Press Sensor Adhesive Modulus Tuning to Suppress Rebound
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Solution Overview
Problem
Press sensors using adhesive layers face issues with stress relaxation, leading to false detection due to large rebound forces, which can incorrectly indicate hand release when the user has not actually released pressure.
Innovation Solution
A press sensor configuration with a board, an adhesive layer, and a sensor unit, where the elastic modulus of the adhesive layer is between 7×10^3 Pa and 5×10^5 Pa, and the sensor unit's elastic modulus is lower than the board's, minimizing the influence of rebound and stress relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard adhesive layer is used to fix the press sensor to the support board, then the sensor is firmly attached, but the rebound force increases causing false detection
Solution Approach 1:
The patent applies parameter changes by precisely controlling the elastic modulus of the adhesive layer within the range of 7×10³ Pa to 5×10⁵ Pa. This parameter optimization allows the adhesive to provide sufficient attachment strength while maintaining flexibility to absorb rebound forces, thereby preventing false detection caused by excessive rebound.
2Measurement precision
If the adhesive layer is hard, then the elongation is directly transmitted to the sensor, but the rebound force becomes large causing opposite polarity voltage
Solution Approach 1:
The patent resolves this contradiction by changing the physical parameter of the adhesive layer's elastic modulus to an optimal range. This allows the adhesive to transmit sufficient press force for accurate detection while absorbing excessive rebound energy, preventing the generation of opposite polarity voltage that would cause false detection.
Solution Approach 2:
The adhesive layer acts as an intermediary between the support board and the press sensor. By optimizing its elastic modulus, it mediates the transmission of forces - allowing press forces to be transmitted accurately for detection while absorbing and dampening rebound forces to prevent harmful effects on detection accuracy.
3Object-generated harmful factors
If the adhesive layer is soft, then the rebound is suppressed, but the attachment strength decreases
Solution Approach 1:
The patent resolves this contradiction by precisely determining the optimal elastic modulus range of the adhesive layer. Through parameter optimization, the adhesive achieves a balance point where it provides sufficient attachment strength to secure the sensor while simultaneously suppressing rebound forces to prevent false detection.
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 suppresses the rebound effect, reducing false detection by ensuring the press sensor is less affected by stress relaxation and maintaining accurate detection of hand release.
Implementation Method 1
The viscoelastic body is deformed by a force applied from the outside. At this time, stress relaxation exerts a force on the viscoelastic body to restore the deformation generated in the viscoelastic body to the original state.
Implementation Method 2
The adhesive layer is a so-called viscoelastic body. The viscoelastic body is deformed by a force applied from the outside.
Implementation Method 3
a piezoelectric element that outputs a voltage in response to pressurization
Data Source
AI summary
A press sensor that includes a board, an adhesive material, and a sensor unit on a first main surface of the board with the adhesive material interposed therebetween. When an elastic modulus of the board is E1, an elastic modulus of the adhesive material is EA, and an elastic modulus of the sensor unit is ES, EA<ES and EA<E1.