GB501696A - Telephone handset with combined transmitter and dial - Google Patents

Abstract

501,696. Sets; transmitters. STANDARD TELEPHONES & CABLES, Ltd. March 18, 1938, No. 8415. Convention date, April 28, 1937. [Class 40 (iv)] In a telephone hand- Set comprising a handle with a receiver mounted in a receiver housing at one end and a transmitter housing at the other end, a combined dialling and transmitter unit is mounted in the transmitter housing. The handle 1 has a receiver portion 3 and a transmitter housing 2 in which a frame 6 carrying the transmitter and dial unit is mounted by means of a ledge 7 and a threaded ring 8. The microphone transmitter, which comprises flexible metal bellows 22 enclosing granulated carbon, is mounted in a recess 17 of a thimble 15 secured to a rotatable sleeve 13 mounted in a bearing portion 11 secured to the frame .6 by spokes 12. The member 15 is secured to a collar 20 which is provided with perforations and engages with the diaphragm 26 in such a way as to place it under tension. The collar 20 is also connected to a finger plate 21 carrying a perforated card 59. The sleeve 13 carries a gear-wheel 28 meshing with a gear-wheel 30 driving an impulse cam 29 which operates contacts carried by springs 42 and off-normal contacts carried by springs 46, 46, 47. Contact members 49 . . . 52 engage with springs 53 ... 56 moulded in the transmitter housing and springs 57, 58 engage with a pin 23 connected to the transmitter capsule and with the end of the shaft 13 which is connected to the metal bellows 22. In a modification, Fig. 5 (not shown), the microphone is mounted on a yoke attached to the frame 6 and is independent of the rotation of the sleeve connected to the finger plate of the dialling mechanism. The ,diaphragm is clamped at its periphery by a flanged ring. The hand-set may be supported on a casing secured at the side of an office desk or table, Fig. 6 (not shown).