Hybrid Lighting Device for Projection Displays
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Solution Overview
Problem
Current projection-type display devices face challenges in achieving both compactness and high luminance due to limitations in light source size and etendue constraints, particularly with the use of fluorescent light sources and LEDs, where high-luminance green components are not mass-produced, and the area and divergence of LEDs are limited by etendue, restricting brightness improvement.
Innovation Solution
A lighting device incorporating an excitation light source, a phosphor unit, collimator lenses, solid-state light sources (red and blue lasers), and a dichroic mirror with color-combining means to combine and condense light, allowing for increased luminance and compactness by using hybrid light sources that combine solid-state light sources with phosphor-based green light, optimizing excitation light intensity and reducing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluorescent light sources are used to achieve high luminance, then the luminance is improved, but the device size increases
Solution Approach 1:
The patent combines solid-state light sources (lasers or LEDs) with phosphor-based green light sources into a hybrid lighting device. The solid-state light sources provide red and blue light, while the phosphor layer converts ultraviolet or blue light to green light. This merging of different light generation mechanisms allows the device to achieve high luminance across all three primary colors without requiring large fluorescent light sources for each color channel.
Solution Approach 2:
The patent uses composite light generation approaches by combining inorganic phosphor materials with solid-state light sources. The phosphor layer acts as a composite material that converts light from the solid-state sources into the desired green spectrum, creating a hybrid system that leverages the compactness of solid-state devices while achieving the high luminance of fluorescent sources.
2Volume of moving object
If LEDs are used to reduce device size, then the device size is reduced, but the luminance is limited by etendue constraints
Solution Approach 1:
The patent merges LED or laser light sources with phosphor conversion layers to create a hybrid system. This combination allows the device to maintain the compact form factor of solid-state sources while achieving higher luminance through the phosphor's ability to convert light efficiently across broad spectral ranges, thereby overcoming the etendue limitations of pure LED systems.
Solution Approach 2:
The patent changes the operational parameters of the light source system by using phosphor materials with specific emission characteristics and optimizing the excitation wavelength. This allows the system to achieve higher luminance output from compact solid-state sources by transforming the light parameters through phosphor conversion, effectively bypassing the luminance limits of direct LED emission.
3Illumination intensity
If green lasers or green LEDs are mass-produced to achieve high luminance, then the luminance is improved, but the manufacturing complexity increases due to limited availability of high-luminance green components
Solution Approach 1:
The patent introduces phosphor materials as intermediary substances that convert light from readily available solid-state sources (ultraviolet or blue LEDs, red and blue lasers) into green light. This intermediary approach allows the system to achieve high green luminance without requiring mass-produced green laser or green LED components, thereby avoiding the manufacturing complexity and availability issues associated with high-luminance green light sources.
Solution Approach 2:
The patent employs phosphor materials that can be easily manufactured and integrated into the device as a replaceable component. Rather than relying on expensive and difficult-to-manufacture high-luminance green lasers or LEDs, the system uses cost-effective phosphor layers that can be applied as coatings or embedded in the light path, simplifying the manufacturing process and improving component availability.
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 enables a compact and high-luminance lighting device that overcomes the size limitations of traditional phosphor-based light sources and etendue constraints, enhancing the luminance of green fluorescent light through improved excitation light intensity and eliminating the need for costly polarization conversion elements, resulting in a more efficient and cost-effective projection-type display device.
Implementation Method 1
a phosphor unit that emits fluorescent light by excitation caused by excitation light supplied from the excitation light source unit
Implementation Method 2
a collimator lens that converts the fluorescent light emitted from the phosphor unit to parallel luminous flux
Implementation Method 3
a dichroic mirror in which the excitation light supplied from the excitation light source unit and light supplied from the first solid-state light source are combined and exited as a combined light; the dichroic mirror has a property of transmitting the excitation light and reflecting the first light
Implementation Method 4
color-combining means that is provided with first to fourth surfaces, light that was combined by the dichroic mirror being supplied to the first surface, and form the combined light supplied to the first surface, the excitation light being exited toward the phosphor unit from the second surface, the first light being exited from the fourth surface, the fluorescent light emitted from the phosphor unit being supplied to the second surface, the fluorescent light that was supplied to the second surface being exited from the fourth surface, the second light that was supplied from the second solid-state light source being supplied to the third surface, and the second light that was supplied to the third surface being exited from the fourth surface
Data Source
AI summary
A lighting device includes excitation light sources, phosphor wheel that emits green fluorescent light, a collimator lens that converts the emitted fluorescent light into parallel luminous flux, a red laser, a blue laser, a dichroic mirror that combines the excitation light supplied from the excitation light sources and the light supplied from the red laser, and a cross dichroic prism that combines the fluorescent light emitted from phosphor wheel, the light supplied from the red laser and the light supplied from the blue laser. The cross dichroic prism supplies the excitation light supplied from the excitation light sources to the collimator lens and the collimator lens condenses the incident excitation light on the phosphor wheel.