Range imaging device and range imaging method

Patent metadata

Field	Value
Publication number	US-12506985-B2
Application number	US-202318355978-A
Country	US
Kind code	B2
Filing date	Jul 20, 2023
Priority date	Jan 21, 2021
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

A range imaging device includes a light source unit, a light-receiving unit that includes pixel driving circuit and a pixel including a photoelectric conversion element and charge storage units, a storage unit that stores table information in which electric charge ratios are associated with corresponding distances to an object, and a range image processing unit that determines a measured distance to an object using the table information and the amounts of electric charge accumulated in the charge storage units. The range image processing unit calculates the electric charge ratio based on the amounts of electric charge accumulated in the charge storage units, acquires the corresponding distance associated with the calculated electric charge ratio from the table information, and determines the measured distance using the acquired corresponding distance.

First claim

The invention claimed is:

1 . A range imaging device, comprising:
a light source configured to emit an optical pulse to a measurement space; storage circuitry that stores table information in which an electric charge ratio is associated with a corresponding distance to an object; light-receiving circuitry including a pixel driving circuit and a pixel including a photoelectric conversion element and a plurality of charge storage circuits; and range image processing circuitry configured to determine a measured distance to the object in the measurement space using the table information and an amount of electric charge accumulated in each of the charge storage circuits, wherein the photoelectric conversion element in the pixel of the light-receiving circuitry generates electric charge corresponding to incident light, the plurality of charge storage circuits in the pixel of the light-receiving circuitry stores the electric charge, the pixel driving circuit in the light-receiving circuitry is configured to distribute and accumulate the electric charge in each of the charge storage circuits in the pixel at a predetermined time in synchronization with emission of the optical pulse, the range image processing circuitry is configured to
calculate the electric charge ratio based on the amount of electric charge accumulated in each of the plurality of charge storage circuits,
acquire the corresponding distance associated with the calculated electric charge ratio from the table information, and
determine the measured distance using the acquired corresponding distance.

2 . The range imaging device according to claim 1 , wherein the storage circuitry stores the table information for each first variable based on an amount of electric charge accumulated per unit accumulation count, the table information indicating a relationship between a second variable based on the electric charge ratio and the corresponding distance associated with the distance to the object, the first variable is a variable corresponding to a sum of amounts of electric charge accumulated in the charge storage circuits per unit accumulation count, the second variable is a variable corresponding to an electric charge ratio indicated using an amount of electric charge for distance calculation, the amount obtained by subtracting an ambient light component from the amount of electric charge accumulated in, among at least three charge storage circuits, each of at least two charge storage circuits for distance calculation in which an amount of electric charge corresponding to reflected light being the optical pulse reflected from the object is distributed and accumulated, and the range image processing circuitry calculates the first variable and the second variable based on the amount of electric charge accumulated in each of the charge storage circuits, selects the table information corresponding to the calculated first variable, acquires the corresponding distance associated with the calculated second variable using the selected table information, and determines the measured distance using the acquired corresponding distance.

3 . The range imaging device according to claim 2 , wherein the electric charge ratio is a ratio of the amount of electric charge for distance calculation in one or a combination of the at least two charge storage circuits for distance calculation to a sum of the amounts of electric charge for distance calculation accumulated in the charge storage circuits for distance calculation.

4 . The range imaging device according to claim 2 , wherein the range image processing circuitry calculates the first variable and the second variable based on the amount of electric charge accumulated in each of the charge storage circuits, selects the table information corresponding to the calculated first variable, extracts, from the selected table information, a first distance associated with an electric charge ratio smaller than the second variable and a second distance associated with an electric charge ratio greater than the second variable, and determines the measured distance through linear interpolation between the extracted first distance and the extracted second distance.

5 . The range imaging device according to claim 2 , wherein the pixel includes the at least three charge storage circuits, and the range image processing circuitry determines a smallest amount of electric charge among the amounts of electric charge accumulated in the at least three charge storage circuits, as an amount of electric charge corresponding to the ambient light component.

6 . The range imaging device according to claim 2 , wherein the pixel includes the at least three charge storage circuits, and the range image processing circuitry controls timing of accumulation of electric charge in a predetermined charge storage circuit for storing ambient light among the at least three charge storage circuits so as not to accumulate electric charge corresponding to the reflected light in the charge storage circuit for storing ambient light, and determines the amount of electric charge accumulated in the charge storage circuit for storing ambient light as an amount of electric charge corresponding to the ambient light component.

7 . The range imaging device according to claim 2 , wherein the storage circuit stores first table information being the table information associated with the first variable being smaller than a threshold, and second table information being the table information associated with the first variable being greater than the threshold, the threshold is a value determined in accordance with charge transfer efficiency on a path from the photoelectric conversion element to the charge storage circuit, and the range image processing circuitry calculates the first variable and the second variable based on the amount of electric charge accumulated in each of the charge storage circuits, selects the first table information when the calculated first variable is smaller than the threshold, and selects the second table information when the calculated first variable is greater than the threshold.

8 . The range imaging device according to claim 2 , wherein the storage circuitry stores the table information for each combination of two of the charge storage circuits for distance calculation, and the range image processing circuitry determines, among the at least three charge storage circuits, a combination of the charge storage circuits for distance calculation to be a combination of two of the charge storage circuits storing electric charge successively and having a total amount of accumulated electric charge greater than an amount of electric charge accumulated in another combination of two of the charge storage circuits, and selects the table information in accordance with the determined combination of the charge storage circuits for distance calculation.

9 . The range imaging device according to claim 2 , wherein the pixel includes a first charge storage circuit, a second charge storage circuit, and a third charge storage circuit as three charge storage circuits, and the range image processing circuitry performs control in such a way that the first charge storage circuit, the second charge storage circuit, and the third charge storage circuit store the electric charge in stated order in synchronization with the emission of the optical pulse, uses a first amount of electric charge accumulated in the first charge storage circuit and a third amount of electric charge accumulated in the third charge storage circuit to calculate a first calculated value being a difference between the first amount of electric charge and the third amount of electric charge, and determines the first calculated value as the am

Assignees

• Toppan Inc

Inventors

• Hatakeyama Kunihiro
• Nakagome Tomohiro

Classifications

• G01S7/4876

  by removing unwanted signals (G01S7/495 takes precedence) · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01C3/08

  Use of electric radiation detectors · CPC title

• G01S7/4863

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

• H04N5/33

  Transforming infrared radiation (cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20) · CPC title