Patent ID: 7177014
Filing Date: 2007-02-13
Classification: G01S

Abstract:
1. A wave light distance measuring apparatus, comprising: a light source portion for applying a distance measuring light amplitude-modulated with a reference electrical signal as a sine wave signal having a predetermined frequency to an object to be measured; a light receiving portion for receiving the distance measuring light reflected by the object to be measured to convert the received distance measuring light into a received electrical signal; A/D conversion means for A/D-converting the reference electrical signal and the received electrical signal based on a sampling signal; phase difference detecting means for detecting phases of the reference electrical signal and the received electrical signal which are A/D-converted by the A/D conversion means to subtract the phase of the reference electrical signal from the phase of the received electrical signal, whereby detecting a phase difference between the reference electrical signal and the received electrical signal; and distance detecting means for detecting a distance to the object to be measured based on the phase difference detected by the phase difference detecting means, wherein the reference electrical signal has two kinds of frequencies which are different from each other and any one of which is alternatively selected, the sampling signal is synchronized with the reference electrical signal having the two kinds of frequencies once every n times, and a frequency of the sampling signal is equal to an average value of the two kinds of frequencies of the reference electrical signals, and the A/D conversion means carries out at least one A/D conversion per period of the reference electrical signal and the received electrical signal based on the sampling signal.