Ring-Shaped Polarized Light Exposure for Alignment Accuracy

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Solution Overview

Problem

Existing exposure methods for forming alignment films in optical elements, such as liquid crystal display devices, face challenges in achieving high pattern accuracy, particularly for small arc patterns, due to limitations in scanning stage resolution and positioning accuracy.

Innovation Solution

An exposure method and device that focus linearly polarized light in a ring shape using an axicon lens or mirror, with relative movement between the film and optical member, and continuous rotation of the polarization direction, to improve pattern accuracy and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a scanning stage is used to scan the spot in at least two dimensions along the surface of the recording medium, then the exposure area can be covered, but the pattern accuracy decreases for small arc patterns due to scanning stage resolution limitations and positioning accuracy issues

Engineering Contradiction:

Improveexposure areaVSAvoidpattern accuracy

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical scanning stage system with an optical field rotation system. Instead of mechanically moving the scanning stage in two dimensions to cover the exposure area, the invention rotates the polarization direction of light and uses field rotation to achieve the same coverage, thereby eliminating positioning accuracy issues and scanning resolution limitations while maintaining full exposure area coverage

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from two-dimensional mechanical scanning to a different dimensional approach by rotating the polarization direction of light and using optical field rotation. This changes the problem from moving the spot in two dimensions along the surface to rotating the optical field and polarization, achieving area coverage through a different dimensional mechanism that avoids mechanical positioning errors

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the scanning stage is moved to scan the spot along the surface of the recording medium, then the entire pattern can be exposed, but undulation occurs on arc patterns due to straightness and positioning accuracy of the scanning stage

Engineering Contradiction:

Improveexposure completenessVSAvoidarc pattern accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical scanning stage with an optical field rotation mechanism. Instead of mechanically moving the stage to expose the entire pattern, the invention uses polarization rotation and optical field rotation to achieve complete exposure, thereby eliminating undulation on arc patterns caused by mechanical straightness and positioning accuracy limitations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If linearly polarized light is focused in a ring shape with an optical member, then the alignment pattern accuracy can be improved, but the device complexity increases due to additional optical components

Engineering Contradiction:

Improvealignment pattern accuracyVSAvoidoptical member complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter of light focusing from conventional spot focusing to ring-shaped focusing using an axicon lens. This parameter change enables improved alignment pattern accuracy through the ring-shaped exposure profile while the axicon lens provides a relatively simple optical structure compared to complex multi-element focusing systems

Inventive Principle:

Principle #35Parameter changes

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 enhances the accuracy of alignment patterns and enables the formation of optically-anisotropic layers with improved concentric exposure patterns, addressing the limitations of traditional scanning methods.

Implementation Method 1

linearly polarized light is focused in a ring shape with an optical member

Methodology Applied

Scientific EffectLight focusing: Lens

Implementation Method 2

rotating a polarization direction of the linearly polarized light

Methodology Applied

Scientific EffectPolarization rotation: Polarisation

Implementation Method 3

expose a film including a compound having a photo-aligned group

Methodology Applied

Scientific EffectPhotoalignment: Photopolymerisation

Data Source

PatentUS20240248405A1Exposure method, exposure device, and method of manufacturing optically-anisotropic layer

Publication Date: 2024.07.25 FUJIFILM CORP

AI summary

Provided is an exposure method and an exposure device for obtaining a photo-alignment film where the accuracy of an alignment pattern is high, and a method of manufacturing an optically-anisotropic layer. Provided is an exposure method in which linearly polarized light is focused in a ring shape with an optical member to expose a film including a compound having a photo-aligned group, the method including: an exposure step of relatively moving the film and the optical member in an optical axis direction of the optical member while rotating a polarization direction of the linearly polarized light.