| 摘要 |
An IT-cut quartz crystal unit has a discoidal or a rectangular quartz crystal blank which is cut from a crystal of quartz along a plane perpendicular to the Y-axis of the crystal of the quartz which is rotated over approximately 34° about the X-axis, and further rotated from this rotated position over approximately 19° about the Z-axis. Excitation electrodes are formed on both main surface of the crystal blank, respectively. The crystal blank is held at positions in at least one set of opposing peripheral regions selected from an angular range of 18°±18° from the Z'-axis on the surface of the crystal blank, viewed from the center on the surface of the crystal blank; an angular range of 198°±18° from the Z'-axis; an angular range of 108°±18° from the Z'-axis; and an angular range of 288°±18° from the Z'-axis.
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