Light Source Optical System Uniform Fluorescent Body Illumination
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Solution Overview
Problem
The increase in light density on a fluorescent body due to higher incident light strength leads to luminance saturation, reducing light conversion efficiency and preventing proportional brightness increases in projector systems, despite using multiple high-output laser diodes.
Innovation Solution
A light source optical system with a micro lens array, dichroic mirror, and condenser lens unit is configured to guide light fluxes from laser diodes to a wavelength conversion element, ensuring uniform light distribution on the fluorescent body while minimizing the size of the dichroic mirror to reduce blue light attenuation, thus maintaining light conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the output of laser diodes is increased to increase projector brightness, then the brightness can be increased, but the light density on the fluorescent body increases causing luminance saturation and reducing light conversion efficiency
Solution Approach 1:
The patent divides the light flux from laser diodes into multiple separate light fluxes using a micro lens array, which segments the concentrated light into distributed light paths. This segmentation allows the light to be uniformly distributed across the fluorescent body surface, preventing local light density saturation while maintaining overall high brightness output, thus resolving the contradiction between brightness and light conversion efficiency
Solution Approach 2:
The patent applies local quality by creating different light distribution characteristics in different regions of the fluorescent body. Through the optical system design including the micro lens array and condenser lens unit, the light flux is distributed such that each local area receives appropriate light intensity, avoiding the luminance saturation that occurs when uniform high intensity is applied across the entire surface
2Loss of energy
If two fly-eye lenses are provided to uniformize light density and suppress high light density areas, then light conversion efficiency is maintained, but the apparatus size increases due to additional optical components
Solution Approach 1:
The patent merges the functions of light flux segmentation and condensation into a integrated optical system where the micro lens array and condenser lens unit work together as a unified configuration. This merging achieves uniform light distribution and maintains light conversion efficiency without requiring separate fly-eye lenses, thereby reducing apparatus size and optical component count while maintaining the desired light uniformization effect
3Adaptability or versatility
If a separate blue light guiding LD and optical system are added to guide blue light to the color separating and combining system, then complete color coverage is achieved, but the entire apparatus size increases
Solution Approach 1:
The patent applies universality by designing the optical system to handle multiple wavelength components (including blue light) through the same optical path and components. The micro lens array and condenser lens unit process both the excitation light for the fluorescent body and the blue light for color separation, eliminating the need for separate blue light guiding LDs and optical systems, thus achieving complete color coverage while minimizing apparatus 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 suppresses the reduction in light conversion efficiency and allows for a smaller light source optical system, maintaining brightness while reducing the apparatus size and minimizing light loss.
Implementation Method 1
a micro lens array 63... divides light fluxes from the laser diodes into a plurality of light fluxes and guides the divided light fluxes
Implementation Method 2
a condenser lens unit 8... condenses light fluxes from the micro lens array 63 onto the fluorescent body 9
Implementation Method 3
irradiates a fluorescent body with a light flux emitted from high output laser diodes (hereinafter referred to as LDs) as an excitation light, and includes a wavelength-converted fluorescent light as a light source light
Implementation Method 4
an LD for guiding a blue color light to a color separating and combining system
Data Source
AI summary
A light source optical system includes a micro lens array, a condenser lens unit, and a dichroic surface. In a direction orthogonal to an optical axis in a cross section parallel to a normal of the dichroic surface and the optical axis of the condenser lens unit, a width of the dichroic surface is narrower than a width of the condenser lens unit. A light source optical system satisfies a predetermined conditional expression.