Abstract: Slowly tapering the cone angle as a function of distance along the cone results in a horn transducer that has a sharp focus in the near field and a large depth of field. The horn is simulated by time delaying the excitation pulse sequence to an annular array. An ultrasonic imaging system, particularly for contact B-scanning, uses an annular array to simulate both a horn transmitter and a fixed-focus receiver. This device has good resolution over a large depth of field and is easy to implement.
Abstract: A high quality velocity signal is generated from an incremental position encoder, thus eliminating the DC tachometer in robot and machine tool closed loop control systems. The encoder signals are used to amplitude modulate the outputs of a high frequency oscillator. Two side band frequencies equal to the sum and difference of the encoder and oscillator frequencies are produced and converted to analog voltages and summed to yield a speed signal. This signal is continuous through zero rate and has a polarity determined by direction of rotation.
Abstract: A robotic machine used in the automatic assembly of mechanical and electrical components is configured to assemble heavy parts at high speeds and is modular; there are one to four degrees of freedom. A motor assembly machine has X, Y, and Z movable axes and a rotational movement .theta. about the Z axis; a gripper or tool is mounted on the lower end of the .theta. axis. The vertical carriage has a rigid elongated housing which is the support structure for the .theta. axis components.
Abstract: Data generated by an encoder with phase quadrature outputs, for instance a displacement transducer in a resistance spot welder control system, is read out of the interface to the computer in a format compatible with computer languages. The quadrature signals are converted to pulses representing positive and negative unit changes of displacement, and fed to an up-down counter which has signed two's complement values at its output. The most recent displacement data is read out while the counter continuously tracks the encoder.
Abstract: The radiation pattern of shaded single element piezoelectric transducers and transducer arrays has reduced side lobe levels. Shading to reduce the intensity of emitted ultrasound at the edges of the transducer relative to the center is realized by varying the electric/acoustic conversion efficiency or polarization of the piezoelectric material, by having different mechanical element lengths, by selectively poling the piezoelectric material to produce poled and unpoled regions, and by control of electrode geometry. The shading of a phased array ultrasonic transducer is described in both lateral dimensions.
Abstract: The pickup and insert tool is used during the automated assembly of small motors and other products that require tie bolts, screws, and similar fasteners. Different length tie bolts are handled without adjusting the tool. The fastener is picked up from a holder and held between a pair of spring loaded jaws. The motion to insert the tie bolt is provided by a movable rod which also accommodates the different lengths of the bolts.
Abstract: A gas tungsten arc welding torch suitable for robotic welding has an improved built-in optical vision sensor which images the weld puddle and weld region on the face of a fiber optic cable; the image is relayed to a video camera and computer to control the torch motion and weld process. The electric arc is much brighter than the area around the arc it is desired to image. A shaped blocking device on the tungsten electrode, such as a molybdenum sleeve or collet set back so that the arc is undisturbed, prevents the arc from being imaged and eliminates image distortions caused by the presence of the bright arc.
Abstract: The thickness of the molten weld nugget is continuously monitored during resistance spot welding, and when proper penetration is achieved the applied current is turned off. An ultrasonic transducer housed in the water cooled lower welding electrode transmits ultrasonic pulses into the workpiece and receives waves reflected at each solid/solid and liquid/solid interface. The position of the latter is tracked by pulse time discrimination of reflected signals; weld nugget penetration is computed using a ratio of times or a pulse time difference.
Abstract: Objects of different sizes and shapes are gripped in a monostable manner by an apparatus which has a single pneumatic power source and has interchangeable jaw assemblies attached to an operating mechanism that provides a linear motion to engage the object. The gripping jaws are selected from a set of three basic types of generic jaws, i.e., nose-shaped jaws and vee-shaped jaws for curved surfaces, and rest button jaws for flat surfaces. Various turbine blades, for instance, are grasped by the airfoil and root using different combinations of these jaw types and have a predictable location relative to the gripping device.
Abstract: The adaptive controller for a resistance spot welder is implemented with a microcomputer and peripherals to handle the monitoring of several process variable inputs and control the welding machine in real time. Before welding power is applied, electrode load, workpiece thickness and dynamic resistance are measured and must fall within predefined limits in order to continue. The workpiece, if necessary, is conditioned to correct fit-up and surface contamination problems by applying power pulses to lower its resistance. The welding power in each half cycle is dynamically adjusted as a function of workpiece thermal expansion and its first derivative to control formation of the weld nugget, and to control the cooling rate and temper the workpiece. During welding the power limits are adjusted in real time to compensate for electrode flattening and shunt effects. The quality of each weld is diagnosed and machine diagnostics are performed.
Abstract: The ultrasonographer changes the frequency of ultrasound pulses emitted from an ultrasonic transducer as a result of adjusting the RF frequency of the transmitter burst exciting the broadband transducer; this adjustment takes place between pulse transmissions, while examining the patient. In a phased array imager utilizing baseband processing of received echo signals, the same adjustment supplies the corresponding frequency to the demodulator circuits. An alternative method of changing the system spectrum is to have a narrow bandwidth receiver whose center frequency is varied over the available bandwidth.
