CA1144885A - Ribbon tensioning means - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An improved ribbon cartridge for use in electronic type-writers is disclosed. It features a foam pad mounted between the wall of the ribbon-containing cartridge and an incrementally driven ribbon capstan for urging the ribbon into good frictional contact with a frictional surface on the capstan for wiping the ribbon clean and damping the motion of the ribbon as it is driven forward.

Description

1 This invention relates to an improvement in t~ping

2 ribbon cartridges of the type wherein a capstan is used to

3 drive an inked typing ribbon from a supply reel into a posi-

4 tion juxtaposed with a character element so that the ink may

5 be deposited on a paper. More specifically, the invention

6 relates to a means for supplying tension to the tape whereby

7 i~ is held against the drive capstan so that excess ink and

8 contaminants are removed from the ribbon and whereby the

9 ribbon i9 not wasted due to over supply of ribbon require

10 ments.

11 In a particular machine which is sold by the

12 assignee of the present invention, an in~ed ribbon is pulled

13 off a spool in a disposable cartridge mounted on the frame

14 of a typewriter, passed through a flexible leader, past the

15 print point by means of a ribbon locating structure, and

16 passed through a second flexible leader back to a take-up

17 spool, mounted concentrically with the supply spool, within

18 the body of the cartridge. The drive o the ribbon to and

19 from the cartridge is controlled by means of a stepper motor

20 which increments the position of the ribbon one step with

21 each key stroke. The stepper motor on the typewriter drives

22 the ribbon ahead through a capstan in frictional engagement

23 with the substrate of the ribbon. If ribbon is not to be

24 wasted, it is necessary that the incremental advance of the

25 ribbon provided by the stepper be implemented by good fric-

26 tional contact between the capstan and the ribbon so that

27 no ribbon need be wasted. Since the cost of ribbon is a

28 primary element of cost-per-character calculations, it is

29 incumbent upon the manufacturer of replacement cartridges

30 to ensure that as little ribbon is advanced with each in-

31 cremental motion of the capstan as will permit proper print-

32 ing of characters.

33 Therefore, it has been found desirable to provide

34 means fox damping the motion of the supply spool so that

35 when the capstan is energized by the stepper motor the spool

36 rotates only so far as necessary to supply the amount of 4~5 1 ribbon called for and no further. This has worked well for 2 damping the incremental advance but has caused other prob-3 lems. Specifically, with heavily inked multi-strike ribbons, 4 ink from the inked side of the ri~bon has a tendency to be 5 deposited on the non-inked side of the substrate as it is ~ in contact therewith while the ribbon is wound upon the 7 supply spool. This ink then tends to be deposited on the $ friction surface of the capstan which in some cases can lead 9 to slippage between capstan and ribbon. As the capstan must 10 provide sufficient force to overcome the damping force pro-11 vided by the damping means, any decrease in the friction 12 between the substrate and the capstan will be made more 13 critical by the additional force necessary to overcome the 14 damping force. It would therefore be desirable to limit the 15 amount of force required to provide damping, thus simplifying 16 and making less critical the interaction of capstan and 17 ribbon.
18 It is an o~ject of the invention to provide a 19 ribbon movement damping means which performs its function 20 adequately but which does not introduce a great deal of fric-21 tional damping force into the mechanism.
22 It is a further obiect of the invention to provide 23 a cartridge in which the motion of ribbon is damped while 24 requiring minimal force to supply the ribbon.
Finally, it is an object of the invention to provide 26 an improved printing mechanism of the type comprising an 27 inked ribbon cartridge.
28 According to the present invention, a cartridge is 29 provided with damping for the ribbon by interposing a com-30 paratively small portion of a resilient foam material between 31 the cartridge and the capstan itself. This foam provides the 32 triple function of removing excess ink and any contamination 33 Erom the ribbon, of urging the substrate of the ribbon into 34 engagement with a friction surface on the capstan, and of 35 providing damping or the ribbon so that it is not overly 36 moved by the incremental motion of the capstan.

