Patent ID: 7781811

Claim:
A semiconductor range-finding element, comprising: a semiconductor photoelectric conversion element configured to receive an optical pulse, which is reflected by a target sample, as an optical signal, and configured to convert into signal charges in a charge generation region; first and second transfer gate electrodes configured to electrostatically control potentials of first and second transfer channels implemented by a same semiconductor region as the charge generation region through insulating films formed on the first and second transfer channels, respectively, and configured to alternately transfer the signal charges generated in the charge generation region, through the first and second transfer channels; first and second floating drain regions configured to accumulate the signal charges transferred by the first and second transfer gate electrodes, sequentially and respectively; a first exhausting gate electrode configured to electrostatically control a potential of a first exhausting channel implemented by the same semiconductor region as the charge generation region through the insulating film formed on the first exhausting channel and configured to receive a background light and then to exhaust background charges generated in the charge generation region; and a first exhausting drain region configured to receive the background charges exhausted by the first exhausting gate electrode, wherein, by sequentially applying control pulse signals to the first gate electrode, the second transfer gate electrode and the first exhausting gate electrode in synchronization with the optical pulse so as to operate the first gate electrode, the second transfer gate electrode and the first exhausting gate electrode, a range to the target sample is measured in accordance with a distribution ratio between the charges accumulated in the first and second floating drain regions.