Micromechanical Mirror Position Detection via Optical Reflection
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Solution Overview
Problem
Existing micromechanical components for optical beam deflection, such as projectors and scanners, face challenges in accurately determining the instantaneous position of a mirror with respect to a frame without interfering with the mirror's adjustability and introducing mechanical or electrical issues due to the use of piezoresistive elements and electrical feeder lines.
Innovation Solution
The solution involves using an optical sensor to determine the reflection position of a light beam on an internal surface within the micromechanical component, which is not affected by the mirror's adjustment, allowing for precise positioning without electrical feeder lines over torsion springs, and incorporating a control unit to adjust the mirror based on light beam blocking signals for safety and brightness calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoresistive elements with electrical feeder lines are used to determine mirror position, then position information is obtainable, but the feeder lines affect the flexural and torsional rigidity of the springs, negatively impacting mirror adjustability
Solution Approach 1:
The invention extracts the measurement function from the mechanical structure by using the light beam itself as the measurement carrier. The reflection position of the light beam on the detection surface directly indicates the mirror position without requiring additional electrical feeder lines, thereby eliminating the conflict between measurement and mechanical properties.
Solution Approach 2:
The invention replaces the electrical measurement system (piezoresistive elements and feeder lines) with an optical measurement system. The light beam serves as the information carrier to detect mirror position, substituting mechanical-electrical coupling with optical coupling that does not affect the mechanical properties of the torsion springs.
2Measurement precision
If electrical feeder lines are guided over torsion springs to connect piezoresistive elements, then position data can be read, but the feeder lines are subject to mechanical destruction due to spring deformation
Solution Approach 1:
The invention replaces electrical signal transmission through mechanically stressed feeder lines with optical signal transmission through a light beam. The light beam reflects off the mirror and its reflection position on the detection surface provides position information without being subjected to mechanical deformation, thereby ensuring reliability.
Solution Approach 2:
The invention introduces a light beam as an intermediary between the mirror and the detection surface. This intermediary carries position information optically without requiring direct physical or electrical connection through the deformable spring structure, eliminating the reliability issue of feeder lines.
3Measurement precision
If narrow electrical feeder lines are used to guide signals over torsion springs, then position information can be transmitted, but the lines require complex shielding and manufacturing
Solution Approach 1:
The invention substitutes electrical signal transmission through narrow, difficult-to-manufacture feeder lines with optical transmission using a light beam. The light beam requires no shielding, routing, or complex manufacturing, as it naturally traverses the optical path from the mirror to the detection surface without interference from surrounding structures.
4Measurement precision
If capacitance-based sensors are used to determine mirror position, then position information is obtainable, but the signal is low and susceptible to interference, resulting in inaccurate positioning
Solution Approach 1:
The invention replaces capacitance-based electrical sensing with optical sensing. The light beam's reflection position on the detection surface provides a high-contrast, interference-resistant signal that directly indicates mirror position, eliminating the signal quality issues inherent in capacitance measurement.
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 enables accurate and interference-free determination of the mirror's position and light intensity, reducing mechanical and electrical interference, enhancing the adjustability and safety of the micromechanical component, and allowing for self-test and brightness calibration functions.
Implementation Method 1
a light window at whose interfaces the emerging light beam is partially reflected and deflected as a reflected beam into the interior of the micromechanical component
Data Source
AI summary
A micromechanical component has a light window; a mirror element adjustable with respect to the light window from a first position into at least one second position about at least one axis of rotation, an optical sensor having a detection surface designed to ascertain a light intensity on the detection surface and to provide a corresponding sensor signal. The light window, the mirror element in the first position and the detection surface are situated in relation to one another in such a way that a portion of a light beam reflected on the light window strikes the detection surface at least partially; and an evaluation unit designed to define, on the basis of the sensor signal, information regarding an instantaneous position of the mirror element and/or an instantaneous intensity of the deflected light beam.