Near-Infrared Cut Filter Pixel Array for Optical Sensor Noise Reduction
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Solution Overview
Problem
Existing optical sensors face challenges in detecting light with high sensitivity and low noise, particularly in ambient and infrared light conditions, due to noise interference in the near-infrared region.
Innovation Solution
A filter with two-dimensionally arranged pixels, including near-infrared cut filters that shield near-infrared light and transmit visible light, is used to enhance the signal-to-noise ratio (S/N ratio) in optical sensors, solid-state imaging elements, and image display devices. The filter features specific absorption wavelengths and refractive indices, along with combinations of near-infrared cut filters and infrared transmitting filters, to effectively manage light transmission and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a near-infrared cut filter is used to shield near-infrared light, then the signal-to-noise ratio is improved, but the filter complexity increases due to multiple pixel types
Solution Approach 1:
The filter is divided into multiple pixel types (first near-infrared cut filter pixels, second near-infrared cut filter pixels, and infrared transmitting filter pixels) arranged in a two-dimensional pattern. Each pixel type handles different wavelength ranges, allowing the system to reduce noise in specific bands while maintaining sensitivity in others, thus improving signal-to-noise ratio without requiring a completely complex filter structure
Solution Approach 2:
Different regions of the filter have different optical properties tailored to local needs. The first near-infrared cut filter pixels shield light in the 700-900nm range, the second near-infrared cut filter pixels shield light in the 900-1100nm range, and the infrared transmitting filter pixels transmit infrared light. This local differentiation allows each pixel type to optimize for its specific function, improving overall signal-to-noise ratio while keeping the total device complexity manageable through functional specialization
2Adaptability or versatility
If multiple types of pixels are arranged in the filter, then the light detection capability is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The filter array is segmented into distinct pixel types with specific wavelength filtering characteristics. The first near-infrared cut filter pixels, second near-infrared cut filter pixels, and infrared transmitting filter pixels are arranged in a two-dimensional pattern, allowing each segment to be optimized for its specific function while maintaining overall system versatility
Solution Approach 2:
The patent specifies precise parameter ranges to guide manufacturing: the absorbance ratio Amax/A550 is controlled at 20-500, the maximum absorption wavelength is set at 700-2000nm, and the height difference between pixel top surfaces is limited to 20% or less of the thickest pixel film thickness. These parameter specifications provide clear manufacturing targets that balance enhanced light detection capability with achievable manufacturing precision
3Measurement precision
If the height difference between pixel top surfaces is minimized, then the image quality is improved, but the manufacturing difficulty increases
Solution Approach 1:
The patent establishes a specific parameter constraint for the height difference between pixel top surfaces, limiting it to 20% or less of the film thickness of the thickest pixel. This quantitative specification provides a clear manufacturing target that balances image quality improvement with manufacturing feasibility, avoiding overly stringent requirements that would make production prohibitively difficult
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 proposed filter design enables the detection of light with reduced noise and improved sensitivity, achieving a higher S/N ratio and enabling clear image capture with minimal distortion, suitable for various applications including biometric and monitoring systems.
Implementation Method 1
a pixel of a near-infrared cut filter that shields at least a part of light having a wavelength in the near-infrared region and transmits light having a wavelength in the visible region
Implementation Method 2
A silicone photodiode having sensitivity to infrared rays has been used in a light-receiving unit of the solid-state imaging element
Data Source
AI summary
Provided are a filter capable of detecting light with less noise, an optical sensor, a solid-state imaging element, and an image display device. This filter is provided with a plurality of different pixels that are two-dimensionally arranged, and at least one of the plurality of pixels is a pixel 11 of a near-infrared cut filter that shields at least a part of light having a wavelength in the near-infrared region and transmits light having a wavelength in the visible region.