Interpolation network for discrete displacement measurement transducer - uses light source moving along axis w.r.t. photocell array producing outputs phase-shifted by discrete amounts

摘要

A simple discrete displacement transducer logic interpolator produces, typically, twenty interpolated intervals in each primary interval, using only simple squaring and gating networks. The interpolator can be applied to an array of photocells arranged along an axis and subjected to an illumination of intensity varying sinusoidally w.r.t distance along that axis. The illuminating source along the axis concerned w.r.t the photocell array, producing photocell outputs shifted in phase w.r.t each other by fixed discrete amounts, depending on the velocity of the light source. The photocell outputs are fed in pairs to an array of linear comparator circuits and the square wave outputs of these are taken to an arran of AND gates. The outputs of these are in turn, fed to two OR gates to produce two square waveforms at ninety, one delayed on the other by a quarter period and both running at five times the original photocell output frequency.