EP1365919B1 - Method and device for printing on the surface of a strip-shaped medium - Google Patents

Abstract

A problem associated with label printers for liner-free labels is that the self-adhesive coated surface (4) of the label strip to be printed is exposed as it passes through the printer and is guided over a roller (10) that transports the label strip through the printer. Said strip must be released from the roller to be issued at the exit (15) of the printer. According to the invention, instead of the provision of conventional scraper elements downstream of the roller (10), the label strip is embossed, which counteracts the tendency of the label strip to become wound around the roller (10), thus enabling the label strip to be detached from the roller (10) in a reliable manner.

Description

The invention relates to a method for printing on a surface of a strip-like medium whose other surface is coated self-adhesive and which is transported in its longitudinal direction by a printing unit in which the medium with its surface to be printed on a printhead and with its self-adhesive coated surface is passed over a driven roller, and on a suitable device for carrying out the method.

Such methods and devices are used in particular for the production of printed labels, which are glued in sales shops on goods. In particular, weight data, for example from a self-service scale, price information and / or bar codes are printed on the surface to be printed, which are important for the settlement of the sales transactions. The fact that the self-adhesive coated surface is passed through the printing process, brings over other conventional methods in which the self-adhesive coated surface is provided with a masking tape from which the finished printed labels are withdrawn for use, the advantage that the printing process usually in roll form supplied medium requires less space and at the same time the costs associated with the masking tape costs are saved. However, handling the media exposed with its self-adhesive coated surface during the printing process requires special measures to prevent the medium from sticking during printing.

In known methods and devices of the aforementioned type (EP 0 758 979 B1 and EP 0 758 955 B1), this problem is met by the fact that the roller and also other surfaces which come into contact with the self-adhesive coated surface during printing, with a adhesive-repellent coating are provided. However, this is not enough to safely detach the medium from the roller. Therefore, in these known methods and devices as a particularly important element in the transport direction behind the roller and the latter immediately adjacent a detaching blade or a small-caliber detaching roller arranged, the surface is coated adhesive repellent and passes over the strip-shaped medium and is thereby deflected by the roller.

The invention has for its object to provide a method and an apparatus of the type mentioned above, which are characterized by particular simplicity and reliability.

With regard to the method, this object is achieved in that the medium is imprinted a shape behavior by which it separates from the roller.

The strip-shaped medium, which is usually a thermal print paper, tends to run after the roll with which it is engaged for its transport on its self-adhesive coated surface, ie to wind around the roll, if not In the transport direction behind the roller arrangements are made to detach the medium from the roller. In the solution according to the invention, such precautions are dispensed with. Instead, the shape characteristic imprinted on the medium ensures that it separates from the roller as soon as it is no longer guided into engagement with the roller. In most cases, this guide is made by the print head, which is usually tangential to the roller and in opposition to this is arranged and exerts on the surface to be printed of the medium acting in the direction of the roller pressure. As the media is transported between the printhead and the platen, this guide is released, allowing the media to develop its embossed formability, forcing it into a shape that deflects it away from the platen.

A first basic embodiment is that the medium is impressed in its longitudinal direction, a curvature, the center of curvature of which is opposite to the surface to be printed during its transport in front of the roller.

This embodiment is based on the fact that the strip-shaped medium, because of its inherent rigidity, endeavors to maintain the embossed curvature. Even if it is straight stretched after the curvature impression in its transport to the roller, it takes after the passage through the roller to its curvature again. This means that it bulges away from the roller and thereby safely detached.

An expedient further embodiment of this basic embodiment is that the medium is transported on its surface to be printed with a suitable angle for embossing angle over a suitable radius having embossing cylinder. While the medium is running around the embossing cylinder, the desired curvature is continuously impressed. By dimensioning the wrap angle and the radius of the embossing cylinder, the desired amount of curvature can be adjusted.

A second basic embodiment of the invention consists in embossing the medium with a rib running in its longitudinal direction before leaving the driven roller.

By this rib receives the strip-shaped medium increased longitudinal stiffness and an increased tendency to straighten. Therefore, as it passes over the roller, the strip-like medium detaches approximately tangentially from the latter, preventing it from wrapping around the roller.

