| 摘要 |
1277912 Piezo-electric microphones STANDARD TELEPHONES & CABLES Ltd 21 April 1970 [30 April 1969] 21953/69 Heading H4J A bone conduction piezo-electric microphone or receiver comprises a thin disc 1 of piezoelectric material, e.g. a mixture of lead and zirconium titanate, with gold nichrome or silver electrodes 2, 3. The disc is bonded to a metal disc 6 having an acoustic stiffness equal to that of the disc 1 or to a second piezo-electric disc. The discs are polarized by the application of a high voltage and are then bonded together with opposite polarity, Fig. 2 (not shown), or the same polarity, Fig. 3 (not shown). The transducer element may be encapsulated in a rubber sheath and is adapted to be retained by a harness in close proximity to the forehead or cheek. The effect of external noise may be reduced by thickening the coating on the rear of the unit, Fig. 4 (not shown). The transducer may also be used in an ear insert microphone, Figs. 6-8 (not shown) with the element either spring loaded against the side of the ear canal or enclosed in a resilient plastics housing having a driving pip. |
