Touch Sensing Unit Multiplexer Arrangement for Display Panel Noise Reduction

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Solution Overview

Problem

As display devices increase in size, the mutual capacitance method for touch sensing leads to RC delays, making touch sensing less reliable, and the self-capacitance method faces space constraints and signal interference issues, resulting in noise and increased bezel area.

Innovation Solution

The implementation of a display device with a touch sensing unit that utilizes the self-capacitance method, incorporating a multiplexer and strategically arranging sensing channels, gate control lines, and power voltage lines to minimize dead space and reduce noise by spacing signal lines apart.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mutual capacitance method is used for touch sensing in large display devices, then touch sensing can be implemented, but RC delays occur leading to less reliable touch sensing

Engineering Contradiction:

Improvetouch sensing reliabilityVSAvoidRC delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts the touch sensing function from the traditional mutual capacitance method and implements it using the self-capacitance method instead. By taking out the problematic mutual capacitance sensing mechanism and replacing it with self-capacitance sensing, the patent eliminates the RC delay issue while maintaining touch sensing functionality in large display devices.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental sensing parameter from mutual capacitance (interaction between two electrodes) to self-capacitance (single electrode capacitance to ground). This parameter change fundamentally alters the sensing mechanism to avoid RC delays associated with mutual capacitance in large displays, while still enabling accurate touch detection.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the self-capacitance method is used for touch sensing, then RC delay issues are avoided, but space constraints and signal interference occur leading to increased dead space and bezel area

Engineering Contradiction:

Improvetouch sensing reliabilityVSAvoiddead space and bezel area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the touch sensing signal lines with the existing display driver line structure. By combining the functions of display driving and touch sensing within the same line infrastructure, the patent eliminates the need for separate dedicated touch sensing lines, thereby reducing dead space and minimizing the increase in bezel area.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the driver lines serve multiple functions: both display pixel driving and touch sensing signal transmission. This multi-functionality approach allows the same physical infrastructure to support both display and touch operations, reducing the overall space required and minimizing bezel area expansion.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If signal lines are arranged closely to minimize dead space, then area is reduced, but noise interference increases

Engineering Contradiction:

Improvedead spaceVSAvoidnoise interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces ground lines as intermediary elements between the sensing signal lines and power voltage lines. These ground lines act as shields that electrically isolate the sensitive touch sensing signals from noisy power lines, reducing noise interference while allowing compact arrangement of all lines to minimize dead space.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful noise from power voltage lines into a beneficial shielding effect by strategically placing ground lines. The ground lines absorb or redirect electromagnetic interference, transforming the noisy environment into a protected sensing zone, thereby enabling close line arrangement without sacrificing signal quality.

Inventive Principle:

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

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 sensing reliability and reduces noise interference, maintaining accurate touch detection while minimizing dead space and bezel area, even in larger display devices.

Implementation Method 1

Many such touch sensors utilize a mutual capacitance method or a self-capacitance method. The mutual capacitance method senses a touch by identifying a change in capacitance between two conductive layers of a plurality of touch electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11797115B2Display device including a touch sensing unit

Publication Date: 2023.10.24 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a display panel including pixels and a scan driver for driving the pixels. The pixels are in a display area and the scan driver is in a non-display area. A touch sensing unit is disposed on the display panel and includes touch electrodes disposed in a sensing area and touch sensing lines connected to the touch electrodes. The non-display area includes at least one multiplexer, the touch sensing lines are electrically connected to input terminals of the at least one multiplexer through touch contact holes formed on the display panel. Sensing channels electrically connected to output terminals of the multiplexer are parallel to the scan driver. The at least one multiplexer is disposed between the sensing channels and the scan driver.