Piezoelectric Force Sensor Plate Stiffness Optimization
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Solution Overview
Problem
Existing electronic devices with pressing sensors struggle to accurately detect the magnitude of the force applied by a user to the operation panel.
Innovation Solution
The electronic device includes an operation panel, a buffer member, a plate-shaped member, and a sensor. The plate-shaped member is fixed to the buffer member, and the sensor is attached to the plate-shaped member to detect deformation of the operation panel. The product of the Young's modulus of the plate-shaped member and the cube of its thickness is optimized to 1.6×10−3 N·m to 1.6 N·m.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressing sensor uses a piezoelectric film bonded to a plate-shaped member to detect pressing force, then the sensor can detect the presence and direction of pressing operations, but the magnitude of the pressing force cannot be accurately detected
Solution Approach 1:
The patent optimizes the physical parameters of the plate-shaped member, specifically setting the product of Young's modulus and the cube of thickness (E·t³) within a specific range (1.6×10⁻³ N·m to 1.6 N·m). This parameter optimization enables the plate to deform appropriately under pressing force, allowing the piezoelectric film to generate sufficient output signal for accurate force magnitude detection while preventing excessive deformation that would cause overshoot.
Solution Approach 2:
The patent introduces a buffer member between the operation panel and the plate-shaped member to dynamically control the deformation characteristics. The buffer member absorbs excess energy and regulates the deformation process, preventing overshoot while maintaining sensitivity to pressing force magnitude. This dynamic element allows the system to adapt to varying pressing forces accurately.
2Measurement precision
If the plate-shaped member is made thinner to improve sensitivity, then the detection sensitivity increases, but overshoot occurs in the deformation response
Solution Approach 1:
The patent establishes a specific range for the product of Young's modulus and the cube of thickness (E·t³) to balance sensitivity and stability. This parameter optimization allows the plate to be sufficiently thin for high sensitivity while maintaining structural integrity to prevent overshoot. The mathematical relationship E·t³ = 1.6×10⁻³ N·m to 1.6 N·m provides a quantitative basis for achieving both sensitivity and deformation stability.
Solution Approach 2:
The buffer member is positioned beforehand between the operation panel and the plate-shaped member to prevent overshoot before it occurs. This cushioning element absorbs excess energy and regulates the deformation process, allowing the use of thinner plates for high sensitivity without experiencing unstable deformation or overshoot in the detection response.
3Stability of the object's composition
If the plate-shaped member is made thicker to reduce overshoot, then deformation stability improves, but detection sensitivity decreases
Solution Approach 1:
The patent optimizes the thickness parameter within a specific range defined by the relationship E·t³ = 1.6×10⁻³ N·m to 1.6 N·m. This optimized thickness provides sufficient structural stability to prevent overshoot while maintaining adequate sensitivity for force magnitude detection. The mathematical relationship quantitatively defines the optimal thickness that balances both requirements.
Solution Approach 2:
The buffer member is introduced to dynamically adjust the system's deformation characteristics, allowing the use of thicker plates for stability while recovering sensitivity. The buffer member's elastic properties compensate for the reduced sensitivity of thicker plates, maintaining overall detection performance while achieving stable deformation without overshoot.
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 allows for accurate detection of the force magnitude applied by the user, minimizing overshoot and enhancing the accuracy of force measurement.
Implementation Method 1
a piezoelectric film that 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
Data Source
AI summary
An electronic device that includes: an operation panel having an upper main surface and a lower main surface; a buffer member that has an upper main surface and a lower main surface, and is fixed to the lower main surface of the operation panel; a plate-shaped member that has an upper main surface and a lower main surface, and is fixed to the lower main surface of the buffer member; and a sensor that is fixed to the lower main surface of the plate-shaped member and detects deformation of the operation panel. A value of a product of a Young's modulus of the plate-shaped member and a cube of a thickness of the plate-shaped member is 1.6×10−3 N·m to 1.6 N·m.