Patents Represented by Attorney Donald R. Campbell

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  • Vertical field effect transistor with improved gate and channel structure
    Patent number: 4262296
    Abstract: A high frequency field effect transistor of gallium arsenide or other III-V semiconductor compounds has a preferentially etched trapezoidal groove structure in the top surface which creates parallel trapezoidal semiconductor fingers that are wider at the top than at the bottom. Schottky gates or junction gates are fabricated within the grooves surrounding the elongated fingers. The vertical conducting channels between the gates are narrow leading to a high blocking gain, and more contact area is available at the top of the device.
    Type: Grant
    Filed: July 27, 1979
    Date of Patent: April 14, 1981
    Assignee: General Electric Company
    Inventors: James R. Shealy, Bantval J. Baliga, Wirojana Tantraporn, Peter V. Gray
  • Quantitative volume blood flow measurement by an ultrasound imaging system featuring a Doppler modality
    Patent number: 4257278
    Abstract: A technique particularly suitable for measuring volume flow rate in the ascending aorta employs real time sector-scan imaging to locate the cross section of interest and align the Doppler beam with the vessel axis. The number of active transmit and receive array transducer elements is varied to electronically tailor the acoustic beam cross section at the required range to be approximately equal to the vessel cross section, which is the sample volume. Mean flow velocity is computed by averaging the spectral components extracted from the sample volume by a Fourier transform processor. Volume flow rate is calculated by multiplying mean flow velocity and estimated area.
    Type: Grant
    Filed: August 24, 1979
    Date of Patent: March 24, 1981
    Assignee: General Electric Company
    Inventors: Emmanuel Papadofrangakis, John A. Fakiris
  • Laminated motor stator structure with molded composite pole pieces
    Patent number: 4255684
    Abstract: Stator structures are fabricated using strip material and moldable magnetic composite, either amorphous metal tape and amorphous flake or similar conventional materials. The laminated core is assembled from identical core sections constructed of nested layers of flat strip, and the moldable material forms the pole pieces after insertion of the coils. Alternately, the pole pieces are produced by bending the laminated tape structure. Shading coils may be added to realize an easily assembled shaded pole motor.
    Type: Grant
    Filed: August 3, 1979
    Date of Patent: March 10, 1981
    Inventors: William R. Mischler, General Electric Company
  • Semi-nondestructive residual stress measurement
    Patent number: 4249423
    Abstract: Residual stress measurements are made using a strain gage and stress relief achieved by local melting of a region of the object being tested by a laser beam or other finely directed heat source. Surface strain is measured dynamically before the heat of the molten region diffuses under the gage and results in thermal stress. The method is semi-nondestructive because the molten region recasts with little loss of material, is rapid, and can be utilized on difficult geometries such as the interior surface of reactor pipe.
    Type: Grant
    Filed: May 11, 1979
    Date of Patent: February 10, 1981
    Assignee: General Electric Company
    Inventors: John R. M. Viertl, Marshall G. Jones
  • Measurement of residual stresses by local melting
    Patent number: 4248094
    Abstract: Residual stress measurements are made using a strain gage and stress relief achieved by local melting of a region of the object being tested by a laser beam or other focused heat source. Surface strain is measured after the molten region resolidifies, and the effect of thermal stress and recast stress is eliminated by subtracting a calibration measurement of an annealed specimen. The method is semi-nondestructive, less costly than existing techniques, and can be used to measure residual stress on the interior surface of pipes.
    Type: Grant
    Filed: May 10, 1979
    Date of Patent: February 3, 1981
    Assignee: General Electric Company
    Inventors: Robert A. Thompson, Hsin-Pang Wang
  • Porous membrane humidity sensor
    Patent number: 4245506
    Abstract: An improved sensor which responds to varying relative humidity by a change in impedance does not fail at 95-100 percent relative humidity. A microporous glass membrane or irradiated-and-etched plastic membrane contains a salt in its pores and has conductive coatings on both surfaces and hydrophobic films on the conductive coatings. At high humidities the pore fills with water and forms a bulge on the end of the pore because water will not wet the hydrophobic film. With proper choice of the pore radius no salt solution spills out.
    Type: Grant
    Filed: September 19, 1979
    Date of Patent: January 20, 1981
    Assignee: General Electric Company
    Inventor: William H. Meiklejohn
  • Scan converter for ultrasonic sector scanner
    Patent number: 4245250
    Abstract: The input data format in a single-sector or multi-sector scanner imaging system is chosen such that angulated scan lines intersect a lateral line at equal increments, and along the scan lines the echo signal is sampled at different rates whereby sampling points are along parallel raster lines. Successive scan lines are stored in adjacent columns of a row-column oriented digital memory. Echo data is read out of memory row by row at a variable rate to convert the read-out data back to sector geometry. The image is displayed in real time in a cathode ray tube.