In one aspect of the present invention, there is provided in a printing machine of the type having character element means for being impacted into a ribbon at a print location for producing a mark on a medium corresponding to a particular one of said character elements, a ribbon supply assembly comprising: a cartridge: a reel of substantially flat printing ribbon mounted within said cartridge;
means, including an incrementally driven capstan in engagement with said ribbon, for incrementally withdrawing said ribbon from said reel to provide a corresponding incremental ribbon movernent at said print location; and means, including a resilient foam material pad mounted within said cartridge adjacent said capstan for urging said ribbon into engagement with a surface on said capstan and for damping the incremental motion of said ribbon at said capstan~
In a further aspect of the present i.nvention, there is provided an improved ribbon supply assembly comprising~ a substanti-ally flat ribbon in reel form; a cartridge enclosing said reel of ribbon; means, including an incrementally driven capstan in fric-tional engagement with said ribbon, for incrementally withdrawing said ribbon from said reel, and means, including a resilient foarn pad, for engaging a flat surface of said ribbon, for urging said ribbon into engagement with a frictional surface on said capstan and for damping incremental motion of said ribbon at said capstan by the force exerted thereon by said foam pad.

-2a-~4~5 1 The invention will be better understood if refer-2 ence is made to th~ accompanying dxawing, in which:
3 Fig. 1 represents an overview of the cartridge of 4 the invention in its intended environment, i.e. a type-S writer;
6 ~ig. 2 rPpresents an enlarged perspective view of 7 the cartridge including its leader means and ribbon lo-8 cator means;
9 Fig. 3 represents a plan view of the interior of the cartridge including the foam pad according to the in-11 vention;
12 Fig. 4 is a cross-sectional view of the cartridge 13 taken along the line 4-4 in Fig. 3;
14 Fig. 5 represents a schematic view of the supply reel of ribbon, capstan, the foam pad and the wall of the 16 tape; and 17 Figs. 6 and 7 represent cross-sectional views taken 18 along the line 6-6 in Fig. 5 of several types of foam pads 19 and capstans according to the invention.
Referring now to Fi~. 1 a typewriter comprises a 21 keyboard 10 which controls the motion of a print wheel 12 22 which comprises a plurality of spo~es having character 23 elements formed at their ends and adapted to be impacted 24 by a hammer 14 in order to drive a selected character element against a platen 16 over which a sheet of paper 18 26 may be interposed. A print ribbon 20 is interposed between 27 the character element 12 and the paper 18 so as to leave 28 an inked impression corresponding to the character ele-29 ments selected. In operation, the ri~bon 20 is raised by lifter means (not shown~ when the hammer 14 is about to 31 impact the character element 12. The ribbon 20 is carried 32 by locator means 180 which is provided with an uplifted 33 portion 181 under which ~he hammer and character element 34 may pass on their way to the paper 18. The locator means 180 is mounted by means of posts 44 on a moving carriage 36 22 desirably driven by a linear stepper motor 26. The ~, ....

s 1 ribbon 20 is then passed through flexible leaders 34 and 2 36 which are connected in turn to a ribbon cartridge 28 3 which is mounted within a receptacle 30. In this way, 4 when the carriage 22 moves back and ~orth with respect to the frame of the t~pewriter and the paper 18, the flexible 6 leaders 34 and 36 permit the locating means 180 to move 7 with the carriage 22 while the cartridge 28 remains fixed, 8 the flexible leaders 34 and 36 providing the interconnec-9 tion therebetween.
There may also be mounted on carriage 22 an erase 11 ribbon 42 which may be supplied ~rom a reel 38 and taken 12 up by a second reel 40 and used to either overprint a 13 letter struck in error or to remove it, depending on the 14 type of ink supplied by the ribbon.
Referring now to Fig. 2, the cartridge 28 is con-16 nected to the flexible leader 200 by means of mounting 17 structure 231 and 230. Ribbon 20 is fed through first 18 flexible leader 200 to locator 180 and returns by means 19 of second flexible leader 200 back to cartridge 28.
Locator 180 comprises a central section spacing 21 ends 188 arld 187 apart. These ends are adapted to mate 22 with corresponding piecas of leader 20. The ends 187 23 and 188 are provided with shaped notches 183 which engage 24 posts 184 ~hich are mounted on the carriage 22 of the typewriter and are, as discussed above, lifted when typ-26 ing is performed so as to interpose the ribbon 20 between 27 a selected character element and paper 18. A raised cen-28 tral portion 181 of the locator 180 is provided so that 29 the hammer 14 and character element 12 may pass there-through on their way to impact the paper. Desirably, the 31 ends 187, 188 of the locator 180 are provided with fingers 32 182 which may be operated by the operator when changing 33 ribbons in order to open notches 183 so as to disengage 34 from posts 184.
Re~erring now to Figs. 3 and 4, internal details .
.~,~,~

