Image Sensor Pixel Groups with Neutral Density Filters
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Solution Overview
Problem
Conventional high dynamic range (HDR) image sensors often experience lower resolution, sensitivity, and higher noise levels, which limits their performance in capturing images across varying light conditions.
Innovation Solution
The implementation of pixel groups with attenuated and unattenuated pixels, where attenuated pixels receive neutral density filters and microlenses to redirect light to unattenuated pixels, enhancing the dynamic range by optimizing performance in both high and low light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional HDR image sensors use alternate rows of pixels with different integration times, then dynamic range is improved, but resolution and sensitivity decrease while noise levels increase
Solution Approach 1:
The pixel array is segmented into pixel groups, where each group contains multiple pixels with different optical characteristics (different integration times or neutral density filter densities). This segmentation allows each pixel within the group to capture different exposure levels simultaneously, resolving the contradiction by maintaining full spatial resolution while achieving HDR through intra-group diversity rather than inter-row differentiation.
Solution Approach 2:
Different pixels within the same pixel group are assigned different local optical properties (such as different neutral density filter densities or integration times). This local quality differentiation enables each pixel to be optimized for specific lighting conditions while maintaining the same spatial resolution across the entire array, thus improving dynamic range without sacrificing resolution or increasing noise.
2Adaptability or versatility
If conventional HDR image sensors use alternate rows of pixels with different integration times, then dynamic range is improved, but sensitivity decreases
Solution Approach 1:
The pixel array is segmented into pixel groups, where each group contains multiple pixels with different optical characteristics (different integration times or neutral density filter densities). This segmentation allows each pixel within the group to capture different exposure levels simultaneously, resolving the contradiction by maintaining full spatial resolution while achieving HDR through intra-group diversity rather than inter-row differentiation.
Solution Approach 2:
Different pixels within the same pixel group are assigned different local optical properties (such as different neutral density filter densities or integration times). This local quality differentiation enables each pixel to be optimized for specific lighting conditions while maintaining the same spatial resolution across the entire array, thus improving dynamic range without sacrificing resolution or increasing noise.
3Adaptability or versatility
If conventional HDR image sensors use alternate rows of pixels with different integration times, then dynamic range is improved, but noise levels increase
Solution Approach 1:
The pixel array is segmented into pixel groups, where each group contains multiple pixels with different optical characteristics (different integration times or neutral density filter densities). This segmentation allows each pixel within the group to capture different exposure levels simultaneously, resolving the contradiction by maintaining full spatial resolution while achieving HDR through intra-group diversity rather than inter-row differentiation.
Solution Approach 2:
Different pixels within the same pixel group are assigned different local optical properties (such as different neutral density filter densities or integration times). This local quality differentiation enables each pixel to be optimized for specific lighting conditions while maintaining the same spatial resolution across the entire array, thus improving dynamic range without sacrificing resolution or increasing noise.
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 improves the dynamic range of image sensors by allowing them to capture a wider range of light intensities, reducing noise, and maintaining sensitivity, thereby enhancing image quality across different lighting conditions.
Implementation Method 1
An imaging pixel may include a neutral density filter for attenuating light to the imaging pixel
Implementation Method 2
microlenses to redirect light to unattenuated pixels
Implementation Method 3
Typical image pixels contain a photodiode for generating charge in response to incident light
Data Source
AI summary
A high dynamic range image sensor may include a plurality of pixel groups. One or more pixel groups may include attenuated pixels in addition to unattenuated pixels. The unattenuated pixels may include a photosensitive area, a color filter element and a microlens of a first size. Each attenuated pixel may include a photosensitive area, a color filter element, a neutral density filter, and a microlens of a second size that is smaller than the first size. The color filter elements for each pixel in a given pixel group may be the same color. The neutral density filter may attenuate light for the attenuated pixels, increasing dynamic range of the image sensor. The microlenses of varying sizes may redirect light from attenuated pixels towards unattenuated pixels, further increasing the dynamic range.