EP0965446B1 - Security printing machine for printing security paper - Google Patents

Abstract

The security mark printer has a preheater (13) for the print ribbon (8,8a) upstream of the applicator cylinder (5) to preheat the image (7) which are printed onto the paper web (1) by simple contact of the printer stamps (52) with the images against the press cylinder.

Description

The present invention relates to a printing machine security on securities, especially banknotes, comprising a device paper feed in the form of sheets, a paper transport device and unit application of security images supported by at minus a ribbon which is brought into contact with the paper as these images are applied to locations determined paper corresponding to the impressions of securities, the application unit comprising a applicator cylinder provided with pads arranged on the periphery of the applicator cylinder in register with said determined locations, cooperating with a pressure cylinder between which the paper runs, said ribbon being mounted between two reels of unwinding, respectively winding the ribbon, the ribbon running parallel to the paper path.

It is already known to create safe zones on securities and in particular on banknotes bank, by applying images in the form of film in order to make it difficult to falsify them, in particular their reproduction by the use of photocopiers with a reproduction quality of more and more perfected. These images are often optically variable images comprising either a kinegram, or a hologram which have the characteristic of changing appearance according to angle under which we look at them. Applying these images can be done either hot or cold. In EP-A-0625 466 by the same applicant, an installation is described allowing such cold images to be applied in using a two-component adhesive, the first component being applied at the location provided on the tickets partially or totally printed on a sheet and it is dried by the passage of the sheet in front of a catalyst. Subsequently by means of a applicator cylinder and a pressure cylinder, the images with the second component are applied on the locations previously provided by simple pressure.

In the aforementioned machine, the ribbon moves between two cassettes according to a generator of the cylinder applicator. The applicator cylinder is provided with several pairs of these cassettes to allow applying multiple images to a single pass several places on a leaf.

There is also another type of installation which includes an image application unit optically variable carried by a ribbon provided for each printing column and which is unrolled between a take-up reel and a take-up reel. The path between the two coils includes, in addition to tension guide rollers and rollers, a cylinder provided with circumferential grooves, interrupted by bridges, said ribbon passing through said grooves. The leaves to be treated pass by between said cylinder and pressure cylinders and the image transfer takes place every time a bridge passes on the pressure cylinder. The cylinder of the applicator is heated to allow activation of the adhesive carried by the image. So that the adhesive can be heated enough to achieve the effect desired, the contact between the cylinder bridge applicator and the images should last a while, which means that the dimensions of the cylinder applicator and those of the pressure rollers must always be adapted to the size of the leaves and partially printed securities or totally on said leaves. The ribbon including the images scroll continuously and synchronism with the leaves on which the images must be applied. This installation performed by the depositor gives satisfaction.

However, the obligation to maintain contact between the applicator cylinder and the image to be transferred during a period, ask each time we change paper format to fundamentally change the applicator cylinder and pressure cylinder. On the other hand, the pressure cylinder used for keep the sheets in contact with the cylinder applicator before image transfer overwrite the full length sheet at both ends of the sheet in the direction of the paper movement. In effect, so that the sheet remains in contact with the applicator cylinder, two rolls of dimensions reduced press the sheet against the cylinder applicator near the ends of the sheet before the sheet receives the images so that the applicator cylinder bridge in close contact with the ribbon and allow to bring to the temperature desired the adhesive of the images to be applied and by the the sheet passes over a pressure cylinder which has the same width as the sheet, which allows obtain the application of the images on paper.

Thus, the pressure exerted by the two rollers initially ensuring the plating of the sheet against the applicator cylinder leaves unwanted traces on leaf.

Finally, the document WO-A-9 637 368 describes a security printing machine provided with a preheating device for preheating the images which will be applied to a sheet or to a strip by an applicator cylinder heated under high pressure ( typically 350-1000 bar).

The object of the present invention is to provide a machine similar to that described above, but free from the aforementioned disadvantages.

The machine according to the present invention is characterized by the fact that it is provided with a tape preheating upstream of the applicator cylinder to preheat the images that will be applied against the sheet of paper by simple contact of said stamps with images against the pressure cylinder.

