Patent ID: 7379163

Claim:
For use with a time-of-flight (TOF) system that illuminates a target, a distance z from said TOF system, with emitted optical energy having a modulated periodic waveform that includes a high frequency component, and that detects a fraction of said emitted optical energy with an array of pixel photodetectors operable in at least two phases to determine data proportional to said distance z, said TOF system operable to determine distance z independently of reflectivity of said target, a method to automatically control detection gain of said pixel photodetectors, the method comprising the following steps: (a) identifying which of said pixel photodetectors are receiving excessive levels of emitted optical energy to output reliable detection data, which of said pixel photodetectors are receiving insufficient levels of emitted optical energy to output reliable detection data, and which of said pixel photodetectors are receiving adequate levels of emitted optical energy to output reliable detection data; (b) designating one of at least three groups into which pixel photodetectors identified in step (a) are placed, comprising (i) said pixel photodetectors receiving excessive levels of emitted optical energy, (ii) said pixel photodetectors receiving insufficient levels of emitted optical energy, and (iii) said pixel photodetectors receiving adequate levels of emitted optical energy; and (c) if a highest number of said pixel photodetectors are members of a group comprising (i) said pixel photodetectors receiving excessive levels of emitted optical energy, varying at least one system parameter associated with said TOF system to reduce levels of emitted optical energy presented to said pixel photodetectors; and if a highest number of said pixel photodetectors are members of a group comprising (ii) said pixel photodetectors receiving insufficient levels of emitted optical energy, varying at least one system parameter associated with said TOF system to increase levels of emitted optical energy presented to said pixel photodetectors.