Off-Center Dichroic Mirror for Projector Light Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional projectors suffer from reduced light use efficiency due to the inefficient guidance of blue light through dichroic mirrors, leading to a significant portion of the light not being directed to the light tunnel.
Innovation Solution
The light source device incorporates a dichroic mirror positioned off-center to reflect blue light from the excitation source, allowing it to be guided obliquely to the fluorescent wheel, where it is diffused and reflected, while the green and red light sources are optimized using composite dichroic mirrors to enhance light transmission and reflection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If blue light passes through only the central area of the dichroic mirror, then the optical path is simplified, but light use efficiency decreases due to unguided light loss
Solution Approach 1:
The dichroic mirror is divided into multiple functional areas: a first area for reflecting blue light to the light tunnel, a second area for reflecting blue light to the fluorescent wheel, and a third area for transmitting blue light. This segmentation allows different portions of the mirror to handle different light paths efficiently, resolving the contradiction between optical path simplicity and light utilization efficiency.
Solution Approach 2:
Different regions of the dichroic mirror are assigned different optical functions (reflection at specific angles, transmission) based on local requirements. The first area reflects blue light obliquely to the light tunnel, the second area reflects blue light to the fluorescent wheel, and the third area transmits blue light, optimizing light guidance in each local zone to improve overall light use efficiency.
2Ease of operation
If the dichroic mirror is positioned on the optical axis, then the optical alignment is simplified, but light guidance efficiency decreases due to light passing through without proper reflection
Solution Approach 1:
The dichroic mirror is positioned asymmetrically relative to the optical axis, with its surface oriented at a specific angle (e.g., 45 degrees) to the optical axis. This asymmetric positioning enables effective oblique reflection of blue light to both the light tunnel and the fluorescent wheel, improving light guidance efficiency while maintaining manageable optical alignment through defined angular relationships.
3Illumination intensity
If blue light is reflected by the diffuse layer of the fluorescent wheel, then green light generation is enabled, but light loss occurs due to incomplete reflection guidance
Solution Approach 1:
The dichroic mirror's second area is specifically designed to reflect blue light onto the fluorescent wheel's diffuse layer, enabling green light generation through fluorescence excitation. This segmented approach ensures dedicated blue light delivery to the fluorescent material while the first area simultaneously guides blue light to the light tunnel, minimizing overall light loss.
Solution Approach 2:
The dichroic mirror acts as an intermediary device that efficiently transfers blue light from the light source to both the light tunnel and the fluorescent wheel. By providing dedicated reflection paths, it ensures maximum blue light utilization for green light generation while minimizing waste.
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 improves the light use efficiency by minimizing light loss and ensuring that more of the blue, green, and red wavelengths are effectively directed to the light tunnel, resulting in brighter and more efficient color image projection.
Implementation Method 1
a dichroic mirror positioned off-center to reflect blue light from the excitation source
Implementation Method 2
composite dichroic mirrors to enhance light transmission and reflection efficiency
Implementation Method 3
fluorescent wheel having a green-light emitting area which uses excitation light emitted from the excitation light source to emit light of a green wavelength band
Implementation Method 4
where it is diffused and reflected
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light source device (60, 60A, 60B) comprising a first light source (70, 70A), a second light source (80) and a dichroic mirror (77), the first light source being configured to emit excitation light, the second light source being configured to emit fluorescent light by being irradiated with the excitation light, wherein the dichroic mirror is disposed on an emission side of the second light source and is configured to reflect the excitation light while transmitting the fluorescent light and an intersection of the optical axis (L1) of the excitation light and the dichroic mirror is apart from the center of the optical axis (L2) of the fluorescent light; and corresponding projector.