Abstract: A linear position sensor assembly includes a moving target and a stationary magnet. A magnetic sensor is placed adjacent to the magnet and senses changes in the magnetic flux density caused by the target moving within a magnetic field generated by the stationary magnet. The magnetic sensor outputs a signal that is linear over nearly the entire length of the target.

Abstract: In an angle-based binary encoded crankshaft position sensing system, a target wheel is coupled to a crankshaft and a single VR sensor is juxtaposed with the target wheel for sensing the angular position of the wheel and, hence, the angular position of the crankshaft. To permit the use of a single VR sensor in conjunction with an angle-based binary encoded system, the periphery of the target wheel is formed with teeth and slots defining a binary pattern. The slots are wider than the teeth, and the depth of the slots relative to the portion of the periphery defining a nominal radius is greater than the height of the teeth relative to the nominal periphery. With this structure, the signal generated by the sensor in response to a slot advantageously is symmetric to the signal generated by the sensor in response to a tooth.

Abstract: A projection screen apparatus for reproducing the coherence between a visual image and associated acoustic signals. The projection screen apparatus includes a sound broadcasting device and screen that is transparent to sound waves disposed between the sound broadcasting device and the audience, whereby the projection of video and sound broadcasting are simultaneously implemented with respect to the audience. The screen includes multiple layers of white fabric that are superimposed and joined together such that the screen provides a surface that is both transparent to sound and sufficiently opaque to view a projected image.

Abstract: An analog angle encoder having a simply constructed magnet assembly, wherein rotation of a magnetic field relative to a magnetosensitive device provides a varying output of the magnetosensitive device that varies sinusoidally with the angle of relative rotation. The simply constructed magnet assembly is of a closed-path geometry composed of a single piece of magnetic material wherein only a first portion thereof is magnetized for providing the aforesaid magnetic field for the sensor. The remaining portion of the magnet material (the second portion) remains unmagnetized and does not substantially influence the magnetic field produced by the first portion any more than, for example, air would cause.

Abstract: Disclosed is an electric motor system with reduced torque ripple comprising a sinusoidally magnetized permanent magnet, a sinusoidal inverter, a higher resolution position sensor, a composite iron stator yoke, a composite reinforced plastic rotor core and shaft; and a high gear ratio gear reduction box. The novel combination of magnet, inverter, sensor, plastic rotor core and shaft and high gear ratio gear box substantially reduces the torque ripple on the shaft of said motor system.

Abstract: A linear position sensor assembly includes a moving target and a stationary magnet. A magnetic sensor is placed adjacent to the magnet and senses changes in the magnetic flux density caused by the target moving within a magnetic field generated by the stationary magnet. The magnetic sensor outputs a signal that is linear over nearly the entire length of the target.

Abstract: A target wheel sensor assembly includes a sensor that is placed near a target wheel. The sensor includes a magnet to create a flux and a sensing element to sense changes in the flux as the target wheel rotates. The target wheel is alternatingly formed with multiple teeth and multiple slots. Each tooth includes a flat portion that is parallel to the bottom of the sensor and a chamfered portion contiguous to the flat portion. The chamfered portion forms an angle, &agr;, with the bottom of the sensor. As the target wheel rotates, the shape of the teeth in conjunction with the slots cause the sensor to output an asymmetric signal. The shape of the signal is used to determine the direction of motion of the target wheel.

Abstract: An analog angle encoder includes a non-magnetic stator which is cup-shaped, having a central post carrying at least one magnetosensitive device, and further including a rotor in the form of a ring captured by the stator, the rotor carrying at least one permanent magnet, wherein the rotor is rotatable relative to the stator. As the rotor rotates relative to the stator, the angle of the incident magnetic field changes relative to the magnetosensitive device, thereby causing the output from the device to vary sinusoidally with angular position. It is preferred to use magnetic configurations other than simple six sided magnets in order to achieve a more uniform magnetic field at the magnetosensitive device, as for example by utilizing cylindrical magnets, arcuate (concave faced) magnets, flat ferromagnetic layer pole pieces, arcuate (concave faced) ferromagnetic layer pole pieces, and ferromagnetic return paths.

Abstract: A target wheel sensor assembly includes a target wheel, a magnet, a magnetic piece, and a coil to sense changes in the magnetic field caused by the rotation of the target wheel. The magnet, the magnetic piece and the coil are configured so that as the target wheel rotates, the coil outputs an asymmetric signal. This asymmetric signal is used to determine the position and direction of motion of the target wheel as it rotates.

Abstract: A target wheel sensor assembly includes a target wheel, a magnet, and a sensing element placed therebetween. The magnet and the sensing element are configured so that as the target wheel rotates the sensing element outputs an asymmetric signal. This asymmetric signal is used to determine the position of the target wheel as it rotates and the direction of motion of the target wheel.

