Patent ID: 7196604
Filing Date: 2007-03-27
Classification: G01D,G01F

Abstract:
1. A man-machine interface comprising: at least one planar substrate having formed thereon a magnetic field generator, the magnetic field generator comprising conductive tracks formed on at least two planes defined by the at least one planar substrate; a mounting carrying an intermediate coupling element, the mounting allowing movement of the intermediate coupling element along a measurement direction transverse to the planar substrate in response to a force applied by a user; and a detector operable to detect the position of the intermediate coupling element in a magnetic field generated by the magnetic field generator, wherein the magnetic field generator comprises a transmit aerial and the detector comprises a receive aerial, the transmit aerial and the receive aerial formed by conductive tracks formed on a first planar surface and a second planar surface on either side of a single-layer planar substrate and by through-plated via-holes through the single planar substrate; wherein movement of the intermediate coupling element along the measurement direction varies the electromagnetic coupling between the transmit aerial and the receive aerial; wherein the transmit aerial comprises a first excitation winding and a second excitation winding, the first excitation winding comprising at least one coil which is arranged about a first axis, which is in the plane of the planar substrate, such that in response to current flowing through the first excitation winding, a magnetic field is generated having a component along the measurement direction which varies in accordance with a first function; and wherein the second excitation winding comprises at least one coil which is arranged about a second axis, which is perpendicular to the plane of the planar substrate, such that in response to current flowing through the second excitation winding, a magnetic field is generated having a component along the measurement direction which varies in accordance with a second function which is different from the first function.