Divisional Exposure Apparatus for Uniform PAC Layer in COT Displays
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Solution Overview
Problem
In large-size liquid crystal displays with a COT structure, the formation of a uniform PAC layer using divisional exposure is challenging due to thickness differences in the overlap regions, leading to issues like black spots and reduced brightness, especially when using halftone processes.
Innovation Solution
A divisional exposure apparatus with blades that control light exposure energy by dividing the overlap region into specific areas with different illumination intensity profiles, ensuring consistent illumination across the overlap region, thereby reducing thickness variations and improving uniformity of the PAC layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If divisional exposure is used to expose large-size substrates, then productivity is improved, but manufacturing precision deteriorates due to thickness differences in the PAC layer at overlap regions
Solution Approach 1:
The patent applies local quality by differentiating illumination intensity control between overlap regions and non-overlap regions. Specifically, the control unit adjusts the illumination intensity of the light source when exposing overlap regions compared to non-overlap regions, ensuring that the cumulative illumination energy results in uniform PAC layer thickness across the entire substrate including overlap areas.
2Area of stationary object
If multiple scans are performed for divisional exposure, then large-area coverage is achieved, but illumination intensity variation occurs in overlap regions causing black spots
Solution Approach 1:
The patent implements feedback control where the control unit monitors the scan position and overlap region identification, then dynamically adjusts the illumination intensity based on real-time exposure conditions. The control unit determines whether the current exposure area is an overlap region or non-overlap region and modifies the light source intensity accordingly to maintain uniform illumination distribution.
3Ease of manufacture
If halftone process is used with divisional exposure, then color filter formation is achieved, but thickness variation in PAC layer increases due to cumulative illumination effects
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the illumination intensity parameter during the exposure process. The control unit changes the light source intensity based on the identified region type (overlap or non-overlap) and scan number, ensuring that the cumulative illumination energy across multiple scans results in consistent PAC layer thickness despite the halftone process requirements.
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
The solution effectively reduces the number of black spots and ensures consistent cell gap across the display, enhancing image quality and brightness by maintaining uniform illumination intensity profiles in the overlap regions.
Implementation Method 1
a blade that is located at one side of a light illumination pattern in an overlap region and that controls light exposure energy (illumination intensity) according to position
Implementation Method 2
forming a photo-acrylic layer using exposure
Data Source
AI summary
Disclosed are a divisional exposure apparatus which allows for forming a PAC layer uniformly on RGBW subpixels by a single mask process, using divisional exposure, in a large-size liquid crystal display with a COT structure, and a method of manufacturing a liquid crystal display using the same. To this end, the sum of illumination intensities at the center of an overlap region is controlled in the range of 120% to 130%, and gradually increases from 100% at the edge (boundary) of the overlap region. Accordingly, the cell gap between the RGB subpixels and the W subpixel is made uniform, thus preventing the problem of spots.