Image Sensor White and Color Pixels for Luminance Accuracy
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Solution Overview
Problem
Color image sensors using MOS technology face challenges in low light conditions due to light attenuation by color filters and interference from near-infrared radiation, which affects luminance and chrominance accuracy.
Innovation Solution
The use of a matrix of active photosensitive pixels with colored and white pixels, where the photodiodes of colored pixels are designed to be less sensitive to infrared wavelengths than those of white pixels, allowing for improved luminance information in low light conditions without the need for additional filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are deposited on all pixels to capture color information, then chroma information is improved, but luminance sensitivity in low light conditions deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of specific pixel regions. White pixels are left without color filters to maximize light collection for luminance, while colored pixels retain filters for chroma. This spatial differentiation of optical characteristics resolves the contradiction between chroma accuracy and luminance sensitivity.
Solution Approach 2:
The pixel array is segmented into distinct functional zones: white pixels dedicated to luminance capture and colored pixels dedicated to chroma capture. This segmentation allows each region to optimize its performance for its specific function, thereby resolving the trade-off between luminance and chroma performance.
2Ease of manufacture
If organic pigment filters are used to reduce cost, then manufacturing cost is reduced, but near-infrared radiation interference increases
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of specific pixel regions. White pixels are left without color filters to maximize light collection for luminance, while colored pixels retain filters for chroma. This spatial differentiation of optical characteristics resolves the contradiction between chroma accuracy and luminance sensitivity.
Solution Approach 2:
The patent extracts the infrared-sensitive pixels (white pixels) from the colored pixel population. By separating infrared-sensitive measurements from color-filtered measurements, the system can process infrared information independently or discard it, thereby removing the harmful interference from colorimetric accuracy while maintaining the cost benefits of organic filters.
3Object-affected harmful factors
If a global infrared filter is added to block near-infrared radiation, then infrared interference is reduced, but luminance information quality deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of specific pixel regions. White pixels are left without color filters to maximize light collection for luminance, while colored pixels retain filters for chroma. This spatial differentiation of optical characteristics resolves the contradiction between chroma accuracy and luminance sensitivity.
Solution Approach 2:
The pixel array is segmented into distinct functional zones: white pixels dedicated to luminance capture and colored pixels dedicated to chroma capture. This segmentation allows each region to optimize its performance for its specific function, thereby resolving the trade-off between luminance and chroma performance.
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 quality of luminance information in low light conditions while minimizing the impact of infrared radiation, providing a more accurate representation of the scene without the cost and luminance reduction associated with global infrared filters.
Implementation Method 1
each pixel comprising a silicon photodiode to supply an electric signal depending on the electric charges generated in the photodiode by the light
Implementation Method 2
a mosaic of filters of different colors... The filters are made from colored pigments in organic matter... the transmission curve of the filter as a function of frequency is not rectangular but rather Gaussian
Data Source
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AI summary
The invention concerns colour image sensors. In order to benefit both from good brightness resolution and a colorimetry that is not excessively degraded by the sensitivity of silicon to near infrared radiation, the invention proposes producing a pixel mosaic comprising colour pixels (R), (G), (B), coated with colour filters, distributed in the matrix, with white pixels (T) not coated with colour filters and distributed in the matrix. The colour pixels comprise photodiodes constituted differently to the photodiodes of the white pixels, the different constitution being such that the photodiodes of the colour pixels have a lower sensitivity to infrared radiation than the photodiodes of the white pixels.