Shadow Elimination in Capacitive Touch Screens

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Solution Overview

Problem

Current capacitance type touch screens face issues with apparent etching textures due to large differences in reflectivity between patterned and non-patterned regions of the ITO layer, leading to degraded visual effects and increased production time for shadow elimination.

Innovation Solution

A shadow elimination arrangement comprising a silicon oxynitride layer with refractivity in the range of 1.47-2.0, deposited below the ITO layer, and a silicon dioxide layer above it, to equalize reflectivity between patterned and non-patterned regions, along with additional protection for the ITO layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single layer or multiple layers of structure consisted of Nb2O5 film and SiO2 film is deposited between substrate and electrode to eliminate shadow, then shadow elimination effect can be observed, but production time is significantly extended and defects cannot be detected timely

Engineering Contradiction:

Improveshadow elimination effectVSAvoidproduction time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The shadow elimination layer is deposited before the ITO electrode layer, allowing the shadow elimination effect to be established in advance. This preliminary action enables defect detection after ITO etching without requiring additional production time, as the shadow elimination structure is already in place to modify light reflection characteristics.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The shadow elimination layer acts as an intermediary between the substrate and the ITO electrode layer. It mediates the optical interaction by controlling light reflection and refraction, thereby eliminating shadows caused by ITO pattern etching while maintaining production efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If ITO layer is etched to form patterned region and non-patterned region, then touch sensor functionality is achieved, but large difference in reflectivity between regions causes apparent etching texture and degraded visual effect

Engineering Contradiction:

Improvetouch sensor functionalityVSAvoidetching texture visibility

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The shadow elimination layer has different optical properties in different regions corresponding to the patterned and non-patterned ITO areas. By controlling the thickness and material composition locally, it compensates for the reflectivity difference between etched and non-etched regions, making the etching texture invisible while preserving touch sensor functionality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The shadow elimination layer modifies optical parameters (reflectivity, refractivity) to compensate for the reflectivity difference caused by ITO etching. By adjusting the thickness and material composition of this layer, the overall optical appearance is uniformized, eliminating the visual impact of etching textures.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If Nb2O5 film and SiO2 film structure is deposited to eliminate shadow, then shadow reduction is achieved, but transmittivity of touch screen is not improved

Engineering Contradiction:

Improveshadow eliminationVSAvoidlight transmittivity

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The shadow elimination layer uses a composite structure combining SiO2 and Nb2O5 materials with specific thickness ratios. This composite material approach optimizes both shadow elimination and light transmittivity by leveraging the complementary optical properties of different materials - SiO2 for low refractive index and Nb2O5 for high refractive index, creating an anti-reflective effect that improves transmittivity while eliminating shadows.

Inventive Principle:

Principle #40Composite materials

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

Effectively eliminates the appearance of etching textures and allows for timely detection of defects, improving the visual quality and transmittivity of the touch screen.

Implementation Method 1

a silicon oxynitride layer, on which the pattern of ITO layer is provided, being provided on a transparent substrate

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a silicon dioxide layer, provided over the pattern of the ITO layer

Methodology Applied

Scientific EffectPhysical barrier protection:

Data Source

PatentUS10198134B2Shadow elimination arrangement, touch screen and method for producing the same

Publication Date: 2019.02.05 BOE TECHNOLOGY GROUP CO LTD

AI summary

Embodiments of the present application provide a shadow elimination arrangement, a touch screen and a method for producing the same. The shadow elimination arrangement for a pattern of an ITO layer includes a silicon oxynitride layer, on which the pattern of the ITO layer is provided, being provided on a transparent substrate; and a silicon dioxide layer, provided over the pattern of the ITO layer.