Light Reflecting Structures for LCD Backlight Uniformity

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Solution Overview

Problem

Side edge backlight modules in LCD displays suffer from Hotspot phenomenon due to non-uniform luminance caused by emitting angles of LEDs, leading to dark regions and increased power consumption, and high power LEDs generate heat causing the light guide plate to expand and potentially melt.

Innovation Solution

Incorporating light reflecting structures between sub light sources on a backplane, formed from transparent heat-contractible materials with refractivity between 1.4 and 1.8, and a reflecting film layer with diffusion particles, which are designed to reflect light uniformly and maintain a gap from the light guide plate to prevent contact and melting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a large number of LEDs are used to satisfy luminance uniformity requirement, then the Hotspot phenomenon is improved, but the power consumption and cost of the backlight module will be increased

Engineering Contradiction:
Improveluminance uniformityVSAvoidpower consumption
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The light source is divided into multiple sub light sources arranged in a line, with light reflecting structures positioned between them. This segmentation allows each LED to operate at lower power while the reflected light from adjacent structures compensates for luminance deficiencies, resolving the contradiction between using many low-power LEDs versus fewer high-power LEDs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Light reflecting structures are introduced as intermediary elements between the LEDs and the light guide plate. These structures reflect light from each sub light source into the light guide plate, improving luminance uniformity without requiring increased LED power consumption.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Use of energy by moving object

If high power LEDs are used to decrease the number of LEDs, then the power consumption is reduced, but heat is generated causing the light guide plate to expand and potentially melt

Engineering Contradiction:
Improvepower consumptionVSAvoidheat generation
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The light reflecting structures serve as thermal barriers between the LEDs and the light guide plate. By positioning these structures between the light sources and the plate, heat from high-power LEDs is blocked from directly contacting the light guide plate, preventing thermal expansion and melting while allowing the use of fewer, more efficient high-power LEDs.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If the light guide plate is positioned close to the LEDs for compact design, then the size is reduced, but the light guide plate is apt to be in contact with the LEDs causing melting

Engineering Contradiction:
Improvebacklight module sizeVSAvoidthermal stability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

Light reflecting structures are positioned between the LEDs and the light guide plate, serving as thermal barriers that prevent direct contact between the light source and the plate. This allows the backlight module to maintain a compact design while preventing heat transfer that would cause the light guide plate to melt.

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 significantly improves luminance uniformity, reduces power consumption, and prevents the light guide plate from melting by maintaining a gap and ensuring uniform light distribution, thereby enhancing the display quality and stability of the backlight module.

Implementation Method 1

the light reflecting structures are configured to reflect the light radiating thereon from the sub light sources into the light-emitting direction of the light-emitting unit

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

formed from transparent heat-contractible materials with refractivity between 1.4 and 1.8

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP2728248B1Light-emitting unit, backlight module and display device
Publication Date: 2021.12.08 BOE TECHNOLOGY GROUP CO LTD
  • EP2728248B1 patent drawingFigure 1~3(b)

AI summary

The invention discloses a light-emitting unit, comprising a backplane and a light source provided on the backplane. The light source includes a plurality of sub light sources. The light-emitting unit further comprises light reflecting structures provided between the sub light sources. The light reflecting structures are configured to reflect the light radiating thereon from the sub light sources into the light-emitting direction of the light-emitting unit. Accordingly, the invention discloses a backlight module including the light-emitting unit and a display device including the backlight module. The backlight module in the invention is not only capable of improving a Hotspot phenomenon, but also capable of preventing the light source in the light-emitting unit from directly contacting with a light guide plate.