EP0008681B1 - Inking ribbon cartridge - Google Patents

Abstract

A replaceable cartridge containing an endless loop ink ribbon for use in printing units. The ribbon storage area inside of the cartridge is configured to guide the ribbon so that a large amount of ribbon may be stored in the allowed space while retaining favorable ribbon feed characteristics. The ribbon is guided by ledges formed on the inside surfaces of the cartridge between the ribbon inlet and outlet openings. The cartridge is to be constructed in halves and is designed with such symmetry that the halves are identical and so may be produced by the same tool or machine.

Description

The invention relates to an exchangeable ink ribbon cassette for printing units, comprising a housing with an essentially rectangular storage space enclosed by a bottom surface, a cover surface parallel to this and by side walls running between an inlet end and an outlet end of the housing for receiving an endless ink ribbon passing between a pair of transport rollers on the inlet side in a multiplicity of freely formable loops, the distance between the top and bottom surfaces being slightly larger than the width of the ink ribbon and with thresholds arranged at opposite points of the top surface and the bottom surface near the outlet end transversely to the general direction of flow of the ink ribbon through the storage space are whose distance from each other is less than the width of the ribbon.

Such ink ribbon cassettes can be inserted into the ink ribbon device for printing units, the part of the endless ink ribbon located outside the ink ribbon cassette running through the printing unit and pulled out of the ink ribbon cassette at the outlet opening by means of suitable transport devices and inserted into the ink ribbon cassette at the inlet opening to form the loops.

In general, the ribbon cassettes of this type have the task of accommodating as many ribbon loops as possible in the storage space in order to achieve the longest possible service life of the ribbon cassette with a small space requirement for the ribbon cassette. However, the ribbon build-up pressure created by pressing a large length of ribbon into the storage space can make it difficult for the ribbon to be pulled out on the outlet side or that several ribbon loops are pulled out at the same time when the ribbon is pulled out of the outlet opening.

In order to avoid this difficulty, it has already been proposed in DE-A 25 34 535 to arrange the sleepers approximately in the middle between the inlet and outlet openings, so that the storage space is subdivided into an inlet space with a high belt pressure and an outlet room with a low belt pressure. If the belt back pressure in the inlet space exceeds a certain size, individual belt loops between the sleepers are pressed into the outlet space, in which they lie loosely, without exerting pressure on the outlet opening. This avoids the fact that several ribbon loops are pulled out of the outlet opening or snap out of it at the same time, but only a relatively small amount of ribbon can be accommodated in this ribbon cassette for a given volume of the same, since half of the storage space is of the exit space which absorbs only relatively few ribbon loops is formed.

Furthermore, it is known from DE-A 25 36 645 to divide the storage space into three spaces in succession with the aid of a plurality of thresholds, in which a gradual reduction in the band pressure toward the outlet opening takes place. This embodiment is not only more complicated, but also has the same disadvantages as the embodiment according to DE-A 25 34 535.

Finally, from DE-A 27 32 362 an interchangeable ribbon cassette is known, in which the ribbon can be stored on two rolls or in the form of a loop. Exclusively on the bottom surface of the ribbon cassette are thresholds running transversely to the side walls, which on the one hand serve as a support for the ribbon rolls and on the other hand serve to reduce the ribbon pressure when the ribbon is stored in the ribbon form in the ribbon cassette. In this case, however, the disadvantages described above also apply to this ribbon cassette. It should also be noted that the thresholds are interrupted and each have a slight distance from the side walls. By attaching the same to the bottom of the cassette, jamming of the ends of the tape loop cannot be prevented here either. Furthermore, the ribbon cassette according to DE-A-27 32 362 has on its inlet side ribbon retention and guide elements, each of which extends over a little less than half the width of the inlet end of the cassette housing and both circumferentially engage two transport rollers arranged inside the ribbon cassette , through whose nip the ribbon runs.

The invention has for its object to provide an easy to produce ribbon cassette of the generic type, which has a high volume storage capacity with a small volume and ensures trouble-free ribbon passage during operation.

