Adhesive Bonding for Narrow Bezel LCD Light Leakage

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Solution Overview

Problem

Conventional liquid crystal display (LCD) devices face challenges in achieving a narrow bezel and preventing light leakage due to the limitations of existing fixing methods, such as the use of tapes which restrict bezel width and increase fabrication costs, and light leakage through white-colored frames.

Innovation Solution

A display device is fabricated using an adhesive to attach and fix the liquid crystal panel to frames, allowing for a narrow bezel and preventing light leakage, with the adhesive being applied via a coating method and hardened through curing, potentially using black-colored adhesives to absorb light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a tape is used to fix the liquid crystal panel to the frame, then the panel is attached and fixed, but the bezel width cannot be reduced below about 1.0 mm due to the working limit of the tape

Engineering Contradiction:

Improvebezel widthVSAvoidfixing precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from tape to adhesive, which has different physical properties. The adhesive can be applied in a thin layer (0.1-1.0 mm) compared to tape minimum width (1.0 mm), enabling narrower bezels while maintaining fixing precision through proper adhesive formulation and application control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical fixing system (tape with physical adhesion) with a chemical bonding system (adhesive with molecular bonding). This substitution allows for thinner application layers and more precise control over the fixing interface, enabling bezel widths below the tape working limit

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If the tape width is increased to about 1.5 mm for sufficient fixing force, then the fixing strength is improved, but the black matrix area and bezel area increase to about 1.5-2.3 mm

Engineering Contradiction:

Improvefixing strengthVSAvoidbezel area

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The patent changes the adhesive material parameters (viscosity, curing characteristics, bond strength) to achieve sufficient fixing strength in a thin layer (0.1-1.0 mm). This eliminates the need to increase the application width for strength, allowing narrow bezels while maintaining adequate fixing force

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

By replacing mechanical tape fixing with chemical adhesive bonding, the patent achieves sufficient fixing strength through molecular adhesion rather than mechanical interlocking. This allows the adhesive to be applied in a thin layer without compromising strength, thus reducing the bezel area

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Illumination intensity

If a white colored main frame is used to reflect light and improve brightness, then the brightness is improved, but light leakage occurs through the side surface of the frame

Engineering Contradiction:

ImprovebrightnessVSAvoidlight leakage

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different properties to different parts of the frame system. The main frame remains white for brightness, while the adhesive layer is formulated with light-absorbing properties to prevent light leakage. This local differentiation allows both brightness improvement and light leakage prevention

Inventive Principle:

Principle #3Local quality

4Reliability

If additional fixing members are used to secure the panel, then the fixing reliability is improved, but the fabrication cost increases

Engineering Contradiction:

Improvefixing reliabilityVSAvoidfabrication cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple functions into the adhesive material: attachment, fixation, sealing, and light leakage prevention. This consolidation eliminates the need for separate fixing members, reducing fabrication cost while maintaining or improving fixing reliability through the multi-functional adhesive system

Inventive Principle:

Principle #5Merging (Combining)

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 enables the production of LCD devices with a narrow bezel and reduced fabrication costs by stabilizing the panel attachment and minimizing light leakage without the need for additional fixing members, while maintaining brightness.

Implementation Method 1

the adhesive may have a black color to absorb light and to prevent a light leakage through a side surface of the LCD device

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

the adhesive being applied via a coating method and hardened through curing

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS9869893B2Display device and method of fabricating the same

Publication Date: 2018.01.16 LG DISPLAY CO LTD

AI summary

A display device can include a display panel displaying an image, a first frame surrounding the display panel, a backlight unit under the display panel, and an adhesive between a side surface of the display panel and a side surface of the first frame. Also, the display panel is attached and fixed to the first frame by the adhesive.