Projector Light Source Polarization Control for Speckle Reduction
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Solution Overview
Problem
Existing light source apparatuses in projectors using laser light sources produce speckles due to coherent laser light interference, leading to deteriorated display quality.
Innovation Solution
A light source apparatus with a first light source, a wavelength converter, a second light source, and a controller to control the ratio of light emission from laser diodes with different polarization states, combined with a polarization converter to manage speckle interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light source is used to provide blue light component, then light output intensity is improved, but speckle interference occurs deteriorating display quality
Solution Approach 1:
The patent applies dynamics by making the polarization state of the blue light time-varying. The controller dynamically adjusts the ratio of P-polarized to S-polarized light from the laser diodes, changing the polarization characteristics over time to prevent fixed speckle patterns and improve display quality while maintaining high light output intensity.
2Shape
If fixed diffuser is used to diffuse blue light, then light distribution is improved, but speckle suppression is insufficient
Solution Approach 1:
Instead of using a static diffuser, the patent employs dynamic polarization control. The controller varies the polarization ratio of the blue light over time, which dynamically changes the speckle pattern and provides superior speckle suppression compared to fixed diffusers, while still achieving uniform light distribution.
Solution Approach 2:
The patent changes the polarization parameter of the blue light by adjusting the ratio of P-polarized to S-polarized light emitted by the laser diodes. This parameter change over time effectively suppresses speckles while maintaining good light distribution, overcoming the limitations of fixed diffusers.
3Object-affected harmful factors
If multiple laser diodes with different polarization states are used, then speckle interference is reduced, but device complexity increases
Solution Approach 1:
The patent segments the blue light source into multiple laser diodes with different polarization states (P-polarized and S-polarized). By dividing the light source function across multiple diodes, the system can independently control each polarization component to reduce speckle interference while keeping the overall structure relatively simple.
Solution Approach 2:
The patent combines multiple laser diodes with different polarization characteristics into a single integrated light source unit. The controller merges the outputs of these diodes by adjusting their polarization ratios, achieving speckle suppression while presenting a unified interface that minimizes system complexity.
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 reduces speckle interference, enhancing display quality by temporally changing the ratio of P-polarized and S-polarized blue light emission, improving image clarity in projectors.
Implementation Method 1
a wavelength converter configured to convert the first light into second light having a second wavelength band different from the first wavelength band
Implementation Method 2
The third light includes fourth light in a first polarization state, and fifth light in a second polarization state different from the first polarization state
Data Source
AI summary
A light source apparatus according to an aspect of the present disclosure includes: a first light source configured to output first light; a wavelength converter configured to convert the first light into second light; a second light source configured to output third light; a light guide configured to guide the first light, the second light, and the third light; and a controller configured to control a state in which the second light source outputs the third light. The wavelength converter has a first surface, a second surface, and a third surface. The first light enters the wavelength converter through the third surface via the light guide. The second light travels through the light guide and exits out of a region on the first surface side of the light guide. The third light includes fourth light in a first polarization state, and fifth light in a second polarization state, and enters a region on the second surface side of the light guide. The second light source includes a first light emitting section configured to emit the fourth light and a second light emitting section configured to emit the fifth light. The light emitting sections each include a laser diode. The controller is configured to temporally change a ratio between an amount of the fourth light and an amount of the fifth light.