Common Electrode Slits and Bridge Wiring for LCD Touch Panels
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Solution Overview
Problem
In liquid crystal display devices with in-cell touch panels, the narrow space between through holes makes it difficult to maintain reliable connections between common electrodes, leading to disconnections and increased electrical resistance.
Innovation Solution
The implementation of a common electrode with slits in the direction of scanning lines and bridge wirings over common metal wirings, connected by insulating films, ensures reliable electrical connections even in tight spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel size is decreased to achieve higher screen definition, then the screen resolution is improved, but the space between through holes becomes narrower making it difficult to maintain reliable connections between common electrodes
Solution Approach 1:
The common electrode is divided into multiple segments with slits between them. Each segment can be independently connected to common metal wirings, allowing flexible routing around through holes. This segmentation enables reliable connections even when space between through holes is narrow, as the slits provide alternative pathways for wiring connections.
Solution Approach 2:
The connection structure utilizes three-dimensional space by forming bridge wirings that extend over insulating films and connect common metal wirings from different locations. This vertical dimension allows connections to be made without requiring additional horizontal space between through holes, maintaining connection reliability in high-definition displays with narrow spacing.
2Manufacturing precision
If the space between through holes is narrowed due to smaller pixel size, then the screen definition is improved, but the workability of connecting common electrodes deteriorates
Solution Approach 1:
By segmenting the common electrode into multiple parts with slits, the wiring structure can be flexibly routed to connect each segment to common metal wirings. This segmentation simplifies the manufacturing process by allowing standard wiring techniques to be applied to each segment independently, maintaining ease of manufacture even with narrow spacing between through holes.
Solution Approach 2:
Insulating films are introduced as intermediary elements between bridge wirings and common metal wirings. These insulating films facilitate the connection process by providing a controlled interface that simplifies manufacturing while ensuring reliable electrical connections, making the overall process easier to manufacture despite narrow spacing constraints.
3Reliability
If bridge wirings are formed over common metal wirings with insulating films, then the connection reliability is improved, but the device structure becomes more complex
Solution Approach 1:
The insulating films serve multiple functions: they provide electrical insulation between bridge wirings and common metal wirings, they act as a substrate for forming bridge wirings, and they help planarize the surface for subsequent processing. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while maintaining improved connection reliability.
Data Source
AI summary
The purpose is to realize a high definition liquid crystal display device having touch panel function. The concrete structure is: The first substrate comprising; a plurality of scanning lines and a plurality of video signal lines, a semiconductor layer, a pixel electrode, a common electrode formed in plural pixels in common, a through hole to connect the semiconductor layer and the pixel electrode, a plurality of common metal wirings, which are formed on the common electrode and formed along the video signal lines; wherein the common electrode has a slit extending in the same direction as the scanning line extends, a bridge wiring is formed over the common metal wiring interposed by an insulating film at the place where the common metal wiring and the slit cross to each other, the common metal wiring and the bridge wiring are electrically connected to the common electrode near the edges of the slit.