Doctor Roll and Blade Coating for LCD Alignment
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Solution Overview
Problem
Conventional roll printing devices face issues with uniform coating of alignment materials on larger substrates due to decreased pressure in the center portion and material non-uniformity caused by doctor roll abrasion, leading to uneven alignment layers in LCD manufacturing.
Innovation Solution
A roll printing device incorporating a combination of a doctor roll and a doctor blade to uniformly coat the alignment material on the anilox roll, addressing pressure and abrasion issues by ensuring consistent material distribution and minimizing spot generation on substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional roll printing device uses only a doctor roll to coat alignment material, then the coating process is simple, but the alignment material is not uniformly coated on the center portion of large substrates due to decreased pressure
Solution Approach 1:
The patent combines a doctor roll and a doctor blade into a single coating system. The doctor roll rotates in engagement with the anilox roll to apply pressure and uniform coating, while the doctor blade contacts the anilox roll to scrape off excess material. This merging of two different coating mechanisms (roller-based and blade-based) resolves the pressure deficiency in center portions while maintaining structural feasibility.
Solution Approach 2:
The coating function is segmented into two distinct components: the doctor roll handles the rotation and pressure application aspect, while the doctor blade handles the scraping and material removal aspect. This segmentation allows each component to optimize its specific function, with the doctor roll providing rotational motion and distributed pressure, and the doctor blade providing precise material control through contact scraping.
2Reliability
If a conventional roll printing device uses only a doctor roll, then the device structure is simple, but the doctor roll becomes abraded after repeated coating, causing spot generation on substrates
Solution Approach 1:
By merging the doctor roll and doctor blade, the system distributes the mechanical stress of coating between two components. The doctor blade, being a rigid scraping element, bears the brunt of material removal forces, protecting the doctor roll from excessive abrasion. This protects the rolling surface from degradation that would cause spotting.
Solution Approach 2:
The doctor blade acts as an intermediary between the anilox roll and the substrate. Instead of the doctor roll directly scraping material (which causes abrasion), the doctor blade performs the scraping function while the doctor roll provides rotational motion and pressure. This intermediary arrangement protects the rolling surface from direct contact abrasion.
3Productivity
If the size of substrate increases, then the production capacity increases, but the pressure between doctor roll and anilox roll decreases in the center portion, causing non-uniform coating
Solution Approach 1:
The combination of doctor roll rotation with doctor blade scraping creates a dual-mechanism coating system that maintains uniform material distribution across large substrate areas. The rotational motion provides consistent pressure distribution, while the blade ensures excess material is removed uniformly across the entire width, compensating for the reduced pressure in center portions of large substrates.
Solution Approach 2:
The doctor blade provides localized scraping action across different portions of the anilox roll surface. By adjusting the blade position and angle, the system can apply different levels of scraping force to different regions, compensating for the non-uniform pressure distribution that occurs with large substrate sizes and ensuring uniform coating quality across the entire substrate area.
Data Source
AI summary
A roll printing device, a roll printing method, and a method of fabricating an LCD device using the same are disclosed. The roll printing device includes a dispenser, an anilox roll receiving a predetermined material dispensed from the dispenser, a doctor roll rotating in engagement with the anilox roll to uniformly coat the predetermined material on the anilox roll, a doctor blade in contact with the anilox roll to uniformly coat the predetermined material on the anilox roll, and a printing roll supplied with the predetermined material from the anilox roll. The predetermined material is uniformly coated on the anilox roll by both the doctor roll and the doctor blade.