Piezoelectric transformer having improved electrode arrangement

Claim 1

A piezoelectric transformer comprising: a long relatively thin rectangular body of piezoelectric material, said body having first and second major surfaces and exhibiting a resonance mode of vibration at a predetermined frequency in a longitudinal direction thereof, said body being divided into a plurality of regions in said longitudinal direction, first and second electrodes applied respectively to said first and second major surfaces of a first region of said plurality of regions, said first region being polarized in a thickness direction of said body; and third and fourth electrodes which are formed such as to respectively cover opposite side surfaces of a second region of said plurality of regions in a plane parallel to said longitudinal direction of said body and to respectively extend inwardly in a transverse direction of said body by a predetermined amount over said first and second major surfaces of said second region, said second region being polarized in a direction perpendicular to said longitudinal direction, wherein said plurality of regions further include: a third region which is provided outside of said second region, said third region being provided with fifth and sixth electrodes applied respectively to said first and second major surfaces of said third region, said third region being polarized in a thickness direction of said body, and a fourth region which is provided between said second and third regions, said fourth region being provided with seventh and eighth electrodes which are formed such as to respectively cover opposite side surfaces of said fourth region in a plane parallel to said longitudinal direction of said body and to respectively extend inwardly in a transverse direction of said body by a predetermined amount over said first and second major surfaces of said fourth region, said fourth region being polarized in a direction perpendicular to said longitudinal direction.