Touch Driving Signal Generator with Smooth Voltage Transitions
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Solution Overview
Problem
Existing touch display devices generate Electromagnetic Interference (EMI) due to discontinuous voltage levels and unsine wave signals in their driving signals, leading to harmonics.
Innovation Solution
The driving signal generator employs a window function code generator, sine wave code generator, and signal converter to produce a touch driving voltage with gradually increasing or decreasing voltage levels, mimicking a sine wave, thereby reducing harmonics and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discontinuous voltage levels and unsine wave signals are used in driving signals for touch detection and display functions, then the driving signal can be simplified and easier to generate, but Electromagnetic Interference (EMI) and harmonics are generated
Solution Approach 1:
The patent applies parameter changes by transitioning from discontinuous voltage levels to continuous voltage levels that gradually increase or decrease. The driving signal generator uses a signal converter to convert digital codes into analog voltages with smooth transitions, changing the voltage parameter from step-like to continuous, thereby reducing EMI and harmonics while maintaining ease of generation through digital control
Solution Approach 2:
The patent applies the curvature principle by making the voltage waveform resemble a sine wave with smooth continuous changes. Instead of sharp transitions and discontinuous levels, the voltage follows a curved, continuous path that mimics sinusoidal behavior, reducing the abrupt changes that cause EMI and harmonics
2Device complexity
If discontinuous voltage levels are used in driving signals, then the signal generation process is simpler, but harmonics are generated leading to increased EMI
Solution Approach 1:
The patent replaces the mechanical/discrete voltage switching approach with an electronic continuous voltage generation approach. Instead of using simple on/off switching that creates discontinuous levels, the system uses a signal converter that generates continuous voltage waveforms with smooth transitions, substituting the discrete mechanical-like switching with continuous electronic control to eliminate harmonics
3Ease of operation
If unsine wave signals are used for touch detection function, then the signal can be generated more simply, but EMI is generated corresponding to the signal characteristics
Solution Approach 1:
The patent applies dynamics by making the voltage signal adaptive and continuous rather than static and discontinuous. The driving signal generator dynamically adjusts voltage levels in a continuous manner according to the operating mode (display or touch detection), using a signal converter to produce smooth voltage transitions that adapt to different operational requirements while minimizing EMI
Data Source
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.