Estimating Electrical Cross Talk in Color Image Sensors
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Solution Overview
Problem
Current methods lack an efficient way to estimate electrical cross talk in color solid-state image sensors, which causes color-shifting issues due to lateral diffusion of electrons, especially in small pixel arrays, leading to poor performance and failed products.
Innovation Solution
A method involving a flow chart process to acquire electrical information from imaging cells, extract cross talk coefficients using a matrix representation, and generate an estimated color spectral response by applying these coefficients to a theoretical response, effectively quantifying directional cross talk and predicting sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the pitch between imaging cells is reduced to increase pixel density, then the imaging resolution is improved, but the electrical cross talk increases causing color-shifting problems
Solution Approach 1:
The patent introduces an intermediary measurement system (laser scanning apparatus with MTF characterization) that acts as a mediator between the imaging cells and the cross-talk analysis. This intermediary enables indirect measurement of cross-talk effects through modulation transfer function characterization, allowing quantification of the harmful electrical cross-talk without directly observing the electron diffusion process itself.
Solution Approach 2:
The patent replaces direct electrical measurement methods with optical measurement methods. Instead of using electrical probes to measure cross-talk, the invention uses laser scanning and optical MTF measurement techniques to characterize the cross-talk effects, substituting mechanical/electrical measurement systems with optical fields for non-contact characterization.
2Ease of operation
If conventional MTF measurement methods are used to characterize cross talk, then the measurement process is simplified, but the ability to quantify directional cross talk and predict performance is insufficient
Solution Approach 1:
The patent segments the cross-talk measurement process into distinct components: (1) MTF characterization through laser scanning, (2) extraction of cross-talk coefficients from MTF data, and (3) directional analysis of cross-talk. This segmentation allows the complex measurement task to be broken down into manageable steps while maintaining both ease of operation and measurement precision.
Solution Approach 2:
The patent performs partial measurement by focusing on specific directional components of cross-talk rather than attempting to measure all possible interactions simultaneously. By measuring MTF at specific orientations and extracting directional coefficients, the method achieves precise quantification of dominant cross-talk directions without the excessive complexity of complete characterization.
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 method allows for accurate quantification and prediction of cross talk, improving the performance of color solid-state image sensors by reducing color-shifting errors and enhancing design modifications.
Implementation Method 1
When exposed to light, the photons which pass through the color filter are absorbed by the imaging cells which, in turn, generate electron-hole pairs
Implementation Method 2
Some of the photogenerated electrons can diffuse laterally a few cells, usually not more than two, before being collected by an adjacent imaging cell
Data Source
AI summary
The electrical cross talk in color solid-state image sensor is estimated or characterized by acquiring image data from an array of imaging cells which is a portion of a much larger array, extracting cross talk data from the acquired image data, and characterizing the cross talk based on the extracted coefficients.