Hamamatsu Proposes ToF Sensor with Potential Adjusting Nodes

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Hamamatsu patent application US20140071429 "Range sensor and range image sensor" by Mitsuhito Mase and Takashi Suzuki proposes to use circular transfer gates 5 and potential adjusting gates 6 to maximize a fill factor of ToF sensor. Basically, the whole area outside of transfer gate 5 generates photoelectrons:

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