Rotating Phosphor Wheel Cooling Fin Thermal Coupling

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Solution Overview

Problem

Existing light source devices for projectors face challenges in maintaining high wavelength conversion efficiency and luminance due to heat management issues, leading to increased device size and weight, as larger radiator fins are required for cooling, which in turn necessitate larger drive sources.

Innovation Solution

A wavelength conversion device with a rotary drive section, a thermally conductive wheel substrate, a phosphor layer, and a cooling fin unit featuring radiator fins and a coupling part that thermally couples the wheel substrate to the base part, allowing efficient heat transfer and airflow for cooling, thereby preventing the need for oversized radiator fins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the output of excitation light is increased to generate higher luminance illumination light, then the luminance of illumination light is improved, but the wavelength conversion efficiency of the phosphor layer decreases due to temperature rise

Engineering Contradiction:

Improveluminance of illumination lightVSAvoidwavelength conversion efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The phosphor wheel is rotated at high speed (e.g., 30,000 rpm or higher) to dynamically cool the phosphor layer during operation. This rotational motion enables continuous heat dissipation from the phosphor layer to the wheel substrate, maintaining wavelength conversion efficiency even when high-power excitation light is applied to achieve high luminance illumination light.

Inventive Principle:

Principle #15Dynamics

2Temperature

If radiator fins are grown in size to enhance cooling performance of the phosphor layer, then the cooling performance is improved, but the weight of radiator fins increases requiring a larger drive source

Engineering Contradiction:

Improvecooling performance of phosphor layerVSAvoidweight of radiator fins

Core Design Contradiction:

TemperatureVSWeight of moving object

Solution Approach 1:

Instead of using large, heavy stationary radiator fins, the invention employs a compact phosphor wheel that rotates at high speed. The rotation itself generates cooling effects through centrifugal force and enhanced heat transfer to the wheel substrate, achieving effective cooling with minimal fin size and weight.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The rotating phosphor wheel creates airflow patterns and centrifugal forces that enhance convective heat transfer from the phosphor layer to the surrounding environment and to the wheel substrate, replacing the need for large passive radiator fins.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Temperature

If a space is formed between the wheel substrate and base part for heat propagation, then heat release capability is improved, but thermal coupling efficiency decreases

Engineering Contradiction:

Improveheat release capabilityVSAvoidthermal coupling efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The phosphor wheel rotates within the space between the wheel substrate and base part, dynamically interacting with the cooling fin unit. This rotation enables continuous heat dissipation through centrifugal force and enhanced convective heat transfer, compensating for the thermal insulation effect of the space while maintaining effective heat release capability.

Inventive Principle:

Principle #15Dynamics

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 cooling performance without increasing the size of the radiator fins, maintaining high wavelength conversion efficiency and luminance while reducing the device's weight and size, and allowing for efficient heat dissipation.

Implementation Method 1

a wheel substrate having thermal conductivity and rotated around a central axis by the rotary drive section

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a plurality of radiator fins disposed at an opposite side to the wheel substrate side of the base part

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

radiator fins disposed at an inner side of a forming area of the phosphor on a reverse surface opposite to an obverse surface of the wheel substrate provided with the phosphor layer

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 4

irradiating a phosphor layer with excitation light emitted from a laser source, and using fluorescence obtained by wavelength conversion in the phosphor layer as illumination light

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS11988950B2Wavelength conversion device, light source device, and projector

Publication Date: 2024.05.21 SEIKO EPSON CORP

AI summary

A wavelength conversion device according to the present disclosure includes a wheel substrate, a phosphor layer formed on the wheel substrate, and a cooling fin unit disposed on the wheel substrate. The cooling fin unit has a base part to be bonded to the wheel substrate. A surface of the wheel substrate includes a first area corresponding to the phosphor layer, and a second area located closer to the central axis than the first area, the surface of the wheel substrate and a surface at the wheel substrate side of the base part are separated from each other to form a space between the wheel substrate and the base part, and a coupling part configured to thermally couple the surface of the wheel substrate and the surface at the wheel substrate side of the base part is disposed in at least the second area of the second surface.