Projector Polarization Separation for Light Loss Reduction
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Solution Overview
Problem
Projectors using LEDs as light sources face challenges with light loss due to increased apparent light source area, making it difficult to efficiently transmit light into downstream optical systems.
Innovation Solution
A projector design incorporating a first light emitting device emitting light with specific polarizations, a polarization separation element, a wavelength conversion element, and multiple light modulation devices to separate and convert light wavelengths, reducing light loss by optimizing light path and emission areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polarization conversion element is used to make polarization directions uniform, then the polarization directions incident to the liquid crystal panel become unidirectional, but the apparent light source area is doubled causing light loss
Solution Approach 1:
The patent divides the light path into two separate optical paths: one for the P-polarized component and one for the S-polarized component. By segmenting the light handling, the system avoids doubling the apparent light source area while still achieving polarization control. Each optical path processes one polarization component independently, preventing the light loss issue.
Solution Approach 2:
The patent extracts the P-polarized light component from the mixed polarized light using a polarization separation element, and directs it through a separate optical path. This extraction allows the S-polarized component to be handled differently, avoiding the need for a polarization conversion element that would double the apparent light source area.
2Illumination intensity
If the apparent light emission area is increased to provide uniform polarization, then the light distribution is improved, but it becomes hard to efficiently take light into the downstream optical system
Solution Approach 1:
The patent segments the illumination system into two independent optical paths, each handling a specific polarization component. This segmentation allows each path to maintain a compact light source area while still achieving uniform illumination through separate optical design, avoiding the trade-off between area and efficiency.
Solution Approach 2:
The patent applies different optical configurations to different polarization components locally. The P-polarized component path and S-polarized component path have different optical designs optimized for their respective polarization states, allowing efficient light coupling in each path without requiring a large apparent light source area.
3Illumination intensity
If blue light from LED is used and converted to yellow light through wavelength conversion, then the color output is improved, but light loss occurs during wavelength conversion
Solution Approach 1:
The patent segments the wavelength conversion process by handling P-polarized and S-polarized components separately. The P-polarized component undergoes wavelength conversion from blue to yellow, while the S-polarized component maintains its blue wavelength. This segmentation optimizes the overall light efficiency by converting only the necessary portion of the light spectrum.
Solution Approach 2:
The patent changes the wavelength parameter selectively for different polarization components. By converting only the P-polarized component from blue to yellow wavelength while keeping the S-polarized component in the blue range, the system achieves color quality improvement with minimized light loss during conversion.
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 solution enhances light use efficiency by reducing light loss and maintaining homogeneous illumination, enabling the generation of bright blue and yellow light for high-quality image display.
Implementation Method 1
a first light emitting device that emits a light having first polarization in a first wavelength range and a light having second polarization in the first wavelength range
Implementation Method 2
a wavelength conversion element, into which one of the light having the first polarization in the first wavelength range and the light having the second polarization in the first wavelength range is entered, that converts the light in the first wavelength range into light in a second wavelength range
Implementation Method 3
a polarization separation element that separates the lights into the light having the first polarization in the first wavelength range and the light having the second polarization in the first wavelength range
Data Source
AI summary
A polarization separation element that separates a light emitted from a first light emitting device into a light having first polarization in a first wavelength range and a light having second polarization in the first wavelength range, a wavelength conversion element converts the light into a light in a second wavelength range, a first light modulation device modulates the entering light according to image information, an optical element that separates the light in the second wavelength range into a light in a third wavelength range and a light in a fourth wavelength range, a second light modulation device that modulates the light according to the image information, a third light modulation device that modulates the light according to the image information, and a projection system that projects an image light are provided, wherein the wavelength conversion element has a first surface and a second surface different from the first surface.