Phase-tagged Capacitance Sensing Circuit for Noise-Resistant Touch Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional touch panels face challenges in accurately determining touch positions due to noise interference and require complex phase compensation, leading to delayed response times and increased costs.
Innovation Solution
The implementation of a touch panel system that uses phase information pulses on driving signals to generate demodulation signals, allowing for noise reduction and accurate sensing value determination without the need for phase compensation, utilizing orthogonal vectors to filter out noise and improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase compensation is performed to improve measurement precision, then measurement precision is improved, but response time increases and device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing phase information pulses during the driving signal periods before actual touch detection. The phase information pulses are generated in advance and stored, eliminating the need for real-time phase compensation calculations during touch events, thus improving response time while maintaining measurement precision
Solution Approach 2:
The patent implements periodic action by generating phase information pulses at regular intervals corresponding to the driving signal periods. The phase information is updated periodically and stored for subsequent use, allowing the system to maintain accurate phase data without continuous real-time processing, thereby reducing response time while preserving measurement accuracy
2Measurement precision
If phase compensation is performed to improve measurement precision, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent simplifies device complexity by performing phase compensation in advance and storing the results as phase information pulses. This eliminates the need for complex real-time phase compensation circuitry during touch detection, reducing device complexity while maintaining measurement precision through pre-computed phase data
Solution Approach 2:
The patent uses copying by creating phase information pulses that replicate the phase characteristics of the driving signal. Instead of performing complex phase compensation operations, the system copies phase information into pulse form that can be directly used for accurate touch detection, simplifying the overall device architecture
3Object-affected harmful factors
If noise filtering is applied to reduce noise interference, then noise interference is reduced, but response time increases
Solution Approach 1:
The patent extracts and separates phase information from the driving signal into distinct phase information pulses. By extracting the essential phase data beforehand, the system eliminates the need for time-consuming noise filtering operations during actual touch detection, reducing noise interference while maintaining fast response times
Solution Approach 2:
The patent replaces traditional mechanical or analog noise filtering systems with a digital signal processing approach using phase information pulses. This substitution allows for efficient noise rejection through digital demodulation without the time delays associated with analog filtering circuits, reducing both noise interference and response 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 approach enhances the accuracy of touch position detection, reduces noise interference, and simplifies the circuit design, resulting in faster response times and lower costs.
Implementation Method 1
when a user presses down a capacitive touch-panel 11 with his finger, the capacitance between two electrodes is affected due to the transmission characteristics of the human body, and the value of capacitance between the two electrodes is altered
Data Source
AI summary
An electronic device includes a touch panel, a driving circuit, and a sensing circuit. The driving circuit generates a driving signal, and superposes phase information on the driving signal. The touch panel includes multiple crossing conductors, for providing a sensing signal in response to a contact of an object on one of the sensing conductors and to a driving signal applied on the sensing element. The sensing circuit includes a signal extractor and a tag detector. The signal extractor generates a demodulation signal based on the period of the driving signal, width of the phase information, and for demodulating the sensing signal by using the demodulation signal to determine a sensing value. The tag detector enables the signal extractor as soon as a magnitude of the sensing signal is over a predetermined threshold. The signal demodulates the sensing signal by using a demodulation signal whose period is the same as the driving signal to determine the sensing value. The present electronic device can determine a touch position by processing of analog signal using the demodulation signal without phase compensation.