Irregular Capacitive Electrode Layout for 3D Touch Sensing

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Solution Overview

Problem

Current capacitive touch screen technologies face challenges in effectively sensing the position and proximity of a user's finger, particularly in providing accurate three-dimensional sensing and obscuring the visibility of conductive micro-patterns, with existing designs often relying on regular configurations and straight traces that may not adequately address irregular finger movements or positions.

Innovation Solution

The use of distinct capacitive sensor electrodes with irregular configurations and jagged perimeters, distributed as islands across a sensing area, along with conductive traces that extend over the area, allowing for unique positional sensing and three-dimensional detection by aligning and misaligning these electrodes to create a tessellated array that matches opposing perimeters and maintains a fixed gap, enabling precise touch detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If regular configurations and straight traces are used for capacitive sensor electrodes, then manufacturing is easier and device complexity is reduced, but measurement precision and three-dimensional sensing accuracy deteriorate

Engineering Contradiction:
Improvetouch sensing accuracyVSAvoidelectrode configuration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by configuring capacitive sensor electrodes in irregular patterns rather than regular grids, with non-uniform spacing and orientations. This asymmetric arrangement enables the sensing system to detect three-dimensional finger positions and movements more accurately, resolving the contradiction between measurement precision and device complexity by accepting increased configurational complexity to achieve superior sensing capability.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent transitions from two-dimensional regular electrode arrangements to three-dimensional irregular configurations, where electrodes are positioned at varying depths and angles. This dimensional change allows the system to sense finger proximity and orientation in 3D space, improving measurement precision while the irregular nature of the configuration prevents simple manufacturing patterns.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If conductive traces extend over the sensing area to connect irregularly configured electrodes, then sensing coverage and measurement precision improve, but visibility of micro-patterns increases and aesthetic quality deteriorates

Engineering Contradiction:
Improveposition detection accuracyVSAvoidvisibility of conductive patterns
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent applies local quality by making conductive traces transparent or translucent only in regions where they extend over the sensing area, while maintaining opaque properties in non-sensing regions. This allows the traces to electrically connect irregularly configured electrodes for precise position detection while remaining visually imperceptible when viewed through the transparent display, thus resolving the contradiction between sensing coverage and aesthetic quality.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs optical property changes by using transparent or translucent conductive materials for traces covering the sensing area, allowing light to pass through without significant absorption or reflection. This enables the traces to perform their electrical function while being visually hidden, improving both position detection accuracy and the visual appearance of the display.

Inventive Principle:
Principle #32Color changes

3Adaptability or versatility

If irregular configurations with jagged perimeters are used for capacitive sensor electrodes, then three-dimensional sensing capability and adaptability improve, but manufacturing precision requirements increase

Engineering Contradiction:
Improvefinger movement detection capabilityVSAvoidelectrode configuration precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by designing irregular electrode configurations with jagged perimeters that can adapt to various finger positions, sizes, and movement patterns. These dynamic, non-uniform shapes enable the sensing system to detect a wider range of finger interactions in three dimensions, improving adaptability while the irregular geometry prevents simple manufacturing processes from being used, thereby increasing precision requirements.

Inventive Principle:
Principle #15Dynamics

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 configuration enhances the accuracy of touch sensing by allowing for precise detection of finger position and proximity in two and three dimensions, while also obscuring the visibility of the conductive micro-patterns, improving user interaction with touch-sensitive displays.

Implementation Method 1

The capacitive sensor electrodes sense a proximal conductive object such as a user's finger touching the sensing area or hovering on top of it.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2997450B1An apparatus comprising a plurality of capacitive sensor electrodes
Publication Date: 2021.09.29 NOKIA TECHNOLOGIES OY
  • EP2997450B1 patent drawingFigure 1~3
  • EP2997450B1 patent drawingFigure 4
  • EP2997450B1 patent drawingFigure 5~6B

AI summary

An apparatus comprising: distinct capacitive sensor electrodes (6) irregularly configured across a sensing area (8), wherein each capacitive sensor electrode is an island associated with a unique combination of two positional components within the sensing area; and a plurality of conductive traces (10) each of which is operatively connected to one of the distinct capacitive sensor electrodes and wherein at least some of the conductive traces extend over the sensing area.