Patent GB-799956-A (GB)
Title: Improvements in or relating to telegraph printers
Inventor: HOWARD BERNARD
IPC: H04L17/26
Filed: 1956-02-06
Abstract: 799,956. Typewriters &c. TELEPRINTER CORPORATION. Feb. 6, 1956, No. 3647/56. Class 100(4) [Also in Group XL(b)] In a telegraph printer having a typecarrier connected by a cable to a plurality of pulleys selectively moved to determine the character to be printed, the pulleys are carried by levers engaged by associated cams which are selectively driven by a motor in accordance with the code elements of a signal. In the diagramatic arrangement, Fig. 23, in which the pulley arrangement is generally similar to that described in Specification 786,831, the type-carrier T has sixtyfour character spaces arranged in eight circumferentially arranged rows each comprising eight positions and the axial movement of the carrier is effected by a cable attached to a fixed post 48 and passing over three pulleys 28, 30, 32 carried by levers 20, 34, 36. The cable is connected via a controlling function plate 76 to a fixed post 50 by a pulley 38 connected by a bar 42 to a pulley 40 around which passes a cable 26 connected at one end to a drum 46 and passing through a hollow shaft 24 to a connection with the typecarrier T and to a restoring drum 44. The printing carriage 52 is connected by a cable 54 to the stepping drum 46 and also to a take-up drum 56 so that the type-carrier T and the printing carriage 52 are simultaneously traversed at every printing operation relative to the paper fixed platen. The rotational movement of the type-carrier is effected by a cable 58 passing round pulleys 64, 66 carried by levers 70, 72 and via a function plate 78 to a pulley 68 carried by a lever 74 and operable to rotate the shaft 24 through 180 degrees for the case shift operation. Detailed operation. When the start element is received, the armature 184 of magnet 1, Fig. 7, is rocked by a spring 186 so that the slotted end 190 of a lever 178 rotates a pivoted detent lever 183 to allow a main shaft 90 to be driven through half a revolution. by the motor M, the detent 183 being retained to the arresting position by cam 188. A gear 162 on the shaft 90 drives through gear 164 a shaft 166 carrying a number of sequentially disposed cams 168, Fig. 8, which control the sequential operation of the magnets 2-6 by the code elements on the received signal and the initiation of the printing operation. As shown in Fig. 8, the pulley 28 is carried by a yoke 116 secured to the cam follower lever 20 having a portion 122 engaging respectively, a. flat 126 or rounded portion of the cam which is secured between detent discs having proections connected with detent levers 16, 18 forming extensions of armatures 130, 140 operated by magnets 132, 144 provided in pairs for each of the pulleys 28, 30, 32, 64, 66. As indicated by the circuit arrangement, Fig. 22, the magnet 1 is released by movement of armature 154 by the start element and in response to each of the five code elements, one of the magnets of a pair indicated by 2, 3 or 6, is operated, the other being in the released condition. The sequential operation of the armatures to control the displacements of the pulleys is determined by the cam 168, and, in the case of the pulley 28 as shown in Fig. 8, if the magnet 132 is not energized, the recessed portion of the cam 168 allows the spring 134 to move the armature 130 upwardly so that the detent lever 16 is worked clear of the tooth 14 and the cam is rotated through a half a revolution to move lever 20 and pulley 28 to the left. During further rotation of the cam 168 the armatures 130, 140 are moved downwardly so that the cam 124 is retained in its position until the corresponding element of the next signal. If the magnet 144 had been in the released condition the upward movement of the armature 140 and rocking of the detent cam 18 would have had no effect. Printing and spacing operations. When the type-carrier T has been set the printing operation is effected by a hammer 196, Fig. 13, slidably mounted in a housing 210 which has flanges 211 sliding in grooves in a fixed member extending across the platen. The hammer is actuated by a bar 212 secured to arms 214 secured to a rotatable shaft 216 carrying an arm 218, Fig. 12, associated with a cam 220 secured to a disc 222 mounted on the shaft 90. When the pulleys have been operated, a sequence cam 234, Fig. 12, on the shaft 166 allows the lever 230 to move upwards and rock the arm 226 out of engagement with a projection 224 so that the cam 220 rotates through half a revolution and the sudden dropping of the arm 218 from the ledge 236 on the cam moves the bar 212 forward to impel the hammer 196 against the recording sheet 194 and the inking ribbon 200. At the same time, the rotation of the shaft 216 moves the pawl 250, Fig. 4, over a tooth of a ratchet wheel 246 secured to the drum 46 which is advanced by the return stroke of the shaft 216 and is held by a retaining pawl 252. Control of functions. The selection of functions, such as carriage-return, linefeed or case shift, is initiated by two plates 76, 78 which are slidable in guide members, are position by the movements of the pulleys 28, 30, 32 and 64, 66 and carry push buttons such as 262, 264 biased to their inoperative positions by springs When the pulleys have been moved in accordance with the code combination assigned to the function to be performed, the buttons will be in superposed relation and beneath an appropriate pusher member 266 which is moved downwardly when the shaft 216 is rocked for the printing operation and actuates a detent arm, such as 268, to allow an associated function cam, such as 309, to be driven from the shaft 90. Carriage return. The cam released by the carriage-return signal rocks a cam follower on a shaft connected to a torque tube 258 connected to the retaining pawl 252 carrying a pin 253 which lifts the driving pawl 250 so that the type-carrier T and carriage 52 are returned to their starting positions by their spring drums 44, 56. Line-feed. The rotation of the appropriate cam 294, Fig. 10, through one revolution allows the arm 286 and pawl 284 to move to the left under action, of a spring 288 and during the forward movement the ratchet 202 on the shaft of the platen roller is rotated to feed the paper. The detent lever, such as 268, Fig. 13, which controls line feed may have an extension 318 which can be operated manually to effect a continuous line-feed operation. Case-shift operations. For the figuresshift operation, a cam 309, Fig. 10, on the shaft 90 is permitted by a detent disc 308 to rotate through 180 degrees so that the cam follower arm 74 is moved to the position 74<SP>1</SP> and displaces the pulley 68 so that the type-carrier T is rotated through 180 degrees. For the return of the letters-shift position, a lever, such as 268, is operated to release a second detent disc 310 secured to the cam 309, which rotates through 180 degrees and allows the arm 74 to return to its right hand position in which the carrier T is restored to the letters-shift position. Ink-ribbon mechanism. The inking ribbon 200 is fed from a spool over guide members in a path parallel to the travel of the printing carriage and to a feed reel which is driven frictionally from the drum 56 and which feeds the used ribbon to the outside of the machine.