| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure stiffness of a vibration arm and to improve a stability of a vibration. <P>SOLUTION: A groove 36 extending in a direction of a straight side of a vibration arm 18 is formed in a first surface 12 and a second surface 14. The groove 36 includes a first inner surface 33 extending back on to a first side 32, a second inner surface 35 extending back on to a second side 34, a bottom surface 37 between the first inner surface 33 and the second inner surface 35, and a third inner surface 39 and a fourth inner surface 41 connected to both ends in the direction of the straight side of the bottom surface 37 and both ends in the direction of the straight side of the first and second inner surfaces 33 and 35. The first surface 33 and the second surface 35 of the groove 36 formed on the first surface 12 are nonparallel to each other, parallel to a straight side of a vibration arm 18, and is plane-symmetric with respect to a symmetric surface S<SB>1</SB>vertical to the first surface 12 and the second surface 14. The first inner surface 33 and the second inner surface 35 of the groove 36 formed on the second surface 14 are nonparallel to each other, and is plane-symmetric with respect to the symmetrical surface S<SB>1</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT |
