OLED Touch Electrode Placement Between Substrate and Passivation

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Solution Overview

Problem

Organic light emitting diode (OLED) displays with touch sensing functionality face challenges in thickness and weight due to the use of glass substrates for touch sensing, which compromise their slim and lightweight design.

Innovation Solution

A display device architecture that incorporates a touch electrode between the rear substrate and the passivation layer, connected to the pixel electrode, and configured to form a capacitance component upon touch, allowing for touch sensing without increasing the device's thickness or weight, using transparent or reflective conductive materials and semiconductor materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a glass substrate is used for touch sensing in OLED displays, then touch sensing functionality is achieved, but the device thickness and weight increase

Engineering Contradiction:

Improvetouch sensing functionalityVSAvoiddevice weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The touch electrode is merged with the existing OLED structure by positioning it between the rear substrate and passivation layer, integrating touch sensing functionality into the display device without adding separate components. This combines the display and touch sensing functions into a unified structure, achieving touch capability while avoiding the weight penalty of separate glass touch substrates

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The OLED display structure is designed to serve multiple functions: the touch electrode formed within the display stack enables touch sensing, while the same structure maintains display functionality. The common electrode and emission layer serve both display and touch sensing purposes, achieving multi-functionality without additional weight

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a glass substrate is used for touch sensing in OLED displays, then touch sensing functionality is achieved, but the device thickness increases

Engineering Contradiction:

Improvetouch sensing functionalityVSAvoiddevice thickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The touch sensing function is merged into the existing OLED layer structure by forming the touch electrode within the display stack between the rear substrate and passivation layer. This integration eliminates the need for separate thick glass touch substrates, maintaining the slim profile of OLED displays while enabling touch capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The touch electrode is positioned in a different spatial dimension within the OLED stack rather than adding a separate layer. By utilizing the space between the rear substrate and passivation layer, the invention achieves touch sensing without increasing the overall device thickness, effectively using dimensional optimization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If transparent or reflective conductive materials are used for the touch electrode, then touch sensing is enabled, but manufacturing complexity increases

Engineering Contradiction:

Improvetouch sensing capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The invention allows flexibility in material selection by specifying different conductivity types (transparent or reflective) based on display requirements. This parameter change approach enables optimization of both touch sensing performance and manufacturing processes, as the material choice can be adjusted without fundamentally changing the device architecture

Inventive Principle:

Principle #35Parameter changes

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

Enables the integration of touch sensing functionality into OLED displays without increasing thickness or weight, maintaining the advantages of OLED technology such as low power consumption and high contrast ratio.

Implementation Method 1

configured to form a capacitance component when a touch is generated

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

electrons injected from the cathode and holes injected from the anode are coupled with each other in the light emitting layer to form excitons, and the excitons emit light while discharging energy

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11307715B2Display device and touch sensing method thereof

Publication Date: 2022.04.19 SAMSUNG DISPLAY CO LTD

AI summary

In a display device, a driving element is disposed on a rear substrate, and a passivation layer covers the driving element. A pixel electrode is disposed on the passivation layer and is connected to the driving element. An organic emission layer is disposed on the pixel electrode and is configured to emit light toward the rear substrate. A common electrode is disposed on the organic emission layer. A touch electrode is disposed between the rear substrate and the passivation layer, and it forms a capacitive component when an external touch occurs.