Patent GB-165569-A (GB)
Title: Improvements in or relating to call indicators for telephone systems
IPC: H04M3/64
Filed: 1920-04-14
Abstract: 165,569. Automatic Telephone Manufacturing Co., Ltd., Savin, J., and Smith, S. R. April 14, 1920. Addition to 129,563. Order apparatus.-Relates to a modification of the call indicator for signalling a telephone subscribers' number to a manual operator, described in the parent Specification. A plurality of number wheels rctatably mounted on a shaft 3, Fig. 3, and adapted to be actuated successivelv in a step-by-step manner by impulses transmitted by a subscriber, are now controlled by separate pawls 30 (one for each number wheel) which are rendered operative in succession to rotate their corresponding number wheels. The number wheels are adapted to be rotated by the ratchet-wheels 10, Figs. 2 and 3, and normally rest with their pins 11 pressing against the combined stop and pawl-guiding members 12. Mounted parallel to the shaft 3 is a spindle 13 having ratchet wheels 14, 15, cut at each end and provided with staggered flats 54 - - 57, Fig. 4, one for each number-wheel, each flat coming successively under a stepping pawl 30 to render it operative as the spindle 13 is rotated. At right-angles to the axis of the shaft 3 are arranged three operating magnets, viz. a selector magnet 18, a stepping magnet 19, and a release magnet 20. The armature 21 of the selector magnet 18 has pivoted to it an extension piece 22 ending in a pawl which engages with the ratchet 14 and effects the rotation of the spindle 13. The stepping-magnet 19 is provided with an armature 24, on the pivoted extension pieces 25, 26 of which is mounted a frame 28 carrying a shaft 29 on which are mounted the pawls 30. A pawl 30, however, does not engage with its corresponding ratchet 10 unless it rests upon a flat on the spindle 13. The armature 31, Fig. 1, of the release magnet 20 is pivotally connected to a lever 23 engaging the ratchet 15. The operation of the device is described with reference to a system in which an automatic subscriber is first connected to an idle junction line leading to a manual exchange and a rotary switch is then energized to select an idle number indicator. A holding relay 43, Fig. 6, is thereby energized over a. wiper 42 of the rotary switch. The subsequent response of the release relay 45 causes the energization of magnets 18 and 20, the magnet 18 rotating the spindle 13 one step and the magnet 20 preventde-energization of the selector magn.et 18, but on brought under the pawl 30 of the number wheel 4, and allows this pawl only to engage with the ratchet 10. Projections 48 on the spindle 13 also move from engagement with release levers 49, Fig. 2, which engage with the ratchets 10 to prevent their clockwise rotation. Impulses dialled by the subscriber now operate the stepping magnet 19 to set the first number wheel 4. The response of the series relay 47 causes the deenergization of the selector magnet 18, but on the cessation of the first series of impulses it steps the spindle round to the next position, in which the flat 54, Fig. 4, is brought under the pawl 30, of the second number wheel 5, which on the transmission of the next series of impulses is rotated to show the next digit. The operation previously described is then repeated for further digits. After the last digit has been dialled the selector 18 is again energized to rotate the spindle 13 a further step, which causes the projections 48 to separate the springs 53 and break the circuit of the stepping-magnet 19. A lamp may also be lighted to indicate that the call is completed. Insertion of the junction line plug into the jack of the required number causes the de-energization in turn of the relays 43, 45 and the magnets 20, 18. The release magnet 20 permits the spindle 13 to return to its normal position in which the projections 48 engage with the levers 49 to release the number wheels. Specification 166,351, [Class 40 (iv), Telephones &c.], is referred to. Specification 163,807 is referred to in the Provisional Specification.