SPURIOUS VIBRATION SUPPRESSION TYPE ULTRA THIN PLATE MULTIPLE MODE PIEZOELECTRIC FILTER ELEMENT

摘要

PURPOSE:To facilitate mass-production and to suppress spurious vibration in an excellent manner by dividing one or both electrodes via a prescribed gap and forming at least a point or a linear projection integrally onto a vibrating part. CONSTITUTION:A thin vibrating part 2, a ring surrounding part 3 supporting therearound, and a projection 4 on the surface of the vibrating part 2 are integrally formed from one piezoelectric raw plate, an electrode is adhered to two faces of the vibration part 2 opposed to each other, and at least one of them is divided at a prescribed gap. That is, a split electrode is formed nearly in the center of the vibrating part 2 of the flat faces opposed to each other. Thus, the projection 4 is formed by only changing a mask pattern to form an etching protection film without varying the manufacture process. Furthermore, since no positional deviation is caused substantially in an etching technology, prescribed spurious vibration only is suppressed without affecting on the main vibration and the dispersion in the characteristic is limited.