EL Sheet Insert Molding for Shock and Water Resistance

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Solution Overview

Problem

Existing light-emitting devices with EL sheets assembled via insert molding are prone to damage from external shocks and water exposure, leading to potential short circuits and reduced luminance due to the thinness and exposure of the EL sheets.

Innovation Solution

The EL sheet is assembled with a fixing body and a molded body through insert molding, where the EL sheet is held in place by a holder, preventing external damage and water ingress, and the feeder terminal is exposed for easy connection while maintaining water resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the EL sheet is plastically deformed to a bent shape in advance, then the EL sheet can be assembled in a curved configuration, but the electrode layer may be damaged at bent corners causing nonluminescent portions

Engineering Contradiction:

Improvecurved configuration of EL sheetVSAvoidintegrity of electrode layer

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The holder is prepared in advance with positioning protrusions that match the curved configuration needed. The EL sheet is placed on the holder before injection molding, allowing it to be pre-positioned in the desired curved shape without requiring plastic deformation that could damage the electrode layer.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The holder acts as an intermediary between the EL sheet and the final molded structure. It provides mechanical support and positioning during the assembly process, enabling the thin EL sheet to maintain its curved configuration without self-deformation that would risk electrode damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the EL sheet is exposed on the outer surface of the light-emitting device, then the structure is simpler, but light-emitting elements deteriorate due to absorbed water and luminance decreases

Engineering Contradiction:

Improvestructural simplicityVSAvoidwater resistance of EL sheet

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The molded body forms a protective shell that encloses the EL sheet. This shell structure provides water resistance and environmental protection while maintaining relative structural simplicity through the injection molding process that creates an integrated enclosure.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The EL sheet is nested within the holder, which is in turn enclosed by the molded body. This nested arrangement protects the sensitive EL sheet from water and environmental factors while maintaining a compact and relatively simple overall structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Length of moving object

If the EL sheet is very thin to reduce device thickness, then the device becomes more compact, but the EL sheet becomes weak against external shocks and abrupt bending forces

Engineering Contradiction:

Improvethickness of deviceVSAvoidresistance to external shocks

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The holder and molded body structure provide protective cushioning around the thin EL sheet before external shocks can reach it. The injection-molded resin material absorbs and distributes impact forces, protecting the fragile EL sheet while maintaining the overall thin profile of the device.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The device combines the thin EL sheet with the holder structure and injection-molded resin body, creating a composite construction. The EL sheet provides the light-emitting function while the surrounding structures provide mechanical strength and shock resistance, achieving both thinness and durability.

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 enhances the durability and water resistance of the light-emitting device, preventing damage to the EL sheet and maintaining its luminance, while providing a better appearance by shielding it from the external environment.

Implementation Method 1

a molded body disposed on another surface of the EL sheet, the molded body being injection-molded in covering relation to the EL sheet held on the fixing body to integrally combine the fixing body and the EL sheet with the molded body according to insert molding

Methodology Applied

Scientific EffectInsert molding:

Implementation Method 2

The adhesive of the adhesive layer is melted with the heat of the injected resin to bond the EL sheet to the resin

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS7604363B2Light-emitting device

Publication Date: 2009.10.20 TOYO DENSO CO LTD

AI summary

A light-emitting device includes EL sheets assembled according to insert molding, a fixing body disposed on rear surfaces of the EL sheets and having a groove and holes for holding the EL sheets prior to being assembled according to insert molding in a desired position, and a molded body disposed on front surfaces of the EL sheets. The molded body is injection-molded in covering relation to the EL sheets held on the fixing body to integrally combine the fixing body and the EL sheet with the molded body according to insert molding.