CMOS Image Sensor Pixel Layout for Sensitivity Uniformity
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Solution Overview
Problem
Conventional image pickup elements experience sensitivity differences between pixels of the same color, leading to potential image quality degradation due to alignment of pixels in vertical or horizontal directions.
Innovation Solution
The implementation of a multi-spectrum image pickup apparatus with a CMOS image sensor and a plasmon filter having a hole array structure, which includes a narrow band filter layer with a transmission band set for each pixel, and a color filter layer to reduce flare and sensitivity differences by adjusting the transmission band and filter configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixels of the same color are arranged in units of blocks of two rows and two columns, then high resolution and color moire reduction are achieved, but sensitivity difference between pixels of the same color increases
Solution Approach 1:
The patent applies asymmetry by arranging pixels of the same color in asymmetric positions within each 2x2 block. Specifically, in green pixel blocks, one green pixel is positioned at the center while another is offset, and similar asymmetric arrangements are applied to other color blocks. This asymmetric positioning within blocks ensures that pixels of the same color do not align in straight lines, thereby reducing sensitivity differences while maintaining the high-resolution benefits of the mosaic arrangement.
2Ease of manufacture
If pixels are aligned in vertical or horizontal directions, then manufacturing and reading are simplified, but sensitivity difference between pixels of the same color increases
Solution Approach 1:
The patent segments the pixel array into multiple 2x2 blocks, where each block contains pixels of different colors arranged in a mosaic pattern. Within each block, pixels are positioned at different relative locations rather than being uniformly aligned. This segmentation approach maintains the simplicity of block-based manufacturing while preventing straight-line alignment of same-color pixels across the entire array, thus reducing sensitivity differences.
3Measurement precision
If narrow band filter is used for each pixel, then light detection precision is improved, but flare and sensitivity differences between pixels increase
Solution Approach 1:
The patent applies local quality by assigning different transmission bands to narrow band filters in different pixels. Each pixel's narrow band filter is configured with a specific transmission band tailored to its position and color, optimizing light detection for that local region while managing flare effects. This localized optimization allows precise light detection in each pixel while the varied transmission bands prevent uniform flare patterns across the array.
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 configuration effectively suppresses sensitivity differences between pixels, enhancing image quality and reducing flare, allowing for improved light detection and image capture across various applications.
Implementation Method 1
an image pickup element that detects light of a predetermined narrow wavelength band (narrow band) by using a plasmon filter
Implementation Method 2
includes a photodiode which performs photoelectric conversion
Data Source
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AI summary
The present technology relates to an image pickup element and an electronic device that can suppress a difference in sensitivity of light receiving units. The image pickup element includes a pixel array in which at least a first light receiving unit that receives light in a predetermined color and a second light receiving unit that receives light having a wavelength band of a band width narrower than a wavelength band of the predetermined color are arranged and, in a case where the pixel array is divided into four areas by a vertical line and a horizontal line, a position of the second light receiving unit in a first block, in which one or more of each of the first light receiving unit and the second light receiving unit are arranged, differs in each of the areas. The present technology can be applied to, for example, a CMOS image sensor.