Apparatus for determining the position of an edge

Abstract

Abstract AN APPARATUS IS DISCLOSED WHICH COMPRISES A LIGHT SOURCE AND MEANS FOR OSCILLATORY SCANNING OF THE EDGE OF AN OBJECT BY MEANS OF A LIGHT BEAM WHICH AFTER SCANNING IS INCIDENT ON A PHOTOELECTRIC RECEIVER. IN A FIRST EMBODIMENT OF THE INVENTION THE ELECTRIC PULSES GENERATED BY THE RECEIVER ARE SUPPLIED TO A DIFFERENTIATING STAGE WITH FULL WAVE RECTIFIER WHICH IS CONNECTED TO A KNOWN CIRCUIT ARRANGEMENT FOR THE EVALUATION OF ELECTRIC SIGNALS OBTAINED BY THE SCANNING OF SCALE MARKS. IN A SECOND EMBODIMENT THE PULSES ARE CONDUCTED TO A DIFFERENTIATING STAGE WITH A RESONANT AMPLIFIER THAT IS TUNED TO AN EVEN-NUMBER MULTIPLE OF THE SCANNING FREQUENCY. TO THE OUTPUT TERMINALS OF THAT AMPLIFIER IS CONNECTED A PHASE-SENSITIVE RECTIFIER WHICH IS CONTROLLED BY A REFERENCE SIGNAL DERIVED FROM THE SCANNING MOTION. THE OUTPUT SIGNALS OF THIS AMPLIFIER ARE THEN EVALUATED IN KNOWN MANNER, FOR EXAMPLE BY AN INDICATING MEANS. IN A THIRD DISCLOSED EMBODIMENT THE PULSE ARE CONDUCTED TOA SQUARE SHAPER WHOSE OUTPUT IS SERIALLY CONNECTED TO A SYMMETRICAL SHAPING STAGE WHICH IS CONNECTED TO A LOW-PASS FILTER AND AN EVALUATION DEVICE, FOR EXAMPLE A COMPARISON STAGE.

Inventors

• 👤 Knut Heitmann
• 👤 Eckart Schneider

Bibliographic Details