Projected Capacitive Touch Panel Conducting Material Interference Prevention
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Solution Overview
Problem
Projected capacitive touch panels face interference and misjudgment issues due to conducting materials, such as water, which affect the detection of touch points by altering stray capacitance and current changes among axial conductive lines.
Innovation Solution
The solution involves providing a first sensing signal to isolated axial conductive lines, sensing simultaneous second and third signals, and utilizing changes in these signals to accurately determine touch point coordinates, ensuring that conducting materials do not interfere with the detection process by maintaining equal voltage levels among the conductive lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional point detection method is used in projected capacitive touch panel, then touch point can be detected through stray capacitance changes, but conducting materials cause misjudgment and detection errors
Solution Approach 1:
The patent applies equipotentiality by providing the same sensing signal to all axial conductive lines simultaneously, making them处于同一电位状态. This eliminates potential differences that would otherwise cause current flow through conducting materials on the touch panel surface, thereby preventing misjudgment and maintaining accurate touch point detection despite the presence of conducting materials.
Solution Approach 2:
The patent extracts and eliminates the harmful effect of conducting materials by using a uniform sensing signal approach. By making all axial conductive lines equipotential, the method effectively removes the interference mechanism (current flow through conducting materials) from the detection system, allowing accurate touch point identification even when conducting materials are present on the surface.
2Measurement precision
If sensing signal is provided to axial conductive lines, then touch point position can be determined through current changes, but conducting materials alter stray capacitance and cause detection errors
Solution Approach 1:
The patent ensures all axial conductive lines are at the same potential by providing the identical sensing signal to each line. This equipotential condition prevents current flow through any conducting materials present on the touch panel, eliminating the reliability issue of detection errors while maintaining the ability to accurately determine touch point position through capacitance changes.
3Difficulty of detecting and measuring
If different sensing signals are provided to different axial conductive lines, then individual line detection is possible, but potential differences cause current flow through conducting materials leading to misjudgment
Solution Approach 1:
The patent resolves the contradiction by providing the same sensing signal to all axial conductive lines, making them equipotential. This approach maintains individual line detection capability while eliminating potential differences that would cause current flow through conducting materials, thereby preventing misjudgment and improving overall detection accuracy.
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 method effectively prevents the influence of conducting materials on touch point detection, allowing for precise identification of touch points without interference, even in the presence of conducting areas like water, thereby enhancing the accuracy and reliability of touch panel operations.
Implementation Method 1
when a user uses his/her finger or conducting material to approach or touch a touch point TP on the projected capacitive touch panel 100, the finger or the conducting material on the touch point TP forms an extra capacitance with the first and the second axial conductive lines 124, 144. This causes the value of the equivalent capacitance to be changed.
Implementation Method 2
The first sensing layer 120 has a plurality of first patterned electrodes 122 serially connected by a plurality of first axial conductive lines 124 correspondingly, and then electrically connected to a plurality of first outside-connection conducting wires 126 correspondingly.
Data Source
AI summary
This invention provides a device for preventing the influence of conducting material from point detection of projected capacitive touch panel. The device includes a first sensing layer having a plurality of first axial conductive lines isolated from each other and electrically connected to a plurality of first outside-connection conducting wires correspondingly, a second sensing layer having a plurality of second axial conductive lines isolated from each other and electrically connected to a plurality of second outside-connection conducting wires correspondingly, a signal driving line electrically connecting to the first and the second outside-connection conducting wires to provide a first sensing signal, and a sensing unit electrically connecting the first and the second outside-connection conducting wires to sense the sensing signal on the first and the second axial conductive lines. Wherein, the second sensing layer is on a dielectric layer, the first sensing layer, and a substrate in sequence.