Abstract: A hydraulic accumulator including a fluid chamber and a displaceable piston that is connected to a piston position-measuring means is disclosed. Embodiments of the hydraulic accumulator can provide a device that measures the available fluid volume in the accumulator. In embodiments, the displaceable part of the piston may separate fluid volume from gas volume, and may be connected to a wire that runs through the fluid volume and exits the outside of the accumulator through a sealed opening. Further, in embodiments, the wire may be led over pulleys and through a hollow member connected to the accumulator. The position of an associated metallic core member can be electrically monitored to provide position and fluid volume information.

Abstract: A single housing with a non-ferromagnetic piezo-driven flexure has primary and secondary coil forms of different diameters, one coaxially inside the other, integrated in the flexure. The cylinders defining the planes of the primary and secondaries do not spatially overlap. The secondary coil forms may be wound in opposite directions and wired to provide a transformer device. Movement of the primary relative to the secondaries in the direction of the central axis of the coils can be differentially detected with high precision.

Abstract: Techniques for coupling with devices that convert displacements into differential voltages and improve the sensitivity of such devices. The disclosed system improves the accuracy and resolution of a transducers such as an LVDT by converting certain parts of the circuit to a digital circuit. One embodiment uses a processor, although other digital processing circuitry may also be used.

Abstract: The invention relates to position sensors of the linearly variable induction difference type. When cost constraints prevent the use of transformers with guaranteed phase-shift tolerance to achieve an accuracy objective, it is advantageous to provide an independent demodulation of the signals of the two windings. The error signal thus has a lower dependence on the phase shift and the accuracy is typically enhanced by a factor greater than an order of magnitude.

Abstract: A position sensor has a moving coil part that is formed from a first coil form formed of a non ferromagnetic material, and a second coil that also has its form made of non-ferromagnetic material. The coil forms can be formed of non ferromagnetic adhesive. One of the coils moves relative to the other. The stationary coil part sufficiently close to said moving coil part such that magnetic flux from said moving coil part is induced into said stationary coil part. A primary coil is driven with a voltage. The operation senses voltages induced into a plurality of secondary coils, from movement of the primary coil relative to the secondary coils. The sensing can be done using a differential amplifier.

Abstract: A linear variable differential transformer (LVDT) system is disclosed. The system has an LVDT. A signal conditioner circuit is coupled to the LVDT. The signal conditioner circuit uses an inductance of the LVDT primary as a micro-power excitation carrier frequency to lower a drive power of the system. The signal conditioner circuit generates output currents that are summed and filtered to generate a position proportional voltage.

Abstract: A force detecting element is used to move a moving coil that is formed without ferromagnetic materials and is driven using a stationary coil that is formed without ferromagnetic materials, thereby producing an output signal which is more linear than the previous techniques. The output signal produces an output indicative of a resolution in the range of microns or less.

Abstract: A position sensor comprising a primary winding (26) for generating a magnetic flux, a first secondary winding (24.1) the number of turns of which increases in one direction, a second secondary winding (24.2) the number of turns of which increases in the opposite direction to that of the first secondary winding. Both secondary windings (24.1, 24.2) are subjected to the magnetic flux generated by the primary winding (26) whereby voltages are induced in the secondary windings. The sensor further comprises an element movable with respect to the secondary windings. The element is of a magnetic or conductive material and distorts, in its vicinity, the magnetic flux generated by the primary winding (26). By providing third and fourth secondary windings at right angles to the first and secondary windings it is possible to detect position in two dimensions.

Abstract: A linear variable transformer (LVDT) for use in a transducer. The LVDT has a non-ferromagnetic core which may eliminate Barkhausen noise and thereby improve the sensitivity of the resulting measurements. In one aspect, this system may be used in an atomic force microscope.

Abstract: A linear variable differential transformer (LVDT) is disclosed that has first and second coil is formed of materials that minimize the Barkhausen noise, and hence which produces outputs that are substantially independent of any Barkhausen noise. In an embodiment, the Barkhausen independence is formed by making the coils of non-ferromagnetic materials. For example, other materials could be used that have a material as the core that does not include grain boundaries or does not include metastable magnetic.

Abstract: A linear variable transformer, or LVDT, for use with the transducer, which has a non-ferromagnetic core that can eliminate Barkhausen noise. By eliminating the Barkhausen noise, the sensitivity of the resulting measurements can be improved. The LVDT is formed of multiple coil assemblies which are moved relative to one another, and by using a non-ferromagnetic material, are capable of obtaining 1 ? resolution or better. Circuitry for obtaining a synchronous output is described, allowing a differential amplifier to synchronize one signal to another.

Abstract: In a circuit arrangement having a linear variable differential transformer as a displacement sensor or force sensor, having a selection circuit which is connected to the primary coil of the transformer and which provides an output current for triggering the primary coil, and having an analysis circuit which is connected to the secondary coils of the transformer and which provides a message signal, a control circuit used for triggering the selection circuit and the analysis circuit and for processing the measurement signal provided by the analysis circuit is connected to the primary coil in order to calculate the temperature of the circuit arrangement, and is configured such that it determines the temperature-dependent ohmic resistance of the primary coil and calculates from it the temperature and corrects accordingly the measurement signal provided by the analysis circuit.

