MEMS Micromotor Drive Module Asymmetric Pinion Layout
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Solution Overview
Problem
Existing drive modules for clockwork mechanisms face challenges in optimizing silicon surface usage and achieving high efficiency due to the rectangular shape of silicon chips and circular rotors, leading to large unused silicon areas and inefficient actuator arrangement.
Innovation Solution
A drive module design featuring a pinion coaxial with the rotor, arranged above the rotor with a meshing zone near the outer peripheral edge, and actuators with symmetrical parts and angularly offset pawls to minimize silicon usage and enhance efficiency, along with a manufacturing method involving etched silicon plates nested in a wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rectangular silicon chips are used to maximize parts per wafer, then manufacturing efficiency is improved, but the circular rotor shape creates large unused silicon areas reducing area utilization
Solution Approach 1:
The patent introduces a pinion component that is asymmetrically positioned relative to the circular rotor, with its meshing zone located closer to one edge of the rectangular silicon chip. This asymmetric arrangement allows the circular rotor and rectangular chip to coexist with minimized wasted space, as the pinion fills the gap between the circular rotor and the rectangular chip boundary.
2Force
If actuators are made large to generate sufficient force, then driving capability is improved, but the required silicon area increases reducing overall efficiency
Solution Approach 1:
The patent employs a three-dimensional rotor structure with elevated mass elements positioned above the silicon plate plane, rather than relying solely on increased actuator area. This vertical dimensionality allows the actuators to generate sufficient torque through the elevated mass distribution, reducing the required actuator area on the silicon surface.
Solution Approach 2:
The rotor is constructed with composite structure combining the silicon plate substrate with elevated mass elements, creating a composite rotational component. This composite design concentrates mass in strategic locations to maximize moment of inertia and driving force while minimizing the overall area occupied by the rotor and actuators on the silicon chip.
3Ease of operation
If the pinion diameter is increased to cantilever beyond the plate edge for meshing, then meshing capability is improved, but the distance from rotor edge to plate edge must be minimized increasing complexity
Solution Approach 1:
The patent implements a nested spatial arrangement where the pinion is positioned within the boundary defined by the rotor and plate edge, with the pinion's meshing zone extending to the plate edge. The rotor, pinion, and plate edges are nested concentrically and radially, allowing the pinion to cantilever effectively while maintaining compact overall dimensions and simplified manufacturing.
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 design optimizes silicon surface usage, increases the efficiency of the micromotor, and allows for modular adaptation to varying loads and assembly configurations, improving the overall performance and modularity of the drive module.
Implementation Method 1
using electrostatic actuators with interdigitated combs or 'comb drive'
Implementation Method 2
the stylus being provided at its free end with a pawl provided to cooperate with a serrated toothing provided on the outer peripheral edge of the rotor with a view to drive it in rotation sequentially
Implementation Method 3
as they must generate large forces
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The module (13) has a plate (30) e.g. silicon wafer, of crystalline material with an upper layer in which a micro electromechanical system type micro motor (36) is engraved, where the module is in V-shape. A pinion is connected to a rotor (42), and is meshed with a wheel in a mesh area (70) situated close to a peripheral edge (72) of the plate. The rotor is arranged on the plate so as to minimize a distance between a peripheral edge of the rotor and the edge (72). Diameter of the pinion is higher than that of the rotor so as to be in cantilever relative to the plate in the area. An independent claim is also included for a method for fabricating a driving module.