Circuit arrangement for detecting markings

摘要

The circuit arrangement according to the main patent... (Patent Application P 3740017.7-53) is intended to be improved to the effect that a shorter signal response time of the evaluation circuit is achieved. Further, the possibility of light/dark detection of marks is intended to be provided. The useful signal is fed to a circuit which contains an amplifier (29) having reverse-connected parallel rectifier elements (30, 31) connected to its output, for splitting the useful signal present in the form of an alternating voltage into positive and negative half-cycles. Furthermore, the circuit has an inverting amplifier (36), and the two positive half-cycles can respectively be connected to a sample-and-hold circuit (38, 39) and have their voltage value doubled in a summing amplifier (40) connected to the output of the two sample-and-hold circuits. <IMAGE>