Patent GB-257657-A (GB)
Title: Improvements in or relating to typewriter ink-ribbon winding and automatic reversingmechanism
IPC: B41J33/516
Filed: 1925-06-02
Abstract: 257,657. Pateman, A., and Imperial Typewriter Co., Ltd. June 2, 1925. Ink-ribbon mechanism.-In automatic reversal mechanism for typewriter ink-ribbon feed mechanism, of the kind comprising a pivoted catch normally held out of the path of a rocking member actuated at each depression of a type key, the catch, instead of being positively operated by the tension in the ribbon, is released by means of a ribbon-controlled detent so that it drops by gravity or is moved by a yielding control, such as a spring, into co-operating position. As shown in Fig. 2, the ink-ribbon is being wound from the left-hand spool on to the righthand spool, the feed-pawl 9 and check-pawl 20 of the latter being secured to the hub of a loose sleeve on the shaft 1. The pawls 9 are pivoted at the outer ends 10 of levers which are freely pivoted at their centre on the shaft 1 and are rocked in unison at each depression of a type key, through a member 11 connected thereto. The inner ends 29 of the rocking levers are disposed in a plane below one arm 25 of a member 21 which is pivoted on the shaft 1 and is provided with five radial arms 22, 24 - - 27, the longest arm 22 of the left and right hand units being connected by a transverse link 23. The catch 280 is pivoted upon the arm 25 and is normally held in a raised position by the arm 32 of a forked lever 30 which is pivoted at 31 upon a fixed plate 8 and is attached to a spring 41, which holds the arm 32 in engagement with the end 38 of the catch. The other arm 33 of the lever 30 is arranged to be engaged in known manner by a projection 34 on a tongue 35 hinged to the hub of the ink-ribbon spool and extending through a slot in the lower flange. The outward movement of the tongue 35 of the exhausted spool turns the lever 30 about its axis to disgage the catch 280, the outer end of which drops through a slot in the arm 25 and is engaged by the co-operating arm 29 of the rocking lever at the next depression of a type-key, causing the arm 25, together with the other arms of the member 21, to swing about the shaft 1 in an anti-clockwise direction. The feed and check pawls are controlled by the arm 27 of the member 21, which carries a pin 28 engaging a slot 19 in the arm 18 of a T-shaped lever 13 pivoted at 14 to a bottom plate 2, the other arms 15, 16 of the lever 13 being respectively provided with projecting pins 12, 17 which hold the feed-pawl 9 and check-pawl 20 out of engagement with the ratchet wheel 5 while the ink ribbon is being unwound. The movement of the arm 27 when the spool is exhausted swings the lever 13 clockwise, allowing the pawls to engage the ratchet wheel for rewinding the ink-ribbon. At the same time the members of the right-hand unit are operated through the link 23 and member 21 to turn the lever 13 clockwise to disengage the pawls 9, 20 on that side. The left-hand unit is provided with a spring-controlled lever 43 carrying a loose roller 44 upon a pin 45, and co-operating in known manner with the arm 24 of the member 21 to complete the movement of the latter in either the clockwise or counterclockwise direction. An adjustable cam-stop 47 is provided to limit the movement of the feeding-pawls 9 to that of one tooth of the ratchet, wheel. If necessary, the movement of one unit relatively to the other may be regulated by an adjustable eccentric connection between the link 23 and the arms 22 of the members 21.