ToF Sensor Pixel Photogate Phase Signal Segmentation
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Solution Overview
Problem
Existing 3D imaging devices using Time of Flight (ToF) sensors face challenges in accurately acquiring depth information, especially at longer distances, due to motion artifacts and the need for additional frame memory.
Innovation Solution
A ToF sensor design that includes pixel groups with photogates configured to output phase signals with specific phase differences, allowing for the generation of depth information from a single frame and reducing memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ToF sensor methods are used to acquire depth information, then high-speed operation and reduced noise are achieved, but motion artifacts and motion blur appear due to object motion
Solution Approach 1:
The pixel array is divided into first pixel groups and second pixel groups, where first photogates in first pixel groups receive light during a first time period and second photogates in second pixel groups receive light during a second time period. This temporal segmentation allows depth information to be acquired simultaneously without motion artifacts by processing different time intervals for different pixel groups within the same frame.
2Adaptability or versatility
If traditional ToF sensor methods are used to generate depth information maps, then depth mapping capability is achieved, but additional frame memory is required to calculate depth values
Solution Approach 1:
The patent merges the acquisition of multiple phase signals into a single frame period by organizing photogates in different pixel groups to operate simultaneously at different time intervals. This eliminates the need for separate frame memories to store multiple frames for depth calculation, as all necessary information is captured in one frame.
3Measurement precision
If multiple frames with phase differences are used to generate depth information, then depth accuracy is improved, but processing time and computational complexity increase
Solution Approach 1:
The photogates are pre-configured with different time periods (first time period and second time period) before the light reception process. This preliminary timing arrangement enables the system to capture phase-shifted information simultaneously within a single frame, eliminating the need for sequential frame acquisition and 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
The proposed solution effectively reduces motion artifacts and memory requirements, enabling accurate and efficient acquisition of depth information across various distances and environments.
Implementation Method 1
a first photogate configured to receive light reflected by an object and generate a first phase signal
Implementation Method 2
acquire depth information of the object by measuring a time taken for a light receiver of the ToF sensor to receive infrared rays reflected by the object
Data Source
AI summary
A time of flight (ToF) sensor includes: a first pixel including a first photogate to receive light reflected by an object and generate a first phase signal, and a second photogate to generate a second phase signal having a phase difference of 180 degrees with respect to the first phase signal; a second pixel including a third photogate to receive the reflected light and generate a third phase signal different from the first phase signal and a fourth photogate to generate a fourth phase signal having a phase difference of 180 degrees with respect to the third phase signal; a first signal output unit to output the first and second phase signals; and a second signal output unit to output the third and fourth phase signals, wherein the first, second, third and fourth photogates output the first to fourth phase signals during a frame period.