Patent GB-597637-A (GB)
Title: Printing telegraph apparatus
IPC: H04L17/24
Filed: 1944-07-31
Abstract: 597,637. Type-printing telegraphy. TELETYPE CORPORATION. July 31, 1944, No. 14575. Convention date, July 29, 1943. [Class 40 (iii)] Printing telegraph apparatus comprising a signal responsive selector which controls a mechanism for printing characters and in addition a mechanism for perforating a web to control the transmission of signals incorporates a back-spacing device which effects back spacing in both the printing and perforating mechanisms. The arrangement is preferably such that the printing mechanism is not affected by perforation of the tape corresponding to a case-shift combination and the keyboard may be locked against normal operation until the back-spaced characters have been deleted or rubbed out. General operation. The invention is described as applied to a page printer as disclosed in Specification 524,342 in which a platen 18 is moved relative to a type wheel 19 which can be displaced axially to bring the selected row of type into printing position and which is moved after the printing operation so that the printed character is visible. The signal impulses applied to a selector magnet 35 (Fig. 1) control a sword-and-T mechanism, indicated generally at 33, to position selecting levers, one of which is shown at 36. The upper ends of the levers 36, Fig. 2, engage slots in a number of notched code discs co-operating with a number of stop pins 38, one of which falls into aligned notches to stop the type wheel at the appropriate printing position. Shaft 22 which carries the printing and spacing cams is driven by gear 27 and carries a box cam 54 co-operating with a roller 56 mounted on a lever 57 rotatable on a shaft 58. A lever 59 mounted on shaft 58 and secured at its forward end to the bell-crank 57 is used for effecting prescribed functions dependent on predetermined positions of the type wheel. A number of pins 25 disposed in different radial and axial positions on the type-wheel shaft co-operate with a number of superposed levers 63 pivoted on a pin 64a carried at the rear end of the lever 59 to provide functional operations such as case shift, carriage return, &c. when the appropriate lever 63 is blocked by the corresponding pin 25 and is rocked about an intermediate pivot point. The spacing lever 64 is connected through a pin 68 and slot 66 to a bell-crank 60 actuated by a cam (not shown), a spring 67 surrounding the pin 68 taking up the motion imparted by the cam when the forward end of the lever 64 is blocked. A prong 69 on the lever 64 engages the spacing ratchet 71 which through a gear steps the platen against the action of a spring which is employed to effect carriage return. A pawl 75 biassed by a spring 77 co-operates with the ratchet 71 to hold the carriage in position. Perforating mechanism. The setting of' the levers 36 is transferred to the perforating mechanism by pivoted levers 82. A lever 51 provided with a locking extension 52 rotates the levers 82 counter-clockwise by means of projections 85 and according to the positions of the ends 87 of the levers 36, the levers 82 are selectively retained in their anticlockwise positions and place pivoted interponents 84 in their right-hand position with punch heads 94 above punch pins 89. A punch hammer 95 pivoted at 96 and operated by a cam on shaft 23 through levers 97, 98 engages a member 105 carrying the interponents 84 so that the punch pins 89 arc operated to perforate the tape 93. A lever 101 pivoted at 99 and having a cam roller at one end carries at the other end a pawl 102 biassed by a spring to engage a ratchet 104 for feeding the tape. A star-wheel 108 mounted on the shaft 106 is associated with a detent jockey roller 109. Back spacing arrangements. Back spacing is effected by a lever 112 mounted in the punch block 111. The forward end of the lever is connected by links 126, 131 to the arm 132 of a lever 133 pivoted at 134 and having a slotted arm 135 engaging a pin 136' fixed to a pawl lever 137 which has an extension 138 arranged to release the pawl 69 on spacing lever 64. An extension 141 of pawl lever 137 engages a projection 142 on the pawl 75 and releases the ratchet wheel 71 and a tooth 144 on the slotted lever 135 is rotated into a position to limit the rotation of the wheel 71 to one step. The back spacing bar 112 carries a plate 117 rotatably mounted on a screw 120, Fig. 3, and rotatable on the shaft 106. A triangular member pivoted on a shaft 119 carried by the plate 117 has a pawl 118 and a projection 121 which bears against the bar 112 so that during its operative movement, the member is rotated anticlockwise to bring the pawl 118 into engagement with the back-spacing ratchet 123. An arcuate member 124 carried by the plate 117 has a projection 125 which disengages pawl 102 from the ratchet 104 when the plate is moved in anticlockwise direction. The drum carrying the carriage return spring is provided with a projection which prevents the operation of the back-spacing lever 112 when the carriage is at the beginning of a line, Fig. 9 (not shown). Keyboard locking arrangement and "rub out " indicator. The keyboard may be locked against normal operation by the arrangement shown in Figs. 6, 7, 8 and 10. The star-wheel. 