Phosphor Wheel Thermal Management in Laser Projectors
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Solution Overview
Problem
Image display apparatuses using solid-state light sources face challenges in maintaining proper operation and preventing deterioration due to temperature fluctuations, as existing technologies do not effectively manage temperature changes, leading to potential component damage and reduced performance.
Innovation Solution
The apparatus includes a light source section with solid-state light sources, an image generation section, a projection section, a housing with an inlet for external air, and sensors to measure external and light source temperatures, with a control section that adjusts the output of the light sources based on temperature readings to ensure proper operation and prevent deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the application amount of laser light to the phosphor wheel is increased to improve the output of the light source apparatus, then the light output is improved, but the heat generation from the phosphor wheel is also increased
Solution Approach 1:
The phosphor wheel is divided into multiple phosphor layers with different materials (first phosphor layer with yellow phosphor, second phosphor layer with red phosphor) that can be independently excited by laser light. This segmentation allows the excitation energy to be distributed across different layers, reducing the heat concentration in any single layer while maintaining overall light output.
Solution Approach 2:
Different phosphor materials are used in different regions/layers of the phosphor wheel, with each phosphor layer optimized for specific wavelength conversion. The first phosphor layer converts blue laser light to yellow light, while the second phosphor layer converts blue laser light to red light, creating local quality variations that improve overall efficiency and reduce heat generation.
2Temperature
If the phosphor wheel rotates at high speed to improve cooling performance, then the cooling performance is improved, but the device complexity and power consumption increase
Solution Approach 1:
The phosphor wheel structure itself serves the dual function of light generation and heat dissipation. By designing the phosphor wheel with multiple layers and appropriate thermal conductivity materials, the wheel naturally conducts heat away from the excitation region during its rotation, reducing the need for additional active cooling mechanisms.
3Ease of manufacture
If the phosphor wheel structure is simplified to reduce manufacturing cost, then the manufacturing cost is reduced, but the heat dissipation performance deteriorates
Solution Approach 1:
The phosphor wheel uses composite material structure combining different phosphor materials (yellow phosphor, red phosphor) with a base material that has appropriate thermal conductivity. This composite structure achieves both the required optical performance for light generation and sufficient thermal conductivity for heat dissipation, without requiring complex manufacturing processes.
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 allows the image display apparatus to maintain optimal performance by adjusting light output in response to temperature changes, thereby preventing component damage and extending the operational life of the apparatus.
Implementation Method 1
Blue laser light that is output from the solid-state light source is applied to a phosphor wheel as excitation light. The phosphor wheel includes a base and a phosphor layer formed thereon. Excitation light is applied to the phosphor layer, and thus yellow fluorescence is emitted.
Implementation Method 2
The blue light and yellow light emitted from the phosphor layer are combined, to output white light
Implementation Method 3
Patent Document 2 describes heat generation of the phosphor wheel due to the application of the laser light. For example, when the application amount to the phosphor wheel is increased so as to improve the output of the light source apparatus, the amount of heat generation from the phosphor wheel is also increased.
Implementation Method 4
cooling performance is improved by using crystalline members excellent in thermal conductivity, such as crystal and sapphire, for the base material of the phosphor wheel
Data Source
AI summary
An image display apparatus includes a laser light source, a light modulator, a first sensor, a second sensor, a third sensor, and circuitry. The light modulator generates an image based on light from the laser light source. The first sensor measures a first temperature in a vicinity of an air inlet of a housing of the image display apparatus. The second sensor measures a second temperature associated with the laser light source. The third sensor measures a third temperature associated with the light modulator. The circuitry is configured to control output of the laser light source based on at least one of the first, second, or third temperatures.