Patent GB-190703067-A (GB)
Title: Improvements in Printing Telegraphs.
Inventor: WHITE JAMES DUNDAS
Filed: 1907-02-07
Granted: 1907-10-24
Abstract: 3067. White, J. D. Feb. 7. Telegraphs.-The rotation of the type-wheel of a printing-telegraph is effected through a system of selective relays which act to close the circuits of any one, or of any. combination of a number of type-wheel-actuating electro-magnets, by a series of positive and negative, or as when the transmission is wireless, of long and short current impulses. The actuation of the printing - hammer, and the subsequent retraction by a spring of the typewheel to its zero position take place on the cessation of the impulses, by the swinging back of the armature of a sluggish relay in the main circuit, which thereby closes momentarily the local circuit of the printing-magnet. The falling back of the printing- hammer effects, through a pawl mechanism, the feeding forward of the paper strip. As may be seen from the Figure, each actuating-magnet will when energized, due to the arrangement of the pulley mechanism by which the type-wheel is moved, cause a rotation of the type-wheel, different from that caused by the energization of any of the other magnets, and by suitably selecting the magnets to be energized, the typewheel may be rotated to the desired extent. Each actuating-magnet is in a separate local circuit which, when transmission is by positive and negative impulses, is controlled by a polarized relay in one of a series of branches of the main circuit. When transmission is by impulses of different durations, the place of the polarized magnet is taken by two relays, one quick-acting and the other rendered sluggish by a dash-pot arrangement. The two cases are similar and the former only will be described. When an impulse flows from line through the first branch circuit 66, the armature 77 of the polarized relay closes a local circuit either at contact 82, or contact 81, according to the sign of the impulse. If the impulse be positive, the actuating-magnet 53 is included in the local circuit, while if the impulse be negative, the local circuit does not include the magnet 53, and a negative impulse does not, therefore, cause a rotation of the type-wheel. The local circuit, once closed, is held closed until broken at another point, by the attraction on the relay armature 77, of the magnet 79 or the magnet 80, in the local circuit. When the impulse ceases, the circuit 66 is broken at contact 73 by the attraction to the contact 100 of the soft-iron armature 72 by a magnet 87 in the local circuit. The circuit 66 being broken, and a resistance 99 being short - circuited through the tongue 72 and the contact 100, a path is clear for a second impulse to flow, this time in the branch circuit 67, and as before, according to the sign of the impulse, the actuating - magnet 51 may or may not be energized, but a way will be cleared for the third impulse to flow in the branch circuit 68. In this manner, any one, or any combination of the actuating-magnets may be energized. The printing-stroke which occurs after the cessation of the impulses, is effected through the relay 107 in the main circuit. Normally, the tongue 108 of the relay hangs just clear of a second tongue 110. When the current impulses are flowing, the tongue 108 is attracted by its magnet 107, but when the impulses cease, the tongue 108 swings back and makes momentary contact with the tongue 110, thus closing the circuit through the printing-magnet 12. The actuation of the printing-lever 9 by the magnet 12 allows the arm 130 momentarily to close, at contact 129, a local circuit containing the magnets 121, 122, &c. These magnets when energized attract their armatures 84, 113, &c., thus breaking the local circuits which were closed by the series of impulses. The armatures of the relays in the various branch circuits 66, 67, &c. may then reassume their original positions ; the actuating- magnets are de-energized ; and the type - wheel assumes its zero position under the influence of the spring 25. The falling back of the printing- lever 9 after the printing-stroke effects, through the system of levers 15, 17, 19, and the pawl 22, the feeding of the paper strip 6. Specification No. 17,562, A.D. 1904, is referred to.