Touch Substrate Isolation Layer Reduces Parasitic Capacitance
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Solution Overview
Problem
The increasing width of signal lines in touch screens leads to increased parasitic capacitance between the signal lines and the cathode layer of the display panel, resulting in decreased report rate and signal-to-noise ratio (SNR) due to ground capacitance.
Innovation Solution
A touch substrate with an isolation layer on its second surface, covering orthogonal projections of the signal lines, is used to reduce parasitic capacitance by isolating the signal lines from the cathode layer, and a method for preparing this substrate involves forming a touch area with alternating first and second electrodes, connecting them with signal lines, and forming through-holes to connect protection lines with the isolation layer, which is made of metal or transparent conductive material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of signal lines is increased to reduce impedance, then the impedance of signal lines is reduced, but the parasitic capacitance between signal lines and cathode layer increases
Solution Approach 1:
An isolation layer is introduced as an intermediary component between the signal lines and the cathode layer. This isolation layer acts as a mediator that reduces the harmful parasitic capacitance while allowing the signal lines to maintain their widened structure for lower impedance. The isolation layer is positioned at specific locations where it can effectively decouple the capacitive coupling between signal lines and cathode without interfering with the signal transmission function.
Solution Approach 2:
The isolation layer is segmented into specific regions rather than being a continuous structure. It is positioned to cover orthogonal projections of signal lines on the substrate, creating discrete isolation zones. This segmentation allows the isolation layer to reduce parasitic capacitance at critical locations while minimizing its impact on overall signal transmission and maintaining manufacturing feasibility.
2Reliability
If the width of signal lines is increased to reduce impedance, then the impedance of signal lines is reduced, but the ground capacitance increases and report rate decreases
Solution Approach 1:
The isolation layer serves as a mediator that reduces ground capacitance by electrically isolating the signal lines from the cathode layer. This mediation allows the signal lines to maintain wider widths for lower impedance while the isolation layer prevents excessive capacitive coupling that would otherwise increase ground capacitance and reduce report rate. The result is improved touch response speed without sacrificing impedance characteristics.
Data Source
AI summary
A touch substrate and a method for preparing the same, as well as a touch device are provided in embodiments of the disclosure, the touch substrate includes a substrate, the substrate having a touch area on a first surface thereof and a first peripheral area surrounding the touch area, the touch area including a plurality of first electrodes and a plurality of second electrodes arranged in a same layer and provided alternately to cross each other, and the first peripheral area including a plurality of first signal lines connected with the plurality of first electrodes, and a plurality of second signal lines connected with the plurality of second electrodes; and the touch substrate further includes an isolation layer provided on a second surface of the substrate, with an orthogonal projection of the isolation layer on the substrate covering orthogonal projections of the plurality of first signal lines and the plurality of second signal lines on the substrate, and the second substrate being opposite to the first substrate.