Alignment Layer Thickness Variation for Reliable Electrical Connections

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Solution Overview

Problem

Conventional liquid crystal display panels face issues with light leakage due to misalignment of the alignment layer, which obstructs electrical connections and affects the alignment of liquid crystal molecules, especially in designs requiring a slim bezel or large usable area.

Innovation Solution

The display panel is designed with a first and second region, where the alignment layers have varying thicknesses, allowing the conductive member to penetrate and connect the electrode layer and pad without obstruction, and the alignment layer is preserved to prevent light leakage by modulating the thickness ratio between these regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the alignment layer is formed with uniform thickness across the entire substrate, then the manufacturing process is simple, but the conductive member cannot penetrate the alignment layer to connect the electrode layer and pad, causing light leakage

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidalignment layer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The alignment layer is designed with different thicknesses in different regions: a first thickness in the display region and a second thickness (smaller than the first) in the peripheral circuit region. This local differentiation allows the conductive member to penetrate the thinner alignment layer in the peripheral region to establish electrical connections, while maintaining the thicker alignment layer in the display region to prevent light leakage and ensure proper liquid crystal alignment.

Inventive Principle:

Principle #3Local quality

2Reliability

If the alignment layer thickness is reduced in the second region to allow conductive member penetration, then electrical connection is enabled, but light leakage prevention capability is reduced

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidlight leakage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The alignment layer thickness is locally optimized: in the peripheral circuit region (second region), the thickness is reduced to enable conductive member penetration for reliable electrical connections; in the display region (first region), the thickness is maintained at a larger value to ensure effective light leakage prevention and proper liquid crystal alignment. This spatial differentiation resolves the contradiction between electrical connection requirements and light leakage prevention.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the alignment layer is kept thick throughout to prevent light leakage, then display quality is maintained, but the conductive member is obstructed from establishing electrical connections

Engineering Contradiction:

Improvelight leakage preventionVSAvoidelectrical connection reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The alignment layer is designed with region-specific thickness: a larger thickness in the display region to prevent light leakage and maintain display quality, and a smaller thickness in the peripheral circuit region to allow conductive member penetration for establishing electrical connections between the electrode layer and pad. This local differentiation simultaneously satisfies both requirements.

Inventive Principle:

Principle #3Local quality

4Area of stationary object

If the bezel is made slim to increase usable area, then the display panel design is improved, but misalignment between substrates causes the alignment layer to obstruct conductive members

Engineering Contradiction:

Improveusable areaVSAvoidelectrical connection reliability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

In the peripheral circuit region where misalignment is most critical for slim bezel designs, the alignment layer thickness is reduced to enable conductive member penetration even when misalignment occurs. This local thinning ensures that electrical connections remain reliable while maintaining the slim bezel design and maximizing usable display area.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8223309B2Display panel having different thickness of alignment layers in different regions

Publication Date: 2012.07.17 AU OPTRONICS CORP

AI summary

A display panel provided with a first region and a second region includes an active device array substrate, an opposite substrate, a display medium between the active device array substrate and the opposite substrate and a conductive member. The active device array substrate includes an active device array, a pad located in the second region and a first alignment layer covering the first region and the second region. The opposite substrate includes an electrode layer and a second alignment layer covering the electrode layer. The ratio of a thickness of the first or second alignment layer in the second region to that in the first region is substantially greater than zero and less than or equal to about 0.43. The conductive member is located in the second region and corresponding to the pad and penetrates the first alignment layer and the second alignment layer to connect the electrode layer and the pad.