1 of the cartridge 28 are shown. The ribbon 20 is unwound 2 from a supply reel 60 by means of a capstan 70 which is 3 desirably driven by a stepper motor mounted on the type-4 writer ~not shown). Ribb~n 20 then passes around two guide posts 98, over a roller 100, and exits the cartridge 6 28 by means of leader mounting structure 231 and leader 7 200, thence to pass to the print point. APter ~eing typed 8 upon, the ribbon 20 is returned again via leader 200 and 9 leader mounting structure 230 over a post 102 and onto a take-up reel 64. Said supply and take-up reels 60 and 64, 11 respectively, ~which in a preferred embodiment are flange-12 less coils of ribbon) are mounted concentrically on a hub 13 62 and are both driven by means of the steppex motor, not 14 shown, acting on capstan 70. However, while the capstan 70 directly pulls on the ribbon 20 to supply it, the take-16 up 64 is driven by means of an intermediaty O-ring 80 and 17 a star wheel i6 which is provided with teeth 78 which en-18 gage the typed-upon ribbon as it is wound onto the take-19 up reel 64. Said O-ring may desirably be passed over an intermediate pully 92 which may be arranged so as to exert 21 an inward tension (i.e. a tension acting toward the hub 62) 22 on the arm 86 pivoted at 9D on which the star wheel 76 is 23 mounted so as to keep the star wheel in engagement with 24 take-up reel 64. It is desirable to make the star wheel 76 by an integral molding process, whereby a plastic wheel 26 is formed around a stamped metal star; in this way, an 27 effective and unitary construction may be formed simply 28 and inexpensively.. It will be observed from Fig. 4 that 29 the capstan 70 is shown as comprising a recilient band around its lower circumference which drives the inked 31 ribbon. In some circumstances, it is desirable to form 32 this tire integrally with the capstan 70 by means of an 33 integral molding process. In other cases, a resilient 34 band of the proper size may be slipped over the capstan 70.

.~

s 1 Referring now to Fig. 5, a schematic view is shown of 2 the ribbon 20 being passad off the hub 62 of the supply reel.
3 The ribbon 20 is then passed over capstan 70 which, as dis-4 cussed above, is driven by a stepper motor. A friction 5 surface 202 engaged the non-inked surface of the ribbon 201 6 and pulls it off supply reel 62; the ribbon 20 is then fed 7 to the remainder of the mechanism as shown and discussed 8 above in connection with Fig. 3. A foam pad 95 is inter~ i g posed between the wall of the cartridge 28 and the inked 10 side 203 of the ribbon 20.
li This interposition of a pad ~etween a wall of the car-12 tridge 28 and the inked side 203 of the ribbon 20 forces 13 certain limitations in the design of such a ribbon. For 14 example, certain ribbons are now in common use which are 15 of the "lift-off" type. These are designed to be used in 16 conjunction with an erase tape of the type which removes 17 the ink from the paper rather than overprinting it with a 18 second ink of a color designed to match that of the paper 19 (an "overprint" ribbon). With such a li~t-off ribbon, the 20 ink is so loosely attached to the substrate that the wiping 21 action provided by a foam pad 95 would be far too rigorous 22 for the ink to survive such a passage. Hence, the present 23 invention is not designed for use with a so-called lift-off 24 type tape since the tape is simply too fragile to allow 25 damping of the reel to be accomplished in this fashion. In-26 stead, foam pads are installed in the cartridges containing 27 such ribbon between the sides of the spool of tape 20 and .

