Rubbing Angle Measurement for LCD Substrates
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Solution Overview
Problem
Current methods face challenges in accurately controlling the rubbing angle of substrates during liquid crystal display and optical film manufacturing, particularly due to dispersion in rubbing cloth conditions and the need for non-destructive, high-accuracy measurements post-rubbing to ensure optimal optical characteristics.
Innovation Solution
A rubbing angle measurement system utilizing a light source, polarizer, analyzer, focusing optical system, and imaging means to detect signals with intense periodicity under Crossed Nicols, enabling two-dimensional fast Fourier transformation or differential processing for precise angle measurement, which can be fed back to improve the rubbing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rubbing treatment is applied to substrates during liquid crystal display manufacturing, then alignment control direction is established, but rubbing angle accuracy deteriorates due to dispersion in rubbing cloth conditions
Solution Approach 1:
The patent applies preliminary action by measuring the rubbing angle immediately after the rubbing treatment is completed, before any subsequent processes that might alter the alignment. This timing ensures that the measurement captures the actual rubbing angle achieved, allowing for immediate feedback and correction if necessary.
Solution Approach 2:
The patent implements feedback by using the measured rubbing angle information to adjust and optimize subsequent manufacturing processes. The measurement results are fed back to control the rubbing process parameters, such as rubbing cloth selection, rubbing pressure, and rubbing speed, to achieve the desired alignment accuracy despite variations in rubbing conditions.
2Measurement precision
If conventional measurement methods are used after rubbing, then rubbing angle can be assessed, but measurement time increases and productivity decreases
Solution Approach 1:
The patent replaces conventional mechanical or time-consuming optical measurement methods with a streamlined optical measurement system that uses polarized light and image processing. This substitution enables rapid, non-contact measurement of the rubbing angle, significantly reducing measurement time while maintaining high precision.
Solution Approach 2:
The patent changes the measurement parameters by using specific polarization angles (0° and 45° relative to the rubbing direction) and analyzing the intensity distribution of transmitted light. This parameter optimization allows for fast automated image processing and rubbing angle calculation, improving both speed and accuracy.
3Reliability
If high-accuracy rubbing angle measurement is implemented, then optical characteristics improve, but device complexity increases due to additional measurement and control systems
Solution Approach 1:
The patent achieves universality by designing a measurement system that can evaluate the rubbing angle for both TFT substrates and CF substrates using the same optical setup and processing methodology. This multi-functional approach reduces the need for separate measurement systems for different substrate types, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent uses optical copying by capturing an image of the substrate through the polarizer and analyzer system, then analyzing the intensity distribution in the copied image to determine the rubbing angle. This non-contact optical copying method avoids the need for physical probes or complex mechanical measurement devices, simplifying the overall system.
4Ease of manufacture
If rubbing angle is not precisely controlled, then manufacturing process is simpler, but optical performance of liquid crystal panels deteriorates
Solution Approach 1:
The patent enables self-service by implementing an automated measurement and feedback system that reduces the need for manual intervention in the rubbing process. The system automatically measures the rubbing angle, compares it with target values, and provides feedback for adjustments, allowing the manufacturing process to self-correct and maintain high optical performance without increasing operational complexity.
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
Enables non-destructive, high-accuracy measurement of rubbing angles at 0.1° or higher, allowing for immediate feedback and optimization of the rubbing process, thereby improving the optical performance and stability of liquid crystal panels and optical films.
Implementation Method 1
A rubbing angle measurement system utilizing a light source, polarizer, analyzer, focusing optical system, and imaging means to detect signals with intense periodicity under Crossed Nicols
Implementation Method 2
A rubbing angle measurement system utilizing a light source, polarizer, analyzer, focusing optical system, and imaging means
Data Source
AI summary
A rubbing angle measuring equipment of the invention includes an light source unit, a measuring optical system, an imaging means, and an image evaluation means in which the measuring optical system is adapted such that a light from the light source unit passes by way of an illumination optical system and a polarizer to a rubbed measuring object and further passes by way of an analyzer and a focusing optical system to the imaging means, and the surface of the measuring object is focused to the imaging means, and in which image signals obtained by the imaging means are transmitted to the image evaluation means where signals having an intense periodicity in the image are detected, to measure the rubbing angle of the measuring object in a nondestructive manner, within a short period and at a high accuracy of 0.1° or more.