Image Sensor Pixel Array with Mixed Luminance Sensitivity
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Solution Overview
Problem
Conventional image sensors with uniform pixel saturation levels struggle to optimize image quality under varying luminance conditions, leading to issues like white spot phenomena and dark current, especially in low-luminance environments where saturation levels are not critical but noise is.
Innovation Solution
An image sensor with a pixel array comprising low-luminance and high-luminance pixels, where low-luminance pixels accumulate less charge and high-luminance pixels accumulate more, are alternately arranged to adjust signal weighting based on calculated luminance, allowing for improved color interpolation and higher signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform pixel saturation levels are used in conventional image sensors, then manufacturing is simplified, but image quality deteriorates in low-luminance conditions due to white spot phenomena and dark current
Solution Approach 1:
The patent applies local quality by creating different types of pixels (first pixels with lower saturation and second pixels with higher saturation) within the same pixel array. Each pixel type is optimized for specific luminance conditions, allowing the sensor to maintain high image quality across varying light conditions while using standard fabrication processes.
Solution Approach 2:
The patent changes the saturation level parameter of pixels based on their intended function. First pixels have a first saturation level optimized for low-luminance conditions, while second pixels have a second saturation level optimized for high-luminance conditions. This parameter differentiation resolves the contradiction between manufacturing simplicity and image quality.
2Power
If pixels with high saturation levels are used, then signal strength is improved in bright conditions, but white spot phenomena and dark current increase in low-luminance conditions
Solution Approach 1:
Different regions of the pixel array have pixels with different saturation characteristics. Second pixels with high saturation are distributed to capture strong signals in bright conditions, while first pixels with lower saturation are used where white spot phenomena would occur, thus eliminating harmful effects while maintaining signal strength where needed.
Solution Approach 2:
The pixel array is segmented into functionally different pixel types. First pixels and second pixels are spatially distributed throughout the array, allowing the system to selectively use appropriate pixel types based on local luminance conditions, thereby managing signal strength and harmful effects locally.
3Object-generated harmful factors
If pixels with low saturation levels are used, then white spot phenomena are reduced, but signal-to-noise ratio decreases in high-luminance conditions
Solution Approach 1:
The patent uses first pixels with lower saturation in regions where white spot phenomena would occur, and second pixels with higher saturation in regions where strong signal capture is needed. This local optimization ensures that white spot phenomena are suppressed where necessary while maintaining high signal-to-noise ratio where light is abundant.
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 image quality by prioritizing signal weighting from low-luminance pixels in low-luminance conditions and high-luminance pixels in bright conditions, resulting in a higher signal-to-noise ratio and better image representation.
Implementation Method 1
at least one low-luminance pixel that comprising a first photoelectric conversion device that accumulates a charge corresponding to a first charge value
Implementation Method 2
at least one high-luminance pixel that comprising a second photoelectric conversion device that accumulates a charge corresponding to a second charge value
Data Source
AI summary
An image sensor, an image processing apparatus including the same and an interpolation method of the image processing apparatus are provided. The image sensor includes a plurality of pixels that include a low-luminance pixel including a first photoelectric conversion device that accumulates a charge less than a predetermined reference value and a high-luminance pixel including a second photoelectric conversion device that accumulates a charge more than the predetermined reference value. Interpolation is carried out giving more weight to the low-luminance pixel at low luminance and giving more weight to the high-luminance pixel at high luminance, so that a higher SNR is obtained.