arranged so as to face the magnetic induction coupling apparatus of the tool holder. Information is written into or read out of a memory module attached in the tool holder by way of the magnetic induction coupling between both of those coupling apparatuses. The stopper member of the rack is arranged between the magnetic induction coupling apparatus of the tool holder and the magnetic induction coupling apparatus of the reader/writer and has a magnetic material to magnetically couple these coupling apparatuses.Type: GrantFiled: February 4, 1988Date of Patent: August 15, 1989Assignee: Tokyo Keiki Company Ltd.Inventors: Kunihiko Takeuchi, Masao Oba, Shinichi Horinouchi
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Patent number: 4809426Abstract: A memory is built in a tool holder to which a working tool such as drill or the like is attached. Various tool information such as kind of tool, dimensions of tool, tool use time, and the like is written into the memory. The tool holder having the memory therein is coupled with an external unit by contactless coupling means which doesn't need any electrical coupling, thereby allowing the tool information to be written into or read out of the memory. The information is transmitted between the memory in the tool holder and the external unit by way of the optical or magnetical coupling. The memory built in the tool holder consists of a non-volatile memory such that the memory content is not erased even if the power supply is shut off.Type: GrantFiled: October 24, 1986Date of Patent: March 7, 1989Assignee: Tokyo Keiki Company, Ltd.Inventors: Kunihiko Takeuchi, Hiroshi Nogi
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Patent number: 4672183Abstract: Device for reading and cancelling thin film areolae of material having uniaxial, magnetic anisotropy and deposited on credit cards or the like, comprising: (i) at least one head including a reading probe formed by a support member carrying at least an assembly formed by an excitation winding associated to a detection winding, said windings being wound in orthogonal relationship to each other around said support member; and at least a pair of cancellation electrodes assembled at the intersection area of said windings and adapted to provide an electric arc therebetween and to be faced to the areolae of the material to be examined and (ii) circuit means for producing the excitation current and for receiving the response signal representative of the characteristics of the material in the areola under examination, and for effecting a comparison of the phase and the amplitude of said signal with reference signals as well as for detecting eventually the rotation by 180.degree.Type: GrantFiled: October 22, 1984Date of Patent: June 9, 1987Assignee: I.P.M. Industria Politecnica Meridionale S.p.A.Inventor: Paolo De Feo