Patent GB-673131-A (GB)
Title: Ribbon guiding and feeding mechanisms for typewriting or similar machines
IPC: B41J3/24
Filed: 1949-11-25
Abstract: 673,131. Typewriters &c. TRIGGS, W. W. (Underwood Corporation). Nov. 25, 1949, No. 30307/49. Class 100 (iv). An ink-ribbon guiding and feeding arrangement, particularly for hectograph ribbons, comprises supply and take-up spools 47, 90, Figs. 1, 2, mounted on the machine framework and feeding the ribbon to and from the carriage for travel along the printing line, those portions of the ribbon extending from the supply spool 47 to the leading edge of the carriage and from the trailing edge of the carriage to the take-up spool being located in a plane parallel to the plane of the carriage movement. The mechanism operates so that the ribbon 55 remains stationary at the printing point during all carriage movements not caused by a type action e.g. tabulating, back-spacing, word spacing &c. and on the other hand the ribbon 55 moves bodily with the carriage during all letter-feed carriage movements so that an unused area of ribbon is brought to the printing point. The unused ribbon is supplied from the spool 47, Fig. 2, freely rotating on a sleeve 48 fixed to the framework 49 and is led over a guide roll 56 from where it forms an " approach span " to a feed roll 64 mounted on the carriage, the direction of travel of the ribbon being in the same direction as the letter-spacing of the carriage. From roll 64 the ribbon 55 extends across the rear of the carriage to a turning bar 71, over idler rolls 73, 77 to a front guide 78 from where the ribbon extends across the typing line along the platen 33 to similar guides and rolls 81, 82, 83, 84, 85 to a " leaving span '' in which the ribbon again extends in a letter-spacing direction to a guide roll 89. The ribbon is taken up by the spool 90 frictionally driven by a shaft extending through the sleeve 48 and driven by a friction drive 95, 91, 92 from a motor drive 22, over-running of the ribbon being prevented by a braking device acting on the perimeter of the supply spool 47. Mounted on shafts 65 and 86 of the rolls 64 and 85 are a pair of rolls 101, 102 over which travels an endless band 100 which passes through a clamping device 103 attached to the machine framework and normally preventing movement of the band so that for all carriage movements other than letter-spacing the. movement of the carriage which moves the shafts 65 and 86 laterally left or right as the case may be, causes them to rotate. Rotation of the feed rollers 64, 85 causes a movement of the ribbon relative to the carriage exactly proportional thereto so that the next unused portion of the ribbon 55 adjacent to the typing position remains stationary ready for the next type action. Upon the initiation of a' type action by the usual power mechanism 25-32, Fig. 1, the tail portion 36 of the lever 30 engages a bail 34 rocking a lever 38 carrying a pin 39 coacting with a cam surface 42 of a lever 40 which is turned clockwise drawing downwardly a link 45 having a connection 46a to the usual ribbon vibrator mechanism. Each time the link 45 is moved downwardly a pin 115 projecting therefrom closes contacts 113 which energise an electromagnet 109 which attracts its armature 110 connected to the lower jaw 108 of the clamp 103 and thus releases the belt 100. At the same time an extension 116 of the armature 110 pivots a lever 117, Fig. 10, and disconnects a pawl 60 from a ratchet 59 attached to the guide roll 56. When a letter-space carriage movement now takes place the band 100 travels bodily therewith and no rotation of feed rolls 64, 85 takes place and the release of the ratchet 59 allows the slack in the " leaving span " to be taken up by the spool 90 and a corresponding amount released from the spool 47 into the " approach span." No movement of the ribbon takes place along the typing line as an unused portion of the ribbon is presented to the typing position by virtue of the carriage movement. Ribbon travel is positively prevented by the action of a friction shoe 120, Fig 7, engaging the band 100 as it passes over the roller 101, the shoe being operated by an electromagnet 119 in parallel with the magnet 109. Alternatively the electromagnet 119 may cause a detent attached to its armature to engage in a toothed wheel on the shaft 65, such wheel having teeth equivalent to each letter space or a proportion of each space in the case of a variable letter-space machine. The ribbon 55 may be moved to inoperative position to condition the machine for use as a conventional typewriter by the operation of a lever 143, Fig. 10, which when moved from a notch 145 to a notch 146 allows arms 79, 80, carrying the guides 77, 78, 81, 82, to be pulled down by springs 138 so moving the ribbon 55 to the outer side of a paper guide 151. The arms are mounted on a connecting tube 76 sliding through a transversely fixed bail 153 having a depending ear 154 engaging a bell crank 156, so that when the arms 79, 80 are moved to disable the ribbon 55 the crank 156 engages a pair of contacts 114 which break the operating circuit of the magnet 109 and the roller feeding arrangement is ineffective. The rolls 64, 85 are preferably circumferentially lined with a soft, rubber-like material and the ribbon is frictionally coupled to roll 64 by a spring mounted pressure roll.