| 摘要 |
A crystal oscillator comprises a rectangular circuit substrate for mounting circuit devices and its metal cover, said circuit substrate has grooves on each long side and on each short side and said metal cover has projections at each aperture end corresponding to the grooves, and which has a swelling from external to internal in each of the projections, wherein both the grooves provided on each short side and the projection of said metal cover are provided at one end of each long side or each short side.
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