Showing papers on "Inductive sensor published in 1993"

Capacitive proximity sensors

Abstract: Capacitive proximity sensors (10) are disclosed that can be fabricated in different shapes, sizes and materials used in a wide variety of applications. Each such sensor includes a sensing electrode (11) and a guard electrode (12). The sensor electrode and guard electrode can be parallel conductors separated by an insulating layer (13), such as a double-sided circuit board shaped to suit the application. One such sensor is transparent for use in conjunction with an optical bar-code scanner. Another sensor is annular in shape for use in conjunction with a telephone transmitter. The sensing electrode and the guard electrode are driven in unison by an RF signal (21). The proximity of an object to the sensor is observed by detecting (in 24) changes in the RF current flowing through the sensing electrode caused by the proximity of an object to the sensing electrode.

Double-driven shield capacitive type proximity sensor

Abstract: A capacity type proximity sensor comprised of a capacitance type sensor, a capacitance type reference, and two independent and mutually opposing driven shields respectively adjacent the sensor and reference and which are coupled in an electrical bridge circuit configuration and driven by a single frequency crystal controlled oscillator. The bridge circuit additionally includes a pair of fixed electrical impedance elements which form adjacent arms of the bridge and which comprise either a pair of precision resistances or capacitors. Detection of bridge unbalance provides an indication of the mutual proximity between an object and the sensor. Drift compensation is also utilized to improve performance and thus increase sensor range and sensitivity.

Rotational speed control and use of same to control the rotational speed of an electric hand tool motor

Abstract: The process of controlling rotational speed of an electric motor of an electric hand tool, including providing an electric motor of an electric hand tool with a rotational speed control comprised of displacement means for providing displacement in response to manual operation of the electric hand tool selected from the group consisting essentially of a linear displacement device for providing linear displacement (s) and an actuating dial for providing arcuate displacement (S); an elastic membrane to which the displacement means is articulatedly connected so that during displacement of the displacement means the elastic membrane deforms as a function of the displacement; actuating means comprising a sensor element coupled to the elastic membrane so that the sensor element produces an electrical output variable as a function of the deformation of the elastic membrane, the sensor element being selected from the group consisting essentially of a Hall sensor, an inductive sensor, and a sensor switch; and an electronic switch for rotational speed control connected to the actuating means, from which it receives the electrical output variable, and to the electric motor of the electric hand tool; and manually operating the displacement means of the rotational speed control to control the rotational speed of the electric motor.

Inductive proximity sensor with periodic switching for sensing the presence of objects

Abstract: An inductive proximity sensor determines if a metallic object is in close proximity. An inductor is placed near the object. Several switches control the direction of the voltage passing through the inductor. During a first time period, the voltage flows through the inductor to induce a magnetic field in the object. During the second time period, the voltage is reversed in the inductor to quickly eliminate any current in the inductor. The decaying magnetic field in the object induces a voltage in the inductor which is measured during a third time period and compared to a reference value to determine the proximity of the object to the sensor.

Telecommunications instrument with capacitive controller

Abstract: of EP0564164Capacitive proximity sensors (10) are disclosed that can be fabricated in different shapes, sizes and materials used in a wide variety of applications. Each such sensor includes a sensing electrode (11) and a guard electrode (12). The sensor electrode and guard electrode can be parallel conductors separated by an insulating layer (13), such as a double-sided circuit board shaped to suit the application. One such sensor is transparent for use in conjunction with an optical bar-code scanner. Another sensor is annular in shape for use in conjunction with a telephone transmitter. The sensing electrode and the guard electrode are driven in unison by an RF signal (21). The proximity of an object to the sensor is observed by detecting (in 24) changes in the RF current flowing through the sensing electrode caused by the proximity of an object to the sensing electrode.

Magnetoresistive current sensor having high sensitivity

Abstract: The present inventors have discovered that a compact, highly sensitive current sensor can be made for any inductive component having an air gap in its magnetic path by disposing a layer of magnetoresistive material in the path of the fringing magnetic field. In the preferred embodiment, a thin magnetoresistive film of La w Ca x Mn y O z on a LaAlO 3 /Al 2 O 3 substrate provides a high sensitivity in the range of 1-100 mV/ampere of DC current in the inductive component. The current sensor consumes a very small amount of power and provides the desirable electrical isolation between the sensor and the active device circuit.

