CH647721A5 - Ribbon cartridge. - Google Patents

Description

647721

2nd

PATENT CLAIMS

1. Ribbon cassette with a device made of wire for tensioning and guiding the ribbon, characterized in that the wire (10) fastened to a cassette wall (2) has two sections (11, 12) which are arranged approximately at right angles to one another, with an angle -lung (14) at the intersection of the two sections (11, 12) resiliently engages in a toothed disc (20) of the supply spool (4) and the second section (12) of the wire (10) has an angled portion (15) at its free end Guide of the ribbon (16) carries.

2. Ribbon cassette according to claim 1, characterized in that the wire (10) with the. the first section (11) is arranged above and with the second section (12) below the supply reel (4) in the cassette (1).

3. Ribbon cassette according to claims 1 and 2, characterized in that the first section (11) of the wire (10 under prestress by means of the one bend (14)

engages in the toothed disc (20) of the supply reel (4) and is supported on a projection (18) of the cassette wall (2).

4. Ribbon cassette according to claims 1 to 3, characterized in that the ribbon (16) coming from the supply spool (4), and the bend (15) at the free end of the second section (12) of the wire (10) and from there a deflection (30) is laid around in the cassette (1), the deflection (30) lying to the side of the supply reel (4) on a level which corresponds to approximately half the radius (r) of the full supply reel (4).

The subject of the innovation is an ink ribbon cassette with a device made of wire for tensioning and guiding the ink ribbon. Ribbon cassettes are known in which the ribbon is wound onto a supply spool. From this, it is pulled off by means of a drive device, guided past the impression point and pulled back into the cassette. In some of these cartridges, the used ribbon is rewound on a spool. This spool can sit on a pivotable, spring-loaded lever, which swivels with increasing band diameter against the force of the spring in the direction of the supply spool. This arrangement has the advantage that the cassette can be kept smaller because the diameter of the supply reel decreases while the diameter of the take-up reel increases. The take-up reel can then reach into the area of the supply reel because it is movably mounted.

With such cassettes, however, it is absolutely necessary to brake the supply reel. This must be done because it must be avoided that the ink ribbon runs off the spool unintentionally and forms loops, or that the printing point is not under a certain tension. On the other hand, the running belt must run over certain guides, at least one of which serves as a belt tensioner.

A cassette has become known, from which a band tensioner formed from spring wire emerges, which at the same time, by means of a bend at its free end, engages radially in a toothing of a disk lying under the supply reel. However, this arrangement has several disadvantages. For one thing, it is inconvenient

that the ribbon runs with its layer side over the belt tensioner. As a result, ink particles are scraped off the ink ribbon, so that the ink ribbon does not get undamaged to the impression point. Bad prints are the result of this. This phenomenon cannot be avoided either

if a roller is attached to the belt tensioner to guide the belt.

In addition, the known cassette has the disadvantage that

that when the tape is transported, the tape tensioner emerges from the toothing of the toothed disk lying under the supply reel in the initial stage of its movement. As a result, the supply spool is rotated immediately, which means that considerable masses have to be moved, especially when the spool is full. This mass movement at least partially hinders the lifting of the ribbon at the point of imprint in its guide members.

The disadvantages described occur in particular in the case of plastic tapes which consist of a thin film and are coated on one side with dye. It is the task of the innovation to avoid the disadvantages described. An arrangement according to the characterizing part of claim 1 is suitable for this purpose. This arrangement makes it possible to guide the back of the ink ribbon over the respective guides, so that damage to the ink layer is avoided. On the other hand, the arrangement allows that when the tape is pulled onto the tape, the tape tensioner first executes a certain movement before the tape brake exits from the toothing of the disk of the supply reel. As a result, much more favorable acceleration ratios of the masses to be moved are achieved, which has a positive effect on the one hand on the transport and on the other hand on the lifting of the ink ribbon. The arrangement of the resilient wire according to claims 2 and 3 allows a simple design of the wire, as well as the cassette and a cheap accommodation of the coil. The features of claim 4 support the intended effect.

