Fluorescent Color Filter for LCD Luminance

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Solution Overview

Problem

Conventional liquid crystal displays (LCDs) suffer from significant light loss due to the absorption of white light by color filters, which limits luminance and efficiency, and require additional light sources or increased driving voltage to compensate for this loss.

Innovation Solution

Incorporating a fluorescent color filter on the first substrate that absorbs ultraviolet rays to emit visible light, reducing light loss and increasing luminance, and using an intra-cell polarizer to manage light polarization within the LCD.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a traditional color filter is used to absorb white light, then color display is achieved, but light loss increases and luminance decreases

Engineering Contradiction:

ImproveluminanceVSAvoidlight loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent changes the working principle of the color filter from light absorption to light emission through fluorescence. By using fluorescent materials that absorb UV light and emit visible light in specific wavelengths, the system transforms the parameter of light interaction from subtractive (absorption) to additive (emission), thereby improving luminance and reducing light loss.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional optical absorption mechanism with a photoluminescence mechanism. Instead of using dyes or pigments that absorb specific wavelengths, the system uses fluorescent materials that convert UV energy to visible light, substituting one physical mechanism for another more efficient one.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Illumination intensity

If fluorescent material is coated in the backlight unit to generate visible light, then luminance improves, but fabrication complexity and cost increase

Engineering Contradiction:

ImproveluminanceVSAvoidfabrication cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent merges the functions of the color filter and the fluorescent light generation into a single component. By integrating the fluorescent material directly into the color filter structure, the system eliminates the need for separate fluorescent coatings in the backlight unit, thereby simplifying the manufacturing process and reducing costs while maintaining high luminance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The color filter is designed to serve multiple functions: it acts as both the color selection element and the fluorescent light source. This multi-functionality eliminates the need for separate components in the backlight unit, simplifying the overall structure and reducing fabrication complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Use of energy by moving object

If light condensing films are added to improve light directionality, then light efficiency improves, but device complexity and fabrication cost increase

Engineering Contradiction:

Improvelight efficiencyVSAvoidstructure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the need for light condensing films by designing the fluorescent color filter to emit light in the desired direction inherently. The fluorescent material's emission characteristics and the filter structure are configured to provide the necessary light directionality without requiring additional optical films, thereby reducing device complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

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 enhances light efficiency and luminance by over 50% compared to traditional LCDs, while reducing fabrication costs by eliminating the need for internal fluorescent material in the backlight unit and light condensing films.

Implementation Method 1

a fluorescent color filter responding to light over the first substrate, thereby the fluorescent color filter supplies the light to the liquid crystal layer

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

an intra-cell polarizer formed on the fluorescent color filter

Methodology Applied

Scientific EffectPolarization: Polarisation

Data Source

PatentUS7777838B2Liquid crystal display device and fabrication method thereof

Publication Date: 2010.08.17 LG DISPLAY CO LTD

AI summary

A liquid crystal display (LCD) comprises: a first substrate and a second substrate; a liquid crystal layer between the first and the second substrates; and a fluorescent color filter responding to light over the first substrate, thereby the fluorescent color filter supplies the light to the liquid crystal layer. A method for fabricating a LCD includes: preparing first and second substrates; depositing fluorescent material over the first substrate to form a color filter, the fluorescent material emitting the visible light in responding to the ULTRAVIOLET rays; and forming a liquid crystal layer between the first and second substrates.