Evaluating method and circuit for an inductive sensor

Abstract: A method for evaluating an inductive sensor (1, 9), particularly a displacement sensor (1), is proposed, the set displacement (s) being determined from the measured inductance (L) of the sensor by means of a microcontroller (15). In this process, the temperature-dependent copper resistance (Ri) of the winding (2) of the displacement sensor (1) is determined by means of a measuring current which is constant in time. The microcontroller (15) is then used for temperature-compensating for the displacement (s) determined from the inductance (L) with the aid of a value corresponding to the copper resistance (Ri). The method can be used, in particular, in the case of displacement sensors which are employed in locations with highly fluctuating temperatures.

Vehicle detector with environmental adaptation

Abstract: A reference value used in a vehicle detector is checked and adjusted. The vehicle detector determines the speed of a vehicle which it has detected and then makes a sample measurement after the vehicle has left the detection area of its inductive sensor. The timing of the measurement is based on the speed of the vehicle. The sample measurement is compared to the reference value, and adjustment of the reference value is made accordingly. In order to identify the cause of changes in the sensor drive oscillator signal frequency, the frequency of the oscillator signal is measured while connected to a dummy sensor not affected by vehicles. The reference value also is adjusted to reflect slow changes (drift) in sensor drive oscillator frequency. To identify changes in sensor drive oscillator frequency caused by mechanical difficulties which require maintenance activity to correct, a rate of frequency change of the sensor drive oscillator signal is determined over the plurality of measurement scanning segments.

Integrated Non-Contact Molten Metal Level Sensor and Controller

Abstract: A metal casting control device is provided for use in conjunction with a semi-continuous metal casting system. The control device is an integral module containing a metal surface elevation sensing device, a valve actuator for positioning a metal distribution control valve, and electronic circuits associated with these mechanical components. The control device module is adapted to be connected to an overhead metal distribution launder by a single quick-coupling for convenient and simple removal and replacement. Calibration of the control device is performed after installation by mounting a calibration target on the metal casting system and vertically adjusting the metal surface elevation sensing device until an integral calibration indicator positioned on the control device indicates that the proper vertical position has been attained. The metal surface elevation sensing device is formed by a manually-adjustable sensor carriage and a sensor support which is mounted for automatic vertical movement relative to the sensor carriage. An inductive proximity sensor is supported over a metal casting station by the sensor support. The vertical position of the sensor support is controlled to maintain the sensor within a fixed vertical distance from the surface of molten metal within the metal casting station.

Detector for sensing magnetic piston position in cylinder - uses two magnetic sensors, one mother sensor acting as a distribution device for transfer of signals to computer

Abstract: Two sensors, e.g. reed contacts, Hall sensors or inductive sensors are mounted on the outer cylinder wall. The sensor signals are fed to a computer or relay via cables for evaluation. The supply lines (12) of a second sensor (14) are coupled to those (17) of a mother sensor (15) acting as a distribution component and as a sensor. The signal wire (13) of the second sensor is fed via the mother sensor and fed to the computer with the signal wire (18) of the mother sensor. USE/ADVANTAGE - For accurate position measurement in hydraulic or pneumatic cylinder. Reduced number of lines without endangering sensor function or increasing wire diameter.

Evaluation circuit for inductive sensor - includes coil with inductance dependent on measurement parameter, oscillator and synchronous rectifier, and allows separate measurement of coil's resistance and inductance

Abstract: The evaluation circuit contains at least one coil (14) with inductance dependent on the measurement parameter, an oscillator (10) with output signal fed to one input of the coil and a synchronous rectifier (20) to which the induced voltage is fed. The rectifier receives timing signals from the oscillator with phase related to the induced voltage phase so as to enable separate measurements of the resistance and inductance of the coil. A temperature compensation of the sensor signal is performed using the real part of the impedance of the coil. USE/ADVANTAGE - Esp. for an integrated displacement sensor or steering angle sensor. The circuit achieves very simple yet accurate temp. compensation without using an additional temp. sensor.