Abstract: The beam characteristics of individual array elements of a linear transducer array are altered by collimation of ultrasonic waves using critical angle effects. A phased array transducer for a medical imaging system with a 90.degree. image sensor has a collimator which is a thin sheet of polyethylene. Acoustic waves whose angle of incidence is greater than the critical angle are totally reflected. Insignificant ultrasonic energy is generated outside of the imaged sector and there is a modest insertion loss over the acceptance region.
Abstract: A control system is provided in which a signal proportional to the actual rotor speed of an induction motor is coupled to a variable gain amplifier. Changes in the commanded gain of the amplifier electronically control the ratio between rotor speed and the output signal amplitude of the variable gain amplifier. The output of the variable gain amplifier determines the commanded stator frequency. Disks optically encoded with a PWM pattern are driven at a speed which corresponds to the commanded stator frequency. Optical sensors read the pattern and provide switching signals to an inverter coupled to an induction motor.
Abstract: An array of electrostatic transducers is fabricated on a monolithic integrated circuit chip having provision for detection, amplification, and signal processing of received echoes. The transducer is multilayered with the form of a parallel plate capacitor, and is made by laterally etching an insulating layer through a small hole in the overlying layer to create a void region, then depositing a sealing layer to seal the etch holes. The upper metallic layers cover the transducer array and other monolithic circuitry and are etched to be interconnections for the various components.
Abstract: The vibration of a moving device which has repetitive movements, for instance a rotary compressor, are sensed at the outer case and analyzed in real time in both the time and frequency plane. For the time analysis the envelope of the signal is generated; for the frequency analysis a fast Fourier transform is performed and separate power spectra for fractions of a revolution are produced. The signatures are compared with those of an acceptable device to identify rejects and abnormalities at a particular position of a moving part.
Abstract: A linear array for rectilinear and sector scan imaging has identical approximately diamond-shaped transducer elements fabricated by making two pairs of straight line cuts at small angles through a piezoelectric slab. The Y-axis radiation pattern (parallel to element length and perpendicular to the array length) has lower side lobe levels than equal sized rectangular elements. No changes in the imager electronics among channels is required, and the shading function may be modified by changing only the transducer.
February 16, 1982
Date of Patent:
January 10, 1984
General Electric Company
Lowell S. Smith, Axel F. Brisken, Michael S. Horner
Abstract: A high pressure metal (sodium) vapor lamp comprises an outer vitreous envelope and an inner ceramic arc tube supported within it. The arc tube contains vaporizable metal in excess of the quantity vaporized in operation and the heat balance determines a cold spot whereat excess metal collects. The temperature of the cold spot determines the vapor pressure and the voltage drop across the lamp which must lie between specified limits. A thermal link is provided to a metal member such as the exhaust tube, the heat loss from which influences significantly the temperature of the cold spot. In completed lamps measuring too low in voltage, such thermal link may be partly severed without breaking open the outer envelope in order to raise the voltage. One convenient way utilizes an auxiliary wire which is cut by aiming a laser beam at it. Another convenient way to reduce the conductive cross section of the thermal link is to use a laser to drill one or more holes through a metallic member comprising the thermal link.
May 4, 1981
Date of Patent:
August 30, 1983
General Electric Company
Francois D. Martzloff, Marshall G. Jones
Abstract: Junction and metal-semiconductor field effect transistors have a sapphire substrate to realize isolation and reduced capacitance, and have a self-aligned gate to minimize source parasitic resistance. A lightly doped, opposite conductivity type region under the channel forces carriers to flow near the silicon surface where mobility is high; this region is depleted at all times by the P-N junction built-in voltage and acts as an insulator. These devices serve as switches in high speed logic applications and as microwave amplifiers.
March 22, 1982
Date of Patent:
July 19, 1983
General Electric Company
William R. Cady, SePuan Yu, John R. Eshbach
Abstract: A conductive multilevel liquid sensor uses conventional integrated circuits such as inverters and voltage comparators as signal detectors, and a flat cable having corrosion-resistant probe conductors of different lengths as the sensing probe assembly. The binary encoded outputs of the signal detectors identify the sensed liquid level. A continuous level control is realized by the addition of timing logic, and sensor operation range is improved by having the voltage at one comparator input be adaptive to the change in liquid conductivity.
Abstract: A high frequency ultrasonic transducer is improved by fabricating the tungsten-polyvinyl chloride composite, which backs the elements, in a specific manner. Small particle size tungsten powder and PVC powder are placed into a high pressure die. Standard processing of the powder mixture includes degasing followed by heating and compressing. To maximize the acoustic attenuation, the pressure applied to the mixture is maintained until it has cooled down. The composite is in a state of elastic compression and spontaneously expands when removed from the die, giving rise to the high levels of acoustic attenuation.