Ribbon tensioning for a cartridge with flexible guides

A stuffed ribbon cartridge for a serial impact printer includes flexible leaders for guiding the ribbon from a stationary storage position to a movable print point. In order to place tension on the ribbon which is stored in the cartridge in a stuffed condition, a clip which pinches the ribbon so as to produce a drag force on the ribbon is located adjacent the print point and spaced from the cartridge by a substantial length of the flexible leader.

BACKGROUND OF THE INVENTION 
This invention relates to impact printers and, more particularly, to impact 
printers where a ribbon moves between a ribbon storage area and a print 
point to continuously supply fresh ribbon to a position between a 
character element and a print receiving medium. 
Copending applications Ser. Nos. 833,257, filed Sept. 14, 1977 and 
abandoned in favor of copending application Ser. No. 98,773, filed Nov. 
30, 1979, Ser. No. 833,270, filed Sept. 14, 1977, Ser. No. 833,269, filed 
Sept. 14, 1977, now abandoned and Ser. No. 873,714, filed Jan. 30, 1978, 
now abandoned disclose ribbon cartridges for impact printers which include 
flexible leaders or guides which guide the ribbon from the stationary 
storage area within the cartridge housing to a movable print point. By 
utilizing the flexible leaders so as to permit the storage area to remain 
stationary, it is possible to store much larger amounts of ribbon within 
the cartridge without affecting performance of the printer since the 
carriage for the printing mechanism need not move the stored ribbon, but 
merely that portion of the ribbon which is guided to the print point by 
the flexible leaders. Since a large amount of ribbon may be stored within 
the cartridge, the operator of the printer is not required to change the 
cartridge as often and thus avoids the risk of defacing the print 
receiving medium during replacement of the cartridge, e.g., smearing may 
be avoided. In addition, the use of a cartridge capable of substantial 
ribbon storage is more cost-efficient when one considers that the 
cartridge is, in effect, disposable. In other words, where the capacity 
for ribbon storage is quite large, the ratio of the cartridge mechanism 
cost to the ribbon is reduced and the overall cost of the cartridge per 
strike is decreased. 
In the cartridges disclosed in the aforesaid application, the ribbon is 
stored on reels. The supply reel stores the ribbon prior to passage past 
the print point and the takeup reel stores the ribbon after passage from 
the print point. By driving the take-up reel, some control on the tension 
of the ribbon may be obtained. In this connection, it will be understood 
that the tension on the ribbon is important, particularly when flexible 
leaders are utilized, in order to assure that the ribbon remains taut at 
the print point while at the same time not creating excessive drag on the 
ribbon through the leaders. 
In a stuffed ribbon cartridge, there may be no reels or at most one reel 
and control on the tension of the ribbon becomes more problematic. If a 
drag is placed on the supply of ribbon within the cartridge, that drag is 
magnified through the length of the leaders and can adversely affect the 
performance of the cartridge. In this regard, it will be understood that 
it is important that the ribbon move relatively freely through the long 
flexible leaders between the storage area and the print point for proper 
operation of the cartridge and the printer. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of this invention to provide a means by which 
tension can be placed on the ribbon of a cartridge employing long flexible 
leaders without affecting the performance or operation of the cartridge. 
It is a further object of this invention to supply such a means for 
creating tension which is adapted for use with cartridges employing long 
flexible leaders where the ribbon is stuffed in the storage area. 
In accordance with these and other objects of the invention, tensioning 
means are provided which are spaced from the ribbon storage area by a 
substantial length of the flexible ribbon guide. 
The cartridge may include a bridge adapted to support the ribbon at the 
print point and the tensioning means may be coupled to the bridge. In the 
preferred embodiment of the invention, the tensioning means comprises 
pinching means in the form of a removable clip including a finger adapted 
to rub on the ribbon. The pinching means may include a convex surface 
adapted to cooperate with the finger so as to pinch the ribbon.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1, a ribbon storage area 10 is formed within a housing 12 
which is closed by a cover 14. Ribbon 16 leaves the cartridge through a 
flexible leader 18 attached to the cartridge at blocks 20 and moves to a 
print point 22 at the center of a bridge 24. The ribbon 16 is then 
returned to the cartridge through a flexible leader 26 which is attached 
to the housing 12 at blocks 28. 
In accordance with this invention, tension is maintained on the ribbon 16 
by applying a drag force at area 30 which is spaced from housing 12 of the 
cartridge by a substantial length of the flexible leader 18. More 
particularly, the drag force which creates the tension is achieved by a 
removable clip 32 which includes a finger 34 cooperating with a convex 
surface 36 so as to pinch the ribbon between the surface 36 and the finger 
34. 
