FPC Fixing via Hot Mounting Pins to Prevent Mura

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Solution Overview

Problem

Existing methods for fixing flexible printed circuits (FPCs) in display modules face issues such as mura formation, reflector warping, and poor adhesion due to the use of fixing glue, especially in limited spaces, leading to compromised display performance.

Innovation Solution

A method involving a housing with fixing pins and corresponding holes in the FPC, where the FPC is folded back and secured using a hot mounting process to enlarge the fixing pins, eliminating the need for glue and allowing secure attachment without altering the reflector's size or shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fixing glue is used to adhere the FPC to the reflector, then the FPC can be fixed to the display module, but the reflector becomes warped and mura occurs on the display panel

Engineering Contradiction:

ImproveFPC fixation reliabilityVSAvoidreflector shape

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent removes the reflector from the FPC fixation process entirely. Instead of using the reflector as the fixation substrate, the invention uses the housing as the fixation base, extracting the harmful element (reflector) from the fixation chain and eliminating the source of warping and mura defects

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces the housing as an intermediary structure between the FPC and the display module. The housing serves as a stable fixation base that does not suffer from the same limitations as the reflector, allowing reliable FPC fixation without compromising display quality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the reflector size is reduced to allow fixing glue adhesion around it, then the FPC can be fixed without warping the reflector, but light leakage occurs from the back of the backlight module

Engineering Contradiction:

ImproveFPC fixation stabilityVSAvoidlight leakage

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent extracts the FPC fixation function from the reflector system entirely. By using the housing as the fixation substrate, the reflector can maintain its full size and proper shape without being compromised by fixation requirements, thereby preventing light leakage while achieving reliable FPC fixation

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If fixing glue with electric conductivity is used to fix the FPC, then the FPC can be electrically connected, but the adhesion is too poor causing peeling

Engineering Contradiction:

Improveelectrical connectionVSAvoidadhesion strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces the chemical adhesion mechanism (fixing glue) with a mechanical fixation system using fixing pins. This substitution eliminates the adhesion strength problem entirely, as mechanical interlocking through pins and holes provides superior and more reliable fixation compared to adhesive bonding

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces fixing pins as intermediary mechanical elements that provide both electrical connection and strong mechanical fixation. These pins serve dual functions: establishing electrical continuity between the FPC and housing while providing robust mechanical attachment that prevents peeling

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If the fixing glue adheres to the reflector in a narrow space, then the FPC can be fixed, but the reflector becomes warped after a period

Engineering Contradiction:

Improveinitial FPC fixationVSAvoidreflector stability over time

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent extracts the FPC fixation function from the reflector and relocates it to the housing. This separation allows the reflector to maintain its structural integrity over time without being subjected to the stresses of adhesive bonding, thereby ensuring long-term stability while achieving initial fixation reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a simple, replaceable fixing pin system instead of relying on the long-term stability of adhesive bonds. The mechanical fixation system provides immediate and reliable fixation without the degradation issues that affect adhesive bonds over time

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 method efficiently fixes the FPC without changing the reflector's size or shape, preventing mura and warping, and ensures reliable adhesion, maintaining display quality and reducing light leakage.

Implementation Method 1

performing a hot mounting process to the fixing pin to enlarge the top end of the fixing pin

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS7872701B2Method for fixing FPC of display

Publication Date: 2011.01.18 INNOCOM TECH (SHENZHEN) CO LTD

AI summary

A method for fixing a flexible circuit board (FPC) of a display module includes providing a housing having at least a fixing pin, providing a display panel and an FPC having at least a fixing hole corresponding to the fixing pin, disposing the display panel and the FPC on the housing and folding back the FPC on another side of the housing such that the fixing pin passes through the fixing hole, and performing a hot mounting process to the fixing pin to enlarge the top end of the fixing pin to press the FPC onto the housing.