Dual Liquid Lens Iris Recognition Focus Control
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Solution Overview
Problem
Existing iris recognition systems face challenges in efficiently acquiring focused images, particularly when the subject's iris is partially hidden due to blinking or other reasons, leading to prolonged recognition times.
Innovation Solution
The system employs two imaging units with liquid lenses that change focal length based on applied voltage, allowing for rapid adjustment and acquisition of in-focus images. One imaging unit captures an image, and the second unit, with a delayed focal change, increases the likelihood of capturing a suitable image even if the first is unsuitable due to blinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple images are photographed at different focus positions, then the likelihood of obtaining a focused image is improved, but the time required for iris recognition increases
Solution Approach 1:
The system performs preliminary focus detection using a first imaging unit before the main imaging unit captures the final image. This preliminary action identifies the optimal focus position in advance, allowing the main camera to capture a focused image on the first attempt without needing to retake multiple images, thereby reducing recognition time while maintaining high reliability
Solution Approach 2:
A focus detection imaging unit acts as an intermediary between the subject and the main imaging unit. This intermediary device detects the optimal focus position and transmits this information to control the main imaging unit, enabling the system to obtain focused images efficiently without requiring multiple capture attempts
2Device complexity
If the camera focuses on a predetermined position, then the imaging process is simplified, but the image may be out of focus if the subject distance changes
Solution Approach 1:
The system dynamically adjusts the focus position based on real-time detection by the first imaging unit. Instead of using a fixed predetermined focus position, the focus point is continuously adapted to match the actual subject distance, ensuring accurate focus while maintaining a relatively simple imaging process through automated control
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 significantly reduces the time required to acquire images suitable for iris recognition, as it ensures that an in-focus image can be obtained quickly, even if the initial image is unsuitable due to eyelid closure.
Implementation Method 1
The system employs two imaging units with liquid lenses that change focal length based on applied voltage
Data Source
Figure 1A~1C
Figure 2~3
Figure 4
AI summary
The image acquiring device 10 includes the voltage control unit 30 which generates first voltage information that can identify voltage applied to the first variable-focus lens 20A included in the first imaging unit 20 installed in a position where a subject can be photographed and whose focal length changes in accordance with an applied voltage, and generates second voltage information that can identify voltage applied to the second variable-focus lens 21A included in the second imaging unit 21 installed in the position where the subject can be photographed and whose focal length changes in accordance with an applied voltage, and the image judgment unit 40 which inputs images from the first imaging unit 20 and the second imaging unit 21, and selects one image taken at an in-focus position among input images, wherein the voltage control unit 30 generates information, as the first voltage information, that can identify each voltage in a time series of voltages whose values change with time, and generates information, as the second voltage information, that can identify that each of the voltages identified by the first voltage information is applied to the second variable-focus lens 21A after a predetermined period of delay.