Self-Capacitive Touch Sensing Ghost Point Elimination
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Solution Overview
Problem
Self-capacitive touch panels often experience 'ghost points' where incorrect touch points are sensed, leading to inaccurate determination of touch coordinates.
Innovation Solution
A method involving sequential application of driving signals to row and column sensors to detect touch points, utilizing delay time periods of signals to differentiate between real and ghost points by considering touch points as dividers of resistors with different resistances, allowing precise determination of touch point coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional self-capacitive touch panels use row and column sensors to detect touch points, then multi-touch capability is achieved, but ghost points are generated leading to inaccurate touch coordinate determination
Solution Approach 1:
The patent applies preliminary action by first identifying candidate row and column sensors that may contain touch points before performing the actual touch coordinate determination. This preliminary identification step allows the system to narrow down the search space and apply more precise detection methods only where needed, thereby reducing ghost points while maintaining multi-touch capability.
Solution Approach 2:
The patent introduces an intermediary element - the delay time period measurement - to distinguish between real touch points and ghost points. By measuring the delay time of driving signals passing through candidate sensors, the system creates an additional detection dimension that helps differentiate true touches from false detections, thus improving touch coordinate accuracy.
2Productivity
If row and column sensors sense entire rows and columns simultaneously, then all touch points are detected, but ghost points are erroneously identified along with real touch points
Solution Approach 1:
The patent applies segmentation by dividing the sensor array into candidate row sensors and candidate column sensors based on initial detection results. Instead of processing all rows and columns uniformly, the system segments the detection process into stages: first identifying candidate sensors, then measuring delay times only for these candidates. This segmented approach maintains detection speed while improving accuracy.
Solution Approach 2:
The patent uses partial action by applying the detailed delay time measurement only to candidate sensors that are likely to contain touch points, rather than measuring all sensors. This partial application of the precise measurement method reduces computational overhead while still accurately identifying real touch points among the candidates.
3Measurement precision
If delay time period measurement is applied to all sensors, then accurate touch point determination is achieved, but system complexity and processing time increase
Solution Approach 1:
The patent reduces system complexity by performing preliminary identification of candidate sensors before applying the complex delay time measurement process. This preliminary filtering step significantly reduces the number of sensors that require detailed analysis, thereby lowering the overall computational complexity and processing time while maintaining high measurement precision for the final touch coordinate determination.
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 excludes ghost points and accurately determines the coordinates of real touch points, enhancing the precision of touch sensing in self-capacitive touch panels.
Implementation Method 1
The self-capacitive panels adopt ITO to produce vertical and horizontal electrode arrays on a surface of the glass. The vertical and horizontal electrodes respectively form capacitance, namely, the self-capacitive. When fingers touch the capacitive panels, the capacitance of the fingers may be overlapped on the capacitance of the panels, which increases the capacitance of the panels.
Implementation Method 2
considering touch points as dividers of resistors with different resistances
Data Source
AI summary
A positioning method for positioning two touch points of self-capacitive touch sensing devices is disclosed. The method includes: applying a first driving signals to the N rows of row sensors in sequence to determine the row sensors having the touch points; applying a second driving signals to the M columns of column sensors to determine the column sensor having touch points; applying a third driving signals to the row sensors or the column sensors; detecting a delay time period of the third driving signals within the row sensors or the column sensor so as to determine coordinates of the real touch points in accordance with the delay time period. In addition, a self-capacitive touch sensing device adopting the above method and a display device incorporating the above touch sensing device are also disclosed.