Auto Exposure Control System with Dynamic Brightness Targeting
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Solution Overview
Problem
Conventional auto exposure systems face issues with local over-exposure in high contrast scenes due to the use of a fixed target brightness value across different environments, leading to brightness oscillation, undershooting, and overshooting.
Innovation Solution
An auto exposure control system with dynamic target brightness control, comprising a mean statistics unit, target control unit, stabilization unit, and exposure value control unit, which generates a weighted mean brightness value and adjusts exposure commands based on ambient light and status information, using delay, jump, sneak, and hysteresis functions to stabilize target brightness values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed target brightness value is used for all environments, then the system is simple and low cost, but it causes local over-exposure in high contrast scenes
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed target brightness value to a dynamically adjusted target brightness value that changes according to ambient light conditions. The system includes an ambient light detection unit that detects ambient light levels and a target brightness control unit that adjusts the target brightness value based on this detection, allowing the system to adapt to different lighting environments and avoid over-exposure in high contrast scenes.
Solution Approach 2:
The patent changes the parameter of target brightness value from a fixed constant to a variable parameter that depends on ambient light conditions. By introducing ambient light detection and using this information to modify the target brightness value, the system achieves more precise exposure control across different environmental conditions while maintaining reasonable complexity through structured parameter adjustment mechanisms.
2Manufacturing precision
If the target brightness value is dynamically adjusted according to ambient light, then exposure precision is improved, but brightness oscillation and overshooting occur
Solution Approach 1:
The patent applies preliminary action by introducing a prediction mechanism that anticipates future brightness changes before they occur. The system includes a prediction unit that predicts future ambient light conditions and adjusts the target brightness value in advance, allowing the exposure system to prepare for upcoming changes and avoid oscillations and overshooting that would result from reactive adjustments.
Solution Approach 2:
The patent implements feedback by creating a closed-loop control system where ambient light detection information is continuously fed back to the target brightness control unit. This feedback mechanism allows the system to monitor actual ambient conditions and adjust the target brightness value accordingly, stabilizing brightness transitions and preventing oscillations through continuous adjustment based on real-time environmental data.
3Speed
If rapid adjustment of target brightness value is made, then response speed is improved, but undershooting and overshooting increase
Solution Approach 1:
The patent applies preliminary action by using prediction to anticipate future brightness requirements before rapid changes occur. The prediction unit analyzes trends in ambient light conditions and prepares adjustments in advance, allowing the system to respond more smoothly to rapid environmental changes without undershooting or overshooting, thereby maintaining both speed and accuracy.
Solution Approach 2:
The patent implements beforehand cushioning by introducing prediction-based preparation that cushions against the harmful effects of rapid changes. By anticipating future brightness requirements and preparing adjustments in advance, the system softens the impact of rapid environmental changes, preventing oscillations and accuracy losses that would otherwise occur during rapid transitions.
Data Source
AI summary
An auto exposure control system includes a mean statistics unit that generates a weighted mean brightness value for an image array; a target control unit that determines a target brightness value according to an ambient status that is determined in accordance with an ambient light value, wherein, in one embodiment, the weighted mean brightness value is used as the ambient light value; a stabilization unit that generates stabilization control signals for the target control unit according to the ambient light value and ambient status information provided by the target control unit; and an exposure value control unit that computes a desired exposure value by comparing the target brightness value with the weighted mean brightness value and determines an exposure command according to the desired exposure value.