Resistive Touch Screen With Carbon Resistance Layer For Flexible OLED

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Solution Overview

Problem

Capacitive touch screens have a limited use range and cannot achieve large angle bending due to the need for conductors, which restricts their functionality, especially in high temperature or cold environments, and limits the flexibility of organic light emitting diode (OLED) displays.

Innovation Solution

A resistive touch screen is developed with conductive traces and a carbon resistance layer made of fullerene on a flexible cover plate, forming an inductive resistive layer that changes resistance with external pressure, allowing for touch control without conductors and enabling arbitrary bending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If capacitive touch technology is used with conductors, then touch control can be achieved, but the device cannot bend at large angles and has limited flexibility

Engineering Contradiction:

Improvetouch control capabilityVSAvoidbending flexibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent replaces the traditional capacitive touch mechanism (which requires conductive materials and rigid structures) with a resistive touch mechanism using carbon-based materials. The conductive traces are replaced with carbon patterns that can be printed directly on flexible substrates, eliminating the mechanical constraints of traditional conductor-based touch screens and enabling large-angle bending.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs flexible cover plates and thin film structures with printed carbon resistance layers instead of rigid glass and conductor layers. This allows the touch screen to be bent at large angles while maintaining touch functionality, as the flexible substrate and printed carbon patterns can accommodate deformation without breaking the conductive pathways.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If capacitive touch screens use conductors on cover plate glass or film, then touch sensing is achieved, but the structure becomes complex and cost increases

Engineering Contradiction:

Improvetouch sensing capabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the cover plate, conductive traces, and resistance layer into a single integrated structure. The carbon patterns are printed directly on the flexible cover plate, combining what were previously separate components (conductive layer, resistance layer, and substrate) into one simplified structure, reducing both complexity and manufacturing steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses printed carbon patterns instead of expensive etched conductor traces on glass. The printing process is more cost-effective than traditional photolithography and etching, and the flexible carbon-based structure can be manufactured more simply, reducing overall device cost while maintaining touch sensing reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If traditional capacitive touch technology is used, then touch control works in standard conditions, but it fails in high temperature or cold environments

Engineering Contradiction:

Improvetouch control functionalityVSAvoidenvironmental temperature range

Core Design Contradiction:

Ease of operationVSTemperature

Solution Approach 1:

The patent changes the material parameters from traditional capacitive materials (which are sensitive to temperature) to carbon-based resistive materials that maintain stable electrical properties across a wide temperature range. The carbon resistance layer's electrical characteristics remain consistent in both high and low temperature environments, enabling reliable touch control where capacitive technology fails.

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

This solution expands the usable range of touch screens to include non-conductor inputs and high/low temperature environments, simplifies the structure, reduces costs, and allows for flexible OLED display designs without the need for polarizing plates or touch pads.

Implementation Method 1

a carbon resistance layer printed on the cover plate between the conductive traces, wherein the conductive traces are electrically connected to the carbon resistance layer to form an inductive resistive layer

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

depositing an indium tin oxide (ITO) layer on the cover plate using a magnetron sputtering process

Methodology Applied

Scientific EffectMagnetron sputtering: Sputtering

Implementation Method 3

etching the conductive traces out of the ITO layer using a laser etching process

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS11309366B2Resistive touch screen, organic light emitting diode display, and manufacturing method thereof

Publication Date: 2022.04.19 WUHAN CHINA STAR OPTOELECTRONICS SEMICONDUCTOR DISPLAY TECHNOLOGY CO LTD

AI summary

A resistive touch screen includes: a cover plate; conductive traces formed on the cover plate; a carbon resistance layer printed on the cover plate between the conductive traces, wherein the conductive traces are electrically connected to the carbon resistance layer to form an inductive resistive layer, and a resistance value can be changed by external pressure to achieve touch control.