Piezoelectric Sensor Alignment via Resin Intermediary and Seam Welding
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Solution Overview
Problem
Existing force sensors using piezoelectric materials face issues with dimensional differences leading to weld irregularities, moisture leakage, and reliability problems due to misalignment and creep phenomena, which affect stable force detection over time.
Innovation Solution
A sensor device design featuring a package with a recessed section and a lid that aligns via hollow portions with the sensor element, ensuring precise alignment and direct contact without adhesives, thereby preventing misalignment and creep, and maintaining airtight sealing through seam welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sensor element is welded to the metal ring, then the individual parts are joined together, but dimensional differences cause irregularities at the welded portion, possibly generating gaps and allowing moisture entry
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the sensor element and the metal ring. This resin layer compensates for dimensional differences and irregularities that would otherwise prevent proper contact or create gaps, thereby maintaining both joint strength and sealing reliability without requiring perfect welding alignment
Solution Approach 2:
The patent replaces the mechanical welding connection with a chemical bonding system using resin. This substitution eliminates the sensitivity to dimensional tolerances and alignment irregularities inherent in welding, while providing both structural support and moisture sealing functions
2Ease of manufacture
If the contact surface height and joining surface height do not coincide, then manufacturing flexibility is maintained, but misalignment occurs causing insufficient joining area and reduced stress resistance
Solution Approach 1:
The resin layer acts as a compensatory intermediary that fills the height difference between the contact surface and joining surface. This allows the surfaces to be at different heights while still achieving full contact and maximum joining area, maintaining both manufacturing flexibility and stress resistance
Solution Approach 2:
The patent changes the physical state and properties of the bonding medium by using a deformable resin material instead of rigid mechanical connection. This allows the bonding interface to adapt to height variations through material deformation, maintaining optimal contact area regardless of surface height differences
3Manufacturing precision
If adhesive is used to bond the contact surface, then misalignment is prevented, but creep phenomenon occurs causing long-term reduction in thickness and applied pressure
Solution Approach 1:
The patent selects resin materials with specific viscoelastic parameters that balance initial bonding precision with long-term dimensional stability. By carefully controlling the resin's mechanical properties (viscosity, modulus, creep resistance), the system achieves both precise alignment and resistance to thickness reduction over time
Solution Approach 2:
The patent uses composite material properties by combining the rigidity of the sensor element and metal ring with the viscoelastic characteristics of the resin layer. This composite structure leverages the strengths of each material: the rigid components provide structural stability while the resin provides alignment tolerance and creep resistance
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
The design stabilizes detection characteristics over a long period by preventing misalignment and creep, ensuring reliable and consistent force detection without leakage, even under repeated pressure applications.
Implementation Method 1
The quartz plates 216 output (induce) electric charge accompanying this applied force, in the detection electrode 218 by a piezoelectric effect
Data Source
AI summary
A package having a recessed section, a sensor element arranged in the recessed section and having a piezoelectric material, a lid joined to the package and sealing the recessed section of the package are provided. The package has a first hollow portion which a part of the sensor element fits with, on an inner bottom surface of the recessed section. The lid has a second hollow portion which a part of the sensor element fits with.