Light Source Unit with Dichroic Filter Angle Management
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Solution Overview
Problem
Existing light source units for projectors, such as those described in Japanese Patent Laid-Open No. 2012-212129, face challenges in reducing size due to the difficulty in time-sharing emission of light in the blue, red, and green wavelength ranges, particularly because excitation light is shined onto a rotating wheel, making it hard to efficiently manage light emission angles.
Innovation Solution
A light source unit configuration that includes a first and second light source emitting light in a first wavelength range, a luminescent plate excited to emit light in a second wavelength range, and a dichroic filter with specific incident angle ranges for each light source, allowing light in the first wavelength range to be reflected and light in the second wavelength range to be transmitted, enabling efficient emission of blue, green, and red light through precise angle management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If excitation light is shined onto a rotating wheel with luminescent material layers to emit light in blue, red, and green wavelength ranges in a time-sharing manner, then color image projection is achieved, but the size of the light source unit cannot be reduced further
Solution Approach 1:
The patent divides the light source unit into multiple independent light sources (first light source, second light source, third light source) each emitting light in the first wavelength range, which then excite different regions of the luminescent plate. This segmentation eliminates the need for a rotating wheel while maintaining color image projection capability through spatial rather than temporal separation of color channels.
Solution Approach 2:
Instead of using a rotating wheel to sequentially present different luminescent material layers to a single excitation light source, the patent inverts the approach by using multiple stationary light sources simultaneously exciting different regions of the luminescent plate. This inversion from temporal to spatial multiplexing reduces mechanical complexity and size.
2Adaptability or versatility
If a rotating wheel with luminescent material layers is used to emit light in different wavelength ranges, then color image projection is achieved, but the configuration becomes complex and difficult to simplify
Solution Approach 1:
The patent extracts and removes the rotating wheel component from the system, replacing it with a stationary luminescent plate and multiple light sources. This extraction eliminates the mechanical rotation mechanism and associated complexity while maintaining the essential function of generating blue, green, and red light for color image projection.
Solution Approach 2:
The patent replaces the mechanical rotating wheel system with a static optical system consisting of multiple light sources and a luminescent plate. This substitution eliminates moving parts and mechanical complexity while achieving the same color image projection function through optical means.
3Productivity
If light in the first wavelength range is incident on the dichroic filter at different angles from multiple light sources, then efficient light separation is achieved, but precise angle management is required
Solution Approach 1:
The patent positions each light source (first, second, and third light sources) at specific locations and orientations relative to the luminescent plate and dichroic filter, creating localized optical paths with controlled incident angles. Each light source is optimized for its specific function (blue light generation, green light generation, red light generation) with precise angular positioning to ensure efficient light separation while managing the complexity of angle control.
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 simplifies the light source unit and projector design, allowing for effective time-sharing emission of blue, green, and red light, improving color image projection while reducing the overall size of the light source unit.
Implementation Method 1
a dichroic filter provided on one surface side of the luminescent plate and configured to transmit the light in a second wavelength range
Implementation Method 2
a luminescent plate configured to be excited by the light in a first wavelength range to emit light in a second wavelength range
Data Source
AI summary
A light source unit of the present invention includes a first light source and a second light source that are configure to emit light in a first wavelength range, a luminescent plate configured to be excited by the light in a first wavelength range to emit light in a second wavelength range, and a dichroic filter provided on one surface side of the luminescent plate and configured to transmit the light in a second wavelength, and the light in a first wavelength range emitted from the first light source is incident on the dichroic filter at an angle within a first incident angle range, and the light in a first wavelength range emitted from the second light source is incident on the dichroic filter at an angle within a second incident angle range that is greater than the first incident angle range.