Touch Screen Sensor Micropatterning for Electrical Gradient Control

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Solution Overview

Problem

Existing touch screen sensors face limitations in controlling electrical potential gradients and conductor design flexibility due to the use of continuous transparent conducting oxides like ITO, necessitating complex signal processing and additional electrodes.

Innovation Solution

The development of touch screen sensors with micropatterned conductive elements on a visible light transparent substrate, featuring regions with varying sheet resistance, anisotropic or isotropic properties, and metallic features less than 500 nanometers thick, allowing for controlled electrical potential gradients and flexible design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a continuous coating of transparent conducting oxide is used, then electrical conductivity is achieved, but control over electrical potential gradients is limited

Engineering Contradiction:

Improvecontrol over electrical potential gradientsVSAvoidsignal processing electronics and additional electrodes

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The continuous transparent conducting oxide coating is segmented into micropatterned regions with different sheet resistance values. This segmentation allows different areas of the touch sensor to have different electrical properties, enabling control over electrical potential gradients without additional electrodes or complex signal processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the micropatterned TCO are assigned different sheet resistance values tailored to local electrical requirements. This local quality variation enables precise control of electrical potential gradients in specific areas while maintaining overall sensor functionality.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If patterned transparent conducting oxides with single value isotropic sheet resistance are used, then fabrication is simplified, but conductor design flexibility is limited

Engineering Contradiction:

Improveconductor design flexibilityVSAvoidpatterning constraints

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The sheet resistance parameter of the TCO is varied across different regions of the micropattern, transitioning from a single uniform value to multiple distinct values. This parameter change enables diverse conductor designs with different electrical characteristics while using the same TCO material system.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure within the TCO layer by combining multiple regions with different sheet resistance values in a single micropatterned element. This composite approach provides design flexibility equivalent to using multiple different materials while maintaining compatibility with standard TCO fabrication processes.

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If higher sheet resistance regions are used, then optical transparency is improved, but electrical conductivity is reduced

Engineering Contradiction:

Improveoptical transparencyVSAvoidelectrical conductivity

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The TCO coating is segmented into regions with different sheet resistance values, allowing optically critical areas to use higher resistance (more transparent) TCO while electrically critical areas use lower resistance (more conductive) TCO. This spatial segmentation resolves the trade-off between transparency and conductivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the micropatterned TCO are assigned different sheet resistance values tailored to local requirements: higher resistance in regions prioritizing optical transparency and lower resistance in regions prioritizing electrical conductivity. This local optimization eliminates the need to compromise either property globally.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250306719A1Touch screen sensor

Publication Date: 2025.10.02 3M INNOVATIVE PROPERTIES CO

AI summary

A touch screen sensor includes a visible light transparent substrate and an electrically conductive micropattern disposed on or in the visible light transparent substrate. The micropattern includes a first region micropattern within a touch sensing area and a second region micropattern. The first region micropattern has a first sheet resistance value in a first direction, is visible light transparent, and has at least 90% open area. The second region micropattern has a second sheet resistance value in the first direction. The first sheet resistance value is different from the second sheet resistance value.