This object is achieved in that the thresholds directed essentially perpendicular to the longitudinal side walls and substantially parallel to the exit gap between the transverse side walls that form each start from one of the two opposite longitudinal side walls and end at a distance from the other longitudinal side wall, so that a Avoid jamming of the tape loop ends located in these spacing areas and that at the entry-side end of each long side wall there is provided a band retaining and guiding element, each of which extends at a distance from the bottom surface and top surface substantially perpendicular to the respective long side wall over less than half the width of the open entry end of the housing and both engage in the cassette operating position on the two transport rollers arranged separately from the ribbon cassette on the circumference.

Many of the flat ribbon loops lie against one of the side walls of the housing with the loop bend. In the area of the loop bend the ribbon is stiffer than in the straight section of the loop, so that usually a larger pull would be required to pull the ribbon at this point between the two sleepers. With the solution according to the invention, the clear height of the storage space between the top and bottom surfaces is reduced by a threshold height in the immediate vicinity of each side wall, so that the passage of the ink ribbon is facilitated near each side wall and thus the stiffening effect of the loop bend plays no role. Due to the design of the points proposed according to the invention, it is possible to bring the strip windings close to the exit gap. As a result, the outer dimensions of the ribbon cassette essentially correspond to the actual ribbon storage space. The exit end of the ribbon cassette is extremely simple.

The conveyor rollers are located outside the ribbon cassette, which greatly reduces the manufacturing price of the ribbon cassette. The ribbon cassette only needs to be placed on the conveyor rollers so that the ribbon guide elements engage in grooves in the rollers. None of the roles need to be swung away for this. The tape guide elements are essentially between the cover plate and base plate, so that the risk of damage to these sensitive elements is greatly reduced. Because of this design, the ribbon cassette according to the invention is very simple in its construction and therefore inexpensive to manufacture.

In order to facilitate the sliding of the ink ribbon over the sleepers and to protect the ink ribbon, the sleepers preferably have a semicircular cross-sectional profile on the facing surfaces.

The transverse side walls ensure that several belt loops cannot be pulled out through the outlet opening at the same time, if for some reason several belt loops should cross the sleepers at the same time. The outlet gap between the transverse side walls is expediently made so wide that the ink ribbon can be pulled freely.

The ribbon retention and guide elements ensure that when the transport lock is removed from a new ribbon cassette, the ribbon loops in the ribbon cassette, which are under a relatively high backlog pressure, cannot snap out through the inlet opening. On the other hand, the entry opening is large enough to conveniently allow the tape to be stored in the storage space. In order to facilitate the storage of the ribbon into the ink ribbon cassette by means of a storage device, each ribbon retaining and guiding element preferably has a ribbon instruction area near its free end on the side facing the storage space. This prevents the ribbon from wrapping around the rollers, for example, when the ink ribbon is stored with the aid of the transport or conveyor rollers rolling against one another. Since the ribbon retaining and guiding elements are each at a distance from the bottom and top surfaces, they can engage in a circumferential annular groove in the rollers and thus ensure that the ribbon is detached from the rollers.

The top surface and the bottom surface preferably each protrude outward beyond the side walls. The part of the ribbon running outside the storage space between the outlet opening and the inlet opening, forming a Möbius loop, during the transport of the ink ribbon cassette can be accommodated in the space that is delimited on three sides and is open towards the outside.

In order to achieve the most uniform possible formation of the ribbon in the storage space and an unobstructed transport of the ribbon through the storage space, the latter is preferably designed such that its base area delimited by the side walls, the sleepers and the ribbon retention and guiding elements is essentially rectangular.

The housing is preferably essentially symmetrical both with respect to its vertical longitudinal center plane running perpendicular to the ceiling and floor surface in the middle between the side walls and with respect to a horizontal center plane running parallel to the ceiling and floor surface in the middle between these.

In order to simplify the manufacture of the housing and to facilitate the insertion of the ink ribbon into the housing, this preferably consists of at least two housing parts, one of which comprises the bottom surface and the other the top surface. Such a division facilitates, for example, the demolding of the housing parts when they are manufactured as injection molded parts. The assembly of the two housing parts after inserting the ribbon is particularly simple if the two housing parts can be connected to one another by plug-in connection elements are. In order to prevent the housing parts from unintentionally falling apart when handling the ink ribbon cassette and the strongly coloring ink ribbon leaving stains somewhere, the plug connection elements are preferably designed in such a way that the housing parts can be non-detachably locked together.

