Time-of-Flight Sensor Exposure Control for SNR Optimization
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Solution Overview
Problem
Time-of-flight image capture sensors face challenges in exposure control to achieve a better signal-to-noise ratio (SNR) without pixel saturation, as conventional exposure control methods are not directly applicable and require precise management of integration periods to optimize tap values.
Innovation Solution
An exposure control apparatus and method that detect independent and dependent portions of tap values in time-of-flight image capture sensors, adjusting the integration period to ensure the dependent portion aligns with the required tap value, thereby optimizing SNR without saturation, using a detector and controller to manage pixel integration periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration period is increased to improve signal-to-noise ratio, then the SNR improves, but pixel saturation occurs
Solution Approach 1:
The patent applies dynamics by making the integration period adjustable and adaptive rather than fixed. The controller dynamically modifies the integration period based on detected tap value characteristics, allowing the system to optimize between SNR and saturation prevention in real-time. This is achieved by detecting the independent and dependent portions of tap values and adjusting the integration period accordingly to achieve the required tap value without saturation.
Solution Approach 2:
The patent changes the integration period parameter based on the detected tap value analysis. By separating tap values into independent and dependent portions and adjusting the integration period to make the dependent portion equal to the difference between the required tap value and the independent portion, the system optimizes the integration period parameter to achieve desired SNR while preventing saturation.
2Object-affected harmful factors
If the integration period is decreased to prevent pixel saturation, then saturation is avoided, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent implements feedback by detecting the tap values, analyzing their independent and dependent portions, and using this information to adjust the integration period. The controller continuously monitors the tap value characteristics and modifies the integration period to maintain optimal performance, creating a closed-loop control system that balances SNR and saturation prevention.
Solution Approach 2:
The system dynamically adjusts the integration period based on real-time tap value analysis rather than using a fixed value. This dynamic adaptation allows the system to respond to changing lighting conditions and scene requirements, optimizing the balance between capturing sufficient signal and avoiding saturation.
3Ease of operation
If conventional exposure control methods are used, then the control process is simple, but they are not directly applicable to TOF sensors and require precise management of integration periods
Solution Approach 1:
The system performs self-service by automatically detecting the independent and dependent portions of tap values and autonomously determining the optimal integration period. The controller uses the detected tap value characteristics to calculate and apply the appropriate integration period without requiring manual intervention or complex external control mechanisms.
Solution Approach 2:
The patent applies preliminary action by detecting and analyzing the tap value portions before finalizing the integration period selection. The system预先 identifies the independent portion and calculates the required dependent portion, preparing the integration period adjustment in advance to achieve the desired tap value while preventing saturation.
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
This approach effectively controls the integration period to achieve a better signal-to-noise ratio (SNR) in time-of-flight image capture sensors, preventing pixel saturation and enhancing image quality by dynamically adjusting the exposure based on tap value analysis.
Implementation Method 1
time-of-flight image capture sensor comprising an illumination source providing pulsed illumination at a pulse repetition frequency
Data Source
AI summary
Exposure control apparatus to control an integration period of a time-of-flight image capture sensor comprising an illumination source providing pulsed illumination at a pulse repetition frequency, in which each pixel of an array of pixels is represented by multiple pairs of tap values, each pair of tap values being indicative of light sampled according to a pulsed sampling pattern having a respective phase relationship with the pulsed illumination of the illumination source comprises a detector configured to detect, for a selected tap value of a set of one or more target pixels, a portion of that tap value which is independent of the integration period and a portion which is dependent upon the integration period; and a controller configured to select a next integration period for the image capture sensor so that for a next pixel integration of the set of one or more target pixel values, the portion of the largest tap value which is dependent upon the increased integration period is substantially equal to the difference between the required tap value and the portion which is independent of integration period.