DEVICE FOR PRECISE FOIL EMBOSSING AND METHOD

Description

Field of the Invention

[0001] This invention relates to an apparatus and a process for transferring images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses from a stamping foil with registration accuracy to a Z flexible substrate such as paper, polymer, flexible laminates, woven or non-woven and combination of these in roll to roll form.Background

[0002] In today's competitive consumer market, decorative packaging has become very important and is used as a marketing tool to attract the attention of potential shoppers. It is known in the art to create or transfer artistic text, latent images, holograms, prints or Fresnel lenses on a particular area of a film or laminate. Such Fresnel lens films are known to be used for packaging to make them more attractive.

[0003] Further, it is desired and well-known in the art to configure such artistic text, latent images, holograms, prints or Fresnel lenses by lamination with the film having artistic text, latent images, holograms, prints or Fresnel lens to another substrate such as another polymeric film, or fibrous substrates such as paper, paper board or synthetic fibrous substrates.

[0004] While incorporating artistic text, latent images, holograms, prints or Fresnel lenses over substrates using hot or cold stamping process known in the art, over a specific area significant portion of stamping foil is wasted and also the stamping does not transfer the lenses / images exactly over the desired location on the substrate consistently and need to be corrected every time. This leads to reduction in production speed and not a high quality product as desired.

[0005] A process for transferring a foil print from a foil on to a substrate and an apparatus for carrying out that process are known from DE 32 10 551 C2. The process and the apparatus disclosed in said document are suitable for virtually endlessly impressing a substrate in the form of a flexible web of material, with a print, in the direction of forward feed movement of the substrate. The substrate may be for example a magnetic strip on a ticket or a decorative endless strip which covers a corresponding print portion, that is to say a ticket or the like, in the direction of transportation movement of the substrate from one edge of the corresponding desired location as far as the oppositely disposed edge thereof.

[0006] EP 0 433 575 A1 discloses an apparatus for gluing marks from a film supplied on a carrier tape facing a substrate onto the substrate using a stamp, whose work cycle is divided into an adhesive phase and a feed phase, said apparatus comprising devices for unwinding and winding up the carrier tape and devices for feeding and removing the substrate, wherein in at least one gluing station the carrier tape and the substrate are passed through between a stamp cylinder and an impression cylinder, wherein in the at least one gluing station the substrate has a predetermined feed speed, and wherein the stamp cylinder has at least one radially raised smooth stamp, the stamp surface of which is part of a cylinder jacket which is concentric with the stamp cylinder and runs on the impression cylinder. A correspondent process is also provided therein. Therefore said document describes an apparatus and a process according to the respective preambles of claims 1 and 4 of the present invention.Summary of the Invention

[0007] An apparatus for transferring images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses from a stamping foil with registration accuracy to a flexible substrate in roll to roll form according to the present invention is defined in appended claim 1.

[0008] According to the present invention images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses are provided by means of a stamping foil on a flexible substrate, in registered relationship at a desired location. More specifically, it is possible to provide an accurately defined and exact association of the foil images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses to the desired portions of the substrate to be stamped in roll form. The rotary angular position of the stamping punch segments of stamping roller, and a predetermined identification of desired location of the substrate and stamping foil is synchronized to each other by means of a regulating device. Multiple high speed and high resolution optical sensors are positioned to sense the position of substrate, stamping foil, stamping punch and stamped substrate or foil, which provide input to a regulating device. The identification on the substrate or each desired location of the substrate involves suitable print marks which are detected by the corresponding optical sensors and position data from these sensors is continuously fed to the regulating device to generate controlling instructions to various drives.

[0009] The substrate for stamping is fed from an unwind roll of the substrate through a feed roller. An adjusting roller is provided on the rewind side of stamping station, which acts in tandem with feed roller to keep the speed and tension of the substrate constant.

[0010] A supply device may be used with the apparatus to provide a continuous length of substrate. A device for applying a patch of primer or an adhesive on the substrate in registered relationship or all over may also be provided to enhance bonding strength.

