Abstract: An angular position sensor for determining the relative angular position of two relatively rotatable ferromagnetic coaxial components, such as a rotor and stator. The components have the same number of regularly distributed teeth and the teeth in one component are separated by an air gap from the teeth in the other component. A plurality of coils are connected in series with each other and are disposed around the teeth in one of the components and correspond in number to the number of associated teeth. An electric excitation signal having a measurable constant electrical characteristic is fed to the plurality of coils from a source. The characteristic is modulatable in response to variations in the magnetic reluctance of the air gap effected by changes in the relative angular position between the two components. Electronic circuitry is connected to coils for measuring the modulation of the characteristics to determine the relative angular position of the components.

Abstract: In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

Abstract: In construction of a peripheral-magnetization type magnetic encoder having a rotary spindle and a magnetic head, a resin housing is formed by insert moulding so as to embrace the spindle leaving a slight tubular clearance to allow free axial rotation of the spindle, thereby providing direct, simple and stable support to the rotary spindle for enhanced precision in direction.

Abstract: Disclosed is here a rotary encoder having a recording medium including positional information arranged in a circumferential direction, sensors disposed opposing the positional information, and a driving shaft linked with a central position of the recording medium for detecting, based on a change in outputs from the sensors, the positional information of the recording medium rotated by means of the driving shaft. A link body is formed by achieving a bending work on an elastic plate such that bent lines of the elastic plate form a rectangular shape and that there are formed two pairs of opposing bent leg pieces, one of the two pairs of the opposing bent leg pieces is fixedly secured on the recording medium and the other one thereof is fixedly secured on a coupling body disposed in the proximity of the recording medium, and the driving shaft is inserted into and fixed on a shaft inserting hole formed in the coupling body.

Abstract: An interactive multiaxis encoder positioning system is provided for positioning a tool or a work piece to a degree of accuracy which is only limited by the encoder system and not the mechanical guides, slides and bearings of prior art systems. A highly precise and accurate multiaxis scale comprising a plurality of sets of grading indicia is made under accurate manufacturing conditions. The multiaxis scale is attached to a fixed or a moving part of the machine or apparatus and is positioned juxtaposed encoder means to provide relative movement to the grating scale means. Thus, the accuracy of positioning a tool or work holder is determined by the accuracy of the encoder and not by the accuracy of the mechanical positioning guides, slides and bearings.

Abstract: A rod member provided with magnetic and non-magnetic portion arranged alternatingly is provided and a plurality of detecting heads for detecting magnetic resistance are disposed along the longitudinal direction of the rod member with predetermined distances, respectively. The pitches of the respective pairs of the magnetic and non-magnetic portions are arranged with pitches different with each other by the predetermined distances. Output signals transmitted from the detecting heads in accordance with the relative movement between the rod member and the detecting heads are detected by phase detectors, and on the basis of the detected signals, the predetermined operation is carried out in an operation processing unit thereby to obtain the absolute positional relation between the rod member and the detecting heads in, for example, of a positioning system such as in a die casting machine.

Abstract: In a sensor having a drive winding for establishing a forward field, an electrically conductive screen is displaceable relative to a sense winding. In the presence of the drive field, eddy currents are generated in the screen to establish a counter-field opposing the forward field, so that the sense winding is shaded by the screen to a varying extent during relative displacement of screen and sense winding and the voltage induced in the sense winding is accordingly correspondingly varied. Application of a high frequency input to the drive winding results in a modulated output from the sense winding which may be demodulated to provide a signal indicative of screen position relative to sense winding. The position signal may be further processed to provide a speed signal. The sensor may assume a multiplicity of linear or planar, rotational and axial or solenoidal configurations.

