1. Technical Field
The present invention relates to a resonator element having resonating arms, and a resonator.
2. Related Art
In a resonator having a resonating arm, a resonator element is known in which the resonating arm vibrates in a thickness direction thereof in addition to one in which the resonating arm vibrates in a plane as flexural vibrations. The resonator element generally has a plurality of resonating arms so as to perform walk-mode vibration in which the resonating arms adjacent to each other alternatively vibrate in opposite directions from each other.
JP-A-2008-224627 is an example of related art. The example discloses an angular velocity sensor using the walk-mode vibration. The angular velocity sensor has three arms (resonating arms) formed of silicon, for example. On one surface of each arm, a lower-layer electrode (lower electrode), a piezoelectric thin film (piezoelectric film), and an upper-layer electrode (upper electrode) are formed in this order. The lower-layer electrode, the piezoelectric thin film, and the upper-layer electrode form a piezoelectric element. Thus, each of the resonating arms can vibrate in a thickness direction of a resonator element by the reverse piezoelectric effect of the piezoelectric thin film. A polarity of each electrode is set such that the arms adjacent to each other vibrate in opposite directions from each other.
In the resonator element, wiring lines respectively coupled to the lower-layer electrode and the upper-layer electrode are arranged on one surface of the resonator element so as not to intersect with each other. Therefore, the arrangement of wiring lines becomes complex and a large area is required for the arrangement.
In the configuration disclosed in the example, the area of the resonator element decreases and it becomes hard to ensure wiring paths especially when the resonator needs to be downsized. As a result, it is hard to realize the miniaturization of the resonator element.