Oxygen Sensor for Liquid Crystal Cell Vacuum Filling
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Solution Overview
Problem
Large liquid crystal devices face challenges in efficiently evacuating air from their cavities due to the size disparity between fill openings and cavities, leading to potential defects and prolonged filling times, as existing methods rely on pressure sensors that fail to accurately indicate complete evacuation.
Innovation Solution
A method utilizing an oxygen sensor to determine the completion of evacuation in a vacuum chamber, allowing for controlled pressure changes to fill liquid crystal cells efficiently, thereby avoiding unnecessary wait times and ensuring thorough air removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used to determine evacuation completion, then the filling process can be monitored, but the pressure sensors fail to accurately indicate complete evacuation leading to prolonged waiting times
Solution Approach 1:
The patent replaces pressure sensors with an oxygen sensor to detect evacuation completion. The oxygen sensor provides more accurate and rapid detection of when the cavity is sufficiently evacuated, eliminating the need to continue evacuation based on pressure readings and thereby reducing unnecessary waiting time.
Solution Approach 2:
The patent changes the detection parameter from pressure to oxygen concentration. By monitoring oxygen levels instead of pressure, the system can more accurately determine when evacuation is complete, as oxygen depletion provides a clearer and more reliable indicator of cavity evacuation status.
2Reliability
If evacuation is continued to ensure complete air removal, then filling defects are prevented, but the filling time is prolonged
Solution Approach 1:
The patent implements a feedback mechanism using the oxygen sensor to monitor evacuation progress in real-time. When the oxygen level indicates sufficient evacuation, the system automatically stops the evacuation process and proceeds to filling, ensuring both high reliability of filling quality and optimized evacuation time without unnecessary delays.
3Productivity
If the vacuum chamber is evacuated quickly, then productivity is improved, but air trapped inside the cavity may remain causing visible defects
Solution Approach 1:
The patent substitutes pressure-based monitoring with oxygen-based monitoring to achieve both rapid evacuation and complete air removal. The oxygen sensor provides immediate feedback on evacuation completeness, allowing the system to stop evacuation at the optimal moment when the cavity is sufficiently evacuated, thus preventing defects while maintaining high productivity.
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 approach allows for rapid and reliable filling of liquid crystal cells by accurately determining evacuation completion with an oxygen sensor, reducing waiting times and preventing defects, while maintaining safe pressure levels to avoid substrate stress.
Implementation Method 1
a signal indicating the amount of oxygen remaining inside the vacuum chamber is provided by means of an oxygen sensor mounted inside the vacuum chamber
Implementation Method 2
the vacuum chamber is evacuated
Implementation Method 3
Liquid crystal based devices employ a change in the orientation of liquid crystal molecules between two conductive electrodes by applying an electric field which results in a change of their transmittance
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method for filling liquid crystal cells (40) with a medium (30) comprising at least one liquid crystalline material. The liquid crystal cells (40) comprise two substrates (42) joined together with a peripheral seal (44) so that a cavity is formed, wherein the liquid crystal cells (40) comprise at least one fill opening (46). In a first step a) of the method at least one liquid crystal cell (40) is placed inside a vacuum chamber (12). In a subsequent step b) the vacuum chamber (12) is evacuated. After evacuation has been completed, the at least one fill opening (46) of the at least one liquid crystal cell (40) is contacted with the medium (30) in a step c). In a subsequent step d) the pressure in the vacuum chamber (12) is raised, wherein the rising pressure in the vacuum chamber (12) causes the medium (30) to fill the cavity inside the at least one liquid crystal cell (44). A signal indicating the amount of oxygen remaining inside the vacuum chamber (12) is provided by means of an oxygen sensor (20) mounted inside the vacuum chamber (12) and completion of the evacuation of the vacuum chamber (12) is determined based on said signal. Further aspects of the invention relate to an apparatus (10) for filling a liquid crystal cell (40) with a medium (30) comprising at least one liquid crystalline material and to the use of an oxygen sensor (20) in a process for filling liquid crystal cells (40) with a medium (30) comprising at least one liquid crystalline material.