LCD Testing Apparatus Using Polarized Light and CCD Camera
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Solution Overview
Problem
The existing methods for testing liquid crystal display (LCD) devices are inefficient, relying on human inspection to detect defects such as stains, which can be time-consuming and prone to errors, especially for larger devices.
Innovation Solution
An LCD device testing apparatus and method utilizing a stage with a floating structure, a backlight unit with polarizing plates, and a CCD camera to automatically scan and analyze the liquid crystal panel for brightness differences, enabling efficient detection of defects by polarizing light and comparing it to a reference value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If human inspection is used to detect defects in LCD devices, then the testing process is simple, but test efficiency is low and detection accuracy is poor
Solution Approach 1:
The patent replaces human visual inspection with an automated optical testing system consisting of a light source, polarizing plates, and CCD camera. The system uses optical principles to detect brightness differences caused by defects in the liquid crystal panel, eliminating the need for human inspectors and significantly improving test efficiency and consistency.
Solution Approach 2:
The patent creates an optical copy of the liquid crystal panel by projecting light through the panel onto a CCD camera sensor. This optical copy captures brightness variations across the panel surface, allowing digital analysis of defects without physical contact with the actual display device.
2Measurement precision
If human inspection is used to detect defects, then the equipment is simple, but measurement precision is insufficient especially for large-sized devices
Solution Approach 1:
The patent replaces human visual inspection with an automated optical measurement system that uses a light source to illuminate the liquid crystal panel and a CCD camera to capture brightness distributions. This system can precisely measure brightness differences across large display areas with high spatial resolution, overcoming the limitations of human inspection.
Solution Approach 2:
The patent introduces polarizing plates as intermediary components between the light source and the liquid crystal panel. These plates control the polarization state of light to enhance the visibility of defects by creating specific optical interference patterns that make brightness variations more pronounced and easier to detect.
3Productivity
If automated optical testing is implemented, then test efficiency improves, but device complexity increases
Solution Approach 1:
The patent divides the testing apparatus into distinct functional modules: a light source unit, a polarizing plate assembly, and a CCD camera system. Each module performs a specific function in the optical testing process, making the overall system easier to design, assemble, and maintain while achieving automated defect detection.
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 significantly improves test efficiency by automating defect detection, reducing reliance on human judgment and enabling faster identification of defective panels, particularly for larger LCD devices.
Implementation Method 1
a lower polarizing plate formed on the protective film to firstly polarize light emitted from the light source in a fixed axis direction
Implementation Method 2
an upper polarizing plate separated from the upper surface of the liquid crystal panel by a fixed distance to secondarily polarize light from the liquid crystal panel in the fixed axis direction
Implementation Method 3
The LCD device applies a voltage to the liquid crystal cell and changes its molecular alignment. This converts several optical properties such as birefractivity, light polarization, and light dispersion in the liquid crystal cell into a visual variation
Implementation Method 4
This converts several optical properties such as birefractivity, light polarization, and light dispersion in the liquid crystal cell into a visual variation
Data Source
AI summary
A liquid crystal display (LCD) device testing apparatus that comprises a stage configured in an air-floating structure to feed a liquid crystal panel including combined upper and lower substrates, a backlight unit configured to include a light source for an emission of light disposed under the stage, a protective film formed to encompass and protect the light source, and a lower polarizing plate formed on the protective film to firstly polarize light emitted from the light source in a fixed axis direction, an upper polarizing plate separated from the upper surface of the liquid crystal panel by a fixed distance to secondarily polarize light from the liquid crystal panel in the fixed axis direction; and a charge couple device (CCD) camera disposed on the upper polarizing plate to scan an image on the liquid crystal panel using light secondarily polarized by the upper polarizing plate.