Range Imaging Device Multi-Timing Charge Integration
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Solution Overview
Problem
Existing range imaging devices face challenges in accurately measuring distances due to the presence of multi-path light, which can lead to errors in distance calculation.
Innovation Solution
The range imaging device employs a light source that emits light pulses, a light-receiving unit with pixels and a pixel drive circuit, and a range image processing unit that calculates distance based on the trend of features from charge integration in multiple measurements with varying timing relationships between light emission and charge integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TOF range imaging is used, then distance measurement is achieved, but measurement precision deteriorates due to multi-path light interference
Solution Approach 1:
The patent applies periodic action by performing multiple measurements with different integration timings in a cyclic manner. The light source emits light pulses periodically, and the light-receiving unit performs charge integration at multiple different timings across several measurement cycles. This periodic measurement approach enables the system to distinguish single-path light from multi-path light by analyzing the temporal patterns of charge accumulation, thereby resolving the measurement accuracy issue caused by multi-path interference.
Solution Approach 2:
The patent implements parameter changes by varying the integration timing parameter across multiple measurements. Specifically, the light-receiving unit changes the timing at which charge is integrated from the photoelectric conversion element in each measurement cycle. By changing this temporal parameter and analyzing how the measured values differ across measurements, the system can identify and eliminate the effects of multi-path light, thus improving distance measurement precision.
2Measurement precision
If multiple measurements with different timing are performed, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the measurement framework that includes multiple charge storage units and the protocol for performing measurements at different integration timings. The system prepares the necessary charge storage capacity and timing control mechanisms in advance, allowing the multiple measurements to be executed efficiently without extensive reconfiguration. This preliminary preparation reduces the time penalty associated with performing multiple measurements.
Solution Approach 2:
The patent merges multiple measurement functions into a single integrated measurement process. Instead of performing separate measurements that would require sequential processing, the system combines multiple integration timing measurements into a unified measurement cycle where charge is simultaneously accumulated in multiple storage units at different timings. This merging approach reduces the total measurement time while maintaining the precision benefits of multiple timing samples.
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
This approach allows for accurate distance calculation by distinguishing between single-path and multi-path light, reducing errors and improving measurement precision.
Implementation Method 1
Each of the pixels in the light-receiving unit includes a photoelectric conversion element that generates charge according to incident light
Data Source
AI summary
A range imaging device includes a light source unit emitting light pulses to an object; pixels each including a photoelectric conversion element generating charge according to incident light and charge storage units integrating charge; a pixel drive circuit distributing charge to the charge storage units for integration therein at an integration timing synchronized with an emission timing of emitting the light pulses; and a range image processing unit calculating a distance to the object based on amounts of charge integrated in the charge storage units. The range image processing unit performs measurements which are different from each other in relative timing relationship between the emission timing and the integration timing and calculates a distance to the object based on a trend of features according to the amounts of charge integrated in each of the measurements.