High frequency piezoelectric resonator

• US 20020030424A1
• Filed: 12/21/2000
• Published: 03/14/2002
• Est. Priority Date: 12/22/1999
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Miyazaki Epson Corp.
• Inventors: Iwata, Hirokazu
• Granted Patent: US 6,750,593 B2
• Time in Patent Office: Days
• US Class Current: 310/363
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/174 Membranes
• CPC Class Codes: H03H 9/177 of the energy-trap type
• CPC Class Codes: H03H 9/564 implemented with thin-film techniques

Abstract

Disclosed is a piezoelectric resonator that has a piezoelectric plate that has formed thereon a pair of main electrodes and has formed thereon a second electrode surrounding the peripheral edge of the main electrode with a gap being provided between the second electrode and a peripheral edge of the main electrode. The material of the main electrode and the material of the second electrode are differentiated from each other. As the material of the second electrode there is used a material the density of that is lower than the material of the main electrode. With this construction, there is obtained means for suppressing the occurrence of spurious due to an inharmonic mode generating in the high frequency piezoelectric resonator.

Claims

1. A high frequency piezoelectric resonator, the piezoelectric resonator including a piezoelectric plate having disposed on its main surfaces, respectively, mutually opposing main electrodes for the excitation, a pair of second electrodes being each disposed surrounding the peripheral edge of its corresponding main electrode with a gap in between, wherein:

the material of the main electrode and the material of the second electrode are different from each other.

2. A high frequency piezoelectric resonator according to claim 1, wherein the density of the material of the second electrode is made lower than that of the main electrode;

and relevant values of the main electrode, second electrode, and gap are set so that an anti-symmetric 0th mode does not become an trapped mode.

3. A high frequency piezoelectric resonator according to claim 1 or 2, wherein the piezoelectric plate is made a piezoelectric plate having formed therein a recess.

4. A high frequency piezoelectric resonator according to claims 1 to 3, wherein the configuration of the main electrode is made elliptic.

7. A high frequency piezoelectric resonator according to claims 1 to 6, wherein the second electrode is divided into a plurality of portions;

and adjustment of frequency is performed of these electrode portions.

5. A high frequency piezoelectric resonator including a piezoelectric plate, one main surface of the piezoelectric plate being recessed to thereby form a thin portion therein, the main surface opposing the recess corresponding to the thin portion having formed thereon at its central portion a convex portion, the convex portion having formed thereon a main electrode for the excitation, a lead electrode being extended from the main electrode toward an edge of the plate, a second electrode being so provided as to surround the main electrode and the lead electrode with a gap in between, the piezoelectric plate having applied on a recess side thereof an entire electrode.

6. A high frequency piezoelectric resonator according to claim 5, wherein the convex portion is made elliptic.