Capacitance Sensing Circuit With Noise-Phase Touch Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touch technology is susceptible to electromagnetic interference from nearby devices, such as liquid crystal display modules and charging modules, which affects the accuracy of touch event detection in capacitance sensing circuits.
Innovation Solution
A capacitance sensing circuit that generates an input signal based on the phase of noise, using a phase detection unit, phase calculation unit, and waveform generator to minimize the energy associated with noise in the output signal, thereby reducing interference and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a periodic input signal with specific frequency is applied to the detecting circuit, then the capacitance sensing circuit can calculate the change amount of the detection capacitor by analyzing phase or amplitude of the output signal, but the circuit becomes susceptible to electromagnetic interference from surrounding devices such as liquid crystal display modules and charging modules
Solution Approach 1:
The patent makes the input signal frequency dynamic by continuously tracking and adapting to the noise spectrum. Instead of using a fixed frequency, the system dynamically adjusts the input signal frequency to avoid interfering frequencies from surrounding devices, thereby reducing electromagnetic interference while maintaining touch detection accuracy
Solution Approach 2:
The system changes the frequency parameter of the input signal based on the detected noise characteristics. By analyzing the noise spectrum and selecting an optimal frequency that minimizes interference, the patent dynamically adjusts key parameters to resolve the contradiction between measurement precision and interference susceptibility
2Adaptability or versatility
If the capacitance sensing circuit operates close to liquid crystal display modules or charging modules, then device integration is improved, but electromagnetic interference from these devices negatively impacts the capacitance sensing circuit's ability to judge touch events
Solution Approach 1:
The system performs preliminary noise spectrum analysis before initiating touch detection. By pre-identifying interfering frequencies from surrounding devices and selecting an optimal input signal frequency in advance, the patent ensures reliable touch event judgment even when operating close to liquid crystal display modules or charging modules
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 effectively reduces the influence of noise on the capacitance sensing circuit, improving its overall performance and accuracy in detecting touch events by synchronizing the input signal with noise phases, thus enhancing the reliability of touch event detection.
Implementation Method 1
a phase detection unit for receiving the noise and detecting a first phase of the noise
Implementation Method 2
Capacitive touch technology judges a touch event by sensing the change of capacitance of a detection capacitor in a detecting circuit
Data Source
AI summary
As applied to the field of touch control technology, a capacitance sensing circuit for sensing a detection capacitor of a detecting circuit, includes: a capacitance judging circuit coupled to the detecting circuit for judging the capacitance of the detection capacitor according to the output signal; and an input signal generator coupled to the detecting circuit for generating the input signal according to noise. The input signal generator includes: a phase detection unit for receiving the noise and detecting a first phase of the noise; a phase calculation unit coupled to the phase detection unit for receiving the noise and the first phase and calculating an optimum phase according to the noise and the first phase; and a first waveform generator coupled to the phase calculation unit for generating the input signal according to the optimum phase.