Patent ID: 8120761
Filing Date: 2012-02-21
Classification: G01B,G01S

Abstract:
1. A method for position judgment, comprising: emitting from a first light source, a first pulsed light that alternates turning on and turning off at a predetermined interval/phase, towards an object from a first position; emitting from a second light source, a second pulsed light having a different interval/phase from the predetermined interval/phase of the first pulsed light, towards the object from a second position different from the first position; detecting reflected light pulses in series from the first pulsed light and the second pulsed light that are reflected from the object; calculating an absolute value of a difference between brightness of each of the reflected light pulses, wherein the absolute value of the differential brightness substantially eliminates a brightness of a background of the object and is substantially calculated by using the reflected light pulses reflected from the object by the first pulsed light and the second pulsed light; comparing the absolute value of a first of the reflected light pulses with the absolute value of a second of the reflected light pulses; and judging whether the object is approaching or not, in accordance with the comparing the absolute value of a first of the reflected light pulses with the absolute value of a second of the reflected light pulses.