Patents Assigned to Leeds & Northrup Company
  • Patent number: 4034610
    Abstract: A differential pressure measuring device of the three diaphragm type is disclosed in which the measuring in diaphragm is isolated from the substance being measured by a pair of sealing diaphragms. The measuring diaphragm is included in a cell assembly that provides overrange protection for the measuring diaphragm and isolation of the measuring diaphragm from the influence of static pressure induced housing strains.
    Type: Grant
    Filed: November 15, 1976
    Date of Patent: July 12, 1977
    Assignee: Leeds & Northrup Company
    Inventors: Joseph Montgomery Biddle, Richard Malcolm Hickox
  • Patent number: 4008386
    Abstract: A removable control signal is provided which varies as the product of a gain constant times the control error and has means for increasing the gain constant as a time integral of the error. The integral is reset to zero, thus making the gain constant zero, when the error crosses zero to avoid an excessive build-up of the value of the control signal as when the error fails to promptly correct itself.
    Type: Grant
    Filed: January 13, 1976
    Date of Patent: February 15, 1977
    Assignee: Leeds & Northrup Company
    Inventor: Charles Warren Ross
  • Patent number: 3998591
    Abstract: A spectrochemical analyzer utilizing a transparent medium such as quartz which has a color reagent coating the surface. When light is directed into the transparent medium, the magnitude of internal surface reflection varies with the change in absorptivity resulting from a color change in the reagent in response to a change in the chemical condition of the sample. By measurement of the light transmitted by the transparent medium the chemical condition of the sample is measured.
    Type: Grant
    Filed: September 26, 1975
    Date of Patent: December 21, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Edgar Lawrence Eckfeldt
  • Patent number: 3989917
    Abstract: A thermal print head produced by a multilayer process is disclosed. Six of the seven bar-segments of the figure "8" produced by resistive deposits are bounded on the outside by conductive deposits and on the inside by the internal areas of the figure "8" while the seventh is bounded by the internal areas of the figure "8". The peripheral segments are heated selectively by conduction between selected bar-segments and associated internal areas at a particular time while the internal areas are energized to heat the central segment at another time. Each internal area has a single electrical connection to the external switching circuitry.
    Type: Grant
    Filed: October 1, 1975
    Date of Patent: November 2, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Albert Ernst Paschkis
  • Patent number: 3987493
    Abstract: A hot stylus using a mandrel of soft material having good heat conductivity and good electrical conductivity is used to carry heat to the writing end of the mandrel. That end fits in an aperture of a jewel bearing surface which rides on the heat sensitive paper. The mandrel is soldered in a groove along a thermistor having a positive temperature coefficient. The mandrel also provides one electrical connection to the thermistor. The other electrical connection is by way of a foil contact soldered to an opposite face of the thermistor. That assembly is potted and assembled on a circuit board which provides the electrical leads from the stylus body to which the foil is soldered and from the mandrel itself.
    Type: Grant
    Filed: March 19, 1975
    Date of Patent: October 19, 1976
    Assignee: Leeds & Northrup Company
    Inventors: Curtis R. Johnson, Albert E. Paschkis
  • Patent number: 3980543
    Abstract: An assembly for insertion in a bath of molten material to form therewith an electrochemical cell for determining the concentration of a constituent of the bath. The assembly is of the type including a body structure of refractory material from which protrudes a first electrically conductive element providing means for establishing an electrical connection with the bath and a reference electrode structure separated from the bath by means of a rigid electrolyte material. Reference electrode structures of this general type may be comprised of a closed end tube of electrolyte material or a tube of electrically non-conductive refractory material having a pellet of electrolyte material closing the immersion end thereof to separate the material of the bath from the means establishing a reference potential.
    Type: Grant
    Filed: December 4, 1974
    Date of Patent: September 14, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Edgar L. Eckfeldt
  • Patent number: 3972681
    Abstract: A flow-through thermal detector for determining the temperature change resulting from a reaction in a fluid stream includes a pair of parallel fluid paths one of which carries the fluid stream in which the reaction occurs while the other carries a similar fluid without the occurrence of a reaction. The detector includes a temperature sensor for each path. The first of the sensors is mounted to sense the temperature of the reacting stream after said reaction has occurred while the second of the sensors is mounted to sense the temperature of the non-reacting stream at a point in its flow path comparable to that at which the first sensor is mounted. A heat shield is provided surrounding the parallel paths and the heat shield is controllable to a predetermined temperature. Preheating of the streams is carried out by a preheating means positioned within the heat shield to receive the fluid stream entering the shield.
    Type: Grant
    Filed: July 14, 1975
    Date of Patent: August 3, 1976
    Assignee: Leeds & Northrup Company
    Inventors: Peter Joseph Clack, Herman Wesley Levin, George Clarence Mergner
  • Patent number: 3973184
    Abstract: An improved thermocouple circuit condition detector for use in a measuring system requiring simultaneous analog trend recording and analog to digital conversion is disclosed. For analog to digital conversion the circuit testing period must be very short to fit in the time interval between conversions. For analog trend recording there should be no interruption of the analog circuit during the testing period and there should be no analog errors introduced by the testing circuit. All of these requirements are achieved by a novel pulse comparison circuit wherein a pulse by way of a direct path is applied as one input to a differential amplifier while that same pulse by way of the input terminal of the measuring amplifier which is connected to the ungrounded thermocouple lead, is applied to the other input of the differential amplifier. The detector alternately checks for open circuit and short circuit conditions.
