Photo Sensor Block Exposure Control via Motion Prediction
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Solution Overview
Problem
Conventional photo sensors use global signals to control exposure time uniformly across all pixels, leading to over-exposure in high-light conditions and under-exposure in low-light conditions, as they do not adjust exposure times based on varying lighting conditions.
Innovation Solution
A photo sensor array is divided into blocks with individually adjustable exposure times, using a predictive algorithm to estimate light brightness from prior frames and generate exposure time information for each block, which is stored in memory and used to control the exposure duration of each block's pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If global signals are used to control exposure time uniformly across all pixels, then device complexity is reduced and ease of operation is improved, but image quality deteriorates due to over-exposure in high-light conditions and under-exposure in low-light conditions
Solution Approach 1:
The pixel array is divided into multiple blocks, where each block can have independently controlled exposure time. This segmentation allows different regions of the sensor to be exposed for different durations based on local lighting conditions, resolving the contradiction between uniform control simplicity and differential exposure quality.
Solution Approach 2:
Each block within the pixel array is assigned customized exposure time parameters based on its specific lighting conditions. This local quality approach enables high-light regions to use shorter exposure times (preventing over-exposure) while low-light regions use longer exposure times (preventing under-exposure), thereby improving overall image quality without requiring complex per-pixel control.
2Manufacturing precision
If exposure time is adjusted individually for each pixel based on lighting conditions, then image quality is improved, but device complexity increases due to the need for per-pixel control circuits and timing signals
Solution Approach 1:
Instead of controlling each pixel individually, the system segments the pixel array into blocks and controls exposure time at the block level. This reduces the number of control circuits and timing signals required compared to per-pixel control, while still achieving differential exposure benefits.
Solution Approach 2:
Multiple pixels within each block share common control circuits and timing signals for exposure time adjustment. This merging of control resources reduces overall device complexity while maintaining the ability to apply different exposure times to different blocks based on their lighting conditions.
3Measurement precision
If motion prediction is performed on prior frames to generate exposure time information, then exposure accuracy is improved by reducing over-exposure and under-exposure, but processing time and computational resources increase
Solution Approach 1:
Motion prediction is performed on prior frames to pre-determine exposure time information for upcoming frames. This preliminary action allows the system to anticipate lighting conditions and motion, generating appropriate exposure time settings in advance, thereby improving exposure accuracy without adding significant processing delay during actual image capture.
Solution Approach 2:
The system uses its own previously captured frames to generate motion prediction and exposure time information, rather than requiring external input or complex real-time analysis. This self-service approach leverages existing data to improve exposure accuracy while minimizing additional computational overhead and 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
This approach ensures that each block of pixels is exposed for the optimal duration, reducing over-exposure and under-exposure issues and resulting in correctly exposed images by dynamically adjusting exposure times based on predicted light intensities.
Implementation Method 1
The pixels include photodiodes and transistors controlling an exposure duration of the photodiodes
Data Source
AI summary
A photo sensor array is divided up into multiple blocks that are operated with different exposure times. A prediction algorithm is used to predict the overall light brightness of each block and determine the exposure time of each block. Each block may also include memory to store the exposure time for the pixels in the block as well as analog-to-digital resolution for the block.