Capacitive Touch Panel Electrode Geometry for Low Coupling Capacitance

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Solution Overview

Problem

Conventional capacitive touch panels experience high lateral capacitance and overall coupling capacitance, leading to increased system loading and limitations in multi-input processing and fingerprint recognition, requiring a minimum applied pressure for operation.

Innovation Solution

The capacitive touch panel design features a dielectric layer between electrode strings with reduced electrode widths and unique perimeter shapes to minimize the effective overlapping area, reducing lateral capacitance between electrodes, and incorporating a grid structure with interlacing first and second direction electrode strings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional capacitive touch panels use quadrilateral electrodes with longer effective corresponding length between electrodes, then the touch detection capability is improved, but the lateral capacitance between electrodes increases and overall coupling capacitance increases which increases system loading

Engineering Contradiction:

Improvetouch detection capabilityVSAvoidsystem loading

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the conventional quadrilateral electrodes into two separate electrode strings (first direction electrode string and second direction electrode string) with electrodes distributed along different directions. This segmentation reduces the effective overlapping area between adjacent electrodes, thereby reducing lateral capacitance while maintaining touch detection capability through the grid structure formed by interlacing electrode strings

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-plane quadrilateral electrode layout to a multi-dimensional grid structure where first electrodes are distributed along a first direction and second electrodes are distributed along a second direction. This dimensional change allows for reduced electrode width in each direction while maintaining overall coverage and detection capability, thus reducing coupling capacitance

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the distance between electrodes is increased to reduce lateral capacitance, then the coupling capacitance decreases, but the effective overlapping area for creating capacitance is reduced which affects touch detection sensitivity

Engineering Contradiction:

Improvecoupling capacitanceVSAvoidtouch detection sensitivity

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies different electrode width characteristics to different parts of the electrode structure. The electrode width is reduced from the middle of the electrode to two sides along the distribution direction, creating a local quality variation that reduces effective overlapping area and lateral capacitance while maintaining sufficient capacitance for touch detection at critical contact points

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameters of electrodes by reducing electrode width and introducing slope change rates in the electrode perimeter. These parameter changes optimize the balance between reducing lateral capacitance and maintaining touch detection sensitivity by controlling the effective overlapping area through precise dimensional adjustments

Inventive Principle:

Principle #35Parameter changes

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 design effectively reduces lateral capacitance and system loading, enabling improved multi-input processing and fingerprint recognition without the need for minimum applied pressure, enhancing user interaction and system efficiency.

Implementation Method 1

a dielectric layer disposed between the first direction electrode strings and the second direction electrode strings, and used to electrically isolate first direction electrode strings and the second direction electrode strings

Methodology Applied

Scientific EffectDielectric isolation: Dielectric

Implementation Method 2

The lateral sides of electrodes 31 on the same or on different electrode layers have longer effective corresponding length between electrodes 31. The distance between electrodes 31 is not changed and this creates a larger effective overlapping area for creating capacitance between electrodes 31

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8310463B2Capacitive touch panel with low coupling capacitance and display device using the capacitive touch panel

Publication Date: 2012.11.13 AU OPTRONICS CORP

AI summary

A capacitive touch panel and a display device using the capacitive touch panel are provided. The capacitive touch panel includes a plurality of first direction electrode strings and second direction electrode strings. Each first direction electrode string has a plurality of first electrodes while each second direction electrode has a plurality of second electrodes. In order to reduce the lateral capacitance between adjacent electrodes, width of the first electrode is reduced from the middle to two sides of the electrode along a second direction. In addition, the first electrode has a perimeter surrounding itself. Each quarter of the perimeter of the first electrode facing the adjacent second electrode has a first slope change rate and a different second slope change rate.