GB418388A - Manually operable selectors suitable for use in intercommunicating telephone systems - Google Patents

Abstract

418,388. Intercommunication systems. SHIPTON, E., 12, Dartmouth Street, West. minster. May 5, 1933, No. 13130. [Class 40 (iv).] A manually-operable selecting switch for use in an intercommunicating telephone system comprises an operating member, such as the finger hold type used in automatic telephone dials, which can be manually operated to move a contact wiper to a position corresponding to a station to be called, said operating member being restored to normal when released, while the wiper is retained in the position to which it is moved and is restored to normal after use on operation of a releasing member which may be operated by the replacement of the telephone instrument. As shown in Fig. 3, the finger hold plate 3 when rotated causes a roller 14 to engage an upturned projection 13<d> of an operating member 13, the rotation of which causes a wiper 15 to move to the desired contact of a series 8. A ratchet wheel 17 is arranged to move with the operating member 13 and wiper 15 and when the finger hold plate is released a pawl 21 is pressed against the ratchet plate by the blade spring 23 so that the contact arm 15 is retained in the desired position. The finger hold plate is, however, returned immediately to its normal position by a spiral spring retained in the casing 6, the roller 14 being disengaged from the projection 13<a> and when fully returned, the roller engages and closes spring blade contacts 31, 32. As shown in Fig. 4, these contacts connect the battery supply to the speech circuit and the arrangement thus prevents any clicks from being heard at any station which is already speaking when the wiper of another calling station passes over the corresponding contact. The switch member 15 and operating member 13 are returned automatically to the initial position shown on replacement of the telephone instrument, the weight of which depresses a button 29 at the end of a sliding rod which is connected at its lower end by a pin-and-slot connection to a pivoted arm 28 having a shaped nose for engaging the downturned end 24 of the detent 21. The latter is disengaged from the ratchet wheel 17 and the members 13, 15 are returned by a spiral spring within the casing 16, the shock at the end of their travel being absorbed by one end of a spring 50 which projects through and has limited movement within an aperture 52. A telephone cradle switch mechanism 36 is operated by the replacement of the instrument, contacts 40 being closed and contacts 41, 42 being opened. A retarder 38 and buzzer 37 are mounted on the detachable base 39 of the instrument casing 1 which also carries a calling push button 33 with contacts 34, 35.