P-Iris Lens Calibration via Stepping Motor Feedback
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Solution Overview
Problem
Conventional automatic iris lenses lack control over the absolute position of the iris opening, affecting image quality, depth of field, and resolution, especially in varying light conditions, making it difficult to develop control algorithms for optimizing optical performance.
Innovation Solution
The method involves adjusting the iris opening between predefined positions using a stepping motor, with a motor driver controlling the diaphragm blades to maintain optimal image quality by altering the iris position based on light conditions, and using software to optimize image sensor settings, allowing for precise control of the iris opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an adjustable iris is used to control light level, then image exposure can be optimized, but control over the absolute position of the iris opening is lost, affecting image quality and resolution
Solution Approach 1:
The system uses feedback by capturing images at different iris positions and analyzing them to determine which position provides the best image quality. The analysis unit evaluates image quality metrics and feeds this information back to the control unit, which then adjusts the iris to the optimal position, creating a closed-loop control system that resolves the contradiction between light control and position precision.
Solution Approach 2:
The camera system performs self-calibration by automatically capturing test images, analyzing their quality, and determining the optimal iris position without external intervention. The image analysis unit processes the captured images to identify the best iris opening position, enabling the system to self-optimize its performance rather than requiring manual calibration.
2Extent of automation
If a DC iris or video iris is used for automatic adjustment, then response to light level changes is improved, but the circuitry complexity increases and control over absolute iris position is not available
Solution Approach 1:
The invention replaces complex analog circuitry with a digital control approach. Instead of using DC iris or video iris circuitry that converts analog signals to motor control signals, the system uses a stepping motor controlled digitally by the camera's processor. The control unit sends digital commands to position the iris at specific steps, simplifying the overall system architecture while maintaining automatic adjustment capability.
Solution Approach 2:
The camera's existing image sensor and processor are used for multiple purposes: capturing images for normal operation and capturing test images for iris calibration. The image analysis unit leverages the same processing capabilities to evaluate image quality and determine optimal iris positions, eliminating the need for separate dedicated calibration hardware and reducing overall device complexity.
3Illumination intensity
If the iris opening is made small to control light in bright conditions, then light level is reduced, but diffraction and blurring increase, degrading image quality
Solution Approach 1:
The system changes the parameter of iris opening size to an optimal value rather than simply reducing it. By using image quality analysis to determine the best iris position, the system identifies the point where further closing would cause diffraction to degrade image quality. This allows the system to maintain the largest possible aperture that still provides adequate light control, avoiding the harmful effects of excessive diffraction.
Data Source
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AI summary
The invention relates to a calibration method in a camera with a P-Iris lens having an adjustable iris opening. The calibration comprise the steps of adjusting the size of the iris opening between a first opening position and a second opening position, recording a plurality of images during the adjusting, analyzing the images, and determining an iris opening, based on the analysis, that obtains a high quality image