Image Sensor Polarizing Filters Auto White Balancing
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Solution Overview
Problem
Conventional auto white balancing methods in image sensors produce poor results when dealing with monochromatic images or multiple light sources, as they rely solely on input image data and assume a single dominant light source.
Innovation Solution
An image sensor system with a pixel array and a micro lens array, where each micro lens is juxtaposed with a group of pixels and equipped with polarizing filters having at least two different polarizing phases, generates polarized sub-images and uses a signal processor to conduct auto white balancing based on these sub-images, determining the light source characteristics and depth to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional auto white balancing method using statistical analysis of input image data is used, then the system is simple and easy to operate, but the auto white balancing accuracy deteriorates when dealing with monochromatic images or multiple light sources
Solution Approach 1:
The image sensor divides the imaging function into multiple specialized components: color filter array for color separation, micro lens array for light focusing, and polarizing filter array for polarization filtering. This segmentation allows each component to specialize in extracting specific light characteristics, thereby improving auto white balancing accuracy without requiring complex post-processing algorithms.
Solution Approach 2:
The patent introduces a new dimension of polarization information alongside traditional color information. By incorporating polarizing filters with different transmission axes, the system captures light properties in multiple dimensions (color + polarization), enabling more accurate light source characterization and auto white balancing performance.
2Measurement precision
If polarizing filters with multiple polarizing phases are added to each micro lens, then the auto white balancing accuracy improves by capturing light source characteristics, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges multiple functions into a single integrated sensor structure: color filtering, micro lens focusing, and polarization filtering are combined in a unified array configuration. This integration reduces the number of separate components and alignment steps, thereby improving manufacturability while maintaining the ability to capture comprehensive light characteristics.
Solution Approach 2:
Each pixel unit in the sensor array is designed to perform multiple functions simultaneously: capturing color information through the color filter array, focusing light via the micro lens, and filtering polarization through the polarizing filter array. This multi-functionality reduces the need for separate specialized components, simplifying the overall manufacturing process.
3Adaptability or versatility
If multiple polarizing filters are disposed on micro lenses, then the ability to handle multiple light sources and monochromatic images improves, but the loss of energy increases due to multiple filtering layers
Solution Approach 1:
The polarizing filters are configured to selectively filter light based on polarization direction rather than blocking all light. This partial filtering approach maintains adaptability to different lighting conditions by capturing polarization-specific information while minimizing overall light energy loss compared to complete blocking filters.
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 enhances the accuracy and reliability of auto white balancing, producing more realistic images even under varying light conditions or when multiple light sources are present.
Implementation Method 1
The image sensor may include a semiconductor device that transforms incident light into an electric signal (i.e., performs photoelectric transformation) to provide image information corresponding to the incident light.
Implementation Method 2
a micro lens array disposed on the pixel array and including a plurality of micro lenses and a plurality of polarizing filters, and in which each of the micro lenses is juxtaposed with a respective group of pixels of the pixel array
Implementation Method 3
polarizers optically aligned with the micro lenses such that light directed onto the pixels in the sensor by the micro lenses is polarized by the polarizers
Data Source
AI summary
An image sensor includes a pixel array, a micro lens array and polarizing filters. The pixel array includes a plurality of pixels. The micro lens array is disposed on the pixel array and includes a plurality of micro lenses. The micro lens overlaps a pixel group of the pixel array. The polarizing filter is disposed on the micro lens and includes a plurality of polarizing filters having at least two different polarizing phases. Accordingly, the accuracy and the reliability of the local auto white balancing may be improved.