Light Receiving Element for High-Speed Indirect Time-of-Flight Ranging
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Solution Overview
Problem
Existing ranging systems using indirect time of flight methods face challenges in accurately measuring distance when objects or the ranging module move at high speeds, leading to reduced accuracy and potential failure in distance measurement.
Innovation Solution
A light receiving element with a CAPD sensor configuration, featuring a first and second tap with different voltages applied, photoelectric conversion units, accumulation units, and transmission units to accumulate and process charges, allowing for rapid calculation of distance based on phase shift analysis of incident and reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional indirect ToF ranging system is used, then distance measurement can be performed, but the measurement accuracy deteriorates when objects or the ranging module move at high speeds due to the time required to acquire distance information
Solution Approach 1:
The patent divides the photoelectric conversion process into multiple segments by using multiple photoelectric conversion units (first, second, third, fourth units) that operate at different phases. Each unit converts light received during a specific phase interval into electrical signals, allowing parallel processing of distance information across multiple phases simultaneously. This segmentation enables the system to acquire complete distance measurement data faster, reducing the time loss while maintaining high measurement precision even during high-speed movement.
2Speed
If the ranging system processes distance information quickly, then high-speed movement can be accommodated, but the system complexity increases due to multiple photoelectric conversion units and signal processing components
Solution Approach 1:
The patent implements periodic action by operating multiple photoelectric conversion units at different phases (0°, 90°, 180°, 270°) of the modulation frequency. Each unit processes light during a specific phase interval in a periodic cycle, allowing the system to accumulate distance information from all phases through systematic periodic sampling. This periodic approach enables high-speed distance measurement by processing multiple phases in sequence while maintaining a relatively simple structural configuration, thus achieving fast measurement speed without excessive system complexity.
3Measurement precision
If multiple phases are processed simultaneously to improve accuracy during movement, then measurement precision improves, but the device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-organizing the photoelectric conversion units into distinct phase groups (first and second units for one phase, third and fourth units for another phase, etc.) before the measurement process begins. Each unit is pre-configured to capture light during specific phase intervals, and the conversion from light to electrical signals is pre-arranged for parallel processing. This preliminary organization of multiple phases into structured units simplifies the overall processing requirements while maintaining high measurement precision during movement, as the complex multi-phase data collection is already structured and ready for efficient processing.
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 configuration enables high-speed distance measurement with improved accuracy even when objects or the ranging module are in motion, by collectively processing signal values across multiple phases, thereby reducing the time required for distance calculation and minimizing the impact of movement or shake.
Implementation Method 1
a photodiode PD that performs photoelectric conversion on light incident from the outside and generates charges
Data Source
AI summary
A light receiving element includes: a first tap; a second tap; a first photoelectric conversion unit configured to detect a charge generated by photoelectric conversion according to a light amount of incident light in accordance with a voltage applied to the first tap; a second photoelectric conversion unit configured to detect a charge generated by photoelectric conversion according to a light amount of the incident light in accordance with a voltage applied to the second tap; a plurality of accumulation units configured to accumulate the charges generated by the first photoelectric conversion unit and the second photoelectric conversion unit; a plurality of transmission units configured to transmit the charges generated by the first photoelectric conversion unit and the second photoelectric conversion unit to the plurality of accumulation units; and a calculation unit configured to execute calculation based on the charges accumulated in the plurality of accumulation units.