Semiconductor Light Source Flicker Detection
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Solution Overview
Problem
Image capture devices face challenges in capturing high-quality images in environments with flickering ambient light, as the frequency of ambient light often goes out of sync with the rolling shutter exposure window, leading to artifacts like 'beating' row patterns and overexposure.
Innovation Solution
An image capture device is configured with a semiconductor light source that operates in both illumination and sensor modes to analyze the frequency of ambient light and adjust the rolling shutter exposure window to an integer multiple of the ambient light period, synchronizing exposure timing to prevent artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rolling shutter exposure window is used for image capture, then the device can capture images in various lighting conditions, but artifacts like 'beating' row patterns appear when ambient light frequency is out of sync with exposure timing
Solution Approach 1:
The patent dynamically adjusts the rolling shutter exposure window duration based on the detected ambient light frequency. The system continuously monitors the ambient light frequency and modifies the exposure timing accordingly, transforming a static exposure parameter into a dynamic one that adapts to changing lighting conditions, thereby preventing artifacts while maintaining versatility across different environments.
Solution Approach 2:
The patent changes the exposure window parameter (specifically its duration) to match integer multiples of the ambient light period. By adjusting this critical parameter based on detected frequency, the system ensures that the exposure timing synchronizes with the ambient light cycles, eliminating beating patterns while preserving the ability to capture images in diverse lighting scenarios.
2Illumination intensity
If the exposure window duration is increased to integrate more ambient light, then image brightness improves, but overexposure occurs in high illumination environments
Solution Approach 1:
The system dynamically adjusts the exposure window duration based on both ambient light frequency and intensity levels. In high illumination environments, the exposure duration is reduced to prevent overexposure, while in lower light conditions, it is increased to ensure sufficient brightness. This dynamic adaptation allows the system to optimize image brightness across varying illumination levels without causing overexposure.
Solution Approach 2:
The patent applies preliminary anti-action by detecting ambient light frequency and intensity before capturing the image, then pre-adjusting the exposure window parameters to prevent overexposure. The system proactively compensates for potential overexposure by modifying exposure timing in advance, based on the detected lighting conditions, thereby preventing the harmful effect before it occurs.
3Measurement precision
If the main CPU analyzes captured images to determine ambient light frequency, then frequency detection is achieved, but processing time increases and artifacts remain in the analyzed image
Solution Approach 1:
The patent performs frequency detection as a preliminary action before image capture, using a dedicated sensor to measure ambient light frequency in advance. This pre-detection allows the system to configure the exposure window parameters beforehand, eliminating the need for post-capture analysis and reducing processing time. The frequency information is obtained in advance to guide the exposure settings.
Solution Approach 2:
The patent introduces a dedicated ambient light sensor as an intermediary component between the light source and the main processing system. This sensor specifically measures the ambient light frequency and provides this information to the exposure control system, enabling accurate frequency detection without requiring the main CPU to analyze the captured image, thereby reducing processing time and avoiding artifacts in the final image.
4Measurement precision
If a separate ambient light sensor is added to detect frequency, then frequency detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent makes the semiconductor light source multi-functional by enabling it to operate in both illumination mode and sensor mode. When not providing illumination, the light source can detect ambient light frequency, eliminating the need for a separate dedicated sensor. This universal application of the existing component maintains frequency detection accuracy while avoiding increased device complexity.
Solution Approach 2:
The semiconductor light source serves itself by performing dual functions: illuminating the scene when needed and detecting ambient light frequency when not illuminating. This self-service capability allows the system to maintain accurate frequency detection without adding external components, as the existing light source component provides the sensing function in addition to its primary illumination role.
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 solution effectively eliminates image capture artifacts caused by flickering ambient light, ensuring consistent exposure and preventing overexposure, thereby improving image quality.
Implementation Method 1
a semiconductor light source that is configured to operate alternatively in an illumination mode as a light source and in a sensor mode as an ambient light sensor
Data Source
Figure 1~1A
Figure 2A~2B
Figure 3
AI summary
Devices and methods for adjusting an exposure window of a rolling shutter based on a frequency determined from ambient light gathered by a bimodal component are disclosed. Flickering light sources may cause artifacts in captured images, due to interplay between a period of a frequency of ambient light and the exposure window. An image capture device includes a semiconductor component configured to operate in two modes and an exposure window control component configured to compensate for the flickering based on a signal from the light source. In a sensor mode, the semiconductor component may operate to detect the frequency of ambient light. To avoid image artifacts, the frequency of the ambient light is analyzed and an exposure time is adjusted to an integer multiple of the period of the frequency such that exposure is matched to the periodic illumination of the flickering light source.