Lighting Unit Stopper Design for Thermal Stress Dispersion

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Solution Overview

Problem

Conventional lighting units for liquid crystal displays face challenges in effectively fixing the light guide plate, which can lead to damage due to thermal expansion and external impacts, compromising the structural reliability of the lighting device.

Innovation Solution

A lighting unit design featuring a support substrate with a stopper system that includes a first stopper passing through a through hole in the printed circuit board and a second stopper fixed to a bent substrate portion, allowing for stable support of the light guide plate and dispersion of thermal expansion stress, thereby preventing cracks in the light package or printed circuit board.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the light guide plate is fixed using a conventional fixing unit, then the light guide plate can be held in position, but the light guide plate may still separate due to thermal expansion or external impact, causing damage to other components

Engineering Contradiction:
Improvestructural reliabilityVSAvoidthermal expansion damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stopper is designed with a cushioning structure that absorbs and distributes the stress generated by thermal expansion of the light guide plate before it can transmit to the printed circuit board or light package. The stopper acts as a buffer element that prevents direct force transmission, thereby protecting other components from damage while maintaining the light guide plate in a fixed position.

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

2Stability of the object's composition

If the light guide plate is rigidly fixed to prevent movement, then positioning stability is improved, but stress concentration occurs during thermal expansion, leading to cracks in the printed circuit board or light package

Engineering Contradiction:
Improvepositioning stabilityVSAvoidstress resistance
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The stopper serves as an intermediary element between the light guide plate and the printed circuit board. It provides positioning stability by preventing excessive movement of the light guide plate, while simultaneously acting as a stress-relieving mediator that distributes thermal expansion forces, preventing stress concentration and crack formation in the printed circuit board or light package.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If multiple stoppers are used to support the light guide plate in various directions, then stress distribution during thermal expansion is improved, but the device complexity increases

Engineering Contradiction:
Improvestress dispersion capabilityVSAvoidstopper configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fixing structure is segmented into multiple stoppers positioned at different locations and orientations around the light guide plate. Each stopper independently supports the light guide plate in specific directions, collectively providing comprehensive stress distribution capability during thermal expansion. This segmentation approach achieves reliable multi-directional support while maintaining modular simplicity in the design and manufacturing process.

Inventive Principle:
Principle #1Segmentation

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 structural reliability of the lighting unit by ensuring the light guide plate is stably supported, preventing damage from thermal expansion and external impacts, and reducing the risk of cracks in the light package or printed circuit board.

Implementation Method 1

stress generated due to thermal expansion of the light guide plate

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2818901B1Lighting unit
Publication Date: 2018.12.26 LG INNOTEK CO LTD
  • EP2818901B1 patent drawingFigure 1
  • EP2818901B1 patent drawingFigure 2
  • EP2818901B1 patent drawingFigure 3

AI summary

Provided is a lighting unit, including: a support substrate (140); a light guide plate (200) for guiding light generated from a light source (121); and a first stopper (130) fixed to the support substrate (140) and configured to support the light guide plate (200).