Electro-Optic Display Color Filter Arrays for Texture Reduction

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Solution Overview

Problem

Existing color filter arrays (CFAs) in electro-optic displays produce undesirable visible texture patterns due to differences in luminance contrast among the filter elements, which are particularly noticeable in white or light neutral gray colors, affecting image quality and rendering.

Innovation Solution

A color filter array design with subpixels of matched lightness, achieved by adjusting the ink concentrations of the filter elements using Kubelka-Munk modeling to equalize luminance or lightness among the primaries, reducing luminance contrast to minimize visible texture patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional color filter arrays are used in electro-optic displays, then color display functionality is achieved, but visible texture patterns appear due to luminance contrast differences among filter elements

Engineering Contradiction:

Improvecolor display functionalityVSAvoidvisible texture patterns

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by adjusting the ink concentrations of the color filter elements to equalize their luminance values. By modifying the concentration parameter of the filter inks, the luminance contrast among different color filters is reduced, thereby minimizing visible texture patterns while preserving color display functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by applying different ink concentrations to different color filter elements based on their specific luminance requirements. Each color filter element receives a tailored ink concentration to achieve uniform luminance across the array, rather than applying a uniform concentration to all elements

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If resolution is increased to reduce visible texture patterns, then image quality improves, but manufacturing costs and device complexity increase

Engineering Contradiction:

Improvevisible texture patternsVSAvoiddisplay resolution

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent resolves this contradiction by changing the luminance parameter of the color filter elements through ink concentration adjustment. This allows the existing resolution to effectively reduce visible texture patterns without requiring an increase in display resolution, thereby avoiding increased device complexity and manufacturing costs

Inventive Principle:

Principle #35Parameter changes

3Reliability

If luminance contrast among color filter elements is high, then color saturation is improved, but visible texture patterns become more noticeable

Engineering Contradiction:

Improvecolor saturationVSAvoidvisible texture patterns

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the ink concentration parameter to achieve an optimal balance. The luminance values are equalized across color filter elements to minimize texture visibility, while the color saturation is maintained through careful selection of ink types and concentrations that preserve chromaticity while adjusting luminance

Inventive Principle:

Principle #35Parameter changes

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 reduces the visibility of texture patterns by minimizing luminance differences between filter elements, improving image rendering and reducing costs compared to increasing resolution or modifying CFA patterns, while maintaining or enhancing color gamut volume.

Implementation Method 1

The color filter array comprises an array of pixels, each of which includes at least three color filter elements or subpixels. Each of the color filter elements has a different color... The colors of the color filter elements in the color filter array are configured to have the same lightness or a lightness difference no greater than 10 L*

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

The term 'electro-optic', as applied to a material or a display, is used herein in its conventional meaning in the imaging art to refer to a material having at least first and second display states differing in at least one optical property, the material being changed from its first to its second display state by application of an electric field to the material

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS20250284171A1Electro-optic displays with color filter arrays for reducing visible texture patterns in displayed images

Publication Date: 2025.09.11 E INK CORP

AI summary

A color electro-optic display includes a layer of electro-optic material having a light-transmissive electrode on a viewing side, an array of pixel electrodes on an opposite side, and a color filter array (CFA) on the viewing side. The pixel electrodes drive selected portions of the electro-optic material between white and black optical states. The CFA includes an array of pixels, each of which has at least three color filter elements. Each color filter element is aligned with a different one of the pixel electrodes such that the color of any color filter element is visible when the adjacent portion of the electro-optic material is driven to the white optical state, and not visible when driven to the black optical state. The colors of the color filter elements have the same lightness or a lightness difference no greater than 10 L* to substantially eliminate visible CFA texture patterns in displayed images.