Semiconductor Acceleration Sensor L-Shaped Beam Stopper Design
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Solution Overview
Problem
Semiconductor acceleration sensors face challenges in limiting the movement range of a weight part in the horizontal direction, leading to excessive stress on beam parts and potential breakage, especially when side impacts occur, as existing stopper designs are difficult to implement effectively.
Innovation Solution
The semiconductor acceleration sensor incorporates L-shaped beam parts with protruding and receiving recessed portions to limit horizontal movement of the weight part, and alternative designs featuring a stopper or a rectangular frame-shaped stopper to enclose the weight part's bottom portion, preventing excessive stress on the beam parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beam parts are made as thin as possible to allow smooth movement of the weight part, then the sensitivity and movement smoothness are improved, but the beam parts become more prone to breakage when the weight part suddenly moves or moves beyond normal range
Solution Approach 1:
The patent introduces stoppers formed at upper and lower positions in the space for the weight part to move. These stoppers prevent the weight part from moving beyond predetermined amounts in the up and down direction, thereby preventing excessive stress on the beam parts and avoiding breakage while maintaining thin beam design for high sensitivity
2Reliability
If stoppers are formed to limit the movement of the weight part in the up and down direction, then the beam part breakage is prevented, but the structure becomes more complex
Solution Approach 1:
The patent combines the stopper function with the existing space structure for the weight part. The stoppers are formed at upper and lower positions within the space that is already required for weight part movement, merging the protection function into the existing structural framework rather than adding completely separate protective elements
3Measurement precision
If the length of beam parts is elongated to increase the sensitivity of the acceleration sensor, then the acceleration detection capability is improved, but the beam parts become more vulnerable to breakage from side impacts
Solution Approach 1:
The patent forms stoppers at upper and lower positions to limit the movement range of the weight part in the up and down direction. This prevents excessive movement that could cause breakage of the elongated beam parts when side impacts occur, thereby protecting the sensitive beam structure while maintaining its elongated design for high sensitivity
4Device complexity
If a simple stopper is used to limit horizontal movement of the weight part, then the structure remains simple, but the stopper cannot effectively limit movement in all directions
Solution Approach 1:
The patent divides the movement limitation function into multiple stoppers positioned at different locations (upper and lower positions) within the space. Each stopper handles movement limitation in specific directions, and collectively they provide comprehensive restriction of weight part movement in all horizontal directions while keeping each individual stopper structure simple
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
These designs effectively limit the weight part's horizontal movement, preventing beam part breakage and ensuring continuous acceleration measurement even under side impacts, while also improving impact resistance properties to reduce the risk of damage.
Implementation Method 1
detects the acceleration by using a movement of the weight part in the direction of the acceleration caused by bending of the beam parts
Implementation Method 2
the protruding portion contacts an inner wall surface of the receiving recessed portion so as to limit horizontal movement of the weight part
Data Source
AI summary
A semiconductor acceleration sensor having beam parts formed in substantially L-shape to surround a weight part, wherein formed to surround a square part, as seen in plan view and constituting the weight part, are two elongated L-shaped beam parts, at locations close to proximal end portions of which are formed protruding portions protruding from a fixed part toward the weight part, and receiving recessed portions protruding from the weight part toward the fixed part to surround the protruding portions. The protruding portions have an outer shape substantially the same as an inner wall surface of the receiving recessed portions so that movements of the weight part in any directions in a horizontal direction perpendicular to an up and down direction are limited as a result of reception of the protruding portions by the receiving recessed portions. Thus, even when a side impact is applied to the acceleration sensor, the weight part is prevented from moving significantly, thereby preventing an excessive stress from being applied to the beam parts to break the beam parts.