To obtain a helical piezoelectric-crystal element which is easy to manufacture and excellent in conversion efficiency, and a method for its manufacture.
A clayey plastic material obtained by mixing piezoelectric ceramic powder with solvent, dispersant, binder, plasticizer and the like is extruded using an extruder into a pipe-shaped member, and conductive films 12a and 12b are formed on the inner and outer faces of the pipe to form a piezoelectric element material 10. Then the piezoelectric element material 10 is helically wrapped around a column 22 on a workbench 21 and is crushed into a specified thickness, by pressing it from above with a plate 23 to form a cylinder. The conductive film is removed from the outer surface of the cylinder by machining or chemical treatment, and electrode lead wires are connected with the conductive films 12a and 12b. Thereafter, firing is conducted at a specified temperature, and a voltage is applied to polarize the conductive films 12a and 12b as a positive electrode and a negative electrode, respectively, thus, a helical piezoelectric-crystal element is completed.
OKAMOTO YASUHIRO
KATSURAGI KOJI
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