Light Source Device for Projectors Using Segmented Polarization Conversion
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Solution Overview
Problem
Existing projector technologies face challenges in reducing size due to the difficulty in manufacturing narrow-pitch polarization conversion elements, leading to increased energy density and potential damage to liquid crystal panel sub-pixels, especially those irradiated with blue light, which affects reliability and light use efficiency.
Innovation Solution
A light source device that emits polarized blue, red, and green light beams spatially separated without using narrow-pitch polarization conversion elements, utilizing a configuration with polarization split elements, retardation elements, and wavelength conversion elements to alternate the emission of blue and red light beams, reducing the risk of continuous blue light exposure and enhancing light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a polarization conversion element with narrow pitch is used to reduce device size, then the projector size can be reduced, but it becomes difficult to manufacture and the reliability deteriorates
Solution Approach 1:
The polarization conversion function is divided into separate components: a polarization beam splitter and a retardation element. This segmentation eliminates the need for narrow-pitch integrated polarization conversion elements, making each component manufacturable with standard processes while maintaining compact overall device size through optimized spatial arrangement.
Solution Approach 2:
The retardation element is positioned within the optical path between the polarization beam splitter and the liquid crystal panel, creating a nested configuration where multiple functional elements occupy overlapping or adjacent spaces. This nesting allows achieving polarization conversion functionality without requiring narrow pitch between separate components, thus improving manufacturability while maintaining compact size.
2Device complexity
If a single liquid crystal panel is used to modulate all colors, then device complexity is reduced, but energy density increases causing damage to sub-pixels especially those irradiated with blue light
Solution Approach 1:
The liquid crystal panel is divided into multiple regions with different polarization transmission characteristics. By segmenting the panel into areas that transmit different polarization directions for different color wavelengths, the energy load on any single sub-pixel region is reduced, preventing damage from continuous high-energy blue light irradiation while maintaining single-panel simplicity.
Solution Approach 2:
Different regions of the liquid crystal panel are designed with locally optimized properties: some regions are optimized for transmitting blue light with specific polarization, while other regions handle red and green wavelengths. This local quality differentiation allows the single panel to manage high energy density by distributing the optical load across specialized zones rather than uniformly across all pixels.
3Adaptability or versatility
If unpolarized light from a lamp source is used to illuminate the liquid crystal display element, then light source versatility is maintained, but polarization uniformity is insufficient requiring additional polarization conversion elements
Solution Approach 1:
A polarization beam splitter is introduced as an intermediary element between the unpolarized lamp light source and the liquid crystal panel. This mediator converts the unpolarized light into spatially separated polarized beams, providing the polarization uniformity required by the liquid crystal display while allowing continued use of versatile unpolarized lamp sources. The beam splitter acts as the intermediary that reconciles the incompatibility between unpolarized source light and polarized display requirements.
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 allows for a compact projector design with improved light source efficiency and reduced risk of sub-pixel damage, enabling efficient emission of multiple colored light beams and enhancing the reliability of the liquid crystal panel.
Implementation Method 1
a first polarization split element configured to transmit the first light beam which is polarized in the first polarization direction and enters the first polarization split element along a first direction from the light source section toward the first direction, and configured to reflect the first light beam which is polarized in the second polarization direction toward a second direction crossing the first direction
Implementation Method 2
a first retardation element disposed at the first direction side of the first polarization split element, and configured to convert the first light beam which is polarized in the first polarization direction and enters the first retardation element along the first direction from the first polarization split element into the first light beam polarized in the second polarization direction
Implementation Method 3
a light conversion device having a diffusion element configured to diffuse the first light beam which enters the diffusion element along the second direction from the second retardation element to emit the first light beam diffused toward a third direction as an opposite direction to the second direction
Implementation Method 4
a first wavelength conversion element configured to perform wavelength conversion on the first light beam which enters the first wavelength conversion element along the second direction from the second retardation element to emit a second light beam having a second wavelength band different from the first wavelength band toward the third direction
Data Source
AI summary
A light source device according to the present disclosure includes a light source section, a first polarization split element for transmitting first light with a first polarization direction from the light source section and reflecting the first light with a second polarization direction, a first retardation element, a second polarization split element for reflecting the first light in the second polarization direction from the first retardation element, a second retardation element, and a light conversion device having a diffusion element for diffusing the first light from the second retardation element, a first wavelength conversion element for performing wavelength conversion on the first light to emit second light, and a substrate.