Time-of-Flight Photodiode Array Segmentation for Pulse Detection
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Solution Overview
Problem
Conventional LiDAR systems face challenges in accurately detecting the entire reflected pulse due to the time-of-flight effect, where only a portion of the pulse is detected within the emitted pulse time slot, limiting the precision of distance calculation.
Innovation Solution
A photodiode array with multiple photodiodes arranged in groups, each with independently controlled timeslots, allowing for the detection of various portions of the reflected pulse, including ambient light, and a controller to determine the timing and length of these timeslots for precise distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single photodiode with a single integration time is used, then the device complexity is low, but the measurement precision of distance calculation deteriorates because only a portion of the reflected pulse is detected
Solution Approach 1:
The single photodiode is segmented into multiple photodiodes (first, second, third photodiodes), each dedicated to detecting a specific portion of the reflected pulse. This segmentation allows the system to capture the entire reflected pulse by dividing it into detectable segments, thereby improving distance calculation precision while managing device complexity through structured organization.
2Measurement precision
If the integration time is extended to capture the entire reflected pulse, then the measurement precision improves, but the reliability deteriorates due to ambient light interference
Solution Approach 1:
The detection process is segmented into multiple independent photodiodes with different integration times. The first photodiode captures early portions with shorter integration time avoiding ambient light, while subsequent photodiodes capture later portions with extended integration times. This segmentation allows the system to capture the entire reflected pulse without prolonged exposure to ambient light interference.
Solution Approach 2:
The first photodiode performs preliminary detection of the early reflected pulse portion before ambient light becomes significant. This preliminary action captures the initial signal with high reliability, and subsequent photodiodes continue the detection sequence, maintaining overall reliability while achieving complete pulse capture.
3Reliability
If multiple photodiodes with different integration times are used, then the reliability of distance measurement improves by capturing the entire reflected pulse, but the device complexity increases
Solution Approach 1:
The system segments the reflected pulse detection into multiple photodiodes, each handling a specific time portion. This segmentation improves reliability by ensuring complete pulse capture, while the modular structure manages complexity through organized division of detection tasks across multiple specialized components.
Solution Approach 2:
The multiple photodiodes operate in a periodic sequence with different integration times, systematically capturing portions of the reflected pulse at different time intervals. This periodic action ensures complete pulse detection for reliable measurement while organizing the complex multi-photodiode system into a regular, manageable operational pattern.
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
Enables accurate detection of the time-of-flight and distance calculation by capturing all portions of the reflected pulse, improving precision and reliability across various distances without ambient light interference.
Implementation Method 1
an array of photodiodes arranged in groups, each group including at least a first photodiode, a second photodiode and a third photodiode... facilitating detection of light by the first photodiode during a first timeslot, detection of light by the second photodiode during a second timeslot, and detection of light by the third photodiode during a third timeslot
Implementation Method 2
a shutter for controlling integration time of each of the first, second and third photodiodes in the groups, facilitating detection of light by the first photodiode during a first timeslot
Data Source
AI summary
An array of photodiodes is provided, the array including a plurality of photodiodes arranged in groups, each group including at least a first photodiode, a second photodiode and a third photodiode; and a shutter for controlling integration time of each of the first, second and third photodiodes in the groups, facilitating detection of light by the first photodiode during a first timeslot, detection of light by the second photodiode during a second timeslot, and detection of light by the third photodiode during a third timeslot. The first, second and third timeslots are independently controlled allowing thereby detecting various portions of light radiation.