Display Device Touch Detection Using Equipotential Common Electrode

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Solution Overview

Problem

Current touch sensors in display devices face challenges in achieving high detection accuracy due to parasitic capacitance between touch detection electrodes and common electrodes, which affects the sensitivity of touch detection.

Innovation Solution

The display device incorporates a signal control circuit that synchronizes the touch driving signal with the common electrode's potential during touch detection periods, reducing the electric field and parasitic capacitance between touch detection electrodes and common electrodes, thereby enhancing detection sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a touch sensor is installed on the display screen using a conventional structure, then the user can input information by touching the screen, but parasitic capacitance between touch detection electrodes and common electrodes reduces detection accuracy

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidparasitic capacitance

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies equipotentiality by synchronizing the potential of the common electrode with the touch driving signal during the touch detection period. This creates an equipotential state between the common electrode and the touch detection electrode, eliminating the electric field between them and reducing parasitic capacitance. The signal control circuit adjusts the common electrode's potential to match the touch driving signal potential, thereby minimizing interference and improving touch detection accuracy.

Inventive Principle:

Principle #12Equipotentiality

Solution Approach 2:

The patent changes the potential parameter of the common electrode dynamically. During the touch detection period, the common electrode's potential is changed to synchronize with the touch driving signal, while during non-detection periods, it maintains its original potential for display functions. This parameter change approach allows the system to optimize touch detection performance without compromising display operation.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the common electrode potential is adjusted to reduce parasitic capacitance, then touch detection sensitivity improves, but display luminance or operational frequency may be compromised

Engineering Contradiction:

Improvedetection sensitivityVSAvoiddisplay luminance and operational frequency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent implements periodic action by dividing the operation into distinct periods: touch detection periods where the common electrode potential synchronizes with the touch driving signal to improve detection sensitivity, and non-detection periods where the common electrode maintains its original potential for normal display operation. This periodic switching allows the system to optimize for touch detection only when needed, without continuously compromising display performance.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent introduces dynamics by making the common electrode's potential adjustable and time-dependent. The potential is dynamically changed based on the operational mode (touch detection vs. normal display), allowing the system to adapt to different requirements. The signal control circuit enables this dynamic adjustment, ensuring optimal performance for the current operational phase while maintaining overall system reliability.

Inventive Principle:

Principle #15Dynamics

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 improves the detection sensitivity of touch events by minimizing parasitic capacitance, leading to more accurate touch detection without compromising the display's luminance or operational frequency.

Implementation Method 1

parasitic capacitance between touch detection electrodes and common electrodes

Methodology Applied

Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 2

reducing the electric field and parasitic capacitance between touch detection electrodes and common electrodes

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS11494020B2Display device

Publication Date: 2022.11.08 MAGNOLIA WHITE CORP

AI summary

A display device comprises a first power supply line supplying a first potential, a second power supply line supplying a second potential, a third power supply line supplying a touch driving signal, and a display unit including a plurality of sub-pixels. The display unit comprises a plurality of first electrodes respectively provided in the plurality of sub-pixels and electrically connected to the first power supply line, a second electrode provided to be common among the plurality of sub-pixels and electrically connected to the second power supply line, a light emitting layer provided between the first electrode and the second electrode, a plurality of third electrodes electrically connected to the third power supply line, and a signal control circuit supplying a signal synchronized with a touch driving signal to the second electrode in a period in which a touch driving signal is supplied to the plurality of third electrodes.