Abstract: A speed detecting device for an electric motor in which the angular stopping position of a rotary shaft is controlled with a high precision. A magnet is mounted on a rotary shaft of the motor, and a position detector detects the position of the magnet as rotated by the motor, thereby producing an output signal having a linear region. A speed calculator samples this signal in the liner region at predetermined time intervals and performs a division operation whereby a difference between a present sampled value and a preceding sampled value of the output signal is divided by the time interval, thereby to produce a speed signal which is applied to the motor as a control signal.

Abstract: An xy-surface drive of limited .phi.-rotation and z-movement, has three box coils, positioned at mutual angles of 120.degree., the coils being mechanically connected to each other, and guided in the working air-gap of the magnet ring segment system such that when current flows through the coils, there a power or momentum results, which moves and/or rotates the coil arrangement which, by means of an electrodynamic system, is deflectably connected in z-direction to the object support only via a plate spring. The coil arrangement is connected to an incremental x-y-.phi.-measured value indicator, so that a position control connects the coils according to the deviation to the voltage sources of various polarity, so that the ideal position is attained. The z-position is optimized via an analyzer of object sharpness and a position control.

Abstract: An aligner or positioning system for moving a member in any direction in a horizontal plane includes a planar member having an upper horizontal surface and a platform movable above the horizontal surface. Driving coils extending along either of two orthogonal directions are disposed in one of the members while a pattern of oppositely magnetized permanent magnet elements is disposed in the other in flux coupling relationship. Energization of windings in appropriate senses, in accordance with the position of the platform, generates relative movement in one or both of two orthogonal directions, which may include angular movement as well.

Abstract: Servoing is accomplished utilizing the same read head and the same data track by utilizing a differentially sensitive magnetic sensor. The sensor is utilized as the data read back head sensitive element but separate outputs from the differential sensor are supplied to separate track following amplifiers isolated from the data signal amplifier. The separate amplifiers for the servo information utilize the inherent differential sensitivity of the sensor. As one-half or the other of the differentially sensitive sensor drifts over the edge of a recorded data track, its signal output level will follow. This differential between the left and right halves of the sensor in the form of a change in signal level at the output can be amplified, referenced to common ground for high common mode noise rejection, and a differential signal derived from the difference between the left and right halves of the sensor.

Abstract: A positioning device having a plate-shaped carrier (5) which is displaceable in a horizontal plane and which is journalled on a table (1) and on which is exerted a pressure and tensile force, respectively, by means of at least two translation drives (11, 13). The translation drives (11, 13) are coupled to the carrier (5) by means of horizontally operating static thrust and tensile bearings, respectively (33 to 41, 49), which transfer via a viscous medium in a contactless manner pressure and tensile forces respectively, between the carrier (5) and the translation drives (11, 13). The contactless bearings (33 to 41, 49) are pre-stressed with a force which is larger than the maximum occurring tensile force between the drives (11, 13) and the carrier (5). Thus, a substantially frictionless coupling is obtained between the drives (11, 13) and the carrier (5). This coupling acts at the same time as a guide for the carrier (5).

Abstract: This device comprises a first detector having a first rotor and a first stator for detecting an absolute rotational position within one cycle which corresponds to 1/N circumference, said rotor having teeth of N, and a second detector having a second rotor coupled with the first rotor and a second stator for detecting an absolute rotational position within one circumference within one cycle which corresponds to one circumference. The first and second stators are respectively provided with primary coils and secondary coils. The respective primary coils are excited by reference AC signals generated in response to a clock pulse signal from a clock pulse generator. Phase differences between first and second output signals produced from the secondary coils of the respective detectors and the reference AC signals are obtained by counting the clock pulse signal.

Abstract: The relative orientation of a probe and a surface is maintained by positioning a proximity sensor off-axis on the probe, rotating the probe, and using the signal from the probe to adjust the relative orientation in a feedback loop.

Abstract: An electromagnetic position control apparatus including a rotary sphere having a permanent magnet. The rotary sphere is rotably supported within a spherical hole formed at a crossing portion of a cross-shaped yoke. Coils are used to create magnetic fields at the rotary sphere. The position of rotation of the rotary sphere is controlled in three dimensions by means of changing the intensity of the direct current supplied to the coils or the duty cycle of the pulse current supplied to the coils to change the intensity of the magnetic fields.

