Color Filter Substrate with Varying Thickness for LCD Brightness Uniformity

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Solution Overview

Problem

LCD display devices experience brightness failures at edge regions due to uneven electric fields, alignment issues in alignment layers, and asymmetric storage capacitance, leading to non-uniform brightness across the panel.

Innovation Solution

A color filter substrate with color filter layers of varying thicknesses is fabricated using a halftone mask to adjust light transmittance, with thicker layers at edge regions to reduce light passing through and improve brightness uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If color filter layers are made with uniform thickness, then manufacturing is simple, but brightness uniformity deteriorates at edge regions

Engineering Contradiction:

Improvecolor filter layer fabricationVSAvoidbrightness uniformity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The color filter layer is designed with different thicknesses for different regions: a first thickness for edge regions and a second thickness for non-edge regions. This local variation in thickness compensates for the brightness failure at edge regions while maintaining uniform brightness across the entire display panel.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If color filter layer thickness is increased at edge regions, then brightness uniformity improves, but manufacturing complexity increases

Engineering Contradiction:

Improvebrightness uniformityVSAvoidcolor filter layer structure

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The thickness parameter of the color filter layer is changed based on position: edge regions have a first thickness while non-edge regions have a second thickness. This parameter variation resolves the brightness non-uniformity issue without requiring complex additional structures.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If halftone mask process is used to create varying thickness, then brightness uniformity improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvebrightness uniformityVSAvoidhalftone mask alignment

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

A halftone mask is introduced as an intermediary tool during the photolithography process to create the varying thickness profile of the color filter layer. The mask's optical properties enable precise thickness control at different regions through controlled light exposure.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 decreases light transmission at edge regions, preventing brightness failures and enhancing picture quality by ensuring uniform brightness across the LCD panel.

Implementation Method 1

A color filter substrate with color filter layers of varying thicknesses is fabricated using a halftone mask to adjust light transmittance

Methodology Applied

Scientific EffectLight transmittance adjustment: Absorption (EM radiation)

Data Source

PatentUS8173334B2Color filter substrate and method of fabricating the same

Publication Date: 2012.05.08 LG DISPLAY CO LTD

AI summary

A color filter substrate includes a first color filter layer on a substrate, and a second color filter layer on the substrate, the first color filter layer having a thickness different from a thickness of the second color filter layer.