Patent GB-190408657-A (GB)
Title: Improvements in Printing Telegraph Receivers.
Inventor: WHITE JAMES DUNDAS
Filed: 1904-04-15
Granted: 1904-12-15
Abstract: 8657. White, J. D. April 15. Telegraphs.- Relates to improvements in page - printing telegraph receivers of the type described in Specifications No. 24,025, A.D. 1903, and No. 2865, A.D. 1904, :in which lateral movements of the type or paper are rendered unnecessary by the provision of a type-cylinder bearing a large number of type, the successive impressions being effected by forming the printing-hammer as a cylinder bearing impact faces arranged on a helical line. According to the present invention, the type-cylinder bears type of three kinds, viz., capitals, small letters, and figures, circumferential rows of type in that order being repeated over and over again throughout the length of the type-cylinder. In the arrangement shown in Figs. 1 and 2, the step-by-step movements of the type-cylinder 6 are produced by positive currents in the line-wire 1, and the movements of the hammercylinder 7 are produced by negative currents, polarized electromagnets 2, 4 being used for that purpose. The movements of the type-cylinder, which runs in contact with an inking- roller 13, are effected by the action of the bifurcated lever 18 on the toothed wheel 17, such a succession of positive line-currents being sent as will bring the desired type to the impression point 22. The negative current which follows causes the armature 27 to be attracted, the frame 25 being swung about its pivots 26 so as to bring one of the impact faces 23 on the hammer-cylinder 7 against the selected type. As the cylinder 7 returns to the normal position, the pawl 31 acts on the ratchetwheel 29 to rotate the cylinder through one step, so that the next impression takes place from the next impact face in the series. In order that capitals, small letters, and figures shall not be printed alternately, as they would be if the typecylinder received movements of rotation only, it is given a regular succession of axial movements, consisting first of a movement of one space to the right, then of a second movement of the same kind, and finally of a leftward movement of two spaces. Under these conditions the successive impressions all take place from circumferential rows of the same kind, the same row of type being used in succession for three impact faces and then the next row of the same kind. The axial movements of the type-cylinder are effected as follows. At each backward swing of the hammer-cylinder, the pawl 76 turns the ratchet-wheel 73 through one step. A wheel 72 bearing one tooth or cam for every three teeth on the wheel 73 consequently causes the lever 78 to assume successively three different positions. In the position shown in Fig. 1, no current is supplied from the battery 70 to the circuit 64. At the next step, the T-piece 81 depresses the lever 86, which carries an insulating- projection 88, and contact is established at 84, 82 and 78, 86. Current then flows in the circuit 64 in such a direction as to energize the electromagnet 63 but not the electromagnet 66. The typecylinder is consequently drawn one step towards the right, against the tension of the controlling- spring 55. At the next movement of the ratchetwheel 73, the lever 78 drops off the tooth of the wheel 72 and the T-piece 81 moves upwards sufficiently to lift the lever 84, thus making contact at 81, 84 and 86, 82. The current from the battery 70 now flows in the circuit 64 in such a direction that both the electromagnets 63, 66 are energized, the type-cylinder being drawn further towards the right than was previously the case. After the next impression, the lever 78 returns to the position shown in Fig. 1, both the electromagnets 63, 66 being de-energized, and the typecylinder moving back two spaces towards the left. When the line-currents are such as to bring the " space 11 to the impression-point, an arm 12 prevents the full movement of the cylinder 7 by acting as an abutment for the arm 33. In consequence, although the pawl 31 turns the ratchet-wheel 29 through one step as usual, the pawl 76 does not effect an advance of the wheel 73, and no axial movement of the type-cylinder takes place. The next impression therefore takes place from the next kind of type in order. If two consecutive spaces are sent, a change to the third kind of type is effected, but after three consecutive spaces the impression is from type of the same character as those previously used. In ordinary work, therefore, three spaces are sent between words. Line-spacing is effected by means of the paper feed-rolls 46, 36, the electromagnet 43 being energized by the action of the pin 52 on the contacts 50 after each complete revolution of the cylinder 7. The type-wheel may be spring-driven, an escapement being actuated by a succession of line-currents alternating in sign. The movement of the hammer-cylinder is in that case produced by a sluggish electromagnet energized by a prolonged current of either sign. A two-wire system is described in which a positive or negative current sent through a second circuit acts independently to advance the ratchet-wheel 73 or the ratchet-wheel 29 respectively. By this means, a change of " case " without a space, or a single space without a change of "case" can be produced. In a further modification, a gravity "tumbler" is pivoted at the end of the arm 12, with the effect that a single space does not cause a change of case, owing to the fact that the full movement of the arm 33 and frame 25 is not interrupted. If two consecutive spaces are sent, however, the " tumbler," having been thrown over by the first impact, acts as an abutment for the arm 33 on the second occasion, and a change of case takes place. The paper may be fed forward slightly after each impression, the printing then taking place in the form of lines inclined slightly downwards towards the right. If, however, the paper is itself fed at a slight angle to the cylinders, the lines can be printed straight across it. The rocking frame 25 may support the cylinder 7 from beneath instead of from above. The polechanging device 78 &c may be modified by omitting the insulating-projection 8, the battery being then short-circuited when the lever 78 is in the mid-position.