Waveguide Light-Shielding Film Inkjet Deposition

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Solution Overview

Problem

Conventional methods for forming a light-shielding film on the cut surface of waveguides, such as contact type printing, struggle to achieve precise coating on narrow, curved, or inclined surfaces, leading to inadequate light leakage suppression and external light interference in wearable augmented reality devices.

Innovation Solution

A waveguide with a light-shielding film formed using a curable ink composition, specifically a combination of carbon black, epoxy compounds, and oxetane, applied via inkjet printing to achieve a thickness of 2 to 10 μm and optical density of 0.7 to 1.0, allowing for effective light blocking and adhesion on various surface shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If contact type printing is used to form a light-shielding film, then the coating process is simple, but it is difficult to achieve precise coating on narrow, curved, or inclined surfaces

Engineering Contradiction:

Improvecoating process simplicityVSAvoidcoating precision on narrow surfaces

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces contact type printing (mechanical system) with inkjet printing (non-contact system). The inkjet printing head deposits curable ink composition onto the waveguide cut surface without physical contact, enabling precise coating on narrow, curved, and inclined surfaces while maintaining ease of manufacture through automated deposition processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a curable ink composition as an intermediary material that can be precisely deposited and then cured to form the light-shielding film. This intermediary allows for controlled application on complex geometries, bridging the gap between simple deposition processes and precise coating requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the light-shielding film thickness is increased to suppress light leakage, then light shielding performance improves, but the film thickness becomes difficult to control precisely

Engineering Contradiction:

Improvelight leakage suppressionVSAvoidfilm thickness control

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent changes the key parameter from film thickness to optical density for specifying light-shielding performance. By controlling the optical density of the curable ink composition and using precise inkjet deposition, the system achieves consistent light leakage suppression without relying on thick films, thereby improving thickness control precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional coating methods with inkjet printing, which offers superior thickness control through digital precision in ink deposition. The non-contact inkjet system can accurately control the amount of curable ink composition applied, ensuring consistent film thickness and optical density across complex waveguide surfaces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If conventional coating methods are used on curved or inclined surfaces, then the process is simple, but precise coating cannot be achieved

Engineering Contradiction:

Improvecoating process simplicityVSAvoidcoating precision on curved surfaces

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces contact type printing with non-contact inkjet printing, which can accurately deposit curable ink composition on curved and inclined surfaces without mechanical constraints. The inkjet system maintains ease of manufacture through automated operation while achieving precise coating on complex geometries that are inaccessible to contact methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 prevents light leakage and external light ingress, enhancing image quality and user experience by providing a thin, high-optical-density light-shielding film with excellent adhesion properties, suitable for both flat, curved, and inclined surfaces.

Implementation Method 1

b) curing a pattern of the light-shielding film to form a light-shielding film having an optical density (OD) of 0.7 to 1.0 based on the light-shielding film of a thickness of 1.0 μm

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Implementation Method 2

a waveguide having a light-shielding film with a thickness of 2 to 10 μm having an optical density (OD) of 0.7 to 1.0

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS10739515B2Waveguide having light shielding film formed thereon and manufacturing method therefor

Publication Date: 2020.08.11 LG CHEM LTD

AI summary

A waveguide having a light-shielding film formed on a cut surface of an edge side of the planar waveguide, the light-shielding film having a thickness of 2 to 10 μm and an optical density (OD) of 0.7 to 1.0 based on a light-shielding film thickness of 1.0 μm, and a method for manufacturing the same.