Time measurement circuit and optoelectronic range finder using such a time measurement circuit

Abstract

The invention relates to a time measurement circuit and an optoelectronic range finder using such a time measurement circuit. The time measurement circuit and for an incoming signal, in such a condition, has a comparator stage for generating a comparator output signal depending on a fulfillment of a criterion by the incoming signal, wherein exceeding or falling below a threshold value is defined as the criterion. Furthermore, a digitization stage is provided, for sampling, which is performed at a defined sampling rate, of an input signal fed to the digitization stage and converting it into digital data containing sampled values for the input signal, and an evaluation unit for determining a chronological location for the incoming signal by evaluating the digital data. A signal generating stage is interconnected between the comparator stage and the digitization stage, which is designed to generate and output, in a chronologically fixed manner dependent on the content of the comparator output signal, a shape signal, which is designed for post-sampling interpolation ability, of known shape. The evaluation unit then determines the time for the incoming analog signal while using a chronological interpolation of the values contained in the digital data and the known shape of the shape signal.

Description

technical field [0001] The present invention relates to a time measuring circuit and a photoelectric distance meter having such a time measuring circuit. Background technique [0002] Various principles and methods for determining a desired distance are known in the field of optical and / or optoelectronic distance measurement. One method is to emit pulses of electromagnetic radiation, such as a laser, towards an object to be measured, and then receive echoes from this object as backscattering objects, wherein the distance to the object to be measured can be determined based on the elapsed time of the pulses . Such pulsed time-of-flight testers (ToF, ie time-of-flight) are widespread as standard solutions in many fields. [0003] Two different schemes are used to detect return pulses. [0004] In the so-called threshold method, a light pulse is detected when the intensity of the radiation incident on the detector of the rangefinder used exceeds a certain threshold, where th...

AI Technical Summary

Problems solved by technology

At close range, the signal can saturate the receiver so that the shape of the transmitted signal is no longer correctly ascertained and the elapsed time is determined with insufficient accuracy

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