Trapped-energy AT-cut quartz crystal units with grooves

This paper describes a trapped-energy AT-cut quartz crystal resonator with a “groove” on the edge of its electrode which allows: 1. Free shifting of inharmonic spurious responses to another zone of frequency; 2. Smaller displacement at the plate edge; 3. Improved inharmonic spurious responses. This is because it is able to trap the vibration energy more effectively than a resonator without a groove. A theoretical analysis of this resonator was made regarding it as a purely elastic and isotropic body, and was verified by numerical computation using the three-dimensional finite element method