Patents by Inventor Douglas G. Ritchie

Douglas G. Ritchie has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5176662
    Abstract: An improved subcutaneous injection set is disclosed which has a soft cannula for subcataneous delivery of a selected medication to a patient. The cannula is supported by and protrudes outwardly from a cylindrical support hub of a housing adapted to receive the selected medication. A flanged base end of the cannula is disposed within the housing and is captured by a swaged lock rim to retain a sealing gasket under compression against an annular seat within the support hub, thereby preventing leakage of the medication through the hub and about the exterior of the cannula.
    Type: Grant
    Filed: August 23, 1990
    Date of Patent: January 5, 1993
    Assignee: Minimed Technologies, Ltd.
    Inventors: Gerald Bartholomew, Douglas G. Ritchie
  • Patent number: 4237935
    Abstract: A body of electrically insulating material contains a passageway extending completely through the body. The passageway includes a flexible diaphragm dividing the passageway into two compartments to isolate a transducer placed on one side of the diaphragm from direct contact with fluid contained on the opposite side. A pressure relief port, passing from one side of the body to the passageway on the fluid side of the diaphragm, is covered with an "O" ring. Excessive fluid pressure forces the "O" ring away from the relief port to vent the pressure and thereby prevent damaging the transducer.
    Type: Grant
    Filed: December 14, 1978
    Date of Patent: December 9, 1980
    Assignee: Eaton Corporation
    Inventors: Julian Delmonte, M. Janet Kirkwood, Douglas G. Ritchie
  • Patent number: 4237900
    Abstract: An implantable body transducer having a self-contained calibration means. An exemplary embodiment comprises an implantable body pressure measuring transducer utilizing an L-C oscillator having a resonant circuit comprising a fixed L and a variable C, the variable C having a fixed capacitive electrode and a movable capacitive electrode in the form of a stiff pressure responsive diaphragm, the output frequency of the oscillator being a function of the pressure sensed by the diaphragm. The transducer incorporates a self-contained calibration means which contains predetermined calibration data with respect to the variable C. The predetermined calibration data is stored in a plurality of PROM storage elements which are sequentially addressed in accordance with the output of a counter, the PROM storage elements providing a serial bit stream which can be used to pulse-code modulate the L-C resonant circuit output.
    Type: Grant
    Filed: February 14, 1979
    Date of Patent: December 9, 1980
    Assignee: Pacesetter Systems, Inc.
    Inventors: Joseph H. Schulman, Douglas G. Ritchie