Rotary Diffuser Speckle Noise Reduction in Projector Illumination
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Solution Overview
Problem
Existing illumination devices for projectors, which use a diffuser plate to reduce speckle noise, are insufficient in effectively eliminating this issue, leading to a need for further improvement in reducing speckle noise in projection images.
Innovation Solution
An illumination device comprising a first light source, a second light source, a light combining member, a rotary diffusion device with a substrate having different uneven structures on its diffusing surface, and a collimator, where the substrate rotates to temporally change the speckle pattern, reducing noise by averaging it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transmissive diffuser plate is used to reduce speckle noise, then some speckle reduction effect is achieved, but the speckle noise cannot be sufficiently reduced
Solution Approach 1:
The patent employs a rotary diffusion device that rotates the diffuser plate at high speed, dynamically changing the diffusion pattern over time. This temporal variation in the diffusion process effectively reduces speckle noise by averaging multiple speckle patterns, transforming a static insufficient solution into a dynamic effective one.
Solution Approach 2:
The diffuser plate is divided into multiple areas (first area, second area, etc.) with different uneven structures. Each area has distinct surface characteristics that create different diffusion patterns. By segmenting the diffuser plate into functionally different regions, the system generates diverse speckle patterns that when averaged through rotation, provide superior speckle reduction compared to a uniform diffuser.
2Illumination intensity
If multiple light sources with different wavelength bands are combined, then color gamut and efficiency are improved, but speckle noise becomes more prominent
Solution Approach 1:
The rotary diffusion device dynamically modulates the combined light from multiple wavelength bands. By rotating the diffuser with multiple uneven structure areas, each wavelength band's speckle pattern is temporally varied and averaged, reducing the overall speckle noise while preserving the benefits of multi-wavelength light combining for color gamut and efficiency.
Solution Approach 2:
Different areas of the diffuser plate have different uneven structures optimized for different aspects of light diffusion. The first area, second area, and other regions have distinct surface characteristics that collectively address the speckle reduction challenge across multiple wavelength bands, with each area contributing specific local diffusion properties.
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 noise in projector images by temporally averaging the speckle pattern through the use of a rotary diffusion device with a substrate featuring distinct uneven structures, resulting in improved image quality.
Implementation Method 1
a condenser which is disposed between the light combining member and the rotary diffusion device, and which condense the illumination light emitted from the light combining member toward the rotary diffusion device
Implementation Method 2
a diffusing surface configured to diffusely reflect the illumination light emitted from the light combining member
Implementation Method 3
a collimator configured to collimate diffusion light of the illumination light emitted from the rotary diffusion device
Data Source
AI summary
An illumination device includes a first light source configured to emit first light, a second light source configured to emit second light, a light combining member configured to combine the first light and the second light with each other to emit illumination light, a rotary diffusion device having a substrate including a diffusing surface configured to diffusely reflect the illumination light, and a driver configured to rotate the substrate centering on a rotational axis, a condenser disposed between the light combining member and the rotary diffusion device, and configured to condense the illumination light toward the rotary diffusion device, and a collimator configured to collimate diffusion light of the illumination light. The diffusing surface of the substrate includes a first area where a first uneven structure is disposed, and a second area where a second uneven structure different from the first uneven structure is disposed.