Rotatable Wavelength Conversion Element for Projector Light Source
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Solution Overview
Problem
Current solid-state light sources for projectors have a limited color gamut and efficiency due to the red light component being a rate-limiting factor, leading to wasted green light and reduced luminance, especially when using Ce-YAG phosphors and filters.
Innovation Solution
A light source unit with a phosphor layer and a quantum-dot layer disposed in order relative to the light source section on a rotatable substrate, where the exciting light first enters the phosphor layer, reducing Stokes loss and suppressing temperature increase in the quantum-dot layer, thereby enhancing luminance and color gamut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If exciting light directly enters the quantum-dot layer, then the quantum-dot layer can be efficiently excited, but Stokes loss increases and temperature rises causing emission wavelength instability
Solution Approach 1:
The patent introduces a phosphor layer as an intermediary between the light source and quantum-dot layer. The phosphor layer first converts the light source emission to fluorescence, which then excites the quantum-dot layer. This intermediary conversion reduces Stokes loss and suppresses temperature increase in the quantum-dot layer, stabilizing emission wavelength while maintaining excitation efficiency.
2Device complexity
If a Ce-YAG phosphor with filter is used to derive red and green light, then the light source can be simplified, but the color gamut becomes narrow and green light efficiency decreases
Solution Approach 1:
The patent uses a composite wavelength conversion system combining Ce-YAG phosphor particles and quantum dots on a single rotatable wheel. The Ce-YAG phosphor converts blue light to yellow-green, while quantum dots convert blue light to red, eliminating the need for separate filters and enabling broader color gamut with improved green light utilization efficiency.
3Device complexity
If the phosphor layer and quantum-dot layer are disposed in parallel, then the structure is simplified, but the emission output and wavelength stability deteriorate
Solution Approach 1:
The patent transitions from a parallel layer structure to a sequential stacked structure where the phosphor layer and quantum-dot layer are arranged in the light path sequence. This dimensional reorganization allows the phosphor layer's fluorescence to serve as excitation source for the quantum-dot layer, improving emission wavelength stability while maintaining structural simplicity through the rotatable wheel design.
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 achieves higher luminance and a wider color gamut by optimizing the emission output and wavelength of the light source, improving efficiency and reducing color changes, while also extending the lifetime of the quantum dots.
Implementation Method 1
the quantum-dot layer is excited mainly by fluorescence, resulting in reduction in Stokes loss, and suppression of an increase in temperature of the quantum-dot layer
Implementation Method 2
the quantum-dot layer including the plurality of quantum dots are disposed in this order relative to the light source section
Data Source
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AI summary
A light source unit according to an embodiment of the present disclosure includes: a light source section; and a wavelength conversion element that is excited by exciting light from the light source section to emit fluorescent light. The wavelength conversion element includes a substrate that is rotatable around a rotation axis, a phosphor layer including a plurality of phosphor particles, and a quantum-dot layer including a plurality of quantum dots. The phosphor layer and the quantum-dot layer are disposed in this order relative to the light source section.