According to a particularly simple embodiment, each pair of mutually cooperating plug-in connection elements consists of a pin arranged on one housing part and a plug-in socket arranged on the respective other housing part for receiving the pin. The pin and socket can be designed so that they deform when they are brought together and prevent separation of the housing parts without destroying the housing. The production of the ribbon cassette according to the invention can be achieved particularly simply and inexpensively in that both housing parts are of identical design. If the housing is made, for example, from injection molded plastic parts, then a single mold is sufficient to produce both housing parts. An identical design of the housing parts is possible, for example, when the housing is divided in such a way that each of the housing parts has a side wall to the top or bottom surface and the part wall connected with this on the outlet side of the storage space and the band retention and - connected with this side wall. includes guide element.

• Figur 1 eine Draufsicht auf die neuerungsgemäßge Kassette mit schematisch angedeuteter Einspeichervorrichtung für das Farbband,
• Figur 2 eine Draufsicht auf eines der beiden identischen Gehäuseteile, aus denen die neuerungsgemäße Farbbandkassette besteht,
• Figur 3 einen Schnitt längs Linie 111-111 in Figur 2,
• Figur 4 einen Schnitt längs Linie IV-IV in Figur 2,
• Figur 5 einen Teilschnitt längs Linie V-V in Figur 1, und
• Figur 6 eine der Figur 1 entsprechende Draufsicht auf die neuerungsgemäße Farbbandkassette im Transportzustand.

Further features and advantages of the innovation result from the following description, which explains the innovation using an exemplary embodiment in conjunction with the accompanying figures. Show it

• FIG. 1 shows a top view of the cassette according to the innovation with a schematically indicated storage device for the ink ribbon,
• FIG. 2 shows a plan view of one of the two identical housing parts that make up the ink ribbon cassette according to the invention,
• FIG. 3 shows a section along line 111-111 in FIG. 2,
• FIG. 4 shows a section along line IV-IV in FIG. 2,
• 5 shows a partial section along line VV in Figure 1, and
• Figure 6 is a plan view corresponding to Figure 1 of the new ribbon cartridge in the transport state.

The ink ribbon cassette shown in FIG. 1 comprises a housing, generally designated 10, with a storage space 12 for receiving an endless ink ribbon 14, which is stored in the storage space 12 in a multiplicity of freely shaped ribbon loops 16. The ink ribbon 14 leaves the storage space 12 through an outlet opening 18 and is reintroduced into the storage space 12 through an inlet opening 20 by means of a storage or transport device, which is generally designated by 22. Between the outlet opening 18 and the inlet opening 20, the ink ribbon 14 passes through a printing unit (not shown), forming a Möbius loop.

The storage space 12 is delimited by a base plate 24 (FIG. 5), a cover plate 26 running parallel to this, side walls 28 which run essentially parallel to one another perpendicular to the base plate 24 and cover plate 26, and on the outlet side of the storage space 12 by two running between the base plate 24 and the cover plate 26, the gap-shaped outlet opening 18 between defining transverse walls 30. On the entry side, the storage space 12 is essentially open except for two band retaining and guiding elements 32, which are arranged at the entry-side end of each side wall 28 and each extend perpendicular to the respective side wall 28 over less than half the width of the storage space 12.

Near the upper end of the storage space 12 in FIG. 1 at a short distance from the transverse walls 30, a threshold or rib 34 is arranged both on the base plate 24 and on the cover plate 26, which is perpendicular to the side walls 28 at opposite points of the base plate 24 and the cover plate 26 extend transversely to the general conveying direction of the ink ribbon 14. While the distance between the base plate 24 and the cover plate 26 is somewhat larger than the width of the ink ribbon 14, the height of the sleepers 34 is dimensioned such that their mutual distance is significantly less than the width of the ink ribbon 14. They thus form an obstacle for the ribbon loops 16 pushed from the inlet opening 20 towards the outlet opening 18, at which the ribbon loops are stowed. This enables ribbon ribbons to be inserted into the storage space 12 with considerable pressure, so that a large amount of ribbon can be stored in the storage space 12 without the ribbon loops being pressed against the transverse walls 30 and clogging the outlet opening 18. If the belt back pressure becomes very large, the belt loop immediately adjacent to the two sleepers 34 is folded and pressed between the two sleepers 34, so that a single loop 16 lies in the space between the transverse walls 30 and the sleepers 34. This loop can then be easily pulled out of the outlet opening 18 without having to use a lot of force.

