Abstract: There is described an apparatus for providing rotary displacement information indicative of the torque applied to a torsion bar which is rotatable relative to a housing, in which the electromagnetic coupling between a transmit aerial fixed relative to the housing and a receive aerial fixed relative to the housing varies in dependence upon first and second resonators fixed to the torsion bar at spaced axial positions. The first and second resonators have respective different resonant frequencies to enable the signal coupled between the transmit aerial and the receive aerial via the first resonator to be distinguished from the signal coupled between the transmit aerial and the receive aerial via the second resonator.

Abstract: There is described a sensor comprising an excitation winding, a signal generator operable to generate an excitation signal and arranged to apply the generated excitation signal to the excitation winding, a sensor winding electromagnetically coupled to the excitation winding and a signal processor operable to process a periodic electric signal generated in the sensor winding when the excitation signal is applied to the excitation winding by the signal generator to determine a value of a sensed parameter. The excitation signal comprises a periodic carrier signal having a first frequency modulated by a periodic modulation signal having a second frequency, the first frequency being greater than the second frequency. In this way, the sensor is well suited to using digital processing techniques both to generate the excitation signal and to process the signal induced in the sensor windings. In an embodiment, the sensor is used to detect the relative position of two members.

Abstract: There is described a sensing apparatus comprising first and second members which are supported relative to each other by a support means. The first member comprises a magnetic field generator for generating a magnetic field and the second member comprises an aerial for monitoring the magnetic field generated by the magnetic field generator. At least one of the first and second members is locally deformable relative to the other of the first and second members in order to vary at least one of the magnetic field generated by the magnetic field generator and the electromagnetic coupling between the magnetic field generator and the receive aerial so that, in response to a local deformation, a signal is induced in the receive aerial indicative of the position of the local deformation.

Abstract: There is described an inductive position sensor in which a signal generator applies a excitation signal to an excitation winding formed on a first member, the excitation winding being electromagnetically coupled to at least two resonant circuits formed on a second member which are spaced from each other along a measurement path. The excitation windings are shaped so that the electromagnetic coupling between the exciting winding and each of the resonators varies along the measurement path. In this way, by applying an excitation signal to the excitation winding, respective different signals are induced in the resonators which depend upon the relative position of the first and second members.

Abstract: A sensor for sensing a parameter such as position, comprises: (i) an excitation winding for example coils (7, 9) in quadrature; (ii) a signal generator (41, 42, 43) operable to generate an excitation signals and arranged to apply the generated excitation signal to the excitation winding; (iii) a sense coil (11) that can be electromagnetically coupled to the excitation winding such that, in response to the excitation signal being applied to the excitation winding by the signal generator, a periodic electric signal is generated in the sense coil that is indicative of the value of the parameter to be measured by the sensor; and (iv) a signal processor (108) operable to process the periodic electric signal generated in the sensor winding to determine a value representative of the parameter being measured.

Abstract: There is described an apparatus which monitors the orientation of or the rotational movement of a substantially spherical body. The apparatus comprises a substantially spherical body with at least one resonant circuit fixed thereto. A transmit aerial generates an alternating magnetic field in the region of space including the spherical body which induces an electric signal in the or each resonant circuit, and a receive aerial receives an induced sense signal generated in response to said induced electric signal in the or each resonant circuit. The electromagnetic coupling between the transmit aerial and the receive aerial via the or each resonant circuit varies in accordance with the orientation of the spherical body so that the induced sense signal in the receive aerial varies in accordance with the orientation of the spherical body.

Abstract: There is described a position sensor comprising at least one planar substrate having formed thereon a magnetic field generator which comprises conductive tracks formed on at least two planes defined by the at least one planar substrate. An intermediate coupling element is operable to move relative to the at least one planar substrate along a measurement direction transverse to the planar substrate, the detector detects the position of the intermediate coupling element in a magnetic field generated by the magnetic field generator. The position sensor has particular application in man-machine interfaces such as push buttons and rotary switches.

Abstract: There is described a sensor comprising an excitation winding, a signal generator operable to generate an excitation signal and arranged to apply the generated excitation signal to the excitation winding, a sensor winding electromagnetically coupled to the excitation winding and a signal processor operable to process a periodic electric signal generated in the sensor winding when the excitation signal is applied to the excitation winding by the signal generator to determine a value of a sensed parameter. The excitation signal comprises a periodic carrier signal having a first frequency modulated by a periodic modulation signal having a second frequency, the first frequency being greater than the second frequency. In this way, the sensor is well suited to using digital processing techniques both to generate the excitation signal and to process the signal inducced in the sensor windings. In an embodiment, the sensor is used to detect the relative position of two members.