Patent Description:
Providing a substrate with holograms is a complicated process having strict requirements on the precision of the process.

The process is usually carried out in a hot foil stamping machine having a platen unit that is supplied with the substrate to be processed and a holographic foil comprising the holograms.

For a high quality result, the advancement of the holographic foil into the platen unit has to be controlled or calibrated precisely. Further, lateral displacement of the holographic foil with respect to the platen unit has to be compensated with suitable adjustment means.

Usually, hot foil stamping machines are provided with a variety of single rollers, sensors or adjustment means for the advancement and alignment of the holographic foil, but are difficult to assemble as the many rollers, sensors, control means and adjustment means have to be mounted individually to the hot foil stamping machine.

For example, <CIT>, <CIT> and <CIT> disclose a hot foil stamping machine where the advancement and alignment of the holographic foil are performed by a variety of rollers and sensors of the machine.

It is thus the object of the invention to provide a holographic foil supplying device as well as a hot foil stamping machine that is easier to assemble and to calibrate.

For this purpose, a holographic foil supplying device for a hot foil stamping machine is provided, comprising a reel for holographic foil, an advancement system for advancing the holographic foil along a movement path in a feeding direction and a frame supporting the reel as well as the advancement system, wherein the frame comprises a mount for mounting the supplying device to the hot foil stamping machine, characterized in that the mount comprises lateral adjustment means or adjusting the position of the frame in a direction perpendicular to the feeding direction.

By having a frame that supports both the reel and the advancement system of the holographic foil supplying device, a single unit is provided that can be mounted and aligned on a hot foil stamping machine with little effort.

In particular, the mount may be the only connection of the holographic foil supplying device with the hot foil stamping machine that supports the holographic foil supplying device, i.e. which carries its weight.

Preferably, the advancement system comprises a feeding roller, a pressure roller and a motor for driving the feeding roller, wherein the feeding roller, the pressure roller and/or the motor are supported by the frame. This way, a fully functional advancement system can be provided on the frame.

For driving the feeding roller, the motor and the feeding roller may each comprise a pulley, wherein the pulleys are connected by a belt for torque transmission or any other suitable advancement system.

In order to achieve a compact device, the motor is located on a bottom side of the frame and the reel and/or the feeding roller is located at a top side of the frame.

The advancement system comprises a control loop for controlling the advancement of the holographic foil, in particular the control loop being a closed control loop. This way, the precision of the advancement movement can be improved significantly. The advancement affects the position of the hologram(s) on the stamped substrate along the foil feeding direction.

For a reliable and agile control loop, the advancement system may comprise an alignment sensor for the holographic foil, the alignment sensor being supported by the frame.

The alignment sensor may be a camera directed to a sensor section of the movement path in order to achieve a high alignment precision.

In particular, the camera is configured to detect the position of holograms on the holographic foil.

The alignment sensor may be an optical cell, optionally connected to an optical fiber, directed to the sensor section of the movement path in order to achieve a high alignment precision.

In particular, the optical cell is configured to detect the position of an ad-hoc mark printed on the holographic foil.

In order to further improve the precision of the feeding movement, a support surface, in particular a plate, is provided in the sensor section for supporting the holographic foil.

The advancement system is configured to feed the holographic foil into the hot foil stamping machine using a stop-and-go cycle synchronized with the stamping cycles of the machine. In particular, when the stamping machine is in an open configuration, the foil is advanced until it reaches its predetermined position and stops, then the machine closes to stamp, opens again, and a new cycle starts.

The holographic foil comprises a repetition of holograms or groups of holograms. The advancement of the holographic foil may be adjusted by measuring, within the sensor section, the relative positions of a hologram (or the relative positions of an ad hoc mark) across stamping cycles, until the hologram reaches the correct position on the substrate.

In a variant of the invention, the supplying device comprises a first deflection roller and a second deflection roller, wherein the sensor section is located between the first deflection roller and the second deflection roller. The deflection rollers ensure that the holographic foil assume the indented position in the sensor section.

The second deflection roller may be an exit roller, i.e. the last roller in the movement path of the supplying device.

In a further embodiment of the invention, the frame comprises at least one side portion, in particular two side portions, each side portion being located at a different side of the movement path, wherein the reel, the pressure roller, the feeding roller, the two deflection rollers, the support surface and/or an exit roller extend from the at least one side portion to the other side, in particular to the other side portion and/or wherein the motor is located between the side portions. By the use of, preferably flat, side portions of the frame, the holographic foil supplying device has a very compact design.

