Ribbon drive assembly for ribbon cartridge

A ribbon cartridge for use in impact type printers such as line printers, typewriters an, fie-dot printers. The ribbon cartridge includes a housing having a bottom wall portion, a re-inking assembly provided in a re-inking compartment within the housing for re-inking a ribbon, a ribbon storage compartment for storing the ribbon, and a ribbon drive assembly provided within the housing for advancing the ribbon. The ribbon drive assembly includes a toothed transfer-drive gear assembly and an idler gear assembly for engagement with the toothed transfer-drive gear assembly. In one embodiment of the present invention, the ribbon cartridge has a partition wall separating between the re-inking compartment and the ribbon storage compartment, and the toothed transfer-drive gear assembly has a vertical wall portion defining a part of the partition wall. A first engaging device is provided adjacent the partition wall and affixed to the bottom wall portion of the housing, and a second engaging device provided on the toothed transfer-drive gear assembly for removably engaging the first engaging device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to ribbon cartridges for use in impact type 
printers such as line printers, typewriters and wire-dot printers and more 
particularly to a ribbon drive assembly disposed within the cartridge and 
operative to drive the endless ribbon stored in the cartridge. 
2. Prior Art 
An impact type printer, such as a typewriter or a wire-dot printer, 
typically uses a ribbon cartridge storing therein an inked ribbon which is 
impregnated with ink. Typically, the supply of ink with which the ribbon 
is impregnated will be depleted long before the ribbon wears out. As the 
ribbon's supply of ink becomes depleted, print quality becomes 
increasingly lighter. The print quality finally becomes so light as to be 
unacceptable, and the ribbon cartridge must be discarded. 
A variety of re-inking assemblies have been proposed to re-ink the ribbon 
to thereby derive further use from the ribbon cartridge. A typical prior 
art re-inking assembly is mounted in the housing of the ribbon cartridge. 
The re-inking assembly has a re-inking roller which is formed from a 
porous material saturated with ink. A transfer roller is mounted for 
rotation tangentially to the re-inking roller. A ink ribbon drive assembly 
drives and advances an endless loop ribbon so that the ribbon is brought 
into contact with a portion of the transfer roller as it is advanced along 
its path. Ink is transferred from the re-inking roller to the transfer 
roller and then to the ribbon so that the ribbon is continuously re-inked. 
In a typical prior art ink ribbon cartridge, the ink ribbon drive assembly 
is mounted within the housing of the ink ribbon cartridge and has drive 
gear meshing with an idler gear. The drive gear and idler gear sandwich 
the ink ribbon therebetween and engage successive portions of the ribbon 
to move the ribbon along an endless path of travel and past a printing 
location located outside the housing where the ribbon is engaged by a 
printing mechanism. As the internal ink ribbon drive assembly advances the 
ink ribbon, the ink ribbon is fanfolded or "stuffed" into an ink ribbon 
storage area inside the cartridge housing. 
In one prior art, the ink cartridge housing has a top cover to allow the 
operator to readily access the inked ribbon, a re-inking assembly, and an 
ink ribbon drive assembly mounted in the ink cartridge housing. A drive 
gear is mounted on a bracket which is in turn removably mounted within the 
ink cartridge housing to facilitate maintenance of the inked ribbon, the 
re-inking assembly and the ink ribbon drive assembly. 
The ink ribbon cartridge is designed so that the bracket of the drive gear 
is somewhat retained between the top cover and the cartridge housing when 
the top cover is attached to the cartridge housing. Such a design results 
in various difficulties in the maintenance of the internal assemblies, 
such as replacement of the inked ribbon or other parts. For example, once 
the top cover is opened, it is difficult to close the top cover with the 
drive gear bracket in place. Sometimes, the drive gear bracket is lost 
during the maintenance work. 
SUMMARY OF THE INVENTION 
It is an object of the embodiments of the present invention to facilitate 
the maintenance of internal assemblies mounted within an ink ribbon 
cartridge. 
It is another object of the embodiments of the present invention to provide 
an improved ribbon drive assembly structure which is mounted with an ink 
ribbon cartridge. 
It is a further object of the embodiments of the present invention to 
provide a ribbon re-inking apparatus for use in a ribbon cartridge for 
printers. 
