Movable LED Module for LCD Thermal Expansion Gap Control

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Solution Overview

Problem

In liquid crystal displays (LCDs), the gap between the light guide plate and the light emitting diode (LED) is not uniformly maintained due to thermal expansion of the light guide plate, leading to potential collisions and reduced efficiency in light distribution.

Innovation Solution

The implementation of a movable LED module with elastic members and contact members that allow the LED module to adjust relative to the light guide plate during thermal expansion, ensuring a consistent gap is maintained through the use of a printed circuit board and contact members coupled to the bottom chassis, allowing the light guide plate to press on the contact members rather than the LEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the light guide plate is made close to the LED to increase brightness, then illumination intensity is improved, but thermal expansion causes collision between the light guide plate and LED

Engineering Contradiction:
ImprovebrightnessVSAvoidcollision prevention
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The LED module is designed to be movable relative to the light guide plate through an elastic supporting structure. The LED module can move in the direction of thermal expansion of the light guide plate, transforming from a static fixed structure to a dynamic adjustable structure that adapts to thermal changes while maintaining close proximity for high brightness

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The gap distance between the LED and light guide plate is made variable rather than fixed. The elastic member allows the gap to change dynamically in response to thermal expansion, enabling the system to maintain optimal brightness while preventing collision through parameter adaptation

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a safety gap is maintained between the light guide plate and LED to prevent collision, then reliability is improved, but brightness is reduced due to increased distance

Engineering Contradiction:
Improvecollision preventionVSAvoidbrightness
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

Instead of maintaining a fixed safety gap, the system uses a dynamic gap that adjusts with thermal expansion. The elastic supporting structure allows the LED module to move, enabling the gap to be small under normal conditions for high brightness while automatically increasing during thermal expansion for collision prevention

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The elastic member automatically adjusts the LED module position in response to thermal expansion forces from the light guide plate. The system self-regulates the safety gap without external intervention, maintaining optimal brightness while preventing collision through automatic adaptation

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If the LED module is made movable to accommodate thermal expansion, then adaptability is improved, but device complexity increases due to additional components

Engineering Contradiction:
Improvethermal expansion accommodationVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The elastic member acts as a flexible component that provides the necessary movement capability. This flexible element enables thermal expansion accommodation with minimal structural complexity, avoiding the need for complex mechanical adjustment mechanisms while maintaining adaptability

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The elastic member serves as an intermediary between the fixed light guide plate and the movable LED module. This simple intermediary component enables relative movement and thermal expansion accommodation without requiring complex control systems or multiple moving parts

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

This solution prevents collisions between the light guide plate and LEDs during thermal expansion, enabling a closer arrangement for increased brightness while reducing power consumption at the same brightness level compared to conventional LCD structures.

Implementation Method 1

the light guide plate undergoes thermal expansion

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

an elastic member arranged to elastically support the LED module

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2722707B1Liquid crystal display
Publication Date: 2019.12.04 SAMSUNG ELECTRONICS CO LTD
  • EP2722707B1 patent drawingFigure 1
  • EP2722707B1 patent drawingFigure 2
  • EP2722707B1 patent drawingFigure 3

AI summary

A LED module includes a printed circuit board, LEDs which are vertically mounted on the printed circuit board and which emit light onto a side surface, and a contact member which is provided to come into contact with a light guide plate. The printed circuit board may be movably coupled to a bottom chassis. When the light guide plate undergoes thermal expansion, the LED module may move by pressing of the light guide plate acting on the contact member. Accordingly, a gap between the light guide plate and the LEDs may be uniformly maintained even when the light guide plate undergoes thermal expansion or is returned to an original state.