The innovation is described with reference to the drawings, which represent a schematic embodiment. It shows:

Figure 1 is an ink ribbon cassette with a full supply spool.

Fig. 2, the cassette with an almost full take-up spool and

Fig. 3 shows the reduced representation of the resilient wire.

With 1 the cassette is designated, which is shown without a cover part. The cassette has a wall 2 all around and has a holding mandrel 3 for the supply reel 4. The holding mandrel 3 is formed in one piece with the cassette 1. A pivotable lever 5, which is under the action of a tension spring 6, carries the take-up spool 7. This is driven by means of a wheel 8 which carries pointed mandrels 9 which penetrate into the winding of the take-up spool 7. The wheel 8 is driven from the outside in a known manner, e.g. by means of a motor, on the shaft of which there is a coupling which engages in the shaft of the wheel 8. However, this is not shown in the drawing.

A wire 10, the shape of which can be seen in FIG. 3, is fastened to section 2a of the cassette wall 2. The wire 10 consists essentially of the two sections 11 and 12. For insertion into the wall 2 of the cassette, it is provided with an angle 13. A further bend 14 is provided between the two sections 11, 12, so that the level of section 12 is lower than that of section 11. In a manner to be described, sections 11 and 12 act as a band brake or band tensioner.

At the free end of section 12 is another bend 15, which, however, is directed upwards again.

This bend 15 serves as a guide for the ribbon 16 and can be provided with a roller 17 to reduce the friction. The wire 10 is supported in the area s

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of the section 11 on a projection 18 of the cassette wall 2 and is thus under a certain bias.

As can be seen from FIGS. 1 and 2, the wire lies with its section 11 up to the bend 14 above and with its section 12 below the supply spool 4. The bend 14 engages in the toothing 19 of a disk 20, which together with the Supply spool 4 sits on the mandrel 3 and rotates together with the supply spool 4.

The ink ribbon 16 runs from the supply spool 4, around the bend 15 or the roller 17, to a further deflection 30 which is likewise fixedly arranged in the cassette. From there it is led to the cassette outlet 21, goes to the impression parts, which are approximately in the is provided with the arrow 22, but is not shown. The used tape is drawn back into the cassette 1 through the opening 23, around further deflections 24 and 25, until it is finally wound onto the take-up reel 7.

If, by means of the drive described above, the wheel 8 pulls in the direction of the arrow 26 onto the ink ribbon 16, the section 12 of the wire 10 is first loaded, i.e. section 12 deflects in the direction of arrow 27. In the process, the bend 14 initially remains in engagement with the toothing 19 of the disk 20. The supply reel 4 therefore does not rotate immediately when a tension on the belt 16 takes place. Only in the further course of the tape transport does the bend 14 deviate from the toothing 19 of the disk 20, whereby the braking of the supply reel 4 is released. The deflection 14 is avoided by the section IIa of the wire 10 moving in the direction of the arrow 28. The result of the two movements 27 and 28 is shown in FIG. 1 by the 5 arrow 29.

The movement sequence mentioned is achieved, in particular, in that first the section 12 of the wire 10 executes a swiveling movement approximately tangential to the supply spool 4 and then the first section 11 of the wire 10 also makes a movement tangential to the supply spool 4, which, however, leads to the of the second section 12 is approximately vertical. As a result, the pulling movement of the band 26 initially goes into the resilient section 12 of the wire 10 and only then into the likewise resilient section 11 of the wire 10. Only with the second movement sequence is the supply reel 4 released for rotation. The mass represented by the supply spool 4 is therefore only moved at a later point in time, as a result of which the elevation 20 of the ink ribbon 16 is no longer adversely affected by the height of the printing line.

The intended effect can be influenced by various factors. One of them relates to the spring force and the pretension of the wire 10. Another 25 factor is the position of the deflection 30. Experiments have shown that a particularly favorable effect is achieved if the deflection 30 lies on one level to the side of the supply spool 4, which corresponds to approximately half the radius r of the full supply spool 4.

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2 sheets of drawings