Flexible Touch Substrate Notches Reduce Parasitic Capacitance

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Solution Overview

Problem

Existing touch devices typically have touch functionality limited to their light exit surface, which can obstruct displayed information and is inconvenient for users to interact with, especially when holding the device, as it restricts the screen-to-body ratio.

Innovation Solution

A flexible touch substrate with notches at its sides, allowing the substrate to be bent into a three-dimensional structure with multiple touch surfaces, including the front and lateral surfaces, enhancing the screen-to-body ratio by distributing touch electrodes and signal lines in a manner that maintains touch functionality across these surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If touch functionality is provided only on the light exit surface, then the structure is simple, but the touch region is limited and screen-to-body ratio is reduced

Engineering Contradiction:

Improvetouch regionVSAvoidsubstrate structure

Core Design Contradiction:

Area of moving objectVSDevice complexity

Solution Approach 1:

The patent extends touch functionality from a single flat surface to multiple surfaces by bending the flexible substrate into a three-dimensional configuration. The substrate is folded along notches to create front, lateral, and back surfaces with touch functionality, transforming a two-dimensional touch interface into a multi-dimensional one. This increases the total touch area while managing the complexity through systematic folding patterns.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The flexible substrate is divided into multiple independent touch regions corresponding to different surfaces (front surface, lateral surfaces, back surface). Each region contains its own touch electrodes and signal lines that are insulated from other regions. This segmentation allows each surface to function independently while simplifying the overall design by treating each surface as a separate touch module.

Inventive Principle:

Principle #1Segmentation

2Area of moving object

If multiple touch surfaces are created by bending the substrate, then the screen-to-body ratio is improved, but parasitic capacitance between signal lines increases

Engineering Contradiction:

Improveinteractive areaVSAvoidparasitic capacitance

Core Design Contradiction:

Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent removes portions of the flexible substrate to create notches at the corners and edges. These notches extract material that would otherwise form parasitic capacitance between adjacent signal lines on different surfaces. By taking out these specific regions, the design reduces unwanted electrical coupling while maintaining the structural integrity needed for multi-surface bending.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The notches, which create gaps and discontinuities in the substrate, are strategically positioned to break the path of parasitic capacitance between signal lines. What could be seen as structural weaknesses (gaps in the substrate) are converted into beneficial features that reduce electrical interference. The notches serve dual purposes: enabling flexible bending while simultaneously reducing parasitic capacitance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If touch electrodes are distributed across multiple surfaces, then the touch functionality is enhanced, but the insulation requirements between electrodes increase

Engineering Contradiction:

Improvetouch functionalityVSAvoidinsulation between signal lines

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The touch electrodes are segmented into distinct groups for different surfaces, with each group electrically isolated from others. The flexible substrate itself acts as an insulating layer between electrode groups on adjacent surfaces. Additional insulating layers are applied in regions where electrodes from different surfaces may be in close proximity, ensuring reliable electrical isolation while maintaining touch sensitivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible substrate serves as an intermediary insulating layer between touch electrodes on different surfaces. Its dielectric properties provide natural electrical isolation. In addition, dedicated insulating layers are introduced as intermediary elements in critical areas where the substrate thickness may be reduced during folding, ensuring that insulation requirements are met without compromising touch electrode functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10949045B2Flexible touch substrate and touch device that have reduced parasitic capacitance between different signal lines

Publication Date: 2021.03.16 HEFEI XINSHENG OPTOELECTRONICS TECH CO LTD

AI summary

A flexible touch substrate and a touch device including the flexible touch substrate are provided. The flexible touch substrate includes a plurality of sides. Each of at least one of the plurality of sides has notches at its both ends. Each of the notches has two edges whose extension directions cross each other, and the two edges of each of the notches have a same length.