Color-Separating Lens Array for Infrared Crosstalk Reduction
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Solution Overview
Problem
Existing image sensors with silicon-based photoelectric conversion elements suffer from low infrared pixel signal conversion rates and crosstalk due to microlenses, hindering the improvement of image quality, especially in multi-spectral and 3D image sensors.
Innovation Solution
The use of a color separating lens array that separates and condenses infrared light efficiently by altering the phase of light wavelengths, combined with infrared and visible light filters, to enhance light utilization efficiency and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microlens is used in a silicon-based photoelectric conversion element, then visible light can be focused effectively, but infrared light crosstalk occurs and signal conversion rate decreases
Solution Approach 1:
The lens array is segmented into different types of microlenses: first microlenses corresponding to infrared pixels with larger focal lengths for infrared light, and second microlenses corresponding to visible light pixels with smaller focal lengths for visible light. This segmentation allows each microlens type to optimize for its specific wavelength range, preventing infrared crosstalk while maintaining visible light detection accuracy.
Solution Approach 2:
Different regions of the lens array have different microlens characteristics. The microlens focal length varies locally depending on the pixel type underneath - infrared pixels receive microlenses optimized for infrared wavelengths while visible light pixels receive microlenses optimized for visible wavelengths. This local quality differentiation resolves the contradiction by tailoring optical properties to specific functional requirements.
2Measurement precision
If the infrared pixel area is increased to improve signal conversion rate, then more infrared light can be detected, but visible light pixels area decreases reducing overall image quality
Solution Approach 1:
The system dynamically adapts optical parameters (microlens focal length) based on the underlying pixel type. By making the microlens properties variable rather than uniform, the system can optimize infrared detection in specific regions without permanently sacrificing visible light detection capability in other regions, effectively resolving the area allocation contradiction.
3Object-generated harmful factors
If a color filter is added to block infrared light from visible light pixels, then crosstalk is reduced, but light utilization efficiency decreases
Solution Approach 1:
Instead of using a color filter to block infrared light (which would waste energy), the solution extracts and separates infrared light detection to dedicated infrared pixels with specialized microlenses. This removes the harmful infrared crosstalk function from visible light pixels while preserving overall light utilization efficiency by directing infrared light to appropriate sensors rather than blocking it.
4Adaptability or versatility
If both infrared and visible light pixels are integrated in the same sensor, then multi-spectral and 3D imaging capability is achieved, but crosstalk and signal conversion issues arise
Solution Approach 1:
The pixel array is segmented into distinct infrared and visible light pixel regions, each with dedicated microlenses optimized for their wavelength range. This segmentation enables multi-spectral imaging capability while preventing crosstalk and maintaining high signal conversion rates for each pixel type by providing specialized optical paths.
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 improves light utilization efficiency and reduces crosstalk, leading to enhanced image quality and functionality in multi-spectral and 3D image sensors.
Implementation Method 1
The plurality of light condensing regions are configured to change the phase of the first wavelength light such that the first wavelength light passing through the plurality of light condensing regions may have a phase profile that reduces in a direction away from a center of the plurality of light condensing regions
Implementation Method 2
a color separating lens array capable of condensing infrared light separately
Implementation Method 3
an infrared filter disposed between the sensor substrate and the color separating lens array that face the plurality of first pixels in a vertical direction, the infrared filter being configured to block visible light
Implementation Method 4
a color filter disposed between the sensor substrate and the color separating lens array that face the plurality of second pixels in a vertical direction, the color filter being configured to block infrared ray
Data Source
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AI summary
Provided is an image sensor including a sensor substrate including a plurality of first pixels configured to sense first wavelength light in an infrared ray band and a plurality of second pixels configured to sense second wavelength light in a visible light band, and a color separating lens array disposed on the sensor substrate and configured to change a phase of the first wavelength light incident on the color separating lens array such that the first wavelength light is condensed to the plurality of first pixels, wherein the color separating lens array includes a plurality of light condensing regions configured to condense the first wavelength light respectively on the plurality of first pixels, and wherein an area of each of the plurality of light condensing regions is larger than an area of each of the plurality of first pixels.