Color Sensor Pixel Layout for Crosstalk Suppression
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Solution Overview
Problem
Existing color sensors experience degradation in detection accuracy due to crosstalk in photoelectric conversion elements, which affects the accurate identification of light components under various illuminating conditions.
Innovation Solution
The color sensor is designed with a specific arrangement of pixels on a silicon substrate, where pixels detecting long-wavelength light are positioned on the outer side of the sensor unit, allowing crosstalk charges to be easily discharged outside, and impurities are introduced to reduce specific resistance and enhance charge diffusion, thereby suppressing crosstalk and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixels are arranged in a conventional layout on the silicon substrate, then the sensor achieves standard detection capability, but crosstalk occurs between adjacent pixels degrading detection accuracy
Solution Approach 1:
The patent applies asymmetry by positioning the long-wavelength detection pixel (red pixel) at the outer edge of the sensor array rather than in the center. This asymmetric arrangement exploits the fact that long-wavelength light generates charges that diffuse more easily, and by placing this pixel at the edge, the diffused charges are discharged outside the sensor area rather than interfering with adjacent pixels. This resolves the crosstalk problem while maintaining detection accuracy.
Solution Approach 2:
The patent converts the harmful effect of charge diffusion (which causes crosstalk) into a beneficial feature. Instead of trying to prevent charge diffusion, the invention utilizes it by strategically positioning the red pixel at the outer edge where diffused charges can be discharged usefully. The harmful crosstalk effect is transformed into a mechanism that actually improves detection accuracy by allowing controlled charge discharge.
2Adaptability or versatility
If multiple color filters are used to detect different wavelength bands, then light component detection capability is enhanced, but the complexity of the sensor structure increases
Solution Approach 1:
The patent applies multi-functionality by using a single pixel structure that can detect multiple wavelength bands through different color filters. The same photodetection element serves multiple purposes by detecting red, green, and blue light components, reducing the need for separate detection systems for each wavelength band while maintaining comprehensive spectral coverage.
Solution Approach 2:
The patent applies local quality by assigning different color filters to different pixels based on their specific detection requirements. Each pixel is optimized for particular wavelength bands through selective filter placement, with the red pixel at the edge and green/blue pixels in the center, creating locally optimized detection zones that collectively provide comprehensive wavelength coverage.
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 reduces the impact of crosstalk, allowing for higher accuracy in detecting light components and improving the identification of light sources, even under diverse illuminating conditions.
Implementation Method 1
The first photodiode 85 is a photoelectric conversion element that photoelectrically converts light incident through the first color filter 81
Implementation Method 2
impurities are included in the silicon substrate, and the impurities decrease specific resistance of the silicon substrate compared to the case where the impurities are not included
Data Source
AI summary
A pixel that detects short-wavelength light is provided in a light receiving unit on a silicon substrate and has a first color filter. A pixel that detects long-wavelength light is provided in the light receiving unit on the silicon substrate, is provided in a position closer to an outer edge of the light receiving unit than the pixel that detects the short-wavelength light, and has a second color filter. A longest-wavelength transmission band of the first color filter is a first transmission band, and the longest-wavelength transmission band of the second color filter is a second transmission band. The second transmission band has a longer wavelength than the first transmission band.