Radio controlled mist dispenser - has converter between receiver and output unit

Abstract: The radio-controlled dispenser, for a gas medium, has a converter (5) between the receiver (3) and the output to process the control signal and control the output unit. The converter (5) is either in close optical, acoustic proximity to the inductive or capacitative field of the receiver and coupled accordingly, or is connected through a loudspeaker or headphones at the receiver. The receiver is pref. a TV set. The control signal for a mist delivery is an image pattern on the screen (11), to be detected by a photo-unit (13) at the converter (5). The control signal can be overlaid on the TV acoustic signal, with an acoustic or inductive sensor at the loudspeaker for the converter (5). The control signal can also be an acoustic pulse series, outside the audio range, or detectable at max. 3m from the TV receiver (3). The converter (5) is mechanically secured to the TV receiver (3) by a release fitting. The output unit is a TV remote control, on an inhaler. USE/ADVANTAGE - The appts. is for the delivery of a fragrant mist, or for the dispensing of a medicated mist. For TV instruction of children with breathing problems, breathing practice with an inhalation can be remotely controlled to the TV receiver. The dispenser system can be fitted to conventional TV sets, and is compatible with their operation.

Longer-lasting inductive sensor with an electrical coil having improved load-bearing and thermal properties

Abstract: The inductive sensor has an electrical coil (14) having winding end portions (114) and current conductors (15) having conductor end portions (115) which are electrically contacted by the winding end portions (114) of the coil in a contact region (18) in the sensor housing (10). A permanently elastic material (26), advantageously silicone, encloses the contact region (18) between the conductor end portions (115) and the winding end portions (114). A temperature-resistant circumferential element (28) bearing on the housing (10) also encloses the contact region (18). This circumferential element (28) can be a polyimide strip or heat-resistant adhesive tape. This inductive sensor allows temperature fluctuation cycles to be increased by up to four times without damaging the coil wire and improves sensor durability.

Passenger conveyor missing step detection

Abstract: An inductive proximity sensor 26 is wider than a normal gap between moving escalator steps 10, 12 so that the inductive proximity sensor 26 is always in front of one step or another and provides a constant signal, when steps 10, 12 are passing the inductive proximity sensor 26, and stops the steps 18, 12, 14, 16 when the inductive proximity sensor 26 detects no steps.

Conductor bar for connecting coil of inductive sensor to electric feed

Abstract: An inductive sensor (11) with an electric coil (14) cooperates with a revolving, magnetically conducting part to produce electric signals. The ends of the windings of the coil (14) are wound on at one end (21) of a conductor bar (15). A securing bracket (31) is punched out of the conductor bar (15) so that the bent end (21) of the conductor bar can be fastened and the securing bracket (31) also presses on the bent end (21). In this way, the end (21) of the conductor bar is securely fastened and cannot be detached in particular during a change in temperature. This improves the durability of the sensor (11 ).

Inductive sensor for i.c. engine injection/ignition control - measures position or speed of notched wheel, operating in short circuit mode and terminated by resistance less than or equal to inductive impedance

Abstract: The inductive sensor (2) is provided as a current source for contactless measurement of the position or speed of a wheel (1) with peripheral notches. The sensor is formed as an inductance, operated in short circuit mode, which detects the alternating current fluctuations in the wheel as it passes the sensor. The inductance is terminated with a resistance less than or equal to the inductive impedance. The connections of the resistance or inductance are connected directly or via resistors to the inverting or non-inverting input of a differential amplifier. USE/ADVANTAGE - For controlling motor vehicle operating characteristics, e.g. for ignition, fuel injection, transmission, antilock brakes and antislip control. Achieves approximately constant signal level.

