Top-illumination LED Backlight Assembly with Vertical PCB

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Solution Overview

Problem

Conventional backlight assemblies for liquid crystal display (LCD) devices using side-illumination type LEDs suffer from reduced light efficiency and increased thickness due to different orientation angles and the placement of printed circuit boards, which also affect the stability and color reproducibility of the LEDs.

Innovation Solution

A backlight assembly design featuring a top-illumination type LED configuration with LEDs mounted on a vertically disposed printed circuit board, where each LED includes a blue chip and fluorescent substances to convert blue light into white light, with a lead frame structure that enhances mounting stability and uniform light distribution by having a larger lower portion than side portion, ensuring consistent orientation angles and reduced thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If side-illumination type LED is used to provide light to the light guide plate, then the LED can be mounted on the printed circuit board, but the different orientation angles along vertical and horizontal directions reduce light-using efficiency

Engineering Contradiction:

Improvelight-using efficiencyVSAvoidlight distribution uniformity

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent inverts the conventional side-illumination configuration by using top-illumination type LEDs that emit light perpendicular to the printed circuit board. This inversion allows the light to enter the light guide plate from the top surface, ensuring uniform orientation angles in all directions and improving both light-using efficiency and light distribution uniformity.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If the printed circuit board is disposed over or under the light guide plate, then the LED can be mounted, but the total thickness of the backlight assembly increases

Engineering Contradiction:

ImproveLED mounting capabilityVSAvoidbacklight assembly thickness

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The patent changes the spatial arrangement from a planar configuration (PCB disposed over or under the light guide plate) to a vertical configuration (PCB disposed at the side of the light guide plate with top-illumination LEDs). This dimensional change allows the light-emitting components to be positioned in a different spatial dimension, reducing the overall thickness of the backlight assembly while maintaining LED mounting capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If conventional LED mounting structure is used, then the LED can be fixed on the PCB, but the mounting stability is insufficient

Engineering Contradiction:

ImproveLED mounting stabilityVSAvoidmounting structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the LED mounting structure into distinct functional components: a dedicated mounting protrusion on the PCB for mechanical support, a recess on the LED package for engagement, and a soldering area for electrical connection. This segmentation provides stable mechanical and electrical bonding while keeping each component simple and manageable.

Inventive Principle:

Principle #1Segmentation

4Illumination intensity

If blue chip with yellow fluorescent substances is used, then white light can be generated, but color reproducibility is limited

Engineering Contradiction:

Improvewhite light generationVSAvoidcolor reproducibility

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent uses composite fluorescent materials including both yellow fluorescent substances (such as YAG:Ce) and red fluorescent substances (such as CaAlSiN3:Eu) in combination with the blue chip. This composite material approach broadens the spectral output and improves color reproducibility while maintaining efficient white light generation.

Inventive Principle:

Principle #40Composite materials

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 design improves light-using efficiency, reduces the thickness of the backlight assembly, enhances LED mounting stability, and increases color reproducibility by ensuring uniform light distribution and consistent orientation angles, while maintaining or improving the existing advantages of LED technology.

Implementation Method 1

Each of the LEDs includes a blue chip emitting blue light, a red fluorescent substance and a green fluorescent substance for converting the blue light into white light

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS8164710B2Backlight assembly and liquid crystal display apparatus having the same

Publication Date: 2012.04.24 FAIRLIGHT INNOVATIONS LLC

AI summary

A backlight assembly includes a light guide plate and a light-emitting module. The light guide plate guides light. The light-emitting module is disposed to face an incidence surface of the light guide plate. The light-emitting module includes a printed circuit board (PCB) vertically disposed to face the incidence surface and a plurality of LEDs mounted on the PCB to emit light toward the incidence surface. Each of the LEDs includes a blue chip emitting blue light, a red fluorescent substance and a green fluorescent substance for converting the blue light into white light. Therefore, a thickness of the backlight assembly is reduced and an LED-mounting stability of the LED is improved.