Nonlinear digital transducer based on the Gray's encoding

An analogic-digital transducer based on the Gray's encoding method for detecting the position of a movable member, comprising an encoding card mechanically connected to said movable member, the encoding card being equipped with a grid of opaque and transparent windows with sequences of elementary windows arranged perpendicularly to the direction of the displacement, said sequences being in a number equal to that of the encoded values corresponding to the different positions of the movable member, and with sequences of elementary windows arranged in the direction of the displacement, said sequences being in a number equalling that of the binary digits which compose the same encoded values, said transducer comprising a series of photodiodes and a series of phototransistors in a number equalling that of the elementary windows which compose the binary digits of each of the encoded values, said photodiodes and said phototransistors being fixed relative to the encoding card and being confrontingly positioned with the encoding card interposed therebetween and with a collimating member capable of concentrating the luminous radiation of the photodiodes onto the phototransistors, the transducer further comprising a circuitry of comparators operatively connected with said phototransistors and capable of squaring up the voltage signal delivered by each phototransistor for comparison with a preselected voltage threshold, said transducer being characterized by an encoding card wherein the gap between the encoded displacement values is variable as a function of the same values taken by the displacement in the field of variation thereof and the width of the elementary opaque and transparent windows, as measured in the direction of the displacement, is variable and is equal to the gap width.