Touch Sensor Shielding via TFT Conductive Electrodes

Solution Overview

Problem

Input devices with larger sensor devices and display screens face increased settling time due to the use of inactive transmitter electrodes for shielding, which also increases capacitive load and interferes with touch sensing.

Innovation Solution

The input device uses conductive electrodes within the thin-film-transistor (TFT) layer of the display screen to shield against interference during touch sensing by driving source lines to a level and electrically floating inactive transmitter electrodes, reducing capacitive load and settling time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If inactive transmitter electrodes are used for shielding, then interference is reduced, but settling time increases and capacitive load increases

Engineering Contradiction:

ImproveinterferenceVSAvoidsettling time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent extracts the shielding function from the transmitter electrodes and relocates it to the conductive electrodes within the TFT layer. By taking out the shielding task from the transmitter electrodes, the original electrodes can be electrically floated during sensing operations, removing their capacitive load while dedicated conductive electrodes provide the necessary shielding against interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces conductive electrodes within the TFT layer as an intermediary element that performs the shielding function. These intermediary conductive electrodes mediate between the need for interference protection and the requirement to reduce capacitive load, allowing the transmitter electrodes to be floated while maintaining effective shielding through the intermediate conductive layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If inactive transmitter electrodes are used for shielding, then interference is reduced, but capacitive load increases

Engineering Contradiction:

ImproveinterferenceVSAvoidcapacitive load

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent extracts the shielding function from the transmitter electrodes and relocates it to the conductive electrodes within the TFT layer. By taking out the shielding task from the transmitter electrodes, the original electrodes can be electrically floated during sensing operations, removing their capacitive load while dedicated conductive electrodes provide the necessary shielding against interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces conductive electrodes within the TFT layer as an intermediary element that performs the shielding function. These intermediary conductive electrodes mediate between the need for interference protection and the requirement to reduce capacitive load, allowing the transmitter electrodes to be floated while maintaining effective shielding through the intermediate conductive layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If larger sensor devices and display screens are used, then display resolution and size are improved, but settling time increases

Engineering Contradiction:

Improvedisplay screen sizeVSAvoidsettling time

Core Design Contradiction:

Area of stationary objectVSLoss of time

Solution Approach 1:

The patent extracts the shielding function from the transmitter electrodes and relocates it to the conductive electrodes within the TFT layer. By taking out the shielding task from the transmitter electrodes, the original electrodes can be electrically floated during sensing operations, removing their capacitive load while dedicated conductive electrodes provide the necessary shielding against interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces conductive electrodes within the TFT layer as an intermediary element that performs the shielding function. These intermediary conductive electrodes mediate between the need for interference protection and the requirement to reduce capacitive load, allowing the transmitter electrodes to be floated while maintaining effective shielding through the intermediate conductive layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively shields against interference while reducing the settling time of the sensor device, enabling faster and more accurate touch sensing, even in larger and higher-resolution displays.

Implementation Method 1

a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

drive the first transmitter electrode with a transmitter signal for capacitive sensing

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS9594458B2Shielding with display elements

Publication Date: 2017.03.14 SYNAPTICS INC

AI summary

A method and apparatus for operating an input device having a touch sensor and associated display device is discussed. While performing touch sensing, inactive transmitter electrodes of the touch sensor are electrically floated, and one or more source lines from the display device are operated to achieve shielding against interference, such as that coming from a backlight underneath the touch sensor.