In-Cell OLED Touch Display With Capacitance-Reducing Power Modulation
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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
The in-cell touch display device incorporates a power modulation circuit that modulates power voltages to equalize the cycle and amplitude of touch and display electrodes, reducing parasitic capacitance and enhancing touch sensitivity by reading charges from the finger capacitor independently of parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
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 divides the electrode structure into functionally independent segments: the anode electrode is separated from the cathode electrode by the emission layer, and the touch electrode is further segmented from display driving electrodes by spatial separation and insulation layers. This segmentation prevents parasitic capacitance coupling between touch and display functions while maintaining integration benefits.
Solution Approach 2:
The patent introduces intermediary elements including insulation layers between the touch electrode and display driving electrodes, and the emission layer as an intermediary between anode and cathode electrodes. These intermediaries act as electrical isolators that prevent parasitic capacitance formation while allowing the integrated structure to function.
2Volume of moving object
If the touch electrode is placed close to display driving electrodes, then the device structure is compact, but parasitic capacitance between touch sensor and display driving electrode increases
Solution Approach 1:
Insulation layers are positioned as intermediary elements between the touch electrode and display driving electrodes, maintaining compact spacing while preventing direct electrical coupling that would generate parasitic capacitance. The emission layer similarly acts as an intermediary barrier.
Solution Approach 2:
The patent applies different local properties to different regions: insulation materials are applied specifically in regions where touch electrodes proximity to display driving electrodes, creating localized electrical isolation where needed while maintaining conductivity in other regions for normal device operation.
3Volume of moving object
If the touch electrode is placed close to display driving lines, then the device structure is compact, but parasitic capacitance between touch sensor and display driving line increases
Solution Approach 1:
Insulation layers are positioned between touch electrodes and display driving lines to prevent direct electrical coupling. These intermediary insulation structures allow compact routing of driving lines near touch electrodes without generating harmful parasitic capacitance.
4Measurement precision
If power voltages are modulated to equalize cycle and amplitude, then parasitic capacitance is reduced and touch sensitivity is enhanced, but device complexity increases due to power modulation circuit
Solution Approach 1:
The power modulation circuit is merged with the existing display driving circuitry, using the same voltage supply and control structures to modulate both display and touch electrode voltages. This integration minimizes additional complexity while achieving the benefit of reduced parasitic capacitance through synchronized voltage modulation.
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 touch sensitivity and accuracy by minimizing the impact of parasitic capacitance, maintaining image quality, and enabling touch recognition in organic light emitting diode display panels without separate touch electrodes.
Implementation Method 1
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 can be increased significantly
Implementation Method 2
reading charges from the finger capacitor independently of parasitic capacitance
Data Source
AI summary
An in-cell touch display device is presented herein in which an in-cell touch sensor technology can be implemented in an organic light emitting diode display panel. The in-cell touch display device may include a substrate, a transistor formation layer on the substrate, the transistor formation layer including a semiconductor, a source electrode connected to the semiconductor, a drain electrode connected to the semiconductor, a gate electrode that overlaps the semiconductor, and a plurality of touch lines, and a light emitting element layer on the transistor formation layer, the light emitting element layer including an anode electrode, an emission layer on the anode electrode, a cathode electrode on the emission layer, and a bank layer on a portion of the anode electrode. The cathode electrode is connected to the plurality of touch lines, and the touch lines are closer to the cathode electrode than to the source and drain electrodes.