Abstract: A method for analyzing a dielectric medium comprises the step of measuring, at one or more frequencies, the capacitance between a pair of electrodes immersed in the dielectric medium. The proportion of the or each capacitance measurement due to electrode polarization capacitance and/or to the residual capacitance of the dielectric medium is then determined using capacitance measurements made between the electrodes at a first frequency and at a second frequency, the ratio of the respective polarization capacitances at these two frequencies being predetermined. An apparatus for performing the method is also disclosed.

Abstract: The invention pertains to a method for controlling a transducer device (7) featuring supply lines (17, 18) in a level sensor. The transducer device (7) is coupled to a fork resonator with fork tines and is used for both oscillation excitation and also for oscillation detection. For detection of a defective transducer device or an incorrectly connected connection of this transducer device (7), the capacitance value between the supply lines (17, 18) or a variable proportional to this value is determined during the oscillation excitation and if there is deviation from a predetermined desired value by a predetermined amount, a fault signal is generated.

Abstract: A poppet valve moves up and down in a valve operating mechanism in an internal combustion engine. A cylindrical fixed electrode is fixed to a support plate on a cylinder head, and a cylindrical moving electrode is mounted to the lower surface of a valve spring retainer which is mounted to the poppet valve via a cotter. The fixed electrode is connected to a circuit which comprises a variable condenser and a resistance. The valve moves up and down during firing operation of the engine. Thus, variation in electrostatic capacity is detected by the two electrodes, transmitted to a circuit via a lead mounted to the fixed electrode, and converted to a voltage by the circuit, thereby detecting valve position exactly.

Abstract: A poppet valve moves up and down in a valve operating mechanism in an internal combustion engine. A fixed electrode is supported on a cylinder head, and a moving electrode is carried by the poppet valve. The fixed electrode is connected to a circuit, which together comprises a variable condenser and a resistance. The valve moves up and down during firing operation of the engine. Variation in electrostatic capacitance is detected by means of the two electrodes, transmitted to the circuit via a lead and a ground connection, and converted to a voltage by the circuit, thereby enabling detecting valve position more exactly.

Abstract: Method and apparatus for measuring distance includes a capacitance probe positioned adjacent a rotating member and within the housing of the rotating member such that the distance between the probe and rotating member can be measured. The rotating member and probe co-operate with each other so as to define a capacitor. An oscillator comprising a transmission line is electrically connected to the probe, the resonat frequency value of which is a function of the capacitance of the capacitor. The change in distance between the rotating member and the probe can therefore be measured.

Abstract: A capacitor test apparatus for checking the capacitance of a capacitor without removing the capacitor from the circuit. Selection of the designated capacitance of the capacitor by means of a user-actuated selector switch automatically selects a test signal frequency such that the reactance of the capacitor matches a reference impedance. A indicator circuit compares the actual reactance with the reference impedance to indicate the deviation of the test capacitor from its designated capacitance. The test signal is a low level sine wave which does not exceed the conduction threshold of semiconductor junctions associated with the capacitor. A user-actuated switch is provided for discharging any charge present on the capacitor prior to testing.

Abstract: Between a reference voltage point and the emitter or the source of a transistor of which the collector or the drain is connected to a power source and to which an signal is input at its base or its gate, DC current passing means for causing a current to flow from the emitter or the source to the reference voltage point and a capacitor connected to the reference voltage point at one end and charged with a voltage generated in the DC current passing means are provided. A detection output for the signal is obtained from the emitter or the source of the transistor, or the other end of the capacitor.

Abstract: A measuring system measures forces, deformations, and movements. The measuring system comprises at least one LC-circuit, at least one power supply for generating a voltage and a current in the LC-circuits, whereby the frequency, the amplitude, and the phase difference between the current and the voltage in a default situation are known and are furthermore a function of the variable to be measured, as well as at least one detection unit for detecting the frequency and/or the phase difference and/or the amplitude in the LC-circuit. The invention provides therewith a compact, simple and multifunctional measuring system by means of which a reading of the measured value is possible without contact with the subject.

Abstract: A self-excited microelectromechanical device is described. The device includes a resonating structure, such as a cantilever, which responds to a physical phenomenon by generating an induced variable frequency voltage signal corresponding to the physical phenomenon. Self-excitation circuitry connected to the cantilever processes the induced variable frequency voltage signal and produces a variable frequency voltage signal in a resonant pass band of interest that is applied to the cantilever to augment the effect of the physical phenomenon on the cantilever. An exemplary use of the device is as a power meter. In this context, the cantilever responds to the electric field associated with a power signal on a metered line. The cantilever transforms the voltage signal of the electric field into a corresponding frequency signal. The noise-immune frequency signal can be readily processed to reconstruct the power signals carried by the power line.

