Light Source Device Fluorescence Management
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Solution Overview
Problem
In existing light source devices for projectors, the contact between the rod lens and phosphor sheet leads to a decrease in light use efficiency due to fluorescence being emitted outside, resulting in inefficient light utilization.
Innovation Solution
A light source device configuration that includes a light source section, a first optical element, a second optical element with a specific plane of incidence and exit surface, and a wavelength conversion element, where the second optical element and wavelength conversion element are positioned with their exit surface and incidence plane opposed at a distance, and the wavelength conversion element has a larger incidence plane than exit surface, preventing fluorescence from being guided back into the light guide and enhancing light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rod lens and phosphor sheet are in contact, then the structure is simple and easy to manufacture, but the fluorescence generated in the phosphor sheet is guided toward the rod lens and emitted outside, decreasing light use efficiency
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the rod lens and phosphor sheet. This resin layer with refractive index of 1.4-1.6 prevents total internal reflection at the interface, stopping fluorescence from being guided back into the rod lens while maintaining close proximity for effective light transfer. This resolves the contradiction by preserving structural simplicity while eliminating energy loss through fluorescence guidance.
Solution Approach 2:
The refractive index parameter of the medium between rod lens and phosphor sheet is changed from air (or contact interface) to resin with refractive index of 1.4-1.6. This parameter change modifies the optical conditions at the interface, preventing total internal reflection of fluorescence while maintaining structural simplicity and manufacturing ease.
2Length of moving object
If the rod lens and phosphor sheet are in contact, then the light path is short and compact, but heat is transferred to the light guide causing reliability issues
Solution Approach 1:
The resin layer serves as a thermal isolation intermediary between the phosphor sheet (heat source) and rod lens (light guide). This thin layer with low thermal conductivity prevents heat transfer to the light guide while maintaining optical proximity, thus preserving compact light path length while improving light guide reliability through thermal isolation.
Solution Approach 2:
The thermal interaction between phosphor sheet and light guide is extracted/separated by introducing the resin layer. This allows the optical function to remain efficient (short light path) while the thermal function is isolated, preventing heat transfer and improving reliability without increasing overall structure size.
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 improves light use efficiency by preventing fluorescence from being emitted back into the light guide, reducing heat transfer, and maintaining the reliability of the light guide, resulting in a brighter image display.
Implementation Method 1
a first optical element configured to collect the first light emitted from the light source section
Implementation Method 2
a second optical element having a first plane of incidence which the first light collected by the first optical element enters, and a first exit surface different from the first plane of incidence, and configured to guide the first light entering the second optical element through the first plane of incidence to emit the first light from the first exit surface
Implementation Method 3
a wavelength conversion element having a second plane of incidence which the first light emitted from the first exit surface of the second optical element enters, and a second exit surface different from the second plane of incidence, and configured to convert the first light entering the wavelength conversion element through the second plane of incidence into second light having a second wavelength band different from the first wavelength band
Implementation Method 4
a first substrate configured to hold the wavelength conversion element and thermally coupled to the wavelength conversion element
Implementation Method 5
the wavelength conversion element may have a first film which is disposed on the second plane of incidence, transmits the first light, and reflects the second light
Data Source
AI summary
Alight source device according to the present disclosure includes a light source section configured to emit first light in a first wavelength band, a first optical element configured to collect the first light emitted from the light source section, a second optical element having a first plane of incidence and a first exit surface, and a wavelength conversion element having a second plane of incidence and a second exit surface, and configured to convert the first light entering the wavelength conversion element through the second plane of incidence into second light having a second wavelength band, wherein the second optical element and the wavelength conversion element are disposed in a state in which the first exit surface and the second plane of incidence are opposed to each other at a distance from each other, and the second plane of incidence is larger in size than the first exit surface.