Abstract: A capacitive sensor system including a sensor with two fixed plate elements having opposed planar, electrically conductive surfaces serving as electrodes. The sensor further includes a movable, electrically conductive diaphragm positioned between the electrodes. At least one diode detector network is coupled across the electrodes. The diode detector networks each include a pair of oppositely directed series connected diodes with the junction between the diodes of each network being coupled to the diaphragm. In embodiments having only one diode detector network, the junction between the two diodes may be directly or capacitively coupled to the diaphragm.
Abstract: Mechanical linkage comprising two pairs of flexure elements constrains the motion of a reference member to be along a reference axis even in the presence of applied moments. The linkage includes a pair of V-shaped flexure elements coupled at their vertex ends to the reference member at points along the reference axis. One of these flexure elements is coupled at its distal ends to a support member fixed with respect to the reference axis. The other of the V-shaped flexure elements is coupled at its distal ends to one of a pair of elongated flexure elements at a point between its two ends. The pair of elongated flexure elements are affixed at one end to the support member and at their other end are adjustably coupled to the support member. This arrangement permits "fine tuning" of the reference axis so that the linkage exhibits the desired high resistance to moments applied to the reference member.
Abstract: A weighing system includes a weighing pan connected to a rigid armature by a linkage in a manner constraining the armature to motion along a reference axis with respect to the housing. Another linkage couples the armature to a housing. A low friction damper is coupled between the weighing pan and the housing to damp the relative motion of the force input member and the housing. A force transducer, comprising a pair of complimentary opposed surfaces having a mutual separation which is related to the force across the transducer, is coupled between the armature and the housing. Coupled to the transducer is a position sensor which generates a signal representative of the separation between the complimentary opposed surfaces of the transducer.
Abstract: A capacitive pressure sensor including a concave base member coupled to a central base support. The base member has a flange extending from its rim having a substantially planar surface. A conductive, deformable diaphragm is stretched across the flange and held by a clamping ring having a surface complementary to the flange. A substantially planar electrode is positioned substantially parallel to and displaced by a predetermined distance from the diaphragm by an electrode support member coupled to the central base support.
Abstract: A system for generating a signal linearly related to the capacitive reactance of a sensor capacitor. The system includes an oscillator for providing an oscillatory signal characterized by a peak-to-peak voltage proportional to an applied control signal, at least one capacitive network and associated peak detecting network, and a feedback network. The capacitive network includes a drive capacitor and a sensor capacitor connected in series between the oscillator and a reference potential, and the peak detector includes means to generate a peak signal representative of the peak-to-peak voltage at the junction between its associated coupling and sensor capacitor. The feedback network produces the control signal for the oscillator whereby the peak amplitude of the voltage across the drive capacitor is constant.
Abstract: A pressure sensing device and method of construction therefor. The device includes at least two dielectric discs which are fused together at their peripheral boundary to form a hollow monolithic capsule having two nominally planar opposed inner surfaces. The opposed inner surfaces of the capsule are mutually separated by a uniform gap near the peripheral boundary and by a distance related to the difference in pressure interior and exterior to the capsule otherwise. Conductive films are disposed on opposed portions of the inner surfaces of the capsule. The device further includes a means for electrically coupling each of the conductive films to an associated terminal exterior to the capsule. The capacitance between these terminals is related to the above-mentioned pressure differential.
Abstract: A system for generating a signal which is a predetermined function of the capacitance of a sensor capacitor. The system comprises a sensing network including two series capacitors, at least one being the sensor capacitor. The system further comprises a switching network, and a feedback network coupled to the sensing and switching networks. The feedback network generates a feedback signal representative of the difference in charge stored on the series capacitors from a predetermined value. The switching network cyclically interconnects the feedback and sensor networks with the feedback signal and externally applied reference potentials whereby the average charge stored on the series capacitors over each cycle is substantially equal to the predetermined value. In some embodiments, the feedback signal is a linear function of the reciprocal of capacitance of the sensor capacitor.
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