Double-Sided Touch Panel Shielding Vcom Noise

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional capacitive touch sensor panels require larger sizes due to non-overlapping flex circuit connection areas on opposite sides of the dielectric, and they suffer from noise interference from a modulated Vcom layer when bonded to an LCD.

Innovation Solution

A novel fabrication process forms column and row traces on both sides of a substrate, using copper or other conductive metals along the edge to connect flex circuits to the same edge, minimizing the panel size and incorporating wider row traces to shield against Vcom layer noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If flex circuit connection areas are placed on opposite sides of the dielectric, then electrical connections can be established, but the panel size increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpanel size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the flex circuit connection areas onto a single side of the dielectric layer by routing both row and column trace connections to the same edge. This merging of connection areas eliminates the need for separate connection zones on opposite sides, thereby reducing the overall panel size while maintaining reliable electrical connections to both trace types.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes the edge dimension of the dielectric layer to route both row and column flex circuit connections to the same side. By transitioning from a two-sided connection arrangement to a single-sided edge-routed connection, the panel footprint is reduced without compromising connection reliability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If conventional trace routing is used, then manufacturing is simpler, but noise interference from Vcom layer occurs

Engineering Contradiction:

Improvefabrication simplicityVSAvoidnoise interference

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a shield layer as an intermediary between the Vcom layer and the column traces. This shield layer acts as a mediator that blocks electromagnetic noise from the Vcom layer from coupling into the sensitive column traces, thereby eliminating noise interference while maintaining a manufacturable structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful electromagnetic field from the Vcom layer into a beneficial shielding opportunity by positioning the shield layer to specifically block noise coupling paths. The Vcom layer's electromagnetic field, which would normally cause interference, is instead contained and redirected by the shield, transforming the harmful effect into a controlled design feature.

Inventive Principle:

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

3Illumination intensity

If transparent traces are used, then panel transparency is maintained, but conductor thickness is limited

Engineering Contradiction:

Improvepanel transparencyVSAvoidconductor thickness

Core Design Contradiction:

Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent employs composite material structures by combining transparent conductive materials (such as ITO) with metallic shield layers. The transparent traces maintain optical transmission properties, while the added metallic shield layer provides enhanced electromagnetic shielding capabilities without compromising the overall transparency of the touch panel.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different regions: transparent conductive materials are used where optical transmission is critical (the trace paths), while opaque metallic materials are used for the shield layer where electromagnetic shielding is the primary function. This local differentiation of material quality optimizes both transparency and shielding performance.

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 approach reduces the overall size of the sensor panel and prevents noise interference, achieving efficient multi-touch detection while maintaining a uniform appearance.

Implementation Method 1

the row traces can be widened to shield the column traces from a modulated Vcom layer

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

capacitive touch sensor panels can be formed from rows and columns of traces on opposite sides of a dielectric

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11112904B2Double-sided touch-sensitive panel with shield and drive combined layer

Publication Date: 2021.09.07 APPLE INC

AI summary

A multi-touch capacitive touch sensor panel can be created using a substrate with column and row traces formed on either side of the substrate. To shield the column (sense) traces from the effects of capacitive coupling from a modulated Vcom layer in an adjacent liquid crystal display (LCD) or any source of capacitive coupling, the row traces can be widened to shield the column traces, and the row traces can be placed closer to the LCD. In particular, the rows can be widened so that there is spacing of about 30 microns between adjacent row traces. In this manner, the row traces can serve the dual functions of driving the touch sensor panel, and also the function of shielding the more sensitive column (sense) traces from the effects of capacitive coupling.