Aperture Stop with Rotatable Blades for LED Flicker Mitigation
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Solution Overview
Problem
Automotive cameras face image deterioration due to temperature variations and LED flicker, which current aperture stops struggle to mitigate effectively, especially in varying lighting conditions, leading to issues with exposure time and dynamic range.
Innovation Solution
An aperture stop with a housing and rotatable blades forming variable-sized incident holes, driven by a magnet and coil system, allowing for multistage adjustment of light exposure to address LED flicker and dynamic range challenges, incorporating blocking spacers and materials like carbon-based oxides to reduce flaring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture stop has a relatively small diameter, then LED flicker mitigation can be implemented by exposing for a time longer than the LED blinking period, but the dynamic range decreases due to image saturation in daytime environments
Solution Approach 1:
The aperture stop employs multiple blades that can rotate independently to dynamically adjust the aperture size. This dynamic adjustment capability allows the system to optimize the balance between exposure time and aperture diameter in real-time, resolving the contradiction between LED flicker mitigation and dynamic range preservation
Solution Approach 2:
The system changes the aperture diameter parameter to be variable rather than fixed. By adjusting the aperture diameter in conjunction with exposure time, the system can maintain optimal image quality across different lighting conditions while mitigating LED flicker effects
2Illumination intensity
If the aperture stop has a relatively large diameter to prevent image saturation and maintain dynamic range, then LED flicker mitigation becomes difficult when exposure time is decreased
Solution Approach 1:
The multi-blade aperture stop provides dynamic control over aperture size, enabling the system to adjust the diameter to suit different exposure time requirements. This dynamic adjustment resolves the contradiction by allowing large aperture diameters when long exposure times are used for LED flicker mitigation
3Ease of manufacture
If the blades are made with smooth surfaces, then manufacturing is easier, but flaring occurs in captured images
Solution Approach 1:
The blade surfaces are treated with protrusions formed by corrosion treatment to create locally rough surfaces. This local quality change prevents flaring by scattering stray light, while the overall blade structure remains simple for manufacturing. The protrusions are specifically located on the light-facing surfaces of the blades
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 solution enables precise adjustment of exposure time and light amount, effectively mitigating LED flicker and flaring, thereby improving image quality and dynamic range in automotive cameras across different lighting conditions.
Implementation Method 1
a magnet and a coil disposed on at least one portion of the driving ring in a circumferential direction
Implementation Method 2
protrusions disposed on an internal surface of the through hole forming the incident hole
Data Source
AI summary
An aperture stop includes a housing, a blades disposed in the housing and rotated to form an incident hole having variable sizes, and a driver to rotatably move the blades. Each of the blades includes a through hole and protrusions disposed on an internal surface of the through hole forming the incident hole.