Zigzag Matrix Touch Panel Electrodes for Moire Reduction
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Solution Overview
Problem
Conventional matrix switching type touch panels face issues where transparent electrodes become visually distinguishable due to patterning marks, and the Moire effect occurs due to the alignment of signal lines and pixel electrodes, leading to poor screen quality and increased visibility of boundaries between electrode areas.
Innovation Solution
The touch panel design features unit electrodes arranged in a zigzag format with alternating slanted sections, bridges connecting these electrodes, and signal lines formed by multiple unit signal lines to reduce resistance and visibility, while the bridges and protrusions are made of the same transparent electroconductive material to minimize visibility and prevent the Moire effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If transparent electrodes are patterned to form touch pads and signal lines, then the touch panel structure is defined, but the boundaries between areas with and without transparent electrodes become visually distinguishable
Solution Approach 1:
The transparent electrode is divided into multiple unit electrodes arranged in a matrix pattern. Each unit electrode is separated by spacing, creating a dotted rather than continuous pattern. This segmentation reduces the visual impact of boundaries while maintaining electrical functionality through the distributed array of electrode units.
Solution Approach 2:
The transparent electrode material is applied with varying local properties - the unit electrodes have different transparency and spacing characteristics compared to the surrounding areas. By controlling the local distribution and optical properties of the transparent electrode material, the visual uniformity is improved while maintaining functional areas.
2Length of stationary object
If signal lines are made longer to connect touch pads and touch driving circuit, then the connection is achieved, but resistance and parasitic capacitance increase
Solution Approach 1:
The signal lines are routed to extend into the invisible area below the visible display region. By utilizing the third dimension (depth/layers) and extending conductors into non-visible regions, the signal transmission path is lengthened without compromising visual appearance, while the increased wire length in invisible areas does not affect screen quality.
Solution Approach 2:
A bridge electrode serves as an intermediary component connecting the unit electrodes in the visible area to the signal lines extending into the invisible area. This bridge structure facilitates electrical connection while transitioning between different functional zones, allowing signal transmission without direct exposure in the visible region.
3Reliability
If signal lines are made wider to compensate for longer wire length, then resistance is reduced, but the boundaries between signal lines become densely disposed and more visible
Solution Approach 1:
Signal lines are routed into the invisible area where they can have sufficient width for low resistance without contributing to visual artifacts. By moving conductors from the visible to invisible region, the design achieves both electrical performance and visual quality.
Solution Approach 2:
The signal transmission function is distributed across multiple unit signal lines rather than relying on a single wide conductor. This segmentation allows each individual line to be narrower and less visible, while collectively they provide sufficient current carrying capacity and signal integrity.
4Ease of manufacture
If unit electrodes are arranged in straight lines parallel to signal lines, then manufacturing is simplified, but the Moire effect occurs due to overlapping patterns
Solution Approach 1:
The unit electrodes are arranged in a zigzag pattern rather than straight parallel lines, creating an asymmetric configuration relative to the signal lines. This asymmetric arrangement disrupts the periodic overlap that causes Moire effects, while the zigzag pattern maintains manufacturability through standard photolithography processes.
Solution Approach 2:
The straight linear arrangement of electrodes is replaced with a curved zigzag pattern. This curvature introduces variation in the spatial frequency and orientation of electrode features, preventing the regular interference patterns that produce Moire effects while remaining compatible with conventional manufacturing methods.
Data Source
AI summary
Provided is a matrix switching type touch panel including a plurality of touch pads disposed in a visible area on a substrate in a dot matrix format, the touch pads spaced from one another, and a plurality of signal lines disposed in a space between the touch pads, each connecting a touch pad and a touch driving circuit of an invisible area. The panel comprises: unit electrodes made of a transparent electroconductive material and disposed within the visible area; touch pad areas each determined in an area corresponding to each touch pad; signal line areas each determined in an area corresponding to each signal line; and bridges electrically connecting the plurality of unit electrodes disposed in each touch pad area and each signal line area. The unit electrodes are arranged in a zigzag format with respect to a first axis parallel to the signal lines.