Micromirror Coating for Artefact Pixel Suppression
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Solution Overview
Problem
Conventional mirror devices suffer from the occurrence of visible artefact pixels due to undesired reflections at the cover element, which degrade image quality without providing adequate protection for the micromirror.
Innovation Solution
A mirror device design with a coating on the micromirror's reflective surface that has a high reflection coefficient for specific angles, preventing artefact reflections while ensuring desired beam deflection, and a cover element inclined at a specific angle to keep the micromirror protected and contamination-free.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover element is placed in front of the micromirror for protection, then the micromirror is protected from dirt or damage, but visible artefact pixels occur due to undesired reflections at the cover element
Solution Approach 1:
The coating on the micromirror surface is designed with spatially varying optical properties - it has different reflection coefficients for different incident angle ranges. This local differentiation in reflective behavior allows the system to protect the micromirror while controlling where reflected light goes, preventing artefact pixels in certain viewing zones.
Solution Approach 2:
The invention changes the optical parameters of the micromirror surface by applying a coating with specific reflection characteristics. The coating modifies how light interacts with the micromirror surface, creating angle-dependent reflection behavior that suppresses artefact pixels while maintaining protective coverage.
2Reliability
If the cover element is aligned at an incline with respect to the micromirror, then the micromirror remains protected, but reflection beams impinge on the micromirror at angles that cause artefact pixels
Solution Approach 1:
The coating applies different reflective properties to different regions/angles of the micromirror surface. Areas receiving reflection beams are specifically designed to have low reflection coefficients for those angles, preventing artefact beam generation while maintaining protection.
Solution Approach 2:
The invention converts the potentially harmful reflection beams into beneficial or harmless paths by using the coating to redirect them. The reflection beams that would normally create artefacts are now directed toward regions where they don't cause visible defects, transforming a harmful optical path into an acceptable one.
3Object-affected harmful factors
If the reflective surface of the micromirror is reduced in extension to prevent artefact reflections, then artefact pixels are reduced, but the design freedom is restricted
Solution Approach 1:
Instead of changing the geometric parameter of micromirror size, the invention changes the optical parameter of the surface through coating. This allows full micromirror extension to be maintained while controlling reflection behavior through material properties rather than geometric constraints.
Solution Approach 2:
The coating creates local variations in reflective properties across the micromirror surface, allowing different zones to have different optical characteristics. This enables the full surface area to be utilized while specific zones suppress artefact reflections, maintaining both design freedom and image quality.
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 significantly improves image quality by minimizing artefact pixels, maintaining micromirror protection, and allowing for cost-effective design modifications without restricting design freedom, resulting in robust and high-quality image projection.
Implementation Method 1
a beam of light (58) impinging upon a reflective surface (54) is deflected in the direction of cover element (52) due to its reflection at reflective surface (54)
Implementation Method 2
a beam of light (58) emitted by a light source (56) or by an external light source impinges through cover element (52) upon reflective surface (54)
Data Source
AI summary
A mirror device including a micromirror, which is excitable to an oscillatory motion such that a first impingement angle of a beam of light impinging upon its reflective surface varies within a first value range, and a cover element, which is stationary so that, due to the reflection at the reflective surface, the beam impinges upon at least one inner surface of the cover element and partially impinges as reflection beam upon the reflective surface. The cover element is aligned at an incline relative to a neutral position of the micromirror such that a second impingement angle of the reflection beam impinging upon the micromirror lies within a second value range outside the first value range. The reflective surface has a coating, which has a reflection coefficient of at least 0.6 for the first value range and a reflection coefficient of maximally 0.4 for the second value range.