Touch Sensor Compensation for Body Capacitance Grounding Effects
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Solution Overview
Problem
Touch sensitive devices often produce erroneous or distorted output values due to poor grounding of users or objects, especially when multiple touch events occur, as body capacitance affects the measurements.
Innovation Solution
The device operates in both stray capacitance mode to measure body capacitance and normal mode to detect touches, calculating a body capacitance factor to compensate for erroneous output values by switching between modes or operating them concurrently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the device operates in normal mode to detect touch events, then touch detection functionality is provided, but measurement accuracy deteriorates due to body capacitance effects from poor grounding
Solution Approach 1:
The system performs preliminary measurement of body capacitance effects before conducting normal touch detection. By measuring the body capacitance of the user's hand in advance (when not touching the screen), the system can compensate for grounding issues during subsequent touch events, thereby maintaining measurement accuracy despite poor grounding conditions.
Solution Approach 2:
The system uses feedback from body capacitance measurements to adjust and compensate touch detection readings. The measured body capacitance values are fed back into the system to calculate compensation factors that correct erroneous touch output values, improving the reliability of touch measurements under varying grounding conditions.
2Reliability
If repeated measurements are performed to improve accuracy, then measurement reliability improves, but response time increases
Solution Approach 1:
Body capacitance measurements are performed in advance during idle periods or between touch events, preparing compensation data before actual touch detection is needed. This preliminary preparation allows for faster real-time touch response without sacrificing accuracy, as the compensation factors are already calculated and ready for application.
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 provides more accurate and faster touch detection, reduces the need for repeated measurements, and adapts robustly to varying grounding conditions, improving the reliability and efficiency of touch sensitive devices.
Implementation Method 1
the touch sensitive device can recognize a touch event and the position of the touch event on the touch sensor panel
Implementation Method 2
various capacitances, such as the object's body capacitance between the object, e.g., a finger, and ground can distort the capacitances measured at the touch sensor panel
Data Source
AI summary
Measuring an effect of body capacitance in a touch sensitive device is disclosed. This effect can be caused by poor grounding of a user or other objects touching the device or of the device itself. The device can operate in a stray capacitance mode to measure a body capacitance effect and in a normal mode to detect a touch on the device. During the stray capacitance mode, the device can obtain a body capacitance measurement from the device. During the normal mode, the device can obtain a touch measurement from the device. The device can calculate a body capacitance factor based on a ratio between the body capacitance measurement and the touch measurement and use the body capacitance factor to compensate for erroneous or distorted touch output values from the device. Various components of the device can be switchably configured according to the particular mode.