Abstract: A position sensor comprises n tracks (Sp.sub.1, Sp.sub.2, Sp.sub.3) on a carrier (T) which are provided with magnetizations of a length L and of alternate polarity. The tracks are phase-shifted with respect to each other by .DELTA.L=L.sub./n. A sensor head (S) comprises Permalloy-resistors (R.sub.1, R.sub.2, R.sub.3) above each track (Sp.sub.1, Sp.sub.2, Sp.sub.3) whereat the maximum distance d of the Permalloy-resistors (R.sub.1, R.sub.2, R.sub.3) from the tracks does not exceed essentially the length L (FIG. 1).

Abstract: An automatic tracking welding machine includes a pair of rotatably mounted sensors 6a, 6b disposed in advance of a welding torch 3 and coaxial therewith for detecting magnetic leakage flux across a weld line gap 10. The sensors are driven to equalize their outputs by a reversible stepping motor 15 supplied with drive pulses whose frequency is proportional to the sensor output difference up to a fixed limit, thereby implementing slowdown as the center or zero differential point is approached. Alternatively, a greater number of fixed sensors may be peripherally spaced around the torch housing and their outputs sequentially scanned and peak detected to track the weld line gap. In another embodiment a spaced pair of sensors 116a, 116b is laterally and bidirectionally driven by a reversible d.c. motor 123 supplied with a voltage proportional to the off-center distance detected by the sensors, thus also implementing slowdown as the zero point approaches.

Abstract: This invention is directed to an actuator which is particularly adapted among many other possible uses, or use in adjusting the configuration of deformable mirrors.

Abstract: The invention relates to a method and apparatus for the lateral positioning of a member relative to a joint formed between two metal surfaces and having discontinuities.Use is made of an eddy current sensor having at least two probes staggered in the direction of the joint. The signals supplied by each probe are processed separately to obtain a signal representing the lateral displacement. By comparing said signal with a given threshold below the amplitude of the signal in the presence of a discontinuity, it is possible to only transmit to a servomotor signals which are below this threshold, which correspond to an effective measurement of the lateral displacement.Application is to automatic welding machines.

Abstract: This invention is directed to electromagnetic alignment apparatus, which is particularly adapted, among other possible uses, for use in aligning the wafers in a microlithography system, said apparatus comprising in combination a first magnetic circuit having a plurality of elements including a first magnet; a second magnetic circuit having a plurality of elements including a second magnet; the second magnetic circuit being disposed in spaced relationship with respect to the first magnetic circuit; a movable structural component adapted for mounting an object thereon; one element of each magnetic circuit being fixedly attached to the movable structural component; first and second current carrying coil assemblies mounted in the first magnetic circuit; the second coil assembly being disposed at an angle with respect to the first coil assembly; third and fourth current carrying coil assemblies mounted in the second magnetic circuit; the fourth coil assembly being disposed at an angle with respect to the third coi

Abstract: This invention is directed to electromagnetic alignment apparatus, which is particularly adapted, among many other possible uses, for use in aligning the wafers in a microlithography system, said apparatus comprising in combination three or more spaced magnets, three or more coil assemblies mounted to pass through the magnetic fields of the magnets respectively, means for controlling the flow of current through the coil assemblies respectively, said coil assemblies being joined together to form a structure movable with respect to the magnets and adapted to carry an object thereon, the coil assemblies being wound with respect to each other so that by controlling the supply of current to the coils the structure can be moved selectively in three degrees of freedom.