[0011] The stamping foils are fed from an unwind roll of the stamping foil through a feed roller. An adjusting roller is provided on the rewind side of stamping station, which act in tandem with feed roller to keep the tension of the foil constant and to adjust the foil with respect to pitch of stamping punch and substrate for accurate stamping position on the substrate.

[0012] Print marks on the foil or the prints thereon are sensed and determined by optical sensors and adapted by the regulating device. The drive of the feed roller and adjusting roller is controlled by motors, in particular servo motors, under instructions from regulating device, which continuously rotate the rollers clockwise or anticlockwise to adjust the stamping foil according to position of flexible substrate so that the stamping foil falls exactly over the desired location on the substrate, where the stamping is required.

[0013] The stamping roller provided at stamping station is driven by a motor, in particular a servo motor, connected to regulating device. An optical sensor is provided to sense the position of stamping punch on the stamping roller. The position data of the stamping punch is sent to regulating device, which in turn controls rotation of the motor to adjust the stamping roller to register it with respective positions of substrate. A pressure roller is also provided against the stamping roller to provide necessary pressing of foil over substrate for stamping.

[0014] In addition to these optical sensors described above, another optical sensor is provided to monitor the used stamping foil. The positional data of the stamped portion of the foil is detected and the data is sent to the regulating device to fine-tune the position of the stamping foil. The positional data is detected by the sensor and sent to regulating device, which in turn control the feed rollers and adjusting rollers to correct the position of the stamping foil with respect to substrate.

[0015] Another sensor i.e. high-resolution, high-speed optical sensor such as an inspection camera is provided to detect the variation in the stamped substrate. The camera ensures that the stamping on the substrate is done on the accurate location where it is required. In case any variation in stamping is detected from the desired stamping location, then variation data is sent to regulating device for further correction in the position of different components viz. stamping foil and stamping roller.

[0016] According to present invention, a digital regulating device is provided for control and operation of various components of the system, as described above. The regulating device is connected on its input side to different optical sensors and on its output side to different control drives for feed rollers, adjusting rollers and the stamping roller. The data related to diameter of rollers and pitch are pre-determined and fed by user into the regulating device. There is at least one optical sensor associated with each of substrate, stamping foil and stamping roller, on unwind side of stamping station and at least one optical sensor associated with stamped substrate and used stamping foil on rewind side of stamping station are provided, which are connected to said regulating device. The sensor associated with the flexible substrate on unwind side, sends input to regulating device about the pitch and corresponding position of the substrate which is going to be stamped. Based on the positional data sent by the optical sensor associated with substrate, position of the stamping punch is adjusted. Similarly, the markings on the stamping foil are detected by means of the optical sensor for stamping foil on the unwind side and the data corresponding to the detected markings are fed to the regulating device. The position data of the stamping punch is sensed by optical sensor associated with stamping roller and sent to the regulating device. Based on input from optical sensors associated with substrate and stamping foil on unwind side of stamping station, the regulating device calculates, compares and controls the rotation of the stamping roller drive which adjusts the position of stamping punch by clockwise or anticlockwise rotation of stamping roller to ensure that the stamping is done exactly at required position on the substrate when it comes under stamping roller.

[0017] The regulating device may be a PLC (programmable logic controller) or a computer-based system capable of receiving multiple inputs from the sensors calculating, comparing and providing outputs for corresponding controlling devices such as servo motors according to the algorithms programmed by user.

[0018] At least an optical sensor is provided on the rewind side of the stamping station to sense the corresponding position of used stamping foil after stamping and before rewind and in case there is any deviation, then the deviation data is sent to regulating device for additional corrective measures i.e. by clockwise or anticlockwise rotation of stamping foil feed roller and adjusting roller servo drives. This happens continuously in close loop in addition to the initial adjustment for synchronisation of substrate, stamping foil and stamping roller to achieve even better positional accuracy of stamping.

[0019] In addition to above, at least a high-resolution, high-speed optical sensor such as an inspection camera is provided on the rewind side of the stamping station to sense the corresponding position of stamped substrate after stamping before rewind. In case there is any deviation, then the deviation data is sent to the regulating device for additional corrective measures i.e. to fine-tune the position of stamping punch and stamping foil. According to another aspect of invention a process for transferring prints, latent images, Fresnel lenses, holograms or sterling lenses from a stamping foil foil with accurate registration on a flexible substrate in roll to roll form is defined in appended claim 4.

