Patent ID: 8638425

Claim:
A method of increasing signal-to-noise ratio of a distance-measuring device, the distance-measuring device being utilized for measuring a measured distance between the distance-measuring device and a measured object, the measured distance being longer than a predetermined shortest measured distance and shorter than a predetermined longest measured distance, the distance-measuring device having a light-emitting component for emitting a detecting light, and a first light-sensing component for sensing and accumulating energy of light according to a first shutter periodic signal to generate a first light-sensing signal, the method comprising: the light-emitting component continuously emitting the detecting light to the measured object to generate a reflected light during an emitting period; a delay period after the light-emitting component starts to emit the detecting light, switching the first shutter periodic signal to represent turning-on during a first sensing period for the first light-sensing component to sense and accumulate energy of the reflected light to generate the first light-sensing signal; obtaining a time of flight of light going back and forth between the distance-measuring device and the measured object according to the first light-sensing signal and energy of the detecting light emitted by the light-emitting component during the emitting period; and obtaining the measured distance according to the time of flight; wherein the delay period is calculated according to the predetermined shortest measured distance; wherein the delay period is calculated according to the following formula: T DELAY =2 ×D MIN /C; wherein T DELAY represents the delay period; D MIN represents the predetermined shortest measured distance; and C represents speed of light; wherein relationship between the predetermined longest measured distance and the first sensing period is represented by the following formula: D MAX =2×( T SEN1 +T Delay )/ C; wherein D MAX represents the predetermined longest measured distance; and T SEN1 represents the first sensing period.