Dual-Layer Alignment Structure for LCD Baking and DC Charge Control
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Solution Overview
Problem
In liquid crystal display devices, the accumulation of residual DC charge in the insulating film leads to 'baking' or flicker, which is difficult to eliminate, and the use of two alignment layers can reduce baking but deteriorate display performance due to photoconductor current.
Innovation Solution
A liquid crystal display device with a first and second substrate sandwiching liquid crystal, featuring a first electrode and multiple second electrodes, an alignment layer with a first alignment layer of high resistance and high transmittance, and a second alignment layer of lower resistance and transmittance, formed using a polymerized PMDA compound, to reduce baking and photoconductor current impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the resistance of the first alignment layer is increased to prevent DC current generation, then baking is reduced, but residual DC charge accumulates in the insulating film and becomes difficult to eliminate
Solution Approach 1:
The alignment layer is divided into two separate layers: a first alignment layer with high resistance to prevent DC current and reduce baking, and a second alignment layer with low resistance to eliminate residual DC charge. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between preventing baking and eliminating residual DC.
Solution Approach 2:
Different regions of the alignment structure are assigned different electrical properties: the first alignment layer has high resistance characteristics to block DC current, while the second alignment layer has low resistance characteristics to conduct and eliminate residual DC charge. This local differentiation of properties enables simultaneous achievement of both objectives.
2Object-affected harmful factors
If a structure with two alignment layers is used to reduce baking, then residual DC can be eliminated, but display performance deteriorates due to photoconductor current generated by the first alignment layer absorbing light
Solution Approach 1:
The first alignment layer is designed with high resistance and high light transmittance properties, while the second alignment layer is designed with low resistance properties. This local differentiation ensures that the first layer does not generate significant photoconductor current (maintaining display performance) while the second layer effectively eliminates residual DC charge (reducing baking).
Solution Approach 2:
The alignment structure uses a composite of two different alignment layers with complementary properties. The first layer uses materials optimized for high resistance and high transmittance, while the second layer uses materials optimized for low resistance, creating a composite structure that achieves both reduced baking and maintained display performance.
3Manufacturing precision
If the transmittance of the second alignment layer is decreased to suppress photoconductor current, then display performance is improved, but the levelness of the liquid crystal side deteriorates
Solution Approach 1:
The first alignment layer is specifically designed with high light transmittance properties to maintain good levelness of the liquid crystal side, while the second alignment layer is designed with lower transmittance to suppress photoconductor current. This local differentiation of transmittance properties in different layers resolves the contradiction between maintaining levelness and suppressing photoconductor current.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces baking while maintaining display performance and preventing the deterioration of the liquid crystal side's levelness, suppressing photoconductor current and eliminating residual DC charge accumulation.
Implementation Method 1
there is a concern that the display performance is deteriorated due to current (photoconductor current) generated by the first alignment layer ORI1 absorbing light
Data Source
AI summary
The present invention provides a liquid crystal display device including a first substrate and a second substrate that are arranged to face each other while sandwiching liquid crystal, wherein: a first electrode and plural second electrodes are formed at a pixel area on the first substrate on the liquid crystal side; an alignment layer is provided which includes a first alignment layer formed on the first substrate on the liquid crystal side to cover the second electrodes and a second alignment layer formed on the first alignment layer on the liquid crystal side; the resistance of the second alignment layer is lower than that of the first alignment layer; and the transmittance of the second alignment layer is lower than that of the first alignment layer.