Array Substrate Touch Signal Routing for Pixel Edge Light Leakage
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Solution Overview
Problem
The layout of touch signal and source signal fan out lines in existing touch display driver integration (TDDI) products leads to overlapping metal layers, causing alignment issues and resulting in abnormal liquid crystal orientation and poor light leakage at pixel edges.
Innovation Solution
The array substrate design includes staggered upper and lower touch signal lines, with the upper line positioned perpendicular to the lower line, and a staggered arrangement of via holes to ensure proper alignment and reduce overlapping capacitance, maintaining the normal orientation of liquid crystal and preventing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch signal fan out lines are arranged on both sides of source signal pad, then touch signal routing is achieved, but metal layer overlap occurs causing alignment issues
Solution Approach 1:
The patent introduces a third metal layer (TPM layer) specifically for touch signal routing, separating touch signal lines from source signal lines in the vertical dimension. This dimensional separation eliminates the overlap problem between touch and source signal fan out lines, allowing both to be routed without causing alignment issues in existing metal layers.
2Device complexity
If same metal layer is used for source and touch signal wiring, then device complexity is reduced, but liquid crystal orientation becomes abnormal
Solution Approach 1:
The patent segments the metal layers into distinct functional layers: source signal lines use existing metal layers (GATE/SD layers), while touch signal lines use a dedicated TPM layer. This segmentation allows each signal type to be routed independently without interfering with liquid crystal orientation, resolving the conflict between device complexity and crystal alignment stability.
3Productivity
If touch signal lines are positioned close to data lines, then pixel opening rate is improved, but light leakage occurs at pixel edges
Solution Approach 1:
The patent introduces a black matrix as an intermediary barrier between the touch signal lines and data lines. This black matrix absorbs stray light and prevents light leakage from reaching the pixel edges, allowing touch signal lines to be positioned close to data lines for high pixel opening rate while eliminating the harmful light leakage effect.
Data Source
AI summary
This disclosure provides an array substrate and a preparation method thereof as well as a touch display device. The array substrate includes a substrate, a plurality of gate lines and a plurality of data lines on the substrate. The plurality of gate lines extend along a first direction and are arranged in a second direction different from the first direction, the plurality of data lines extend in the second direction and are arranged in the first direction, the plurality of gate lines intersect with the plurality of data lines to define a plurality of pixel areas. A plurality of touch signal lines are on the substrate and includes a lower touch signal line and an upper touch signal line, and an edge of the upper touch signal line is spaced apart from an edge of the lower touch signal line in the first direction.