| 摘要 |
853,473. Hearing aid sets. ZENITH RADIO CORPORATION. Nov. 28, 1956 [Dec. 13, 1955], No. 36370/56. Class 40 (4). A hearing aid set is mounted in a curved container 10 which hangs on the ear and is partly concealed behind it. The set fits either ear. The circuit Fig. 8 comprises a microphone 22 and a receiver 14 coupled by PNP transistors 54 arranged in four stages. A volume control potentiometer 44 is mechanically combined with an on/offswitch 46 controlling a battery 20. The receiver 14 is connected to the main body of the set by a miniature plug 24 parts of the leads being covered by a curved sheath 12 which hooks on to the ear and supports the set. The components are mounted on a chassis 26 of insulating material which is held between the top and bottom portions of the easing as in Fig. 4. The microphone 22 is fitted in an aperture in the chassis by means of a rubber or neoprene gasket 28 and has access to the atmosphere through hole 34 in the microphone cover and hole 36 in the top portion of the casing 10. The microphone and the receiver are so disposed as to avoid acoustic reaction, the instruments being separated by the primo of the ear and the axes being substantially at right angles. The battery 20 is held against a metal plate 42, Fig. 5, by spring contacts 40 at the end of the casing. The on/off switch is operated by a rod 50 which is engaged by a protuberance on the control wheel 16 of the potentiometer 44 at one extremity of its traverse. In one modification, there is no chassis, the components being mounted in one part of the casing, the other part forming a lid. The hooked sleeve 12 may be replaced by an extension of the casing and the leads may be connected to the casing at another convenient part. |
