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    Pressure compensation of membranetype sensors
    2.
    发明授权
    Pressure compensation of membranetype sensors 失效
    膜传感器的压力补偿

    公开(公告)号：US3663409A

    公开(公告)日：1972-05-16

    申请号：US3663409D

    申请日：1970-05-14

    Applicant: BECKMAN INSTRUMENTS INC

    Inventor： GREENE MALBONE W

    IPC: G01N27/49 ,  G01N27/30

    CPC classification number: G01N27/404

    Abstract: In a sensor for measuring the quantity of a substance in a compositionof matter of the type including a membrane which is permeable to the substance and substantially impermeable to liquid and ions, the permeability of the membrane being a function of the pressure thereon, the sensor providing an electrical output signal which is a function of the quantity of the substance in the composition of matter, there is disclosed an improvement consisting of a method and means for accurately compensating the output of the sensor for the effect of pressure upon membrane permeability by multiplying the output signal by the function ekp thus cancelling the pressure effect which is given by the function Poe-kp where Po=membrane permeability at zero pressure, p=absolute pressure, and k=a membrane constant. According to a preferred embodiment of the invention, such multiplication is achieved through the use of a pressure-driven, variable resistance in the feed-back loop of an operational amplifier.

    Paramagnetic gas sensor having capacitive position sensing and ac null balancing feedback
    6.
    发明授权
    Paramagnetic gas sensor having capacitive position sensing and ac null balancing feedback 失效
    具有电容位置传感和AC空余平衡反馈的参考气体传感器

    公开(公告)号：US3612991A

    公开(公告)日：1971-10-12

    申请号：US3612991D

    申请日：1969-10-24

    Applicant: BECKMAN INSTRUMENTS INC

    Inventor： GREENE MALBONE W

    IPC: G01N27/74 ,  G01R33/12 ,  G01R17/06

    CPC classification number: G01N27/74

    Abstract: Apparatus for determining the partial pressure of a paramagnetic gas in a gas mixture wherein a pivotally mounted test body is supported in an inhomogeneous magnetic field, the test body being deflected from a null position when the paramagnetic gas is present, the improvement wherein an AC bridge circuit is utilized, in response to deflection of the test body from the null position, to generate an AC signal indicative of the partial pressure of the paramagnetic gas. The bridge circuit comprises a pair of electrostatic vanes which, in conjunction with the test body, form capacitive elements of the bridge circuit. The AC signal is either measured to determine the test body position, or demodulated to provide a DC signal. The DC signal may be fed back to the bridge circuit to return the test body to the null position for improved linearity and stability. Apparatus is further provided to vary the fraction of the DC signal fed back to the bridge circuit with changes in temperature of the test body to compensate the apparatus for temperature variations.

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