Piezoelectric Device Resonance Frequency Control
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Solution Overview
Problem
Piezoelectric sensor devices face challenges in providing effective tactile feedback due to frequency shifting when mounted on printed circuit boards, which reduces human perception, and assembly using pick-and-place technology is complicated by the need for precise electrical connections through adhesive layers.
Innovation Solution
A piezoelectric device configuration with a sheet of piezoelectric material mounted on a circuit board featuring conductive layers with openings and extensions, allowing for down-shifting of resonance frequency for improved tactile feedback and simplified assembly by eliminating the need for additional electrical connections through adhesive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the piezoelectric element is mounted on a printed circuit board, then the device structure is stabilized and electrical connections are established, but the resonance frequency shifts to a higher frequency which reduces tactile feedback perception
Solution Approach 1:
The conductive layer is segmented by creating openings that divide it into separate regions. The piezoelectric element is positioned over these openings, allowing it to be electrically connected to the conductive layer while mechanically isolated from rigid mounting, thus maintaining low resonance frequency for tactile feedback while ensuring structural stability and electrical connectivity
Solution Approach 2:
The openings in the conductive layer act as an intermediary structure that enables electrical connection between the piezoelectric element and the conductive layer without requiring rigid mechanical mounting. This intermediary arrangement allows the element to vibrate freely for tactile feedback while maintaining electrical connectivity and structural stability
2Ease of manufacture
If traditional mounting methods are used with adhesive layers, then electrical connections can be established, but additional puncturing of adhesive layers is required which complicates assembly
Solution Approach 1:
The openings are pre-formed in the conductive layer during board manufacturing, before assembly. This preliminary action eliminates the need for subsequent puncturing operations during assembly, simplifying the manufacturing process while ensuring proper electrical connections are established
Solution Approach 2:
The complex adhesive layer puncturing step is extracted and eliminated from the assembly process. The electrical connection path is reconfigured to go through the pre-formed openings in the conductive layer, removing the need to puncture adhesive layers and simplifying the overall assembly process
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 configuration enhances tactile feedback perception by aligning resonance frequencies with human sensitivity and simplifies assembly by enabling accurate placement and electrical connection without puncturing adhesive layers, improving both feedback and manufacturing efficiency.
Implementation Method 1
Bending of the piezoelectric material generates a voltage that can be detected
Implementation Method 2
an element comprising a sheet of piezoelectric material can be made vibrate by applying a voltage over the sheet of piezoelectric material
Implementation Method 3
Curve a in FIG. 1 illustrates the strength of resonance as a function of frequency for an element comprising a sheet of piezoelectric material
Data Source
AI summary
A piezoelectric device comprises at least one element comprising at least one sheet of piezoelectric material. The element is mounted on a circuit board comprising at least one conductive layer having at least one opening. The element is located on the opening and supported by edges of the opening in such a manner that the opening extends laterally beyond the area of the sheet of piezoelectric material. The element is sandwiched between an overlay and the circuit board in such a manner that vibrations of the sheet of piezoelectric material are sufficient to cause vibration of the overlay.