Even if the belt loop 16 lying directly on the sleepers 34 is not pushed through between the ribs 34 by the penetrating belt loops, it can nevertheless be applied with very little effort are pulled between the two ribs 34. In any case, this effort is much less than the pulling force that would be required to pull the ribbon out of the outlet opening 18 when the ribbon loops are immediately built up.

The sliding over of a ribbon loop over the sleepers 34 is facilitated in that they have a semicircular cross-sectional profile on the sides facing one another (FIG. 5). At the same time, this also protects the belt.

As can be seen in FIG. 3, each threshold 34 starts from one of the side walls 28 and extends only to the vicinity of the other side wall 28, the two thresholds 34 starting from the opposite side walls. As a result, in the immediate vicinity of the two side walls 28, the distance between base plate 24 and cover plate 26 is only reduced by one rib height. This also reduces the resistance opposite the ink ribbon through the thresholds 34. In most ribbon loops 16, the area with the smallest radius of curvature is located directly on one of the side walls 28. In this area, the ribbon is relatively stiff against buckling, so that greater resistance has to be overcome if the ribbon is pulled between the sleepers 34 want. However, since there is practically only one threshold in the immediate vicinity of the wall, this effect is compensated for. In order to prevent the ribbon from getting stuck on any sharp edges, the free end 36 of the respective threshold 34 is chamfered (FIG. 3).

The ribbon transport device 22 indicated in FIG. 1 comprises two transport rollers 38 and 40, between which the ribbon 14 runs. The ribbon retention and guiding elements are intended to prevent the ribbon 14 from wrapping around the transport rollers 38 or 40. At the same time, they should ensure that the ink ribbon 14 is properly inserted into the storage space 12, forming the ribbon loops 16. For this purpose, the elements 32 are designed in the manner shown in FIG. 4 so that they can engage in a circumferential groove 42 or 44 of the transport rollers 38 or 40. Near their free ends on the side facing the storage space 12, the elements 32 each have an instruction surface 46, the radius of curvature of which essentially corresponds to the radius of curvature of the respective transport roller.

If the cassette is in its transport position shown in FIG. 6, the elements 32 serve to hold an elastically flexible securing strip 48 which is inserted into the storage space 12 in the manner shown in FIG. 6 and lies in front of the inlet opening 20, so that the storage space 12 is essentially sealed by the security strip 48. This prevents ribbon ribbons from falling out of the storage space 12 during the transport of the ribbon cassette and drying of the color of the ribbon during longer storage times. If, on the other hand, the security strip 48 is pulled out of the storage space 12 immediately before the ribbon cassette is used, the elements 32 prevent the ribbon loops 16, which are under a certain dynamic pressure, from snapping out of the storage space.

As can be seen in the figures, the base plate 24 and the cover plate 26 protrude somewhat beyond the side walls 28, so that a space which is delimited on three sides and is open to the outside is created. The piece of ink ribbon 14 running outside the storage space 12 between the outlet opening 18 and the inlet opening 20 is inserted into this space during transport, so that it cannot be damaged.

According to the invention, the housing shown in FIG. 1 consists of two housing parts 50, each of which comprises a bottom surface 24 or top surface 26, a side wall 28, a transverse wall 30, a band retaining and guiding element 32 and a rib 34. The two housing parts 50 are connected to one another by plug connection elements. For this purpose, each housing part 50 has a plug-in socket arranged on the side wall 28 near the end on the inlet side thereof and an insertion socket arranged at an angle between the side wall 28 and the transverse wall 30 for receiving a pin 54 arranged at a corresponding point on the other housing part 50. If the housing part 50 shown in FIG. 2 is rotated about a vertical axis lying in the plane of the drawing, so that the base plate or cover plate is at the top, and the housing part 50 thus arranged is placed on a further housing part 50 in the position shown in FIG. 2, as can be seen one that the housing shown in Fig. 1 can be produced. The extraordinary advantage of this design of the housing parts 50 is that only one tool is required for their production, which considerably reduces the production price of the ribbon cassette. The housing parts can thus be produced as simple injection molded parts from a preferably transparent plastic. After inserting the ribbon 14, the two housing parts are plugged together with the aid of the connector elements 52, 54 and pressed against each other. With a somewhat conical design of the pins 54 and a complementary conical shape of the recesses in the plug-in sockets 52, a firm connection between the two can be achieved by appropriate pressure on the two housing parts.