Abstract: A retractable projection screen that is transparent to sound waves and that includes at least two layers of white fabric that are superimposed and joined together. The screen including the two layers of superimposed fabric is rolled onto a rolling-up device, the weighting bar of which is of a sufficient weight for stretching the fabric so that the stretching compensates for the difference in diameter between the two layers when they are rolled up, which makes it possible to avoid the formation of a fold in the inner layer of fabric when the screen is rolled up.

Abstract: A method and an apparatus using the method that generates an index pulse which includes firstly the generation of a first electronic signal which includes a first level and a second level based upon a multiphase sinusoidal motor control circuit. Secondly, the generation of at least a second electronic signal that includes a first level and a second level based upon a multiphase sinusoidal motor control circuit wherein the first electronic signal and the second electronic signal are levelly spaced apart based upon the phase number of the multiphase sinusoidal motor control circuit wherein a set difference in level exists for a first specified period between the first and said the signal. Thirdly, the determination of the index pulse based upon a transition from the first level to the second level of the first electronic signal.

Abstract: In an angle-based crankshaft position sensing system, an electrical circuit is provided for also sensing the direction of rotation of the crankshaft. A slotted target wheel is coupled to the crankshaft and a single dual-element MR sensor is juxtaposed with the target wheel. The elements generate respective detection signals when a slot passes by the elements, with the position of the slot being indicated as being directly under the sensor at the point in time when the detection signals intersect each other. Also, square waves are generated for each detection signal, and when the magnitude of the second square wave is non-zero when the falling edge of the first square wave occurs, a clockwise rotation is indicated. On the other hand, if the magnitude of the second square wave is zero when the falling edge of the first square wave occurs, a counterclockwise rotation is indicated.

Abstract: A detector of position of rotation of a target wheel via the outputs of a differential sensor employing two matched MRs to extract position of rotation information from the target wheel. The target wheel is provided with wide and narrow slots or teeth circumferentially arranged such that, for example, 24 zones are created wherein each zone ranges from the center of a wide slot to the center of a narrow slot, and wherein each zone occupies 15 degrees circumferentially. The two matched MRs of the sensor are powered by matched current sources and matched magnetic biasing and are aligned in the circumferential direction of the target wheel. The MRs generate two angularly offset signals from the passage of a single slot (or tooth) of the target wheel which are input to a signal conditioning circuit. Within the signal conditioning circuit, the two sensor signals are differentially amplified to produce a differential signal whereby the width of the slot is used to encode a binary position pulse.

Abstract: A method is disclosed for equalizing the electrical resistance of two or more magnetoresistor sensor elements positioned on a permanent magnet in a sensor assembly. The method may utilize a laser to reduce the magnetic field of the portion of the permanent magnet underlying the sensor with the higher electrical resistance.

Abstract: An apparatus for detecting precise angular positions of a rotating object. Two magnetoresistors (MRs) are positioned adjacent a target wheel attached to the rotating object, the target wheel having at least one element of finite length. Each MR is responsive to the passage of at least one of the elements as the target wheel is rotated, generating an analog signal with signal transitions between two voltage levels at the passage of the element's leading and trailing edges. The MRs are positioned relative to the elements such that their signals are phase shifted with respect to one another, resulting in time overlapping signals which intersect at a precise angular positions of the target wheel.

Abstract: A rotation sensor includes a binary encoded target wheel and a pair of sensors disposed about the target wheel periphery. One of the sensors provides a signal indicative of the passage of regular angular intervals of the target wheel and the other of the sensors provides binary states corresponding to the regular angular intervals.

Abstract: A rotation sensor has a target wheel including first and second tracks and a dual-element magnetoresistive sensor. Each individual magnetoresistive element is aligned with a respective track of the target wheel to provide substantially inverse resistive changes with the passage of the wheel. One of the tracks is characterized by alternating high and low permeability, such as by a toothed section, and the other of the tracks is characterized by invariant permeability.

Abstract: A rotation sensor for high accuracy angle applications such as internal combustion engine crankshaft position sensing includes a pair of complementary target wheels and a dual-element magnetoresistive sensor. The target wheels are spaced from one another along the rotational axis by a predetermined distance. The individual magnetoresistive elements are similarly spaced one from the other and are influence by the ferrite effects of the target wheels. The spacing of the target wheels and magnetoresistive elements are selected in relation to one another and in relation to the mount of axial play in the crankshaft such that changes in ferrite effects of the target wheels upon the elements due to axial displacements of the crankshaft have minimal effect on the accuracy of the sensing apparatus.

Abstract: It comprises a first assembly (E1) constituted by a neutron radiation source (6), a hydrogenated material block (4) having a recess for receiving said source (6) and a first neutron detector (10); a second assembly (E2) constituted by a hydrogenated material block (14) surrounded by a material stopping the thermal neutrons (18) and a second neutron detector (16) placed in the hydrogenated material block (14); the first assembly (E1) and the second assembly (E2) being placed on either side of the area to be controlled (2). A foldback protective casket (8) can receive the neutron radiation source (6).