Abstract: A linear variable transformer (LVDT) for use in a transducer. The LVDT has a non-ferromagnetic core which may eliminate Barkhausen noise and thereby improve the sensitivity of the resulting measurements. In one aspect, this system may be used in an atomic force microscope.

Abstract: A rotary input for a linear variable differential transformer (LVDT) system connects to a gear reduction system. The gear reduction produces a reduced rotary output in a rotary output member. The output member is threaded, and a nut is threaded onto the output member. Therefore, the nut translates as the rotary output member rotates. The armatures of one or more LVDTs attach to the nut. Each armature contains a magnetic member. As the nut translates along the threaded output member, the nut translates the armatures. Armature movement moves the magnetic members to create a differential voltage between the secondary coils of the LVDT.

Abstract: The purpose of the present invention is to reduce power consumption caused by controlling circuit in transmitting/receiving process between tablet system and cord less-battery less pointer apparatus. The present invention provides multi-channel switches set produced in semi-conductor process to replace traditional analog switch and tri-state element used in prior art as signal transmitting/receiving selector of inductive loops of tablet, which can simplify controlling circuit, enhance power efficiency of signal transmitting/receiving between tablet system and cord less and cell less pointer apparatus, and increase speed of response of signal transmitting/receiving between tablet and cord less-battery less pointer apparatus.

Abstract: Analog circuitry is disclosed for conditioning a signal from linear and rotary variable differential transformers having a primary winding, a pair of secondary windings and a movable core. The circuitry includes a unique closed loop negative feedback mechanism which, over time, adjusts the frequency of a voltage controlled oscillator so that a steady-state condition is achieved within the circuitry, whereby the total integrated value of the secondary winding voltages at an integrator remains equal to a reference voltage, thereby reducing the computational burden associated with solving an equation to determine the position of the movable core of the transformer.

Abstract: A circuit for a displacement detector having a contact sensor with a sensor coil forming a differential transformer is disclosed. The circuit includes a driver for generating a driving signal for driving the sensor coil, a standard signal processor for processing the driving signal and outputting a standard signal, an output signal processor for processing signals outputted from the differential transformer, a differential amplifier for carrying out differential amplification of the standard signal and the output signal from the output signal processing means, and an amplitude adjustor for adjusting the amplitude of the driving signal for the sensor coil to a constant value by feeding back the standard signal to the driver.

Abstract: A displacement detector has a contact sensor incorporating a differential transformer and a circuit for adjusting the amplitude of the driving signal for driving a differential transformer of the sensor by feeding back as a standard signal the driving signal through an amplifier and an AC-DC converter as a standard signal. The sensor has a housing containing a mobile member. The mobile member has a shaft with a hole. An outer tubular body of a linear bush and a ball guide each have a hole, and a pin is inserted through these holes movably in the direction of movement of the mobile member such that the rotation of the mobile member is prevented.

Abstract: A method for forming a non-contact position sensor having a predetermined stroke length comprises providing a pair of coil assemblies each comprising a primary and secondary coil of a predetermined size; providing a core member of varying magnetic density about its length; and inserting the core member within the coil assemblies, whereby axial movement of the core member relative to the coil assemblies causes a corresponding output signal from the coil assemblies indicative of the position of the core member.

Abstract: A transducer that reduces noise, increases sensitivity, and improves the time response of a linear variable differential transformer (LVDT). The device replaces the primary coil and the high permeability ferromagnetic core of conventional LVDTs with a primary wound around a moving non-ferromagnetic core. In addition to reducing or eliminating Barkhausen noise, this approach reduced or eliminated a number of other undesirable effects in conventional LVDTs including excessive eddy current heating in the core, non-linearities associated with high permeability materials and the length scale of the flux circuit. These improvements are coupled with improved LVDT signal conditioning circuitry. The device is also an actuator and may be used to convert differential voltages into force.

Abstract: Techniques for coupling with devices that convert displacements into differential voltages and improve the sensitivity of such devices. The disclosed system improves the accuracy and resolution of a transducers such as an LVDT by converting certain parts of the circuit to a digital circuit. One embodiment uses a processor, although other digital processing circuitry may also be used.

Abstract: A linear variable differential transformer (LVDT) assembly comprises a housing. A tube extends into the housing. An armature mounts inside of the tube and can move longitudinally within the tube. A coil assembly, which includes a primary coil and two secondary coils mounts on the outside of the tube. The coil assembly has adjustable connection with the housing. Consequently, the coil assembly can be adjusted longitudinally with respect to the armature until the LVDT is in the null position. That occurs when the differential voltage from alternating current through the secondary coils is zero.

Abstract: A rotary position transducer with a cosine and sine attenuating voltage wave output has the substantially linear portions segmented and pieced together from a predetermined set of conditions to form a continuously linearly varying voltage output.

Abstract: Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(&ohgr;t±d+&thgr;), sin(&ohgr;t±d−&thgr;)) are electrically synthesized which have electric phase angles (&thgr;) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. “±d” here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change.

Abstract: The present invention is intended to provide a ultra-precision high sensitivity displacement measuring device which has such a high resolution as to be able to make submicron measurement.

Abstract: A system for sensing the position of a vehicle foot pedal (1), comprises a non-contact sensor (8) associated with a displaceable element (2, 7) of the pedal (1).