The new ribbon cassette is simple and inexpensive to manufacture and has a high tape storage capacity with small external dimensions.

Claims (8)

1. Replaceable colour-ribbon cassette for printing units, comprising a housing (10) with a substantially rectangular storage space (12) enclosed by a bottom surface (24), by a top surface (26) parallel to this latter and by side walls (28, 30) extending between an inlet end and an outlet end of the housing (10), this storage space serving to accommodate an endless colour-ribbon (14) passing through at the inlet side between a pair of feed rollers (38, 40) and in a plurality of freely formable loops (16), wherein the distance between top surface and bottom surface (26 and 24 respectively) is slightly greater than the width of the colour-ribbon (14) and wherein at mutually opposite places on the top surface (26) and bottom surface (24) near the outlet end there are arranged ridges (34) directed transversely to the general direction in which the colour-ribbon (14) passes through the storage space (12), the distance apart of which ridges is less than the width of the colour-ribbon (14), characterised in that the ridges (34), which are directed substantially perpendicular to the longitudinal side walls (28) and substantially parallel to the transverse side walls (30) forming therebetween an outlet gap (18), start from a respective one of the two opposite longitudinal side walls (28) and terminate at a distance from the respective other longitudinal side wall (28), so that any jamming of the ribbon-loop ends situated in these clearance zones is obviated, and in that at the inlet- side end of each longitudinal side wall (28) there is provided a ribbon-retaining and guiding element (32), each of which extends respectively at a distance from the bottom surface (24) and top surface (26) substantially perpendicular to the respective longitudinal side wall (28) over less than half the width of the open inlet end of the housing (10) and both of which engage, in the operating position of the cassette, peripherally on the two feed rollers (38 and 40) arranged separated from the colour-ribbon cassette.

2. Colour-ribbon cassette according to Claim 1, characterised in that each ribbon retaining and guiding element (32) has a ribbon-directing surface (46) near its free end on the side facing the storage space (12).

3. Colour-ribbon cassette according to Claim 1 or 2, characterised in that the top surface (26) and the bottom surface (24) project outwards over the longitudinal side walls (28).

4. Colour-ribbon cassette according to one of Claims 1 to 3, characterised in that the housing (10) is of substantially symmetrical design both in relation to a vertical longitudinal centre plane extending perpendicular to the top surface (26) and bottom surface (24) midway between the longitudinal side walls (28) and in relation to a horizontal centre plane extending parallel to the top surface (26) and bottom surface (24) midway between these latter.

5. Colour-ribbon cassette according to Claim 4, characterised in that the housing (10) consists of two identical housing parts (50) which respectively comprise one of the two basic surfaces (bottom surface 24, top surface 26), a longitudinal side wall (28) and the transverse side wall (30) continuous with this latter on the outlet side of the storage space (12), as well as the ribbon-retaining and guiding element (32) continuous with the longitudinal side wall (28).

6. Colour-ribbon cassette according to Claim 5, characterised in that both housing parts (50) can be undetachable connected to one another by plug-connection elements (52, 54).

7. Colour-ribbon cassette according to Claim 6, characterised in that each pair of mutually cooperating plug-connection elements has a plug (54) arranged on one of the housing parts (50) and an insertion socket (52) arranged on the respective other housing part (50) and for receiving the plug (54).

8. Colour-ribbon cassette according to one of Claims 1 to 7, characterised in that when the colour-ribbon cassette is not in use the housing (10) can be closed by an elastically flexible guard strip (48), the length of which amounts to more than twice the length of the storage space (12) and which is so inserted through the inlet end of the storage space (12) into the latter than with one of its ends, starting from the outlet-side end of one side wall (28), it extends along the inside, is applied with a curve against the free end of the ribbon-retaining and guiding elements (32) and curved in S-shape returns with its other end to its first-mentioned end.

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