Circuit Board Protective Member for LED Thermal Expansion

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Solution Overview

Problem

The challenge is to prevent damage to light emitting diodes (LEDs) in backlight units of liquid crystal displays (LCDs) from thermal expansion of the light guide plate while maintaining the slimness and miniaturization of the backlight unit.

Innovation Solution

A circuit board design that includes a support substrate with a protective member connecting part, which stabilizes the protective member between light emitting device mounting parts, preventing rotation and damage from thermal expansion of the light guide plate, and features a protective member that protrudes beyond the light emitting device to secure it in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the LED and the light guide plate are disposed to be close to each other to achieve slimness and miniaturization, then the backlight unit size is reduced, but the LED is damaged upon thermal expansion of the light guide plate

Engineering Contradiction:
Improvebacklight unit sizeVSAvoidLED protection from thermal expansion
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

A protective member is introduced as an intermediary element positioned between the light guide plate and the LED. This protective member absorbs or accommodates the thermal expansion of the light guide plate, preventing direct contact and damage to the LED while allowing the LED and light guide plate to remain in close proximity for slimness.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective member is pre-positioned between the light guide plate and LED to provide cushioning before thermal expansion occurs. This beforehand cushioning prevents damage by absorbing expansion forces, allowing the backlight unit to maintain compact dimensions while protecting the LED from thermal stress.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If a protective member is added to prevent LED damage from thermal expansion, then LED protection is improved, but the device complexity increases

Engineering Contradiction:
ImproveLED protection from thermal expansionVSAvoidbacklight unit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective member is implemented as a thin film or flexible structure that can accommodate thermal expansion while maintaining a compact profile. This thin-film approach provides the necessary protection function without significantly increasing the overall device complexity or volume.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The protective member serves as a simple intermediary element that mediates between the thermally expanding light guide plate and the sensitive LED. By positioning this single protective component, the solution achieves LED protection with minimal additional structural complexity.

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 prevents LED damage from thermal expansion of the light guide plate, ensuring the backlight unit's slimness and miniaturization are maintained, and securely positions the protective member to prevent rotation and ensure stability.

Implementation Method 1

The LED is a light emitting device which generates light using a light emitting phenomenon generated at the time of applying a voltage to a semiconductor

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

it is problematic in that the LED is damaged upon thermal expansion of the light guide plate

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2755458B1Circuit board and flat panel display including the same
Publication Date: 2018.09.12 LG INNOTEK CO LTD
  • EP2755458B1 patent drawingFigure 1A~1B
  • EP2755458B1 patent drawingFigure 1C~2A
  • EP2755458B1 patent drawingFigure 2B~2C

AI summary

Provided are a circuit board for irradiating light to a light guide plate and a flat panel display having a structure for efficiently fixing the circuit board and the light guide plate, the circuit board, including: a support substrate (10) comprising a first area and a second area, the second area being bent from the first area; a plurality of light emitting device mounting parts (30) disposed in the first area; and a protective member connecting part of an outer side of the plurality of light emitting device mounting parts (30).