Force Sensor Module AC-Driven Piezoelectric Element
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Solution Overview
Problem
Force sensors using piezoelectric elements face challenges in continuous force measurement due to voltage stabilization when a constant force is applied, as the voltage becomes zero with no further change in force perception.
Innovation Solution
A force sensor module with a piezoelectric element driven by alternating current (AC) power, featuring an attachment layer for partial attachment to a circuit board, allowing impedance changes to be measured between resonance and antiresonance frequencies for continuous force sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is used to measure force by reading voltage, then force measurement is possible, but continuous force measurement becomes difficult when a constant force is applied because the voltage becomes close to zero
Solution Approach 1:
The patent applies dynamics by driving the piezoelectric element with AC power at resonance frequency, causing it to vibrate dynamically. This transforms the static measurement problem into a dynamic one where the piezoelectric element continuously generates voltage through vibration, enabling reliable continuous force measurement even when a constant force is applied.
Solution Approach 2:
The patent utilizes mechanical vibration by exciting the piezoelectric element at its resonance frequency using AC power. The vibration causes continuous mechanical stress on the piezoelectric material, generating a continuous voltage signal that reflects the applied force, thereby solving the problem of voltage stabilization at zero under constant force conditions.
2Stability of the object's composition
If the force sensor is fully attached to the circuit board, then structural stability is improved, but force sensing sensitivity decreases
Solution Approach 1:
The patent applies segmentation by dividing the attachment area of the force sensor into multiple discrete attachment regions rather than full-area attachment. This segmentation allows the sensor to maintain structural stability through distributed attachment points while preserving force sensing sensitivity by leaving portions of the sensor unattached to maintain mechanical freedom for detecting force-induced vibrations.
Solution Approach 2:
The patent applies local quality by creating non-uniform attachment characteristics across the force sensor surface. Specific regions are attached to the circuit board for stability while other regions remain unattached to preserve sensitivity, allowing different parts of the sensor to have different functional properties (attached for stability, unattached for sensing).
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
Enhances force sensing sensitivity by measuring impedance changes within specific frequency ranges, enabling accurate detection of force even under constant conditions.
Implementation Method 1
a piezoelectric element is mainly used as the force sensor. One of the methods of measuring a force using a piezoelectric element is to measure the amount of the force by reading the voltage of the piezoelectric element generated by the force
Implementation Method 2
The AC power may have a resonance frequency, an antiresonance frequency, or a frequency between an adjacent resonance frequency and an adjacent antiresonance frequency
Data Source
AI summary
Provided are a force sensor module and a display device including the same. The display device includes a display panel, and a force sensor module overlapping the display panel, and including a circuit board, and the force sensor partially attached to the circuit board, and including an attachment portion having a surface facing the circuit board and attached to the circuit board, and a non-attachment portion having a surface spaced apart from the circuit board.