Phosphor Member Reflective Layer Chromaticity Adjustment

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Solution Overview

Problem

The hue of light emitted from light source devices changes due to deterioration of the excitation light source and temperature-dependent phosphor conversion efficiency, making it difficult to accurately adjust the chromaticity of the mixed light.

Innovation Solution

A phosphor member with a reflective layer that transmits and reflects mixed color light, allowing for direct monitoring and accurate detection of chromaticity, and a light source device with an optical sensor to measure and adjust the chromaticity based on the measured results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the excitation light source is used for a long period of time, then the light source device can maintain continuous operation, but the amount of excitation light emitted decreases due to deterioration

Engineering Contradiction:

Improvecontinuous operation timeVSAvoidamount of excitation light

Core Design Contradiction:

Duration of action of stationary objectVSIllumination intensity

Solution Approach 1:

The patent implements a feedback mechanism where an optical sensor continuously monitors the chromaticity of the mixed light emitted by the phosphor member. When deterioration of the excitation light source is detected through chromaticity changes, the system automatically adjusts the drive current to the excitation light source to compensate for the reduction in excitation light output, thereby maintaining stable white light output over extended operation periods

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the drive current parameter of the excitation light source based on detected chromaticity variations. By adjusting this electrical parameter in response to phosphor deterioration or light source aging, the system compensates for reduced excitation light output and maintains consistent white light chromaticity throughout the operational lifetime

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the temperature of the phosphor increases, then the phosphor can convert excitation energy more rapidly, but the conversion efficiency of fluorescent light decreases

Engineering Contradiction:

Improveconversion rate of excitation energyVSAvoidconversion efficiency of fluorescent light

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The optical sensor provides real-time feedback on the chromaticity of the emitted light, which reflects the actual conversion efficiency of the phosphor. The control system uses this feedback to adjust the drive current to the excitation light source, compensating for temperature-induced efficiency variations and maintaining optimal energy conversion throughout the phosphor's operational life

Inventive Principle:

Principle #23Feedback

3Loss of energy

If the amount of excitation light irradiated to the phosphor is decreased, then the temperature of the phosphor is decreased and conversion efficiency is increased, but the amount of fluorescent light included in white light is increased due to hue change

Engineering Contradiction:

Improveconversion efficiency of fluorescent lightVSAvoidhue of white light

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The system continuously monitors the chromaticity of the mixed light using an optical sensor and automatically adjusts the drive current to the excitation light source. This feedback control compensates for changes in fluorescent light output caused by temperature variations, maintaining stable white light hue and color temperature throughout operation

Inventive Principle:

Principle #23Feedback

4Measurement precision

If direct monitoring of mixed light is implemented, then accurate detection of chromaticity is achieved, but the device complexity increases

Engineering Contradiction:

Improveaccuracy of chromaticity detectionVSAvoidcomplexity of monitoring system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent incorporates an optical sensor that directly monitors the mixed light from the phosphor member, providing accurate chromaticity detection. This measurement feeds back to a control mechanism that adjusts the excitation light source drive current, creating a closed-loop system that automatically compensates for chromaticity drift without requiring complex external monitoring equipment

Inventive Principle:

Principle #23Feedback

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

Enables accurate detection and adjustment of chromaticity, reducing changes in the hue of the light emitted over time and maintaining consistent color output.

Implementation Method 1

a phosphor plate that converts a portion of excitation light into fluorescent light

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a reflective layer that is provided on the phosphor plate and that transmits a part of the mixed color light and reflects a remaining part of the mixed color light

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11340444B2Phosphor member, light source device, projector and chromaticity adjustment method

Publication Date: 2022.05.24 SHARP NEC DISPLAY SOLUTIONS LTD

AI summary

A phosphor member includes: a phosphor plate that converts a part of excitation light into fluorescent light and emits mixed color light including the fluorescent light and the remaining part of the excitation light; and a reflective layer that is provided on the phosphor plate and that transmits a part of the mixed color light and reflects the remaining part.