108 engages a toothed rack 302 slidable in a guide member 303 and having a groove 314 with an end wall 315 engaging a bracket 312 when the rack bar has been moved to its extreme right-hand position. A spring 316 attached to the guide member 303 holds the teeth of the rack bar 302 against the teeth of the wheel 108 for the reverse steps during the "rub-out" operation. A pivoted plate 319 carrying the instruction "rub-out" has a short lever 323 which is engaged by the top surface of the rack bar when it is moved one or more steps to the right and displays the warning instruction through the aperture 321. A disc 325 driven from the shaft 106 through a friction member 326 and spring 327 has a notch 329 engaged by a locking lever 331 when the disc 325 is in the position shown in Fig. 7 with the lug 345 in the position 350 in which the disc is held against rotation by a latching arm. When the star-wheel 108 rotates anticlockwise, the lever 331 is forced out of the notch and rotates a locking lever 336 so that its end latches a universal bar 338, which is normally operated by a key lever, such as 342, to actuate a link controlling the clutch of the transmitting mechanism. Modified back spacing arrangements. Figs. 11, 12, 13 show a modification in which the back-spacing step of the platen is suppressed on the occurrence of a case shift combination of perforations in the back-spaced tape. The perforating mechanism includes a sixth lever 154 connected to an interponent 152 associated with a sixth punch-pin 153. The bar 152 has an extension 155 lying across the bars 84 and provided with a rounded portion opposite the third bar and the arrangement is such that for the two shift combinations the interponent 152 is displaced to the right so that on the actuation of the hammer 163 a sixth perforation is made in the tape. The punch pin 153 is mounted in a separate member 159 which carries a detecting pin 168 and which is connected to the backspacing lever 167 through a pivoted rod 174. The member 159 is also connected to a pivoted lever 178 having an arm which in its counterclockwise position engages a collar on the lever 167. When the pin 168 engages a perforation in the tape, the lever 159 moves to the left, rotating the lever 178 so that its free end limits the movement of the back-spacing lever 167. If, however, there is no perforation opposite the pin 168, the movement of the lever 167 is not arrested and it engages the lever 182 which controls the back-spacing of the platen as described in connection with Fig. 2. The restricted movement of the lever 167 is arranged to be sufficient to back space the perforated tape. A further modification, Fig. 15, employs additional pins 212 to detect the code combination corresponding to the "Figures shift " or "Letters unshift" combination. The pins are mounted in an arm 211 of a lever pivoted at 209 and having a screw arm 215 with adjustable screws 216, 217 which engage a recessed member 218 on the back spacing lever 219 and a latch member 221 pivoted at 223 on a lever 222 connected to the back spacing mechanism for the platen. When the pins 212 engage the perforations corresponding to a case shift signal, the lever arm 211 is rotated and on movement of the lever 219 the screw 216 falls into the recess 227 and the screw 217 rotates lever 221 so that the lever 222 is not actuated. The further movement of lever 219 causes the screw 216 to ride out of the recess and to withdraw the pins 212 from the tape. A frame member 241 attached to the lever 219 carries a pawl 232 which engages the backspacing ratchet 234 and a pivoted lever 237 which engages a projection 238 to remove the pawl 202 from the tape feeding ratchet. In a further modification, Figs. 20 to 23 (not shown), and somewhat similar to the arrangement described in connection with Fig. 15, sensing pins are employed to control a pivoted latch member so that the back-spacing operation is not applied to the platen when a case shift combination appears on the back-spaced tape. Additional locking and other features. Further features comprise the locking of the keyboard against normal operation until the type-wheel has been returned to the upper case position if it was in that position at the initiation of the back-spacing operation, Figs. 24, 25 (not shown), the provision of a stamp for printing a "rubout " mark on the back-spaced perforations, Figs. 26, 27 (not shown), or a casing containing a lamp shining through an aperture to indicate when all the back-spaced signal combinations have been deleted or rubbed out, Figs. 28, 29 (not shown). The feeding mechanism for the perforated tape may be disconnected by a slidable lever 391, Figs. 2, 3, carrying an indicator 395 and having a projection 392 wh