Abstract: A self-excited microelectromechanical device is described. The device includes a resonating structure, such as a cantilever, which responds to a physical phenomenon by generating an induced variable frequency voltage signal corresponding to the physical phenomenon. Self-excitation circuitry connected to the cantilever processes the induced variable frequency voltage signal and produces a variable frequency voltage signal in a resonant pass band of interest that is applied to the cantilever to augment the effect of the physical phenomenon on the cantilever. An exemplary use of the device is as a power line sensor. In this context, the cantilever responds to the electric field associated with a power signal on a power line. The cantilever transforms the voltage signal of the electric field into a corresponding frequency signal. The noise-immune frequency signal can be readily transmitted and processed to reconstruct the power signals carried by the power line.

Abstract: A tubular single-layer winding coil is installed on the outer periphery of a thin wall portion of a cylindrical container case and a columnar electrode is provided at the center of the inside of the cylindrical container case. A fuel channel is formed between the coil and the electrode so that the permittivity of fuel flowing through the fuel channel is detected from the electrostatic capacity therebetween. Further, variation of the electrostatic capacity due to the temperature characteristics of the fuel is compensated by the temperature characteristics of the permittivity of the thin wall portion of the sensor unit. Furthermore, variation of the electrostatic capacity due to the temperature characteristics of the fuel is compensated by the temperature compensation capacitor which is connected with the single layer winding coil in parallel.

Abstract: A tubular single-layer winding coil is installed on the outer periphery of a thin wall portion of a cylindrical container case and a columnar electrode is provided at the center of the inside of the cylindrical container case. A fuel channel is formed between the coil and the electrode so that the permittivity of fuel flowing through the fuel channel is detected from the electrostatic capacity therebetween. Further, variation of the electrostatic capacity due to the temperature characteristics of the fuel is compensated by the temperature characteristics of the permittivity of the thin wall portion of the sensor unit. Furthermore, variation of the electrostatic capacity due to the temperature characteristics of the fuel is compensated by the temperature compensation capacitor which is connected with the single layer winding coil in parallel.

Abstract: Apparatus for inspecting non-round annular containers includes elongated capacitive sensors, cooperating oscillators, which convert the sensor signal to a voltage corresponding thereto, and an electronic processor which receives the voltage and determines thickness. A displaceable electromechanical member is operatively associated with the sensor and emits an electrical signal corresponding to the degree of displacement of the sensor by a container being inspected. The electronic processor corrects the thickness determination by an adjustment of container diameter at the specific location where thickness is being monitored in order to compensate for container diameter variations due to the non-round characteristic of the container. In a preferred embodiment, linkage members secured to the rear of the sensor at a plurality of locations cooperate with a single displaceable element which converts the mechanical displacement of the sensor into a corresponding electrical signal.

Abstract: A device for detecting attempts at fraud by connection of an electric feed line (13) to an apparatus for reading and writing on a chip card (3) essentially comprises a resonance unit (6) coupled to a contacting element (2) of the apparatus, and a measuring device (7). In the resonance unit (6) a generator (4) which is coupled to a resonator (1) by way of an impedance converter (5) generates a standing wave. The feed line (13) disturbs the properties of the resonator (1), that being detected by the measuring device (7) and evaluated.

Abstract: A dielectric constant detecting apparatus comprises an LC circuit for shifting the phase of a high frequency voltage signal according to the dielectric constant of a liquid which passes between the coil and the electrode of the LC circuit. A resistor is connected between the LC circuit and at least one part of a phase comparator. The phase comparator detects the phase shift between high frequency signals provided at both ends of the resistor. The resistor and at least one part of the phase comparator are integrally included in an insulator. The output of the phase comparator is compared with a predetermined phase shift value. A voltage control device adjusts the high frequency voltage signal from the voltage applying device so that the phase shift detected by the phase comparator is further adjusted toward the predetermined phase shift value.

Abstract: An apparatus for detecting the concentration of alcohol mixed with gasoline or light oil comprises a dielectric constant detection device for providing a resonance frequency corresponding to the dielectric constant of the mixed fuel; a device for detecting the resonance frequency provided by the dielectric constant detection device so as to output a first frequency signal having the same frequency as the resonance frequency; a frequency divider which divides the first frequency signal by a variable factor; a fuel temperature detector which outputs a second frequency signal representing the detected temperature; and a dividing factor decision device for determining the frequency dividing factor based on the first and second frequency signals. The alcohol concentration is determined by the output frequency of the frequency divider.

Abstract: An apparatus for detecting an alcohol content of a liquid with high accuracy regardless of variance in a resonance frequency of a parallel resonance circuit constituted by inductance of a coil, capacity presented by a fluid within a liquid passage of a sensor unit and others. High-frequency voltage signals appearing at both ends of a resistor of a detector circuit connected in series to the coil are compared in respect to phase by a phase comparator, wherein difference signal resulting from the comparison is supplied to a voltage-controlled oscillator through a comparison integrator, the oscillation signal S.sub.vco of the oscillator being supplied to one end of the resistor through an amplifier. Through this phase synchronization loop, the oscillation frequency of the oscillator is forced to coincide with the resonance frequency, whereby a signal S.sub.out having a frequency bearing one-to-one correspondence to the resonance frequency is obtained from a frequency divider.