The advantage of this machine is that the preheating of the images to be applied on the sheet avoids the obligation to use rollers pressure pressing against the two longitudinal edges of the sheet to ensure good contact with the applicator cylinder and obtain the desired heating. On the other hand, the fact that all it takes is a simple contact between the pads of the applicator cylinder and the printing cylinder to obtain the transfer of ribbon images on paper so you don't have to modify the machine when the ticket formats or leaves are changing, but just moving them buffers both axially and peripherally to adapt to the new dimensions of the sheet and tickets to print, the ribbon with the images to apply being prepared with the spacings corresponding to the new dimensions.

According to an alternative embodiment, the machine is characterized by the fact that in order to save the ribbon, it is provided with means making it possible to make advance the ribbon in synchronism with the sheet passing between the applicator cylinder and the pressure, to brake the tape advance and to do it retreat a distance equal to about the length of a sheet when the sheet has left the cylinder applicator while waiting for the sheet to arrive next and register the ribbon with the next sheet.

Thus, by means of this device, we arrive at save the length of the ribbon which in others facilities continues to run even between late of a sheet and the arrival of the new, which are always offset by at least a few centimeters. These means take advantage of this space between the end of a sheet and the start of the next to brake advance the ribbon and roll it back and put it in register with the following sheet.

The means used to obtain these results are a pair of feed rollers arranged downstream of the cylinder applicator advancing the ribbon, a pair of reversing rollers arranged upstream of the preheating to brake and reverse the tape, a device for reading register marks previously printed on the ribbon and ordering the rollers previously mentioned, as well as devices to assist the rollers during sudden changes gear changes arranged upstream of the rollers reversing, respectively downstream of the feed rollers.

Said devices for assisting the rollers are advantageously two negative pressure boxes in which the tape is sucked up, which creates a some slack in the movement of the ribbon which can thus be used to cushion sudden changes in speed as will be described later.

According to another preferred variant of the invention, the ribbon is guided by a set of deflection rollers to pass at least a second times between the applicator cylinder and the pressure at a position offset in the axial direction of these cylinders, that is to say apply images on a second column of the sheet.

According to another variant, the machine comprises at least a second ribbon, which allows you to apply the images on a third column, or even a fourth if the machine is also provided with return means for pass the second ribbon a second time. The second pass of the ribbon has the advantage of saving the ribbon because instead of placing the images shifted by a length of a bank note, we have the images at a distance of half a length, which means that when the ribbon passes the first time between the pressure cylinder and the applicator cylinder, these are the pictures, for example, odd that are applied on the sheet and when second pass of the ribbon, these are the even images that are applied. This therefore saves on the length of the ribbon.

Finally, according to another alternative embodiment, if it is necessary to apply not point images, but a whole band on the tickets, this can be easily done using the above installation replacing the buffers with annular segments whose length is equal to either the length of the sheet, or the length of the tickets if these strips must be applied over a certain length of tickets.

According to another variant, the buffer of the applicator cylinder can also be heated to get better image adhesion on sheets and reduce any deviations from temperature between the different images.

The preheating means are optional: hot air, or radiation, or infrared. These means can be composed of two parallel plates, one of which is heated located on the side of the adhesive, while the other has as function of reflecting the warmth of the first.

The invention will be described in more detail using the attached drawing in which:

Figure 1 shows a schematic perspective view of a machine according to a preferred embodiment of the invention.

Figures 2 to 4 are a partial side view of the installation to explain the operation of the machine.

The machine in question (fig. 1) has two cylinders transfer 2 and 3 receiving sheets 1 partially or totally printed on which an image 7 from a ribbon 8 must be pasted. The sheets 1 come by conventional means of a stock of leaves leaving a facility printing. Transfer cylinders 2, 3 can advantageously be suction cylinders. To the continuation of the two transfer cylinders 2 and 3, is a pressure cylinder 4 intended to receive two sheets 1. An input device 41 of the front edge in the direction of movement of the sheet 1 allows grab the sheet and drag it in the direction of displacement of the cylinder indicated by arrow F. The cylinder 4 is therefore provided with two projecting parts 42, separated by two grooves 43, one of the ends is provided with means 41 for gripping the front edge from sheet 1.

Above the pressure cylinder 4 is the applicator cylinder 5 provided with rings 51 carrying buffers 52 to apply images 7 against sheet 1.

A cylinder 6 which is in principle a cylinder suction takes over sheet 1 after its passage between the two cylinders 4 and 5 towards a storage device. Often before storing sheets 1 on which the security images 7 have been glued, the sheets 1 pass through a device cooling to cool the adhesive.

