Stacked Fluorescent Light Source for Projector Color Gamut

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Solution Overview

Problem

Existing light sources for projectors face challenges in balancing emission spectra for red, green, and blue wavelength regions, leading to inefficiencies and poor color reproducibility, particularly in achieving standard color gamuts like DCI and sRGB.

Innovation Solution

A light source apparatus utilizing a wavelength conversion member with a first and second fluorescent substance, where the first substance emits light in a second wavelength region upon excitation, and the second substance, stacked on top, emits light in a third wavelength region, effectively enhancing color reproducibility and efficiency by adjusting the emission spectra.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single fluorescent substance is used for wavelength conversion, then the device complexity is reduced, but the color reproducibility and emission spectrum balance deteriorate

Engineering Contradiction:
Improvewavelength conversion member structureVSAvoidcolor reproducibility
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The wavelength conversion member is segmented into multiple fluorescent substance layers, each responsible for converting light to specific wavelength regions. This segmentation allows independent optimization of each layer's emission characteristics, enabling precise control over the overall emission spectrum and improving color reproducibility while maintaining manageable device complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses composite fluorescent materials with different emission characteristics stacked in specific arrangements. By combining multiple fluorescent substances with complementary emission spectra, the system achieves balanced red, green, and blue wavelength region emissions, thereby improving color reproducibility without excessively increasing device complexity

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If multiple fluorescent substances are stacked to improve color reproducibility, then the emission spectrum balance improves, but the device complexity increases

Engineering Contradiction:
Improveemission spectrum balanceVSAvoidwavelength conversion member structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent transitions from a single-layer to a multi-layer stacked structure, adding the vertical dimension to the wavelength conversion member design. This dimensional change enables sophisticated spectral control through layered fluorescent substances while maintaining a compact overall structure, thus improving emission spectrum balance without proportionally increasing device complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Duration of action of stationary object

If fluorescent substances are used for wavelength conversion, then the lifetime is improved compared to mercury lamps, but the emission spectrum balance and color reproducibility deteriorate

Engineering Contradiction:
Improvelight source lifetimeVSAvoidcolor reproducibility
Core Design Contradiction:
Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The patent employs composite fluorescent materials with carefully selected emission characteristics that complement each other. By stacking fluorescent substances that emit in different wavelength regions (red, green, blue), the system achieves balanced color reproduction while maintaining the long lifetime advantage of solid-state fluorescent materials

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

The solution enables a high-efficiency light source with improved color reproducibility, capable of producing standard colors and white light by optimizing the emission spectra of red, green, and blue components.

Implementation Method 1

a first fluorescent substance, and a second fluorescent substance, wherein the first fluorescent substance is excited by light in a first wavelength region to emit light in a second wavelength region

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 2

the second fluorescent substance is excited by light in the first wavelength region and light in the second wavelength region to emit light in a third wavelength region

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentEP3467584B1Light source device and projection display device
Publication Date: 2021.12.22 SONY GROUP CORP
  • EP3467584B1 patent drawingFigure 1
  • EP3467584B1 patent drawingFigure 2
  • EP3467584B1 patent drawingFigure 3~4

AI summary

[Object] To implement a light source apparatus that is high in efficiency and has favorable color reproducibility. [Solution] There is provided a light source apparatus including: a light source configured to output light in a first wavelength region; and a wavelength conversion member including a first fluorescent substance and a second fluorescent substance, the first fluorescent substance being excited by the light in the first wavelength region to emit light in a second wavelength region, the second fluorescent substance being stacked on the first fluorescent substance and excited by the light in the first wavelength region and the light in the second wavelength region to emit light in a third wavelength region.