Abstract: In a fuel dielectric constant detecting apparatus, a high frequency signal is applied to an element for subjecting the high frequency voltage signal to resonance corresponding to the dielectric constant of the fuel. A DC voltage is applied to the subjecting element so that the duty of the high frequency signal be 50%, and the high frequency signals are so controlled that the phase shift between the signals provided at both ends of the resistor be a predetermined value. Alternatively, in the apparatus, the high frequency signal applying member includes a high frequency signal applying section and a reference high frequency signal applying section.

Abstract: Disclosed is a method of detecting a variation in stray capacitance by use of a PLL circuit.

Abstract: Apparatus for detecting thickness which includes an electrode detecting unit including a ground electrode and a detecting electrode. The electrodes oppose each other along a paper path. An oscillating circuit provides an oscillation frequency signal. A resonant circuit, having a resonator independent of the oscillating circuit, has a resonance point which changes in accordance with a change in electro-static capacitance corresponding to a change in paper thickness detected by the electrode detecting unit. A resonant circuit outputs a detection signal corresponding to the change in resonance point. By analyzing this detecting signal, a state of two sheets of paper passing through the path is detected as a change in paper thickness.

Abstract: The electrostatic capacitance sensing circuit comprises a resonance circuit composed of an electrode capacitance formed by a substance to be measured and sandwiched between two opposing electrode plates and an inductance at least part of which is connected in parallel to the electrode capacitance; an active element (e.g. transistor) for constituting an oscillator in cooperation with the resonance circuit; and in particular a capacitor connected between the resonance circuit and the active element. Since a dc bias voltage of the active element is substantially not applied to the electrode plates, it is possible to prevent electrolytic corrosion of the electrode plates due to electromotive force generated between the electrode plates when ions are resolved into the substance to be measured and therefore the substance changes to an electrolytic solution.

Abstract: Monitoring of the average dielectric constant in an extended volume of a medium such as soil is achieved using an oscillator incorporating a transmission line to be embedded in the medium. The transmission line is connected as the feedback loop of an amplifier, for one-way propagation of an electrical signal with a delay determined largely by the dielectric properties of the medium, such as its moisture content. The oscillation frequency is indicative of the dielectric constant of the medium.

Abstract: Disclosed is a multi-channel electrostatic sensor apparatus including a main oscillation circuit; a plurality of pull-in type sub-oscillation circuits which are adapted to synchronize with the main oscillation circuit to generate sub-frequency signals whose frequency is equal to the main oscillation frequency or a multiple thereof; and a plurality of resonance circuits which are sensitive to any change in exterior capacitance when detected by an associated detector for changing its resonator resonance point with respect to the sub-frequency signal. Positive synchronization of the sub-oscillation circuits with the single main oscillation circuit prevents any adverse effect from being caused by the varying stray capacitance in flexible conductors connecting the sub-oscillation circuits to the main oscillation circuit while allowing the relatively free movement of the video heads of a video system, on which video heads the sub-oscillation circuits and subsequent components are attached.

Abstract: An oscillator for use in a fluid detection apparatus for determining the respective percentages of first and second liquids in a mixture disposed within a chamber, including an inductive element immersed in the mixture such that the mixture at least partially determines a value of distributed capacitance exhibited by the element when energized; where the inductive element is a coil acting as a resonant element in an oscillator, and where the oscillator is of the tuned input type such that the coil and its distributed capacitance define a parallel resonant tank circuit which generates an oscillating signal at a resonant frequency of the tank circuit, the resonant frequency being inversely proportional related to the distributed capacitance of the coil.

Abstract: A capacitive difference sensor includes two sensor electrodes, each of which lies opposite a transmitting electrode fed by an electrical AC voltage source. A circuit arrangment connected to the two sensor electrodes for signal recovery generates a differential signal which corresponds to the difference between the displacement currents induced in the two sensor electrodes. The circuit arrangement includes a series resonance circuit comprising a coil and a capacitor, the resonance frequency of the series resonance circuit corresponding to the frequency of the AC voltage source. The two sensor electrodes are coupled via a transformer in opposite senses to the series resonance circuit and the differential signal is tapped off at the tap of the series resistance circuit formed by the connecting point between the coil and the capacitor.

Abstract: A device for measuring the resistivity of a conductive layer buried beneath an outer layer. The device is capacitively coupled to the buried layer by a driven electrode and a pickup electrode. An adjustable frequency source resonates the two electrodes with an inductor so that an attached meter measures the resistivity of only the buried layer.