| 摘要 |
PURPOSE:To control directivity by joining a small diameter cylinder shorter than a large diameter part to the opening of a large diameter cylinder by a joining member, attaching a piezo-electric vibrating member to free end of the small diameter part, blocking up another end of the small diameter part, blocking up another end of the large diameter part and adjusting the length of the small diameter part. CONSTITUTION:A large diameter cylindrical case 17 and a shorter small diame ter cylindrical case 11 are joined by plural radial joining members 12. A vibrating member consisting of a piezo-electric magnetic vibrator 1 and a metal lic diaphragm is bonded to the free end of the small diameter case 11 with elastic bond 13. A sealing board 14 is fitted to the open and of the large diame ter case 17. Lead wires 15a, 15b are connected to the piezo-electric magnetic vibrator 1 and diaphragm 2 through insertion holes 16a, 16b of the sealing board 14. A conical resonator 4 is attached to the center of the diaphragm 2. Two resonators are formed inside and outside of the cylindrical case 11. Thus, high sensitivity characteristic is obtained, and at the same time, directivity is controlled easily by adjusting the length of the case 11. |