Appropriately, this basic embodiment is carried out such that the rib is impressed on the two parallel to the longitudinal edges of the medium. The embossed on both edges of the medium ribs not only its tendency to straighten the direction is particularly strengthened, but at the same time the entire between the space available for printing on the edges of the medium, so that the profiling of the medium caused by the ribs does not disturb the printed image generated in the free space.

In this embodiment of the method according to the invention, it is also allowed that the medium before its passage through the printing unit in its longitudinal direction, a curvature is impressed, the center of curvature of the self-adhesive coated surface is opposite. This curvature is usually caused by feeding the strip-shaped medium from a roll in which it is wound so that the self-adhesive coated surface faces the center of the roll. The strip-shaped medium is therefore initially curved on entry into the roller in such a way that it tends to wind up on the roller. Due to the embossing of the rib, however, it is aligned against this curvature straight and therefore reliably detached from the roller.

The basic principle of a device according to the invention suitable for carrying out the method according to the invention is specified in claim 7. In order to carry out the method variants dealt with under the first basic embodiment, suitable embodiments of the device are specified in claims 8 to 15, and devices which are suitable for carrying out the method variants discussed under the second basic embodiment in claims 16 to 19. The device features of Claims 20 to 22 are expediently applicable in all cases.

Fig. 1

eine schematische Darstellung einer ersten Ausführungsform einer Vorrichtung zum.Drucken, und

Fig. 2 (a) und (b)

Ansichten der Anordnung einer Walze und eines Druckkopfes bei einer zweiten Ausführungsform einer Vorrichtung zum Drucken.

Further features, details and advantages of the invention will become apparent from the following description and the drawing, wherein the invention is explained and illustrated by means of embodiments. Herein show:

Fig. 1

a schematic representation of a first embodiment of a device for printing, and

Fig. 2 (a) and (b)

Views of the arrangement of a roller and a print head in a second embodiment of an apparatus for printing.

The embodiment shown in Fig. 1 comprises a base plate 1, on which all components of the device are mounted. A to be printed, strip-shaped medium is wound in the form of a supply roll 2, which rotatably supported on the base plate 1 is. The medium consists, for example, of thermal printing paper whose surface 3 to be printed on the other side 4 is self-adhesive coated. Such media are known in the art as "linerless label material" or "linerless label web". The supply roll 2 is wound in such a way that the self-adhesive coated surface 4 faces the center of the supply roll 2.

At a distance from the supply roll 2, a guide roller 5 is rotatably mounted coaxially with this on the base plate 1. Coaxially to the guide roller 5 and set back relative to this in the direction of the supply roll 2, a stamping cylinder 7 is fixedly or rotatably supported on a carrier 6 connected to the base plate 1. At a side facing away from the embossing cylinder 7 end portion of the support 6, a strip-shaped thermal print head is arranged, which extends in a direction perpendicular to the base plate 1, ie parallel to the axes of the guide roller 5 and the embossing cylinder 7 level.

The print head 8 extends tangentially to the casing 9 of a roller 10, which is rotatably mounted in opposition to the print head 8 on a support plate 11 connected to the base plate 1. The roller 10 is driven via a schematically indicated gear transmission 12 by a likewise only schematically indicated electric motor 13, which is arranged on the base plate 1. Further, a guide roller 14 is rotatably mounted on the bearing plate 11 at a location between the roller 10 and the embossing cylinder 7 position.

The supplied from the supply roll 2 strip-shaped medium extends from the supply roll 2 to the guide roller 5, over which it passes with its self-adhesive coated surface 4, and on to the embossing cylinder 7, over which it is carried away with its surface to be printed 3. From the embossing cylinder 7, the medium extends to the guide roller 14, over which it passes with its self-adhesive coated surface 4, and further to the roller 10, on which it with the self-adhesive coated surface 4 by the voltage applied to the surface to be printed 3 8 printhead is held. By this engagement, the introduced through his electric motor 13 and the gear transmission 12 in the roller 10 rotational movement is transmitted to the medium, whereby it is subtracted from the supply roll 2 and transported in its longitudinal direction. The transport movement and the operation of the thermal print head 8 (not shown) in such a manner coordinated by an electronic control that by the print head 8 on the surface to be printed 3 of the medium during its passage between the print head 8 and the roller 10 desired content be printed. In particular, it will be used for product labeling Printed labels that are torn from the strip-shaped medium after its passage through the device. In order to assist in the tearing off, a tearing strip 16 pointing to the printing surface 13 is provided at the outlet 15 of the device, which extends over the width of the strip-shaped medium, as a result of which the printed labels can be torn off.

