Method and apparatus for optoelectronic contactless range finding using the transit time principle

Abstract

The invention relates to a method for optoelectronic contactless distance or range measurement or finding according to the transit time principle, in which a distance of an object from a sensor unit is determined from a time difference between a starting signal and an echo signal, which is derived from an optical measurement pulse reflected by the object and where for determining the time difference the following steps are performed: a) by comparing the starting signal and echo signal with a digital clock a digital raw value is obtained, b) with the aid of at least two fine interpolators an initial time difference between the starting signal and the beginning of the digital raw value as well as a final time difference between the echo signal and the end of the digital raw value is determined, c) to the fine interpolators are in each case supplied analog signals corresponding to the initial time difference or final time difference, respectively, and converted into a digital initial time difference or digital final time difference, respectively. The method is characterized in that for the automatic calibration of the fine interpolators a plurality of measurements according to steps a) to c) are carried out and, assuming an equal distribution for the probability with which the values in a given value interval for the initial time difference and final time difference are measured, corrections for nonlinearities and/or drifts of the characteristics of the fine interpolators are calculated. The invention also relates to an apparatus for optoelectronic contactless distance or range measurement according to the transit time principle.