Micro-Cavity Display Device with Interlayer Insulating Trenches

Solution Overview

Problem

The complexity and time required for forming micro-cavity structures in display devices, particularly due to thickness differences in transparent electrodes, lead to increased process complexity and potential damage from pressure variations during substrate attachment, affecting the reliability and luminous efficacy of the display.

Innovation Solution

A display device with an interlayer insulating layer featuring trenches of varying depths for each pixel area, where the light-emitting structures include a reflective electrode, resonant layer, and transparent electrode stacked sequentially, with the resonant layer being thinner and having higher transmissivity than the transparent electrode, allowing for coplanar upper surfaces and reduced height differences, thus simplifying the formation process and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the transparent electrode thickness is adjusted to form micro-cavity structures for different colors, then luminous efficacy is improved, but process complexity increases and production time increases

Engineering Contradiction:

Improveluminous efficacyVSAvoidprocess complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges the micro-cavity structure formation into a single etching process by defining trenches of different depths in the interlayer insulating layer before depositing the transparent electrode. This combines what would otherwise require multiple separate etching and deposition steps into one integrated process, reducing process complexity while maintaining the color-specific optical path differences needed for high luminous efficacy

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary action by pre-defining trenches of varying depths in the interlayer insulating layer before transparent electrode deposition. This preliminary structuring allows the transparent electrode to be deposited uniformly across all pixel areas while naturally forming different optical cavity thicknesses, eliminating the need for subsequent thickness-adjustment processes

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the transparent electrode thickness is adjusted to form micro-cavity structures for different colors, then luminous efficacy is improved, but production time increases

Engineering Contradiction:

Improveluminous efficacyVSAvoidproduction time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent merges multiple process steps into a single etching operation that creates all required trench depth variations simultaneously. This consolidation reduces the total number of process cycles needed, directly decreasing production time while preserving the optical path differences necessary for achieving high luminous efficacy in each color pixel

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary action by pre-defining trenches of varying depths in the interlayer insulating layer before transparent electrode deposition. This preliminary structuring allows the transparent electrode to be deposited uniformly across all pixel areas while naturally forming different optical cavity thicknesses, eliminating the need for subsequent thickness-adjustment processes

Inventive Principle:

Principle #10Preliminary action

3Reliability

If transparent electrodes of different thicknesses are formed on pixel areas, then micro-cavity structure is achieved, but height difference occurs causing pressure variation and potential damage

Engineering Contradiction:

Improvemicro-cavity structure reliabilityVSAvoidpressure variation damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent resolves the height difference problem by shifting the thickness variation from the transparent electrode layer to the underlying interlayer insulating layer. By defining trenches of different depths in the insulating layer, the micro-cavity optical path differences are achieved while the transparent electrode surface remains coplanar, eliminating pressure variation damage during attachment

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces the interlayer insulating layer with depth-varying trenches as an intermediary structure between the substrate and the transparent electrode. This intermediary layer absorbs the thickness variation needed for micro-cavity formation, allowing the transparent electrode to maintain uniform thickness and coplanar upper surfaces, thus preventing pressure-related damage

Inventive Principle:

Principle #24Intermediary (Mediator)

4Manufacturing precision

If multiple etching or deposition processes are used to form transparent electrodes of different thicknesses, then color-specific optical paths are achieved, but process complexity and time increase

Engineering Contradiction:

Improveoptical path precisionVSAvoidproduction efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs preliminary action by pre-defining trenches of varying depths in the interlayer insulating layer before transparent electrode deposition. This preliminary structuring allows the transparent electrode to be deposited uniformly across all pixel areas while naturally forming different optical cavity thicknesses, eliminating the need for subsequent thickness-adjustment processes

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent resolves the height difference problem by shifting the thickness variation from the transparent electrode layer to the underlying interlayer insulating layer. By defining trenches of different depths in the insulating layer, the micro-cavity optical path differences are achieved while the transparent electrode surface remains coplanar, eliminating pressure variation damage during attachment

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 approach simplifies the formation process of micro-cavity structures, enhances luminous efficacy, and improves the reliability of the display device by ensuring consistent thickness and reduced pressure variations across pixel areas.

Implementation Method 1

a first resonant layer and a first transparent electrode, which are sequentially stacked... A second resonant layer and a second transparent electrode, which are sequentially stacked

Methodology Applied

Scientific EffectOptical resonance: Resonance

Data Source

PatentEP3291326B1Display device having a micro-cavity structure and method for forming the same

Publication Date: 2020.07.15 LG DISPLAY CO LTD

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Figure 3A

AI summary

A display device including a micro-cavity structure and a method for forming the same is provided. The display device includes light-emitting structures on pixel areas. In the display device, each of the pixel areas may realize a color different from an adjacent pixel area. In the display device, each of the light-emitting structures may include a reflective electrode, a resonant layer and a transparent electrode. which are sequentially stacked. In the display device, a side surface of the resonant layer and a side surface of the transparent electrode of the light-emitting structure may be surrounded by an interlayer insulating layer. Thus, in the display device, the reliability and the production efficiency may be improved.