Color Filter Array Crosstalk Compensation

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Solution Overview

Problem

Crosstalk between pixels in image sensors leads to deterioration in color reproducibility, as existing color correcting circuits amplify noise and limit signal-to-noise ratio (SNR) due to high integration and reduced pixel size.

Innovation Solution

A color filter array with a primary green filter pixel and secondary yellow and cyan filter pixels, where the yellow and cyan filter pixels are diagonally aligned, and each pixel has compensated color spectral characteristics to minimize crosstalk, along with micro-lenses for light gathering and photo-sensing devices for converting light into electric signals, enhancing sensitivity and color reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high integration and reduced pixel size are used in image sensors, then productivity and integration are improved, but crosstalk between pixels increases and color reproducibility deteriorates

Engineering Contradiction:

ImproveintegrationVSAvoidcolor reproducibility

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by assigning different spectral characteristics to different pixels based on their location and function. Specifically, green filter pixels use a first spectral characteristic while yellow and cyan filter pixels use a second spectral characteristic. This localized differentiation allows each pixel type to optimize its light sensing properties, reducing crosstalk effects while maintaining high integration density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the spectral parameter of the color filters to resolve the contradiction. By adjusting the spectral characteristics of the green, yellow, and cyan filters according to specific formulas that consider the pixel area ratio and spectral sensitivity, the system achieves reduced crosstalk while maintaining high integration. The spectral parameters are specifically tuned to minimize interference between adjacent pixels of different colors.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional color correcting circuits are used for crosstalk compensation, then color reproducibility is improved, but noise is amplified and signal-to-noise ratio deteriorates

Engineering Contradiction:

Improvecolor reproducibilityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the conventional mechanical/electrical color correcting circuit approach with an optical solution. Instead of using post-processing circuits to compensate for crosstalk, the invention incorporates crosstalk compensation directly into the optical design of the color filters. The spectral characteristics of the filters are designed to inherently minimize crosstalk, eliminating the need for noise-prone electronic correction circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If pixel size is reduced for high integration, then productivity is improved, but light gathering capability decreases and sensitivity is reduced

Engineering Contradiction:

ImproveintegrationVSAvoidsensitivity

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses a composite color filter structure with multiple layers having different spectral characteristics. The green filter layer, yellow filter layer, and cyan filter layer are combined in a specific configuration where each layer contributes to the overall light gathering capability. This composite structure allows efficient utilization of the available light spectrum even in reduced pixel sizes, maintaining sensitivity while achieving high integration.

Inventive Principle:

Principle #40Composite materials

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 effectively compensates for crosstalk effects by adjusting the spectral characteristics of the color filters, resulting in improved color reproducibility and sensitivity, while maintaining signal integrity and reducing noise amplification.

Implementation Method 1

micro-lenses for gathering light

Methodology Applied

Scientific EffectLight gathering: Lens

Implementation Method 2

color filters are used for passing light frequencies in predetermined ranges to the photo sensing devices

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

photo sensing devices for converting light into electric signals

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS8054352B2Color filter array with reduced crosstalk effect and image sensor and image pickup apparatus having the same

Publication Date: 2011.11.08 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a color filter array including a primary color pixel such as a green filter pixel for sensing a predetermined primary color, a first secondary color pixel such as a yellow filter pixel, and a second secondary color pixel such as a cyan filter pixel. The primary color pixel, the first secondary color pixel, and the second secondary color pixel form different area ratios in the color filter array. For example, the area ratio of the yellow filter pixel to the cyan filter pixel and the green filter pixel is 2:1:1 in the color filter array. In addition, the color filters of the pixels are compensated for crosstalk effect. Such an image sensor has enhanced color reproducibility and sensitivity.