Abstract: This invention is directed to electro-magnetic alignment apparatus, which is particularly adapted, among many other possible uses, for use in aligning the wafers in a microlithography system, said apparatus including in combination at least three magnet assemblies which are mounted in space relationship one with respect to the others, at least three coil assemblies mounted to pass through the high flux region of the magnet assemblies respectively, the width of the coil assemblies being substantially less than the width of the high flux regions respectively, a controller for controlling the flow of current through the coil assemblies respectively, a structural assembly for connecting the coil assemblies which is movable with respect to the magnet assemblies, the coil assemblies being wound with respect to each other so that by controlling the supply of current to the coils the structure assembly can be moved selectively in three degrees of freedom.

Abstract: Positioning device for a printer comprising a type carrier daisy wheel fitted on a carriage movable in front of the platen. The selection of type and movement of carriage are carried out by selection and transport motors of direct current type which are controlled by velocity servo motors through corresponding digital transducer and position counters. After a coarse positioning by the servo motor, the exact final position is reached and kept by exciting a couple of magnetic positioners whose rotor is keyed on the axes of the selection and transport motors.Economic solutions are also described to synchronize, during initialization of the machine, the content of the position counters with the effective positions of the daisy wheel and carriage.

Abstract: A stabilizing system for isolating a load device from vibrations of a supporting structure includes a pivotal member and a spring isolator connecting the load device to the supporting structure. Servo controlled actuators are connected across the pivotal member to rotate and torque the load relative to the isolator to compensate for angular displacement of the supporting structure and isolator relative to the load device. An inertial sensor secured to the load device provides a reference for the servo control.

Abstract: This invention is directed to electro-magnetic alignment devices, which are particularly adapted, among other possible uses, for use in aligning the wafers in a microlithography system, said devices comprising in combination a base plate, a first current carrying coil assembly mounted on the base plate, a second current carrying coil assembly mounted on the base plate in spaced relationship with respect to the first coil assembly, a first magnet mounted adjacent the first coil assembly and a second magnet mounted adjacent the second coil assembly, an upper connecting piece connecting the first and second magnets, a mount for receiving an object on the upper connecting piece, the base plate and magnets and upper connecting piece coacting to form a magnetic circuit, a controller for controlling the flow and direction of current through the coil assemblies to move the magnets and upper connecting piece with respect to the base plate, a plurality of linear actuators mounted between the magnets and the upper conne

Abstract: An ultrasound probe includes an acoustical mirror that deflects an ultrasound beam generated by an ultrasound crystal toward an object under examination. The probe includes a thin flat motor whose rotor is controlled by a control system. The control system creates commutating signals that are applied to stator coils of the motor. An error signal that is related to the difference between the actual and desired positions of the object rotated by the motor is applied to the commutating signals to alter their amplitude or polarity to change the torque developed by the motor.

Abstract: A speed control circuit and position control circuit are connected to a spindle drive motor in a machine tool or the like in order to drive the spindle at a predetermined speed and stop the spindle at a predetermined angular position. When an orientation command is issued while the spindle is being rotated at the predetermined speed by a speed control loop, a speed command signal from a speed command circuit is interrupted, the speed reduced to zero, and an initially set voltage is then employed as a speed command to rotate the spindle by a predetermined amount. Next, a integral value of the actual spindle speed is employed as the speed command to further rotate the spindle by a predetermined amount. When this has been accomplished, a constant bias voltage of a low level replaces the speed command, thereby to rotate the spindle still further by a predetermined amount until a specified portion of the spindle approaches extremely close to the predetermined angular position.

Abstract: In an apparatus having an objective lens for projecting a light spot on a track of a disc-shaped record medium, the objective lens is driven in a tracking direction perpendicular to an optical axis of the objective lens and to a track tangential direction in accordance with a tracking error signal representing a deviation of the light spot from the track by means of a tracking control mechanism including first and second permanent magnets, first and second magnetic members connecting the same poles of the permanent magnets, a third magnetic member holding the objective lens and arranged movably in the tracking direction within a space surrounded by the first and second permanent magnets and first and second magnetic members, and first and second coils wound around the first and second magnetic members at middle portions thereof.