    Type: Grant
    Filed: September 13, 1979
    Date of Patent: January 13, 1981
    Assignee: General Electric Company
    Inventor: Jerome J. Tiemann
  • Temperature sensing probe for microwave ovens
    Patent number: 4237731
    Abstract: A high impedance four wire temperature sensing system is comprised of a thermistor or other sensor and four leads such that a constant current is impressed on the sensor via two leads and the voltage across the sensor is read via the other two. The sensor and leads have microwave surface resistivity much higher than impedance levels in microwave ovens so that negligible microwave energy is coupled to the sensing system. The high resistance leads in a rigid probe to be inserted into the food and in a flexible cable are electrically conductive iron oxide magnetic tape or are deposited conductors.
    Type: Grant
    Filed: April 9, 1979
    Date of Patent: December 9, 1980
    Assignee: General Electric Company
    Inventor: Rudolph A. Dehn
  • System for monitoring bearings and other rotating equipment
    Patent number: 4237454
    Abstract: A self-powered monitor unit with a tuned mechanical resonator power unit and a radio transmitter is mounted on every piece of rotating equipment being monitored, such as machinery with ball bearings. Bearing vibrations are sensed and the generation of a defect signal triggers the transmission of a radio signal modulated to identify the source. A central station receives and demodulates an emitted radio signal and displays the location with a fault condition. Large numbers of equipment can be monitored conveniently by unattended units.
    Type: Grant
    Filed: January 29, 1979
    Date of Patent: December 2, 1980
    Assignee: General Electric Company
    Inventor: Leslie D. Meyer
  • Reversible variable frequency oscillator for smooth reversing of AC motor drives
    Patent number: 4227138
    Abstract: A variable speed ac motor drive such as a controlled current inverter drive with load angle control generates an inverter frequency command signal which at low speed has a large ripple component and a small dc component representing the desired frequency. A variable frequency oscillator is responsive only to the dc component and supplies timing pulses to a ring counter which generates thyristor gating signals in the forward and reverse phase sequence. Smooth reversing over a wide range of torque is realized, and multipulse operation is inherent at low speeds to modulate the inverter output and minimize cogging torque.
    Type: Grant
    Filed: April 10, 1978
    Date of Patent: October 7, 1980
    Assignee: General Electric Company
    Inventors: Paul M. Espelage, Loren H. Walker
  • Laser welding aluminum to copper
    Patent number: 4224499
    Abstract: Copper and aluminum conductors are butt welded or corner welded by a two-part process involving heating and melting the Cu-Al interface with energy from a pulse laser and simultaneously generating a contact pressure. The laser wavelength is 1.06 micrometers or less and a single 8 millisecond pulse is used. Brittle intermetallics are found in the flash but the narrow fusion zone in the weld is substantially free of intermetallics. High conductivity aluminum is successfully welded to electrolytic tough pitch (ETP) copper wire.
    Type: Grant
    Filed: October 20, 1978
    Date of Patent: September 23, 1980
    Assignee: General Electric Company
    Inventor: Marshall G. Jones
  • Directional detection of blood velocities in an ultrasound system
    Patent number: 4217909
    Abstract: The velocity and direction of the flow of blood and similar liquids, toward or away from the transducer, are measured by coherent demodulation of the received echoes in two quadrature components and subsequent real time processing by a complex Fourier transform processor. A distribution of Doppler frequency shifts and bidirectional velocities are detected and displayed. The preferred embodiment is a duplex imaging system with a sector scanner into which a Doppler modality is incorporated with little added complexity.
    Type: Grant
    Filed: August 23, 1978
    Date of Patent: August 19, 1980
    Assignee: General Electric Company
    Inventors: Emmanuel Papadofrangakis, William E. Engeler
  • Fabrication of front surface matched ultrasonic transducer array
    Patent number: 4217684
    Abstract: A slab of piezoelectric ceramic plated on all surfaces is bonded to quarter wavelength impedance matching layers of glass and plastic. The top surface of the ceramic is slotted and parallel cuts orthogonal to the slots are made through the ceramic and into the glass to delineate an array of elements each with a signal electrode between slots and a wrap-around ground electrode. After making ground connections and flying lead connections to the signal electrodes, the matching layers are fully cut through from the front. A covering or wear plate is attached to the front surface and a relatively large mass of acoustic damping material covers the backs of the elements.
    Type: Grant
    Filed: April 16, 1979
    Date of Patent: August 19, 1980
    Assignee: General Electric Company
    Inventors: Axel F. Brisken, Lowell S. Smith
  • Amorphous metal lamp ballast having a capacitor integral with the magnetic core
    Patent number: 4211957
    Abstract: The magnetic core of a lamp ballast is bifilar wound from inherently thin amorphous metal strip and utilizes the laminations of the magnetic circuit as the plates of a capacitor. The outer yoke of the core encases the coils and is edge-wound from amorphous metal ribbon alternated with insulation to also be the power factor capacitor. The inner core is accordion-pleated or spirally wound and is electrically connected to be the starting capacitor. Cutaways in the inner core cause saturation and shape the lamp current waveform.
