Capacitive Sensing Background Signal Refresh via Frequency Hopping
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Solution Overview
Problem
Capacitive sensing devices face challenges in updating reference values frequently due to increased memory requirements and reduced signal-reading promptness, leading to decreased sensitivity and accuracy in touch manipulation detection as the resolution of the display device increases.
Innovation Solution
A method involving a charge-float-discharge (CFD) cycle and varying numbers of NOP commands to detect capacitance values, with calculations of difference or mean values to determine when to refresh background signals, ensuring timely updates without compromising signal frequency identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the display device is increased (more sensing points), then the sensing precision is improved, but the memory capacity required and update time increase, reducing signal-reading promptness
Solution Approach 1:
The patent segments the sensing points into multiple groups and selectively updates reference values for specific groups based on detected touch patterns. Instead of updating all sensing points uniformly, the system divides them into first sensing points (updated frequently) and second sensing points (updated less frequently), thereby reducing overall update time while maintaining precision where needed.
Solution Approach 2:
The patent implements dynamic update frequency adjustment based on real-time sensing data. The control circuit determines whether to update reference values for different sensing point groups based on detected touch patterns, making the update frequency adaptive rather than static. This dynamic approach optimizes the balance between precision and update speed.
2Measurement precision
If the reference value update frequency is increased, then the detection accuracy is improved, but the signal-reading promptness deteriorates
Solution Approach 1:
The patent segments sensing points into different groups with different update frequencies. First sensing points are updated at a higher frequency to maintain detection accuracy for critical areas, while second sensing points are updated at a lower frequency to preserve signal-reading promptness. This segmented approach resolves the contradiction by applying different update strategies to different spatial regions.
Solution Approach 2:
The patent applies local quality by assigning different update frequencies to different spatial regions (sensing point groups) based on their importance or activity level. Certain regions receive more frequent updates to maintain high detection accuracy, while other regions use less frequent updates to maintain overall system speed, thereby optimizing the local-global trade-off.
3Speed
If the reference value update frequency is decreased, then the signal-reading promptness is improved, but the sensitivity and accuracy of touch manipulation detection deteriorate
Solution Approach 1:
The patent segments sensing points into first and second groups with different update frequencies. By updating first sensing points more frequently than second sensing points, the system maintains detection sensitivity in critical regions while achieving faster overall signal-reading promptness through reduced updates in less critical regions.
Solution Approach 2:
The patent applies partial action by selectively updating only certain sensing point groups rather than all sensing points uniformly. This partial update strategy maintains sufficient detection sensitivity for touch manipulation by updating critical sensing points while avoiding unnecessary updates elsewhere, thereby improving overall signal-reading promptness.
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 speeds up the signal-detection process while maintaining accuracy by determining the optimal timing for refreshing background signals, thus enhancing the sensitivity and efficiency of capacitive sensing devices.
Implementation Method 1
the capacitive sensing device includes sensing points which are defined by X electrodes and Y electrodes and are configured in an array form. When the user touches the capacitive sensing device, a capacitance value of at least a corresponding sensing point on which the user touches changes
Data Source
AI summary
The method for detecting background signals of a capacitive sensing device includes obtaining several capacitance values by detecting a reference point selected from several sensing points in a frequency-hopping manner, and selectively executing a procedure for refreshing the background signals according to the capacitance values and a predetermined threshold. Accordingly, the process of signal-detection can be speeded up, and the signals having a frequency identical to a working frequency can still be identified. As a result, the accuracy of a signal-reading process can be maintained over time.