Range Imaging Charge-Ratio Correction for Distance Accuracy
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Solution Overview
Problem
Existing range imaging devices face errors in distance measurement due to signal delays and varying charge transfer efficiencies, leading to inaccuracies in calculated distances.
Innovation Solution
A range imaging device that includes a light source, a light-receiving unit with charge storage units, and a processing unit that uses table information to determine distances based on electric charge ratios, correcting for signal delays and charge transfer efficiencies by employing correspondence tables and linear interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential charge distribution to three charge storage units is used for distance calculation, then distance measurement capability is achieved, but measurement precision deteriorates due to signal delays and varying charge transfer efficiencies
Solution Approach 1:
The patent pre-calculates and stores correction values in a correction value storage unit before actual distance measurement. These correction values compensate for signal delays and charge transfer efficiency variations that would otherwise degrade measurement accuracy. By performing this correction preparation in advance, the system eliminates the need for complex real-time calculations during measurement, thereby maintaining high precision without being affected by temporal variations in charge transfer efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the measured distance and charge distribution information are used to retrieve pre-stored correction values, which are then applied to refine the final distance measurement. This feedback loop compensates for systematic errors caused by signal delays and varying charge transfer efficiencies, thereby improving measurement precision while maintaining system reliability.
2Measurement precision
If multiple charge storage units are used to improve distance measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent pre-calculates correction values based on the known characteristics of the multiple charge storage units and stores them in advance. This preliminary action eliminates the need for complex real-time processing of charge distribution data during actual measurement, thereby maintaining measurement precision while significantly simplifying the operational complexity of the pixel circuit structure.
Solution Approach 2:
The patent uses multiple charge storage units with identical or similar structures, where each unit follows the same charge distribution and readout pattern. This copying approach allows the system to leverage the simplicity of a single unit's design while benefiting from the enhanced precision that multiple units provide, thereby improving measurement accuracy without proportionally increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurate distance measurements are achieved by correcting for signal delays and charge transfer inefficiencies, enhancing the precision of range imaging.
Implementation Method 1
a photoelectric conversion element and charge storage units, the photoelectric conversion element generates electric charge corresponding to incident light
Data Source
AI summary
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.