The mutual relative position of the two deflection rollers 5, 14 and the embossing cylinder 7 determine the wrap 17, with which the medium is guided around the embossing cylinder 7. The radius of the embossing cylinder 7 is relatively small, whereby the medium undergoes a stretching on its surface 3 to be printed with respect to its self-adhesive coated surface 4. As a result, a permanent curvature is impressed on the medium in its longitudinal direction, whose center of curvature is opposite to the surface 3 to be printed. Although the medium is against this curvature by that of the roller 10 in the longitudinal direction of the medium, d. H. its transport direction, train exerted straight during its transport between the embossing cylinder 7 and the guide roller 14 and between the guide roller 14 and the roller 10 again, but takes the after its passage between the roller 10 and the thermal print head 8 released from the Transportzug medium embossed Curvature, as shown at 18, again. As a result, the medium is reliably detached from the roller 10, since the force with which the embossed curvature is assumed sufficient to overcome the adhesive force between the shell 9 of the roller 10 and the self-adhesive coated surface 4 of the medium.

Notwithstanding the shown in Fig. 1 spaced arrangement of the guide roller 5 and the embossing cylinder 7, the guide roller 5 could be arranged such that it forms in its operating position with the embossing cylinder 7 a roll clamping gap through which the medium passes. In this case, two axial generatrices of the deflection roller 5 and the embossing cylinder 7 facing each other on both sides of the medium and determine the point at which the wrap 17 begins. So that the medium can be inserted without difficulty when replacing the roller 2, an adjusting device (not shown) is provided, with which the guide roller and the embossing cylinder can be moved relative to each other in a release position in which they are mutually spaced and the insertion of the strip-shaped Enable mediums.

In this embodiment, therefore, the mutually facing generatrices of the embossing cylinder 7 and the upstream in the transport direction arranged deflection roller determine the beginning of the wrap angle. Additionally or alternatively could such a deflection roller also be arranged downstream of the embossing cylinder 7 (not shown) in order to determine the end of the wrap angle 17 in the same way.

In the transport direction immediately behind the print head 8 and the roller 10, the surface 3 to be printed faces a guide element 19, which is supported on the carrier 6. This guide element 19 extends to the output of the device and limits the peeling angle 20 caused by the impressed curvature, which the medium occupies with respect to the casing 9 of the roller 10 as a result of the impressed curvature. In this way, the medium is safely led out of the device after it has been torn off at the tear strip 16.

The lateral surfaces of the deflection rollers 5 and 14 and the roller 10, over which the medium with its self-adhesive coated surface 4 passes, are designed adhesive-repellent, for example by suitable coatings.

The arrangement of the transport of the medium serving roller 10 in relation to the print head 8 corresponds to the known prior art in the field of label printers. Therefore, the roller 10 is often referred to as a "pressure roller". However, it is also conceivable to arrange the transport roller 10 in the transport direction behind the print head 8 and to provide a non-driven counter element for the print head 8 which holds the medium in contact with the print head 8 for the printing operation.

If the medium by its wrap of the embossing cylinder 7 still should not take sufficient curvature, a cascade of several embossing cylinders 7 may be provided, which are circulated in succession by the medium during its transport.

Another embodiment, of which only parts are shown in FIG. 2, is consistent with the embodiment shown in FIG. 1 with respect to the arrangement of the supply roll 2 on the base plate 1, the comparison of the thermal print head 8 and the roller 10 and their drive through the Electric motor 13 via the gear transmission 12 coincide. Notwithstanding the embodiment shown in FIG. 1, however, no curvature embossing is provided in the embodiment of FIG. 2 on the transport path between the supply roll 2 and the roll 10, and no element corresponding to the embossing cylinder 7 is present.

