TOF range image sensor using a range-shift technique

In time-of-flight (TOF) range image sensors using periodical pulsed light, there is a trade-off between the maximum range and range resolution. This paper proposes a technique for improving range resolution of the TOF range image sensor using range shifting. In the TOF range image sensor with ambient light draining structure, the amount of delay of short light pulse is changed depending on the measurement range. This technique improves the range resolution without reducing the measurement range. The use of the small duty-ratio pulse also leads to reducing the effect of ambient light. The range-shift technique is tested with an implemented TOF range image sensor and it is found that the range resolution is improved to 2 cm using 10 ns light pulse and 7 zones for the measurement range of 0.5 m to 4 m.