Capacitive Voltage Sensing Circuit for Noise-Resistant Touch Panels
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Solution Overview
Problem
Current capacitive touch panels suffer from noise folding and complex circuitry, leading to affected signal quality and longer update periods due to noise paths and complicated sampling processes.
Innovation Solution
A capacitive voltage information sensing circuit with a mixer and analog filter generates differential signals to isolate noise, and a noise detection circuit using a sampling unit and comparator determines noise presence, eliminating the need for complex capacitor switching and analog buffers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sampling circuits with multiple switches and samplers are used, then signal processing capability is maintained, but noise folding occurs and circuit complexity increases
Solution Approach 1:
The patent extracts and removes the complex sampling circuitry (multiple switches, samplers) from the touch sensing circuit, replacing it with a simplified capacitor voltage sensing approach that directly measures capacitor voltage without requiring complex signal path switching, thereby eliminating noise folding while reducing circuit complexity
Solution Approach 2:
The patent replaces the mechanical/electrical switching system with an electrical measurement system that directly senses capacitor voltage through high-impedance measurement, substituting the need for physical switch-based signal routing with a non-intrusive voltage measurement approach that avoids noise injection
2Reliability
If traditional noise paths with complicated circuits are implemented, then noise filtering capability is provided, but update period increases
Solution Approach 1:
The patent enables the capacitor voltage sensing circuit to inherently filter noise through its high-impedance measurement architecture and direct voltage sensing mechanism, eliminating the need for separate complex noise filtering circuits and associated processing time, thus achieving noise filtering while maintaining fast update rates
Solution Approach 2:
The patent performs noise filtering inherently during the voltage sensing process itself, rather than requiring subsequent separate filtering stages. The high-impedance measurement and direct capacitor voltage detection preemptively eliminate noise before it can propagate through the signal chain, reducing overall processing time
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
This solution effectively eliminates noise, simplifies circuitry, and reduces update periods, improving signal quality and response time in capacitive touch panels.
Implementation Method 1
a mixer, comprising a first input terminal, configured to receive a reference signal; a second input terminal, configured to receive a voltage signal
Implementation Method 2
an analog filter, coupled to the mixer, configured to generate a first low-frequency signal and a second low-frequency signal according to the first differential signal and the second differential signal
Data Source
AI summary
The present disclosure provides a capacitor voltage information sensing circuit. The capacitor voltage information sensing circuit includes a mixer and an analog filter. The mixer includes a first input terminal for receiving a reference signal, a second input terminal for receiving a voltage signal, the voltage signal includes capacitor voltage information and a noise when a touch occurs, a first output terminal for outputting a first differential signal according to the voltage signal and the reference signal, and a second output terminal for outputting a second differential signal according to the voltage signal and the reference signal. The analog filter is coupled to the mixer for generating a first low-frequency signal and a second low-frequency signal according to the first differential signal and second differential signal.