Inkjet Alignment Layer Printing for Large Substrates
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Solution Overview
Problem
Conventional alignment layer printing apparatuses face difficulties in manufacturing larger panels due to the increasing size and weight of rolls and rubber plates, making it challenging to form uniform alignment layers efficiently.
Innovation Solution
An inkjet alignment liquid printing apparatus with rotating and elevatable printing stages and inkjet heads that deposit alignment liquid in a grid pattern, eliminating the need for rolls and rubber plates, and allowing for precise control of drop placement and voltage pulses to optimize layer planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flexo printing with rolls and rubber plates is used to form alignment layers, then alignment layers can be formed on substrates, but the size and weight of the rolls and plates increase as substrate size increases, making manufacturing difficult
Solution Approach 1:
The patent replaces the mechanical flexo printing system (rolls and rubber plates) with an inkjet printing system. The inkjet printing apparatus uses ejection nozzles to deposit alignment liquid directly onto the substrate, eliminating the need for large rolls and plates. This substitution of mechanical system with a different printing mechanism resolves the contradiction by maintaining alignment layer formation capability while significantly reducing apparatus size and weight.
Solution Approach 2:
The patent changes the fundamental parameter of the printing method from contact-based mechanical printing to non-contact inkjet ejection. By controlling parameters such as ejection frequency, liquid viscosity, and substrate movement speed, the system achieves uniform alignment layer formation without requiring large mechanical components. This parameter optimization allows for compact apparatus design while maintaining manufacturing precision.
2Area of stationary object
If the size of panels and mother substrates become larger, then more display area is available, but the size and weight of rolls and plates increase, making alignment layer printing difficult
Solution Approach 1:
The inkjet printing system replaces the mechanical roll-and-plate system that becomes unwieldy with large substrates. The inkjet apparatus can accommodate substrates of various sizes by moving the substrate through a controlled ejection zone, eliminating the need for proportionally larger rolls and plates. This resolves the contradiction by enabling printing on large areas without increasing apparatus size.
Solution Approach 2:
The patent employs dynamic substrate movement through the inkjet ejection zone, allowing the apparatus to handle large substrates by moving them rather than requiring the printing mechanism to span the entire substrate area. This dynamic approach enables easy manufacturing on large substrates by decoupling the apparatus size from the substrate size.
3Productivity
If conventional inkjet printing is used without rotation, then printing can be performed, but uniform alignment layers are difficult to achieve on larger substrates
Solution Approach 1:
The patent introduces substrate rotation during the inkjet printing process to achieve uniform alignment layer formation. By rotating the substrate while ejecting alignment liquid, the system ensures even distribution of the liquid across the substrate surface. This dynamic rotation mechanism resolves the contradiction by maintaining high printing speed while achieving uniform alignment layer precision on large substrates.
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 solution enables the formation of uniform alignment layers with reduced planarization time and manufacturing complexity, accommodating larger substrates without the weight and size issues of traditional equipment, and allows for varied printing patterns.
Implementation Method 1
a plurality of inkjet heads injecting an alignment liquid onto a substrate
Implementation Method 2
a portion of the printing stage is elevated and rotated
Data Source
AI summary
An inkjet method of printing an alignment layer is presented. The method entails depositing drops of an alignment liquid on a substrate while moving a plurality of inkjet heads and/or the substrate relative to each other to form a first dropping line on the substrate. The method also entails rotating a printing stage on which the substrate is mounted, and depositing drops of the alignment liquid on the substrate after forming the fist dropping line to form a second dropping line. Since the printing stage is elevated and rotated, the drops of the alignment liquid are easily deposited in a grid pattern to decrease the space between adjacent drops. If desired, drops may be skipped to avoid depositing the alignment liquid multiple times on the same location on the substrate. With this method, the planarization time of the alignment layers is shortened.