Half-tone Photomask for Uniform Liquid Crystal Pre-tilt Angles
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Solution Overview
Problem
The production of large-sized liquid crystal display panels on a mother substrate faces challenges with inconsistent pre-tilt angles of liquid crystals due to different numbers of pixels per inch, leading to issues like poor diffusion and broken bright spots, which reduce display quality and increase production costs.
Innovation Solution
An apparatus using a half-tone photomask is employed to regulate the ultraviolet light transmittance for chips with varying pixel densities, ensuring uniform pre-tilt angles across different pixel regions, thereby improving optical alignment and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultraviolet irradiation is applied uniformly to all chips on the mother substrate, then the alignment process is simple and fast, but chips with different pixel densities obtain inconsistent pre-tilt angles leading to poor diffusion and broken bright spots
Solution Approach 1:
The patent applies local quality by differentiating the ultraviolet irradiation treatment based on chip characteristics. Chips with different pixel densities (pixels per inch) receive different irradiation doses - higher pixel density chips receive lower irradiation while lower pixel density chips receive higher irradiation. This localized differentiation resolves the contradiction by maintaining uniform process simplicity while achieving precise pre-tilt angle consistency across diverse chip types.
Solution Approach 2:
The patent changes the irradiation parameter (ultraviolet dose) according to chip pixel density. By adjusting the irradiation intensity or exposure time as a variable parameter based on the specific chip type, the system achieves consistent pre-tilt angles across different chip specifications without complicating the overall alignment process, thus resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If different irradiation conditions are applied to chips with different pixel densities, then pre-tilt angle consistency is improved, but the alignment process complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-categorizing chips according to their pixel density specifications before the alignment process. This preliminary classification allows the system to apply appropriate irradiation conditions automatically based on chip type, achieving precise pre-tilt angle control without requiring complex real-time adjustments during the alignment process itself.
Solution Approach 2:
The patent applies local quality by tailoring the ultraviolet irradiation parameters to specific chip groups based on their pixel density. This localized approach maintains process simplicity by treating chips in groups rather than requiring individual customization, thus resolving the contradiction between achieving manufacturing precision and avoiding excessive device complexity.
3Manufacturing precision
If rubbing cloth method is used to form pre-tilt, then alignment film formation is achieved, but outside materials are introduced and electrostatic charges are generated reducing productivity
Solution Approach 1:
The patent replaces the mechanical rubbing cloth method with a non-contact ultraviolet irradiation method to form the pre-tilt in the alignment film. This substitution eliminates the harmful effects of mechanical contact (outside material introduction and electrostatic charge generation) while maintaining the essential function of pre-tilt formation, thus resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent introduces ultraviolet light as an intermediary to achieve pre-tilt formation without direct mechanical contact. The ultraviolet irradiation acts as a mediator that transfers the alignment information to the liquid crystal molecules through the alignment film, replacing the need for physical rubbing and thereby eliminating productivity-reducing side effects while maintaining alignment quality.
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 apparatus effectively maintains consistent pre-tilt angles for liquid crystals across different pixel regions, preventing issues like poor diffusion and broken bright spots, and enhancing the overall display quality and production efficiency.
Implementation Method 1
a photo-reactive material is provided on a substrate, and a tilted ultraviolet irradiates a surface of the photo-reactive material. The pre-tilt of the alignment film is formed according to the irradiation direction
Implementation Method 2
An apparatus using a half-tone photomask is employed to regulate the ultraviolet light transmittance for chips with varying pixel densities
Data Source
AI summary
Disclosed is an apparatus for improving optical alignment of panels manufactured on a same mother substrate. The technical defect in the prior art which affects product quality can be eliminated. The apparatus for improving optical alignment of panels manufactured on a same mother substrate includes a mother substrate (1), N columns of chips in a first group (2), N columns of chips in a second group (3), and a photomask (4). The N columns of chips in the first group (2) and the N columns of chips in the second group (3) are arranged in an alternate manner and are arranged on the mother substrate (1). An area of the chips in the second group (3) is larger than an area of the chips in the first group (2). The photomask (4) covers the N columns of chips in the first group (2) and the N columns of chips in the second group (3) so that ultraviolet irradiates the N columns of chips in the first group (2) and the N columns of chips in the second group (3) after passing through the photomask (4). N is a positive integer. The apparatus can be used in manufacturing of TFT-LCD.