    Type: Grant
    Filed: January 27, 1975
    Date of Patent: August 3, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Ervin T. Raber
  • Patent number: 3953188
    Abstract: There is disclosed a system for controlling the cooling of the molds in a glass forming machine which involves compensating the pressure set point for the control of the cooling air to correct for changes in the temperature of the cooling air and changes in the mass flow rate of the glass. During maximum and minimum flow conditions for the cooling air the heat transfer equilibrium between the coolant and the parisons being cooled is modified as by modifying the set points of the temperature controllers on the feeder supplying the forming machine or alternatively by changing the speed of the forming machine so that the parisons tend to stay at the desired temperature with the limited range of coolant supply.
    Type: Grant
    Filed: May 5, 1975
    Date of Patent: April 27, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Harry A. Fertik
  • Patent number: 3950992
    Abstract: An immersion molten metal sampling device of a type usable to obtain a sample of molten steel from a furnace and to measure the temperature of the molten metal in the furnace. The device includes a high density monolithic ceramic mold capable of obtaining a flat, rectangular shaped sample of the molten metal for spectrographic analysis as well as a pin sample for combustion analysis. The construction of the sampler avoids contamination of the sample by using gas permeable substances that are gaseous inert at the temperature of the molten metal while at the same time eliminating problems due to leakage of the molten metal through vent passages and seams in the mold.
    Type: Grant
    Filed: August 27, 1975
    Date of Patent: April 20, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Richard James Hance
  • Patent number: 3946211
    Abstract: A filter is provided to substantially nullify the effect of process noise of less than a preset amplitude limit on the measurement of a process variable. The filter passes on to a controller or other device all signal changes greater than this amplitude. Within the amplitude limit the signal is damped by a first order lag with a filter time constant typically at least an order of magnitude greater than the average period of the noise to be filtered, but outside the amplitude limit, signal changes are passed immediately with no lag to a device such as a controller. The filter functions by generating a compensating signal essentially duplicating the process noise and then subtracting this compensating signal from the filter input signal, thus canceling this noise from the signal passed to the controller or other device. By subtracting only a limited value of this compensating signal from the filter input, changes of input greater than this limit are not compensated, and are thus immediately passed with no lag.
    Type: Grant
    Filed: July 17, 1974
    Date of Patent: March 23, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Theron W. Jenkins, Jr.
  • Patent number: 3941665
    Abstract: In the measurement of ion concentration, a selected base is added to the sample liquid which reduces the hydrogen ion content without producing other cations of a size to which the measuring electrode is sensitive. Bases having a high molecular weight and a dissociation constant, particularly secondary and tertiary amines are suitable for us. The system includes an absorber which mixes sample liquid with gaseous base, means for pressurizing the reference electrode, and an analyzer cell which prevents contamination of the measuring electrode with reference fluid leaking from the reference electrode. A separate reservoir mixes known concentration solutions for calibration purposes. The concentration readout meter of the system includes an auxiliary dial for ease of calibration.
    Type: Grant
    Filed: December 3, 1971
    Date of Patent: March 2, 1976
    Assignee: Leeds & Northrup Company
    Inventors: Edgar L. Eckfeldt, William E. Proctor, James U. Eynon
  • Patent number: 3939459
    Abstract: A digital signal linearizer for obtaining a linear digital output from a non-linear input. The output voltage of a thermocouple is converted to a train of pulses by a dual slope analog to digital converter. The number of pulses in the pulse train is proportional to the voltage and is linearized by a pulse rate multiplier programmed to vary over successive ranges of pulse counts corresponding to linear segments approximating the non-linear characteristic relating temperature and voltage. The linearized pulse train out of the multiplier is counted and displayed directly in temperature units.
    Type: Grant
    Filed: January 9, 1974
    Date of Patent: February 17, 1976
    Assignee: Leeds & Northrup Company
    Inventor: Howard S. Hoopes
  • Patent number: 3937615
    Abstract: An auto-ranging glucose measuring system including a device capable of mixing a glucose containing solution and a diluent in a variable ratio, a glucose oxidase enzyme converter column for converting the diluted glucose solution to hydrogen peroxide as one of the products, an amperometric detector for producing an analog electric signal proportional to the concentration of hydrogen peroxide, a high-low limit circuit for producing a pulse output when the analog electric signal is greater than the preset high limit of the linear span of the detector or is less than the preset low limit of the noise level of the detector, an electronic motor speed changing circuit interposed between a source of alternating current and a pump motor in said mixing device, having a frequency dividing network controllable by a register whose contents may be incremented or decremented by a pulse from the high-low limit circuit.
    Type: Grant
    Filed: December 17, 1974
    Date of Patent: February 10, 1976
    Assignee: Leeds & Northrup Company
    Inventors: Peter J. Clack, George R. Moreland