Wavelength Conversion Element with Intermediate Layer for Projector Light Efficiency

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing light source devices for projectors, which use a dichroic layer and a fluorescent layer on a transparent substrate, suffer from inefficient use of fluorescence due to the P-polarized component passing through the dichroic layer and substrate, leading to reduced light utilization.

Innovation Solution

A wavelength conversion element is introduced, comprising a substrate, an intermediate layer with a refractive index less than the substrate, a dichroic layer, and a fluorescent layer. The dichroic layer has a multi-layer film structure that alternately laminates films with different refractive indices, and the intermediate layer totally reflects light satisfying the Brewster condition, ensuring efficient use of light by reflecting or transmitting specific wavelength bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a dichroic layer and fluorescent layer are laminated on a transparent substrate, then the device structure is simple and easy to manufacture, but part of the fluorescence (P-polarized component) passes through the dichroic layer and substrate reducing light use efficiency

Engineering Contradiction:

Improveease of manufactureVSAvoidlight use efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

An intermediate layer with refractive index N is introduced between the substrate and dichroic layer. This intermediate layer acts as an optical mediator that enables total reflection of P-polarized light at the dichroic layer interface, preventing the harmful transmission of fluorescence through the substrate while maintaining the simple lamination structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter of the intermediate layer is specifically controlled (N < nsinθ1, where θ1 is the Brewster angle) to change the optical parameters of the system. This parameter change enables the intermediate layer to reflect P-polarized light through total internal reflection, converting the previously harmful transmission into useful reflection and improving light use efficiency.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the dichroic layer uses a multi-layer film structure with alternating refractive indices, then light extraction efficiency is improved, but the device complexity increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The dichroic layer is segmented into multiple thin films with alternating high and low refractive indices. This segmentation creates a multi-layer interference structure that enhances light extraction efficiency through constructive interference of reflected waves, while each individual layer remains relatively simple in structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dichroic layer uses composite material structure combining materials with different refractive indices in alternating layers. This composite structure optimizes optical performance by creating impedance matching and interference effects that improve light extraction, while the modular nature of composite materials facilitates manufacturing.

Inventive Principle:

Principle #40Composite materials

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 enhances light use efficiency by reducing the transmission of unwanted light components, allowing for either transmissive or reflective extraction of the converted light, thereby improving the overall light output in projector devices.

Implementation Method 1

the intermediate layer totally reflects the light with the second wavelength band in the interface between the intermediate layer and the dichroic layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

part of fluorescence, P-polarized component, satisfying a brewster condition passes through the dichroic layer and the substrate

Methodology Applied

Scientific EffectBrewster condition: Brewster's Angle

Implementation Method 3

a fluorescent layer that is provided on the dichroic layer and that is excited by light with a first wavelength band and thereby emits light with a second wavelength band different from the first wavelength band

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS9785040B2Wavelength conversion element, light source device, and projector

Publication Date: 2017.10.10 SEIKO EPSON CORP

AI summary

A wavelength conversion element includes: a substrate; an intermediate layer that is provided on the substrate and has a refractive index less than a refractive index of the substrate; a dichroic layer that is provided on the intermediate layer; and a fluorescent layer that is provided on the dichroic layer and that is excited by light with a first wavelength band and thereby emits light with a second wavelength band different from the first wavelength band.