The withdrawn from the supply roll 2 medium, however, due to this roll-shaped winding a certain pre-curvature, the center of curvature of the self-adhesive coated surface 4 is opposite. This pre-curvature is shown symbolically in FIG. 2 (a), which shows a schematic axial plan view of the roller 10 and the print head 8, although the medium in the transport direction in front of the roller 10 is actually stretched straight in line with the tension applied by the roller 10 ,

From Fig. 2 (a) and in particular the axial section through the roller shown in Fig. 2 (b) can be seen that in the shell 9, two circumferential, radially outwardly open grooves 21, 21 'are formed of semicircular cross-section. These grooves 21, 21 'are arranged near the two axial ends 22, 22' of the shell 9 arranged on a roller core 23. At the tangential to the casing 9 extending strip-shaped print head 8 two lugs 24, 24 'are formed, which engage in the grooves 21, 21' and have a cross-sectional shape complementary to the cross-sectional shape thereof. In the medium, the lateral edges 25, 25 'with the axial ends 22, 22' are approximately flush, are in its transport between the roller 10 and the print head 8 by acting on its surface to be printed 3 noses 24, 24 'in the longitudinal direction extending ribs 26, 26 'impressed. Through these ribs 26, 26 ', the medium in the transport direction behind the print head 8 and the roller 10 is straightened. As a result, it is reliably detached from the roller 10, against the initial tendency by the original pre-curvature to wrap around the roller 10.

The straightened medium reaches the exit of the device, where a tearing strip 16 of Fig. 1 is arranged corresponding element in order to tear off individual labels.

Since the two grooves 21, 21 'are disposed near the axial ends 22, 22', there is a printing area utilizing almost the entire width of the medium therebetween, which is shown by a double arrow 27 in Fig. 2 (b), for printing ,

As in the embodiment of Fig. 1, the jacket 9 of the roller 10 is formed adhesive repellent, as well as any guide elements, not shown, for the medium on its transport path between the supply roll 2 and the roller 10, as far as these guide elements with the self-adhesive coated surface 4 in contact reach.

In the foregoing description, it has been assumed by way of example that in roll 2 the self-adhesive coated surface 4 of the medium faces the roll center. In this case, as shown in Fig. 1, the roller 2 rotates during unwinding of the medium in the counterclockwise direction. Alternatively, however, the roll 2 may be wound in such a way that the surface 3 to be printed faces the center of the roll. In this case, the roller 2 is inserted into the device so that it rotates during unwinding clockwise. By this type of winding the medium is already impressed on the roller 2 a pre-curvature, which is opposite to the curvature of the roller 10. With a suitable material, this shape behavior can already be sufficient to separate the medium from the roller 10, without requiring further impressing. In this case, the embossing cylinder 7 and the guide roller 5 having embossing device in Fig. 1 can be completely eliminated and the medium are transported directly from the roller 2 between the roller 10 and the print head 8.

List of reference numbers

1

baseplate

2

supply roll

3

to be printed surface

4

self-adhesive coated surface

5

idler pulley

6

carrier

7

embossing cylinders

8th

printhead

9

coat

10

roller

11

bearing plate

12

gear transmission

13

electric motor

14

idler pulley

15

output

16

floating toolbar

17

Wrap angle

18

impressed curvature

19

vane

20

peel

21, 21 '

groove

22, 22 '

axial ends

23

roll core

24, 24 '

nose

25, 25 '

lateral edges

26, 26 '

ribs

27

double arrow

Claims (22)

