Wavelength Conversion Element with Intermediate Layer for Fluorescence Efficiency

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Solution Overview

Problem

Existing light source devices with phosphor layers suffer from inefficient use of fluorescence due to reflection losses, as a portion of the fluorescence is converted into heat and absorbed when reflected by the light reflective substrate, leading to reduced luminance in projectors.

Innovation Solution

A wavelength conversion element is designed with a substrate, a reflecting section, a wavelength conversion layer, and a reflecting surface that totally reflects light at an angle equal to or greater than the critical angle, utilizing an intermediate layer with a lower refractive index than the wavelength conversion layer to minimize light loss and enhance heat radiation, and optionally featuring a dichroic mirror for transmissive configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a light reflective substrate is used to reflect fluorescence, then the fluorescence can be redirected for use, but a portion of the fluorescence is converted into heat and absorbed, reducing efficiency

Engineering Contradiction:

Improvefluorescence use efficiencyVSAvoidfluorescence loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

An intermediate layer with lower refractive index than the wavelength conversion layer is introduced between the wavelength conversion layer and the reflecting section. This intermediate layer creates a reflecting surface at its interface with the wavelength conversion layer, enabling total internal reflection of fluorescence while reducing direct contact between fluorescence and the light reflective substrate, thereby minimizing heat absorption and energy loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter is strategically utilized by selecting an intermediate layer material with a lower refractive index than the wavelength conversion layer. This parameter change creates the optical condition for total internal reflection at the interface, allowing fluorescence to be reflected efficiently without being absorbed by the light reflective substrate, thus improving energy efficiency.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If fluorescence is reflected by the light reflective substrate, then light can be redirected, but light loss occurs due to heat absorption

Engineering Contradiction:

ImproveluminanceVSAvoidlight loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The intermediate layer serves as a mediator that enables the reflecting surface to function effectively. By positioning this layer between the wavelength conversion layer and the light reflective substrate, it creates an interface that reflects fluorescence through total internal reflection, preventing direct absorption by the substrate and reducing light loss, thereby maintaining high luminance and productivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index difference between the wavelength conversion layer and the intermediate layer, which could potentially cause optical losses, is converted into a beneficial reflecting surface through total internal reflection. This transforms what could be a source of light loss into an efficient light redirection mechanism, improving overall system productivity.

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

This configuration significantly increases the use efficiency of fluorescence, resulting in higher luminance and improved projector performance by reducing light absorption and maintaining efficient heat management.

Implementation Method 1

a reflecting surface disposed between a surface of the wavelength conversion layer on an opposite side to the reflecting section and the reflecting section, and adapted to totally reflect light having been input at an angle no smaller than a critical angle out of the fluorescence

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a wavelength conversion layer disposed on an opposite side of the reflecting section to the substrate, and emitting fluorescence in response to irradiation with excitation light

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS9874741B2Wavelength conversion element, light source device, and projector

Publication Date: 2018.01.23 SEIKO EPSON CORP

AI summary

A wavelength conversion element includes a substrate, a reflecting section disposed on one surface side of the substrate, a wavelength conversion layer disposed on an opposite side of the reflecting section to the substrate, and emitting fluorescence in response to irradiation with excitation light, and a reflecting surface disposed between a surface of the wavelength conversion layer on an opposite side to the reflecting section and the reflecting section, and adapted to totally reflect light having been input at an angle no smaller than a critical angle out of the fluorescence.