The above objects are accomplished by a unique structure for a ribbon drive 
assembly used in a ribbon cartridge, and the ribbon drive assembly 
includes a lock device to retain the ribbon drive assembly to the ribbon 
cartridge housing. More specifically, the ribbon cartridge includes a 
housing having a bottom wall portion, a re-inking assembly provided in a 
re-inking compartment inside the housing for re-inking a ribbon, a ribbon 
storage compartment for storing the ribbon, and a ribbon drive assembly 
provided within the housing for advancing the ribbon. The ribbon drive 
assembly includes a toothed transfer-drive gear assembly and an idler gear 
assembly for engagement with the toothed transfer-drive gear assembly. In 
addition, the ribbon cartridge has a partition wall separating between the 
re-inking compartment and the ribbon storage compartment, and the toothed 
transfer-drive gear assembly has a vertical wall portion defining a part 
of the partition wall. A first engaging device is provided adjacent the 
partition wall so as to project from the bottom wall of the housing, and a 
second engaging device is provided on the toothed transfer-drive gear 
assembly for removably engaging the first engaging device. 
Other objects, features, and advantages of the present invention will 
become apparent upon the reading the following specification when taken in 
conjunction with the accompanying drawings and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a ribbon cartridge in accordance with one embodiment of the 
present invention which is indicated generally at 10. 
The ribbon cartridge 10 comprises a casing formed of molded plastic or 
other suitable material, and the casing comprises a bottom housing 12 and 
a top cover 14. The top cover 14 is removably mounted to the top of the 
bottom housing 12. In the illustrated embodiment, the top cover 14 has 
side walls 16 which extend over side walls 18 of the bottom housing 12. 
Lock devices 19 are provided along the side walls 18 of the bottom housing 
12. As best shown in FIG. 2, the side wall 18 of the bottom housing 12 has 
an external surface 20 and an interior surface 22. Each lock device 19 
comprises a wedge-like protrusion 24 provided on the external surface 20 
of the side wall 18 and an opening 24 defined in the side wall 16 of the 
top cover 14. The wedge-like protrusion 24 has a curved shoulder portion 
28 and a downwardly facing edge portion 30. The opening 24 has an upwardly 
facing edge portion 32 which engages the downwardly facing edge portion 30 
when the top cover 14 is fitted on the bottom housing 12. 
As shown in FIGS. 3 and 4, the bottom housing 12 includes a ribbon storage 
compartment 34 for storing a ribbon 36 (not shown in FIG. 3). As best 
shown in FIG. 4, the ribbon 36 may be stuffed and stored in a plurality of 
loops. A ribbon drive assembly 38 is installed in the ribbon cartridge 10. 
The ribbon drive assembly 38 comprises a toothed transfer-drive gear 
assembly 40 and a toothed idle gear assembly 42 which engages the toothed 
transfer-drive gear assembly 40. The ribbon 36 is fed between the nip of 
the toothed transfer-drive gear assembly 40 and the toothed idle gear 
assembly 42 and advanced along its path into the ribbon storage 
compartment 34. 
The ribbon cartridge 10 is provided with a re-inking assembly 44 for 
re-inking the ribbon 36. The re-inking assembly 44 includes a re-inking 
roller assembly 46 and an ink-transfer roller assembly 48 which is 
positioned opposite the re-inking roller assembly 46. The ribbon 36, which 
is drawn into the interior of the cartridge housing, is positioned on the 
outer side of the transfer roller assembly 48 opposite the re-inking 
roller assembly 46, and extends to the nip of the toothed transfer-drive 
gear assembly 40 and the toothed idle gear assembly 42 of the ribbon drive 
assembly 30. 
As shown in FIG. 4, the toothed idle gear assembly 42, in accordance with 
one embodiment as shown in FIG. 4, includes a bracket 50 and an idle gear 
51 rotatably mounted on the bracket 50. The bracket 50 is pivotally 
mounted on a pin 52 extending from a bottom wall 12a of the bottom housing 
12. The bracket 50 is normally biased toward the toothed transfer-drive 
gear assembly 40 by a biasing device, such as a coil spring 54. 
