Patent GB-190716778-A (GB)
Title: Improvements in Printing Telegraph Receivers.
Inventor: WRIGHT JOHN EDWARD
Filed: 1907-07-22
Granted: 1908-05-14
Abstract: 16,778. Wright, J. E. July 22. Telegraphs.-In a pageprinting telegraph receiver having a type-wheel of cylindrical form with several rows of type, separate escapement mechanisms are provided for respectively raising and rotating the typewheel step-by-step. The escapement mechanism effecting the rotary movement of the type-wheel is such as to bring each alternate column of type into the printing position, and in order that the intermediate columns o f type may be brought into the printing position an additional electro - magnetic mechanism is provided which acts to shift the type-wheel when a prolonged current i mpulse follows the short current impulses for controlling the escapement mechanisms. The printing-mechanism is brought into action by the cessation of the short-current impulses, and also by the prolonged current which is necessary in certain cases. A special form of type-wheel escapement mechanism is described, the actuating- spring being rewound after the printing of each letter. The type-wheel 5, Figs. 1 and 7, is mounted to slide on and rotate with the triangular spindle 6, which is rotated by bevel-gearing 8, 9 from the shaft 10 having a spring-controlled yielding connexion 11, 12 with the shaft 13 of the escapement mechanism. The bevelwheel 9 is mounted to slide on and rotate with the shaft 10, so that rotation of this shaft will be imparted to the typewheel in any position of the carriage 7. The typewheel is mounted on a plate 57 supported by a rack 58 which gears with a pinion 59 sliding on and rotating with the shaft 60, yieldingly connected to the shaft 62 of a second escapement mechanism similar to the first. The rotation of the shaft 60 thus controls the height to which the typewheel is raised. The escapement mechanism, Figs. 1,4, and 5, comprises two escapement wheels 18, 19, the former fixed to a short shaft 30 and having a slot 22 through which extends a pin 20 on the loosely-mounted wheel 19. A ratchet-wheel 32 on the shaft 30 is engaged by a pawl 31<a> pivoted to the end of the shaft 13. The force of the spring 17 exerted on the shaft 13 through the pinion 14 locks the shaft to the escapement wheels, but a turning-force in opposition to the spring carries the pawl 31<a> over the teeth of the ratchetwheel 32. An extension 23 of the armature of the magnet 24, Fig. 12, normally engages the wheel 18, but the movement of the armature causes the extension to engage the wheel 19, thus allowing the shaft 13 to turn through one step. The driving- spring 17 is automatically rewound after each letter is printed by the rack 28, Fig. 1, which is raised by a spring-mounted vertical rod 36 every time the lever 34 is rocked by a cam on the printing-shaft 4. This movement also effects the return of the typewheel shaft to its zero position. The type-wheel correction-device for precisely adjusting the typewheel either about or along its axis consists of a star-wheel 39, Fig. 7, which is engaged by a spring- mounted plunger 40 when the standard 43 is moved to the right by the rocking of the shaft 46, effected by a cam on the printing-shaft 4. V-shaped notches in the standard 43 are provided at points corresponding to the vertical positions of the typewheel to engage the wedge-shaped end of the plunger 40. The type-wheel carriage is fed from left to right for letter-spacing by the worm shaft 38 and bevel-gearing 83, 84, 86, 87, Figs. 1 and 7, the shaft of the wheel 87 carrying a ratchet-wheel 88 which is moved forward one step by the pawl 91 each time the lever 89 is rocked by the pivoted lever 94 bearing on a cam on the printing-shaft 4. The worm shaft 38 is connected by gearing 98, 99 with a spring 100 which tends to rotate it in the opposite direction to effect the return of the typewheel carriage, but this is normally prevented by a pin 102 engaging the ratchet-wheel 88. To effect the return of the carriage, it is therefore necessary to raise both the pawl 91 and the pin 102. The lever 103, Fig. 7, carrying the pin 102, is pivoted at 104 and is provided with a pin 112 engaging the tail-piece 113 of the pawl 91, so that the rise of the end 105 of the lever 103 will completely free the ratchet-wheel 88. A pivoted lever 106 has its free end projecting under the lever 103 and is connected at 108 to a transverse lever 109, Figs. 3 and 7, which rides on a cam on the printing-shaft 4. A spring 111 is so connected to the lever 109 that the cam will normally cause the right-hand end of the lever to be raised, this having no effect on the lever 103. If, however, sufficient impulses are sent to line to raise the type-wheel one step above the lowest printing position, an arm