Dichroic Filter Array for Image Sensor Sensitivity and Noise
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Solution Overview
Problem
The Bayer pattern color filter array suffers from sensitivity loss and noise issues due to the use of infrared light for enhanced sensitivity, which is not effectively addressed by existing technologies.
Innovation Solution
A color filter array incorporating a dichroic filter with varying thickness regions, made of titanium dioxide and silicon dioxide layers, is used to selectively filter specific wavelength ranges, allowing visible and infrared light to pass through color and transparent pixels respectively, while blocking unwanted wavelengths to improve image sensitivity and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transparent pixel is substituted for one of RGB pixels to pass light and infrared light, then image sensitivity is improved, but noise is introduced due to infrared light components incident on color pixels
Solution Approach 1:
The patent divides the pixel array into different types of pixels (first pixels and second pixels) with different filtering characteristics. The first pixels are configured to pass visible light while blocking infrared light, while the second pixels pass both visible light and infrared light. This segmentation allows the system to capture both color information and infrared information without introducing noise, as each pixel type is optimized for its specific function.
Solution Approach 2:
Different regions of the pixel array are assigned different optical properties. The first pixels have optical characteristics optimized for visible light capture, while the second pixels have optical characteristics optimized for infrared light capture. This local differentiation of quality allows the system to simultaneously achieve high sensitivity for both visible and infrared light without the harmful effects of infrared noise in color pixel regions.
2Ease of manufacture
If a Bayer pattern color filter array is used to represent primary colors, then color information is captured without processing, but sensitivity is lost
Solution Approach 1:
The patent creates a multi-functional pixel system where pixels can be configured to perform multiple functions. Some pixels are designed to capture visible light for color information, while others are designed to capture infrared light for enhanced sensitivity. This universality allows the system to maintain the simplicity of the Bayer pattern for color capture while adding infrared capability for improved sensitivity without requiring complex processing.
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
The solution enhances image sensitivity and resolution while minimizing noise by selectively passing and blocking light wavelengths, thereby improving the overall image quality captured by the image sensor.
Implementation Method 1
a dichroic filter corresponding to the plurality of pixels, the dichroic filter being formed either above or below the pixel layer
Implementation Method 2
the dichroic filter is configured to filter a specific wavelength range of light that is to be incident to the plurality of pixels or that has passed through the plurality of pixels, according to the plurality of thicknesses of the plurality of regions corresponding to the plurality of pixels
Implementation Method 3
the dichroic filter comprises a layered structure in which a layer of titanium dioxide (TiO2) and a layer of silicon dioxide (SiO2) are repeatedly formed
Implementation Method 4
the dichroic filter comprises a layered structure in which a layer of titanium dioxide (TiO2) and a layer of silicon dioxide (SiO2) are repeatedly formed
Data Source
AI summary
A color filter array may include a plurality of pixels and control a pass wavelength band of the plurality of pixels using a dichroic filter that passes light of a specific wavelength range and blocks the rest of wavelengths. The pass wavelength band of the plurality of pixels may be adjusted according to a plurality of thicknesses of the dichroic filter. The dichroic filter may be formed by repeatedly forming a layer of titanium dioxide (TiO2) and a layer of silicon dioxide (SiO2).