Projector Illumination Device Speckle Reduction
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Solution Overview
Problem
Current projector technologies using coherent light sources suffer from speckle, a pattern of bright and dark points that cause discomfort and degrade image quality due to interference, and existing methods to reduce speckle are inadequate, often requiring larger projection lenses and increased costs.
Innovation Solution
An illumination device with multiple light emission regions, where the light source control device adjusts the light emission from each region to change the angular distribution of light over time, making the speckle pattern less visible by temporally changing the light intensity and source power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a coherent light source is used in a projector, then the wavelength band is narrow and color reproduction range is expanded, but speckle pattern appears causing discomfort and degrading image quality
Solution Approach 1:
The light source is divided into multiple independent light emission regions (first light emission region, second light emission region, etc.). Each region can be controlled independently to emit light with different angular distributions. This segmentation allows the system to switch between different light paths to change the speckle pattern temporally while maintaining the benefits of coherent light sources for color reproduction.
Solution Approach 2:
The illumination device dynamically switches between multiple light emission regions in different time periods. In the first period, the first light emission region emits light with a specific angular distribution; in the second period, the second light emission region emits light with a different angular distribution. This temporal dynamic switching changes the speckle pattern observed on the screen, making it less recognizable while maintaining narrow wavelength band benefits.
2Object-affected harmful factors
If the effective pupil (effective diameter) of the projection lens is increased to reduce speckle, then speckle reduction is achieved, but the size of the projection lens and cost increase
Solution Approach 1:
Instead of statically increasing the lens diameter, the system dynamically switches between multiple light emission regions that provide different angular distributions of light. This temporal dynamic approach achieves speckle reduction without requiring a larger lens, as the speckle pattern changes over time rather than requiring a larger aperture to mitigate it.
Solution Approach 2:
The system changes the angular distribution parameter of the incident light by switching between different light emission regions. By varying this parameter temporally, the system achieves speckle reduction through parameter modulation rather than through geometric enlargement of the optical components.
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 approach effectively reduces speckle visibility without increasing the size or cost of the projection system, maintaining image quality and brightness while minimizing the need for larger lenses.
Implementation Method 1
Speckle is a pattern in which bright points and dark points are distributed in a striped pattern or a spotted pattern due to interference of light
Data Source
AI summary
An illumination device includes a light source device which has a plurality of light emission regions including a first light emission region and a second light emission region, and is able to adjust the amount of light emitted from each of the plurality of light emission regions, a light source control device which controls the light source device such that, in a first period, the amount of light emitted from the first light emission region is different from the amount of light emitted from other light emission regions among the plurality of light emission regions, and in a second period, the amount of light emitted from the second light emission region is different from the amount of light emitted from the second light emission region in the first period, and an illumination optical system which superimposes light from the plurality of light emission regions in an illumination region.