Touch Sensing Circuit Phase Control for EMI-Resistant Displays
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Solution Overview
Problem
Touch display devices experience degraded touch accuracy due to electromagnetic wave noise emitted by surrounding electronic devices, which affects the performance of both the touch display device and the surrounding electronics.
Innovation Solution
A touch display device and touch sensing circuit are designed to improve resistance to electromagnetic noise by applying load-free driving signals with the same frequency as the touch driving signal but with a phase difference or amplitude difference, effectively lowering the cutoff frequency without adding a capacitor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic noise shielding measures are added to improve touch accuracy, then touch accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies load-free driving signals at the same frequency as the touch driving signal to convert electromagnetic noise (harmful factor) into a beneficial effect. By applying signals with phase differences to gate lines and data lines, the patent creates constructive interference that reinforces the touch driving signal while destructive interference cancels out external electromagnetic noise, thereby improving touch accuracy without adding physical shielding structures
Solution Approach 2:
The patent changes the parameters of existing driving signals by introducing phase differences and amplitude variations. The load-free driving signals are configured with specific phase differences (e.g., 0° to 360°) relative to the touch driving signal, and amplitude ratios (e.g., 0.5 to 2.0 times the touch driving signal amplitude). These parameter changes enable noise cancellation through signal interference without requiring additional hardware components
2Reliability
If a low pass filter with low cutoff frequency is used to remove electromagnetic noise, then electromagnetic noise resistance is improved, but parasitic capacitance increases
Solution Approach 1:
The patent replaces the traditional mechanical/electrical low pass filter structure with a signal processing approach. Instead of using physical capacitors and resistors to create a low pass filter, the patent uses load-free driving signals with specific phase and amplitude characteristics to achieve frequency filtering through signal interference. This substitution eliminates the need for additional capacitor elements that would increase parasitic capacitance while still achieving low cutoff frequency effects for noise removal
3Reliability
If additional capacitor elements are added to lower cutoff frequency, then electromagnetic noise filtering is improved, but device complexity and load increase
Solution Approach 1:
The patent converts the harmful effect of electromagnetic noise into a beneficial filtering mechanism by using load-free driving signals. The signals applied to gate lines and data lines create interference patterns that naturally filter out high-frequency noise without requiring physical capacitor elements. This approach achieves electromagnetic noise filtering while avoiding the increased device complexity and load that would result from adding capacitor components
Solution Approach 2:
The patent enables the existing gate lines and data lines to serve dual functions: driving the display and filtering electromagnetic noise. By applying load-free driving signals to these existing structures, they automatically perform noise filtering through signal interference without requiring separate filtering components. This self-service approach eliminates the need for additional capacitor elements and reduces overall device complexity
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 removing electromagnetic noise and reducing parasitic capacitance, thereby improving the overall immunity to electromagnetic interference without increasing the load on the touch electrodes.
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
applying load-free driving signals with the same frequency as the touch driving signal but with a phase difference or amplitude difference, effectively lowering the cutoff frequency without adding a capacitor element
Data Source
AI summary
A touch display device may include a touch display panel including touch electrodes, data lines, gate lines, sensing lines, and sub-pixels; a data driving circuit connected to the data lines; a gate driving circuit connected to the gate lines; and a touch sensing circuit configured to output a touch driving signal to at least one touch electrode among the touch electrodes through at least one corresponding sensing line among the sensing lines. A first driving signal may be configured to be applied to at least one of the data lines while the touch driving signal is output to the at least one touch electrode. The first driving signal may have a same frequency as the touch driving signal and may have a phase difference from the touch driving signal.