Patent GB-1102158-A (GB)
Title: Acoustical coupler
IPC: H04N1/00
Filed: 1966-07-18
Abstract: 1,102,158. Handset mountings. MAGNAVOX CO. 18 July, 1966 [21 July, 1965], No. 32196/66. Heading H4J. An acoustic coupler, for coupling signals into and out of a telephone handset 38 (Fig. 2), to enable facsimile and other signals to be transmitted by way of telephone systems, comprises an electro-acoustic transducer 150 for converting electrical signals to acoustic signals and feeding the latter to the handset microphone 152 and an electroacoustic transducer 150 for converting acoustic signals from the handset receiver 154 to electric signals, the coupler being adjustable for holding a variety of differently shaped and/or proportioned handsets with their microphones 152 and receiver 154 acoustically coupled to the two transducers 150. In the arrangement of Fig. 2, differences in diameter of the faces of the transducers 152 and 154 are met by making a first mounting plate 156 of one transducer 150 slidable in a base plate 158, a lock screw 160 being provided. The angle α between the planes of the microphone 152 and receiver 154 is compensated by varying the tilt of a hinged mounting plate 162 by turning an elevating screw 166. The varying diameters of the faces of the microphone 152 and receiver 154 are accommodated by surrounding the face of each transducer 150 with a compliant convex washer (170), Fig. 3 (not shown), backed by a plane washer (172), Fig. 4 (not shown), to provide an hermetic seal. Fine variation in the angle α between the microphone 152 and receiver 154 is obtained by carrying each transducer 150 by a sponge cylinder (174) or bellows. A cradle 180 is of adjustable length. In a modification (Fig. 5, not shown), the cradle 180 is dispensed with and adjustable felt-covered horseshoes (182, 184) hold the handset in proper orientation. In another embodiment, Fig. 6, the coupler has a metal base 190 resting on a foam rubber sound-insulation pad 192. The transducers 150 are on the seats of two chairs 194 and 196, mounted by gimbals 198 in slides 200 having look screws 202. A sensing switch 204 is activated when the handset 38 is placed in chair 196, providing a signal for indicator lights, ready signals or to activate a transmitting and receiving system. Adjusting screws 206 provide accurate positioning of the handset. In a modification, Fig. 7 (not shown), chairs (194, 196) are clamped inside a box (210) which may be sealed. The chairs (194, 196) are clamped to the box and have their axes of rotation at 120 or 135 degrees. The faces of their transducers are tilted forward and toward each other. In another modification (Fig. 8, not shown), slidable, gimballed transducer mounting units (194, 196) similar to those of Fig. 6 are provided, but a cover (230) having a slot (232) is provided in place of a box. In another variation, handset positioners 236, 238 (Fig. 9) are held by a screw 240 to a housing structure 250. The handset 38 is supported on a rubber vertical member 252 urged upwardly by a spring 260. A microswitch 264 is operated via a cam roller 266 when the handset 38 depresses the support member 252. Vibration damping legs 192 are provided. The space 280 houses electric components (not shown). The transducers 150 are mounted in resilient material 282 loosely held in cans 284.