PIEZOELECTRIC CERAMIC RESONATOR

• US 3,745,385 A
• Filed: 01/31/1972
• Issued: 07/10/1973
• Est. Priority Date: 01/31/1972
• Status: Expired due to Term

• Current Assignee: Kiyokazu Hagiwara, Reiichi Sasaki, Takashi Nagata, Yasuo Nakajima
• Original Assignee: Kiyokazu Hagiwara, Reiichi Sasaki, Takashi Nagata, Yasuo Nakajima
• Inventors: Nagata, Takashi, Sasaki, Reiichi, Nakajima, Yasuo, Hagiwara, Kiyokazu
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Budd, Mark O.
• Application Number:
  US05/222,254
• Time in Patent Office: 526 Days
• Field of Search: 310/8.1,8.2,9.5,9.6,8.5,9.1 333/30,72R
• US Class Current: 310/358
• CPC Class Codes: H03H 9/176 consisting of ceramic material H03H9/177, H03H9/178 take precedence

Abstract

A piezoelectric ceramic resonator vibrating resonantly in a thickness-shear vibration mode, which is free from unwanted vibrations in a high frequency range. The piezoelectric ceramic resonator comprises a thin wafer of piezoelectric ceramic material polarized in a direction parallel to the major surfaces thereof. A tetragonal electrode is applied to a part of one of the major surfaces, and a counter electrode is applied to another of the major surfaces, the counter electrode being at least as large as the area of the tetragonal electrode. Two slots are positioned along the opposite edges of the tetragonal electrode. The two slots have walls which are perpendicular to the major surfaces and the slots are at least as long as the opposite sides of the tetragonal electrode. At least one of the two slots has the ends closed by being spaced inwardly from the edges of the wafer.

Claims

1. A piezoelectric ceramic resonator vibrating resonantly in a thickness-shear vibration mode, said resonator comprising:

a thin wafer of piezoelectric ceramic material which is polarized in a direction parallel to the major surfaces thereof;

electrode means consisting of a tetragonal electrode applied to part of the area of one of said major surfaces, a counter electrode applied to the other of said major surfaces opposed to said tetragonal electrode and having an area at least as large as said tetragonal electrode; and

said wafer having two slots therein along the opposite side edges of said tetragonal electrode and which slots have the walls thereof perpendicular to said major surfaces, said slots being at least as long as said opposite side edges, at least one of the two slots having the ends closed by being spaced inwardly from the edges of said wafer.

2. A piezoelectric ceramic resonator as claimed in claim 1, wherein each of said two slots has the side along said tetragonal electrode straight and parallel to said polarization direction.

3. A piezoelectric ceramic resonator as claimed in claim 1 wherein at least one of said two slots has the ends spaced inwardly from the edges of said wafer a distance greater than three times the thickness of said wafer.