Display Device Touch Sensing Coupling Capacitance Detection

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Solution Overview

Problem

The integration of touch sensing units with display devices often leads to image distortion and reduced touch sensitivity due to coupling capacitance between the display unit and the touch sensing unit, which affects the quality of both image display and touch input recognition.

Innovation Solution

A display device design that includes a touch sensing unit with driving and sensing electrodes, a display driver, and a control unit to detect and quantify coupling capacitance between the display unit and the touch sensing unit by supplying touch driving signals and receiving touch sensing signals, allowing for the identification of degradation points in the common electrode and driving voltage line, thereby reducing or preventing coupling capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a touch sensing unit is integrated with the display device, then touch input recognition capability is improved, but coupling capacitance between the display unit and touch sensing unit causes image distortion and reduced touch sensitivity

Engineering Contradiction:

Improvetouch input recognition capabilityVSAvoidimage quality and touch sensitivity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extracts and identifies the coupling capacitance problem by separating the touch sensing unit from the display unit for independent measurement. The test mode allows the touch sensing unit to be measured independently by disconnecting or isolating it from the display unit, enabling identification of degradation points in the common electrode and driving voltage line that cause coupling capacitance issues.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the operational parameters of the display device by introducing a test mode that switches the connection state of the touch sensing unit. In normal mode, the touch sensing unit operates with the display unit; in test mode, the touch sensing unit is disconnected or isolated, allowing measurement of coupling capacitance effects and identification of degradation points through parameter comparison.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the display device operates in normal mode with both display and touch functions, then full functionality is achieved, but coupling capacitance degrades performance; if test mode is activated to measure coupling capacitance, then degradation points can be identified, but normal operation is interrupted

Engineering Contradiction:

Improveperformance monitoring capabilityVSAvoidoperational continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements periodic action by allowing the display device to switch between normal operation mode and test mode. The control unit can periodically activate the test mode to measure coupling capacitance and identify degradation points, then return to normal mode for full functionality. This periodic testing enables performance monitoring while maintaining operational continuity over time.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The display device performs self-diagnosis and self-monitoring by incorporating the test mode that allows it to automatically detect coupling capacitance degradation points. The system serves itself by identifying performance issues without external intervention, enabling proactive maintenance and optimization of touch sensitivity and image quality.

Inventive Principle:

Principle #25Self-service

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 enables the detection and quantification of capacitance degradation, improving image quality and touch sensitivity by minimizing coupling capacitance between the display and touch sensing units, thus enhancing overall device performance.

Implementation Method 1

The touch sensing unit determines whether a users touch input is received, and calculates the coordinates of the position of a touch input

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

images may be distorted and thus image quality and touch sensitivity may deteriorate due to coupling capacitance between the display unit and the touch sensing unit

Methodology Applied

Scientific EffectCoupling capacitance: Parasitic Capacitance

Data Source

PatentUS11513629B2Display device

Publication Date: 2022.11.29 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a plurality of pixels. A gate line extends in a first direction and is connected to each of the plurality of pixels. A common electrode is disposed above the gate line and extends across the plurality of pixels. A touch sensing unit is disposed above the common electrode and includes a plurality of driving electrodes and a plurality of sensing electrodes. A display driver drives the plurality of pixels. A first fan-out line is connected to the display driver. A touch driver drives the driving electrodes and the sensing electrodes. A second fan-out line is connected to the touch driver. A first switching element selectively connects one of the first fan-out line and the second fan-out line to the gate line.