Image Sensor Phase Modulation for TOF Depth Accuracy
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Solution Overview
Problem
Time-of-flight (TOF) image sensors experience signal distortion due to aliasing phenomena, leading to wiggling errors during the processing of modulated light signals, which affect the accuracy of depth information acquisition.
Innovation Solution
An image sensor system that generates multiple light signals with different phases, outputs them to an object, receives reflected signals, and processes them to reduce wiggling errors by integrating and demodulating the signals, thereby improving signal fidelity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single modulated light signal is used for TOF measurement, then the processing speed and application range are maintained, but aliasing phenomena occur causing wiggling errors that distort the signal and reduce measurement precision
Solution Approach 1:
The single modulated light signal is segmented into multiple light signals with different phases (e.g., 0°, 90°, 180°, 270°). Each phase-specific signal is processed separately through dedicated pixel circuits, allowing the system to resolve aliasing errors by combining results from multiple phase measurements without requiring a complete system redesign.
Solution Approach 2:
The patent employs periodic modulation of light signals at different phases sequentially. By alternating between different phase signals in a periodic manner and integrating the reflected signals accordingly, the system achieves accurate depth measurement while maintaining compatibility with existing TOF sensor architectures.
2Measurement precision
If multiple light signals with different phases are generated and processed, then wiggling errors are reduced significantly improving depth information accuracy, but the device complexity and processing requirements increase
Solution Approach 1:
Pixel circuits perform preliminary integration of reflected light signals for each phase during the exposure period. This preliminary action accumulates phase-specific signal energy before the final demodulation and combination steps, reducing the overall processing time required while achieving high measurement precision through multiple phase measurements.
Solution Approach 2:
The patent merges multiple phase-specific reflected signal streams into a single integrated output through coordinated pixel circuit operations. By combining the processing of 0°, 90°, 180°, and 270° phase signals within the same pixel circuit architecture, the system achieves accurate depth measurement without proportionally increasing processing time.
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 significantly reduces wiggling errors, enhancing the accuracy of depth information acquisition by up to 50 times compared to traditional methods, resulting in improved image data processing and reduced signal distortion.
Implementation Method 1
generate a plurality of light signals having different phases based on a reference light signal
Implementation Method 2
sequentially output the plurality of light signals to an object
Implementation Method 3
receive a plurality of reflected light signals in which the plurality of light signals are reflected from the object
Implementation Method 4
calculate the distance from a change of a phase
Implementation Method 5
generate a plurality of pixel signals based on the plurality of demodulated signals and the plurality of reflected light signals
Data Source
AI summary
An image sensor including a light signal generator configured to generate a plurality of light signals having different phases based on a reference light signal, a demodulated signal generator configured to generate a plurality of demodulated signals based on the reference light signal, a light source configured to sequentially output the plurality of light signals to an object, a light receiver configured to receive a plurality of reflected light signals in which the plurality of light signals are reflected from the object, and a pixel array configured to generate a plurality of pixel signals based on the plurality of demodulated signals and the plurality of reflected light signals.