Abstract: A prosthesis comprising:(a) a gripping member;(b) an operating lever mounted to pivot about a pivot axis and operatively connected to the gripping member;(c) a power unit including an electric motor, and a drive shaft rotatable by said electric motor;(d) means connecting the drive shaft to the operating lever at a region spaced from the said pivot axis of the operating lever, said connecting means being constructed so that when the drive shaft rotates the connecting means (and also the region of the operating lever connected to the shaft) travels axially along the shaft thereby causing the operating lever to pivot about its pivot axis; and(e) means pivotally mounting said power unit to allow the connecting means to move along an arcuate path about the pivot axis during pivoting of the operating lever.

Abstract: A magnetic transducer is provided having a plurality of magnetic poles arranged annularly about an axis to form a stator coacting with a rotor which rotates about the same axis to induce changes in the magnetic forces between the poles. Each of the poles in the stator has a sense coil thereon for generating an electric output signal in response to the induced changes in flux. At least one pair of these magnetic poles have the same polarity and are positioned substantially 180.degree. apart. The sense coils on each of the poles in this pair are connected in series so that the resulting output electrical signal from these coils would be cumulative.

Abstract: A control circuit for stopping a spindle at a predetermined rotational position, of the type having a position sensor for producing a zero volt signal when a specified point on the spindle arrives at the predetermined rotational position, and for producing a voltage which is positive or negative when the specified point on the spindle is in the vicinity of the predetermined rotational position on either the left or right side thereof. The control circuit includes an orientation control circuit for stopping the spindle drive motor when the output signal from the position sensor attains the value of zero volts, thereby stopping the specified point on the spindle at the predetermined rotational position. The control circuit further includes a position adjustment circuit for adjusting the rotational position, of the specified point on the spindle, at which the output signal from the position sensor crosses the zero volt line.

Abstract: Apparatus is disclosed for controlling the movement of a movable element to bring said movable element to rest at a desired stopping position. The apparatus comprises a multi-phase drive motor having a drive shaft coupled to the movable element for driving same, a plurality of electrically conductive coils mounted in position-displaced relationship about the shaft, and means coupled to the drive shaft and responsive to the selective energization of the coils by respective motor drive signals for causing the corresponding rotation of the drive shaft and movement of the movable element. A sensor is coupled to the drive shaft and is responsive to the rotation thereof for generating an electrical signal containing information indicative of the direction, speed and distance of movement of said movable element. Further, means are included for detecting from the distance information indicated by the electrical signal whether the movable element is within a predetermined distance of the desired stopping position.

Abstract: Mechanically programmable hydraulic linear positioner providing a primemover with the ability to assume and maintain accurately any of an arbitrary number of preselected programmed positions, and to quickly reposition the load from one such preselected detent position to another detent position upon command. A Hall effect magnetic field sensor detects load position and generates command signals directly controlling a proportional hydraulic valve. Rotary and manual positioning applications are described.

Abstract: A control system for stopping a spindle at a predetermined rotational position, for driving a spindle in such a manner that a positional deviation between the present rotational position of a specified point on the spindle and a predetermined rotational position at which the specified point is to be stopped, is reduced to zero, thereby to stop the specified point on the spindle at the predetermined rotational position. First and second rotational position sensors are attached to the spindle at first and second specified points thereof, the position at which at least the first rotational position sensor is attached being adjustable. Further provided are changeover means and an orientation control circuit. The first position sensor produces a rotational position deviation signal when a tool is inserted into and withdrawn from a workpiece at the time of a boring operation, and the second position sensor produces a rotational position deviation signal when tools are changed.

