Image Sensor Panchromatic Pixel Array Light Sensitivity
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Solution Overview
Problem
Existing electronic image sensors with two-dimensional arrays of pixels face reduced light sensitivity due to the use of color filters, limiting their ability to capture images in low-light conditions or with short exposure times, especially in handheld devices or those capturing moving objects.
Innovation Solution
The development of an image sensor with a two-dimensional array of both color and panchromatic pixels, where panchromatic pixels have a wider spectral sensitivity, allowing for improved light sensitivity and the ability to capture full-color images effectively in low-light conditions by intermixing pixels with and without color filters, and combining signals from these pixels to enhance overall sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are applied to pixels to enable color image capture, then color sensitivity is improved, but light sensitivity is reduced
Solution Approach 1:
The pixel array is segmented into multiple types of pixels including color-filtered pixels (with red, green, or blue filters) and panchromatic pixels (without color filters). This segmentation allows different regions of the sensor to serve different functions: color pixels provide chromatic information while panchromatic pixels maximize light capture efficiency, resolving the contradiction between color sensitivity and light sensitivity.
Solution Approach 2:
Different pixels within the same array are assigned different spectral sensitivities based on their local function. Color-filtered pixels have narrow spectral response for accurate color discrimination, while panchromatic pixels have broad spectral response for maximum light sensitivity. This local differentiation of quality allows the system to achieve both color accuracy and high light sensitivity simultaneously.
2Measurement precision
If two-dimensional sensor arrays are used for image capture, then spatial resolution is improved, but light sensitivity is reduced compared to linear sensors
Solution Approach 1:
The two-dimensional array is segmented into functional groups including color pixels and panchromatic pixels. By distributing panchromatic pixels throughout the array rather than concentrating them in separate regions, the design maintains the spatial resolution benefits of two-dimensional sensing while improving overall light sensitivity through the inclusion of filterless pixels.
3Illumination intensity
If all pixels are made panchromatic to maximize light sensitivity, then light sensitivity is improved, but color accuracy is reduced
Solution Approach 1:
Rather than making all pixels panchromatic, the array is segmented into a mixture of color-filtered pixels and panchromatic pixels. The color-filtered pixels (with red, green, or blue filters) provide accurate chromatic information, while the panchromatic pixels contribute to overall light sensitivity. This segmentation resolves the contradiction by assigning different spectral sensitivities to different pixels based on their functional role.
Solution Approach 2:
Each pixel is assigned a specific spectral sensitivity profile appropriate to its local function. Color pixels have filtered spectral response for accurate color discrimination, while panchromatic pixels have unfiltered broad spectral response for maximum light capture. This local quality differentiation allows the system to achieve both color accuracy and high light sensitivity.
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 significantly enhances the light sensitivity of image sensors, enabling effective image capture in low-light conditions and reducing noise, thereby improving the signal-to-noise ratio and allowing for faster image scanning without the need for mechanical motion or additional complex components.
Implementation Method 1
an image sensor with a two-dimensional array of color and panchromatic pixels... panchromatic pixels have a wider spectral sensitivity
Data Source
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AI summary
An image sensor for capturing a color image is disclosed having a two-dimensional array having first and second groups of pixels wherein pixels from the first group of pixels have narrower spectral photoresponses than pixels from the second group of pixels and wherein the first group of pixels has individual pixels that have spectral photoresponses that correspond to a set of at least two colors, with the placement of the first and second groups of pixels defining a pattern that has a minimal repeating unit including at least six pixels with at least some rows or columns of the minimal repeating unit composed only of pixels from the second group of pixels, and including ways to combine similarly positioned pixels from at least two adjacent minimal repeating units.