Equalized Optical Path Lengths for Projector Color Uniformity
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Solution Overview
Problem
Projector systems using light emitting diodes and fluorescent substances suffer from color irregularity due to differences in optical path lengths for blue excitation light, yellow fluorescence, green light, and red light, leading to uneven luminous intensity distributions and poor image quality.
Innovation Solution
A light source apparatus with a rotary driver, optical plate, excitation light source, convergence optical system, transfer optical system, first casting optical system, and second casting optical system, where the optical path lengths from the optical plate to a common casting plane and from the transfer plane to the common casting plane are equalized, ensuring uniform light distribution for blue excitation light and green fluorescence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different light sources (blue LED, green LED, red LED) and fluorescent substances are used to generate multiple colors, then the projector can produce full-color images, but the optical path lengths for different colors become unequal, causing color irregularity
Solution Approach 1:
The optical system is divided into multiple independent optical paths, each handling a specific color channel (blue LED path, green LED path, red LED path, and fluorescent conversion path). Each path is independently optimized and adjusted to ensure that despite different physical paths, the optical path lengths are equalized at the DMD, thereby maintaining color uniformity while achieving full-color capability.
2Adaptability or versatility
If a spinning color wheel with fluorescent substance is used to convert blue light to yellow fluorescence, then yellow light can be generated, but the optical path length for yellow fluorescence differs from blue excitation light, causing luminous intensity distribution differences
Solution Approach 1:
A yellow fluorescence generating member (spinning color wheel with fluorescent substance) is introduced as an intermediary component between the blue LED and the DMD. This member converts blue light to yellow fluorescence while allowing both the blue excitation light and yellow fluorescence to pass through. The optical system is designed with equal optical path lengths from the yellow fluorescence generating member to the DMD for both blue and yellow light, ensuring uniform luminous intensity distribution.
3Adaptability or versatility
If multiple independent light sources and optical paths are combined, then full-color projection is achieved, but the device complexity increases
Solution Approach 1:
The optical system is designed with universal components that serve multiple functions. For example, the DMD and projection lens are shared across all color channels (blue, green, red, and fluorescent-converted light). The optical paths are configured to converge at common points, allowing a single DMD and projection system to handle all color channels, thereby reducing overall device complexity while maintaining full-color capability.
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 minimizes color irregularity by ensuring equal optical path lengths for excitation light and fluorescence, resulting in uniform luminous intensity distributions and improved image quality, reducing production costs through standardized components and minimizing apparatus size.
Implementation Method 1
a fluorescent substance layer which converts the excitation light to fluorescence
Implementation Method 2
a convergence optical system which converges the excitation light emitted from the excitation light source unit to the translucent segment and to the fluorescent substance layer
Data Source
AI summary
A light source apparatus includes an optical plate, a convergence optical system, a transfer optical system and two casting optical systems. The optical plate includes a translucent segment and a fluorescent substance layer. The convergence optical system converges an excitation light to the translucent segment and to the fluorescent substance layer. The transfer optical system transfers a spot of the excitation light to a transfer plane of the optical plate. The first casting optical system projects a light source image of fluorescence, which is formed on the fluorescent substance layer, onto a common casting plane. The second casting optical system which projects the spot of the excitation light onto the common casting plane. Optical path lengths of the two casting optical systems are the same.