The other side of the one side portion may be the other side of the movement path and/or the holographic foil with respect to the side portion.

For pretensioning the holographic foil, the holographic foil supplying device may comprise a brake coupled to the reel for braking a rotational movement of the reel, wherein the reel and the brake are arranged on opposite sides of one of the side portions.

The brake may be located on same side as the pulleys. Further, the brake and/or the pulleys may be provided at the outer side of a side portion. As the mount itself comprises the lateral adjustment means, the effort in aligning the device can further be reduced. This lateral adjustment affects the position of the hologram(s) on the stamped substrate along a perpendicular to the foil feeding direction.

For example, the mount comprises a base mountable to the hot foil stamping machine and a carriage slideably connected to the base, wherein the carriage supports the frame, and wherein the lateral adjustment means is configured to position the carriage with respect to the base. A reliable and precise lateral adjustment can be achieved this way.

The carriage may be slideable horizontally and perpendicularly to the feeding direction. For example, the adjustment means comprises a screw actuating the carriage.

For above mentioned purpose, further a hot foil stamping machine for applying a hologram to a substrate is provided, comprising a platen unit, a feeding unit for feeding the substrate to the platen unit in a substrate feeding direction and at least one holographic foil supplying device, in particular as described above, for feeding a holographic foil to the platen unit in a foil feeding direction, in particular the foil feeding direction being opposite to the substrate feeding direction. This allows the usage of multiple holographic foil supplying devices.

The substrate may be cardboard or paper or any other type of sheet from material.

For example, the hot foil stamping machine comprises at least one receiving reel for the substrate, wherein the at least one supplying device is located on the same side of the platen unit as the at least one receiving reel and/or the feeding unit is located on the opposite side of the platen unit than the holographic foil supplying device, leading to a compact design.

Further features and advantages will be apparent from the following descriptions as well as the attached drawings to which reference is made. In the drawings:.

<FIG> shows a hot foil stamping machine <NUM> having a platen unit <NUM>, a feeding unit <NUM>, a receiving reel <NUM> and two holographic foil supplying devices <NUM>.

The hot foil stamping machine <NUM> is, for example, used to apply holograms to substrates, for example cardboard or paper. The hot foil stamping machine <NUM> is for example used to manufacture high quality product packages or currency bills.

The platen unit <NUM> comprises a platen as per se known that is configured to apply a hologram to a substrate <NUM> from a holographic foil, i.e. a foil containing the holograms. The transfer of the holograms from the holographic foil to the substrate <NUM> is effected by pressure and heat.

The platen unit <NUM> has a first side, in <FIG> the right-hand side, on which the feeding unit <NUM> is located.

On the second side, the left-hand side in <FIG>, the receiving reel <NUM> and the holographic foil supplying devices <NUM> are arranged. Thus, the holographic foil supplying devices <NUM> are located on the same side of the platen unit <NUM> as the receiving reel <NUM> but on the opposite side than the feeding unit <NUM>.

The feeding unit <NUM> is per se known and is configured to supply the platen unit <NUM> with the substrate <NUM> to be processed. The feeding unit <NUM> feeds the substrate <NUM> to the platen unit <NUM> in a substrate feeding direction S.

On the other side, the receiving reel <NUM> is configured to receive the substrate <NUM> exiting the platen unit <NUM>, i.e. the processed substrate <NUM> comprising the hologram.

The two holographic foil supplying devices <NUM> are configured to supply the platen unit <NUM> with a holographic foil <NUM> in a holographic foil feeding direction F.

<FIG> show one of the holographic foil supplying devices <NUM> in more detail. For simplicity, the holographic foil supplying device <NUM> is called supplying device <NUM> in the following.

The supplying device <NUM> comprises a frame <NUM>, an advancement system <NUM> and a reel <NUM> for the holographic foil <NUM>.

The holographic foil <NUM> on the reel <NUM> comprises holograms to be applied to the substrate <NUM> in the platen unit <NUM>.

The frame <NUM> comprises two side portions <NUM> and a mount <NUM> for mounting the frame <NUM> to the hot foil stamping machine <NUM>, more precisely to a mounting point <NUM> of the hot foil stamping machine <NUM>.

