Laser Light Source Unit With Diffusion Layer for Safety
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Solution Overview
Problem
Conventional light source units using light emitting diodes face inefficiencies due to high Etendue values, leading to reduced light utilization and safety concerns with coherent laser diode outputs, particularly when fluorescent materials are dislodged, potentially causing direct emission of high-intensity light outside the projector.
Innovation Solution
A light source unit incorporating a light emitting wheel with a diffusion layer on a circular substrate, where laser light is converted into incoherent light by minute irregularities, preventing coherent light emission and enhancing light distribution, thereby ensuring safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser diode is used as a light source to achieve high output, then the light output intensity is improved, but the safety is worsened due to the risk of coherent light emission outside the projector when fluorescent materials are dislodged
Solution Approach 1:
A diffusion layer is introduced as an intermediary component between the laser diode and the external environment. This diffusion layer converts the coherent laser light into incoherent diffused light, preventing direct emission of harmful coherent light while maintaining the high output intensity benefit of the laser diode.
Solution Approach 2:
The coherence parameter of the light is changed by introducing the diffusion layer. The laser light with high coherence is transformed into diffused light with low coherence, fundamentally altering the light's properties to eliminate the safety hazard while preserving the intensity advantage.
2Illumination intensity
If multiple light emitting diodes are used to increase output, then the light output is improved, but the light utilization efficiency is worsened due to high Etendue value causing light scattering
Solution Approach 1:
The Etendue parameter is effectively managed by using a single laser diode source with a diffusion layer, rather than multiple LEDs. The diffusion layer controls the angular distribution of light, effectively managing the Etendue to prevent light scattering losses while maintaining high output intensity.
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 solution effectively prevents coherent light from being emitted outside the projector, improving safety and maintaining high light utilization efficiency by diffusing laser light through the light emitting wheel's irregularities, reducing the risk of device failure and ensuring safer operation.
Implementation Method 1
a diffusion layer in at least a light shining area where light from the light source is shone for diffusion of the light so shone
Implementation Method 2
fluorescent materials are disposed at a central point of the spherical housing, whereby light emitted from the light emitting diodes is used as excitation light which causes the fluorescent material to emit light for use
Data Source
AI summary
A projector includes a light source unit, a light guiding device, a display device, a projection side optical system, and a projector control unit. The light source unit includes a light source which emits laser light in the wavelength band of blue, a light emitting wheel disposed on an optical axis of the light source, and a wheel motor for driving to rotate the light emitting wheel. The light emitting wheel is formed of a circular substrate having a diffusion layer on a predetermined surface thereof, the diffusion layer being made up of minute irregularities which are formed directly on a surface of the circular substrate.