Touch Panel Driving Pulses With RC Compensation for Parasitic Capacitance
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Solution Overview
Problem
The proximity of touch and display panels in touch driving technology leads to the formation of parasitic capacitors, which reduce the sensitivity of touch sensing and require higher voltage levels, compromising the effectiveness of touch driving devices.
Innovation Solution
A touch driving device with separate channel circuits that supply touch driving pulses with curved waveforms based on distinct RC time constants to touch electrodes, using a combination of Pulse Width Modulation (PWM) pulses and auxiliary signals generated by a driving support circuit, to minimize the impact of parasitic capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the touch panel and display panel are located close to each other for user convenience, then the user interface becomes more intuitive and integrated, but parasitic capacitors are formed between the touch electrode and display electrode which lower touch sensing sensitivity
Solution Approach 1:
The patent applies preliminary anti-action by generating a compensation signal before the touch sensing measurement that has the opposite polarity to the parasitic capacitor effect. This compensation signal is applied to the touch electrode to counteract the parasitic capacitance formed between the touch panel and display panel, thereby preventing the sensitivity degradation before it affects the touch sensing accuracy
Solution Approach 2:
The patent changes the electrical parameters by adjusting the voltage levels and waveform characteristics of the driving signals. By modifying the signal parameters (voltage amplitude, pulse width, frequency) and using different RC time constants for different channel circuits, the system compensates for the parasitic capacitance effects while maintaining close proximity between touch and display panels
2Ease of operation
If the touch panel is placed close to the display panel, then integration and user convenience are improved, but the voltage level required for touch driving increases due to parasitic capacitor effects
Solution Approach 1:
The patent changes the signal parameters by using different RC time constants for different channel circuits, adjusting the charging and discharging characteristics of the driving signals. This parameter optimization allows the system to achieve effective touch driving with reduced voltage levels by better matching the signal characteristics to the parasitic capacitance effects
3Measurement precision
If different channel circuits use different RC time constants for curved waveform generation, then parasitic capacitor influence is minimized and touch sensing sensitivity is enhanced, but device complexity increases
Solution Approach 1:
The patent applies local quality by configuring each channel circuit with specific RC time constants tailored to its particular parasitic capacitance characteristics. Different channel circuits have different resistance and capacitance values optimized for their local conditions (different touch electrode positions and surrounding structures), allowing precise compensation without requiring complete redesign of the entire system
Solution Approach 2:
The patent segments the touch driving system into multiple independent channel circuits, each handling specific touch electrodes with dedicated RC networks. This segmentation allows independent optimization of each channel's time constant without affecting other channels, managing complexity through modular design while achieving overall sensitivity enhancement
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
Enhances the sensitivity of touch sensing by reducing the influence of parasitic capacitors and optimizing voltage levels, thereby improving the overall performance of touch driving systems.
Implementation Method 1
a first channel circuit configured to supply a plurality of first touch driving pulses being a curved waveform in accordance with a first RC time constant
Implementation Method 2
a parasitic capacitor is formed between the touch electrode and the display electrode
Data Source
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AI summary
One embodiment provides a touch driving device for driving a touch panel that generates an auxiliary signal using a voltage source and a resistor, and generates a touch driving signal by combining the auxiliary signal and PWM driving pulses. Such touch driving device may change the voltage level of the voltage source or change the resistance value of the resistor to compensate for the characteristic deviation between channel circuits.