EVALUATION CIRCUIT FOR THE SIGNALS FROM AN ARRAY OF N PHOTOCONDUCTORS WHICH ARE SUCCESSIVELY SCANNED IN A FAST RHYTHM

Apparatus for evaluating signals generated by first and second spatially separated rows of photoconductors positioned with respect to a measuring plane. The outputs of the photoconductors in each of the rows is scanned by a sampling circuit at a predetermined rate, and the outputs of each sampling circuit coupled to at least one evaluation circuit. Each of the evaluation circuits includes an analog-to-digital converter coupled to the output of the associated sampling circuit, and a pair of digital delay circuits having their inputs alternately coupled to the output of the A/D converter. A comparator is provided for comparing a threshold signal generated by a reference generator with the outputs of the digital delay circuits, the comparator generating a digital signal having a value corresponding to the difference between the ratio of the signals at the outputs of the delay circuits and the threshold signal. A computer coupled to the outputs of the comparators in each of the evaluation circuits determines the coordinates of an object traversing the measuring plane.