Solid-State White Light Source for Projection Displays
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Solution Overview
Problem
Conventional projection-type display apparatuses using super high-pressure mercury lamps face issues with UV stress on organic materials, short lifespan, brightness degradation, and disposal challenges, while solid-state light sources fail to provide a suitable point-like white light source, leading to deterioration of white-balance and color shading.
Innovation Solution
A projection-type display apparatus utilizing a light source unit that emits white light, separated into red, green, and blue colors, modulated by respective light modulating portions, and composed into a white image using a light composing unit, with an excitation light from a semiconductor laser and emission light from a fluorescent substance, producing a nearly parallel, polarized white light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a super high-pressure mercury lamp is used as the light source, then high brightness and high efficiency are achieved, but UV stress damages organic materials, the lamp has short lifespan, and disposal is difficult
Solution Approach 1:
The patent changes the fundamental parameters of the light source from a discharge lamp (mercury lamp) to a solid-state light source (light emitting diode). This parameter change eliminates UV radiation, extends lifespan, and improves shock resistance while maintaining brightness through optimized optical system design including aspherical lenses and reflectors.
Solution Approach 2:
The patent replaces the mechanical/electrical discharge lamp system with a solid-state light emitting diode system. This substitution eliminates the need for high-voltage power sources, removes UV radiation issues, and provides a more reliable, maintenance-free light source while achieving comparable brightness through efficient light extraction and optical design.
2Reliability
If solid-state light sources are used, then lifespan and shock resistance are improved, but they fail to provide sufficient point-like white light, causing deterioration of white-balance and color shading
Solution Approach 1:
The patent introduces a yellow phosphor layer as an intermediary between the blue light emitting diode and the final white light output. The blue LED excites the yellow phosphor, which converts some blue light to yellow, creating white light. This intermediary approach enables the solid-state light source to produce uniform white light with proper color balance while maintaining the reliability advantages of solid-state technology.
Solution Approach 2:
The patent employs aspherical lenses and curved reflectors to properly direct and uniformize the light from the solid-state source. These curved optical elements compensate for the non-point-like nature of the LED source, ensuring uniform illumination and accurate color distribution across the projection area, thereby achieving manufacturing precision in white-balance and color uniformity.
3Illumination intensity
If discharge lamps are used, then high brightness is achieved, but high-voltage power sources are required, making handling difficult
Solution Approach 1:
The patent replaces the high-voltage discharge lamp system with a low-voltage solid-state light emitting diode system. This substitution eliminates the need for high-voltage power sources, making the device safer and easier to handle while maintaining brightness through efficient optical design including aspherical lenses and optimized reflector geometry.
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 solution enables sufficient performance in optical parts, preventing deterioration of white-balance and color shading, with a long-lasting, shock-resistant, and environmentally friendly solid-state light source, eliminating the need for high-voltage power sources.
Implementation Method 1
a light emitting diode for generating a light of blue (B) color... being excited by absorbing the B-light, thereby generating the G-light
Implementation Method 2
applying a light emitting diode for generating a light of blue (B) color, in the place of the light emitting diode for generating a light with using the UV rays
Data Source
AI summary
A projection-type display apparatus, being suitable to be applied as a light source of a solid-state light source, in the place of a conventional lamp, comprises: a light source unit, which is configured to emit a white-color light therefrom; a light separation optic system, which is configured to separate the white color light from the light source unit into three primary color lights, red-color (R), green-color (G) and blue-color (B); R, G and B light modulating portions, each of which modulates each of R, G and B polarized lights separated, depending on a video signal, respectively; a light composing unit, which is configured to compose optical images, which are formed by the R, G and B light modulating portions; and a projecting portion, which is configure to project the optical image composed, enlargedly, wherein the light source unit emits a white color light emitting from a nearly point-like light source, including an excitation light from a solid-state light emitting element therein.