UNBALANCED ROLLER

Abstract

An imprinting, texturing or embossing system for a roll-to-plate process including at least one roller and at least one device capable to exert a resetting force to the starting position of the imprinting process after imprinting wherein the roller is a freely rotating roller.

Claims

1. An imprinting, texturing or embossing system for a roll-to-plate process comprising at least one roller and at least one means capable to exert a resetting force to the starting position of the imprinting process after imprinting, wherein the roller is a freely rotating roller.

2. The system of claim 1 wherein the means to exert a resetting force are comprised in the at least one roller.

3. The system of claim 1 wherein the means to exert a resetting force are connected to the at least one roller.

4. The system according to claim 1 wherein the roller has at least one mounting point for the means.

5. The system according to claim 4 wherein the mounting points being one or more holes, gears or magnets.

6. The system according to claim 4 wherein the means are mountable over the whole circumference of the roller.

7. The system according to claim 4 wherein the means being mountable on a circular ring, slot or disc fixed to the roller.

8. The system according to claim 1 wherein the means are one or more items which exert the resetting force by their mass.

9. The system according to claim 8 wherein the items which exert the resetting force by their mass having an additional mass of not more than 5% of the mass of the roller.

10. The system according to claim 8 wherein the items which exert the resetting force by their mass are mounted not surpassing the roller's diameter.

11. The system according to claim 8 wherein the items which exert the resetting force by their mass are mounted in the inner area of the roller.

12. The system according to claim 1 wherein the means is a spring.

13. The system according to claim 12 wherein the means is a spiral, leaf or rotational spring.

14. The system according to claim 1 wherein the means is a magnet or an electromagnet.

15. The system according to claim 1 wherein two or more means exert the same or different resetting forces and wherein said means are mounted at different positions of the roller.

16. The system according to claim 1 wherein the means is a motor.

17. The system according to claim 1 wherein the circumference of the roller is larger than the length of the substrate and/or larger than the length of the carrier.

Description

[0014] In a preferred embodiment, the means for exerting the resetting force are mounted on one or more mounting points off the roller's rotation axis in order to transform the resetting force into a torque which is strong enough to reset the roller into the predefined position. Advantageously, the means are mounted in a way that they can easily be removed without leaving any remainders at the roller and without putting any damage to the roller. Depending on the embodiment, the means may be fixed using force-fit, form-fit or other fixation techniques. The radial deviation of the one or more mounting points from the rotation axis of the roller depends on the moment of inertia and the diameter of the roller as well as on the strength of the resetting force. In a more preferred embodiment, the one or more mounting points are located at one or both face sides of the roller, inside a hollow roller and/or on the circumferential shell of the roller close to the face sides of the roller to obtain a maximum torque at a defined strength of the resetting force. Placement of the means inside the roller is especially advantageous as in such case they have least potential of disturbing the imprinting process. By the preferred position of the means, the resetting force can be exerted to the roller without hindering use of other building elements of the imprinting apparatus.

[0015] In a more preferred embodiment, the one or more mounting points are holes, preferably threaded holes, bolts, preferably threaded bolts, rods or spikes, straight or curved slots, rails, clamps, hooks, loops, anchors or magnets which are either incorporated into the material of the roller or installed on the outside of the roller using holes, bolts, rods or spikes, slots or using magnetic forces. An advantage of this embodiment is that the means can be fixed in various positions on the roller and to also use more than one means in order to vary the strength of the resetting force. Additionally, existing rollers can be upgraded with the means as applied in the invention.

[0016] The one or more mounting points can receive complementary fixation elements of the means such as threaded or unthreaded bolts, rods or spikes, screws, anchors, threaded or unthreaded holes, rails, straight or curved slots, clamps, hooks, anchors or magnets. In a further embodiment, the means are adhered to the roller using any kind of glue such as solvent-based glue, hot-melt glue or two-component glue offering a large amount of flexibility in the choice of the mounting point. Preferably the glue is chosen such that it can be removed without remains from the roller and without damage of the material of the roller. Use of glue for the fixation of the means offers a large amount of flexibility in the choice of the fixation point and furthermore facilitates upgrading of existing facilities lacking any other mounting points in an advantageous manner.

[0017] More preferably, the mounting point is a concentric circle in reasonable radius around the rotational axis of the roller forming e.g. a circular rail, a circular slot or a magnetic unit such as a magnetic ring or disc to receive the means using fixation elements such as clamps, bolts, loops, hooks, anchors or magnets which allows to fix the means in an arbitrary angular position and therefore choose a preferred position with great precision as the predefined position and to also change the predefined position as simply as possible if necessary, e.g. in case the roller has received damage which has to be circumvented in the imprinting process.

[0018] In an embodiment of the invention, the means to exert the resetting force can be springs such as spiral springs, leaf springs or rotational springs.

[0019] In another embodiment, the means to exert the resetting force may be magnets or electromagnets. This embodiment of the invention is especially advantageous as magnets can very easily be installed also to an existing roller either by just attaching them to a magnetic roller in the sought-after position or by using e.g. a magnetic disc or foil attached to the roller using e.g. glue. The use of electromagnets offers the additional advantage that the resetting force can also be switched off if needed.