It is of course possible that the frame <NUM> comprises only one side portion <NUM>. In this case, the arrangement is the same as explained below solely without the second side portion <NUM>. Thus, elements described in the following as extending from one of the side portions <NUM> to the other side portion <NUM> extend, in the case of a single side portion <NUM>, from the one side portion <NUM> to the other side, i.e. the other of the movement path P and/or the holographic foil <NUM> side with respect to the side portion <NUM>.

The side of the frame <NUM> provided with the mount <NUM> is the bottom side <NUM> and the opposite side is called the top side <NUM> of the frame <NUM>.

The side portions <NUM> are flat pieces of metal or a plastic material having holes, slots and openings for mounting various parts of the advancement system <NUM> and the reel <NUM>.

The side portions <NUM> are generally identical and are arranged parallel but spaced apart to each other. The distance between the side portions <NUM> is smaller than <NUM> times the width of the holographic foil <NUM>.

The reel <NUM> is located at the top side <NUM> and extends over the top side <NUM> of the frame <NUM>.

The reel <NUM> is connected to a brake <NUM> on the outside of one of the side portions <NUM>.

The brake <NUM> is rotatably fixed to the reel <NUM> through the side portion <NUM> and is able to create a resistance for a rotatable movement of the reel <NUM>.

This is done in the shown embodiment with a gear wheel fixedly connected to the reel <NUM>. The brake <NUM> interacts with the gear wheel to alter the speed of the reel <NUM>.

The mount <NUM> comprises a base <NUM> and a carriage <NUM>.

The base <NUM> is fixed to the hot foil stamping machine <NUM> at the mounting point <NUM>.

The carriage <NUM> is mounted slideably in the base <NUM>, wherein the frame <NUM> is fixed to the carriage <NUM>. This way, the frame <NUM> is slideable with respect to the carriage <NUM> and the platen unit <NUM> as well.

The mount <NUM> is the only support of the supplying device <NUM> at the hot foil stamping machine <NUM> that carries its weight.

The advancement system <NUM> has a motor <NUM>, an alignment sensor <NUM>, four rollers <NUM>, <NUM>, <NUM> and <NUM> and a plate <NUM>.

The rollers <NUM>, <NUM>, <NUM>, <NUM> and the reel <NUM> are rotatably mounted in the frame <NUM> extending from one of the side portions <NUM> to the other, thus spanning the distance between the two side portions <NUM>.

The motor <NUM> and the alignment sensor <NUM> are arranged between the side portions <NUM> and fixed thereto, wherein the motor <NUM> is located at the bottom side <NUM> in the shown embodiment.

The rollers <NUM>, <NUM> are a pair of driving rollers being a feeding roller <NUM> and a pressure roller <NUM>.

On the outer side of one of the side portions <NUM>, i.e. not between the side portions <NUM>, two pulleys <NUM> are provided, each corresponding to either one of the feeding roller <NUM> or the motor <NUM>.

The pulley <NUM> of the feeding roller <NUM> is rotatably fixed to the feeding roller <NUM> through the side portion <NUM>, e.g. by an axis.

The other pulley <NUM> is rotatably fixed to an output shaft of the motor <NUM> through the side portion <NUM>.

The pulleys <NUM> are connected via a belt <NUM> so that torque created by the motor <NUM> can be transmitted to the feeding roller <NUM> via the pulleys <NUM> and the belt <NUM>. Of course, the pulleys <NUM> may be driven by any other suitable advancement system as well.

The pressure roller <NUM> is not driven.

The brake <NUM>, the pulleys <NUM> and the belt <NUM> are located on the same side of the frame <NUM>, i.e. outside of the same side portion <NUM>.

For the sake of simplicity, the belt <NUM> and the pulley <NUM> associated with the motor <NUM> have been omitted in <FIG>.

The rollers <NUM> and <NUM> are deflection rollers <NUM>, <NUM> and not driven.

The deflection rollers <NUM>, <NUM> are arranged in a distance from one another, wherein the plate <NUM> is located between the deflection rollers <NUM>, <NUM>.

More precisely, the plate <NUM> comprises a support surface <NUM> being oriented in the direction of the deflection rollers <NUM>, <NUM>. The support surface <NUM> is aligned within a plane tangential to the deflection rollers <NUM>, <NUM> in a side view.

