Imaging Device White Filter Refractive Index Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In solid-state imaging devices, the reduction in pixel size leads to lowered sensitivity, and the use of white pixels with refractive index differences from color filters results in optical color mixing, compromising color reproduction properties.
Innovation Solution
The implementation of a solid-state imaging device with a specific refractive index relationship between white filters, microlenses, and planarizing films, where the white filter's refractive index is greater than or equal to the microlens' and greater than the planarizing film's, and the use of materials like copolymer resin with metallic compounds to form white filters that match the refractive indices of color filters, preventing light leakage between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If white filters with different refractive index from color filters are used in W pixels, then sensitivity is enhanced by permitting transmission of light in the whole visible spectral range, but optical color mixing occurs between adjacent pixels
Solution Approach 1:
The patent changes the refractive index parameter of the white filter material to match or exceed the refractive index of adjacent color filters. This parameter modification eliminates the refractive index difference that causes light deflection and optical color mixing, while maintaining the white filter's ability to transmit light across the visible spectrum.
Solution Approach 2:
The patent creates homogeneity in the optical properties by ensuring that the white filter has a refractive index matching the color filters. This homogeneous refractive index across different filter types prevents light from being deflected at filter boundaries, thereby preventing optical color mixing between adjacent pixels of different types.
2Measurement precision
If pixel size is reduced to increase the number of pixels, then resolution is improved, but sensitivity characteristic per pixel is lowered
Solution Approach 1:
The patent introduces W pixels that can receive light across the entire visible spectrum, making them multi-functional in terms of spectral response. This allows the imaging device to maintain high sensitivity in smaller pixel formats by utilizing pixels that efficiently capture all wavelengths, compensating for the reduced light-gathering area of each individual pixel.
3Use of energy by moving object
If white filter material does not contain pigment or dye, then light transmission in whole visible spectral range is achieved, but refractive index difference from color filters causes light deflection
Solution Approach 1:
The patent modifies the refractive index parameter of the white filter material by selecting materials such as resins or polymers with refractive indices of 1.50 or higher, matching or exceeding that of the color filters. This parameter change ensures that light paths remain straight and undeviated when passing through or between different filter types, eliminating the light deflection problem.
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 optical color mixing and enhances color reproduction properties by ensuring light is refracted correctly within its intended pixel, improving sensitivity and image quality.
Implementation Method 1
a microlens 16 is formed on the white filter 15W and the color filter 15G... the refractive indices of the white filter, the microlens and the planarizing film are in the following relationship
Implementation Method 2
white filters not containing a pigment or dye as an R, G or B color component are formed in place of existing color filters to thereby form W pixels
Implementation Method 3
a planarizing film 14 is formed thereon... formed on the planarizing film 14, a white filter 15W is formed in the region of each W pixel 1W
Data Source
AI summary
A solid-state imaging device including a plurality of pixels arranged two-dimensionally, wherein each of the pixels has at least a planarizing film formed on the upper side of a photoelectric conversion element, a filter formed on the upper side of the planarizing film, and a microlens formed on the upper side of the filter. The filter of some of the pixels is a color filter permitting transmission therethrough of light of a predetermined color component, whereas the filter of other pixels is a white filter permitting transmission therethrough of light in the whole visible spectral range. The refractive indices of the white filter, the microlens and the planarizing film have the following relationship: (Refractive index of white filter)≧(Refractive index of microlens)>(Refractive index of planarizing film).