Latched MEMS Comb Actuator for Higher Electrostatic Drive Force
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Solution Overview
Problem
Microelectromechanical systems (MEMS) face limitations in driving power due to the spacing constraints imposed by etching techniques, which restrict the minimum spacing between comb fingers, affecting the intensity of electrostatic forces and overall performance.
Innovation Solution
A microelectromechanical system with a latching mechanism that allows the comb fingers to be initially spaced wider than the minimum required, enabling etching, and then engages them closer for enhanced electrostatic force generation, comprising a movable and fixed comb with a latching mechanism that adjusts the spacing between the fingers to increase driving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the spacing between comb fingers is reduced to increase electrostatic force intensity, then driving power is improved, but manufacturing precision deteriorates due to etching technique constraints
Solution Approach 1:
The patent applies preliminary action by first manufacturing the combs with sufficient spacing during etching, then subsequently bringing them into engagement through a controlled mechanism. This allows the etching process to work with relaxed spacing constraints while the final operational configuration achieves the desired close spacing for high electrostatic force.
Solution Approach 2:
The patent employs dynamics by making the spacing between combs variable - initially large during manufacturing, then reducible to a small operational spacing. This dynamic adjustment resolves the contradiction by allowing different spacing requirements at different stages of the device lifecycle.
2Manufacturing precision
If the spacing between comb fingers is increased to satisfy etching constraints, then manufacturing precision is improved, but driving power deteriorates due to reduced electrostatic force intensity
Solution Approach 1:
The patent uses preliminary action by establishing the combs in a manufacturable state with adequate spacing, then subsequently transitioning them to the high-power operational state with reduced spacing. This separates the manufacturing constraint satisfaction from the operational performance optimization.
Solution Approach 2:
The patent applies dynamics by enabling the comb spacing to change from a large initial value (for manufacturing) to a small operational value (for power). This dynamic transformation allows both manufacturing precision and driving power requirements to be satisfied at different times.
3Power
If a latching mechanism is added to engage comb fingers, then driving power is improved through reduced spacing, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary mechanism (the latching element) that mediates between the two combs, enabling them to engage at close spacing. This intermediary component facilitates the high-power configuration while managing the complexity through a dedicated engagement function.
Solution Approach 2:
The latching mechanism performs preliminary action by securing the combs in their engaged position, allowing them to maintain the close spacing necessary for high electrostatic force throughout operation, rather than requiring continuous active control.
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 system achieves increased driving power by reducing the spacing between comb fingers, overcoming the constraints of etching techniques and enhancing the performance of MEMS devices like toothed wheel drivers.
Implementation Method 1
the intensity of the electrostatic forces generated by the interdigitated combs is inversely proportional to the spacing between the fingers of the fixed combs and the fingers of the movable combs
Implementation Method 2
during the disengagement phase, the drive tooth is moved in the opposite direction, as a result of elastic return forces generated by the suspensions of the interdigitated combs
Data Source
AI summary
The invention relates to a microelectromechanical system comprising a support and an actuator, the actuator comprising a drive module comprising:a fixed drive portion (210), mounted fixedly on the support, and comprising a fixed comb (211 with fingers (213), anda movable drive portion (220), mounted movably relative to the support, and comprising a movable comb (221) with fingers (223),a latching mechanism that is movable between an initial unlatched configuration and a final latched configuration,wherein the movable comb (221) is arranged facing the fixed comb (211) so that when the latching mechanism is in the initial unlatched configuration, the fingers (223) of the movable comb (221) are not engaged between the fingers (213) of the fixed comb (211), and when the latching mechanism is in the final latched configuration, the fingers (223) of the movable comb (221) are engaged between the fingers (213) of the fixed comb (211) and the latching mechanism (500) prevent disengagement of the fingers (223) of the movable comb (221) from between the fingers (213) of the fixed comb (211).