Touch Sensing Circuit Using Load-Free Signals Against EMI Noise
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Solution Overview
Problem
Touch display devices experience degraded accuracy due to electromagnetic noise from surrounding electronic devices, which existing technologies fail to effectively mitigate without adding capacitor elements.
Innovation Solution
A touch display device and touch sensing circuit that employs load-free driving signals with phase and amplitude differences to reduce parasitic capacitance, forming a low-pass filter that increases the cutoff frequency and improves immunity to electromagnetic noise without using additional capacitor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic noise shielding is implemented using conventional methods (adding capacitor elements), then immunity to electromagnetic noise is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional capacitor elements by utilizing the inherent parasitic capacitance of existing display elements (liquid crystal layers, electrodes, insulation films) as the filtering capacitance. This removes unnecessary components while maintaining electromagnetic noise immunity.
Solution Approach 2:
The display elements themselves serve dual functions: displaying images and providing electromagnetic noise filtering through their inherent parasitic capacitance. The liquid crystal layer and insulation films automatically function as filtering capacitors without requiring separate components.
2Reliability
If the cutoff frequency of the low-pass filter is lowered to improve electromagnetic noise immunity, then immunity to electromagnetic noise is improved, but response speed of the touch display device deteriorates
Solution Approach 1:
The patent optimizes the capacitance value of the filtering capacitor to achieve an optimal balance between cutoff frequency and response speed. By carefully selecting the capacitance value within a specific range, the system maintains both electromagnetic noise immunity and fast response characteristics.
Solution Approach 2:
The system dynamically adjusts operating parameters (such as driving voltage and frequency) to optimize performance under different conditions, allowing the cutoff frequency and response speed to be simultaneously optimized for specific application scenarios.
3Reliability
If parasitic capacitance is increased to lower cutoff frequency for better noise filtering, then immunity to electromagnetic noise is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent extracts and utilizes the parasitic capacitance that already exists in the display structure (from liquid crystal layers, insulation films, and electrode overlaps) as the filtering capacitance. This eliminates the need for separate capacitor components and reduces manufacturing complexity.
Solution Approach 2:
The insulation films and liquid crystal layers serve multiple functions: electrical insulation, liquid crystal containment, and electromagnetic noise filtering through their parasitic capacitance. This multi-functionality reduces the number of components and simplifies manufacturing.
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
The solution enhances touch accuracy by effectively removing electromagnetic noise and improving immunity to electromagnetic interference, thereby increasing the overall sensitivity of the touch display device.
Implementation Method 1
a touch sensing circuit configured to output a pulse type touch driving signal to at least one of the plurality of touch electrodes
Implementation Method 2
employs load-free driving signals with phase and amplitude differences to reduce parasitic capacitance
Implementation Method 3
forming a low-pass filter that increases the cutoff frequency and improves immunity to electromagnetic noise
Data Source
AI summary
Embodiments of the present disclosure relate to a touch display device and a touch sensing circuit that apply a load-free driving signal having a phase difference or amplitude difference from the touch driving signal to a touch display panel. According to embodiments of the present disclosure, electromagnetic noise immunity may be improved and touch accuracy may be increased. The touch sensing circuit comprises: a touch driving circuit configured to output a pulse type touch driving signal to at least one of a plurality of touch electrodes disposed on a touch display panel; and a load-free driving signal output circuit configured to output at least one load-free driving signal having a frequency equal to a frequency of the touch driving signal and having a phase difference or amplitude difference from the touch driving signal.