Touch Panel Mixer Circuit Noise Removal via Signal Differentiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch panel systems face challenges in precisely detecting touches due to high frequency noise components in sensing signals, which affect the generation of a constant voltage level necessary for accurate touch position determination.
Innovation Solution
A mixer system that employs low pass filtering and signal differentiation to remove high frequency noise components from sensing signals by switching them with reference signals and their phase-inverted counterparts, producing a voltage signal of constant level for precise touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional mixer is used to generate a reference voltage by mixing sensing signals, then the circuit structure remains simple, but high frequency noise components in the sensing signal prevent precise generation of a constant voltage level
Solution Approach 1:
The mixer circuit is segmented into multiple functional modules: first switching unit, first low pass filter, second switching unit, second low pass filter, and adding unit. Each module performs a specific function in the signal processing chain, allowing the complex task of noise removal and voltage generation to be divided into manageable stages that improve precision without overwhelming complexity
Solution Approach 2:
Low pass filtering is applied preliminarily to both the first and second output signals before they are added together. This preliminary noise removal action ensures that high frequency noise components are eliminated early in the processing chain, preventing them from affecting the final voltage level generation and improving measurement precision
2Reliability
If sensing signals with high frequency noise are directly mixed to generate reference voltage, then the processing speed remains fast, but the touch detection accuracy deteriorates due to noise interference
Solution Approach 1:
The harmful high frequency noise components are extracted and removed from the sensing signals through low pass filtering operations. The first low pass filter removes noise from the first output signal, and the second low pass filter removes noise from the second output signal, leaving only the useful low frequency signal components for accurate touch detection
Solution Approach 2:
Low pass filters are introduced as intermediary components between the switching units and the adding unit. These intermediaries selectively pass the useful signal frequencies while blocking the harmful noise frequencies, mediating between the raw sensing signals and the final processed output to ensure reliable touch detection
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 enables precise generation of a voltage level representing the signal intensity difference between sensing and reference signals, enhancing the reliability and accuracy of touch detection in touch panel systems.
Implementation Method 1
a first low pass filter configured to perform low-pass filtering on a first output signal produced from the first switch; a second low pass filter configured to perform low-pass filtering on a second output signal produced from the second switch
Data Source
AI summary
A mixer of a touch panel system includes a first switch configured to switch a sensing signal in accordance with a reference signal; a second switch configured to switch the sensing signal in accordance with a phase-inverted reference signal from the reference signal. Further, the mixer of the touch panel system includes a first low pass filter configured to perform low-pass filtering on a first output signal produced from the first switch; and a second low pass filter configured to perform low-pass filtering on a second output signal produced from the second switch. Furthermore, the mixer of the touch panel system includes a differentiator configured to differentiate signals produced from the first low pass filter and the second low pass filter, to thereby produce a signal of constant level as the sensing signal.