Patents Assigned to Rosemount Engineering Company Limited
  • Patent number: 4678937
    Abstract: A circuit provides electrical isolation from an input signal which has a leading edge and a trailing edge. On the leading edge of the input signal, a first signal is transmitted across an isolation device to provide a first isolated signal representative of the leading edge of the input signal. On the trailing edge of the input signal, a second signal is transmitted across the isolation device to provide a second isolated signal representative of the trailing edge of the input signal. The first and second isolated signals are electrically isolated from and representative of the input signal.
    Type: Grant
    Filed: February 3, 1984
    Date of Patent: July 7, 1987
    Assignee: Rosemount Engineering Company Limited
    Inventor: Timothy D. Price
  • Patent number: 4631519
    Abstract: The relative position of two elements is measured by reading a coded strip 11 fixed to one of the elements. The strip 11 carries code elements in a pseudo-random binary sequence (PRBS) which can be read by a photo-detector array 15. The array 15 and suitable optics if necessary enable enough successive code elements of the PRBS to be read simultaneously to identify the position along the PRBS. The array 15 has several detecting elements for each code element or bit of the PRBS, so that the fine position of transitions or markings of the PRBS can be measured within one PRBS bit length. A comparator 17 compares the output of the array 15 with a portion of the PRBS from a PRBS generator 21. The generated PRBS is serially shifted through a register 18 and a counter 22 stores the number of shifts needed until a match is found. Applications are described in micrometers, pressure sensors, shaft encoders and others.
    Type: Grant
    Filed: April 20, 1984
    Date of Patent: December 23, 1986
    Assignee: Rosemount Engineering Company Limited
    Inventor: James S. Johnston
  • Patent number: 4627902
    Abstract: A resistance thermometer element having a thin layer of platinum metal on an insulating substrate is formed by magnetron sputtering in a gaseous atmosphere containing at least 10% by volume of oxygen. Any balance gas has less than 10% by volume of argon, krypton and xenon. The atmosphere may have up to 100% oxygen with any balance gas being inert to platinum. Air can be used. A planar magnetron may be used.
    Type: Grant
    Filed: April 5, 1984
    Date of Patent: December 9, 1986
    Assignee: Rosemount Engineering Company Limited
    Inventors: James S. Johnston, Leslie Holland, Christopher R. Wright
  • Patent number: 4623800
    Abstract: Clock-controlled dual slope voltage to frequency converter has an integrator supplying a charging ramp to a threshold detector. The slope of the ramp depends on the input voltage to the integrator and the threshold detector is triggered by the ramp to enable a pulse from a clock to generate a constant current discharge pulse. The discharge pulse is fed to the integrator to produce a discharge ramp back below the threshold. The frequency output is taken from the output of the threshold detector to be synchronous with triggering of the detector.
    Type: Grant
    Filed: December 27, 1985
    Date of Patent: November 18, 1986
    Assignee: Rosemount Engineering Company Limited
    Inventor: Timothy D. Price
  • Patent number: 4499373
    Abstract: A differential pressure sensor has a sensing diaphragm mounted in a body. The curvature of the diaphragm is representative of differential pressure across the diaphragm. Monochromatic light is direct from a source at the diaphragm to set up interference fringes which have varying spacings representative of the curvature, in the manner of Newton's rings. The fringes and their spacings are monitored and a computer calculates therefrom the curvature of the diaphragm and thence the pressure difference.
    Type: Grant
    Filed: June 1, 1982
    Date of Patent: February 12, 1985
    Assignee: Rosemount Engineering Company Limited
    Inventor: James S. Johnston
  • Patent number: 4428239
    Abstract: A differential pressure transducer of the diaphragm displacement type uses optical techniques to measure disphragm displacement. White light from a source is conducted by optical fibres to the transducer and interference is produced between light reflected at a thickened region of the diaphragm and a partially reflecting end face of the light conductor which is lapped flat and parallel to the diaphragm surface. The interfering reflected light is conducted back to a prism where it is dispersed onto photo-arrays. The wavelengths of dark fringes in the spectrum are measured to determine the displacement of the diaphragm. Measurements can be made on both sides of the diaphragm and used to eliminate dependence on reflective index.
    Type: Grant
    Filed: October 26, 1981
    Date of Patent: January 31, 1984
    Assignee: Rosemount Engineering Company Limited
    Inventor: James S. Johnston
  • Patent number: 4398194
    Abstract: A differential pressure transducer is a body with a pair of opposed sensing chambers bounded by diaphragms and associated surfaces of the body. The surfaces have conducting layers and form capacitors with the metal diaphragms. The chambers are connected together and fitted with a fixed mass of oil. A signal generating circuit produces electrical signals representing the values of the two sensing capacitors which are fed to a computer to calculate the differential pressure independent of temperature.
    Type: Grant
    Filed: February 25, 1982
    Date of Patent: August 9, 1983
    Assignee: Rosemount Engineering Company Limited
    Inventor: James S. Johnston
  • Patent number: 4347495
    Abstract: An oxygen sensing element has a body of chromium-rich zinc chromite and electrodes in contact with it for sensing the electrical resistance. At elevated temperatures, the resistance varies with oxygen concentration. A rare earth oxide dopant, preferably 15% mole percent Lanthanum 10 oxide, stabilizes and improves performance.
