Touch Display Signal Conversion Circuit Parasitic Capacitance Reduction
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Solution Overview
Problem
The integration of touch sensors within display panels poses technical challenges due to increased parasitic capacitance, which affects touch sensitivity and image quality, and existing methods complicate manufacturing and increase device thickness.
Innovation Solution
A touch display device with a signal conversion circuit that generates load-free driving signals with constant voltage differences to reduce parasitic capacitance between touch electrodes and driving patterns, using a power supply circuit to output modulation power signals that match the voltage patterns of display driving signals during touch operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a touch sensor is embedded within a display panel, then the device thickness is reduced and manufacturing is simplified, but parasitic capacitance between touch electrodes and driving patterns increases, degrading touch sensitivity and image quality
Solution Approach 1:
The patent applies equipotentiality by making the driving pattern voltage track the touch electrode voltage during touch operations. The signal conversion circuit converts display driving signals to match the voltage waveform of touch driving signals, ensuring that the driving pattern and touch electrode maintain the same potential variations. This eliminates voltage differences between adjacent conductors, thereby preventing parasitic capacitance from affecting touch sensing accuracy.
Solution Approach 2:
The patent changes the voltage parameter of the driving pattern dynamically to match the touch electrode voltage. The signal conversion circuit adjusts the driving signal voltage waveform to correspond with the touch driving signal voltage waveform, transforming the driving pattern from a static voltage reference to a dynamic voltage follower that adapts to touch operation requirements.
2Area of stationary object
If touch electrodes are positioned close to display driving electrodes, then the display area is maximized, but parasitic capacitance increases causing decreased touch sensitivity
Solution Approach 1:
By making the driving pattern voltage track the touch electrode voltage, the patent creates an equipotential condition between closely spaced conductors. This eliminates the voltage difference that would otherwise create parasitic capacitance effects, allowing touch electrodes to be positioned close to display driving electrodes without degrading touch sensitivity.
3Loss of energy
If voltage variations of power signals occur during touch driving period, then power efficiency is improved, but image quality and touch sensing accuracy are impaired
Solution Approach 1:
The signal conversion circuit ensures that even when power signal voltages vary for power efficiency, the driving pattern voltage continuously tracks the touch electrode voltage. This maintains equipotential conditions between adjacent conductors, preventing parasitic capacitance variations that would otherwise degrade image quality and touch sensing accuracy during the touch driving period.
Data Source
AI summary
A touch display device can include a display panel including a plurality of data lines, a plurality of gate lines, a plurality of subpixels, and a plurality of touch electrodes, each of the plurality of subpixels including a light emitting element and a driving transistor; and a signal conversion circuit configured to supply a driving signal to the plurality of subpixels in the display panel or a driving circuit connected to the display panel. Also, the driving signal can have a signal waveform corresponding to a signal waveform of a first power signal or a signal waveform of a second power signal.