Referring to FIG. 3, it will be seen that the clip 32 includes opposing 
grooves 38 and flanges 40 which are adapted to capture the edges of 
section 42 of supports 44 of the bridge 24. However, a channel 46 as best 
shown in FIG. 4 is provided so as to permit the ribbon 16 to move between 
the section 42 and the clip 32 to the area of pinching contact between the 
finger 34 and the convex surface 36. 
As also shown in FIG. 3, the bridge 24 includes support slots 48 which are 
positioned immediately behind convex surface 36. The slot 48 is open and 
closed during mounting of the bridge 24 on a printer by pinching arms 50 
toward one another as depicted by arrows 52. As shown in FIG. 1, similar 
arms 50 and a slot 48 are located at the other end of the bridge 24. 
As also shown in FIG. 3, the end of the flexible leader 18 is retained by a 
fastener 54 located at the end of the segment 42. A similar fastener 54 is 
provided for the other leader 26 as shown in FIG. 1. 
In order to more fully understand the nature of the drag force applied by 
the clip 32, reference will now be made to FIGS. 4-7. As shown in FIG. 7, 
the ribbon 16 moves through a passage 56 of the flexible leader 18 
relatively freely, i.e., there is room between the ribbon 16 and the 
boundaries of the passage 56 which is formed by a cross-curved steel 
member 58, which is disclosed in detail in the aforesaid application Ser. 
No. 833,257 which is incorporated herein by reference, and an elastic 
sleeve 60 which covers the steel 58 but because of the cross-curved nature 
of the steel 58 leaves the passageway 56. It will, therefore, be 
appreciated that relatively little drag force is applied to the ribbon 16 
by the leader 18 or the leader 26 which is of similar construction. 
After the ribbon 16 leaves the leader 18, the ribbon 16 moves through the 
passageway 46 of the clip 32 as shown in FIG. 5. Here again the ribbon 16 
is not restrained, i.e., there is space on both sides of the ribbon 16 
within the passageway 46 so as to permit free movement of the ribbon 16 
therethrough. 
The ribbon 16 then moves into the region between the finger 34 and the 
concave surface 36 as shown in FIG. 6. Here, a substantial drag is 
effected by the pinching between the finger 34 and the surface 36. 
Reference will now be made to FIG. 2 for a more detailed description of the 
cartridge housing 12. As shown in FIG. 2, the ribbon 16 is stored within 
the housing 12 in a stuffed fashion within walls 58. The stuffing is 
accomplished by means of sprockets 60 which are located in one corner of 
the housing 12. One of the sprockets 60 is coupled to a gear 62 which is 
driven by a suitable motor. In order to assure that the sprockets 60 
appropriately grip the ribbon 16, the other sprocket 60 is mounted so as 
to idle in a bracket 64 which is biased toward the other sprocket 60 by a 
spring 66. An additional sprocket 68 is also mounted on the bracket 64 
which guides the ribbon 16 into the space between the sprockets 60. Guides 
70 are secured to the housing 12 adjacent the sprockets 60 so as to 
confine the stuffed ribbon 16 within the housing 12 between the walls 58. 
A similar guide 72 is provided at the top of the housing 14 where the 
ribbon 16 emerges from the stuffed storage area 74 and moves toward the 
leader 18 after undergoing a 90.degree. twist at a guide 76 within the 
housing 12. A similar twist occurs when the ribbon 16 enters the housing 
12 from the leader 26 adjacent a post 78. 
Although a specific embodiment of the invention has been shown and 
described, it will be understood that other embodiments and modifications 
will occur to those skilled in the art. For example, it may be desirable 
to utilize the tensioning mechanism of this invention in cartridges which 
are not of the stuffed type, i.e., such a tensioning mechanism may be 
utilized in a reel type cartridge. In addition, it will be understood that 
such a tensioning mechanism is particularly advantageous in connection 
with a cartridge having flexible leaders for guiding the ribbon to and 
from a stationary position to a movable print point. In this regard, it 
will be appreciatd that the specific nature of the flexible leaders may 
vary. See, for example, the aforesaid copending application Ser. No. 
833,257 which is again incorporated herein by reference. See also the 
aforesaid application Ser. No. 833,270 for a description of a printer 
incorporating a stationary cartridge which is incorporated herein by 
reference as well as copending application Ser. No. 61,879 filed July 30, 
1979 for its disclosure of a bridge 24 in such a printer which is 
incorporated herein by reference. 
As used herein, the phrase flexible leaders is not limited to leaders of 
uniform flexibility. By way of example without limitation, a flexible 
leader need not be uniformly flexible as shown and described in the 
foregoing specification. The leader could be, for example, articulated and 
substantially rigid between points of articulation so as to be flexible 
overall. 
Although a specific embodiment of the invention has been shown and 
described and various modifications suggested, other modifications and 
embodiments will occur to those skilled in the art which will fall within 
the true spirit and scope of the invention as set forth in the appended 
claims.