Patent GB-1183171-A (GB)
Title: Printer
IPC: B41J33/36
Filed: 1968-01-08
Abstract: 1,183,171. Ink ribbon mechanisms. INTERNATIONAL BUSINESS MACHINES CORP. 8 Jan., 1968 [13 Jan., 1967], No. 1036/68. Heading B6F. An ink ribbon feed mechanism includes a gear train having a variable gear ratio which determines the extent of each increment of ribbon feed and which includes a portion movable as a consequence of supplying a cartridge containing a ribbon to the feed mechanism and operative in response to such movement to change the gear ratio. Feed mechanism.-The ink ribbon is driven from a main shaft through a cam-operated pawl (56), Fig. 3, not shown, engaging holes (57) in a ratchet wheel 58 which is keyed to a gear-wheel 63 by a spigot 69 engaging an aperture 70. A first rate of feed, for fabric ribbons, is obtained through gears 63, 74, 75, a shaft 76 rotatable with gear 75, a gear element 80 on which a projection 86 is engaged by a pin 84 on the shaft 76, and gears 87, 88 to drive a drive roller 40 having pointed projections 41 and which engages the outer turn of ink ribbon on a take-up spool, (Fig. 5, not shown). A second rate of feed, for plastics ribbons, is obtained by disengaging the pin 84 from the projection 86 by depression of the element 80, projections 94 thereon then coupling the element 80 to a gear 78 by engagement in holes 95. The drive is then obtained through gears 63, 74, 75, 96, 98, 78, gear element 80 and gears 87, 88. The gears 96, 98, 78 represent a gear reduction train which is permanently coupled to the drive input but selectively couplable with the drive roller 40. Ink ribbon cartridges.-An ink ribbon cartridge (10), Fig. 2, not shown, is adapted to fit on to the plate 27 carrying the feed mechanism, the drive roller 40 entering an arcuate slot (42) in the cartridge, the feed spool (16) being coupled to a spindle 35, and the take-up spool (24) sliding on to a spindle 39. To receive the cartridge, a lever 130 is turned counter-clockwise, this acting concurrently to move the drive roller 40 out of engagement with the ribbon on the take-up spool, to displace tensioning ribbon guides 110, 111 from ribbonengaging position, to disengage a pawl 123 from a rachet 124 and permit free rotation of the spindle 35 so that splines 38 thereon can engage splines (23), Fig. 4, not shown, on the feed spool (16), and to displace the ribbon lift guides (30, Fig. 2) to their highest position. The cartridge is formed with a recess (89) which is empty when a fabric ribbon is contained in the cartridge, but which houses a spring-loaded disc (91) when a plastics ribbon is in the cartridge. The recess (89) fits over the gear element 80 so that when the cartridge contains a plastics ribbon, the element 80 is depressed by the disc (91) and the slower rate of feed is automatically selected. Vibrator mechanism.-The ribbon lift guides (30) are lifted into operative position on each impression stroke by vibrator mechanism, (not shown) to an extent controlled by the ratchet wheel 58 through a cam follower (99, Fig. 3), engaging the contoured periphery of the wheel 58, so that successive throws of the vibrator mechanism vary. For stencilling, a lever 73 is turned so that the cam follower (99) engages a surface 174 to maintain the ribbon in its rest position. An arm 71 then prevents the pawl (56) from driving the wheel 58.