Illumination Apparatus Using Polarization Segmentation for Single Prism Color Combination
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Solution Overview
Problem
Projection display apparatuses using four or more colors require multiple dichroic cubes to combine light beams, increasing cost and back focus, as a single cross dichroic cube cannot effectively combine multiple color light beams, compromising color reproducibility and brightness.
Innovation Solution
An illumination apparatus with a light source, color separators, light valves, and a polarization-state adjusting element that separates and adjusts the polarization state of white light into red, green, and blue components, allowing for a single cross dichroic prism to combine these colors without altering the projection lens design, enabling switching between color reproducibility and brightness priority modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple dichroic cubes are used to combine light beams of four or more colors, then color reproducibility and brightness are improved, but device complexity and cost increase
Solution Approach 1:
The green wavelength band is segmented into three sub-bands (first, second, and third green wavelength bands) with different polarization states. This segmentation allows each sub-band to be processed independently through the single cross dichroic cube, enabling multi-color light combination without requiring multiple dichroic cubes.
Solution Approach 2:
The invention changes the polarization state parameter of light beams by using a polarization converter for the second green wavelength band. This parameter change enables the single cross dichroic cube to distinguish and separate different green sub-bands, resolving the contradiction between using multiple dichroic cubes and maintaining device simplicity.
2Manufacturing precision
If multiple dichroic cubes are used to combine light beams of four or more colors, then color reproducibility is improved, but back focus length increases
Solution Approach 1:
By segmenting the green wavelength band into three sub-bands and assigning different polarization states to each, the invention enables precise color control through a single compact dichroic cube, maintaining short back focus while achieving high color reproducibility.
Solution Approach 2:
The polarization state parameter modification allows the single dichroic cube to achieve the color separation functionality that would otherwise require multiple stacked dichroic cubes, thereby reducing the back focus length while maintaining color reproduction quality.
3Device complexity
If a single cross dichroic cube is used to combine light beams, then device complexity is reduced, but the ability to combine four or more color light beams is limited
Solution Approach 1:
The invention applies local quality by giving different polarization characteristics to different wavelength bands within the green region. The first green band maintains original polarization, the second green band has converted polarization, and the third green band has different polarization again, allowing the single dichroic cube to handle multiple color combinations.
Solution Approach 2:
The single cross dichroic cube is made universal by combining it with polarization converters that enable it to process and separate multiple wavelength bands (red, green, blue, and yellow) that would otherwise require multiple dedicated dichroic cubes, thus achieving multi-color combination capability with a single device.
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 solution allows for improved color reproducibility and brightness in projection display apparatuses by using a single cross dichroic prism, reducing costs and maintaining the design integrity of the projection lens unit, while enhancing the purity of colors reproduced.
Implementation Method 1
a color separator (a dichroic mirror 71 and a dichroic mirror 72) configured to separate the white light emitted by the light source into a first color component light having a first wavelength band, a second color component light having a second wavelength band, and a third color component light having a third wavelength band
Implementation Method 2
The polarization-state adjusting element is configured to separately adjust a polarization state of light in the central-wavelength band and a polarization state of light in each of the short-wavelength band and the long-wavelength band
Implementation Method 3
a color combiner (a cross dichroic prism 60) configured to combine the first color component light emitted from the first light valve, the second color component light emitted from the second light valve, and the third color component light emitted from the third light valve
Data Source
AI summary
An illumination apparatus includes multiple liquid crystal panels, a polarization-state adjusting element, and a cross dichroic prism. A green component light includes a central-wavelength component light, a short-wavelength component light, and a long-wavelength component light. The polarization-state adjusting element separately adjusts a polarization state of the central-wavelength component light and each of polarization states of the long-wavelength component light and the short-wavelength component light.