Vacuum-less Roll-filling for Flexible Electro-optic Cells
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Solution Overview
Problem
Current methods for manufacturing large flexible liquid crystal devices are inefficient due to difficulties in maintaining uniform cell gap and preventing air penetration, leading to non-uniform optical and electrical properties, and existing technologies are not compatible with plastic substrates, limiting their use in applications requiring flexibility and durability.
Innovation Solution
A vacuum-less roll-filling method using flexible substrates with unpatterned spacers and a border sealant to maintain a controlled distance between substrates, allowing for the electro-optic material to fill the gap without vacuum conditions, enabling continuous production and improved optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vacuum filling process is used for large area panels, then liquid crystal can be introduced into the panel gap, but the filling time becomes excessively long and process efficiency decreases
Solution Approach 1:
The gasket is pre-formed with a through-hole structure that allows liquid crystal to be introduced from the edge of the panel. The alignment layers are pre-coated on substrates before assembly. This preliminary preparation enables faster filling by eliminating the need for vacuum evacuation of large panel areas, as liquid crystal can flow directly into the gap through capillary action via the pre-positioned through-hole.
Solution Approach 2:
The invention extracts the filling hole from the traditional vacuum filling process by using a through-hole gasket structure that allows liquid crystal to be introduced directly into the panel gap without requiring vacuum evacuation. This removes the time-consuming vacuum step for large panels while maintaining complete filling through capillary forces acting on the liquid crystal introduced via the through-hole.
2Quantity of substance
If traditional vacuum process is used with flexible substrates, then liquid crystal can be filled, but trapped air causes the empty cell to expand and damage the cell or gasket
Solution Approach 1:
The invention removes the vacuum step from the process when using flexible substrates, extracting the harmful effect of air expansion. Instead of evacuating air and risking cell ballooning, liquid crystal is introduced directly through the through-hole gasket structure, and air is naturally displaced during the filling process without creating pressure differential that causes expansion.
Solution Approach 2:
The through-hole gasket is pre-formed and positioned before substrate assembly, creating a controlled pathway for liquid crystal introduction. This preliminary structure prevents air trapping and cell expansion by allowing air to escape through the same through-hole as liquid crystal enters, maintaining structural integrity during filling.
3Ease of manufacture
If glass substrates are used in traditional processes, then manufacturing is well-established, but flexibility and light-weight requirements cannot be met
Solution Approach 1:
The invention changes the substrate material parameter from rigid glass to flexible plastic materials. The through-hole gasket structure and alignment layer coating process are adapted to work with flexible substrates, maintaining manufacturing feasibility while achieving the desired flexibility and light-weight properties for applications like eyewear and wearable displays.
4Ease of manufacture
If polymer encapsulated liquid crystal is used to prevent flow, then manufacturing becomes easier, but optical clarity deteriorates due to light scattering
Solution Approach 1:
The invention extracts the polymer encapsulation step from the manufacturing process. Instead of encapsulating liquid crystal in polymer droplets which scatter light, the patent uses a through-hole gasket structure to contain and control liquid crystal flow. This removes the harmful light scattering effect while maintaining ease of manufacture through the simplified gasket-based containment approach.
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 method enables the production of flexible liquid crystal devices with improved uniformity and optical clarity, suitable for large-scale applications, while avoiding the limitations of traditional vacuum-based processes and enhancing the durability and flexibility of the devices.
Implementation Method 1
The flexible cell has substrates separated by a controlled distance maintained by spacers
Implementation Method 2
The liquid crystal then fills the gap inside the panel due to capillary forces
Implementation Method 3
using a lamination roller to mate the second substrate with the first substrate and to roll-fill the cell with the electro-optic material
Data Source
AI summary
Provided is a flexible cell unit and a method of manufacturing the same. The cell unit includes first and second substrates separated by a controlled distance maintained by spacers, filled with an electro-optic material and enclosed by a border seal. The method includes providing two sheets to form the first and second substrates, where at least one of the sheets is flexible, depositing an electro-optic material on at least one substrate, and roll-filling the cell by using one or more lamination rollers to pair the first and second substrates to within the controlled distance of each other and filling the controlled distance with the electro-optic material.