Multi-Via Touchscreen Electrode Shielding
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Solution Overview
Problem
Capacitive touch screens face challenges in mitigating unwanted capacitive coupling, which can lead to noise interference and reduced sensitivity due to the integration of touch sensing circuitry with display pixels, affecting the accuracy and reliability of touch detection.
Innovation Solution
A touch screen design incorporating multiple electrode layers electrically coupled using vias, with a top shielding layer, a touch sensing layer, and a bottom shielding layer, driven with electrical signals to mitigate capacitive coupling, and featuring opaque masks and passivation layers to reduce visibility and corrosion, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If touch sensing circuitry is integrated with display pixels, then device complexity is reduced and manufacturing is simplified, but capacitive coupling noise increases and touch detection accuracy deteriorates
Solution Approach 1:
The touch screen is divided into multiple electrode layers (first electrode layer, second electrode layer, third electrode layer) with distinct functions. The first and third layers serve as shielding electrodes while the second layer serves as the touch sensing electrode, physically separating sensing functions from shielding functions to reduce capacitive coupling noise.
Solution Approach 2:
Via structures are introduced as intermediary conductive elements to electrically connect the first, second, and third electrode layers. These vias enable the shielding electrodes to be effectively coupled to the touch sensing electrode, allowing noise mitigation while maintaining touch detection accuracy.
2Reliability
If shielding electrodes are added to mitigate capacitive coupling, then touch detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the electrode layers: the first electrode layer serves as both a structural component and a shielding electrode, the second layer serves as both a structural component and a touch sensing electrode, and the third layer serves as both a structural component and a shielding electrode. This merging approach reduces the need for additional separate shielding structures.
Solution Approach 2:
The patent transitions from a single-plane electrode structure to a multi-layer stacked structure with vias providing vertical electrical connections. This three-dimensional arrangement allows shielding electrodes to be positioned above and below the touch sensing electrode, effectively mitigating capacitive coupling from both directions without requiring lateral expansion.
3Reliability
If multiple electrode layers are electrically coupled using vias, then capacitive coupling noise is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The via structures are designed with predetermined positions and dimensions during the planning stage. The first, second, and third electrode layers are configured with via holes at specific locations that align with the vias, allowing for pre-planned electrical connections that reduce alignment complexity during manufacturing.
Solution Approach 2:
The patent applies different via configurations at different locations: some vias connect only the first and second electrode layers, while other vias connect all three electrode layers. This localized differentiation allows optimization of electrical connections in specific regions without requiring uniform high-precision connections across the entire structure.
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 design effectively reduces capacitive coupling noise, enhances sensitivity, and improves the accuracy of touch detection by ensuring all electrode layers are at the same electric potential, thereby enhancing the overall performance of the touch screen.
Implementation Method 1
The first electrode layer, the second electrode layer, and the third electrode layer can be electrically coupled together using a plurality of via structures
Implementation Method 2
the first electrode layer, the second electrode layer, and the third electrode layer can be driven with the same electric potential to mitigate unwanted capacitive coupling
Data Source
AI summary
The disclosure relates to a touch screen including a first electrode layer, a second electrode layer, and a third electrode layer. The touch screen can include shield-sensor vias connecting the first electrode layer and the second electrode layer and shield-shield vias connecting the first electrode layer and the third electrode layer, for example. The shield-sensor vias can be placed in a bond pad region of the touch screen, which can further include connections between one or more routing traces connected to one or more touch electrodes and touch or other circuitry further included in the electronic device. The shield-shield vias can be placed in an outer region located around an inner region of the touch screen. In some examples, one or more routing traces can include diverted portions to maintain a threshold distance between the routing traces and the one or more shield-shield vias.