In the installation of the present invention, it is uses two coils B1 and B2 each comprising a ribbon 8, respectively 8a, provided with images 7 arranged along these ribbons so that said images, when the ribbon passes between cylinders 4 and 5 applies to the planned locations.

We will now briefly describe the passage from ribbon provided that this installation is not the only possible installation. Starting from the reel B1, two return rollers or rollers 9 and 10 allow the ribbon to be directed towards a device 11 whose use will be explained subsequently, followed by two reversing rollers 12 before switching between the preheater 13 and thereafter between the pressure cylinders 4 and 5. Then it goes between the rollers in advance 14, the second suction device 15 and by means of deflection rollers 16, 17, 18 and 19, the tape comes on the part upstream of the installation to pass a second time using rollers 20 and 21 on a suction device 11 ', between rollers reversing 12 ', between the preheating device 13 before pass again between the pressure cylinders and applicator on a second column and finally after being returned to the return rollers 22, 23, 24, on a winding reel 25. Similarly, from the reel B2, ribbon 8a, by quite devices similar, passes twice between cylinders 4 and 5 before also winding on the same reel 25. The double passage of the ribbon between the cylinders pressure and applicator saves the length of the ribbon because instead of arranging the images to apply to the tape at a distance which is equal to the distance of two consecutive images 7 on the sheet 1, we arrange the images over half a distance and when the first strand of the ribbon passes between the applicator and pressure cylinders, images, by example, odd numbers are applied and when passing the second strand of the ribbon, these are the even images which are applied. In this way, we save little almost half the length of the ribbon.

It is obvious that the spacing of the rings 51, as well that buffers 52 depends on the size of the securities the printed on sheet 1. In case of change either the sheet format or the format securities, we can either change the applicator cylinder 5, either simply change or move the rings 51 and the buffers so that there is a perfect register between the buffers and the locations where images should be applied.

It is clear that the tapes 8 and 8a used are provided with spacing between images corresponding to the format of sheet 1 and the securities la to print.

Using figures 2 to 4, we will explain now the operation of this machine.

At the start, the ribbon is registered with the sheet 1 to which the images 7 are to be transferred. To do this, the ribbon is provided in a way regular 27 marks which are read by a device 26 located after the preheating device 13 and before the ribbon comes into contact with the two pressure cylinders 4 and applicator 5. This device 26 has not been shown on the installation shown in Figure 1 so as not to unnecessarily load the drawing. Reader 26 controls the rollers back 12 and forward 14 to position ribbon correctly 8.

The preheating means 13 operate so intermittent so as not to unnecessarily preheat the ribbon. We could even heat only the images which will be applied when the ribbon passes between the two aforementioned cylinders. At the position indicated at Figure 2, preheating 13 is stopped and the ribbon is also at a standstill, register mark 27 facing the reader 26. As soon as the sheet of paper 1 approaches the line joining the two axes cylinders 4 and 5, the ribbon moves in synchronism with sheet 1 and supported images by the ribbon 8 are pushed against the sheet 1, at means of buffers 52, as can be seen in the figure 3. When the ribbon 8 starts to move, the heating 13 is activated to heat the length of the ribbon or the ribbon images to follow. In this case, this are the feed rollers 14 which drive the ribbon forward assisted by the device 15. When the last image to transfer 7 on sheet 1 in question is applied, heating is stopped, the tape also by stopping the feed rollers 14 and by activating the reversing rollers 12 assisted by the device 11 for stretching the ribbon. While the pressure cylinder 4 and applicator cylinder 5 continue their rotation to come to the position of departure for the application of images 7 on the second sheet 1 located on the pressure cylinder 4, the ribbon 8 is moved back about a length equal to the length of a sheet, repositioned using rollers 12 and 14 under the control of the reading 26 of the position of the register mark 27. During this period, the preheating 13 is stopped.

As soon as the position of cylinder 5 makes the edge front of next sheet 1 is aligned with the line of the axes of the two cylinders, the process previously explained starts again. The two elements to aspiration 11 and 15 are intended to aspirate part of the length of the ribbon 8 assisting the rollers 12 and 14 and somehow creating a slack which allows, of a share, in the event of a sudden acceleration of the strip to absorb this acceleration without causing a unwanted tension in the coil and, on the other hand, during deceleration to also be able to absorb the difference in speed by sucking inside the length of strip which continues to advance under force inertia.

