| 摘要 |
<p>PURPOSE:To prevent the emission of a secondary impulse sonic wave by interposing an O-ring between the outside surface of a support stand and the inside surface of a diaphragm and relaxing the shock due to a load member falling in a rebounding form. CONSTITUTION:An O-ring is interposed between the outside surface of a spiral coil 12 and the inside surface of a diaphragm 11. When a capacitor C is charged and a switch SW is closed to supply a spiral coil driving current of an impulse current waveform to the spiral coil 12, an induced current is generated in the diaphragm 11 and the diaphragm 11 is displaced toward the front surface thereof to strike the surface 15 of the ground and, therefore, an impulse sonic wave is generated in the ground. In this case, since the O-ring 16 is interposed between the outside surface of a support stand 13 and the inside surface of the diaphragm 11, the shock due to the falling of a load member 14 is relaxed and no secondary impulse sonic wave is generated.</p> |
