LED Light Irradiation Device for Photo-Alignment
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Solution Overview
Problem
Existing exposure machines using long-arc mercury lamps for photo-alignment in liquid crystal panel manufacturing face issues with light wavelength deviation from photosensitive characteristics, leading to excessive exposure and reduced efficiency, along with challenges in controlling light irradiation angles and increasing costs due to complex optical systems.
Innovation Solution
A light irradiation device with a simple configuration, utilizing a plurality of LEDs as a light source and a polarizing element to apply light to a workpiece, where the optical axis of each LED is tilted at a specific angle, and the light distribution angle is controlled to ensure effective irradiation with minimal deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a long-arc mercury lamp is used as a light source for photo-alignment, then the exposure machine can provide sufficient light intensity, but the light contains many wavelengths deviating from the photosensitive characteristics of the exposure material, causing excessive exposure and reduced efficiency
Solution Approach 1:
The patent extracts only the necessary wavelength component (365±10nm) from the broad-spectrum mercury lamp light using a band-pass filter. This filter removes wavelengths both shorter and longer than the photosensitive characteristics of the exposure material, preventing excessive exposure while maintaining sufficient light intensity for photo-alignment.
Solution Approach 2:
The patent introduces a band-pass filter as an intermediary component between the light source and the workpiece. This filter mediates the interaction by selectively transmitting only the photosensitive wavelength range (365±10nm) while blocking other wavelengths, thus resolving the contradiction between providing sufficient light intensity and preventing excessive exposure.
2Loss of energy
If a selective wavelength reflection film or band-pass filter is used to cut light beams of wavelengths deviating from photosensitive characteristics, then excessive exposure is prevented, but the machine cost increases due to high degree of accuracy requirements
Solution Approach 1:
The patent specifies a wavelength bandwidth of ±10nm around the central wavelength of 365nm, which provides sufficient spectral selectivity to prevent excessive exposure while maintaining reasonable manufacturing tolerances. This parameter optimization balances the contradiction between preventing excessive exposure and controlling device complexity.
3Quantity of substance
If light from a long-arc mercury lamp is used for photo-alignment, then sufficient light quantity is provided, but the light diffuses widely making it difficult to control the irradiation angle, reducing photo-alignment effectiveness
Solution Approach 1:
The patent uses multiple linear arrangement LEDs instead of a single point source, which segments the light source into discrete elements. This segmentation, combined with the tilted optical axis configuration, enables better control over the light distribution pattern and irradiation angle while maintaining sufficient light quantity for photo-alignment.
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 enables a photo-alignment process that handles a large quantity of light with an effective irradiation angle, improving the stability of pretilt angles and alignment states in liquid crystal panels, while maintaining a simple and cost-effective configuration.
Implementation Method 1
a light source with a plurality of LEDs
Implementation Method 2
a polarizing element that receives light from the light source and applies the light transmitted through the polarizing element to a workpiece
Data Source
AI summary
A light irradiation device for an exposure apparatus allowing implementation of photo-alignment process with a simple configuration is provided. The light irradiation device is configured using a light source with a plurality of LEDs, and a polarizing element that receives light from the light source and applies the light transmitted through the polarizing element to a workpiece. An optical axis of each of the LEDs is set in such a manner as to have a first angle θ1 to the workpiece. A second angle θ2 as an angle half of a light distribution angle of the light emitted from each of the LEDs is set smaller than the first angle θ1.