Touch Sensing Baseline Update for Continuous Movement Detection
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Solution Overview
Problem
Touch sensing systems, particularly of the capacitance type, fail to recognize user input when fingers move between regions without detaching, due to small changes in sensing signals not being adequately detected.
Innovation Solution
A touch sensing system with a baseline updating unit that calculates and compares difference values between sensing signals and baselines, using a comparator and arithmetic unit to update baselines and filter coefficients, ensuring continuous touch recognition by adjusting baselines and output signals based on predetermined equations and coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the baseline updating unit updates baselines to keep up with sensing signal changes caused by noise, then noise influence is minimized, but touch movement after initial contact is not recognized
Solution Approach 1:
The patent applies local quality by differentiating baseline updating behavior between different spatial regions. When a touch is detected in a specific region, the baseline updating is selectively inhibited only in that region and its adjacent regions, while allowing continued updating in other regions. This localized control enables the system to maintain noise adaptation capability in untouched areas while preserving touch movement detection capability in contacted areas.
Solution Approach 2:
The patent implements dynamics by making the baseline updating process adaptive and state-dependent. The baseline updating unit dynamically adjusts its behavior based on the detected touch state: it updates baselines during normal operation to track noise, but suspends updating when touch is detected to maintain sensitivity to touch movement. This dynamic switching resolves the contradiction between noise compensation and touch movement detection.
2Reliability
If the system uses fixed reference values for touch detection, then noise influence is reduced, but small changes in sensing signals during touch movement are not detected
Solution Approach 1:
The patent makes the reference baseline dynamic rather than fixed. The baseline is continuously updated during normal operation to track noise variations, providing stability. When touch is detected, the baseline updating is temporarily suspended, maintaining a stable reference that is sensitive to touch movement. This dynamic reference mechanism resolves the contradiction between stability and sensitivity.
Solution Approach 2:
The system uses feedback from the touch detection process to control baseline updating. When touch is detected (sensing signal exceeds reference value), this feedback triggers baseline updating suspension. When no touch is present, baseline updating continues. This feedback loop enables the system to automatically adjust its reference behavior based on operational conditions, resolving the contradiction between fixed stability and dynamic sensitivity.
3Object-affected harmful factors
If baselines are updated continuously to track noise, then noise compensation is improved, but touch movement recognition is lost
Solution Approach 1:
The patent applies local quality by implementing region-specific baseline updating control. When touch is detected in a particular region, baseline updating is inhibited only in that region and its adjacent regions, while continuing in other regions. This selective approach allows noise compensation in untouched areas while maintaining touch movement detection capability in contacted areas.
Solution Approach 2:
The patent prepares for touch movement detection by preemptively inhibiting baseline updating when touch is first detected. This preliminary action prevents the baseline from adapting to touch-induced signal changes before they occur, ensuring that subsequent touch movements are detected as deviations from the pre-touch baseline rather than being absorbed by continuous updating.
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
Enhances touch sensitivity by accurately detecting user input even during movement across regions, preventing missed touches and improving overall system responsiveness.
Implementation Method 1
the touch screen of the capacitance type detects touch positions by detecting change in the capacitance produced when a person's hands or objects contact the touch screen
Data Source
AI summary
A touch sensing system comprises: a touch sensing unit which includes regions having predetermined coordinates; and a baseline updating unit for updating a baseline by reflecting sensing signals outputted from the touch sensing unit. The baseline updating unit includes a comparator for calculating difference values between the sensing signal of an n-th frame and the baseline of an n−1-th frame for each region, and for comparing the difference values with predetermined reference values. The touch sensing system further comprises an arithmetic unit for setting the baseline of the n−1-th frame as the baseline of the n-th frame for a region in which the difference values are larger than the reference values and for the region adjacent to it, and for updating the baseline of the n-th frame by a predetermined arithmetic for a remaining region.