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AssigneeCeskoslovenska akademie ved
InventorsPavel Sedlacek, Jiri Hajek
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A technique for sensing the relative position of a cursor or other indicator integral with an inductive sensing element along at least one coordinate of a specified area is described. An array of conductors are sequentially arranged along the coordinate and are sequentially excited by a sequence of adjacent, substantially rectangular voltage pulses to yield an overlapping current distribution to simulate a continuous travelling-wave magnetic field along the coordinate. The induced voltage response of the sensing element is a continuous wave form which passes through a predetermined level at a time, relative to the start of movement of the travelling wave magnetic field, that is indicative of the relative position of the element along the coordinate. A threshold detector element which outpulses an indication upon the attainment of such specified value of induced voltage response is coupled, along with a signal indicative of the start of excitation of the conductors, to suitable digital comparison circuitry to yield a position read-out of the system.
In a method of electromagnetically determining the relative position of an inductive sensing element along a specified first direction, the method comprising the steps of exciting an array of parallel conductors sequentially arranged in the first direction and disposed in magnetic coupling relation with the sensing element with current pulses to vary the induced voltage response of the sensing element, and measuring the time of occurrence of a prescribed value of such induced voltage with respect to the start of an excitation interval of the conductors as a measure of the distance, in the first direction, of the sensing element from a reference point, the improvement wherein the excitation step comprises energizing the conductors by a consecutive sequence of adjacent substantially rectangular voltage pulses to yield a resultant substantially continuous, travelling-wave magnetic field along the first direction to produce a correspondingly continuous induced voltage response in the sensing element and in which the measuring step comprises determining the instant relative to the start of the energization of the conductors at which the continuous voltage response induced in the sensing means reaches a predetermined value in a prescribed sense.
In an apparatus including an array of parallel conductors sequentilly arranged transversally in a first direction for sensing the relative position, in such first direction, of an inductive sensing element disposed in magnetic coupling relation to the array of conductors, means for generating a sequence of adjacent substantially rectangular voltage pulses, means for exciting successive ones of the conductors in the array with successively adjacent ones of the voltage pulses to produce in said conductors an overlapping current distribution which yields a substantially continuous, travelling-wave magnetic field along the first direction to correspondingly generate a continuous induced voltage response of the sensing means, threshhold circuit means coupled to the output of the sensing means for producing an output indication when the continuous induced voltage response of the sensing means reaches a predetermined value in a prescribed sense, and means for detecting the interval between the start of excitation of the conductors and the occurrence of the output indication from the threshhold circuit means.
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