Driving Signal Generator Using Windowed Sine Waves to Reduce EMI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch display devices generate Electromagnetic Interference (EMI) due to discontinuous voltage levels and un-sine wave signals in their driving signals, which are not effectively addressed by current technologies.
Innovation Solution
The driving signal generators employ a combination of window function, sine wave, and voltage shifting code generators, along with operation circuits and signal converters to generate touch driving voltages with gradually increasing or decreasing levels, mimicking sine waves and reducing harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If discontinuous voltage levels and un-sine wave signals are used in driving signals, then device complexity is reduced, but Electromagnetic Interference (EMI) increases
Solution Approach 1:
The patent applies curvature by transforming discontinuous voltage levels into smooth sine wave signals. The driving signal generator uses sine wave code generators and window function code generators to create continuous, curved voltage transitions instead of abrupt steps, thereby reducing electromagnetic interference while maintaining functional simplicity
Solution Approach 2:
The patent changes the voltage parameter from discontinuous levels to continuous sine wave variations. By modulating the voltage according to sine wave patterns and window functions, the system achieves smoother transitions that reduce harmonics and EMI without significantly increasing device complexity
2Ease of manufacture
If discontinuous voltage levels are used in driving signals, then signal generation is simpler, but harmonics increase
Solution Approach 1:
The patent replaces abrupt voltage transitions with smooth curved sine wave patterns. This curvature in the voltage waveform eliminates sharp edges that generate harmonics, while the signal generation process remains manageable through programmed code generators that produce the sine wave patterns
3Speed
If voltage level transitions are abrupt, then switching speed is faster, but Electromagnetic Interference (EMI) increases
Solution Approach 1:
The patent applies curvature to voltage transitions by using sine wave patterns instead of abrupt steps. The sine wave provides continuous, smooth transitions that eliminate the sharp edges responsible for EMI, while still achieving efficient voltage changes through the periodic nature of the wave
Solution Approach 2:
The patent uses periodic sine wave action to achieve voltage transitions. Instead of single abrupt changes, the voltage varies periodically following sine wave patterns, which distributes the transition energy over time and reduces peak EMI generation while maintaining effective switching capability
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A driving signal generator includes a window function code generator, a sine wave code generator, an operation circuit and a signal converter. The window function code generator generates a first code corresponding to a window of a first sine wave. The sine wave code generator generates a second code corresponding to a second sine wave, wherein a frequency of the second sine wave is higher than a frequency of the first sine wave. The operation circuit is coupled to the window function code generator and the sine wave code generator, and performs an operation on the first code and the second code to generate an output code. The signal converter is coupled to the operation circuit and generates a touch driving voltage of a driving signal by converting the output code.