Counter for optical displacement measuring system - provides output for microprocessor calculation of displacement from light detectors operating in counter-phase

摘要

The appts. uses a signal conditioning circuit (100) receives signals (A-D) from optical detectors sensing movement of a carriage in forward and reverse directions. The corresponding signal pulses (+n, -n) are provided and applied to counters (101, 102) whose contents are periodically read by a microprocessor (103) driven by a clock (106) whose interval is adjustable. The values are compared by the microprocessor with previous values to determine the displacement in either direction. The values are then output via an interface (105) to a display (104) with seven segment figures. The appts. allows a number of events to be whose number is greater than the counting capacity at each instant of a sequence of intervals, each of which are less than the minimum possible time for the counter to reach a predetermined count value.