Projector Polarization Recycling for Higher Light Use Efficiency
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Solution Overview
Problem
Existing projection systems using spatial light modulators with diffraction patterns face challenges such as increased size, cost, and decreased light use efficiency due to zero-order and high-order diffraction losses, requiring complex calculations and large pixel sizes.
Innovation Solution
A projector configuration that utilizes a light source, light combiner, light modulation portion, light separation portion, projection optical apparatus, and polarization converter to separate and recycle image non-generation light by aligning polarization directions, eliminating the need for diffraction and reducing system size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a spatial light modulator using diffraction patterns is used to control illumination light intensity, then the brightness of the input image can be adjusted, but the system size increases and cost increases
Solution Approach 1:
The patent extracts the light modulation function from a complex spatial light modulator and implements it using a simpler liquid crystal display panel. The SLM is replaced by combining a liquid crystal panel with a polarization converter and beam splitter, removing the need for complex diffraction pattern generation while maintaining brightness control capability
Solution Approach 2:
The patent uses a liquid crystal display panel to copy the light modulation function of the spatial light modulator. Instead of using diffraction patterns, the liquid crystal panel modulates light intensity through polarization control, achieving the same brightness adjustment effect with simpler technology
2Illumination intensity
If a spatial light modulator using diffraction patterns is used to control illumination light intensity, then the brightness of the input image can be adjusted, but the cost increases
Solution Approach 1:
The patent replaces the expensive spatial light modulator with more cost-effective components: a liquid crystal display panel, polarization converter, and beam splitter. These components are commercially available and less expensive than specialized SLM devices, reducing the overall system cost while maintaining the brightness control function
3Illumination intensity
If diffraction patterns are used in the spatial light modulator, then light intensity can be modulated, but zero-order light and high-order diffraction images cause diffraction loss and decrease light use efficiency
Solution Approach 1:
The patent converts the previously wasted light (zero-order and high-order diffraction images) into useful illumination light through the light recycling unit. The beam splitter separates modulated light into image light and illumination light, and the illumination light is redirected back to illuminate the liquid crystal panel again, turning energy loss into energy utilization
Solution Approach 2:
The patent recovers illumination light that would otherwise be discarded after passing through the liquid crystal panel. The light recycling unit captures this light and redirects it back to the panel, enabling multiple uses of the same light and significantly improving light use efficiency
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
Enhances light use efficiency by recycling non-generation light, minimizing diffraction losses, and reducing the projector's size and cost compared to systems using spatial light modulators.
Implementation Method 1
a polarization converter disposed in an optical path between the light combiner and the light modulation portion and configured to align polarization directions of light incident from the light combiner
Implementation Method 2
the illumination light output from the light source being light polarized in a first polarization direction with respect to the light combiner, and the image non-generation light caused to enter the light combiner by the light guide system being light polarized in a second polarization direction perpendicular to the first polarization direction with respect to the light combiner
Data Source
AI summary
A projector according to an aspect of the present disclosure includes a light source configured to output illumination light, a light combiner that the illumination light enters, a light modulation portion configured to modulate light incident from the light combiner to generate image modulated light, a light separation portion configured to separate the image modulated light into image generation light that is used to generate an image and image non-generation light that is not used to generate the image, a projection optical apparatus configured to project the image generation light, a light guide system configured to guide the image non-generation light incident from the light separation portion to the light combiner, and a polarization converter disposed in an optical path between the light combiner and the light modulation portion and configured to align polarization directions of the light incident from the light combiner, the illumination light being light polarized in a first polarization direction with respect to the light combiner, the image non-generation light that enters the light combiner being light polarized in a second polarization direction with respect to the light combiner, and combined with the illumination light incident from the light source in the light combiner, and caused to enter the light modulation portion.