3D Image Sensing With Phase-Based ToF Offset Compensation
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Solution Overview
Problem
Existing 3D image sensors, particularly those using Time-of-Flight (ToF) technology, suffer from global offsets due to changes in the operating environment, such as temperature, leading to inaccuracies in depth measurement.
Innovation Solution
A 3D image sensing system that incorporates phase detection pixels and a processing unit to compensate for global offsets using a lookup table based on triangulation principles, enhancing accuracy by correcting ToF distances with a global compensation coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ToF sensors are used without compensation, then the device complexity is low, but the measurement precision deteriorates due to global offsets from environmental changes
Solution Approach 1:
The system performs preliminary calibration to generate a lookup table that maps temperature values to global offset compensation values. This pre-computed compensation data is stored and applied during operation, eliminating the need for complex real-time calculations and achieving high measurement precision without excessive device complexity
Solution Approach 2:
The patent introduces temperature sensors and a lookup table as intermediary elements between the environment and the ToF measurement system. The temperature sensor detects environmental changes, and the lookup table translates these changes into compensation values, mediating the effect of environmental variations on measurement accuracy
2Measurement precision
If real-time compensation calculations are performed, then the measurement precision improves, but the processing time increases
Solution Approach 1:
The compensation values are pre-calculated and stored in a lookup table during system calibration. During operation, the system only needs to retrieve the appropriate compensation value based on the current temperature, avoiding time-consuming real-time calculations while maintaining high measurement precision
Solution Approach 2:
The system uses a simple lookup table structure that requires minimal processing resources. Instead of implementing complex real-time compensation algorithms, the system employs a lightweight data retrieval operation that is computationally inexpensive and extremely fast to execute
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 system significantly improves the accuracy of depth measurement by eliminating global offsets, ensuring that ToF distances more accurately reflect true depths.
Implementation Method 1
ToF is accomplished by using specially designed pixels to measure the round-trip time of flight for photons
Implementation Method 2
at least one phase detection pixel pair is provided in the photosensitive array, and the phase detection pixel pair is configured to provide a disparity for eliminating the global offset of the ToF distance
Data Source
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AI summary
Disclosed are a three-dimensional image sensing system (10) and a related electronic device (60), and a time-of-flight ranging method. The three-dimensional image sensing system (10) comprises: a light-emitting module (110) for emitting incident light; a photosensitive module (100) for receiving reflected light, the photosensitive module (100) comprising a condenser lens (105) for focusing the reflected light into focused reflected light, and a photosensitive array (101), which comprises a first photosensitive element and a second photosensitive element (310) for respectively receiving first focused reflected light and second focused reflected light of the focused reflected light; and a processing unit (120) for executing time-of-flight ranging so as to obtain a first distance corresponding to a target object (200), wherein the first distance has a global offset. The processing unit (120) establishes an image on the basis of the first focused reflected light and the second focused reflected light, estimates a disparity reflected by the first focused reflected light and the second focused reflected light in the image, and calculates a global compensation coefficient on the basis of the disparity to compensate the global offset.