Range imaging apparatus and range imaging method

Patent metadata

Field	Value
Publication number	US-2025035790-A1
Application number	US-202418913160-A
Country	US
Kind code	A1
Filing date	Oct 11, 2024
Priority date	Apr 13, 2022
Publication date	Jan 30, 2025
Grant date	—

Abstract

A range imaging apparatus includes a light source unit; a light receiving unit including a pixel having a photoelectric conversion device and charge storages, and a pixel driver circuit that distributes and stores the charge into the charge storages; and a range image processing unit that calculates a distance to a subject in the measurement space are included. Subframes are provided per frame, and the range image processing unit stores the charge by controlling the storage timing such that the storage timing relative to the emission timing is relatively different in each of the subframes, and selects a subframe for calculating the distance from the subframes based on the amounts of charge stored per unit integration count in each of the subframes.

First claim

1 . A range imaging apparatus, comprising:
a light source unit that emits a light pulse to a measurement space; a light receiving unit including a pixel having a photoelectric conversion device configured to generate charge corresponding to incident light and a plurality of charge storages configured to store the charge; and a range image processing unit comprising circuitry configured to calculate a distance to a subject in the measurement space based on amounts of charge stored in the charge storages, wherein the light receiving unit includes a pixel driver circuit configured to distribute and store the charge into the charge storages at a storage timing synchronized with an emission timing at which the light pulse is emitted, and the circuitry of the range image processing unit is configured to store the charge by controlling the storage timing such that the storage timing relative to the emission timing is relatively different in each of a plurality of subframes provided per frame and select a subframe for calculating the distance from the subframes based on the amounts of charge stored per unit integration count in each of the subframes.

2 . The range imaging apparatus according to claim 1 , wherein the circuitry of the range image processing unit is configured to calculate a first indicator corresponding to a magnitude of a reflected light component by using storage signals corresponding to the amounts of charge stored in each of the plurality of subframes, calculate a second indicator by dividing the first indicator by the integration count for each of the plurality of subframes, and select a subframe from the plurality of subframes whose second indicator is the largest as a subframe for calculating the distance.

3 . The range imaging apparatus according to claim 2 , wherein the circuitry of the range image processing unit is configured to calculate the first indicator by using a signal obtained by subtracting an external light signal corresponding to an external light component from the storage signals.

4 . The range imaging apparatus according to claim 2 , wherein the circuitry of the range image processing unit is configured to exclude a subframe whose first indicator is smaller than a threshold from candidates for the subframe for calculating the distance.

5 . The range imaging apparatus according to claim 3 , wherein the circuitry of the range image processing unit is configured to exclude a subframe whose first indicator is smaller than a threshold from candidates for the subframe for calculating the distance.

6 . The range imaging apparatus according to claim 1 , wherein the plurality of subframes includes a first subframe and a second subframe, and the circuitry of the range image processing unit is configured to store the charge in the charge storages of the pixel in each of the subframes in sequence of the first subframe and then the second subframe, and control the storage timing such that a last storage timing, which is a latest timing at which the charge is stored in the charge storage of the pixel in the first subframe, and a first storage timing, which is an earliest timing at which the charge is stored in the charge storage of the pixel in the second subframe, are the same timing relative to the timing at which the light pulse is emitted.

7 . The range imaging apparatus according to claim 6 , wherein the circuitry of the range image processing unit is configured to perform level adjustment by multiplying signal values corresponding to the amounts of charge stored in the charge storages in the first or second subframe by a constant such that a first signal value corresponding to an amount of charge stored in a last charge storage, which is the charge storage in which the charge is stored at the last storage timing, and a second signal value corresponding to an amount of charge stored in an first charge storage, which is the charge storage in which the charge is stored at the first storage timing, are the same, and calculate the distance using the level-adjusted signal values.

8 . The range imaging apparatus according to claim 7 , wherein the circuitry of the range image processing unit is configured to determine whether the charge corresponding to reflected light of the light pulse is stored in the last charge storage, and perform the level adjustment if the charge corresponding to the reflected light is stored in the last charge storage.

9 . A range imaging method, comprising:
storing charge by controlling a storage timing such that the storage timing relative to an emission timing is relatively different in each of a plurality of subframes provided per frame; and selecting a subframe for calculating a distance to a subject in a measurement space from the subframes based on amounts of charge stored per unit integration count in each of the subframes, wherein the range imaging method is carried out by a range imaging apparatus comprising a light source unit that emits a light pulse to the measurement space, a light receiving unit including a pixel having a photoelectric conversion device configured to generate the charge corresponding to incident light and a plurality of charge storages configured to store the charge, and a pixel driver circuit configured to distribute and store the charge into the charge storages at the storage timing synchronized with the emission timing at which the light pulse is emitted, and a range image processing unit comprising circuitry configured to calculate the distance to the subject in the measurement space based on the amounts of charge stored in the charge storages, and the circuitry of the range image processing unit is configured to store the charge by controlling the storage timing and select the subframe for calculating the distance.

10 . The range imaging method according to claim 9 , wherein the plurality of subframes includes a first subframe and a second subframe, and the circuitry of the range image processing unit is configured to store the charge in the charge storages of the pixel in each of the subframes in sequence of the first subframe and then the second subframe, and control the storage timing such that a last storage timing, which is a latest timing at which the charge is stored in the charge storage of the pixel in the first subframe, and a first storage timing, which is an earliest timing at which the charge is stored in the charge storage of the pixel in the second subframe, are the same timing relative to the timing at which the light pulse is emitted.

11 . A range imaging apparatus, comprising:
a light source unit that emits a light pulse to a measurement space; a light receiving unit including a pixel having a photoelectric conversion device configured to generate charge corresponding to incident light and a plurality of charge storages configured to store the charge; and a range image processing unit comprising circuitry configured to calculate a distance to a subject in the measurement space based on amounts of charge stored in the charge storages, wherein the light receiving unit includes a pixel driver circuit configured to distribute and store the charge into the charge storages at a storage timing synchronized with an emission timing at which the light pulse is emitted, and the circuitry of the range image processing unit is configured to calculate an indicator of a degree of variation of an external light signal corresponding to an external light component stored in the charge storages in each of a plurality of subframes provided per frame based on storage signals corresponding to the amounts of charge stored in the charge storages in each of the subframes, and select a subframe for calculating the distance from the

Assignees

• Toppan Holdings Inc

Inventors

• Hatakeyama Kunihiro
• Nakagome Tomohiro
• HARIU Hiromitsu
• Akutsu Takahiro
• Nagase Masanori

Classifications

• G01S17/10

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G01S7/4865

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S17/18

  wherein range gates are used · CPC title

• G01S7/4863 Primary

  Detector arrays, e.g. charge-transfer gates · CPC title

• G01S17/894 Primary

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title