Cubical Dichroic Prism Light Source Unit for Projectors
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Solution Overview
Problem
Current light source units for projectors, which utilize high-luminance extra-high pressure mercury vapor or metal halide lamps, face issues with heat management, leading to complex and large cooling mechanisms, and existing LED-based solutions suffer from reduced light utilization efficiency due to stray light dispersion in dichroic prisms.
Innovation Solution
A light source unit featuring a cubical dichroic prism with specific incident and emitting surfaces, combined with filters on non-emitting surfaces to selectively pass and reflect wavelengths, enhancing light combination and reducing stray light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-luminance extra-high pressure mercury vapor or metal halide lamps are used, then luminance is improved, but heat generation increases requiring complex cooling mechanisms
Solution Approach 1:
The patent replaces traditional high-luminance lamps (mercury vapor or metal halide) with light emitting diodes (LEDs) as the light source. This substitution eliminates the need for complex cooling mechanisms while maintaining sufficient luminance for projector operation, directly resolving the contradiction between luminance and heat generation.
2Productivity
If light sources are arranged to face three sides of a dichroic prism, then light combination is achieved, but stray light leaks out reducing utilization efficiency
Solution Approach 1:
The patent extracts and removes stray light from the optical system by positioning the screen at a specific angle relative to the dichroic prism. This angular arrangement causes stray light to be directed away from the projection path, preventing it from reaching the screen and thereby improving light utilization efficiency.
Solution Approach 2:
The patent introduces an angular dimension to the optical arrangement by positioning the screen at a specific angle rather than parallel to the prism faces. This dimensional change in the optical path geometry enables stray light to be separated from the useful light path, resolving the contradiction between light combination and stray light prevention.
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 light utilization efficiency by directing light parallel to the optical axis, reducing stray light and enhancing the projector's luminance and image quality.
Implementation Method 1
a dichroic prism, wherein the dichroic prism is formed substantially into a cubical shape which has a plurality of incident surfaces which correspond to the plurality of light sources, respectively, and an emitting surface so as to combine light rays from the respective light sources
Implementation Method 2
light rays from the respective light sources for emission therefrom
Implementation Method 3
filters are formed on two of the incident surfaces which do not face the emitting surface of the dichroic prism which filters let in light of wavelengths corresponding, respectively, to the light sources which the filters face pass through and reflect light of all other wavelengths
Data Source
AI summary
The invention was made to provide a light source unit which can enhance the utilization efficiency of the dichroic prism which emits light that is emitted from a plurality of light sources in a direction which is parallel to an optical axis and a projector which employs the light source. The light source unit has a first light source, a second light source and a third light source which have different colors and includes a substantially cubical dichroic prism which combines light from the respective light sources for emission thereof. One of surfaces which intersect an optical axis of the dichroic prism is made to constitute a first incident surface, a surface which faces the first incident surface is made to constitute an emitting surface, and side surfaces are made to constitute a second incident surface and a third incident surface, respectively. The first light source is disposed in the vicinity of the first incident surface, the second light source is disposed in the vicinity of the second incident surface, and the third light source is disposed in the vicinity of the third incident surface, and the first incident surface, the second incident surface and the third incident surface are made up of filters which let light from the first light source, the second light source and the third light source pass through and reflect light of all other colors.