Evaluation circuit for an inductive sensor

Abstract: An evaluation circuit for an inductive sensor, particularly a displacement sensor is proposed This contains an inductance (L) dependent on the displacement to be measured The inductance (L) is a component of a Wheatstone bridge (R1, R2, R3, L) The inductance (L) is associated with a switch (S) The bridge voltage (UA) is monitored by a comparator (OP) A microprocessor (MC) detects the time (T) between the actuation of the switch (S) and the zero transition of the bridge voltage (UA) The time (T) is proportional to the value of the inductance (L) but independent of the value of the supply voltage (UE)

Engine timing plate

Abstract: An engine timing plate for cooperating with an engine driven timing wheel and an inductive sensor is provided. An arcuate plate is formed to fit internally within an ignition system housing. The plate includes at least two separate slots positioned on an arc such that the plate is movable, relative to two mounting screws of the housing, over a selected angular range for adjusting engine timing. A sensor mount is included for engaging the inductive sensor in a position adjacent to the timing wheel. An elongate window in the plate is positioned for exposing a timing line that is visible on a mounting surface of the housing. The window provides visual guidance with respect to the timing line in positioning the inductive sensor. The elongate window may provide a series of reference lines for more accurately aligning the plate through relative positioning of the timing line with the series of reference lines. As such, the inductive sensor may be readily positioned over the selected angular range along the outside arc of the timing wheel for modifying engine timing.

Probe tip lowering and setting system for film conductivity spreading resistance measurement on substrate - arranges probe, carrier and optical, inductive or capacitive path measuring unit on common force-exerting frame , which is fixed to linear drive.

Abstract: The measuring tip (1) is clamped in an adjustable carrier (2), which is connected with a displacement measuring unit (3). The measuring tip, the carrier and the displacement measuring unit are arranged at a common force exerting frame (5). The frame is connected rigidly with a positionally controllable linear drive (6). The carrier (2) is vertically movable and is clamped between two leaf springs (7). The springs are fixed to the common frame (5). The displacement measuring unit (3) can take the form of a capacitive sensor, an inductive sensor or an optical sensor. ADVANTAGE - Permits controlled lowering and application of tip for carrying out conductivity or potential measurements.

Electronic devices with sensors

Abstract: A sensor unit which comprises a sensor, and a detector for detecting an output from the sensor is attached removably to a device case with a display. Data on the basis of detection signals from the detector of the sensor unit is displayed on the display of the case. Thus, only a desired sensor can be provided in the case to thereby reduce the size and power consumption.

Method and apparatus for detecting weld junctions in steel sheets using an inductive sensor to detect thickness variations in the sheet

Abstract: Apparatus (40) locates welds or other junctures (20) in sheet material (12). The apparatus (40) includes a sensor (16) that produces a varying signal that is a function of the distance (100) between a surface (26) of sheet material (12) and the sensor (16), a differentiator circuit (42) differentiates the varying signal as a function of time, a comparator (44) compares the differentiated signal with a calculated allowable and sends a signal to an input (90) of an electronic latch (46), the electronic latch (46) sends a signal to a reject mechanism (48), and the reject mechanism (48) sends a reject-accomplished signal to a reset terminal (98) of the electronic latch (46). The method of the invention includes transporting the sheet material (12), producing a rate of change signal that is a function of changes in thickness (18) of the sheet material (12), determining an allowable rate of change signal, and comparing the produced rate of change signal with the allowable rate of change signal. Preferably, the producing step includes obtaining a varying electrical signal whose variations are a function of variations in the thickness (18) of the sheet material (12), and developing a rate of change of signal from the varying electrical signal.

Circuit for generating an rpm-dependent sequence of signals.

Abstract: Described is a circuit for generating an rpm-dependent sequence of signals, the circuit processing a potential-free output signal generated by an inductive sensor which monitors a moving part whose motion is rpm-dependent. The processing is carried out in such a way that hysteresis switching occurs according to the amplitude of the sensor signal. The circuit avoids so-called self-adjustment, has particularly low susceptibility to interference and has a low response threshold. It is possible, by means of an external capacitor, accessible from the outside, and an associated resistor, to adapt the hysteresis switching to meet requirements.

