Patent GB-483618-A (GB)
Title: Improvements in or relating to printing telegraph apparatus
IPC: H04L17/00
Filed: 1937-06-25
Abstract: 483,618. Type-printing telegraphy. CREED & CO., Ltd., and POTTS, L. M. June 26, 1937, No. 17727. Convention date, Aug. 5, 1936. [Class 40 (iii)] [Also in Group XVI] In combined transmitting and receiving apparatus which prints both received and transmitted signals, these signals are differentiated by the use of a two-colour ink-ribbon operated by a shift lever having projections which limit its movement in the case of received signals, the abutment to the projections being removed by a cam operated by the transmitter shaft so that the lever is moved to a greater extent to bring a differently coloured part of the ribbon into action. Provision is made for case-shift movements of the ribbon. General operation of printing mechanism. The printer is substantially as described in U.S.A. Specification 1,904,164 with modified ink ribbon control, the type carriage being movable transversely on guides 29, 31 and the platen 55 movable vertically for case shift. The type bars 54 are operated through rack and pinion gearing by pull-bars 51 selected by combs 24 carried by levers 23 actuated by vanes 22 selectively operated in response to received signals, or locally by a keyboard transmitter. The carriage is traversed by a rack 37 and gearing 36, 34 driven by the main shaft 19 which also carries a cam 45 engaged by a lever 42 having an adjustable abutment 46 normally holding the printing bail 41 in the position shown against the action of spring 43. The bail 41 carries transverse bars 47 engaging a roller 48 on the pull-bar bail 49 which partakes of the transverse movement of the carriage. To effect printing, cam 45 releases lever 42 so that printing bail 41 is moved counterclockwise and carries bail 49 to the left so that projection 53 engages and operates the selected pull-bar 51 which has dropped into the slots in the combs 24. Transmitting mechanism. This is generally similar to that described in U.S.A. Specification 1,595,472. Depression of a keylever causes the transmitting shaft carrying cains 81, Fig. 3 to be clutched to a driving shaft 21, and the Key-levers control code bars 84 which cause levers 82 to hold or release, according to the signal to be transmitted, goose-neck levers 79 which control the transmitting contacts in conjunction with the cams 81. The cam shaft is geared to a shaft 91 carrying a face-cam 78, Fig. 2, for controlling the position of the ink ribbon guide during transmission as will appear later. Ink ribbon control : case shaft. The ribbon 56 is carried in a guide 57 controlled by bellcrank lever 58 which is moved clockwise by a spring 112 when pull-bar bail 49 is moved to the left to effect printing, the ribbon being thus moved up to the printing position and restored by bail 49 after printing to enable the printed character to be read. When the machine is operating as a receiver a feathered bar 71, extending transversely of and mounted on bearings in the fixed frame of the machine, is in the position shown so that the horizontal arm of bell-crank 104 supports the end of a pivoted arm 107 in a position in which it lies in the path of the upper of a pair of lateral projections 109, 114 on the downwardly extending arm of bell-crank 58 thereby limiting the clockwise movement of 58 so that the ribbon guide 57 is lifted only enough to bring the upper colour area of the ribbon into the printing position. When, however, the machine is transmitting, face-cam 78, driven by the transmitter, moves bar 97 to the right whereupon lever 101 rocks feathered bar 71 into the clockwise position so that bell-crank 104 is moved counterclockwise. Arm 107 is thus allowed to drop clear of projection 109 and bell-crank 58 is moved clockwise to the full extent permitted by bail 49 and the lower colour area of the ribbon is presented 'for printing. The lever 58 is pivoted on a spring controlled lever 61 pivoted at 62 to the type carriage and carrying a roller 65 which is urged against a rail 66 on the platen carrier so that when the platen is raised for case shift, lever 61 follows and raises ribbon guide control lever into a position in which the lower lateral projection 114 is engaged by arm 107 to limit the movement of the lever 58 and ribbon guide 57 when the machine is receiving. The bar 71 is locked in the clockwise position independent of the transmitter shaft by a spring actuated detent 116 which is tripped by a spring-controlled arm 122 on the printing bail 41 when the bail returns to normal after' printing.