Linear MEMS Mirror Variable Resolution Scanning Control
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Solution Overview
Problem
Existing MEMS devices with linear mirrors face limitations in varying resolution and light intensity, leading to slow refresh rates and insufficient maximum resolution, particularly when trying to focus on specific areas of interest.
Innovation Solution
A MEMS device with linear actuation operating below its natural resonance frequency, allowing for different scanning speeds in various areas by introducing a DC offset in the driving moment to control the scanning angle, enabling 'zooming-in' and 'zooming-out' without activating resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If linear MEMS mirrors operate at constant scanning speed, then the device structure is simple, but the resolution and light intensity cannot be varied in different areas
Solution Approach 1:
The patent applies dynamics by transitioning from constant-speed scanning to variable-speed scanning. The mirror scanning speed is dynamically adjusted according to a control signal that varies the angular position over time, enabling different dwell times in different scanning zones. This allows high resolution in areas of interest (slower scanning) and faster scanning in less important areas, achieving adaptability without adding mechanical complexity.
Solution Approach 2:
The patent changes the temporal parameter of the driving signal (DC offset component) to control the mirror's angular position and scanning speed. By adjusting the DC offset in the driving voltage, the system varies the scanning speed and dwell time in different zones, thereby controlling resolution and light intensity distribution without mechanical adjustments.
2Manufacturing precision
If DC offset is introduced to control scanning angle, then resolution and light intensity can be varied, but the scanning pattern becomes more complex
Solution Approach 1:
The patent employs feedback by using a position sensor to detect the actual angular position of the mirror and comparing it with the desired position. The control signal (including DC offset) is adjusted based on this feedback to achieve precise position control, ensuring accurate resolution and light intensity variation while simplifying operation through automated closed-loop control.
3Productivity
If scanning speed is increased to improve refresh rate, then productivity increases, but resolution in areas of interest decreases
Solution Approach 1:
The patent applies local quality by implementing non-uniform scanning speed distribution across different spatial zones. In areas of interest, the scanning speed is reduced (higher dwell time) to achieve high resolution, while in less important areas, the scanning speed is increased. This local optimization allows the system to maintain high overall refresh rate while achieving high resolution where needed, resolving the contradiction between productivity and measurement precision.
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 allows for flexible control of scanning speed and resolution in different areas, enhancing detail in areas of interest without the need for mechanical or optical adjustments, achieving efficient and electronic variation of light intensity and resolution.
Implementation Method 1
The micro-mirror 5 has a purely electrostatic actuation and is made in a chip 17 forming a platform 11. The platform 11 has a reflecting surface (not shown) and is supported by a suspended frame 13 through a first pair of arms 12 (first torsional springs). The first arms 12 extend from opposite sides of the platform 11 and allow twisting of the platform 11 around first rotation axis A.
Implementation Method 2
Each actuation group 18A, 18B here comprises first electrodes 19 facing respective second electrodes 20. By applying a voltage drop between the first electrodes 19 and the second electrodes 20, attraction/repulsion forces are generated between them, causing a torque (moment) on the springs and rotation of the arms 12, 16 around their respective axes A, B.
Data Source
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AI summary
The method for controlling an angular position of a MEMS mirror includes: applying a first driving moment to the MEMS mirror to generate a rotational scanning movement of the mirror; and, at a zooming instant, applying a second driving moment to the MEMS mirror, wherein the second driving moment is equal to the first driving moment plus an extra moment. The extra moment may be a DC offset. After a transient period of time from zooming instant, a third driving moment M2 = kθ̇2t is applied. The first and third driving moment are variable linearly with time. The driving moments are applied to torsional springs of the mirror.