IPS Liquid Crystal Display Sealant UV Protection
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Solution Overview
Problem
Liquid crystal display panels face issues with moisture intrusion and mechanical reliability due to the deterioration of overcoat films during optical alignment and weak adhesion between organic and inorganic films, leading to peeling and reduced lifespan.
Innovation Solution
A liquid crystal display panel design where the sealant is bonded to the inorganic insulating film on the TFT substrate side and to the alignment film on the counter substrate side, preventing direct UV exposure to the overcoat film and ensuring strong bonding across both organic and inorganic film interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical alignment is performed by radiating polarized UV light to the alignment film, then liquid crystal molecules are aligned in a predetermined direction, but the overcoat film is deteriorated by UV exposure leading to moisture intrusion
Solution Approach 1:
The alignment film serves as an intermediary layer that absorbs UV light during optical alignment, protecting the overcoat film from direct UV exposure. This mediator prevents the harmful effect (UV deterioration) while maintaining the useful function (alignment precision).
Solution Approach 2:
The alignment film, which is normally just an alignment layer, is utilized to absorb UV radiation during the optical alignment process. This converts the potentially harmful UV exposure into a beneficial protective function, preventing deterioration of the overcoat film while achieving precise alignment.
2Manufacturing precision
If the alignment film is formed on the overcoat film for optical alignment, then liquid crystal molecules can be aligned, but adhesion between the alignment film and inorganic films becomes weak leading to peeling
Solution Approach 1:
The sealant is designed with different bonding characteristics for different regions: it bonds strongly to the inorganic insulating film at the TFT substrate side and to the alignment film at the counter substrate side. This local differentiation ensures both alignment precision and mechanical strength where needed.
Solution Approach 2:
The sealant structure combines bonding to both inorganic films and organic films (alignment film and overcoat film) in a composite configuration. This multi-interface bonding creates a reinforced seal that withstands vibrations and impacts while maintaining alignment functionality.
3Strength
If the sealant bonds to both inorganic and organic films, then mechanical strength is improved, but UV light exposure during optical alignment causes deterioration of organic materials
Solution Approach 1:
The alignment film acts as a UV-blocking intermediary layer that prevents UV light from reaching the overcoat film during optical alignment. This protects the organic materials from deterioration while allowing the sealant to bond to both inorganic and organic surfaces for mechanical strength.
Solution Approach 2:
The alignment film is formed in advance as a protective layer before the optical alignment process. This preliminary action ensures that when UV light is radiated during alignment, the overcoat film is already protected, preventing subsequent deterioration while enabling strong sealant bonding.
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
This configuration effectively prevents moisture intrusion and enhances mechanical reliability by maintaining the integrity of the overcoat film and ensuring strong adhesion, thereby extending the lifespan and withstanding vibrations and impacts.
Implementation Method 1
In optical alignment method, a polarized UV light is radiated to an alignment film, and thereby, such anisotropy that liquid crystal molecules are aligned in a predetermined direction, is provided to the alignment film
Implementation Method 2
the sealant is bonded to the inorganic insulating film at the seal portion on the side where the TFT substrate is formed, with the first alignment film being not provided on the side, and wherein, in the seal portion on the side where the counter substrate is formed, the sealant is bonded to the second alignment film
Data Source
AI summary
An IPS system liquid crystal display device is provided to prevent reliability for a seal portion from lowering, which is caused by the fact that an overcoat film at a portion where an alignment film is not present is deteriorated by ultraviolet light during optical alignment process. An alignment film 113 subjected to optical alignment is formed above each surface of a TFT substrate 100 and of a counter substrate 200, the alignment film 113 on the side of the TFT substrate 100 is not formed in the seal portion, and a sealant 150 is bonded to an inorganic insulating film 109. On the side of the counter substrate 200, the alignment film 113 is formed on an overcoat film 203 and the sealant 150 is bonded to the alignment film 113. Since the ultraviolet light is not radiated directly to the overcoat film 203 when optical alignment is performed on the alignment film 113, the overcoat film 203 can be prevented from deterioration and, accordingly, intrusion of moisture from the deteriorated portion of the overcoat film can be prevented.