    Type: Grant
    Filed: January 31, 1979
    Date of Patent: July 8, 1980
    Assignee: General Electric Company
    Inventors: Robert P. Alley, Theodore R. Haller, Russell E. Tompkins
  • Microwave directional coupler and detector module
    Patent number: 4211911
    Abstract: A module board comprised of a microstrip transmission line, terminating resistors and detectors is mounted over two coupling apertures spaced one quarter guide wavelength along a rectangular waveguide. The microstrip line has a length of five quarters of a wavelength as measured in the secondary line system. Output signals representing forward and reflected power flow in the waveguide are developed by the two detectors. This power sensor is low cost and compact and is suitable for a microwave oven.
    Type: Grant
    Filed: January 16, 1979
    Date of Patent: July 8, 1980
    Assignee: General Electric Company
    Inventor: Rudolph A. Dehn
  • Amorphous metal electric motor with integral capacitor
    Patent number: 4211944
    Abstract: An electric machine with a laminated stator or rotor core made of magnetic amorphous metal ribbon takes advantage of the increased lamination area due to the inherent thinness of the material to utilize the laminations as the plates of a capacitor for starting, running, and/or power factor correction. Two amorphous metal ribbons with alternate insulating layers are wound two-in-hand either helically or spirally to fabricate the cores and more than one amorphous metal core, can be provided and connected as additional capacitors. The preferred embodiment is a single phase permanent split-capacitor motor with integral capacitor.
    Type: Grant
    Filed: June 12, 1978
    Date of Patent: July 8, 1980
    Assignee: General Electric Company
    Inventor: Theodore R. Haller
  • Wear plate for piezoelectric ultrasonic transducer arrays
    Patent number: 4211949
    Abstract: A linear transducer array for 90.degree. or other wide angle sector scans is covered by a body contacting wear plate made of a material such as filled silicone rubber or polyurethane epoxy in which the longitudinal sound velocity is equal to or less than that in the body and in which the acoustic impedance for longitudinal sound waves is approximately equal to that of the body. Refraction, if it occurs, enhances the field of view without reducing the transmission of acoustic energy. The wear plate provides mechanical support for a fragile front surface matched array.
    Type: Grant
    Filed: November 8, 1978
    Date of Patent: July 8, 1980
    Assignee: General Electric Company
    Inventors: Axel F. Brisken, Lowell S. Smith
  • Front surface matched piezoelectric ultrasonic transducer array with wide field of view
    Patent number: 4211948
    Abstract: An ultrasonic transducer array with high sensitivity, for use in water tanks and with human subjects in steered beam imagers to make wide angle sector scans, has narrow transducer elements and one or more quarter-wavelength impedance matching layers on the front surface of each element. The matching layers as well as the piezoelectric ceramic are completely cut thorugh and guide acoustic energy incident at any angle to the ceramic. A continuous covering or wear plate is attached to the matching layers and a continuous damping material can cover the backs of the elements.
    Type: Grant
    Filed: November 8, 1978
    Date of Patent: July 8, 1980
    Assignee: General Electric Company
    Inventors: Lowell S. Smith, Axel F. Brisken
  • High power density brushless dc motor
    Patent number: 4187441
    Abstract: A multiple disk, pancake, self-fed brushless dc motor characterized by high power density has a variable number of interleaved, axially spaced rotor and stator disks. The annular rotor disks are made of high coercive force permanent magnets such as cobalt-samarium and ferrites which do not demagnetize easily. The annular stator disks are yokeless and include a spirally wound laminated magnetic core made of steel strip or amorphous metal ribbon with opposing sets of stator slots and windings on both sides of the core. The permanent magnet machine can be operated as a generator.
    Type: Grant
    Filed: May 30, 1978
    Date of Patent: February 5, 1980
    Assignee: General Electric Company
    Inventor: Wilford R. Oney
  • Duplex ultrasonic imaging system with repetitive excitation of common transducer in doppler modality
    Patent number: 4182173
    Abstract: A duplex imaging system with a common transducer array for both modes of operation satisfies the conflicting bandwidth requirements by single impulse excitation of the transducer in B-scan imaging operation to generate a wide bandwidth ultrasound pulse and multiple impulse excitation at the emission frequency in Doppler mode operation to generate a narrow bandwidth ultrasound phase. The multiple impulse excitation has a variable repetition frequency depending on range to a sample volume and velocity of blood flow. A Doppler modality, in which the frequency shift of echoes caused by flow of blood is measured to derive the flow velocity, is incorporated into a sector scanner with little additional complexity.
    Type: Grant
    Filed: August 23, 1978
    Date of Patent: January 8, 1980
    Assignee: General Electric Company
    Inventors: Emmanuel Papadofrangakis, John A. Fakiris, William E. Engeler