MEMS Gyro Sensor Projections for Adhesion Prevention
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Solution Overview
Problem
Gyro sensors face damage and adhesion issues due to collisions and excessive voltage, particularly in MEMS capacitance gyro sensors, where electrodes can attract and adhere to each other, making size reduction difficult and increasing the risk of damage.
Innovation Solution
The design incorporates projections on the driving mass and islands with distance regulating portions to maintain a controlled distance, ensuring the driving mass oscillates without contacting the fixed electrode, and projections on the detection mass to prevent adhesion, allowing for shock absorption and maintaining designed oscillation amplitude without the need for electrode projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If projections are formed on electrodes to prevent adhesion, then adhesion between electrodes is reduced, but the distance between electrodes must be increased which makes size reduction difficult
Solution Approach 1:
The projection is divided into multiple segment structures (first projection and second projection) with different heights and positions. The first projection has height h1 and the second projection has height h2, creating a segmented profile that provides adhesion prevention while minimizing the overall distance increase required between electrodes.
Solution Approach 2:
Different regions of the electrode structure have different projection characteristics. The first projection is positioned at a first position with height h1, while the second projection is positioned at a second position with height h2. This local differentiation allows adhesion prevention at critical locations without uniformly increasing the entire electrode spacing.
2Device complexity
If the driving system is positioned to surround the detecting system, then the structure is compact, but collision damage risk increases when excessive voltage is applied or the sensor drops
Solution Approach 1:
Projections are provided on the driving mass and/or first island beforehand as protective structures. When excessive voltage is applied or the sensor drops, these pre-positioned projections act as cushioning elements that collide with the driving mass first, absorbing the impact energy and preventing direct collision damage to the detecting system and other critical components.
3Measurement precision
If two driving systems are arranged side by side to cancel acceleration components, then angular velocity detection accuracy is improved, but the risk of collision between driving systems increases
Solution Approach 1:
Projections are provided on the driving masses and islands of both driving systems as protective measures. When the two driving systems oscillate in opposite directions and collision risk arises, these pre-positioned projections act as buffer elements that absorb impact energy, preventing direct collision between the driving systems while maintaining the side-by-side arrangement necessary for accurate angular velocity detection.
4Reliability
If the minimum distance between driving mass and first island is increased to prevent contact, then adhesion is prevented, but the driving amplitude is reduced
Solution Approach 1:
The projection structure is segmented into multiple portions with different heights (h1 and h2). This segmentation allows the minimum distance to be increased sufficiently to prevent adhesion at the critical points where projections contact the driving mass, while the varied heights ensure that the overall driving amplitude remains within the designed range by providing progressive protection rather than a single uniform barrier.
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 effectively prevents damage and adhesion by controlling the distance between components, reducing shock impact, and maintaining the designed oscillation amplitude, while avoiding the necessity for electrode projections, thus enhancing the reliability and sensitivity of gyro sensors in electronic devices.
Implementation Method 1
a driving unit (22) connected with the driving mass (20), and driving the driving mass (20) in a first direction (x-axis direction). The driving unit (22) includes a movable electrode unit (24) connected with the driving mass (20), and a fixed electrode unit (26) disposed opposed to the movable electrode unit (24)
Implementation Method 2
a projection (44) provided at least either on the surface of the driving mass (20) opposed to the first island (40), or on the surface of the first island (40) opposed to the driving mass (20)... reducing shock impact
Implementation Method 3
An MEMS (micro electro mechanical system) capacitance gyro sensor includes a driving system and a detecting system, and determines an angular velocity based on a Coriolis force generated in the detecting system when an angular velocity is applied to the driving system oscillating at a constant oscillation frequency
Implementation Method 4
determines an angular velocity based on a Coriolis force generated in the detecting system when an angular velocity is applied to the driving system oscillating at a constant oscillation frequency and to the detecting system interlocked with the driving system, regarding this force as a change of the capacitances of the detecting system (movable electrode) and a fixed electrode
Data Source
AI summary
A gyro sensor includes: a driving mass; a detection mass connected with the driving mass; a driving connection one end and the other end of which are connected with the driving mass and an anchor, respectively; an island connected with the anchor, and disposed with a clearance left between the island and the driving mass in such a manner as to be electrically connected with the driving mass; and a projection provided at least either on the surface of the driving mass opposed to the island, or on the surface of the island opposed to the driving mass. The driving unit includes a movable electrode unit connected with the driving mass, and a fixed electrode unit. The minimum distance between the driving mass and the island is longer than the driving amplitude of the driving mass and shorter than the maximum amplitude of the movable electrode unit.