Image Sensor Transmissive Pattern Refractive Index Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Refractive index variations between color filters and microlenses in image sensing devices lead to undesired refraction and reduced light energy, resulting in decreased sensitivity of pixel cells.
Innovation Solution
The implementation of a transmissive pattern with a microlens portion and a color filter portion formed over the color filter portion, where the absolute difference in refractive indices between the microlens and the color pattern is less than 0.3, and no difference in refractive indices between the microlens and color filter portions, to minimize refraction and enhance light energy transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If microlenses are formed over color filters with different refractive indices, then light focusing capability is improved, but undesired refraction occurs at the interface between microlenses and color filters
Solution Approach 1:
A transmissive pattern with refractive index matching (difference less than 0.3) is introduced as an intermediary layer between the microlens and color filter. This intermediary structure eliminates undesired refraction at the interface while preserving the light focusing capability of the microlens, thereby preventing light energy loss.
Solution Approach 2:
The refractive index parameter of the transmissive pattern is specifically designed to match that of the color filter (difference less than 0.3). By changing and controlling this physical parameter, the optical interface between microlens and color filter is optimized to eliminate refraction and energy loss.
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 approach reduces energy loss from incident light, thereby improving the sensitivity of pixel cells by minimizing refractive index variations and maintaining consistent refractive indices within the transmissive pattern.
Implementation Method 1
A plurality of microlenses of a square or a circular shape can be optionally superimposed over the color filter array (CFA) to focus light onto one initial charge accumulation region of each of the pixel cells
Implementation Method 2
a color pattern disposed over one of the photo-sensing elements, wherein the color pattern has a color selected from the group consisting of red (R), green (G), and blue (B)
Data Source
AI summary
An image sensing device includes: an active layer with a plurality of photo-sensing elements; a color pattern disposed over one of the photo-sensing elements, wherein the color pattern has a color selected from the group consisting of red (R), green (G), and blue (B); a microlens disposed on the color pattern; and a transmissive pattern being adjacent to the color pattern and over another one of the photo-sensing elements, wherein the transmissive pattern includes a color filter portion and a microlens portion, and an absolute value of a difference of refractive indexes between the microlens and the color pattern is less than 0.3, and there is no difference of refractive indexes between the microlens portion and the color filter portion of the transmissive pattern.