The section between the deflection rollers <NUM>, <NUM>, more precisely the section above the support surface <NUM> defines a sensor section <NUM> for the alignment sensor <NUM>.

In the sensor section <NUM>, the holographic foil <NUM> is supported by the plate <NUM>, more precisely the support surface <NUM>.

The alignment sensor <NUM> comprises a camera <NUM> and in the shown embodiment a control unit <NUM>.

The camera <NUM> is capable of detecting holograms on the holographic foil <NUM> and is directed to the sensor section <NUM>.

The control unit <NUM> is electronically connected to the camera <NUM> and the motor <NUM> for controlling the function of the motor.

The control unit <NUM> comprises a closed control loop for controlling the movement of the motor based on the data received by the camera <NUM>.

The rollers <NUM>, <NUM>, <NUM>, <NUM> and the plate <NUM> define a movement path P of the holographic foil <NUM>.

The movement path P starts at the reel <NUM> and runs between the feeding roller <NUM> and the pressure roller <NUM> to the deflection roller <NUM>. The movement path P then passes the support surface <NUM> of the plate <NUM> and continues to the deflection roller <NUM>. The deflection roller <NUM> can be regarded as an exit roller of the supplying device <NUM>.

Thus, the movement path P lies between the side portions <NUM> so that the side portions <NUM> are located at different sides of the movement path P seen in a top view (<FIG>).

As seen in the side view (<FIG>), the deflection rollers <NUM>, <NUM> are located on the opposite side of the pathway P as the plate <NUM>.

During operation of the hot foil stamping machine <NUM> the supplying device <NUM> feeds the holographic foil <NUM> to the platen unit <NUM> by activating the motor <NUM>. Accordingly, the feeding roller <NUM> is driven leading to a movement of the holographic foil <NUM> in the holographic foil feeding direction F along the movement path P. The advancement movement is adjusted or controlled via the alignment sensor <NUM> and the control unit <NUM>.

The camera <NUM> detects the absolute location of a hologram on the holographic foil <NUM> in the sensor section <NUM>, e.g. by comparing the location to the location of a marking on the support surface <NUM>. According to the detected location of the hologram, the following advancement movement is adjusted in length, i.e. the motor <NUM> is actuated for a slightly shorter or longer period of time.

Lateral adjustment of the location of the holographic foil <NUM>, i.e. adjustment in the plane of the holographic foil <NUM> but perpendicular to the holographic foil feeding direction F, is done manually using the mount <NUM> of the supplying device <NUM>. The carriage <NUM> with the attached frame <NUM> that supports the reel <NUM>, the rollers <NUM>, <NUM>, <NUM>, <NUM>, the motor <NUM> and the alignment sensor <NUM>, can be moved perpendicularly to the feeding direction F with respect to the rest of the hot foil stamping machine <NUM>, especially with respect to the platen unit <NUM>. This is done by sliding the carriage <NUM> relative to the base <NUM> which is fixedly mounted on the mounting point <NUM> of the hot foil stamping machine <NUM>. The movement can be performed by adjustment means <NUM>, for example by a screw <NUM> of the mount <NUM> that engages the carriage <NUM>.

Thus, the supplying device <NUM> is a compact device that can be mounted to the hot foil stamping machine <NUM> with a single mount <NUM> and provides means for adjustment in the lateral direction perpendicular to the feeding direction F and along the feeding direction F. Therefore, the supplying device <NUM> can be easily and quickly mounted to the hot foil stamping machine <NUM> and rapidly aligned with respect to the platen unit <NUM>.

Claim 1:
Holographic foil supplying device for a hot foil stamping machine (<NUM>) comprising a reel (<NUM>) for holographic foil (<NUM>), an advancement system (<NUM>) for advancing the holographic foil (<NUM>) along a movement path (P) in a feeding direction (F) and a frame (<NUM>) supporting the reel (<NUM>) and the advancement system (<NUM>), wherein the frame (<NUM>) comprises a mount (<NUM>) for mounting the holographic foil supplying device (<NUM>) to the hot foil stamping machine (<NUM>),
characterized in that the mount (<NUM>) comprises lateral adjustment means (<NUM>) for adjusting the position of the frame (<NUM>) in a direction perpendicular to the feeding direction (F).