[0020] In another embodiment the means to exert the resetting force is a motor, which steers the freely rotating roller to the preferred position after the imprint process. The motor can drive the imprint roller by use of a gear, belt or roller. As example a second roller, being in contact with the imprint roller after the imprint cycle, can rotate the imprint roller to a predefined position. In this case the imprint roller will need means to determine the position of the roller.

[0021] In the preferred embodiment, just one means exerts the resetting force to the roller. In a further embodiment, two or more means which may for themselves exert different resetting forces are mounted to different positions of the roller in order to make sure that the roller cannot be caught in a metastable position.

[0022] In a preferred embodiment the means to exert the resetting force are one or more items which are attached to the roller and which exert the resetting force by their mass and reset the roller to a predefined position due to the attractive force caused by gravity. In contrast to other means, items with additional mass allow for a proper resetting to the predefined position also in cases where the roller has conducted a full rotation since they are not damaged by overbending as it may occur with springs. Furthermore, items with additional mass show most resistance against wear or damage when used as means to exert the resetting force

[0023] In a preferred embodiment of the invention, the mass added to the roller by mounting the items is not more than 5%, mostly preferred not more than 2% of the mass of the roller in order to make sure that the imbalance added to the roller by the items is large enough to exert the sought-after resetting force but small enough to make sure that the imbalance induced by the mass pieces has no or a negligible effect on the result of the imprinting and also does neither provide damage or additional wear to the roller nor to the flexible stamp, the substrate, the belts, the carrier or other devices involved in the imprinting process.

[0024] In a preferred embodiment, the additional items which exert the resetting force by their mass are shaped in a way that they do neither outstand the roller's diameter nor touch the flexible stamp or the driven belts and therefore do not disturb the imprinting process by friction or other kinds of mechanical interaction with the flexible stamp, the belts, the substrate or other devices involved in the imprinting process. This embodiment facilitates upgrading of existing facilities in an advantageous manner.

[0025] In a preferred embodiment the roller diameter is chosen to have a circumference which is larger than the length of the substrate to be imprinted in the direction of imprinting. If a carrier is used in the roll-to-plate imprint apparatus, the roller circumference is preferably larger than the length of the carrier in the imprint direction. Hereby defects on the roller can be positioned, by use of the imbalance outside of the imprint area.

[0026] In a preferred embodiment of the invention, items which exert the resetting force by their mass of different masses have the same dimension in order to allow for optimal fit with the dimension of the apparatus. This can be achieved by using different items of the same dimension made from materials of different density such as tin, steel, brass, copper or lead. Also non-metallic materials such as ceramics may be used. In a further embodiment, the items may be small, preferably rigid containers which can be filled with variable amounts of water, other liquids or bulk goods such as sand.

DESCRIPTION OF FIGURES

[0027] The figures show a preferred embodiment of the invention, however they do not limit the description of the invention to this embodiment in any sense and have just illustrative character. Indicating numbers occurring in more than one figure mean the same in all figures.

[0028] FIG. 1 shows schematically an imprinting apparatus to be used with an unbalanced roller according to the present invention. In this apparatus, a planar substrate 101 which is placed on a carrier 102 is moving on moving means 103 underneath a set of non-driven imprinting rollers 108. Imprinting is done by a textured foil 104 which is used as a flexible stamp with an active area 104A carrying the imprinting or embossing pattern. The flexible stamp is fastened to belts 106 using a first clamp 105A and a second clamp 105B. The belt is guided over driven pulleys 107 which rotate independently of the rollers 108. Therefore the rollers are only rotating passively following the movement of the textured foil 104. The flexible stamp is coated with an imprinting lacquer 109 being released from a nozzle 110 which is then carried onto the substrate 101 and cured using the UV lamp 111. Note that the lacquer 109 can also be directly applied on the substrate 101.

[0029] FIG. 2 shows a detailed view of a roller 108 in a preferred embodiment of the invention with mounting holes 201 on the facing side 203 to which an item which exerts the resetting force by its mass 202 is mounted.

[0030] FIG. 3 shows another embodiment of the roller 108 with a rotational axis 204 and a concentric circular rail 301 mounted on the roller's face side 203. A block-sized item which exerts the resetting force by its mass 303 is equipped with a clamp 304 which allows to fix it to the rail 301.

[0031] FIG. 4 shows another embodiment of the roller 108 from FIG. 2 with a rotational axis 204 and mounting holes 201 on the facing side 203 to which a metal rod 401 as item with additional mass is fixed inside the roller 108.

[0032] FIG. 5A shows the same embodiment of the roller as FIG. 2 with the roller 108 and the mass piece 202 where the roller is damaged by a scratch 501 which would result in a faulty imprint. The rotation direction of the roller during the imprinting process is indicated by the curved arrow.

[0033] FIG. 5B shows the imprinting process using the roller 108 with the scratch 501 and using the flexible stamp 104.

[0034] FIG. 5C shows the possible result of the imprint process 502, containing cured resin 109, using the damaged roller 108 with the image of the scratch 503 outside of the active area 104A. The vertical line 504 indicates the starting point, depending on the predefined position of the imprint process, due to the mass piece 202 while the arrow 505 indicates the direction of the imprinting process on the substrate 101. This process makes sure that the image of the scratch is always located at the same position on the imprint and may therefore be located in an area where it does not cause problems in the imprint.