Abstract: A piezoelectric vibration device utilizes a thickness-shear vibration available for communication devices or the like. The piezoelectric vibration device has a structure wherein at least one of each peripheral zone of an input electrode (21) and an output electrode (22), or a common electrode (23), where the non-harmonic overtone mode is relatively strongly excited, is partially provided with either a weight reducing portion (231, 232) or a weight adding portion. Moreover, an area of the common electrode (23) is larger than a total area of the input electrode (21) and the output electrode (22), and either the weight reducing portion (231, 232) or the weight adding portion reaches the common electrode (23) opposed to the input electrode (21) and the output electrode (22). Preferably, the common electrode formed on one principal plane of a quartz plate (1) is twice to 10 times as thick as the input electrode (21) and the output electrode (22) formed on the other principal plane.

Abstract: A piezoelectric filter element 1 is supported by the periphery of a package body 21 of the surface mounting type such that a pair of input/output oscillating electrodes 11, 12 of the piezoelectric filter element 1 face the package body 21. The package body 21 has a shield electrode 30 which extends along a gap G between the pair of input/output oscillating electrodes 11, 12, which presents a grounding potential, and which is apart away by a predetermined distance from a piezoelectric substrate 10. The shield electrode 30 is formed as extending along the gap G and does not face, in a broad area, the pair of input/output oscillating electrodes 11, 12. This prevents floating capacitance from being generated between the shield electrode 30 and the pair of input/output oscillating electrodes 11, 12.

Abstract: In a multiple-stage-connected multiple-mode piezoelectric filter unit having a single container 1 in which there are connected, in cascade, two multiple-mode piezoelectric filter elements comprising at least one piezoelectric substrate and two electrode groups each comprising a pair of input/output electrodes and a grounding electrode, the electrode pairs being formed on one side of the piezoelectric substrate with a predetermined gap provided and the grounding electrodes being formed on the other side of the piezoelectric substrate at positions respectively opposite to the electrode pairs, it is an object of the present invention to enhance the ability of preventing the two filter elements from being coupled with each other, thus facilitating the final adjustment thereof. Formed in a single container 1 are two piezoelectric substrates 2, 3 on each of which formed are a pair of input/output electrodes and a grounding electrode.