1. Process for printing on a surface (3) of a strip-form medium, the other surface (4) of which is self-adhesively coated, the said strip-form medium being conveyed in its longitudinal direction through a printing mechanism in which the medium, with its surface (3) to be printed, is directed to a print head (8) and is led, with its self-adhesively coated surface (4), over a driven roller (10), characterized in that a deformation, by means of which the medium is separated from the roller, is imprinted in the medium.
2. Process in accordance with claim 1, characterized in that a curvature is imprinted in the longitudinal direction of the medium while the said medium is being conveyed before the roller (10), the centre of curvature of the said medium lying opposite the surface (3) to be printed on.
3. Process in accordance with claim 2, characterized in that the medium, on its surface (3) that is to be printed on, is conveyed, with a looping angle (17) that is appropriate for imprinting, over an imprinting cylinder (7) that has a radius that is suited to this.
4. Process in accordance with claim 1, characterized in that a flute (26, 26') is imprinted longitudinally into the medium, before the said medium leaves the driven roller (10).
5. Process in accordance with claim 4, characterized in that the flute (26, 26') is imprinted in the two rims (25, 25') of the medium running parallel to the longitudinal direction.
6. Process in accordance with claims 4 or 5, characterized in that, before passing through the printing mechanism, the medium has a curvature imprinted into it, the centre of curvature lying opposite the self-adhesively coated surface (4).
7. Device for printing on a surface (3) of a strip-form medium, the other surface (4) of which is self-adhesively coated, with a printing mechanism that has a driven roller (10) by means of which the medium can, with its self-adhesively coated surface (4), be directed, in being conveyed, in its longitudinal direction, and has a print head (8) past which the medium is conveyed with its surface (3) to be printed on, characterized in that there is a device, through which the medium can pass, for imprinting a deformation, into the medium, that separates the said medium from the roller (10).
8. Device in accordance with claim 7, characterized in that the device serving to imprint the deformation is formed by a stamping press (5, 7), disposed before the roller (10) as seen in the direction of conveying, for imprinting a curvature running in the longitudinal direction of the medium, the centre of the curvature concerned lying opposite the surface (3) to be printed on.
9. Device in accordance with claim 8, characterized in that the stamping press has an imprinting cylinder (7), with a radius suited to imprinting the curvature, around which the medium can be guided on its surface (3) that is to be printed on and with a relevant looping angle (17).
10. Device in accordance with claim 9, characterized in that the imprinting cylinder (7) is stationary.
11. Device in accordance with claim 7, characterized in that the imprinting cylinder (7) is disposed such that it can rotate around the axis of the cylinder.
12. Device in accordance with one of claims 9 to 11, characterized in that there is a guide pulley (5), serving to set the looping angle (17), over which the medium can be conveyed on its self-adhesively coated surface (4).
13. Device in accordance with claim 12, characterized in that the guide pulley (5) is disposed at a separation from the imprinting cylinder (7).
14. Device in accordance with claim 12, characterized in that the guide pulley can be shifted between an operating position, in which, with the imprinting cylinder (7), it forms a rolling wedging gap for the passage of the medium, and a release position in which it is separated from the imprinting cylinder (7).
15. Device in accordance with claim 14, characterized in that there are, in each case, two guide pulleys between the operating position and the release position, one guide pulley of which determines the start of the looping angle (17) and the other of which determines the end of the looping angle (17).
16. Device in accordance with claim 7, characterized in that the device serving to imprint the deformation is formed by the roller (10) and a counter element (24, 24'), which functions in conjunction with the roller (10) to imprint a flute (26, 26') extending in the lengthwise direction, is formed in the medium that can be conveyed between the roller (10) and the counter element (24,24').
17. Device in accordance with claim 16, characterized in that the counter element (24, 24') is disposed on the print head (8).
18. Device in accordance with claim 16 or 17, characterized in that the roller (10) has a surrounding groove (21, 21'), in the area of its roller shell (9), intended for guiding the medium, and in that the counter element has a lip (24, 24') projecting into the groove (21,21').
19. Device in accordance with claim 18, characterized in that the strip-form medium is a component part of the device and the groove (21, 21') and the lip (24, 24') are disposed on either side close to the two rims (25, 25') of the medium running parallel in the longitudinal direction.
20. Device in accordance with one of claims 7 to 19, characterized in that the medium to be fed in can be wound into a roll (2) in which the self-adhesively coated surface (4) faces the central point of the roller.
21. Device in accordance with claims 7 to 16, characterized that the medium to be fed in can be wound into a roll (2) in which the surface (3) to be printed on faces the central point of the roller.
22. Device in accordance with claims 7 to 21, characterized in that the surface areas of the device coming into contact with the self-adhesively coated surface (4) have anti-adhesive coatings.

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