Referring to FIGS. 4 through 7, the toothed transfer-drive gear assembly 40 
includes a bracket 56 and a drive gear 58 rotatably mounted on the bracket 
56. The drive gear 58 has a lower coupling extension 60 (see FIG. 7) which 
extends through an opening 62 (see FIG. 5) provided in the bottom wall 12a 
of the bottom housing 12. The lower coupling extension 60 engages an 
external drive mechanism of the printer (not shown) which rotates the 
drive gear 58. The bracket 56 has a substantially vertical wall 64 and a 
pair of columns 65a and 65b which are provided in the vertical wall 64 and 
spaced a distance from each other. The columns 65a and 65b define 
cylindrical bores 66a and 66b, respectively. 
A pair of posts 68a and 68b are spaced a distance from each other and 
extend from the bottom wall 12a of the bottom housing 12. The posts 68a 
and 68b engage the cylindrical bores 66a and 66b, respectively, to thereby 
guide the bracket 56 along the posts 68a and 68b as the bracket 56 is 
pushed downwardly. 
In accordance with one embodiment of the present invention, as seen in FIG. 
8, the bracket 56 includes a step-like beam portion 66 extending between 
the columns 65a and 65b. The beam portion 66 has an upwardly facing 
horizontal shoulder portion 68. On the other hand, a hook device 70, 
comprising a projection 72 provided with a hook 74, extends from the 
bottom wall 12a of the bottom housing 12. In a preferred embodiment, the 
projection 72 of the hook device 70 is flexible and can be flexed between 
an engaging position where a downwardly facing horizontal edge 76 of the 
hook 74 engages the upwardly facing shoulder portion 68 of the beam 
portion 66 and a disengaging position where the hook 74 disengages from 
the beam portion 66. Although the projection 72 is flexible, the 
projection 72 should have a sufficient degree of rigidity so that the hook 
74 does not readily or inadvertently come off the beam portion 66. When 
the toothed transfer-drive gear assembly 40 is desired to be removed from 
the hook device 70, the hook 74 may be flexed away from the beam portion 
66 with an appropriate tool or the like. 
Referring back to FIGS. 3 through 5, the re-inking assembly 44 is set in a 
re-inking assembly compartment 78 adjacent the ribbon storage compartment 
34. In the illustrated embodiment, the re-inking assembly compartment 78 
and the ribbon storage compartment 34 are separated by a partition wall 
80. 
In one embodiment of the present invention, the ribbon storage compartment 
34 is defined by two opposing parallel internal wall surfaces 82a and 82b, 
a side wall surface 84 which extends substantially perpendicular to the 
two opposing parallel internal wall surfaces 82a and 82b, and a diagonal 
internal wall surface 86 of the partition wall 80 which diagonally extends 
with respect to the two opposing parallel internal wall surfaces 82a and 
82b. Preferably, the internal walls 82a, 82b, 84 and 86 of the ribbon 
storage compartment 34 are generally flat and smooth to improve the 
movement of the ribbon 36 within the ribbon storage compartment 34. Also, 
since the lock devices 19 are provided on the exterior walls of the bottom 
housing 12, the internal walls of the storage compartment 34 do not have 
any portions protruding into the ribbon storage chamber 34. Furthermore, a 
corner 88 between the diagonal internal wall surface 86 and one of the 
parallel walls 82a is rounded. As a result, the movement of the ribbon 36 
within the ribbon storage compartment 34 is substantially smoothed out. In 
the illustrated embodiment, an internal wall surface 90 of the vertical 
wall portion 64 is continuous and flush with the diagonal internal wall 
surface 86 of the partition wall 80 and defines a part of the diagonal 
internal wall surface 86. In the illustrated embodiment, the columns 65a 
and 65b are provided on the vertical wall 64 of the transfer-drive gear 
assembly 40 so that the columns 65a and 65b are in the re-inking assembly 
compartment 78 and do not protrude into the ribbon storage compartment 34. 
It will be understood that modification of the present invention, in its 
various aspects, will be apparent to those skilled in the art, some being 
apparent only after study and others being matters of routine mechanical 
design. Therefore, the scope of the invention should not be limited by the 
particular embodiments herein described but should be defined only by the 
appended claims and equivalents thereof.