Range imaging device and range imaging method

A range imaging device, comprising

• a light source configured to emit light pulses to a measurement space;
• a light-receiving unit including a pixel drive circuit and at least one pixel circuit including a photoelectric conversion element, a plurality of charge storage units, and a plurality of transfer transistors;
• a range image processing unit comprising circuitry configured to calculate, based on charge integrated in each of the charge storage units, a distance from the light-receiving unit to an object in the measurement space as a measurement distance;
• and
• a measurement control unit comprising circuitry configured to calculate a thinning time according to integrated charge in the charge storage units, the distance, and intensity of incident light,
• wherein the photoelectric conversion element generates the charge according to the incident light incident from the measurement space targeted for measurement, the plurality of charge storage units has N charge storage units where N≥3 and integrates the charge in a frame cycle, the plurality of transfer transistors is configured to transfer the charge to the charge storage units from the photoelectric conversion element, the pixel drive circuit is configured to turn on or off the transfer transistors for the charge storage units at predetermined integration timing synchronizing with emission of light pulses to distribute and integrate the charge, the thinning time is a number of times thinning processing is performed in which the charge in the charge storage units is not integrated, in terms of an integration time that is a number of times integration of integrating the charge is performed, and the circuitry of the measurement control unit is configured to determine a measurement zone, to which the measurement distance belongs, from among measurement zones which are established according to zone thresholds set according to multiple distances from the light-receiving unit, and control integration of the charge in the charge storage units according to the thinning time set in the measurement zone as determined.

A method for controlling a range imaging device, comprising:

• emitting light pulses in a measurement space targeted for measurement by a light source of the range imaging device;
• turning on or off a plurality of transfer transistors configured to transfer charge to a plurality of charge storage units of the range imaging device from a photoelectric conversion element of the range imaging device;
• calculating, based on charge integrated in each of the charge storage units, a distance from the range imaging device to an object in the measurement space as a measurement distance;
• and
• calculating a thinning time in terms of an integration time according to integrated charge in the charge storage units, the distance, and intensity of incident light,
• wherein the range imaging device includes a pixel drive circuit configured to turn on or off the transfer transistors for the charge storage units at the predetermined integration timing synchronizing with the emission of the light pulses to distribute and integrate the charge, a range image processing unit comprising circuitry configured to calculate, based on the charge integrated in each of the charge storage units, the distance from the range imaging device to the object in the measurement space as the measurement distance, and the measurement control unit comprising circuitry configured to calculate the thinning time in terms of the integration time according to integrated charge in the charge storage units, the distance, and the intensity of the incident light, the calculating the thinning time includes dividing the integrated charge by reference charge as preset reference integrated charge and, using a charge ratio resulting from the division, determining a measurement zone, to which the measurement distance belongs, from among measurement zones established according to zone thresholds set according to multiple charge ratios, and controlling integration of the charge in the charge storage units according the thinning time set in the measurement zone as determined, the thinning time is a number of times thinning processing is performed in which the charge in the charge storage units is not integrated, and the integration time is a number of times integration of integrating the charge is performed, as performed by the measurement control unit.

A range imaging device, comprising

• a light source configured to emit light pulses to a measurement space;
• a light-receiving unit including a pixel drive circuit and at least one pixel circuit including a photoelectric conversion element, a plurality of charge storage units, and a plurality of transfer transistors;
• a range image processing unit comprising circuitry configured to calculate, based on charge integrated in each of the charge storage units, a distance from the light-receiving unit to an object in the measurement space as a measurement distance;
• and
• a measurement control unit comprising circuitry configured to calculate a thinning time according to integrated charge in the charge storage units, the distance, and intensity of incident light,
• wherein the photoelectric conversion element generates the charge according to the incident light incident from the measurement space targeted for measurement, the plurality of charge storage units is N charge storage units where N≥3 and integrates the charge in a frame cycle, the plurality of transfer transistors is configured to transfer the charge to the charge storage units from the photoelectric conversion element, the pixel drive circuit is configured to turn on or off the transfer transistors for the charge storage units at predetermined integration timing synchronizing with emission of light pulses to distribute and integrate the charge, the thinning time is a number of times thinning processing is performed in which the charge in the charge storage units is not integrated, in terms of an integration time that is a number of times integration of integrating the charge is performed, the integrated charge is divided by a reference charge as a preset reference integrated charge, and using a charge ratio resulting from the division, a measurement zone, to which the measurement distance belongs, is determined from among measurement zones established according to zone thresholds set according to multiple charge ratios, and integration of the charge in the charge storage units is controlled according to the thinning time set in the measurement zone as determined.