Liquid Crystal Display Passivation Layer Thickness Control
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Solution Overview
Problem
Liquid crystal displays experience surface and line afterimages due to differences in optimum common voltages between white and black images, leading to poor side visibility.
Innovation Solution
The thickness of the passivation layer in the lower portion of the black matrix and the pixel electrode is controlled to reduce surface and line afterimages, with the additional insulating layer thickness ranging from 1,000 to 3,000 Å, and the interlayer insulating layer thickness varying accordingly to expose specific electrodes and layers, thereby offsetting voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different common voltages are applied for white and black images to improve side visibility, then side visibility is improved, but surface afterimage is generated due to voltage difference
Solution Approach 1:
The patent applies different passivation layer thicknesses in different regions: a first passivation layer with thickness of 500-1500 Å in the data line region and a second passivation layer with thickness of 1500-3000 Å in the black matrix region. This local differentiation allows voltage compensation in the black matrix region while maintaining normal operation in the data line region, thereby reducing surface afterimage while preserving side visibility.
2Object-generated harmful factors
If passivation layer thickness is increased to compensate voltage difference, then surface afterimage is reduced, but manufacturing complexity increases
Solution Approach 1:
The passivation layer is segmented into two distinct regions with different thicknesses: the first passivation layer over the data line and the second passivation layer over the black matrix. This segmentation allows each region to have optimized thickness for its specific function, reducing surface afterimage through the thicker layer while avoiding unnecessary complexity by maintaining a relatively simple overall structure.
Data Source
AI summary
A liquid crystal display includes: a first substrate; a gate line on the first substrate; a gate insulating layer on the gate line; a semiconductor layer on the gate insulating layer; a data line and a drain electrode on the semiconductor layer; a passivation layer covering the data line and the drain electrode; a common electrode on the passivation layer; an interlayer insulating layer on the common electrode; a pixel electrode on the interlayer insulating layer; an additional insulating layer on the pixel electrode; a second substrate opposite to the first substrate; and a black matrix on the second substrate, and including a vertical portion covering the data line and a horizontal portion covering the gate line and the drain electrode, where an empty portion is defined through the additional insulating layer in a portion corresponding to the black matrix.