DE4205945C2 - Ribbon guide in front of a printhead of a printer - Google Patents

Description

It is known a device for holding a exchangeable printhead, which is also used for mounting and guiding a replaceable ribbon in front of a pressure element guide housing, in front of the printhead face using webs and by means of arranged on both sides of the pressure element guide housing, with their Axes of rollers running perpendicular to the direction of print head movement form, with the ribbon in front of the print head and behind the Rolling around (DE 32 14 633 A1).

In the known device it is assumed that the ribbon cassette is open the print head carriage is attached, via webs with Upper edges and over sloping webs, the ribbon initially loosely put on the top edge. Once the ribbon is moved by the Carrier is transported, it slips off the sloping top edges and threads between the leading edges of the webs as well as those mentioned Pens automatically.  

That with ribbon cartridges and so-called ribbon cartridge, which is stationary on the printer upper part are attached, existing problem of threading the ribbon when Exchange of a used ribbon cassette for a new one Ribbon cassette, just consists of threading the ribbon between the face of the print head and those with their axes perpendicular to the direction of the print head movement. It is because of that already guides made of thin metal sheets and aids such. B. Plastic sliders have been suggested to be without touching the Get along ribbon and thread the ribbon.

There is a bow-shaped ribbon guide known (JP 3-121 880 A) around a Axis parallel to the print head movement direction from a ribbon-guiding position is pivotable into a ribbon-releasing position, with rollers on legs are rotatably mounted and the ribbon guide in the ribbon-guiding position on Printhead carriage is lockable. However, the known design obviously shows no printhead of a printer that can be pivoted away from the platen. The rolls there are not mounted on a pivotable bracket. These roles Rather, they belong to a separate ribbon guide, which serves the ribbon between the roller and the bracket.

Another known proposal (JP 1-171 897 A) provides a pluggable shield. The accessibility of the ribbon is not better here either because it is disadvantageous to have to remove the pluggable shield and thus with the ribbon in To come into contact. This ribbon guide is a mask with a spring, one end of which is arranged on the pivot axis of the ribbon guide and the other end of which faces another part of the print head carriage supports. The strength of this spring therefore decides whether the mask instead of one Wire bracket exerts a desired pressure on the ribbon without the ribbon to prevent it from running. As is known, the spring force changes over time the adjustment of the pressing force is already a problem.

It is still a self-adjusting role regulation of the traction in the Ribbon known (IBM, Technical Disclosure Bulletin Vol. 24 No. 7A, Dezenber 1981), on the basis of which the tension in the ribbon can be adjusted. A such a roll literally increases the effort required to ribbon change, and nothing else is gained in the area of the print head.

The invention specified in claim 1 is therefore the problem on the basis of a ribbon guide in front of a printhead, which with printhead carriage from the platen a pressure can be moved away, without the difficult threading of the ribbon.

The with the invention according to the characterizing part of claim 1 The advantages achieved are in particular that now the ribbon cartridge or ribbon cartridge, which on her Housing is equipped with pairs of pins or the like. Simply in the Printer or a hinged housing part of the printer used can be, without further handling the ribbon in front of the Printhead face, d. H. before the pressure elements come to rest. Then it is only necessary to fold up and close the wire bracket lock, the locking being a partial movement of the folding up can. The ribbon guide already holds the ribbon in the desired position. Other advantages are that Fold down the wire bracket to access the ribbon or Printer is increased significantly.  

It is also advantageous that the wire bracket in the the ribbon leading position on the print head carriage can be snapped into place. In the case of pivotable housing parts of a printer, the position of the Wire bracket fixed and prevents the wire bracket in the Open position is in which a closing of the device part hampers could be. However, the latching can advantageously also be straight can be brought about by closing the device part.

According to an improvement of the invention it is provided that on a projecting pivot axis of the wire bracket supported one end of a torsion spring the other end of the printhead carriage is supported. The force of the torsion spring closes the wire bracket with the rollers without any more here Handling steps would be required.

According to another embodiment, it is provided that the wire bracket made of magnetic material has at least one free end that in the leading the ribbon Position of the wire bracket against a permanent magnet attached to the print head carriage is present. The permanent magnet replaces other locking means and holds otherwise the wire bracket is always closed.

Another embodiment, however, provides that on one formed by the pivot axis and an angular portion of the Wire bracket and on the print head carriage a rubber element to swing the wire bracket up against the Printhead face attached is. Because the elastic element increased by opening the wire bracket under If the voltage is applied, the wire bracket closes again immediately in the position leading the ribbon as soon as the wire bracket from the User of the printer is released.  

Finally, an improvement of the invention is that the Rollers on resilient legs of the wire bracket are rotatably mounted and that the ends of spring legs of the wire bracket each on the print head carriage are articulated. Here, too, occurs due to the spring action Wire bracket automatically into its desired closed position.

An embodiment is shown in the drawing and is described in more detail below. It shows

Fig. 1 is a plan view of a print head carriage with print head, and a wire hanger for the ink ribbon,

Fig. 2 seen the print head carriage without print head from the side with the wire bracket closed and

Fig. 3 shows the print head carriage without a print head, but with the wire bracket open.

