Wavelength Conversion Element Thermal Stress Management
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Solution Overview
Problem
Existing wavelength conversion elements in light source devices for projectors face issues with thermal stress and peeling due to differences in linear expansion coefficients between the fluorescent body layer, heat dissipation layer, and holding member, leading to inefficient heat dissipation and potential mechanical failure.
Innovation Solution
A wavelength conversion element is designed with a configuration that includes a wavelength conversion layer, a first substrate with a lower linear expansion coefficient and higher thermal conductivity than the wavelength conversion layer, and a second substrate with an even higher thermal conductivity, along with bonding layers to manage thermal stress and expansion differences, ensuring efficient heat dissipation and preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a light transmissive heat dissipation layer is added between the fluorescent body layer and heat dissipation member, then heat dissipation is improved, but thermal stress and peeling occur due to differences in linear expansion coefficients among members
Solution Approach 1:
A first bonding layer is introduced between the wavelength conversion layer and first substrate, and a second bonding layer between the first substrate and second substrate. These intermediary bonding layers act as stress buffer zones that accommodate thermal expansion differences, preventing direct stress transmission that would cause peeling while maintaining thermal conduction pathways for heat dissipation.
Solution Approach 2:
The patent specifies that the linear expansion coefficient of the first substrate is smaller than that of the wavelength conversion layer, and the linear expansion coefficient of the wavelength conversion layer is smaller than that of the second substrate. This graded parameter arrangement creates a progressive transition zone that reduces thermal stress concentration at interfaces, preventing peeling while enabling effective heat dissipation.
2Temperature
If the fluorescent body and holding member are bonded by chemical bond without intermediate members, then thermal conductivity is increased, but heat dissipation remains insufficient and thermal stress causes peeling
Solution Approach 1:
The heat dissipation path is segmented into multiple stages: wavelength conversion layer to first substrate (via first bonding layer), and first substrate to second substrate (via second bonding layer). This segmentation allows each interface to be optimized independently - the first substrate provides high thermal conductivity bonding, while the second substrate provides structural support and additional heat sinking, with bonding layers preventing stress-induced peeling.
3Ease of manufacture
If members are heated during manufacturing process, then bonding is achieved, but thermal stress generates peeling due to linear expansion coefficient differences
Solution Approach 1:
The bonding layers are specifically designed to accommodate and cushion the thermal stress that will be generated during the heating process. By selecting materials with appropriate linear expansion coefficients and bonding characteristics, the structure is pre-configured to absorb expansion stresses without causing peeling, ensuring reliability is maintained despite the necessary thermal processing for bonding.
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 configuration effectively dissipates heat generated in the wavelength conversion layer, preventing peeling and ensuring the reliability of the light source device and projector by minimizing thermal stress through strategic layer thickness and material properties.
Implementation Method 1
A wavelength conversion element according to an aspect of the present disclosure includes: a wavelength conversion layer configured to convert light in a first wavelength band into light in a second wavelength band different from the first wavelength band
Implementation Method 2
A thermal conductivity of the first substrate is larger than a thermal conductivity of the wavelength conversion layer. A thermal conductivity of the second substrate is larger than the thermal conductivity of the wavelength conversion layer
Data Source
AI summary
A wavelength conversion element according to the present disclosure includes: a wavelength conversion layer; a first substrate; a second substrate; a first intermediate layer; and a second intermediate layer. A linear expansion coefficient of the first substrate is smaller than a linear expansion coefficient of the wavelength conversion layer. The linear expansion coefficient of the wavelength conversion layer is smaller than a linear expansion coefficient of the second substrate. The linear expansion coefficient of the first substrate is smaller than the linear expansion coefficient of the second substrate. A thermal conductivity of the first substrate is larger than a thermal conductivity of the wavelength conversion layer. A thermal conductivity of the second substrate is larger than the thermal conductivity of the wavelength conversion layer.