1 the front or back wall of the cartridge 28. U.S. Patent 2 No. 4,079,827 to Work shows a similar arrangement. There-3 fore, the present invention is suitable only with tapes of 4 the overprint type whether they be of the single-strike or 5 multiple-strike class.
6 As discussed above, the interposition o~ a f~am pad 95 7 between the wall of the cartridge 28 and the ribbon 20 per-8 forms three distinct functions. Firstr any additional ink 9 which has accumulated on the ribbon 20 as well as any con-10 tamination is wiped off thereby. Second, the foam pad 95 11 presses the ribbon 20 into firm engage~ent with the resil-12 ient friction surface 202 of the capstan 70 so that it can 13 be driven thereby. Finally, the foam pad 95 provides a 14 damping mechanism for the ribbon 20 so that when the capstan 15 70 is incrementall~ moved under the action of the stepper 16 motor (not shown) the ribbon 20 does not tend to move any 17 further than necessary and hence is not wasted; thus ribbon 18 20 is used efficiently, and the cost per character of the 19 printing operation is reduced.
It will be apparent from a perusal of Fig. 5 that if the 21 ribbon were wound tightly as indicated in Fig. 3 rather 22 than loosely as shown schematically in Fig. 5, ink from the 23 inked side 203 of the ribbon 20 would tend to be deposited 24 on the uninked side 201 of the ribbon 20. This ink, being 25 largely carbonaceous or graphitic, tends to provide a slip-26 pery surface to all with which it comes into contact.
27 Specifically, friction surface 202 of the capstan 70 can 28 eventually become coated with this ink and if the demands 29 placed on it are too great or if it is not properly designed, 30 can slip, thus not advancing the ribbon 20 properly. For 31 example, in a previous arrangement it has been the practice 32 to provide a damping pad on the side of the supply reel 60 33 of ribbon 20, as discussed above in connection with a lift-34 off type of tape. Since in that case the foam was required 35 to provide sufficient damping force to damp the motion of 36 the entire spool 60 of tape, considerable force had to be 1 exerted thereon. According to the present invention, however, 2 only the motion of the small length of ribbon 20 being un-3 wound from the spool 60 need be damped, as the spool 60 it-4 self is permitted to free wheel. Therefore, a great deal 5 less force is re~uired ~o be imparted to the ribbon 20 by 6 the capstan 70 so that the effects of inking thereon become 7 much less critical. Further, the provision of the foam pad 8 between the capstan and the wall of the cartridge 28 forces 9 the ribbon into firmer engagement with the friction surface 10 202 of the capstan 70 than might otherwise be the case while 11 also providing adequate damping.
12 Referring now to Figs. 6 and 7, two distinct embodi-13 ments are shown in which a foam pad 95 is provided for the 1~ several functions listed above. In each case a capstan 70 15 being pivoted about an axis 69 under the influence of a 16 stepper motor (not shown) is provided with an inserted fric-17 tion surface 202 which in Fig. 6 is shown as an inserted 18 band of square cross~section which may desirably be made of 19 a resilient materlal such as rubber and in Fig.7 is a resilient 20 band of round cross-section of a similar material. Alterna 21 tives include forming a "tire" about that portion of the cap-22 stan 70 designed to contact the ribbon 20; the tire may be 23 integrally molded according to well-known techniques. Still 24 a further possibility involves a flat cross-section band 2S such as a common rubber band; or alternatively, the entire 26 capstan 70 could be made out of a resilient friction mate-27 rial such as rubber. Furthermore, the foam pad 95, can, as 28 shown in Fig. 6, only contact the ribbon ~0, in which case 29 it would press the ribbon 20 into engagement with the cap-30 stan 70 most effectively while providing damping force only 31 to the ribbon 20; whereas in Fig. 7 the foam pad is shown 32 contacting a portion of the capstan 70 as well. In this 33 case, while the foam would perform a friction engaging func-34 tion (that is, pressing the ribbon firmly against the fric-35 tion surface 202) it would perform the additonal function in s 1 the embodiment of Fig. 7 of also damping the motion of the 2 capstan 70 itself, which mignt in some circumstances prove 3 to be useful.
4 It has thus been shown how the placement of a foam pad 5 95 juxtaposed to the capstan of an inked ribbon cartridge 6 system can solve several problems at once. Placement of the 7 foam pad 95 between the wall of the cartridge or another 8 similar anchorage and the drive capstan 70 permis the damp-9 ing function of the foam pag 95 to be carried out with suit-10 able efficiency while not providing such a great force that 11 the friction required between driving capstan 70 and the 12 inked ribbon 20 itself is excessive and difficult to provide.
13 Further, the foam pad 95, placed as shown, increases the 14 probability that the frictional co~efficient between the 15 capstan 70 and the inked ribbon 20 will be sufficient by 16 firmly engaging the two together rather than depending on 17 the physical arrangement of the parts within the cartridge 18 28 for this function. While one skilled in the art will 19 appreciate that the preferred embodiment cartridge described 20 above with reference to Figs. 3 and 4 pulls the ribbon ahead 21 to some degree by its provision of a star wheel 76 driving 22 the rewind reel 64, nevertheless the provision of the stepper 23 motor driven capstan 70 is essential to proper feeding of 24 the ribbon 20, as otherwise the tension of the ribbon 20 may 25 vary. Control of ribbon tension is important; if tension is 26 excessi~e, the ribbon 20 may break, or be overprinted. If 27 insufficient tension is provided, i.e., if the ribbon 20 28 slips with respect to the capstan 70 the ribbon may tangle 29 and not wind up properly.
It will be appreciated by those skilled in the art that 31 numerous modiications and improvements can be made to the 32 invention as described without departing from its essential 33 scope. Specifically, the foam material chosen can be any 34 one of a wide variety of possible materials although in a 35 presently preferred embodiment a common plastic foam is pre-36 ferred. Further, different methods of assembling the car-1 tridge 28 according to the invention are possible. For 2 example, the foam 95 can be adhesively attached to an anchor-3 ing point, whether the side of the cartridge 28 or some other 4 point, in order to hold it in its proper position with re-5 spect to the ribbon 20 and capstan 70. Further, the cap-6 stan 70 itself could be driven by means other than by a 7 stepper motor mounted on the typewriter and indeed need not 8 even be a part of the cartridge 28 but could be mounted ex-9 ternally thereto. Even so, if a capstan 70 having a fric-10 tional surface 202 is to be used to engage the ribbon 20 and 11 impart to it a driving force, it is anticipated that the foam 12 pad 95 of the invention will find utility therein.

