Patent GB-797665-A (GB)
Title: Improvements in teleprinters
Inventor: HANDLEY JOHN
IPC: H04L17/24
Filed: 1954-06-02
Abstract: 797,665. Ink-ribbon mechanism. CREED & CO., Ltd. May 27, 1955 [June 2, 1954], No. 16375/54. Addition to 794,093 [Group XL(b)]. Class 100(4) [Also in Group XL(b)] In a printing telegraph apparatus in which a type carrier is positioned by the aggregate motion of a number of levers under control of a number of cam followers permitted to become operative in response to the elements of a received signal or by members set from a keyboard and in which the cam followers are constantly urged by springs into operative relation with their cams to take up any backlash in the aggregate motion mechanism, the selective positioning of the type carrier from the aggregate motion mechanism is effected through a rack and pinion mechanism and the pivot about which the type carrier is rocked to print a selected character on a platen is disposed so that its axis passes through the point on the pitch circle of said pinion at which engagement is made with the pitch line of the said rack. The rotational setting of the type carrier 4 is effected by levers 1, 2, 3 controlled by cams and associated cam followers linked to summation rockers 61, 62 connected by links 63, 64 to the end 69 of cross arm 71 which can move about its other end 70. The centre connection 72 of arm 71 is fastened to the end of one arm of a bell crank 5, the other arm of which carries a rack 6 which, through pinions 7, 8 shaft 9 and bevel gears (not shown) rotates the type-wheel 4. The operation of a fourth link 12 via rocker 66 and link 67 connected to the end 70 of arm 71 moves the rack in reverse direction to impart to the type-wheel 4 a reverse rotation of 180 degrees. The type-wheel 4 carries four rings of types and the vertical movement to select the appropriate ring is effected by links 13, 14 associated with rockers 73, 75 connected by a link 77 to one arm of a bell crank 15 moving a rack 16 rotating pinions 17 and 18, shaft 19 and a pinion 20 meshing with a vertical rack 21 on the carriage of the type-wheel 4. The links 1, 2, 3, 12, 13 and 14 are connected to cam followers constantly urged to follow the contours of their respective cams by springs, such as 78, 79. For printing, a cam 22 lifts a rocker 23 and an arm 24 rocks a frame 25 on pivots 26, 27. In the arrangement described, the engagement of the pitch line of the rack 6 with the pitch circle of the gear 7 is on the axis of the pivots 26, 27 so that, arising from the printing stroke, no rotation is transmitted to the gear 7. Similarly, the point of engagement of the pitch line of the rack 16 with the pitch circle of the gear 17 is arranged to be on the axis joining the pivots 26, 27. Ribbon-feeding and reversing mechanism. The ribbon passes from a spool 44 over a roller 46 through a rocker 47, around guide members, back through the rocker 47 and over roller 50 to the spool 45. The letter spacing movement rocks a pawl engaging a ratchet wheel 35 connected to a sleeve 40 provided with a flange 60 and a rod 43 carrying an extension 43<SP>1</SP> with flange portions 43<SP>11</SP> urging outwardly one of two rings of balls 41 to effect driving engagement of a sleeve connected to the ratchet 35 with the hub 42 of one or the other of the spools 44, 45. When a spool is empty, an eyelet on the ribbon rotates the rocker 47 and a connected toothed member 51 which engages a fixed toothed member 53 and carries a slotted arm 54 in engagement with one arm 56 connected by a bar 56<SP>1</SP> with a second arm 56 coacting with a detent spring 71. The arms 56 carry inwardlyprojecting pins engaging between the flange 60 and the ratchet wheel 35, and clockwise movement of the rocker frame 56, 56 moves the extension 43 to the left so that left-hand ring of balls 41 connects the spool 45 to the sleeve driven by the ratchet 35.