Light Source Unit Segmented Luminous Wheel for Projector Luminance
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Solution Overview
Problem
Conventional light source units for projectors, particularly those using luminescent materials, face issues with insufficient red luminescence due to lower light emitting efficiency compared to green and blue wavelengths, resulting in reduced screen luminance.
Innovation Solution
A light source unit incorporating a luminous wheel with segment areas for reflecting and transmitting light, utilizing a primary light source emitting blue light to excite a luminescent material layer for green luminescence and a secondary light source emitting red light, with a collective optical system to converge these lights into a single optical path, and a light source control mechanism to manage their emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a luminescent material layer is used to convert ultraviolet light into visible light for red, green and blue wavelength bands, then color image projection is enabled, but the luminance of red becomes insufficient due to lower luminous efficiency of red luminescent material
Solution Approach 1:
The luminous wheel is divided into multiple segment areas (first segment area with luminescent material layer, second segment area without luminescent material layer). This segmentation allows different optical functions in different segments, enabling the system to switch between luminescence conversion and direct light transmission based on the segment position, thereby compensating for the low luminous efficiency of red luminescent material.
Solution Approach 2:
The luminous wheel rotates periodically to bring different segment areas into the light path. This periodic action allows the system to alternately use the luminescent material layer for color conversion and the non-luminescent segment for direct light transmission, optimizing the overall luminance output particularly for the red wavelength band where luminescent efficiency is low.
2Illumination intensity
If multiple light sources emitting at different wavelengths are employed to increase excitation energy, then the luminance of screen can be improved, but the device complexity increases
Solution Approach 1:
The single light source is designed to serve multiple functions: it acts as an excitation light source for the luminescent material layer in the first segment area, and as a direct illumination source through the second segment area without luminescent material. This multi-functionality eliminates the need for separate light sources for different wavelength bands, reducing device complexity while maintaining high screen luminance.
Solution Approach 2:
The system changes the optical parameters (wavelength, intensity) of the light by utilizing the luminescent material's wavelength conversion property. The single light source emits ultraviolet light that is converted to visible light of different wavelength bands by the luminescent material, effectively achieving multi-wavelength illumination without multiple light sources.
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 enhances screen luminance by effectively utilizing luminescent materials with high efficiency for green and red wavelengths, improving color purity and overall brightness in projector images.
Implementation Method 1
a luminescent material layer which receives ultraviolet light as excitation light emitted from a solid-state light source and converts the ultraviolet light so received into visible light
Implementation Method 2
at least one of the plurality of segment areas is made into a reflecting portion, a luminescent material layer is formed on the reflecting area which emits light of a predetermined wavelength band by receiving excitation light
Data Source
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AI summary
To provide a light source unit (63) which can increase luminance and a projector (10) including this light source unit. This light source unit includes a luminous wheel (71) having a segment area (1) on which a luminescent material layer (131) is formed which emits light of a predetermined wavelength band by receiving light, and a segment area (2) which is made into a transmission portion (141) which transmits light, a primary light source (72) which shines light of a visible wavelength band on to the luminous wheel (71), a secondary light source (82) which emits light of a wavelength band which is different from light from the luminescent material layer (131) and light from the primary light source (72), a collective optical system (151) which collects light from the luminous wheel (71) and the secondary light source (82) to cause them to converge to the same optical path, and a light source control device (41) which controls the emission of light from the light sources (72,82).