Projection System Dichroic Filter Chromaticity Control

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Solution Overview

Problem

Projection systems with a yellow phosphor wheel face challenges in achieving the required intensity, chromaticity, and white balance according to the DCI standard, as they produce inhomogeneous red and green light, necessitating additional device elements that reduce overall intensity and risk overheating the light source.

Innovation Solution

A projection system comprising a first and second light source, a wavelength converter, and light splitting elements that adjust the light paths and intensities to achieve the desired chromaticity and white balance with a lower power output, using a dichroic second light splitting element with a half transmission wavelength between the peak intensity wavelengths of the first and third light, and a notch filter to optimize the intensity ratio of red, green, and blue light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If additional device elements are added to reduce red or green light, then chromaticity and white balance are improved, but overall intensity is reduced

Engineering Contradiction:

Improvechromaticity and white balanceVSAvoidoverall intensity

Core Design Contradiction:

Manufacturing precisionVSIllumination intensity

Solution Approach 1:

The patent extracts and removes specific wavelength ranges (red and green light) from the phosphor wheel output using wavelength-selective filters, then replaces them with targeted laser light sources. This extraction approach allows precise control over chromaticity while avoiding the intensity loss associated with broad-band filtering, as only the necessary spectral components are removed and replaced efficiently.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the spectral parameters by replacing the broad-band phosphor output with narrow-band laser light sources at specific wavelengths. This parameter change enables precise control over the spectral composition to achieve DCI standard chromaticity while maintaining higher overall intensity through efficient laser conversion rather than lossy filtering.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If power output of light source is raised to meet required intensity, then intensity is improved, but risk of over-heating and reduction in life span increase

Engineering Contradiction:

ImproveintensityVSAvoidrisk of over-heating and reduction in life span

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent changes the light source from broad-band phosphor to narrow-band laser sources operating at lower power levels. This parameter change in the spectral characteristics allows the system to achieve required intensity with reduced power consumption, thereby lowering the risk of overheating and extending light source life span while maintaining DCI standard compliance.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If yellow phosphor wheel is used, then system complexity is reduced, but difficulty in achieving required chromaticity and white balance increases

Engineering Contradiction:

Improvesystem complexityVSAvoidchromaticity and white balance

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent segments the light generation system into separate functional components: laser light sources for precise chromaticity control and a phosphor wheel for broad-spectrum generation. This segmentation allows each component to be optimized independently - the lasers handle the precision chromaticity requirements while the phosphor wheel provides the necessary spectral coverage, achieving DCI standards without excessive overall system complexity.

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

The system effectively achieves DCI standards with reduced power output, minimizing the risk of thermal quench and enhancing operational efficiency while being compatible with prior art systems at a lower cost.

Implementation Method 1

The wavelength converter is configured to convert a portion or all of the second light into a third light, in which the third light includes a green light and a red light

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

The second light splitting element is configured to remove a portion of the red light of the third light

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

The first light splitting element is configured to permit the first light to pass through or to be reflected

Methodology Applied

Scientific EffectWavelength-selective reflection and transmission: Dichroic Filter

Data Source

PatentUS10571791B2Projection system and optimizing method thereof

Publication Date: 2020.02.25 DELTA ELECTRONICS INC(CN)

AI summary

A projection system is provided, which includes a first light source, a second light source, a wavelength converter, a first light splitting element, and a second light splitting element. The first light source is configured to emit a first light. The second light source is configured to emit a second light. The wavelength converter is configured to convert portions or all of the second light into a third light. The third light includes a red light and a green light. A wavelength range of the first light is within a wavelength range of the red light. The first light splitting element is configured to permit the first light to pass through or to be reflected. The second light splitting element is configured for removing a portion of the first light or not removing the first light.