Patent ID: 6664536
Filing Date: 2003-12-16
Classification: G01D

Abstract:
A method for evaluating a code signal generated by a position measuring system having an encoder with at least one code track and a reference track in which the encoder is interposed between a light source and a light sensor and moves relative to the light source and the light sensor such that the at least one code track and the reference track transmit light from the light source onto the light sensor when the encoder is in a given position relative to the light source, wherein the light sensor generates the code signal as a function of the light transmitted by the at least one code track which is received by transducers of the light sensor, the method comprising the steps of:(A) capturing the amplitude of a reference signal generated as a function of the light transmitted by the reference track which is received by transducers of the light sensor; (B) evaluating the amplitude of the reference signal; and (C) adapting at least one measurement parameter that is relevant for evaluating the amplitude of the code signal on the basis of the evaluation of the amplitude of the reference signal in order to compensate the evaluation of the code signal to changing measurement conditions, wherein the step of adapting includes modifying the exposure time of the light sensor.