Plate-Shaped Force Sensor with Controlled-Modulus Adhesive Bonding
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Solution Overview
Problem
Existing electronic devices struggle to accurately detect the magnitude of a force applied to a plate-shaped member due to the occurrence of a NULL point in the detection signal, which is caused by varying elastic moduli of the adhesive members and uneven deformation of the piezoelectric film.
Innovation Solution
The electronic device incorporates a first adhesive member with a storage elastic modulus of 1 MPa to 20 MPa, ensuring consistent deformation and accurate detection of force by preventing the NULL point, while also providing waterproofness and impact absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive members with varying elastic moduli are used to fix the plate-shaped member, then the plate-shaped member can be fixed to the housing, but the detection signal exhibits a NULL point due to uneven deformation of the piezoelectric film
Solution Approach 1:
The patent applies parameter changes by specifying a precise range for the storage elastic modulus of the first adhesive member (1 MPa to 20 MPa). This parameter control ensures that the adhesive member provides appropriate flexibility and rigidity balance, preventing the NULL point phenomenon in the detection signal while maintaining reliable fixation of the plate-shaped member to the housing.
Solution Approach 2:
The patent applies local quality by differentiating the elastic modulus requirements for different adhesive members. The first adhesive member (fixing plate-shaped member to housing) has a storage elastic modulus of 1 MPa to 20 MPa, while the second adhesive member (fixing piezoelectric film to plate-shaped member) has a storage elastic modulus of 0.1 MPa to 10 MPa. This localized optimization ensures proper deformation characteristics at each interface, eliminating the NULL point while maintaining fixation reliability.
2Measurement precision
If the piezoelectric film is bonded to the plate-shaped member, then the pressing force can be detected, but the deformation becomes uneven causing detection inaccuracies
Solution Approach 1:
The patent controls the storage elastic modulus of the second adhesive member (bonding piezoelectric film to plate-shaped member) within 0.1 MPa to 10 MPa. This parameter optimization ensures that the piezoelectric film deforms uniformly with the plate-shaped member during pressing operations, maintaining detection precision while preventing deformation irregularities.
Solution Approach 2:
The patent applies homogeneity by ensuring that the piezoelectric film and the plate-shaped member deform together as a unified structure. The carefully selected elastic modulus range for the second adhesive member (0.1 MPa to 10 MPa) creates homogeneous deformation characteristics, allowing the piezoelectric film to accurately reflect the pressing force without uneven deformation artifacts.
3Reliability
If adhesive members with lower elastic modulus are used, then the plate-shaped member can be fixed, but the deformation of the piezoelectric film becomes uneven
Solution Approach 1:
The patent optimizes the storage elastic modulus of the first adhesive member to 1 MPa to 20 MPa, which provides sufficient fixing capability while maintaining deformation consistency. This parameter range prevents excessive flexibility that would cause uneven piezoelectric film deformation, while still ensuring reliable fixation of the plate-shaped member to the housing.
Solution Approach 2:
The patent applies local quality by assigning different elastic modulus ranges to different adhesive members based on their specific functions. The first adhesive member (fixing plate-shaped member) uses 1 MPa to 20 MPa for structural stability, while the second adhesive member (fixing piezoelectric film) uses 0.1 MPa to 10 MPa for deformation consistency. This localized parameter optimization simultaneously achieves fixing capability and deformation consistency.
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 solution enables precise measurement of the applied force by maintaining consistent deformation patterns, allowing for accurate calculation of the force magnitude applied to the plate-shaped member.
Implementation Method 1
The piezoelectric film is bonded to the plate-shaped member to be bent together with the plate-shaped member. As a result, a pressing force is detected by the output of the piezoelectric film.
Implementation Method 2
the first adhesive member has a storage elastic modulus of 1 MPa to 20 MPa
Data Source
AI summary
An electronic device that includes: a housing; a first plate-shaped member that has a first upper main surface and a first lower main surface that are arranged in a vertical direction, and is fixed to the housing such that a part of a body of a user or an operation member is capable of contacting the first upper main surface; a sensor that detects deformation of the first plate-shaped member; and a first adhesive member in at least a part of a region surrounding the first plate-shaped member as viewed in the vertical direction and which fixes the first lower main surface of the first plate-shaped member to the housing. The first adhesive member has a storage elastic modulus of 1 MPa to 20 MPa.