Single Source Illumination Device with Rotating Dichroic Filters

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Solution Overview

Problem

Existing projector systems with phosphor wheels have complex constructions due to the need for multiple phosphor segments for RGB light generation, increasing costs and complexity.

Innovation Solution

A simplified illumination device using a single solid-state light source with a wavelength converter and a light-transmitting control wheel to generate RGB light by rotating dichroic filters, allowing for sequential emission of green, red, and blue light, reducing the number of light sources and phosphor segments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a phosphor wheel with multiple phosphor segments (RGB) is used to generate multiple colors from one light source, then the number of light sources can be reduced, but the device complexity increases due to the segmented phosphor structure

Engineering Contradiction:
Improvenumber of light sourcesVSAvoidphosphor wheel structure
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent divides the wavelength converter into multiple independent converters, each associated with a specific color channel (R, G, B). Each wavelength converter contains phosphor particles that convert the broadband blue light from the solid-state light source to the corresponding color wavelength, eliminating the need for a complex segmented phosphor wheel while achieving the same color generation function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the wavelength conversion function from a single complex phosphor wheel and distributes it across multiple independent wavelength converters. This extraction allows each converter to be optimized for its specific color channel and simplifies the overall structure by removing the rotating mechanism and segmented design.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of manufacture

If a single solid-state light source with multiple phosphor segments is used, then cost can be reduced, but manufacturing complexity increases

Engineering Contradiction:
ImprovecostVSAvoidphosphor segmentation
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent segments the wavelength conversion function into multiple independent converters, each handling a specific color channel. This segmentation allows for simplified manufacturing of each individual converter using standard phosphor coating techniques, avoiding the complex assembly required for segmented phosphor wheels while maintaining cost-effectiveness through the use of a single solid-state light source.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a single solid-state light source that serves multiple functions by illuminating multiple wavelength converters simultaneously. This universal light source approach reduces the total number of light sources needed while the modular wavelength converter design keeps manufacturing simple and cost-effective.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Illumination intensity

If multiple wavelength converters are used with a single light source, then color generation quality can be maintained, but the illumination system becomes more complex

Engineering Contradiction:
Improvecolor generation qualityVSAvoidillumination system
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent divides the illumination system into multiple independent wavelength conversion channels, each with its own converter optimized for a specific color. This segmentation allows each converter to be tuned for optimal color quality in its respective channel while the overall system remains manageable through the use of a single solid-state light source and simple optical distribution.

Inventive Principle:
Principle #1Segmentation

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 solution reduces the complexity and cost of the projector system while maintaining high-quality color generation, allowing for efficient and flexible color tone control.

Implementation Method 1

a wavelength converter including phosphor particles which convert the broadband blue light from the solid-state light source to a wavelength having a color tone different from blue

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a first dichroic mirror which reflects blue light and transmits red light; a second dichroic mirror which transmits blue light and reflects green light

Methodology Applied
Scientific EffectDichroic reflection: Dichroic Filter

Data Source

PatentEP2898368B1Illumination device, projector, and illumination method
Publication Date: 2017.11.08 RICOH CO LTD
  • EP2898368B1 patent drawingFigure 1
  • EP2898368B1 patent drawingFigure 2A
  • EP2898368B1 patent drawingFigure 2B

AI summary

An illumination device(4) includes an excitation light source(10) which emits excitation light, a wavelength converter(14) which generates fluorescent light having a wavelength different from that of the excitation light through the excitation of the excitation light and a light path-splitting member(15) including a first filter and a second filter arranged to alternately come across a light path of the excitation light, wherein the first filter reflects one of the excitation light and the fluorescent light and transmits the other of the excitation light and the fluorescent light, the second filter transmits light reflected by the first filter and reflects light transmitted through the first filter, and the wavelength converter(14) is disposed in a reflection light path or a transmission light path of the excitation light.