According to a preferred variant of the invention, the buffers 52 can also be heated to ensure a almost constant temperature of application of images 7 on sheet 1.

It is obvious that the steps described above concerning ribbon 8 also apply to the second strand of this ribbon 8 and also to ribbon 8a since the image application work is done along a generator of the applicator cylinder, namely on four securities from a row of securities printed on the sheet.

The size of the stamps is approximately the size of the images to be applied. A setting of temperature is desirable so that the images preheated arrive at the place of application to the correct temperature. Depending on the adhesive used, and working conditions, we can not heat buffers 52 if the preheating temperature is sufficient.

According to an alternative embodiment, the installation can also be used to apply not images but whole strips on the tickets and in this case instead of having buffers as shown here we have buffers which are segments ring to apply the tape directly either on the sheet from one end to the other, or only on tickets and in this case we have need several separate annular sectors.

The preheating means 13 are composed of two parallel plates including the one located on the side of the adhesive is heated, while the other reflective the heat.

Claims (10)

1. A machine for the security printing of security paper (1a), especially banknotes, comprising a paper sheet feed device, a device for transporting the paper and a unit for applying security images (7) supported by at least one ribbon (8, 8a) which is brought into contact with the paper (1) such that these images (7) are applied at determined points on the paper (1) corresponding to the printing on the security paper (1a), the application unit comprising an applicator cylinder (5) fitted with pads (52) arranged on the periphery of the applicator cylinder in register with said determined points, cooperating with a press cylinder (4), between which cylinders the paper (1) passes, said ribbon (8, 8a) being mounted between two reels - (B1, B2) for paying out the ribbon, and (25) for winding up the ribbon - the ribbon (8, 8a) passing parallel to the path of the paper (1), the machine being fitted with a device (13) for preheating the ribbon(8, 8a) upstream of the applicator cylinder (5) so as to preheat the images (7) which will be applied to the sheet of paper (1) by simple contact of said pads (52) with the images (7) against the press cylinder (4).
2. A machine as claimed in claim 1, wherein, with a view to economizing on ribbon (8, 8a), the machine is fitted with means which allow the ribbon (8, 8a) to be made to advance in synchronism with the sheet (1) passes between the applicator cylinder (5) and the press cylinder (4), to slow down the advance of the ribbon (8, 8a) and to make it back up over a distance equal to approximately the length of a sheet, when the sheet (1) has left the applicator cylinder (5) while waiting for the arrival of the next sheet and to bring the ribbon (8, 8a) into register with the next sheet.
3. A machine as claimed in claim 2, wherein said means comprise a pair of advance rollers (14) arranged downstream of the applicator cylinder (5) causing the ribbon (8, 8a) to advance, a pair of backing-up rollers (12, 12') upstream of the preheating device causing the ribbon (8, 8a) to back up, a device (26) for reading the register marks (27) with which the ribbon (8, 8a) is provided, and means (11; 15) arranged upstream of the backing-up rollers (12, 12') and downstream of the advance rollers (14) providing assistance to said rollers when the ribbon (8, 8a) experiences a change in speed.
4. A machine as claimed in claim 3, wherein said devices (11; 15) for assisting said rollers (12,12',14) when there is a change in speed are two negative pressure boxes into which a section of ribbon (8, 8a) is sucked.
5. A machine as claimed in one of claims 1 to 4, wherein the ribbon (8, 8a) is guided by a set of turn rollers (16 to 21) so that it passes at least a second time between the applicator cylinder (5) and the press cylinder (4) in a position that is offset in the axial direction of these cylinders.
6. A machine as claimed in one of claims 1 to 5, which comprises at least a second ribbon (8a) for applying images (7) to a position that is axially offset with respect to the first ribbon (8).
7. A machine as claimed in one of claims 1 to 4, wherein the images are strips extending from one side of the security paper (1a) to the other, the pads of the applicator cylinder being annular segments the length of which corresponds to the length of the sheets (1) or of the security papers (1a).
8. A machine as claimed in one of claims 1 to 7, wherein the pads (52) of the applicator cylinder (5) are equipped with heating means.
9. A machine as claimed in claim 5, wherein the preheating means employ hot air, infra-red, or radiation.
10. A machine as claimed in claim 5, wherein said preheating means comprise two parallel plates, one of which, placed on the same side as the ribbon (8, 8a) emits heat, and the other of which, situated on the other side of the ribbon, is designed to reflect the heat emitted by the first plate.

Images