In-Cell Touch Display Reducing Mask Counts via Merged Contact Holes
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Solution Overview
Problem
The manufacturing process for in-cell type touch panels integrated with liquid crystal display devices is complicated due to the need for separate steps to form contact holes for connecting signal lines and common/touch electrodes, and existing technologies do not provide a configuration for connecting signal lines formed in the same layer as pixel electrodes with touch sensors, leading to increased mask counts and photolithography steps.
Innovation Solution
A display device configuration and manufacturing method that includes a first organic insulating layer covering video signal lines, a first metal layer extending along these lines, and multiple conductive layers connected via specific contact holes to simplify the integration of touch sensors with liquid crystal display devices, reducing the number of masks and photolithography steps required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate steps are used to form contact holes for connecting signal lines and common/touch electrodes, then connection reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the formation of contact holes for signal lines and common/touch electrodes into a single photolithography step. The conductive layer is patterned to include both signal line contact holes and common electrode contact holes simultaneously, eliminating the need for separate manufacturing steps while maintaining reliable electrical connections.
Solution Approach 2:
The conductive layer serves multiple functions: it acts as both the pixel electrode and the common electrode, and the same photolithography process forms contact holes for both signal lines and common electrodes. This multi-functionality reduces the number of manufacturing steps while ensuring consistent connection quality.
2Manufacturing precision
If multiple photolithography steps are used to form different conductive layers and contact holes, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent merges multiple photolithography steps into a single step by designing the conductive layer pattern to include all necessary contact holes (signal line contacts and common electrode contacts) in one exposure and development process. This reduces manufacturing cycle time while maintaining pattern precision through careful photomask design.
Solution Approach 2:
The conductive layer is designed and patterned in advance to incorporate all future contact points for both signal lines and common electrodes. This preliminary configuration eliminates the need for subsequent alignment steps, improving productivity without sacrificing precision.
3Reliability
If the conductive layer is extended along video signal lines, then electrical connection is improved, but device complexity increases
Solution Approach 1:
The conductive layer performs dual functions: it serves as the pixel electrode for liquid crystal control and as the common electrode for touch sensor operation. By extending this single layer along the video signal lines, the patent achieves reliable electrical connections for both display and touch functions without adding separate conductive structures.
Solution Approach 2:
The patent combines the pixel electrode and common electrode into a single conductive layer that extends along the video signal lines. This merging approach ensures reliable electrical connections for both display and touch functions while simplifying the overall device structure compared to using separate conductive layers.
Data Source
AI summary
A display device includes a first organic insulating layer covering video signal lines; a first metal layer provided above the first organic insulating layer; a first conductive layer provided above the first organic insulating layer and connected to a switching element via a first contact hole; a first inorganic insulating layer covering the first conductive layer and the first metal layer; a second conductive layer provided above the first inorganic insulating layer and connected to the first metal layer; a second inorganic insulating layer provided above the second conductive layer; a third conductive layer provided above the second inorganic insulating layer and connected to the first conductive layer via a second contact hole; and a fourth conductive layer provided above the second inorganic insulating layer, connected to the first metal layers via a third contact hole, and connected to the second conductive layer via a fourth contact hole.