Resonator element, resonator, electronic device, electronic apparatus, and mobile object

Abstract

A resonator element includes a substrate having first and second regions. A first region has a vibration region that vibrates with a thickness shear vibration. The first region has first and second surfaces opposite to each other. The second region is integrated with a peripheral area of the first region. The second region has a thickness larger than a thickness of the first region. A first excitation electrode is disposed on the first surface and has a shape obtained by cutting out four corners of an imaginary quadrangle. A second excitation electrode is disposed on the second surface. A ratio (S2 / S1) between an area S1 of the imaginary quadrangle and an area S2 of the first excitation electrode fulfills 87.7%≦̸(S2 / S1)<95.0%.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation patent application of U.S. application Ser. No. 13 / 849,896 filed Mar. 25, 2013 which claims priority to Japanese Patent Application No. 2012-070897, filed Mar. 27, 2012 and Japanese Patent Application No. 2013-027618, filed Feb. 15, 2013 all of which are expressly incorporated by reference herein in their entireties.BACKGROUND[0002]1. Technical Field[0003]This invention relates to a resonator element for exciting a thickness-shear vibration, a resonator, an electronic device, an electronic apparatus, and a mobile object.[0004]2. Related Art[0005]An AT-cut quartz crystal resonator for exciting a thickness-shear vibration as a vibration mode of the principal vibration is suitable for miniaturization and higher frequency, and has a frequency-temperature characteristic showing an excellent cubic curve, and is therefore used in a variety of fields such as an oscillator and electronic equipment. In particular, in recent y...

AI Technical Summary

Benefits of technology

This design achieves a resonator with improved frequency tuning accuracy, increased pulling sensitivity, and reduced ohmic loss, enabling high-frequency operation with enhanced production yield and stability.

Problems solved by technology

However, if the thickness of the vibrating portion is decreased for achieving the higher frequency, there arises a problem that the adjustment sensitivity of the frequency increases to degrade the frequency tuning accuracy, and thus the production yield of the resonator is degraded.

However, if the capacitance ratio γ can be decreased by cutting out the four corners of the excitation electrode to achieve the area ratio of 95% through 98% as disclosed in Document 1 mentioned above, although it is sufficient for the electrical characteristics of the temperature compensated oscillator, in the resonator used for the voltage controlled oscillator, there is a problem that it is unachievable to obtain the pulling sensitivity sufficient to compensate the frequency adjustment accuracy thus deteriorated.

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