Camera Aperture Adjustment for Mixed Visible and Infrared Light
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Solution Overview
Problem
Outdoor surveillance cameras struggle to capture clear images at dusk due to the combination of insufficient sunlight and infrared light, as different wavelengths cause images to be blurry, even with autofocusing methods.
Innovation Solution
A camera system with a light-sensing part, diaphragm, and controller that measures the intensity of visible and invisible light and adjusts the aperture based on their ratio to adjust the depth of field, ensuring clear image capture by aligning image planes for both light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the camera uses a single lens for both visible and infrared light, then the device complexity is reduced, but the image clarity deteriorates at dusk when both light sources are present
Solution Approach 1:
The patent applies dynamics by making the aperture dynamically adjustable based on lighting conditions. The aperture size changes automatically depending on whether the scene is captured in visible light, infrared light, or mixed light conditions, allowing the optical system to adapt its depth of field characteristics to match the active light source wavelength.
Solution Approach 2:
The patent changes the aperture parameter (f-stop value) according to the detected light type. When mixed light conditions are detected (dusk), the aperture is adjusted to a specific range that optimizes depth of field for both visible and infrared wavelengths simultaneously, resolving the focus conflict between different light sources.
2Manufacturing precision
If the camera adjusts focus for visible light during daytime, then visible light image quality is improved, but infrared light image quality deteriorates at dusk
Solution Approach 1:
The system dynamically switches between different aperture settings based on the detected light composition. During daytime with strong visible light, the aperture is set for visible light optimization. At dusk when infrared light becomes significant, the aperture automatically adjusts to accommodate both visible and infrared wavelengths, ensuring reliable image quality across varying lighting conditions.
Solution Approach 2:
The patent employs feedback through a light sensing part that continuously monitors the lighting conditions and provides information to the control unit. This feedback mechanism enables the system to detect when infrared light becomes prominent and automatically adjust the aperture accordingly, maintaining image quality for both visible and infrared wavelengths.
3Ease of operation
If the aperture is kept fixed for autofocusing, then the operation simplicity is maintained, but the depth of field adjustment capability is lost when mixed light conditions occur
Solution Approach 1:
The system performs self-service by automatically detecting light conditions and adjusting the aperture without user intervention. The control unit monitors the light sensing part output and autonomously determines the appropriate aperture setting, maintaining operational simplicity while adapting to changing lighting conditions including mixed visible and infrared light scenarios.
Solution Approach 2:
The aperture transitions from a fixed state to a dynamically adjustable state based on lighting conditions. The system maintains simplicity by automating the adjustment process, eliminating the need for manual user input while providing adaptive depth of field control that responds to real-time changes in visible and infrared light composition.
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
The system effectively captures clear images at dusk by adjusting the aperture to align image planes for both visible and invisible light sources, enhancing surveillance functionality during periods of mixed light conditions.
Implementation Method 1
The light-sensing part can receive visible light of a first wave band and invisible light of a second wave band
Implementation Method 2
Since different wavelengths have different indexes of refraction, images formed by different light source of different wavelengths will not be located at the same position on the optical axis of the camera lens
Data Source
AI summary
A camera using an automatically depth-of-field adjusting method includes a camera lens, a diaphragm, a light-sensing part, and a controller. The light-sensing part can receive visible light of a first wave band and invisible light of a second wave band. The controller performs an adjusting procedure, according to which the controller measures a first light intensity of ambient light of a scene relative to the first wave band and a second light intensity of the ambient light relative to the second wave band, and when the controller determines that a ratio of a difference between the first intensity and the second intensity to a sum of the first intensity and the second intensity is less than a predetermined value, controls the diaphragm to adjust an aperture of the diaphragm according to a current focal length of the camera lens.