In-Cell Touch Display Voltage Modulation Against Parasitic Capacitance
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Solution Overview
Problem
The integration of an in-cell touch sensor in an organic light emitting diode display panel increases parasitic capacitance, degrading touch sensitivity and image quality due to the proximity of touch and display electrodes.
Innovation Solution
A design that modulates power and gate voltages to maintain consistent voltage differences between touch and display electrodes, reducing parasitic capacitance and enhancing touch sensitivity through a time-division driving method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an in-cell touch sensor is embedded in the display panel, then the device thickness is reduced and manufacturing is simplified, but parasitic capacitance increases significantly degrading touch sensitivity
Solution Approach 1:
The patent applies dynamic voltage modulation to the touch electrodes and display driving electrodes through a control circuit. By dynamically adjusting the voltage levels in a time-division manner, the control circuit maintains optimal voltage differences that minimize parasitic capacitance effects while enabling touch sensing functionality within the thin panel structure.
Solution Approach 2:
The patent changes the voltage parameters of the touch electrodes and display driving electrodes by applying different voltage levels at different time periods. This parameter modulation approach allows the system to reduce parasitic capacitance impact on touch sensitivity while maintaining the integrated in-cell structure benefits.
2Device complexity
If touch electrodes are placed close to display driving electrodes and lines, then the in-cell integration is achieved, but parasitic capacitance between touch sensor and display driving components increases
Solution Approach 1:
The patent extracts and separately controls the voltage signals for touch electrodes and display driving electrodes through a dedicated control circuit. By taking out the voltage control function and managing it independently through time-division multiplexing, the system can mitigate parasitic capacitance effects while maintaining the physical integration benefits.
Solution Approach 2:
The patent implements periodic voltage modulation where touch electrode voltage and display driving electrode voltage are applied in alternating time periods. This periodic action allows the system to minimize parasitic capacitance interference by ensuring that both electrodes are not at high voltage simultaneously, thereby reducing capacitive coupling effects.
3Measurement precision
If voltage differences between touch and display electrodes are large, then touch sensing capability is improved, but image quality degrades due to parasitic capacitance effects
Solution Approach 1:
The control circuit dynamically adjusts voltage levels based on operational mode - applying higher voltage differences during touch sensing periods and reducing voltage differences during display periods. This dynamic adaptation allows the system to optimize touch sensing capability when needed while minimizing parasitic capacitance effects on image quality during display operation.
Solution Approach 2:
The patent uses periodic time-division multiplexing where touch sensing operations and display operations are separated into different time periods. During touch sensing periods, larger voltage differences are applied to touch electrodes for improved sensitivity, while during display periods, voltage levels are adjusted to minimize parasitic capacitance impact on image 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
Improves touch sensitivity and accuracy while reducing panel thickness and minimizing image quality degradation by mitigating parasitic capacitance effects.
Implementation Method 1
a plurality of touch electrodes formed in a transistor formation layer in which the thin film transistor is formed to form a coupling capacitor with a cathode electrode of the light emitting element
Implementation Method 2
the possibility that a parasitic capacitance between the touch sensor and the display driving electrode or a parasitic capacitance between the touch sensor and the display driving line increases
Data Source
AI summary
The present disclosure provides an in-cell touch display device in which an in-cell touch sensor technology can be implemented in an organic light emitting diode display panel. An in-cell touch display device may include a substrate, a transistor formation layer formed on the substrate and including a semiconductor, a source electrode, a drain electrode, and a gate electrode, and a light emitting element layer formed on the transistor formation layer and including an anode electrode, an emission layer, and a cathode electrode, and wherein a plurality of touch electrodes forming a coupling capacitor with the cathode electrode of the light emitting element layer may be formed in the transistor formation layer.