Bi-silicate Matrix Coating for Display Adhesion

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Solution Overview

Problem

Graphite-based matrix compositions in color displays exhibit weak adhesion to glass and internal strength issues, leading to adhesive failure during assembly of field emission devices.

Innovation Solution

Aqueous composition of graphite, potassium silicate, and sodium silicate is used to form a graphite-based matrix with improved adhesion, where potassium silicate hardens at room temperature and sodium silicate hardens during baking, ensuring strong adherence to the glass and within the coating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a graphite-based matrix composition is used to provide contrast between phosphors, then the display screen achieves proper visual contrast, but the matrix exhibits weak adhesion to glass and weak internal strength causing adhesive failure

Engineering Contradiction:

Improveadhesion strengthVSAvoidinternal strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent uses a composite material system combining graphite particles with a dual-silicate binder (potassium silicate and sodium silicate). The graphite provides contrast while the silicate matrix provides both adhesion to glass and internal cohesion. This composite approach allows simultaneous achievement of visual contrast function and mechanical strength requirements.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the binder system by using a specific ratio of potassium silicate to sodium silicate. Potassium silicate provides initial green strength and adhesion, while sodium silicate enhances internal cohesion and high-temperature stability. By adjusting these compositional parameters, the matrix achieves both required adhesion strength and internal strength.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If spacers are placed in contact with the graphite-based matrix during assembly, then the display device can be assembled, but adhesive failure occurs at the coating/glass interface causing spacers to fall over

Engineering Contradiction:

Improveassembly processVSAvoidcoating adhesion

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies the silicate binder system before spacer placement, allowing the binder to harden and create a strong adhesive interface between the graphite matrix and glass substrate. This preliminary bonding action ensures that when spacers are subsequently placed during assembly, the matrix coating remains firmly attached to the glass, preventing spacer failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The silicate binder acts as an intermediary material between the graphite particles and the glass substrate. It chemically bonds to both surfaces, creating a strong interface that transfers mechanical loads effectively. This intermediary layer prevents direct contact failures between spacers and the graphite-glass interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If adhesive failure occurs within the body of the graphite-based matrix composition, then the matrix comes away from the display screen, but proper contrast display is compromised

Engineering Contradiction:

Improvematrix cohesionVSAvoidcoating integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The dual-silicate composite binder system provides both adhesive bonding (to glass) and cohesive strength (within the matrix body). The combination of potassium silicate and sodium silicate creates a unified matrix structure where internal bonds are as strong as external bonds, preventing delamination and maintaining coating integrity throughout the display screen.

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 provides a graphite-based matrix with enhanced adhesive strength and internal cohesion, preventing failure at the glass/coating interface and within the coating, thus improving the reliability of color display screens.

Implementation Method 1

Potassium silicate hardens at room temperature and provides the graphite-based matrix composition with enough strength to survive subsequent processing steps

Methodology Applied

Scientific EffectHardening: Phase Change

Implementation Method 2

Sodium silicate hardens during baking (e.g., at 450° C.) so there is good adherence at the coating/glass interface and within the body of the coating during subsequent processing steps

Methodology Applied

Scientific EffectHardening: Phase Change

Implementation Method 3

The graphite-based matrix is formed from an aqueous composition including graphite, potassium silicate and sodium silicate

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS8138664B2Bi-silicate matrix coating for a display

Publication Date: 2012.03.20 INTERDIGITAL MADISON PATENT HLDG

AI summary

A display screen of a color display is disclosed (see FIG. 1). The display screen includes a glass plate having an array of three different color-emitting phosphors thereon. A graphite-based matrix is placed in the interstitial regions between each of the three different color-emitting phosphors. The graphite-based matrix is formed from an aqueous composition including graphite, potassium silicate and sodium silicate.