A print head 1 with its print elements (not shown) located on a print head face 1 a has a print element guide housing 2 for guiding the print elements consisting of print needles. In addition to the pressure element guide housing 2 , rotatably mounted rollers 3 are arranged on roller axes 4 . The rollers 3 run with their roller axes 4 perpendicular to a print head movement direction 5 , in which the print head 1 can be moved back and forth and which corresponds to the direction of a print line to be written.

An ink ribbon 6 is guided in front of the print head face 1 a and behind the rollers 3 . For this purpose, the rollers 3 are rotatably mounted on a wire bracket 7 , namely each roller 3 on a leg 7 a or 7 b of the wire bracket 7 . The wire bracket 7 has at the ends of the legs 7 a and 7 b angularly bent pivot axes 8 , which lie on a common axis 8 a and are inserted into corresponding bores 8 b. The holes 8 b are located on corresponding projections of a print head carriage 9 , the z. B. is injection molded from plastic. About the axis 8 a bracket 7, the wire of a ribbon 6 leading position 10 (Fig. 2) can be pivoted into a ribbon 6 releasing position 10 a (Fig. 3).

The wire bracket 7 can also be snapped into position 10 ( FIG. 2) on the print head carriage 9 between slightly flexible or even resilient locking recesses 10 b, consisting of slots open on one side ( FIG. 3). The carriage 9 is in parallel slide guides 9 a and b stored. 9

The folding up of the wire bracket 7 to the position shown in Fig. 2, the ink ribbon 6 leading position 10 is caused by a torsion spring 11 which is disposed on a protruding pivot axis 8 at a free end 12 and with one end 11 a on the print head carriage 9, and with the other end 11 b is supported on the pivot axis 8 .

Another automatic swiveling up of the wire bow 7 consists in pulling it against a permanent magnet attached to the print head carriage 9 and thus fixing it.

On a part of the wire bracket 7 formed by the extended pivot axis 8 , namely the free end 12 of the wire bracket 7 and an angular cut, and on the print head carriage 9 , a rubber pulling element 13 is also arranged. The pivoting up of the wire bracket 7 is also set up automatically in such a way that the rollers 3 on resilient legs 7 a, 7 b of the wire bracket 7 are rotatably mounted and that the ends 14 of the spring legs 14 a are each articulated on the print head carriage 9 .

Reference list

1 printhead
1 a printhead face
2 pressure element guide housing
3 rolls
4 roller axes
5 Printhead movement direction
6 ribbon
7 wire clips
7a leg of the wire bracket
7 b leg of the wire bracket
8 swivel axes
8 a common axis
9 print head slides
9 a slide guide
9 b carriage guide
10 ribbon leading position
10 b notches
10 a Ribbon-releasing position
11 torsion spring
11 a end of the torsion spring
11 b end of the torsion spring
12 free end of the wire bracket
13 elastic element
14 a spring leg
14 ends of the spring legs

Claims (5)

1. ribbon guide in front of a print head on a print head carriage of a printer, with rollers arranged on both sides of the print element guide housing, with their axes running perpendicular to the direction of movement of the print head, with an ink ribbon that is guided around in front of the print head end face and behind the rollers, characterized in that the rollers ( 3 ) on legs ( 7 a, 7 b) of a wire bracket ( 7 ) are rotatably mounted that the wire bracket ( 7 ) about pivot axes ( 8 ) in the print head carriage ( 9 ) is pivotable, the pivot axes ( 8 ) on a common, in Printhead movement direction ( 5 ) extending axis ( 8 a) are arranged so that the wire bracket ( 7 ) with the rollers ( 3 ) from a position ( 10 ) leading the ribbon ( 6 ) into a ribbon ( 6 ) of the rollers ( 3 ) releasing position (10 a) of the printhead front face (1 a) can be pivoted away, and in that the wire bracket (7) in which the ink ribbon (6) leading position (10) on the printhead carriage ( 9 ) can be snapped into place. 2. Ribbon guide according to claim 1, characterized in that on an overhanging pivot axis ( 8 ) of the wire bracket ( 7 ) one end ( 11 b) of a torsion spring ( 11 ) is supported, which with the other end ( 11 a) on the print head carriage ( 9 ) is supported. 3. Ribbon guide according to one of claims 1 and 2, characterized in that the wire bracket ( 7 ) consisting of magnetic material has at least one free end ( 12 ) which in the ribbon ( 6 ) leading position ( 10 ) of the wire bracket ( 7 ) against a permanent magnet attached to the print head carriage ( 9 ). 4. Ribbon guide according to one of claims 1 and 2, characterized in that on a part formed by the pivot axis ( 8 ) and an angular section of the wire bracket ( 7 ) and on the print head carriage ( 9 ) has a rubber pulling element ( 13 ) for pivoting the wire bracket ( 7 ) is fixed against the printhead face ( 1 a). 5. Ribbon guide according to one of claims 1, 2 and 4, characterized in that the rollers ( 3 ) on resilient legs ( 7 a, 7 b) of the wire bracket ( 7 ) are rotatably mounted and that the ends ( 14 ) of spring legs ( 14 a) of the wire bracket ( 7 ) are each articulated on the print head carriage ( 9 ).