    Type: Grant
    Filed: September 30, 1980
    Date of Patent: August 31, 1982
    Assignee: Rosemount Engineering Company Limited
    Inventors: Donald N. Hunter, Richard J. Brook
  • Patent number: 4190453
    Abstract: A process for preparing a heat-settable casting or moulding composition comprises forming a mixture of a refractory oxide, preferably alumina, and a polyvalent metal polyphosphate, the polyvalent metal being preferably magnesium, aluminium, cobalt or zinc. The mixture is preferably formed by precipitating the polyvalent metal polyphosphate from an aqueous solution of an alkali metal polyphosphate in the presence of the refractory oxide by the addition of a water soluble polyvalent metal salt to the solution.The compositions are useful in making encapsulated or "potted" components such as resistance thermometers and thermocouples.
    Type: Grant
    Filed: April 13, 1978
    Date of Patent: February 26, 1980
    Assignee: Rosemount Engineering Company Limited
    Inventors: Donald N. Hunter, Lesley J. Wyatt
  • Patent number: 4168626
    Abstract: A temperature probe has a tubular sheath open at one end and a mounting body for mounting the probe in an operational location. The sheath is secured to the mounting body by means of a clamping member in screw-threaded engagement with the mounting body and trapping an olive encircling the sheath. The clamping member and mounting body are screwed together to compress the olive onto the sheath and form a fluid-tight seal between the sheath and the mounting body.
    Type: Grant
    Filed: March 7, 1978
    Date of Patent: September 25, 1979
    Assignee: Rosemount Engineering Company Limited
    Inventor: Harry Fullager
  • Patent number: 4164539
    Abstract: A catalytic gas detector is formed as a sandwich and comprises two flat printed film resistance thermometer sensors back-to-back with a layer of thermally insulating material between them. A coating of a suitable catalytic substance covers an exposed flat face of one of the two sensors.
    Type: Grant
    Filed: August 29, 1977
    Date of Patent: August 14, 1979
    Assignee: Rosemount Engineering Company Limited
    Inventor: James S. Johnston
  • Patent number: 4080821
    Abstract: An electric circuit includes three matched resistance thermometer sensors and is responsive to changes in rate of heat loss from at least one of them. The sensors are connected in a series-parallel arrangement to form one arm of a bridge circuit. An amplifier detects imbalance in the bridge and controls current flowing in the bridge to restore balance. Twice as much current flows in one sensor than in the other two, so that the one is maintained hotter. Environmental changes effecting a change in the rate of heat loss from the one sensor are detected as a change in current flowing in the bridge.
    Type: Grant
    Filed: March 28, 1977
    Date of Patent: March 28, 1978
    Assignee: Rosemount Engineering Company Limited
    Inventor: James Stewart Johnston
  • Patent number: 3986385
    Abstract: Apparatus for determination of the freezing point of a liquid or solution has a probe extending into the liquid with means for vibrating the probe. Fixed elements which are cooled, e.g. Peltier plates, are arranged adjacent probe so that a mantle of solid forms on these elements and grows to touch the probe, thereby changing the resonant frequency. This change in resonant frequency is sensed and used to control the cooling so that the probe remains just in contact with a surface where solid is forming, i.e. in liquid at the freezing point. The probe temperature is sensed electrically, e.g. with a resistance thermometer.
    Type: Grant
    Filed: July 16, 1975
    Date of Patent: October 19, 1976
    Assignee: Rosemount Engineering Company Limited
    Inventors: James Stewart Johnston, Trevor Howard Neve
  • Patent number: 3976981
    Abstract: A control system for controlling a number of different variables in accordance with input information has a plurality of separate control channels each including a digital store, preferably a shift register, for storing input and output data and also control parameters appropriate to that channel. The channels are connected sequentially to a common data processing unit which makes use of a common algorithm store. Selection of algorithms for the various channels is effected by a pin board matrix thereby providing a visual display of the selected algorithms. An operator's console has facilities for selecting any channel and displaying information from the channel store on monitors. A key-board enables the operator to change control parameters of the selected channel. Each channel also includes means for analogue-to-digital conversion of input information, digital to analogue conversion of output information and holding means for output analogue data.
    Type: Grant
    Filed: May 14, 1973
    Date of Patent: August 24, 1976
    Assignee: Rosemount Engineering Company Limited
    Inventor: Keith Romilly Roskrudge Bowden
  • Patent number: 3953721
    Abstract: An analogue computer has two or more multiplication modules. Each module provides an output signal representing the product of the magnitude of an analogue input signal to the module and the factor represented by a common multiplier signal controlling the module. Output signals of two or more modules are combined to provide a composite signal. A comparator compares the composite signal with a reference level and adjusts the common multiplier signal so as to maintain the composite signal substantially equal to the reference level. Modules are connected in chains with the output of one module connected to the input of the next module in the chain. Output signals from the various modules represent terms in the polynominal expressions of equations which the computer can solve. Potentiometers allow these output signals to be scaled in accordance with the constant coefficients of the terms.
    Type: Grant
    Filed: February 12, 1975
    Date of Patent: April 27, 1976
    Assignee: Rosemount Engineering Company Limited
    Inventors: James Stewart Johnston, Dennis George Cope
  • Patent number: 3939557
    Abstract: A resistance thermometer sensor is provided by forming a path of electrically conducting material secured on an insulating base. The path is shaped as a loop having two side-by-side portions. A shorting bar connecting across these portions to short circuit part of the loop is adjusted along their length to trim the ice point resistance of the sensor as required. When suitably adjusted, the shorting bar is fastened in position, for example by welding. In one example, the sensor comprises a bifilar helix of resistance wire wound and secured on a cylindrical former.
    Type: Grant
    Filed: January 9, 1975
    Date of Patent: February 24, 1976
    Assignee: Rosemount Engineering Company Limited
    Inventor: Kenneth George Rendle