Backlight Unit Spacer Design for Display Light Guide Height Control

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Solution Overview

Problem

Existing backlight units for liquid crystal displays face challenges in maintaining uniform height and light diffusion efficiency due to the absence of a support structure for optical sheets on the light guide layer.

Innovation Solution

A backlight unit design featuring a light guide layer with a vacant space, supported by a spacer with alternately formed protrusions and recessed portions on its surfaces, which are adhered to a reflective and screening layer to maintain uniform height and enhance light transmission, reflection, and refraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light guide layer with vacant space is used to improve light diffusion efficiency, then light transmission is enhanced, but the height uniformity of the light guide layer deteriorates due to lack of support structure

Engineering Contradiction:
Improvelight diffusion efficiencyVSAvoidheight uniformity of light guide layer
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

A spacer is introduced as an intermediary component between the light guide layer and the reflective layer to maintain the vacant space height. The spacer prevents the light guide layer from collapsing while preserving the light diffusion benefits of the vacant space structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacer is designed with alternating protrusions and recessed portions that create localized support points. This local quality approach provides height uniformity at critical positions while maintaining the overall vacant space structure for light diffusion.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If optical sheets are placed directly on the light guide layer to improve light distribution, then illumination uniformity is enhanced, but the structural stability deteriorates causing sagging of the display panel

Engineering Contradiction:
Improveillumination uniformityVSAvoidstructural stability of display panel
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The spacer acts as a mediator that supports the optical sheets indirectly by maintaining the light guide layer structure. This prevents direct contact between optical sheets and light guide layer, reducing stress concentration and preventing sagging while maintaining illumination uniformity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacer is pre-installed to establish the correct height and spacing before optical sheets are placed. This preliminary action prevents structural collapse and ensures proper positioning of optical components during assembly.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the light guide layer height is increased to improve light diffusion, then light transmission efficiency is enhanced, but the risk of light guide layer deformation increases

Engineering Contradiction:
Improvelight transmission efficiencyVSAvoidresistance to deformation of light guide layer
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The spacer serves as a mediator that defines and maintains the light guide layer height. By providing rigid support at the spacer locations, the light guide layer can maintain increased height for better light diffusion without deforming under its own weight or external pressure.

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 configuration ensures uniform luminescence and maintains the height of the light guide layer, improving light diffusion efficiency and preventing sagging of the display panel.

Implementation Method 1

the plurality of protrusions are adhered to the reflective layer and the screening layer by an adhesive

Methodology Applied
Scientific EffectAdhesive: Adhesive

Implementation Method 2

a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer

Methodology Applied
Scientific EffectMechanical support:

Implementation Method 3

a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 4

a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted

Methodology Applied
Scientific EffectLight transmission and filtering: Filter (optical)

Data Source

PatentEP2876490B1Display device
Publication Date: 2019.01.02 LG ELECTRONICS INC
  • EP2876490B1 patent drawingFigure 1
  • EP2876490B1 patent drawingFigure 2
  • EP2876490B1 patent drawingFigure 3~4

AI summary

A display device, according to one embodiment of the present invention, comprises a display panel; and a backlight unit providing light from a lower side of the display panel, wherein the backlight unit comprises: a bottom cover; a light source module mounted on the bottom cover and including: a plurality of light sources arranged at uniform intervals; and a circuit board on which the plurality of light sources are mounted; a reflective layer placed above the light source module to reflect the light emitted from the light sources towards the display panel; a screening layer disposed over the reflective layer at a distance therefrom and having a plurality of patterned holes to allow only a portion of the light reflected from the reflective layer to be transmitted; and a spacer disposed between the reflective layer and the screening layer to form a light guide layer defined by a vacant space between the reflective layer and the screening layer and to maintain the uniform height of the light guide layer.