Touch Sensing Unit Ghost Signal Elimination
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Solution Overview
Problem
The electrostatic capacitance method for touch screen panels often experiences reduced accuracy due to ghost phenomena, where coupling between receiver pads and transmitter pads leads to incorrect recognition of touch positions, resulting in inaccurate touch position sensing.
Innovation Solution
A touch screen panel with a 1-layer mutual structure that includes a touch sensing unit capable of distinguishing actual touch signals from ghost signals by determining maximum values for every column, comparing these values, and identifying touch coordinates through the combination of transmitter and receiver pads corresponding to the greatest value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic capacitance method is used for touch sensing, then touch screen panel can achieve multi-touch recognition and higher durability, but ghost phenomenon occurs causing reduced touch position recognition accuracy
Solution Approach 1:
The patent divides the touch sensing area into multiple column groups, with each group containing a reference electrode and multiple sensing electrodes. This segmentation allows independent processing of capacitance changes in each column group, enabling the system to distinguish between actual touch signals and ghost signals by comparing capacitance changes across reference and sensing electrodes within each group.
Solution Approach 2:
The patent introduces reference electrodes as intermediary elements between the drive electrodes and sensing electrodes. These reference electrodes serve as mediators to compensate for parasitic capacitance and external electric field interference, allowing the system to isolate actual touch signals from ghost signals generated by coupling between adjacent electrodes.
2Adaptability or versatility
If mutual capacitance sensing is implemented, then multi-touch recognition capability is achieved, but coupling between receiver pads and transmitter pads generates ghost signals that reduce measurement precision
Solution Approach 1:
The patent segments the electrode array into multiple column groups where each group has a dedicated reference electrode. This segmentation enables the system to process capacitance changes locally within each group, preventing ghost signals from propagating across the entire sensor array and maintaining precise touch position recognition even during multi-touch events.
Solution Approach 2:
The patent implements a feedback mechanism where capacitance changes in reference electrodes are used to compensate for parasitic capacitance effects in sensing electrodes. By continuously monitoring and adjusting based on reference electrode signals, the system can distinguish between actual touch inputs and ghost signals caused by electrode coupling, thereby maintaining high measurement precision during multi-touch operations.
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 enhances the accuracy of touch position sensing by effectively differentiating actual touch signals from ghost signals, thereby improving the reliability of touch recognition in touch screen panels.
Implementation Method 1
a touch sensing unit configured to determine a touch position, based on changes in mutual capacitance between the receiver pads and the transmitter pads
Implementation Method 2
This utilizes a principle such that, when a pointer such as a person's finger is contacted with a surface of a touch screen panel, a position of the contact is recognized by detecting a change in the capacitance formed in a sensing cell (node) located on the contact surface, which is caused by the electric field of a human body
Data Source
AI summary
A touch screen panel and a driving method thereof. The touch screen panel includes a touch pad unit including a plurality of receiver pads and a plurality of transmitter pads combined with the receiver pads, and a touch sensing unit for determining a touch position, based on changes in mutual capacitance between the receiver pads and the transmitter pads. The touch sensing unit determines maximum values for every column by scanning touch sensing signals in the column direction of the touch pad unit, decides whether rows having maximum values for every column are the same, when the rows having the maximum values for every column are not the same, determines a greatest value by comparing all values of the scanned touch sensing signals, and determines touch coordinates through a combination of transmitter and receiver pads corresponding to the position at which the greatest value exists.