Projector Green LED Segmentation for Light Loss
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Solution Overview
Problem
The existing 3-plate projector faces challenges in balancing light usage efficiency and color purity due to the etendue restrictions, particularly with the dichroic mirror's cutoff wavelength affecting the transmission and reflection of green light from different LEDs, leading to reduced light amount and color reproducibility.
Innovation Solution
The projector employs two green LEDs with peak wavelengths close to each other, along with a red and blue LED, using a cross dichroic prism to synthesize images and control their lighting to optimize light usage and color purity, ensuring most light is utilized while maintaining high color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dichroic mirror is used to separate green light from different LEDs, then color separation is achieved, but light loss occurs at the cutoff wavelength
Solution Approach 1:
The green light path is segmented into two separate optical paths, each handling a different green LED wavelength range. This avoids the need for a single dichroic mirror with a problematic cutoff wavelength, thereby reducing light loss while maintaining color separation effectiveness.
Solution Approach 2:
A rod integrator is introduced as an intermediary component to homogenize and redirect light from the first green LED. This intermediary element allows for better light distribution and reduces the impact of the dichroic mirror's cutoff wavelength, minimizing light loss while achieving proper color separation.
2Adaptability or versatility
If multiple green LEDs with different peak wavelengths are used, then color reproduction range is expanded, but light use efficiency is reduced due to etendue restrictions
Solution Approach 1:
The patent utilizes the wavelength dimension by employing multiple green LEDs with different peak wavelengths. This dimensional approach expands the color reproduction range while the rod integrator manages the spatial distribution to maintain light use efficiency within etendue constraints.
Solution Approach 2:
The peak wavelengths of the green LEDs are carefully selected and optimized to maximize color reproduction while minimizing light loss. By changing the wavelength parameters and optimizing their distribution, the system achieves both expanded color range and maintained light efficiency.
3Illumination intensity
If the cutoff wavelength of the dichroic mirror is adjusted, then green light transmission is improved, but color purity is reduced
Solution Approach 1:
Instead of relying on a single dichroic mirror with a compromised cutoff wavelength, the system segments the green light handling into separate paths for different wavelengths. This segmentation allows each path to optimize for its specific wavelength range, maintaining both transmission intensity and color purity.
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 light usage efficiency and color purity, allowing for a high-luminance image with improved color reproducibility by adjusting the lighting periods and currents of the LEDs to achieve optimal white balance.
Implementation Method 1
a dichroic mirror is arranged in a position where the optical axes of the first and second green LEDs intersect each other. A green optical beam emitted from the first green LED is reflected by the dichroic mirror, and the reflected light is applied to a green liquid crystal panel. A green optical beam emitted from the second green LED passes through the dichroic mirror
Implementation Method 2
A cross dichroic prism is arranged in a position where the light fluxes intersect each other. The cross dichroic prism synthesizes red image light from the red liquid crystal panel, green image light from the green liquid crystal panel, and blue image light from the blue liquid crystal panel
Implementation Method 3
Image light synthesized by the cross dichroic prism is projected to a screen by a projection lens
Implementation Method 4
first to third display elements each of which spatially modulates incident light to display an image
Data Source
AI summary
An image display method implemented in a projector that includes first to third display elements each of which spatially modulates incident light to display an image, synthesizes the images displayed by the first to third display elements, and projects the synthesized image.