Gyro Sensor Movable Portion Sticking Prevention
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Solution Overview
Problem
Existing gyro sensors face issues with the movable portion sticking to the substrate due to excessive electrostatic force, which exceeds the recovery force of the beam portion, leading to inaccurate angular velocity detection.
Innovation Solution
The design incorporates an elastically deformable beam portion that supports the movable portion, ensuring it remains displaced within a range where the recovery force is greater than the electrostatic force, with a movable critical point positioned to prevent sticking, and features like protruding portions and concavities on the substrate to reduce contact area and enhance displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the movable portion is greatly displaced to the electrode side to increase detection sensitivity, then the electrostatic force becomes larger than the recovery force of the beam portion, but the movable portion sticks to the electrode
Solution Approach 1:
The patent introduces a repulsive electrostatic force as a preliminary counteraction to prevent the movable portion from sticking to the substrate. By applying a voltage that generates repulsive force between like-charged surfaces (movable portion and substrate), the system preemptively counteracts the harmful attractive electrostatic force before sticking occurs, allowing the movable portion to be displaced closer to the substrate without adhesion.
Solution Approach 2:
The patent changes the electrical parameter (voltage polarity and magnitude) to transform the electrostatic interaction from attractive to repulsive. By controlling the voltage applied to the movable portion or substrate, the system dynamically adjusts the electrostatic force parameter to prevent sticking while maintaining detection sensitivity.
2Length of moving object
If the movable portion is kept close to the substrate to reduce displacement range, then the electrostatic force increases, but the recovery force must remain larger to prevent sticking
Solution Approach 1:
The repulsive electrostatic force is applied in advance to counterbalance the attractive electrostatic force that increases when the movable portion is close to the substrate. This preliminary counteraction allows the system to maintain a small displacement range while managing the increased electrostatic force through active compensation.
3Stability of the object's composition
If the movable portion contacts the substrate to stop displacement, then the contact area increases, but sticking is more likely to occur
Solution Approach 1:
The repulsive electrostatic force prevents actual contact between the movable portion and substrate by counteracting the attractive force before contact occurs. This eliminates the harmful contact area while maintaining displacement control through the balanced electrostatic forces.
Solution Approach 2:
The patent replaces the mechanical contact-based displacement stop with an electrostatic field-based control mechanism. Instead of relying on physical contact to limit displacement, the system uses controlled electrostatic repulsion to prevent contact, thereby avoiding the sticking issue associated with mechanical contact.
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 configuration effectively reduces sticking of the movable portion to the substrate, allowing for reliable detection of angular velocity and other physical quantities like acceleration, enhancing the sensor's reliability and accuracy.
Implementation Method 1
an elastically deformable beam portion which displaceably supports the movable portion
Implementation Method 2
electrostatic capacitor which is formed between the movable portion and the electrode is changed, it is possible to detect angular velocity that is applied to the gyro sensor based on the change in electrostatic capacitor
Implementation Method 3
the movable portion torsionally deforms the beam portion by Coriolis force when angular velocity is applied about an X axis in a state in which the mass portion is vibrated in a Y axis direction
Data Source
AI summary
An oscillator includes a substrate, a detection flap plate which is disposed facing the substrate, and an elastically deformable beam portion which displaceably supports the detection flap plate in a Z axis direction with respect to the substrate, in which the detection flap plate is displaced to the substrate side in a range in which recovery force of the beam portion is larger than the electrostatic force which is formed between the substrate and the detection flap plate. That is, when a boundary at which electrostatic force and recovery force are equal is a pull in critical point, the detection flap plate is displaced within a region above the pull in critical point.