In-Cell Sensor Electrode Segmentation for Capacitive Coupling

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Solution Overview

Problem

Existing capacitive touch sensing technologies face challenges in efficiently managing transcapacitive coupling between transmitter and receiver electrodes, leading to impractical capacitive coupling values and potential display artifacts due to anisotropic dielectric properties of display materials.

Innovation Solution

The implementation of a capacitive touch sensing system with segmented transmitter electrodes, where common electrode segments are interleaved with non-driven segments to reduce transcapacitive coupling, and receiver electrodes are strategically positioned between color filters to minimize parallel-plate capacitance and maximize fringing-field capacitance, while maintaining effective touch sensing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If transmitter electrodes are used for both display updating and capacitive sensing, then device complexity is reduced, but transcapacitive coupling becomes impractical and display artifacts occur

Engineering Contradiction:

Improveelectrode configurationVSAvoidcapacitive coupling performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The transmitter electrode is divided into multiple segments (first plurality and second plurality of segments) that can be independently controlled. During capacitive sensing, only the first plurality of segments is driven while the second plurality is held at a different potential, effectively reducing transcapacitive coupling. This segmentation allows the same electrode structure to serve both display and sensing functions without performance degradation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrode configuration dynamically changes based on operating mode. The driver circuit selectively drives different portions of the transmitter electrode depending on whether display updating or capacitive sensing is being performed. This dynamic control optimizes performance for each specific function while using the same physical electrode structure.

Inventive Principle:

Principle #15Dynamics

2Reliability

If receiver electrodes are positioned between color filters, then parallel-plate capacitance is minimized and fringing-field capacitance is maximized, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecapacitive sensing accuracyVSAvoidelectrode alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The receiver electrodes are strategically positioned in specific locations between color filters where the local electromagnetic field characteristics are optimal. This positioning maximizes the fringing-field capacitance effect while minimizing parallel-plate capacitance, creating locally optimized sensing regions that leverage the anisotropic dielectric properties of the display material.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If common electrode segments are driven for both display and sensing, then ease of operation is improved, but transcapacitive coupling increases causing harmful effects

Engineering Contradiction:

Improveelectrode controlVSAvoidtranscapacitive coupling effects

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The system applies preliminary anti-action by holding the second plurality of electrode segments at a different potential before capacitive sensing begins. This pre-configured state creates an electrical condition that counteracts the transcapacitive coupling effect, allowing the first plurality of segments to be driven for sensing without experiencing harmful coupling to the receiver electrodes.

Inventive Principle:

Principle #9Preliminary anti-action

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 reduces impractical capacitive coupling values, maintains sensitivity to touch inputs, and minimizes display artifacts by optimizing the ratio of capacitive coupling to background capacitance, enhancing the overall performance of capacitive touch sensing in display devices.

Implementation Method 1

The first plurality of common electrode segments is capacitively coupled with the receiver electrode forming a transcapacitive coupling

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

the second plurality of common electrode segments are configured to reduce the transcapacitive coupling between the first plurality of common electrode segments and the receiver electrode

Methodology Applied

Scientific EffectElectrostatic shielding: Electrostatic Induction

Data Source

PatentUS9652072B2Full in-cell sensor

Publication Date: 2017.05.16 SYNAPTICS INC

AI summary

A display device having an integrated capacitive sensing device includes receiver electrodes disposed on a back side of a color filter glass. Transmitter electrodes of the capacitive sensing device are configured with a size and geometry that reduces the capacitive coupling between the transmitter and receiver electrodes. The transmitter electrodes may be made of one or more prongs or segments from a segmented common electrode.