Phosphor Wheel Yellow Phosphor Red Filter Brightness
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Solution Overview
Problem
Conventional phosphor wheels in projector illumination systems suffer from low brightness and high fabricating costs due to poor conversion efficiency of red phosphor agents, leading to decreased illuminance and image quality when the driving current of blue light lasers increases.
Innovation Solution
A phosphor wheel utilizing a yellow phosphor agent instead of conventional red phosphor agents, combined with a red light filter, to enhance the brightness of red light and overall illumination system efficiency, while reducing fabricating costs and enabling active 3D image-projection technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a red phosphor agent is used to convert blue light to red light, then the illumination system can produce red light, but the conversion efficiency is poor resulting in low brightness and high fabricating costs
Solution Approach 1:
The patent introduces a yellow phosphor agent as an intermediary substance that converts blue light to yellow light with high efficiency, and then a red light filter acts as another intermediary to convert the yellow light to red light. This two-step process via yellow phosphor and filter achieves better conversion efficiency and higher red light brightness compared to using red phosphor directly.
2Adaptability or versatility
If the size of the red phosphor agent segment is increased to improve color performance, then the color performance is enhanced, but the brightness of white light output becomes too low and fabricating cost increases
Solution Approach 1:
The patent changes the fundamental parameter of the phosphor agent from red phosphor to yellow phosphor, which has different optical characteristics. The yellow phosphor agent has broader spectral coverage and higher conversion efficiency, allowing for smaller segment size while maintaining or improving color performance and white light brightness simultaneously.
3Power
If the driving current of blue light laser is increased to improve illumination output, then the luminance and illuminance of red light decay, affecting sharpness and contrast
Solution Approach 1:
The patent changes the phosphor conversion pathway from direct red phosphor to yellow phosphor plus red light filter. This parameter change in the optical conversion process eliminates the saturation effect where increasing blue light current no longer increases red light output. The yellow phosphor provides a more linear and stable conversion characteristic that maintains red light luminance stability even at higher driving currents.
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 yellow phosphor agent and red light filter combination increases red light brightness with increasing blue light laser current, improving overall brightness and image quality, and reduces the phosphor wheel's size, allowing for larger blue, green, and yellow regions for active 3D applications, with a 30% increase in red light illuminance and lower production costs.
Implementation Method 1
a yellow phosphor agent to convert the blue light to a yellow light with a longer wavelength
Implementation Method 2
a red light filter to convert the yellow light to a red light
Data Source
AI summary
A phosphor wheel includes a glass, a first phosphor agent and a first filter. The glass has a first region and the first phosphor agent is coated on the first region for converting a first color light into a second color light. The first filter is disposed next to the first region for filtering at least a portion of the first color light and a first light beam of the second color light, so that a second light beam of the second color light is transmitted through the first filter. The second color light is yellow light, the first phosphor agent is yellow phosphor agent, and the first filter is a red light filter. The present invention achieves the advantages of decreasing the fabricating cost, increasing the brightness of the red light with increasing of driving current and the whole brightness of the illumination system, and improving the image quality.