LCD Panel Polymerization Using Dual-Wavelength UV
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Solution Overview
Problem
LCD panels using polymer-stabilizing alignment technology suffer from issues like Mura (non-uniform luminance) and image sticking due to incomplete polymerization of photosensitive monomers, which persist even with the addition of light initiators during manufacturing.
Innovation Solution
Implementing a two-step polymerization process where the second polymerization reaction uses ultraviolet light with a larger wavelength and includes at least one photosensitive monomer with an absorption peak greater than 300 nm to absorb and polymerize residual monomers, reducing their presence in the liquid crystal material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photosensitive monomers are polymerized using conventional ultraviolet irradiation, then the liquid crystal alignment is formed, but residual photosensitive monomers remain causing image sticking and Mura effects
Solution Approach 1:
The patent divides the polymerization process into two distinct stages: first polymerization using conventional UV irradiation (300-400nm) to form initial alignment, and second polymerization using far-UV irradiation (200-300nm) to eliminate residual monomers. This segmentation allows each stage to serve a specific function, resolving the contradiction between forming alignment and removing residuals.
Solution Approach 2:
The first polymerization step performs preliminary alignment formation before the second step addresses residual monomer elimination. By preparing the alignment structure first, the subsequent far-UV treatment can focus solely on polymerizing remaining monomers without disrupting the established alignment pattern.
2Manufacturing precision
If light initiator is added to initiate polymerization reaction, then polymerization completeness is improved, but image sticking problem persists due to residual photosensitive monomers
Solution Approach 1:
The patent changes the wavelength parameter of UV irradiation from conventional ranges (300-400nm) to far-UV range (200-300nm) in the second polymerization step. This parameter change enables effective polymerization of residual monomers that were not fully polymerized in the first step, thereby eliminating image sticking while maintaining alignment quality.
3Object-generated harmful factors
If photosensitive monomers are completely polymerized, then image sticking is reduced, but the alignment polymer formation may be affected
Solution Approach 1:
By segmenting the polymerization into two steps with different UV wavelengths, the patent ensures that the first step forms the alignment polymer structure while the second step completes monomer polymerization. This segmentation prevents disruption of the alignment structure while achieving complete polymerization.
Solution Approach 2:
The alignment polymer formation is performed as a preliminary action in the first step, establishing a stable structure before the second step eliminates residual monomers. This sequence ensures that complete polymerization does not compromise the already-formed alignment structure.
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 effectively minimizes residual photosensitive monomers, improving luminance uniformity and reducing image sticking, as demonstrated by experimental results showing reduced residual monomer concentrations and enhanced display quality.
Implementation Method 1
at least one photosensitive monomer whose absorption peak is larger than 300 nm is added to the liquid crystal material which is used for absorbing the ultra-violet in the second polymerization reaction
Implementation Method 2
the absorption peak of at least one photosensitive monomer is larger than 300 nm
Data Source
AI summary
A method for manufacturing LCD panels includes providing upper and lower substrates; interposing a liquid crystal material composed of at least one liquid crystal molecule and at least two photosensitive monomers between the upper and lower substrates, at least one first photosensitive monomer having an absorption peak larger than 300 nm and at least one second photosensitive monomer having an absorption peak smaller than 300 nm; applying a voltage between the upper and lower substrates and irradiating with ultra-violet radiation having a first wavelength larger than 300 nm for a first time interval for polymerizing most first photosensitive monomers to provide an alignment polymer; and separately irradiating with ultra-violet radiation having a second wavelength for a second time interval, the second wavelength being larger than the first wavelength. The Irradiating steps are separate and, when irradiating with the first wavelength precedes irradiating with the second wavelength, residual monomers are reduced.