Touch Panel Electrode Structure for Low-Noise Display Sensing
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Solution Overview
Problem
Existing electrostatic capacitive touch panels suffer from increased line capacitance due to intersecting signal lines, leading to reduced signal-to-noise ratio (S/N ratio) and detection sensitivity, particularly when used with display devices, which can result in erroneous operation and decreased performance.
Innovation Solution
The design minimizes line capacitance by orthogonal intersection of signal lines on a flexible printed circuit board, equalizes electrode capacitance between X and Y directions, and incorporates a transparent conductive film to shield noise from the display panel, while supplying signals to electrodes from both ends to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal lines are arranged to supply signals to X and Y electrodes, then signal transmission is enabled, but line capacitance increases due to intersecting lines
Solution Approach 1:
The signal lines are segmented into separate groups for X electrodes and Y electrodes, with each group routed through different regions of the flexible printed circuit board. This segmentation prevents the lines from intersecting, thereby reducing line capacitance while maintaining signal transmission capability to all electrodes.
Solution Approach 2:
The patent utilizes the three-dimensional space of the flexible printed circuit board by routing X electrode signal lines and Y electrode signal lines in different spatial planes or layers. This dimensional separation allows both sets of lines to coexist without intersection, minimizing line capacitance effects.
2Measurement precision
If electrode area is increased to improve signal level, then detection sensitivity improves, but capacitance to ground increases causing more noise
Solution Approach 1:
The patent applies different properties to different regions of the electrodes. The electrode areas are optimized to provide sufficient signal level for detection, while local shielding structures are added in regions where noise from the display device is most problematic. This localized approach allows the electrodes to maintain high detection sensitivity without uniformly increasing capacitance to ground across the entire electrode area.
Solution Approach 2:
A transparent conductive film is introduced as an intermediary layer between the electrodes and the display device. This film acts as a shield that blocks noise from the display device from coupling into the electrodes, allowing the electrodes to maintain larger area for signal detection without proportionally increasing noise susceptibility.
3Object-affected harmful factors
If transparent conductive film is added to shield noise, then noise reduction is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent uses a transparent conductive film that has uniform properties across the touch panel surface. This homogeneous material can be applied using standard thin-film deposition techniques already employed in touch panel manufacturing, such as sputtering or chemical vapor deposition. By using a uniform material and process that integrates with existing manufacturing steps, the patent achieves noise shielding without significantly increasing manufacturing complexity.
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 results in a highly reliable electrostatic capacitive touch panel with improved detection sensitivity and reduced noise interference, ensuring accurate finger touch input detection.
Implementation Method 1
incorporates a transparent conductive film to shield noise from the display panel
Implementation Method 2
the capacitance of electrodes on one line in a state that the one-line electrode line is not touched by a finger or the like (in a steady state) is formed of inter-electrode capacitance
Data Source
AI summary
A display device includes a display panel, and an electrostatic capacitive type touch panel which is formed in an overlapping manner with the display panel. A plurality of X electrodes and a plurality of Y electrodes intersecting with the X electrodes. A first signal line supplies signals to the X electrodes, a second signal line supplies signals to the Y electrodes, and the first signal line and the second signal line are formed on a flexible printed circuit board. A dummy electrode is formed adjacent to an electrode portion of each X electrode and electrode portion of each Y electrode, the dummy electrode does not overlap the X electrode and the Y electrode, and the dummy electrode does not electrically connect with the first and second signal lines.