Backlight Unit Light Shielding Patterns for Uniform Luminance

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Solution Overview

Problem

Backlight units suffer from non-uniform luminance due to hotspots, which affect the display quality.

Innovation Solution

The implementation of light shielding patterns in the backlight unit, comprising a first light shielding film and a reflection film, strategically positioned to reduce brightness at light emission surfaces and adjacent regions, ensuring uniform light distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If light sources are used to illuminate the LCD panel, then the display is powered, but hot spots occur causing non-uniform luminance

Engineering Contradiction:
Improveluminance uniformityVSAvoidhot spots
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by positioning light shielding patterns at specific locations corresponding to light sources. These patterns have different properties (light blocking) only in the regions where hot spots occur, while allowing uniform light transmission in other areas. This localized intervention corrects the luminance non-uniformity without affecting the overall illumination effectiveness.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The light shielding patterns serve as an intermediary element between the light sources and the LCD panel. They mediate the light transmission by selectively blocking excessive light in hot spot regions while allowing sufficient light to reach the display area, thus achieving uniform luminance distribution without eliminating the light sources themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If light shielding patterns are added to prevent hot spots, then luminance uniformity is improved, but device complexity increases

Engineering Contradiction:
Improveluminance uniformityVSAvoidbacklight unit structure
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges the light shielding function with existing backlight unit components. The light shielding patterns are integrated into the backlight structure, combining multiple functions (light transmission, light shielding, and hot spot prevention) into a unified system. This reduces the need for separate components and minimizes structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent achieves luminance uniformity by changing the optical parameters (light transmission characteristics) of specific regions through the light shielding patterns. By adjusting the light blocking properties in hot spot areas, the overall luminance distribution is optimized without fundamentally altering the backlight unit's structural parameters or requiring complex mechanical modifications.

Inventive Principle:
Principle #35Parameter changes

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 light shielding patterns effectively prevent hotspots, resulting in a uniform luminance across the display, enhancing the overall display quality and reducing manufacturing costs.

Implementation Method 1

a reflection film, strategically positioned to reduce brightness at light emission surfaces

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

a first light shielding film and a reflection film, strategically positioned to reduce brightness

Methodology Applied
Scientific EffectLight absorption/shielding: Absorption (EM radiation)

Data Source

PatentEP2558905B1Backlight unit and display apparatus comprising the same
Publication Date: 2015.09.09 LG ELECTRONICS INC
  • EP2558905B1 patent drawingFigure 1~3
  • EP2558905B1 patent drawingFigure 4~8
  • EP2558905B1 patent drawingFigure 9~11

AI summary

A backlight unit is provided that comprises a first layer, a plurality of light sources on the first layer, a reflection layer on the first layer, the reflection layer surrounding the plurality of light sources, a second layer on the reflection layer and the plurality of light sources, and a third layer on the second layer, the third layer comprising a plurality of light shielding patterns arranged to correspond to the light sources, respectively, and a light transmitting region surrounding the plurality of light shielding patterns, wherein the light transmitting region includes first regions adjacent to the light sources and second regions away from the light sources, and wherein the first regions are smaller in area than the second regions. A display apparatus comprising the backlight unit is provided as well.