| 摘要 |
919,282. Horns and resonators. ZENITH RADIO CORPORATION. May 13, 1959 [May 15, 1958], No. 16401/59. Class 13. [Also in Groups XXXIX and XL (b)] To obtain better coupling with air a transducer, worked at mechanical resonance to transmit or receive a signal frequency, has a structure attached to it with the same frequency of mechanical resonance and such as to provide a greater amplitude of vibration. The invention is applied to a magneto-strictive transmitter and to a piezo-electric receiver. The resonant structure may be a metal bridge 20 soldered to one side of a crystal bimorph 11, 12, Fig. 6; the legs 21 of the bridge straddling the direction in which the bimorph bends. The structure may alternatively comprise a closed cylinder, Fig. 11a; a bridge with cantilever arms 12a; or a disc mounted on a post, Fig. 13a. Any of these structures may be attached to the end of a centre-mounted magneto-strictive rod; Fig. 14 (not shown). More than one structure may be mounted side-by-side on a piezoelectric crystal, Fig. 10, each structure cooperating with a quarter wavelength aperture 46 communicating with the throat of a horn. The horn is shown in section at 45 in Fig. 1 and is of rectangular cross-section with the width of its orifice half its height to give a wide angle for lateral reception. The horn may be exponential. Specifications 867,764 and 867,765 are referred to.
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