Automotive Camera Light Intensity Adjustment via Polarizing Filters
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Solution Overview
Problem
Automotive cameras face challenges in accurately capturing light flashes from modern light sources like LEDs due to the stroboscopic effect, which occurs when the shutter timing does not align with the flash duration, leading to missed flashes and potential safety issues in varying lighting conditions.
Innovation Solution
An apparatus with adjustable linear polarizing filters and a grey filter is mounted on the automotive camera, allowing for adaptive light intensity control by moving the filters relative to each other or electronically dimming, maintaining integration time close to the frame period to prevent stroboscopic effects and ensure accurate light capture across different lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable integration time is used to adapt to different lighting conditions, then the image sensor can avoid overexposure in high light conditions, but it causes stroboscopic effect when capturing pulsed light sources like LEDs
Solution Approach 1:
The patent replaces the mechanical shutter system with an optical solution using polarizing filters. Instead of mechanically controlling the shutter timing to match LED pulse duration, the invention uses at least one linear polarizing filter and at least one circular polarizing filter in combination with a quarter-wave plate to optically adjust light intensity. This substitution eliminates the stroboscopic effect caused by mechanical shutter timing while maintaining accurate capture of pulsed light sources.
Solution Approach 2:
The patent changes the optical parameters by introducing polarizing filters and a quarter-wave plate into the optical path. By rotating the linear polarizing filter relative to the circular polarizing filter, the system dynamically adjusts the polarization state and intensity of light reaching the sensor. This parameter change allows the sensor to capture pulsed LED light accurately without being affected by shutter timing, as the optical filters modulate light intensity independently of the mechanical shutter cycle.
2Adaptability or versatility
If mechanical stop mechanisms are used to control light intensity, then the camera can adapt to varying lighting conditions, but the device becomes complex and bulky
Solution Approach 1:
The patent replaces complex mechanical stop mechanisms with a simpler optical system based on polarizing filters. Instead of using movable mechanical stops to control aperture and light intensity, the invention employs at least one linear polarizing filter and at least one circular polarizing filter that can be rotated independently. This substitution dramatically reduces mechanical complexity while maintaining the ability to adapt to varying lighting conditions through optical polarization control.
Solution Approach 2:
The patent introduces dynamic control through independent rotation of the linear and circular polarizing filters. Rather than relying on complex mechanical stop movements, the system dynamically adjusts light intensity by rotating the polarizing filters to different angular positions. This dynamic optical control achieves light intensity adaptation with simpler, more reliable moving parts compared to traditional mechanical stop mechanisms.
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 effectively prevents stroboscopic effects, ensuring that light flashes are captured consistently, enhancing driver safety by maintaining accurate image brightness and reliability in various lighting conditions without the need for complex or bulky mechanical stop mechanisms.
Implementation Method 1
The apparatus comprises at least one linear polarizing filter, at least one circular polarizing filter and at least one quarter wave plate, arranged in front of a lens unit such that incident light passes through the at least one linear polarizing filter, the at least one circular polarizing filter and the at least one quarter wave plate before entering the lens unit
Data Source
AI summary
An apparatus for light intensity adjustment mountable on an automotive camera includes at least one first linear polarizing filter, at least one second linear polarizing filter, the first linear polarizing filter and the second polarizing filter are arrangeable in front of a lens unit of an automotive camera such that incident light passes through the at least one first linear polarizing filter and the at least one second linear polarizing filter before entering the lens unit of the automotive camera, and at least one actuator for moving the at least one first linear polarizing filter and/or the at least one second linear polarizing filter with respect to each other such that the intensity of the emergent light is adjustable. The apparatus is characterized in enabling adjustment of the emergent light intensity by moving the first linear polarizing filter and/or the second linear polarizing filter with respect to each other.