Touch Sensor Panel Disambiguation via Multi-Phase Scanning
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Solution Overview
Problem
Touch screens face performance degradation due to inability to distinguish between touch events from poorly grounded users or objects and those from floating objects like water drops, leading to false registrations and compromised user experience.
Innovation Solution
A touch sensor panel and controller system that uses multiple sets of driving signals to differentiate between touch events from well-grounded, poorly grounded, and floating objects by measuring current flow through sensing electrodes, employing self-capacitance and mutual capacitance principles to disambiguate touch inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch sensor panel uses standard capacitive sensing to detect touch events, then it can recognize user touches, but it cannot distinguish between touches from grounded users and floating objects like water drops
Solution Approach 1:
The patent segments the touch detection process into multiple phases by applying different driving signal configurations. First, a initial touch scan detects all capacitive changes. Then, a second scan with inverted or modified driving signals characterizes the electrical properties of detected objects. This segmentation allows the system to differentiate between grounded users (who show consistent capacitive coupling patterns across scans) and floating objects (which show inverted or anomalous patterns), thereby resolving the contradiction between detecting all touches and filtering false touches.
Solution Approach 2:
The patent changes the electrical parameters of the driving signals applied to sensing electrodes. By switching between different driving signal configurations (e.g., normal polarity, inverted polarity, different voltage levels), the system elicits different capacitive responses from grounded versus floating objects. Grounded users maintain consistent response characteristics across parameter changes, while floating objects exhibit inverted or erratic responses. This parameter variation enables accurate discrimination and reduces false touch registration.
2Reliability
If the touch sensor panel ignores all detected capacitive changes to avoid false touches from floating objects, then false registration decreases, but legitimate touches from poorly grounded users are also missed
Solution Approach 1:
The patent implements a feedback mechanism where the results of the first touch scan trigger a second characterization scan. When capacitive changes are detected, the system applies modified driving signals and measures the resulting current flow patterns. The feedback from this second scan determines whether to accept or reject the initial touch detection. Grounded user touches show consistent feedback patterns across scans and are accepted, while floating objects show inverted or inconsistent feedback and are rejected. This feedback loop maintains high valid touch recognition while filtering false touches.
Solution Approach 2:
The patent employs dynamic driving signal configurations that adapt based on detection needs. The system transitions from a standard detection mode to an inverted or modified signal mode when potential touches are detected. This dynamic switching allows the system to characterize unknown objects and determine their grounding status. By making the driving signals adaptive rather than static, the system can distinguish between poorly grounded users (who still show characteristic capacitive coupling) and floating objects (which show inverted responses), thereby maintaining high productivity while improving reliability.
3Measurement precision
If the touch sensor panel uses multiple scanning configurations to distinguish touch types, then discrimination accuracy improves, but processing time and complexity increase
Solution Approach 1:
The patent applies partial scanning by first performing a rapid initial touch scan to detect all capacitive changes. Only when touches are detected does the system perform the more time-consuming second characterization scan with modified driving signals. This partial application of the full scanning sequence reduces average processing time while maintaining discrimination accuracy, since most of the time the system only needs the quick first scan. The excessive action (second scan) is reserved only for cases where differentiation is actually needed.
Solution Approach 2:
The patent performs preliminary touch detection using standard driving signals before applying modified scanning configurations. This preliminary action quickly identifies potential touch locations and triggers the more complex discrimination process only where necessary. By preparing the system in advance with the initial scan and using its results to guide subsequent actions, the patent minimizes overall processing time while ensuring accurate discrimination when needed. The preliminary action filters out non-touch events, reducing the number of times the full multi-configuratio
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
Effectively differentiates between intended touch inputs from grounded users and unintended inputs from floating objects, enhancing touch screen performance by accurately recognizing user interactions while ignoring false inputs from water or other floating objects.
Implementation Method 1
measuring current flowing in and out of the one or more sensing electrodes during all of the time periods and determine if a touch event was created by a well grounded object or user a poorly grounded object or user, or if the object is floating
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
A touch input device configured to detect a touch input event and determine if the touch input event is caused by a floating object is provided. The touch input device includes one or more electrodes that scanned with a set of stimulation signals to first detect the presence of a touch event and then scanned with subsequent sets of stimulation signals in order to determine if the touch event is from a grounded object, a poorly grounded object, or a floating object.