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. In a printing machine of the type having character element means for being impacted into a ribbon at a print loca-tion for producing a mark on a medium corresponding to a parti-cular one of said character elements, a ribbon supply assembly comprising: a cartridge: a reel of substantially flat print-ing ribbon mounted within said cartridge; means, including an incrementally driven capstan in engagement with said ribbon, for incrementally withdrawing said ribbon from said reel to provide a corresponding incremental ribbon movement at said print location; and means, including a resilient foam material pad mounted within said cartridge adjacent said capstan for urging said ribbon into engagement with a surface on said cap-stan and for damping the incremental motion of said ribbon at said capstan.

2. The machine of claim 1 wherein said capstan is mounted within said cartridge.

3. The machine of claim 2 wherein said resilient pad is attached to a wall of said cartridge between said reel and said capstan.

4. An improved ribbon supply assembly comprising: a substantially flat ribbon in reel form, a cartridge enclosing said reel of ribbon, means, including an incrementally driven capstan in frictional engagement with said ribbon, for incre-mentally withdrawing said ribbon from said reel; and means, including a resilient foam pad, for engaging a flat surface of said ribbon, for urging said ribbon into engagement with a frictional surface on said capstan and for damping incremental motion of said ribbon at said capstan by the force exerted thereon by said foam pad.

5. A ribbon supply assembly according to claim 4 wherein said capstan is mounted in said cartridge.

6. A ribbon supply assembly according to claim 5 wherein said resilient pad of foam material is attached to a wall of said cartridge between said reel and said capstan.

7. The assembly of claim 1 wherein at least a portion of said resilient pad is complementarily configured with res-pect to an opposing surface of said capstan, to thereby pro-vide an area of urged frictional engagement between said ribbon and said capstan.

8. The assembly of claim 7 wherein a generally circular portion of said capstan engages said ribbon, and wherein said resilient pad defines a generally arcuate surface which en-gages said ribbon.

9. The assembly of claim 1 wherein a portion of said resilient pad directly engages a surface of said capstan to directly damp movement of said capstan.

10. The assembly of claim 2 wherein said capstan comprises an annular projection for engaging a portion of the width of said ribbon and wherein said resilient pad engages and clamps the entire width of said ribbon.

11. The assembly of claim 3 wherein said resilient pad is formed of foam material and is interferingly disposed be-tween said capstan and an adjacent wall of said cartridge.