Abstract: Apparatus is disclosed for controlling the movement of a movable element to bring the movable element to rest at a desired stopping position. The apparatus comprises a multi-phase drive motor having a drive shaft coupled to the movable element for driving same, four electrically conductive coils mounted in position-displaced relationship about the shaft, and means coupled to the drive shaft and responsive to the selective energization of the coils by respective motor drive signals for causing the corresponding rotation of said drive shaft and movement of said movable element. A sensor is coupled to the drive shaft and is responsive to the rotation thereof for generating an electrical signal containing information indicative of the direction, speed and distance of movement of said movable element. Further, means are included for detecting from the distance information indicated by the electrical signal whether the movable element is within a predetermined distance of said desired stopping position.

Abstract: A control system for stopping a spindle at a prescribed rotational position having a position control loop for driving a spindle so that a positional deviation between the present rotational position of a specified point on the spindle and a predetermined rotational position at which the specified point is to be stopped, is reduced to zero to stop the specified point on the spindle at the predetermined rotational position. Fine and coarse voltage signals are utilized for the final positioning process.

Abstract: In a printer comprising a printing head, which is supported by a carriage, the carriage position along a record carrier is sensed at two occasions. A cooperating micro processor calculates an actual carriage speed on the basis of the position values which are obtained. The actual carriage speed and an optimal carriage speed, which is stored, are compared and on the basis of this comparison a compensation factor is calculated for a reference signal (Ref) which determines the carriage speed. This compensation factor is checked at each carriage movement by measuring the carriage speed. Accordingly a permanently optimal carriage speed is secured and the need of an accurate trimming of the carriage speed is eliminated during manufacture as well as at later service periods.

Abstract: A plurality of slots are disposed at equal angular intervals on one portion of a circular ring-shaped field magnet fixed to a motor's rotor to run radially of the magnet. Alternatively, short rods made of a soft magnetic material may extend radially outwards from the lateral surface of the magnet to form the slots between them. Three magnetic sensor elements are disposed at equal angular intervals of 120 degrees on a motor's stator to face successively the slots during the rotation of the rotor.

Abstract: A tachometer for generating a velocity signal in a data disc pack servo system comprising a sampling pulse generator for producing pulses that are spaced from one another by a constant amount representative of a distance increment of radial movement of a servo head in the system, a timer for measuring the time between the sampling pulses, the timer including a clock pulse source and a counter which is started by one sampling pulse and reset by the next succeeding sampling pulse so that the digital output thereof is proportional to time and a computer for computing average velocity by deriving the quotient of the distance increment divided by the time required for the servo head to traverse such distance increment.

Abstract: A device for controlling the speed of movement of a mobile member relative to a fixed support member, said mobile member receiving its motion from first drive means is described. The main feature of said drive is that it comprises a speed transducer operated directly by said mobile member and arranged to supply an electrical signal proportional to said speed of movement of said mobile member to second comparison and processing means, to said second means there being also fed at least one electrical reference signal proportional to a predetermined value of said speed; the output signal of said second means, proportional to the difference between said signal of said transducer and said electrical reference signal, being fed to said first drive means.

Abstract: A linear variable phase transformer position to phase transducer produces a linear phase change in an output signal with respect to displacement. Moreover, the magnitude of such output signal remains relatively constant while such displacement occurs. The transducer includes two primaries which are specially wound according to sine and cosine functions and are excited out of phase, a secondary, and a core that combines the primary signals and induces the output signal in the secondary according to the core position relative to the primaries.

Abstract: A rotary actuator comprise a stator defining a cylindrical space and formed with a pair of diametrically opposite main magnetic poles adapted to be magnetized to the same polarity, a pair of drive coils disposed on the main poles, a drive circuit for energizing the drive coils, and a rotor having a plurality of pairs of magnetized zones separated by non-magnetized zones, all disposed around the circumference of the rotor, adjacent magnetized zones being of opposite polarities.

Abstract: A method is provided for adjusting or setting a definite position of rest of a rotary tube, particularly of a tube mill, by switching off the drive of the tube and is particularly characterized in that, at a time T.sub.o, the angular position of the rotary tube, or of a drive part rotating with a tube, referred to a plane of comparison is established, that the idling movement of the tube is predetermined between disconnection and final standstill, and the angular position of the rotary tube and/or of the time T.sub.x at which the drive is disconnected is calculated and effected.

