Depth Sensor Noise Reduction via Phase-Shifted Photo Gate Signals
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Solution Overview
Problem
Depth sensors face challenges in minimizing noise to acquire accurate depth information, which is essential for generating high-quality three-dimensional images.
Innovation Solution
A depth sensor method and system that generates photo gate signals with specific phase differences and applies them to pixel arrays using different clock frequencies, allowing for interpolation of pixel signals using weights based on Gaussian functions to reduce noise and enhance spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photo gate signals are applied to all rows and columns simultaneously using the same clock frequency, then the measurement speed is high, but the noise in depth information increases and spatial resolution deteriorates
Solution Approach 1:
The pixel array is divided into different groups (rows and columns) that are controlled by different clock signals with different frequencies. This segmentation allows simultaneous acquisition of depth information at different sampling rates, improving both measurement precision and maintaining productivity by processing different regions with appropriate clock frequencies.
Solution Approach 2:
The patent applies dynamic clock frequency control where different clock frequencies are assigned to different rows and columns based on their specific measurement requirements. This dynamic approach allows the system to optimize measurement precision for critical regions while maintaining overall measurement speed through parallel processing.
2Measurement precision
If multiple clock frequencies are used for different rows and columns, then noise is reduced and spatial resolution is improved, but the device complexity increases
Solution Approach 1:
The control circuit is designed to handle multiple clock frequencies using a universal control architecture. The same control logic can manage different frequency assignments for rows and columns, reducing the need for separate dedicated control circuits for each frequency, thereby minimizing the increase in device complexity.
Solution Approach 2:
The patent employs periodic switching between different clock frequencies for different row and column groups. This periodic action allows the control circuit to reuse the same control logic and timing structures at different time intervals, reducing the overall complexity compared to maintaining completely independent control paths for each frequency.
3Measurement precision
If photo gate signals with 90-degree phase differences are generated, then depth measurement capability is enhanced, but the signal processing complexity increases
Solution Approach 1:
The photo gate signals with 90-degree phase differences are generated in advance through dedicated phase shift circuits before being applied to the pixel array. This preliminary generation of phase-shifted signals simplifies the overall signal processing by pre-establishing the required phase relationships, reducing the complexity of real-time signal manipulation during depth measurement.
Data Source
AI summary
A method of operating a depth sensor includes generating a first photo gate signal and second through fourth photo gate signals respectively having 90-, 180- and 270-degree phase differences from the first photo gate signal, applying the first photo gate signal and the third photo gate signal to a first row of a pixel array and the second photo gate signal and the fourth photo gate signal to a second row adjacent to the first row in a first frame using a first clock signal, and applying the first photo gate signal and the third photo gate signal to a first column of the pixel array and the second photo gate signal and the fourth photo gate signal to a second column adjacent to the first column in a second frame using a second clock signal.