Off-Axis Projection Light Source for Elliptical Spot Matching
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Solution Overview
Problem
Existing projection display systems using blue laser light sources suffer from brightness loss due to absorption in spectroscopic elements and mismatched light spot shapes, leading to reduced light utilization and efficiency.
Innovation Solution
A light source system with an off-axis configuration, including a light guiding assembly and homogenizing element, which uses a first lens group to focus light on a wavelength conversion region and reflection region, and an adjustable element to shape the light spot elliptically, improving light utilization and matching the light spot to the homogenizing element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spectroscopic sheet with thickness of 0.5 mm to 1.1 mm is used to transmit blue light and reflect fluorescence, then the light guiding function is achieved, but blue light absorption causes brightness loss of 2% to 5%
Solution Approach 1:
The patent extracts the light guiding function from the spectroscopic sheet by introducing a dedicated light guiding assembly. This assembly uses a light guiding element with specific refractive index and a reflection element, separating the light guiding task from the wavelength conversion task performed by the spectroscopic sheet, thereby reducing unnecessary blue light absorption.
Solution Approach 2:
The patent introduces a light guiding element as an intermediary component between the light source and the spectroscopic sheet. This element has optimized optical properties (refractive index between 1.3-1.7) that minimize blue light absorption while effectively guiding light, acting as a mediator that improves light transmission efficiency.
2Device complexity
If a circular focused spot of blue laser is used in a conventional system, then the light source configuration is simple, but it does not match the rectangular spatial light modulator (aspect ratio 16:9), greatly reducing system efficiency
Solution Approach 1:
The patent applies asymmetry by transforming the circular light spot into an elliptical light spot with specific aspect ratio (4:3 or 16:9). This is achieved through asymmetric optical elements (cylindrical lenses or asymmetric reflection elements) that stretch the light spot in one dimension, making it match the rectangular spatial light modulator and improve filling efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the light spot from circular (equal dimensions in all directions) to elliptical (different dimensions in different directions). By adjusting the aspect ratio of the elliptical spot to match the spatial light modulator, the system achieves better parameter matching and improved efficiency.
3Device complexity
If the optical axis of blue laser is aligned with the first lens group, then the optical path is simple, but the light spot shape does not match the homogenizing element, reducing light utilization rate
Solution Approach 1:
The patent introduces asymmetric optical elements (cylindrical lenses or asymmetric reflection elements) that break the symmetric optical path. These elements selectively focus light in one dimension while leaving the other dimension unaffected, creating an elliptical light spot that matches the homogenizing element's rectangular aperture, thereby improving light utilization.
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 system enhances light utilization and brightness by reducing loss and shaping the light spot to match the homogenizing element, thereby improving the overall efficiency of the projection device.
Implementation Method 1
the first-color light generated by the light source is incident on the first lens group. When the first-color light is incident on the wavelength conversion region after being focused by the first lens group
Implementation Method 2
the wavelength conversion region is excited by the first-color light to emit a second-color light
Implementation Method 3
the first-color light is reflected by the reflection region, and is incident on the light guiding assembly through the first lens group
Implementation Method 4
the first-color light or the second-color light that is incident on the light guiding assembly is incident on the light homogenizing element through the light guiding assembly
Implementation Method 5
then exits after being homogenized by the light homogenizing element
Data Source
Figure 1~2(2)
Figure 3~4
Figure 5~6
AI summary
A light source system and a projection device. In the light source system, when a light source (01) and a lens group (03) are off-axis, that is, light generated by the light source (01) is directly incident into the lens group (03) via a light guide element (02) or an avoidance light guide element (02), the optical axis of a light spot and the optical axis of the lens group are spaced apart by a certain distance. After being focused by the lens group, the light serves as excitation light of a wavelength conversion region, so that loss of light of a first color and excited light of a second color on the light guide element (02) may be reduced. Moreover, when the excited light of a second color is finally incident into a light homogenizing element (12), the formed light spot may be oval and corresponds to long and short edges of the light homogenizing element (12), thereby improving the utilization rate of the light, so that the brightness of the projection device may be improved.