Abstract: A position indicating unit of sewing machines, and more particularly a position indicator installed in sewing machines, having a magnet, pole plates, Hall effect ICs, amplifying actuating circuits and a visual signaling device to indicate and monitor the operation of automatic needle position control system, and to cause a conventional needle braking mechanism or the like to stop the sewing machine at a given position.

Abstract: A time optimal function generator in a coarse positioning system for magnetic heads in a magnetic disc device is designed to accelerate the magnetic heads as rapidly as possible to the exact point at which they must decelerate as rapidly as possible to stop at the new track location when moving from an old track location. This device uses as an input the output of a difference register which contains the difference between the present track address and the new track address. The system is designed to control the servo transducer positioning system in a generally linear fashion as it approaches the new track address but in a square root fashion when the difference is large. The system contains a square root response portion and a linear response portion with weighting devices to control the proportional response of the system.

Abstract: The value of three components of an analog signal are compared with zero and in two's compared with one another. Each possible combination of the comparison result, within the range of possible phase argument values of the analog signal, has correlated therewith a respective zone, whereby there is formed a coarse interpolation of a period of the analog signal into phase zones. The components are digitized and there are selected the components having the smallest (X), the intermediate (Y) and the largest (Z) absolute value. There are formed the digital functions H=Y-X and K=Z-Y+X. Each possible combination (H, K) is correlated to a respective predetermined number of steps of the phase argument within the zone, thereby producing a fine interpolation of the zone into steps. Preferably, at the beginning there is substracted from each analog component one-third of the sum of the three components.

Abstract: Apparatus is provided for sensing the actual position of an armature in an electromagnetic driver, such as a torque motor, a solenoid, or the like. An oscillator generates a relatively high frequency carrier signal, which is superimposed on a relatively low frequency command signal supplied to a drive coil. Detector coils are positioned in a magnetic circuit, and are arranged to have induced therein, signals identical in frequency to the superimposed signals. The amplitude of the induced signals varies with armature position. The high frequency induced signal is separated and demodulated to provide an output signal indicating the actual position of the armature.

Abstract: During the access mode of a movable magnetic head in a disk file, a program of position control signals is derived from a simulator, the input of which is clocked at sector time intervals. The position control signals of the simulator are periodically transferred to the summing point of a servo loop which successively is error conditioned, dependent on the subsequent nominal magnetic head positions derived from the simulator. Servo sectors on the data disk are sampled by the magnetic head, evaluated and converted to a digitally coded position error signal. The error signal is summed with a digital position control signal, and the output sum signal in analog form is applied to the motor that drives the head. The track following function is accomplished by means of a closed servo loop, which is also used in the access mode.

Abstract: A sewing machine, wherein a stitch controlling instrumentality is positioned during operation of the machine by a motor acting through connecting linkages, is provided with a ring magnet that is connected to said linkages for angular displacement thereby about its axis and with a linear output Hall effect sensor that is disposed within the ring magnet to produce an output voltage proportional to displacement of the stitch forming instrumentality.

Abstract: Apparatus for tracking a seam between two work members comprising a sensor including a housing with an insulating mounting board therein carrying two first ferrite cores and two second ferrite cores on the upper surface thereof, the two first ferrite cores being each curved in planes normal to the board and each having the faces at the ends thereof lying in a common plane with the first ones of the faces thereof in alignment along a longitudinal axis in the board, the two second ferrite cores being each curved in planes normal to the board and each having a first one of the faces at the ends thereof lying in the common plane and spaced laterally of the longitudinal axis equidistantly, two first coils wound around the first cores and connected in series aiding relation to two second coils wound around the second cores, a signal generator connected to the coils and means for comprising the combined permeabilities in the flux paths of each first core and associated second core with the other first core and its a