Method for the straightness measurement of vertical guideways of machine tools using capacitive and inductive sensors

Abstract: In this paper a new method for the straightness error measurement of vertical guideways of machine tools is presented. A taut wire which is hung near the vertical guideway is used as the datum line for measuring the vertical guideway. The capacitive and inductive sensors are fixed on the spindle box of the machine tool which can move up and down along vertical guideways. The difference between the spindle box and the taut wire measured by the capacitive sensor indicates the straightness error motion of the spindle box. The influence of the straightness of the taut wire can be eliminated by using reversal method. The relative error between the spindle box and the vertical guideway is measured by the inductive sensor. The straightness of the vertical guideway can be obtained by calculating the difference of the measured error motion and the relative error. The measurement error by this method in our measurement is less than 3 m.

Digital transducer system

Abstract: A variable reluctance transducer system incorporating digital control of parallel resonant circuits (L1C1, L2C1) including two inductive sensors (L1, L2) on each side of a flat diaphragm. The two parallel resonant circuits provide dual frequency signals for digital calculation to obtain a quotient of the frequencies, thereby substantially eliminating the resonant frequencies as a variable in the accuracy of the device. Manipulation of the produced quotient by a microcontroller (10) employing digital calibration tables stored in a programmable read only memory (14) allows calibration responsive to a temperature sensor (16), thereby substantially eliminating temperature induced error in the system.

Inductive sensors for distance measurement through a metallic screen: application to the primary control of a nuclear reactor

Abstract: This paper presents an interesting design of magnetic sensors applied to the distance measurement, through a metallic medium [1]. By a detailed physical analysis of this problem, an original modelling for predetermination and optimisation of the performances of this system is achieved, and successfully compared with experimental results. The interest of such a system is demonstrated through two major industrial applications, linked to the control of a pressurised water reactor with enriched uranium. In a first application, the sensor is used to detect the passage of magnetic slots, and provides some informations for incremental counting. This system gives reliable data on the position of the control rods moving up and down into the nuclear reactor. The other application uses the signals given by both elements of a twin sensor and a target with particular geometrical dimensions. A differential measurement between the two sensors gives an analog information on the lateral position of the target, an...

Schaltungsanordnung zur erzeugung einer drehzahlabhaengigen signalfolge

Abstract: Described is a circuit for generating an rpm-dependent sequence of signals, the circuit processing a potential-free output signal generated by an inductive sensor which monitors a moving part whose motion is rpm-dependent. The processing is carried out in such a way that hysteresis switching occurs according to the amplitude of the sensor signal. The circuit avoids so-called self-adjustment, has particularly low susceptibility to interference and has a low response threshold. It is possible, by means of an external capacitor, accessible from the outside, and an associated resistor, to adapt the hysteresis switching to meet requirements.

Inductive proximity sensor monitoring arrangement - has HF frequency generator divided into two oscillators, with evaluation of total current from DC source

Abstract: The arrangement monitors the functioning of inductive proximity sensors (2) by using a sensitive high-frequency generator, an evaluating unit which converts the degree of external influence, the approach of somebody or something, into useful signals, and a direct voltage supply for the HF generator and the evaluating unit. The HF generator is subdivided into at least two part oscillators (1a,1b) sensing in common and simultaneously. A self-monitoring process for faults or interference is effected by monitoring the current taken from a direct current source (3), constant in normal operation. USE/ADVANTAGE - Allows self-monitoring without additional circuitry.

Current control switching circuit with current decrease prediction

Abstract: A switching circuit for controlling the current in a load and accurately predicting its decrease by means of a galvanically isolated inductive sensor (12) providing the time derivative of the load current and followed by a capacitive integrator. An embodiment having two separate branches and an alternative, adaptive embodiment are disclosed. Applications mainly include current control circuits in power switching regulators, particularly of the high-frequency kind.

Busbar, in particular for an inductive sensor.

Abstract: An inductive sensor (11) with an electric coil (14) cooperates with a rotating, magnetoconductive part to emit electric signals. The ends of the windings of the coil (14) are wound on an end (21) of a busbar (15). In order to secure the bent end (21) of the busbar, a securing bracket (31) is punched out of the busbar (15) and pressed on the bent end (21). The end (21) of the busbar is thus reliably secured, so that it cannot become loose in particular because of temperature variations. The durability of the sensor (11) is thus improved.