Optical sensor unit for an industrial truck and method of operating same

Abstract

A method is provided for operating an optical sensor unit comprising markings arranged on a piston rod of a cylinder of an industrial truck. The method, comprises the steps of: transmitting optical radiation onto markings arranged on the piston rod receiving optical radiation reflected by the markings arranged on the piston rod detecting an oscillating voltage signal by the receiver from the optical radiation reflected by the markings on the piston rod; converting the voltage signal into a binary digital signal; setting a control current applied to the transmitter as a control variable, specifying a target voltage amplitude from the detected oscillating voltage signal as a reference variable, determining an average actual voltage amplitude over a plurality of voltage fluctuations produced by traversal of a plurality of markings from the respective actual voltage amplitudes of the voltage signals, determining a control deviation value between a target voltage amplitude and an average associated with the actual voltage amplitudes of the voltage signals, and correcting the average associated with the actual voltage amplitudes of the voltage signals by changing the control current in dependence of the control deviation value.