LCD Array Substrate Gate Protrusions and Black Matrix
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Solution Overview
Problem
Liquid crystal display (LCD) devices face issues with gate electrode disconnection at crossing portions and low aperture ratio due to step differences in gate insulating layers and inadequate black matrix margins, leading to image quality deterioration and increased production costs.
Innovation Solution
The solution involves forming protrusions at the crossing portions of gate electrodes and semiconductor layers to prevent disconnection and incorporating a black matrix on the array substrate to enhance aperture ratio, which includes forming semiconductor layers, gate electrodes, and interlayer insulating layers with specific contact holes to ensure proper connection and alignment of electrodes, and using a black matrix that eliminates the need for additional margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate insulating layer is formed on a semiconductor layer with a step difference, then the gate electrode can be disconnected at crossing portions, but forming the gate insulating layer provides electrical insulation
Solution Approach 1:
The patent applies preliminary action by forming protrusions at the crossing portions of gate electrodes and semiconductor layers before forming the gate insulating layer. These protrusions are created in advance to prevent etchant pooling and subsequent gate electrode disconnection, eliminating the need for a gate insulating layer at crossing portions while maintaining electrical insulation where needed.
Solution Approach 2:
The patent extracts the gate insulating layer from the crossing portions of gate electrodes and semiconductor layers. By removing the gate insulating layer at these critical locations, the invention prevents etchant accumulation and gate electrode disconnection, while retaining the insulating layer in other areas where electrical insulation is required.
2Manufacturing precision
If the pixel electrode is spaced apart from gate and data lines to prevent cross-talk, then image quality improves, but the aperture ratio decreases
Solution Approach 1:
The patent introduces a black matrix as a sacrificial light-blocking structure that can be optimized independently. This black matrix serves as a disposable light management element that allows the pixel electrode to be positioned closer to gate and data lines without causing cross-talk, as the black matrix absorbs stray light and prevents interference.
Solution Approach 2:
The patent applies local quality by positioning the black matrix specifically at crossing portions and peripheral regions where light interference occurs. This localized light blocking allows the pixel electrode to extend closer to gate and data lines in non-crossing areas, thereby increasing the aperture ratio while maintaining image quality through targeted cross-talk prevention.
3Object-affected harmful factors
If the black matrix is formed with adequate margins to block light, then light leakage is prevented, but the aperture ratio is reduced due to additional margins
Solution Approach 1:
The patent applies partial action by forming the black matrix only at specific critical locations such as crossing portions and peripheral regions, rather than providing uniform margins across the entire display region. This selective light blocking prevents light leakage where it would cause harm while minimizing the area consumed by the black matrix, thereby preserving the aperture ratio.
4Ease of manufacture
If amorphous silicon is used in TFTs, then low temperature processing and cheap insulating substrates are enabled, but field effect mobility is low due to random silicon atom arrangement
Solution Approach 1:
The patent applies parameter changes by transitioning from amorphous silicon to polycrystalline silicon for TFT fabrication. This material parameter change increases field effect mobility due to the ordered crystal structure of polycrystalline silicon, while the process is designed to accommodate higher processing temperatures through adjusted fabrication parameters. The invention also integrates driving circuits on the same substrate, eliminating the need for expensive TAB processes and reducing overall manufacturing costs despite the material upgrade.
Data Source
AI summary
An array substrate for an LCD device includes a first TFT including a first semiconductor layer, a first gate electrode, wherein the first gate electrode is directly over the first semiconductor layer; a first protrusion extending from the first gate electrode along an edge of the first semiconductor layer; a second TFT including a second semiconductor layer, a second gate electrode, wherein the second gate electrode is directly over the second semiconductor layer; a second protrusion extending from the second gate electrode along an edge of the second semiconductor layer; a third TFT connected to crossed data and gate lines including a third semiconductor layer, a third gate electrode, wherein the third gate electrode is directly over the third semiconductor layer; a third protrusion extending from the third gate electrode along an edge of the third semiconductor layer; and a pixel electrode.