Distance measuring device and method thereof

Abstract

A distance measuring device is provided that reduces the time required for a distance measurement without degrading accuracy of the measured value. The distance measuring device includes a reference signal oscillator () that generates a reference signal (K), a light source () that emits a distance measuring light (L) modulated based on the reference signal, a light receiving element () that receives the distance measuring light reflected from a target () and converts the distance measuring light to a distance measuring signal (M), a frequency converter () that converts the distance measuring signal to an intermediate frequency signal, an A/D converter () that samples the intermediate frequency signal in synchronization with the reference signal, a memory () that stores data of the sampled intermediate frequency signal, and a CPU () that calculates a distance based on the intermediate frequency signal data, the CPU calculates amplitude of each frequency of the intermediate frequency signal based on the intermediate frequency signal data, determines an average of the amplitude, and ends sampling to calculate a distance when the number of pieces of the intermediate frequency signal data is equal to or more than a minimum required number and the average has become equal to or more than a predetermined value.