Multi-Layer Capacitive Sensor Electrodes for 3D Touch Detection

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Solution Overview

Problem

Current capacitive touch sensitive displays face challenges in accurately detecting touch inputs, particularly in reducing areas of decreased detection sensitivity and providing three-dimensional sensing capabilities.

Innovation Solution

The apparatus employs a plurality of capacitive sensor electrodes distributed over a sensing area in multiple layers, with conductive traces connected to these electrodes, allowing for two- and three-dimensional sensing by detecting variations in capacitance from user inputs, including positional data of fingers both touching and hovering above the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive sensor electrodes are distributed in a single layer, then the device structure is simple, but the detection sensitivity and three-dimensional sensing capability are insufficient

Engineering Contradiction:
Improvedetection sensitivityVSAvoiddevice structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from a single-layer electrode arrangement to a multi-layer electrode configuration, adding the vertical dimension (z-axis) to the traditional planar (x-y plane) electrode distribution. This dimensional expansion enables three-dimensional sensing capabilities and improves detection sensitivity by allowing the system to detect touches from different depths and angles, while the layered structure itself provides a systematic approach that manages the increased complexity through organized spatial arrangement.

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

2Adaptability or versatility

If multiple layers of capacitive sensor electrodes are used, then three-dimensional sensing capability is improved, but the device complexity increases

Engineering Contradiction:
Improvethree-dimensional sensing capabilityVSAvoiddevice structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the sensing function into multiple discrete layers, with each layer containing electrode arrays that can be independently configured and addressed. This segmentation allows the system to achieve three-dimensional sensing capability by stacking multiple functional units, while managing complexity through modular design where each layer can be manufactured and tested separately before assembly into the complete multi-layer structure.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If electrode traces are routed under capacitive sensor electrodes, then manufacturing is simplified, but detection sensitivity decreases in certain areas

Engineering Contradiction:
Improvetrace routingVSAvoiddetection sensitivity
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies different trace routing strategies to different regions of the electrode array. In areas where manufacturing simplicity is prioritized, traces are routed underneath electrodes. In areas where detection sensitivity is critical, traces are routed around or alongside electrodes to minimize interference. This localized differentiation of routing approaches allows the system to optimize for either manufacturing ease or detection sensitivity depending on the specific functional requirements of each region.

Inventive Principle:
Principle #3Local quality

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 touch detection accuracy and sensitivity, enabling reliable two-dimensional and three-dimensional sensing capabilities, improving user input detection and interaction with touch-sensitive displays.

Implementation Method 1

The capacitive sensor electrodes sense a proximal grounded object such as a user's finger touching the sensing area

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2994816B1Touch sensor array and method therefor
Publication Date: 2022.07.20 NOKIA TECHNOLOGIES OY
  • EP2994816B1 patent drawingFigure 1~3
  • EP2994816B1 patent drawingFigure 4A~4C
  • EP2994816B1 patent drawingFigure 5A~5C

AI summary

An apparatus comprising: a sensing arrangement comprising: a first array of capacitive sensor electrodes comprising a first plurality of distinct capacitive sensor electrodes distributed in a first layer over a first sensing area; first conductive traces operatively connected to the first plurality of distinct capacitive sensor electrodes; a second array of capacitive sensor electrodes comprising a second plurality of distinct capacitive sensor electrodes distributed in a second layer over a second sensing area, wherein the first layer and the second layer are different layers; and second conductive traces operatively connected to the second plurality of distinct capacitive sensor electrodes.