Patent GB-534299-A (GB)
Title: Improvements in or relating to ink-ribbon mechanism
IPC: B41J3/24
Filed: 1939-11-07
Abstract: 534,299. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 7, 1939, No. 29571. Convention date, Dec. 13, 1938. [Class 100 (iv)] Ink-ribbon mechanism.-In mechanism comprising a feed-device for an auxiliary ribbon operated by the carriage, and a guide-frame for moving the auxiliary ribbon into and out of the printing line, an automatic locking-device positively prevents feed of the auxiliary ribbon when the guide-frame is moved out of the printing line. The locking-device may also be operated during tabulating or when the carriage is moved to the left by hand. The apparatus shown in Figs. 2 and 3 is similar to that described in Specification 501,185 and comprises a casting 20 which is secured to the rear of the typewriter base 21 and supports a supply spool 37 and a take-up spool 40 for a hectograph ribbon 36. The take-up spool is coupled by a spring belt 89 to the continuously rotating power-roller of the typewriter. The casting supports also feedrollers 22, 42 and a spring-urged pressure roller 23 for the ribbon. The rollers are faced with cork or the like. A bail 59, pivoted at 60 to rear extensions 50 of the paper-carriage 45, supports guide-rollers 71a, 71b and pairs of turner-guides 74, 81 for directing the ribbon to and from the spools 40, 37 and along the printing line on the platen 51. The rollers are mounted on a bracket 73 which is secured to a tube 61 on the bail. Each guide 74 consists of a yoke 74a, a diagonally-arranged cylinder 75 having a guide-end plate 76, and a roller 78. Each guide 81 consists of a diagonally-arranged cylinder 82 having a guide-end plate 83, and guide-fingers 84, 84a. The fingers 84 and other guides 39, 39a, 73a are flared to prevent the ribbon-coating from being scraped off. Guide-rollers 79 are mounted on the bail 59 close to the guides 81. The ribbon is fed by means of a tape 85 which is connected at the ends to the bracket 73 and passes round a pulley 86 on the casting 20, and a pulley integral with the roller 22. A spring 85a connected to the bracket and tape maintains tension in the tape. During letter-spacing movement of the papercarriage, the roller 22 is rotated step-by-step by means of the tape, and the ribbon is fed off the supply-spool 37 without moving relatively to the paper-carriage, and is taken up and tensioned by the spool 40. When the paper-carriage is returned, the rollers 22, 42 are locked by cooperation of pawls 92, 93 with ratchet-wheels 29, 44 on the rollers, the tape slips, and the papercarriage moves relatively to the ribbon to bring a fresh length thereof into the printing line. The provision of the guide-rollers 71a, 71b for the tape, enables a casting 20 of only half the length of that described in the above-mentioned Specification to be employed. To prevent waste of ribbon means is provided for preventing feed of the ribbon when the paper-carriage makes a tabulating run, or is moved towards the left by hand, or when the ribbon is raised above the printing line. For these purposes, the escapement-release arm 57 when operated by the carriage-release levers or the tabulating-lever is arranged to move detents 96 into engagement with the ratchet-wheels 29, 44, and thereby lock the rollers 22, 42. For this purpose, the detents are coupled by links 97 to loose arms 98 on a shaft 99 provided with a fast arm 101 having a pin 102 engaging the arms 98, another fast arm 104 on the shaft being coupled to a link 105 which abuts on the arm 57. When the bail 59 is raised to move the ribbon out of the printing line, the arm 104 is rocked, to apply the detents 96, by means of a finger 125a on a block 124 slidable on a square shaft 120 which is mounted in the paper-carriage and is connected by links 121, 122 to the bail. The arm 104 is provided with a brake-block 126 for preventing the belt 89 from rotating the spool 40 when the rollers 22, 43 are locked by the pawls 96, or when the ribbon breaks or is removed. The bail 59 is raised or lowered, to move the ribbon into inoperative position, by means of a finger-piece 62 and is retained by springs 63, the upper position being determined by stops 50a. The lower position is determined by co-operation of studs 70 on the bail with flats 67b or recesses 67c formed in finger-levers 67 on a rock-shaft 66. When the flats 67b are in position, the bottom edge of the ribbon is at the printing line, and by interchanging the spools, the other edge can be employed; or by positioning the recesses 67c, the middle can be employed. The arrangement provides for maximum wear of the ribbon. Sheet-guiding arrangements.-A paper-bail 109, Fig. 3, pivoted on studs 111, on the paper-carriage 45, is provided with a lug 115 which co-operates with a lug 62a on the ribbon-bail 59 in such a manner that the paper-bail is raised when the ribbon-bail is raised, and if the paper-bail is depressed first, depression of the ribbon-bail and consequent damage of the ribbon are prevented.