Capacitive Touch Screen Calibration via Reference Capacitance Difference
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Solution Overview
Problem
Capacitive touch screens face challenges in accurately calibrating reference capacitance values due to external interference and environmental changes, leading to potential operation failures.
Innovation Solution
A method that determines the reference capacitance value of a capacitive touch screen by calculating differences between backup and temporary reference capacitance values using preset thresholds, allowing for accurate calibration and avoiding direct calibration during power-up, which helps in stabilizing the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch screen uses traditional calibration methods to obtain reference capacitance values, then the calibration process is simple, but the calibration accuracy deteriorates due to external interference and environmental changes
Solution Approach 1:
The patent performs preliminary calibration actions by obtaining reference capacitance values at multiple specific moments (initial calibration moment and multiple subsequent calibration moments) before normal operation begins. This preliminary multi-point calibration establishes a baseline that accounts for environmental variations and interference, improving accuracy without complicating the actual usage process.
Solution Approach 2:
The patent implements feedback by continuously monitoring capacitance changes and comparing them against the established reference values. When capacitance changes exceed predetermined thresholds, the system identifies touch operations and adjusts the reference capacitance values accordingly. This feedback mechanism maintains calibration accuracy while adapting to environmental changes and interference.
2Reliability
If the touch screen forcibly updates reference capacitance values when capacitance changes persist for a specific duration, then the calibration responds to foreign matter removal, but the reliability deteriorates due to wrong calibration from intentional hand touches
Solution Approach 1:
The patent uses feedback mechanisms to distinguish between foreign matter removal and intentional hand touches. By monitoring the duration and pattern of capacitance changes against predetermined thresholds, the system can identify when a user intentionally touches the screen during calibration and prevents erroneous updates. This maintains calibration reliability while preserving normal operational simplicity.
Solution Approach 2:
The patent establishes preliminary reference capacitance values at multiple specific moments before normal operation begins. These preliminary values serve as a baseline that helps distinguish between temporary changes (like foreign matter) and sustained changes (like intentional touches). By comparing current measurements against this pre-established baseline, the system can reliably determine when to update calibration values.
3Measurement precision
If the touch screen uses proportion of positive to negative capacitance change values for calibration, then the calibration can handle touch area pressing, but the measurement precision deteriorates due to difficulty in defining thresholds and influence from nearby conductors
Solution Approach 1:
The patent implements feedback by continuously monitoring capacitance changes and comparing them against reference values obtained at specific moments. When changes exceed predetermined thresholds, the system identifies and adjusts for touch operations. This feedback approach provides precise calibration without requiring complex algorithms to define proportions or handle nearby conductors, as the reference values are established before such interference occurs.
Solution Approach 2:
The patent performs preliminary calibration by obtaining reference capacitance values at an initial moment and multiple subsequent moments before normal operation. This preliminary action establishes a clean baseline that is not influenced by nearby conductors or complex touch patterns. By using these pre-established reference values, the system achieves precise calibration without needing to define complex thresholds or algorithms for handling interference.
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 method ensures accurate calibration of capacitive touch screens by accounting for environmental changes and interference, reducing the likelihood of operation failures and improving touch screen reliability.
Implementation Method 1
A capacitive touch screen determines whether there is a touch operation according to the change of capacitance on the touch screen
Data Source
AI summary
A method for calibration of a capacitive touch screen and a capacitive touch apparatus are disclosed. The calibration method includes obtaining a temporary reference capacitance value of a touch detection point of the capacitive touch screen when the capacitive touch screen powers up. A first difference between a backup reference capacitance value of the touch detection point and the temporary reference capacitance value of the touch detection point is obtained and a reference capacitance value of the touch detection point is determined according to the first difference and a first preset threshold.