Patent GB-692110-A (GB)
Title: Improvements in multicopy attachments for typewriting machines
IPC: B41J35/30
Filed: 1950-11-08
Abstract: 692,110. Ink-ribbon mechanism. HENRY, B. L. Nov. 8, 1950 [Nov. 8, 1949], No. 27315/50. Class 100(iv) Duplicating arrangements; ribbon shields and guides.-A duplicating ink-ribbon attachment for removably fitting to one end of a reciprocating carriage of 'a typewriting machine comprises a frame pivotally mounted so that a duplicating ribbon carried thereby can be swung from an operative position where it lies along the printing line to an inoperative upward position substantially at right-angles to the carriage. The frame comprises a head section 18' consisting of a duplicating- ribbon housing 34 and the ribbon advancing mechanism 102, a cross-bar 19, an outer end 117 adjustably supporting the left-hand end of a pair of ribbon guides 20, 21 extending along .the printing line behind the normal ribbon, and a spring latch 116 which securely fixes the attachment in use position shown. The ribbon guides 20, 21, Fig. 15, are formed from thin sheet metal (approx..003 inch) of flattened tubular shape and have slots 26, 27, cut therein so that longitudinal grooves, 131, 132 thereby formed, guide the ribbon 24 across the printing line and back along the same line so that two undercopies may be typed. In a modification the guides are formed from strip metal of sufficient thickness to prevent smudging of copy sheets D, E. F, G, by the ribbons 24 as they are advanced for line-spacing. Each stretch of ribbon 24 rests on edges of the cut-out slots and a pair of bands surround the guides at each end to hold the ribbon in the slots. To facilitate the threading of papers into the attachment the guides of each embodiment are automatically separated when the attachment is raised to the dotted position, Fig. 2, since the right-hand end of the guide 21 is fixed to a spring latch 52, Fig. 4, pivoted at 53 on the head section 18. Fig. 10 shows the position of the latch with the attachment raised. When lowered a stop on the frame engages a surface 129 moving the latch into the position shown on Fig. 4. The latch 52 may also be moved axially on the pivot 53 to tension the guides 20, 21 by a thumb-nut 135. The head section 18 is fixed on a bracket 136, Fig. 4, pivoted at 29 between pintles 30 on a plate 31 attachable to the carriage of any standard typewriting machine. The attachment is held in raised position against a stop-lug 172, Fig. 16 (not shown), on the bracket 136 by means of a torsion spring 106. As shown in Fig. 15 the attachment accommodates a top copy C with the normal ink-ribbon 13 and four copies D-G, two with normal image and two with mirror image. When it is required to provide only a single carbon copy a masking strip is detachably secured to the forward ribbon guide-21 and the copy is inserted behind the rearmost guide i.e. the G position. Ribbon feeding arrangements.-The duplicating ribbon 24 travels between two spools 40, 41 within the housing 34 and is guided through one of the guides 20, 21 across the printing position around a post 56 holding the left-hand end of the guides 20, 21 and returns through the second guide back to the housing through the spring latch 52. The spools are advanced by a shaft 62, Fig. 4, carrying a ratchet wheel 101 advanced unidirectionally by a pawl 104 attached to a pulley 103 which is rotated by a tape 99 each time the carriage is moved in a carriage return direction. This feeds the ribbon 24 and winds up the torsion spring 106 within the pulley 103 which rewinds the tape 99 on the spool 103 during character spacing. A pawl 105 attached to the housing 34 prevents rotation of ratchet 101 during this movement so that the' ribbon is stationary relative to the attachment. Automatic reversing arrangements.-The driving shaft 62 terminates in a pawl-holding disc 65, Fig. 7, comprising two half-sections 63, 64 screwed together at 72. A shaft 61 attached to section 64 extends through a bayonet connection to a handrotatable knob 68, Fig. 4. The disc 65 is slotted to carry a pawl 73, Fig. 6, which is urged in either direction by a snap-over spring 85 passing through a slot 86 in the pawl and anchored in notches 87. In operation the drive from shaft 62 is transmitted to either of the spools 40, 41 by gears 35, 36 respectively which engage pinions 59, 60 rotating on shafts 62, 61 coupled to outer discs 57, 58 having lugs 94, 95 projecting inwardly to be engaged by the pawl 73 according to its position. When the rotation of one disc, say 57, is prevented due to exhaustion of the ribbon, the continued rotation of the pawl 73 causes its end 92 to be urged inwardly through its slot 75 by the lug 94 and the pawl 73 eventually snaps into the dotted position, Fig. 6, where the drive is transmitted to the other disc 58. Ribbon connections.-The ends of the ribbon 24 are secured to the spools 40, 41 by a semicylindrical spring 151, Fig. 20, gripping the ribbon to a metallic sleeve 150 on the spools. A cap having prongs 154 frictionally engages in the notches 152 and holds the spring 151 in place.