Capacitive Touch Coordinate Detection Using Dynamic Method Switching
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Solution Overview
Problem
Capacitance-type coordinate detecting devices face accuracy issues due to variations in touch methods and finger positions, leading to incorrect coordinate detection when fingers do not directly touch the surface or when the touch area changes.
Innovation Solution
A coordinate detecting device that uses a combination of centroid calculation and curve approximation methods based on capacitance variations to accurately determine the coordinates, switching between methods depending on the state of touch, such as the difference in capacitance between peak and adjacent electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the centroid calculation method is used to determine coordinates based on capacitance variation, then the calculation is simple and fast, but the detection accuracy decreases when the finger does not directly touch the surface or when touch area varies
Solution Approach 1:
The patent dynamically switches between the centroid calculation method and the curve approximation method based on the detected touch state. When the finger directly touches the surface, the centroid method is used for fast calculation. When the finger approaches without direct touch or touch area varies, the curve approximation method is used to maintain accuracy, thus adapting the calculation approach to different operational conditions.
Solution Approach 2:
The patent changes the calculation parameter (method selection) based on the capacitance variation characteristics. By comparing the capacitance variation of the peak electrode with adjacent electrodes, the system determines whether to use centroid coordinates or curve approximation, effectively changing the processing parameter to match the touch state.
2Device complexity
If a single calculation method is used for all touch scenarios, then the device complexity is low, but the detection accuracy varies with different touch methods
Solution Approach 1:
The patent implements a dynamic method selection mechanism that automatically chooses the appropriate calculation method based on real-time capacitance characteristics. This dynamic adaptation maintains low overall complexity while achieving high accuracy across different touch scenarios.
Solution Approach 2:
The system changes the calculation parameter (method selection) based on detected touch conditions. By comparing capacitance variation ratios, the system selects between centroid and curve approximation methods, maintaining simplicity when possible while improving accuracy when needed.
3Ease of operation
If the centroid calculation method is used regardless of touch state, then the processing is consistent and simple, but noise from non-direct touches cannot be effectively filtered
Solution Approach 1:
The patent dynamically adjusts the processing approach based on touch state detection. When non-direct touch is detected through capacitance variation analysis, the system switches to curve approximation method which effectively filters noise, while maintaining centroid method for direct touches to preserve processing consistency.
Solution Approach 2:
The system changes the calculation parameter based on noise characteristics detected in the capacitance data. By analyzing the relationship between peak and adjacent electrode variations, the system selects the appropriate method to maintain processing consistency while improving reliability in different conditions.
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 detection accuracy by adapting to different touch states, reducing errors caused by non-direct touches and varying touch areas, and effectively filters noise to provide precise coordinate calculations.
Implementation Method 1
a detecting unit that detects the capacitance of each electrode
Data Source
AI summary
A coordinate detecting device includes a detecting unit configured to detect the capacitance of each of a plurality of electrodes arranged in a predetermined direction and an arithmetic processing unit configured to calculate the coordinates of a detection target using different calculation methods according to the state of a variation in the capacitance of the plurality of electrodes. The arithmetic processing unit calculates the coordinates of the detection target, using one of a centroid calculation method of calculating the coordinates of the centroid and a curve approximation method of calculating a peak of a curve according to a comparison value between a capacitance variation of a peak electrode and a capacitance variation of an electrode which is not adjacent to the peak electrode.