Light Source Device Polarization Conversion for Projector Color Purity
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Solution Overview
Problem
Existing light source devices for projectors suffer from decreased color purity due to unexcited excitation light being reflected back and mixed with fluorescent light, leading to color mixture and reduced reproducibility.
Innovation Solution
A light source device configuration featuring a light emitting element, a fluorescent wheel with both fluorescent and transmission areas, a dichroic mirror that reflects S-polarized light and transmits P-polarized light, and a polarization conversion element that converts light between these polarization directions, along with a reflection member to optimize light path and reduce optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dichroic mirror is used to separate excitation light and fluorescent light, then light path separation is achieved, but unexcited excitation light is reflected back and mixes with fluorescent light, decreasing color purity
Solution Approach 1:
The wheel is divided into fluorescent areas and transmission areas. The transmission areas allow unexcited excitation light to pass through without reflection, preventing it from mixing with fluorescent light. This segmentation resolves the contradiction by creating separate optical paths for different light components.
Solution Approach 2:
The patent extracts the problematic reflected excitation light by introducing transmission areas that allow this light to pass through directly to the illumination optical system, separating it from the fluorescent light path and eliminating color mixture.
2Ease of operation
If a polarization conversion element is added to convert polarization direction, then light path control is improved, but device complexity increases
Solution Approach 1:
The polarization conversion element serves multiple functions: it converts polarization direction of transmitted excitation light and also converts polarization direction of reflected excitation light before it reaches the dichroic mirror. This multi-functionality justifies the added component by achieving multiple light control objectives with a single element.
Solution Approach 2:
The polarization conversion element performs preliminary conversion of the polarization direction of excitation light before it reaches the dichroic mirror. This preliminary action ensures that the dichroic mirror can properly separate the light paths, improving overall light path control.
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 enhances color reproducibility by minimizing optical path losses and ensuring that light is effectively utilized, resulting in improved color purity and image quality with a simple and efficient design.
Implementation Method 1
The fluorescent wheel includes a fluorescent area configured to convert the light of the first wavelength band into fluorescent light
Implementation Method 2
The dichroic mirror is configured to reflect a component in a first polarization direction of the light of the first wavelength band emitted from the light emitting element, to transmit a component in a second polarization direction
Implementation Method 3
The polarization conversion element is disposed between the fluorescent wheel and the reflection member, configured to transmit the light of the first wavelength band transmitted through the transmission area and the light of the first wavelength band reflected by the reflection member, and configured to convert the light of the first wavelength band in the first polarization direction into the second polarization direction
Data Source
AI summary
A light source device includes a light emitting element emitting light of a first wavelength band, a fluorescent wheel, a dichroic mirror, a reflection member and a polarization conversion element. The fluorescent wheel includes a fluorescent area converting the light of the first wavelength band into fluorescent light and a transmission area transmitting the light of the first wavelength band. The dichroic mirror reflects the light of the first wavelength band a first polarization direction, transmits the light in a second polarization direction, and transmits or reflects the fluorescent light. The reflection member reflects the light transmitted through the transmission area toward the transmission area. The polarization conversion element is disposed between the fluorescent wheel and the reflection member, transmits the lights transmitted through the transmission area and reflected by the reflection member, and converts the light in the first polarization direction into the second polarization direction.