Aluminum Diffusion Element Reflectance and Reliability

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Solution Overview

Problem

Existing light source devices with laser light sources face issues with speckle noise and a decrease in reflectance due to temperature increases, particularly when using aluminum as the material for the reflection film, which affects the reliability and performance of the diffusion element.

Innovation Solution

A light source device is designed with a diffusion element featuring a base material of aluminum alloy, a reflection film composed of high purity aluminum, and a dielectric multilayer film, which enhances reflectance and reliability by maintaining reflectance comparable to silver while using aluminum, and includes a rotating device to optimize light diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If aluminum is used as the reflection film material to suppress metal aggregation, then reliability is improved, but reflectance decreases

Engineering Contradiction:

Improvereliability of diffusion elementVSAvoidreflectance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent uses a composite structure consisting of an aluminum-based reflection film with specific aluminum content (5-95 wt%) combined with a dielectric multilayer film. This composite material approach allows the system to achieve both high reliability (by using aluminum instead of silver) and high reflectance (through the optimized composite structure and dielectric layers) simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the aluminum content parameter within a specific range (5-95 wt%) to balance aggregation suppression and reflectance. By controlling this compositional parameter and combining it with a dielectric multilayer structure, the system achieves both improved reliability and maintained reflectance performance.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If silver is used as the reflection film material, then reflectance is improved, but metal aggregation increases

Engineering Contradiction:

ImprovereflectanceVSAvoidreliability of diffusion element

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent replaces expensive silver with aluminum, which is more abundant and cost-effective. Although aluminum has lower inherent reflectance, the combination with dielectric multilayer compensation and optimized composition creates a durable, cost-effective alternative that maintains performance while improving reliability through resistance to aggregation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If the temperature of the reflection film increases due to light irradiation, then metal aggregation accelerates, but reflectance decreases

Engineering Contradiction:

Improvetemperature of reflection filmVSAvoidreliability of diffusion element

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent converts the harmful effect of temperature increase (which accelerates aggregation) into a beneficial outcome by using aluminum's higher aggregation energy. The same temperature increase that would harm silver-based films actually demonstrates aluminum's superior thermal stability, as the material resists aggregation even under elevated temperature conditions, thereby improving reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 suppresses the decrease in reflectance and ensures the reliability of the diffusion element, maintaining comparable reflectance to silver-based devices for blue light within specific wavelength and angle ranges, and significantly improves the durability and performance of the light source device.

Implementation Method 1

a reflection film that is provided along the uneven structure and is composed of aluminum

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

the blue light is light on the short wavelength side in the visible light wavelength band, and has a relatively large action of accelerating a metal aggregation phenomenon

Methodology Applied

Scientific EffectMetal aggregation phenomenon: Coagulation

Implementation Method 3

the dielectric multilayer film may be composed of two or more types of materials having mutually different refractive indices

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 4

a diffusion element configured to diffuse the light emitted from the light source

Methodology Applied

Scientific EffectLight diffusion: Scattering

Data Source

PatentUS10585342B2Light source device and projector

Publication Date: 2020.03.10 SEIKO EPSON CORP

AI summary

A light source device according to the invention includes a light source configured to emit blue light having a wavelength band of 37 nm or less and a diffusion element configured to diffuse the light emitted from the light source. The diffusion element includes a base material that has an uneven structure and is composed of a metal, a reflection film that is provided along the uneven structure and is composed of aluminum, and a dielectric multilayer film provided on the reflection film.