Piezoelectric element including mesoporous piezoelectric thin film

Abstract

A piezoelectric element includes: an upper electrode having acoustic transparency; a lower electrode; and a diaphragm disposed between the upper electrode and the lower electrode and configured of a mesoporous piezoelectric thin film. The upper electrode, the lower electrode, and the diaphragm are electrically insulated from one another.

What is claimed is: 
     
         1 . A piezoelectric element, comprising:
 an upper electrode having acoustic transparency;   a lower electrode; and   a diaphragm disposed between the upper electrode and the lower electrode and configured of a mesoporous piezoelectric thin film,   wherein the upper electrode, the lower electrode, and the diaphragm are electrically insulated from one another.   
     
     
         2 . The piezoelectric element of  claim 1 , wherein:
 the mesoporous piezoelectric thin film is a mesoporous polyvinylidene fluoride (PVDF) thin film.   
     
     
         3 . The piezoelectric element of  claim 1 , wherein:
 the upper electrode and the diaphragm are connected to each other through an insulator, and   the lower electrode and the diaphragm are connected to each other through the insulator.   
     
     
         4 . The piezoelectric element of  claim 3 , wherein:
 a first air gap is interposed between the upper electrode and the diaphragm, and   a second air gap is interposed between the diaphragm and the lower electrode.   
     
     
         5 . The piezoelectric element of  claim 1 , wherein:
 the lower electrode has acoustic transparency.   
     
     
         6 . The piezoelectric element of  claim 1 , wherein:
 the upper electrode is configured to include a plurality of openings to provide the acoustic transparency.   
     
     
         7 . The piezoelectric element of  claim 1 , wherein:
 the piezoelectric element is configured to operate as one of a speaker or a microphone when power is applied to the piezoelectric element, and   the piezoelectric element is configured to operate as a charging element when power to the piezoelectric element is blocked.   
     
     
         8 . The piezoelectric element of  claim 1 , wherein:
 an AC voltage is applied to the upper electrode and the lower electrode, and   a DC voltage is applied to the diaphragm to generate a sound pressure.   
     
     
         9 . The piezoelectric element of  claim 1 , wherein:
 a DC voltage is applied to at least one of the upper electrode and the lower electrode and the diaphragm, and   an electrical signal corresponding to a sound pressure applied to the diaphragm is generated.   
     
     
         10 . The piezoelectric element of  claim 1 , wherein:
 the upper electrode and the diaphragm are configured to form a first capacitive element,   the lower electrode and the diaphragm are configured to form a second capacitive element, and   the piezoelectric element is configured to detect an acoustic signal by detecting a change in capacitance of at least one of the first capacitive element and the second capacitive element.   
     
     
         11 . The piezoelectric element of  claim 1 , wherein:
 the diaphragm is configured to generate a current corresponding to a received vibration.   
     
     
         12 . The piezoelectric element of  claim 1 , further comprising:
 a capacitive element comprising one terminal electrically connected to the diaphragm.   
     
     
         13 . A wireless charging system, comprising:
 a charging target device including a piezoelectric element which includes a diaphragm configured of a mesoporous piezoelectric thin film; and   a charging device generating a vibration,   wherein the piezoelectric element generates a current by the vibration, and   the charging target device is configured to charge using the current.   
     
     
         14 . The wireless charging system of  claim 13 , wherein:
 the mesoporous piezoelectric thin film is a mesoporous polyvinylidene fluoride (PVDF) thin film.   
     
     
         15 . The wireless charging system of  claim 13 , wherein:
 the piezoelectric element further includes   an upper electrode having acoustic transparency, and   a lower electrode, and   the diaphragm is disposed between the upper electrode and the lower electrode, and   the upper electrode, the lower electrode, and the diaphragm are electrically insulated from one another.   
     
     
         16 . The wireless charging system of  claim 15 , wherein:
 the lower electrode has acoustic transparency.   
     
     
         17 . The wireless charging system of  claim 15 , wherein:
 the upper electrode is configured to include a plurality of openings to provide the acoustic transparency.