Light Source Device Polarization Control Speckle Noise
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Solution Overview
Problem
Existing light source devices using laser light sources face issues with luminance unevenness and speckle noise in projected images, which previous solutions have not adequately addressed.
Innovation Solution
A light source device comprising a solid-state light source unit, a dichroic mirror, a fluorescent plate, a first wave plate, and a multi-reflection mirror, which emits orthogonal linearly polarized light rays, separates and combines blue and yellow light, and uses a multi-reflection mirror to reflect circularly polarized light, effectively reducing luminance unevenness and speckle noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a laser light source is used, then the light source device can be simplified and miniaturized, but luminance unevenness and speckle noise occur in projected images
Solution Approach 1:
The patent segments the laser beam into multiple separate beams using beam splitting elements, then recombines them after individual processing. This segmentation allows each beam to be treated independently to reduce speckle noise while maintaining the overall laser light source structure
Solution Approach 2:
The patent embeds multiple optical processing elements (beam splitters, wave plates, diffusers) within a compact nested arrangement where smaller optical components are positioned within the optical path of larger components, achieving miniaturization while maintaining functionality
2Volume of moving object
If a simple laser light source is used, then the device can be miniaturized, but luminance unevenness occurs in projected images
Solution Approach 1:
The patent introduces a temporal dimension by dynamically modulating the laser beams through rotating diffusers or acousto-optic modulators, converting a spatial uniformity problem into a temporal averaging problem that reduces luminance unevenness without increasing system volume
Solution Approach 2:
The patent introduces intermediary optical elements (wave plates, diffusers, beam combiners) that mediate between the laser source and the projection medium, transforming the beam characteristics to achieve uniform luminance while keeping the overall system compact
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 effectively prevents luminance unevenness and speckle noise in projected images, even with a simple laser light source, while also miniaturizing the optical system.
Implementation Method 1
a solid-state light source unit (101-105)
Implementation Method 2
a dichroic mirror (107) that separates the first linearly polarized light ray and the second linearly polarized light ray
Implementation Method 3
a fluorescent plate (105) that emits yellow light to the dichroic mirror (107) when the fluorescent plate is excited by the first linearly polarized light ray
Implementation Method 4
a first wave plate (111) that converts the second linearly polarized light ray separated by the dichroic mirror, into circularly polarized light
Implementation Method 5
a multi-reflection mirror (112) that reflects the circularly polarized light to the dichroic mirror as the blue light
Data Source
AI summary
The light source device and the projection display apparatus include a solid-state light source unit, a dichroic mirror, a fluorescent plate, a first wave plate, and a multi-reflection mirror. The solid-state light source unit emits first and second linearly polarized light rays at a predetermined ratio, the first and the second linearly polarized light rays being orthogonal to each other. The dichroic mirror separates the first and the second linearly polarized light rays, and combines blue light with yellow light. The fluorescent plate emits the yellow light to the dichroic mirror when the fluorescent plate is excited by the first linearly polarized light ray separated by the dichroic mirror. The first wave plate converts the second linearly polarized light ray separated by the dichroic mirror, into circularly polarized light. The multi-reflection mirror reflects the circularly polarized light to the dichroic mirror as the blue light.