on the shaft 60 that raises and lowers the type-wheel will engage the hooked end 125, Fig. 10, of the rod 123 and thus bring the notched lower end of the lever 120 above the right-hand end of the lever 109. When the shaft 4 next rotates, the right-hand end of the lever 109 will be unable to rise, with the result that the other end of the lever is raised, causing the lever 106, Fig. 7, to raise the lever 103 ; this releases the ratchet-wheel 88 and allows the spring 100 to return the type-wheel carriage. The end 105 of the lever 103 engages in a notch 117, Fig. 3, in the lever 114 until the carriage 7 is fully returned, when it strikes the lever 114 and releases the lever 103. A dash-pot 118, Fig. 1, prevents too much shock to the carriage 7 on its return. Line-spacing is effected on the return of the carriage by the ratchet-wheel 128 actuated by the link 129 connected to the lever 106. The platen 130, Fig. 7, is carried by the rock-shaft 132, which is connected by links 134, 135 to the lever 137 engaging a cam on the printing- shaft 4, Fig. 1. The link 135 is normally drawn upwards by the spring 136 and the rotation of the cam allows the spring to bring the platen into action. One or more blank spaces are left on the type-wheel so that when a space is needed in printing, the operator brings a space on the type-wheel to the printing position, whereupon the platen moves forward but the paper does not strike a type. In order that the type-wheel may be adjusted so as to bring the alternate columns of type into the printing position, the shaft 10, which effects the rotary movement of the type-wheel, is provided with a further ratchet-wheel 152, Fig. 10, operated by a pawl 150 pivoted to the bell-crank lever 148. The horizontal part of this lever normally rests on the extension 144 of the armature 141, Fig. 1, of the electro-magnet 140, but on each side of this point of engagement the lever 148, Fig. 10, is provided with two notches 154. A spring 155 tends to draw the lever 148 downwards, but this is normally prevented by the extension 144 and also by the rod 156 pivoted to a lever 157 which rides on a cam on the printing-shaft 4. This cam is cut away at a point so that it allows the spring to draw down the lever 148 just before the printing-platen comes into action. If at this moment the magnet 140 is energized and the extension 144 moved under either of the notches 154, the lever 148 will be rocked and will move the ratchet 152 one step, thus bringing one of the alternate columns of type into the printing position. A type on one of these alternate columns is thus brought into position by sending the necessary number of positive and negative impulses to actuate the escapement mechanisms to raise the type-wheel to the desired level, and to rotate it to the column following that in which the required type is situated. The last impulse is then prolonged, thus keeping the magnet 140 energized until the printing-shaft is set free, which then causes the ratchet-wheel 152 to move the type-wheel back one step before printing takes place. The printing- shaft is released both by the cessation of short impulses and also by the prolonged current sometimes required to position the type-wheel. To this end, the armature of the electro-magnet 140, Figs. 11 and 12, is connected by a bifurcated link 186 to the lever 183, adapted to close contacts 180, 182 or 179, 181, each of which is included in a local circuit containing the sluggish-acting magnet 166, Fig. 1, acting to release, and permit one revolution of, the printing - shaft 4. The springs 192, 193, Fig 11, normally keep the pins 187 on the lever 183 at opposite ends of the slots in the lever 186, so that a movement of the lever 186 in either direction causes the contact 179, 181 to be closed. The lever 183 is normally kept in the central position by the stud 189 on the lever 190, but when the first impulse is received by the magnet 140 this stud is released and the contact 179, 181 closed. As the line impulses are of short duration and are sent with great rapidity, the local circuit is not closed long enough to energize the magnet 166; but if a prolonged impulse is sent to line, the contact 179, 181 is kept closed and magnet 166 energized. On the other hand, if the line impulses cease, the spring 192 acts to close the contact 180, 182 and energize the same magnet. The rotation of the printing-shaft raises the lever 190 to engage the lever 183. The series of cams on the printing-shaft are so arranged that the series of operations effected by them take place in the desired order. The magnets controlling the typewheel escapement mechanisms are preferably of the Hughes type and polarized, being respectively de-energized by positive and negative impulses, which may be sent to line alternately.