Load Sensor Package Structure for High-Load Accuracy
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Solution Overview
Problem
Conventional load sensors are expensive due to high manufacturing costs for high load applications and suffer from sensitivity variations caused by environmental effects and material mismatches, leading to measurement errors.
Innovation Solution
A load sensor package design utilizing vertical and planar piezoresistivity effects, with a housing that transfers a predetermined fraction of the applied load to a stress sensor, allowing a smaller sensor to measure larger loads, and incorporating Wheatstone bridges to accurately measure stress by differentiating between plane and three-dimensional stress components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional load sensors are used for high load applications, then the sensor size increases, but manufacturing costs increase rendering the product too expensive
Solution Approach 1:
The housing is divided into a cap, column, peripheral structure, and base, with the stress sensor mounted on the base. The load transfer path is segmented between the column (transfering predetermined fraction) and peripheral structure (transfering remaining fraction), allowing the sensor to measure only a fraction of the total load, thus reducing sensor size and cost while maintaining high load capacity
Solution Approach 2:
The stress sensor acts as an intermediary element that measures a fraction of the load rather than the full load. The column and peripheral structure serve as mechanical intermediaries that distribute and transfer specific portions of the load to the sensor, enabling cost-effective measurement of high loads without requiring a proportionally large and expensive sensor
2Reliability
If conventional load sensors are used, then sensitivity variations occur due to environmental effects and material mismatches, but measurement accuracy deteriorates
Solution Approach 1:
The stress sensor is strategically positioned on the base where it experiences controlled stress conditions. The column and peripheral structure are designed with specific geometric properties that create a predictable stress distribution, ensuring the sensor operates in an optimal local region with stable mechanical properties independent of environmental variations
Solution Approach 2:
The design changes the stress state parameters by transferring only a predetermined fraction of the load to the sensor through the column, rather than exposing the sensor to the full load. This parameter change in load distribution reduces the impact of environmental effects and material mismatches on measurement accuracy
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 improves stress measurement accuracy and sensitivity, enabling the measurement of a wide range of loads with reduced sensor size and cost, while minimizing errors from environmental and material mismatch effects.
Implementation Method 1
The load sensor is configured to measure stress by observing the piezoresistive effects of a semiconductor material
Implementation Method 2
incorporating Wheatstone bridges to accurately measure stress by differentiating between plane and three-dimensional stress components
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
A load sensor package (140) includes a housing having a cap (142), a column (144), a peripheral structure (146), and a base (148). The base (148) includes a major surface configured to mount a stress sensor (120), while the cap (142) includes a cap major surface configured to receive a load to be measured. The column (144) is configured to transfer a predetermined fraction of the load to be measured to the base through the stress sensor (120). The peripheral structure (146) is configured to transfer the remaining fraction of the load to be measured to the base.