초록

An electro-optical range finder using three modulation frequencies for providing light beams to be projected. The device is characterized by the fact that the highest frequency is not an approximation to the other two frequencies but the other two frequencies are approximation to each other.

대표청구항 ▼

In an electro-optical range finder including: projector means for radiating a ray of light having a given modulation frequency; light-receiving means for receiving the ray of light reflected by a reflector positioned at a measuring point and for converting it into an electric signal; a mixer for mix

In an electro-optical range finder including: projector means for radiating a ray of light having a given modulation frequency; light-receiving means for receiving the ray of light reflected by a reflector positioned at a measuring point and for converting it into an electric signal; a mixer for mixing the electric signal from said light-receiving means and a reference signal; and an arithmetic circuit for computing the distance between the measuring point and the range finder positioned at a setting point by the change in phases between the signal from said mixer and a divided signal of said modulation frequency; the improvement wherein said projector means further includes means for selectively radiating the rays of light with first, second and third modulation frequencies which are different from each other, said first modulation frequency having a value at least ten times higher than said second and third modulation frequencies, and said second and third modulation frequencies being approximations to each other within a maximum limit of ±20%.