[0020] According thereto the substrate is fed from an unwind by a pair of feed rollers, which act in tandem with another pair of rollers i.e. adjusting rollers, which help in keeping the line speed and tension of the substrate constant. Input data for repeat pitches, eyermarks / print marks on the substrate is fed to the regulating The input from sensor is fed to the regulating device, which in turn adjusts the position of stamping punch on the stamping roller with respect to position on the substrate by clockwise or anticlockwise rotation of stamping roller to ensure that the stamping is done exactly at same required position on the substrate at the corresponding sensed pitch.

[0021] Position of stamping foil is also corrected with respect to corresponding position of substrate and stamping punch. Eye mark on stamping foil is sensed over the foil feed roller by a high speed and high-definition optical sensor. The drive to the feed roller is controlled by regulating device as described above. The drive to the feed roller and adjusting roller is driven respectively by a motor, in particular a servo motor, which continuously rotates the rollers clockwise or anticlockwise ensuring that the punching position on stamping foil matches with corrected position of the stamping punch so that the stamping foil falls exactly over the location on the substrate where the stamping is required which also coincides with the stamping punch pressure.

[0022] The stamping foil is supplied from an unwind roll, and passes through feed rollers and adjusting roller working in tandem to pull the foil back and forth to correct the position of stamping foil with respect to eye-mark on substrate and stamping punch position. The stamping foil coming out of the feed roller passes over the substrate under stamping roller. Both feed and adjusting rollers work in tandem such that the tension of stamping foil between these units, passing between the substrate and the stamping roller remain constant irrespective of the continuous correction in stamping foil position taking place to match the location on substrate, stamping punch and the stamping foil.

[0023] Used stamping foil after the stamping is continuously monitored by sensor provide on rewind side which detects the pitch and / or centre of the stamped out part with respect to corresponding eye mark on the foil, which is fixed and if there is any deviation that deviation data is sent to the regulating device and based on this deviation data the position of the stamping foil is further continuously corrected to provide accurate stamping.

[0024] Stamped substrate is also sensed by a high-speed and high-resolution optical sensor such as an inspection camera provided on rewind side of stamping station, which checks that the stamping is performed at desired location, and data related to that sensing is sent to the regulating device. In case of any deviation, correction measures i.e. adjusting the position of stamping foil and stamping punch are performed to ensure that the stamping is done on accurate location.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further details, features and advantages are apparent from the following description of embodiments of the apparatus according to the invention for carrying out the process according to the invention, which are illustrated in the drawings in which: FIG. 1 is a view of a portion of a substrate to be provided with prints, latent images or Fresnel lenses in an accurate register relationship, and FIG. 2(a) shows a substrate according to an embodiment of present invention and Fig 2(b) stamping foil having stamping foil transfer areas with prints, latent images or Fresnel lenses having efficient utilization of foil; FIG. 3 shows a block diagram of the apparatus for applying prints, latent images or Fresnel lenses to a flexible substrate in roll form; and FIG. 4 is showing a section of stamping roller with stamping punches as is used in the apparatus shown in FIG. 3. DESCRIPTION OF THE PRESENT INVENTION

[0026] For a thorough understanding of the present invention, reference is made to the following detailed description in connection with the above-mentioned drawings. Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention.

[0027] FIG. 1 shows a portion of a flexible substrate (110) which has selective desired locations (112) for stamping. Each desired location (112) is registered with respect to an eye mark (111) and at a spacing A or pitch. The prints, latent images or Fresnel lenses are to be provided in accurately registered relationship with eye mark over the desired location (112). The eye mark is a pre-printed text, image or any other reference mark available on the substrate. The line speed of substrate (110) from unwind is kept constant and the eye-mark (111) is detected by an optical sensor (160) and the eye-mark sensing information is sent to a digital regulating device (158). The optical sensor is a high-resolution and high-speed sensor capable of capturing and transmitting information at high line speeds of the substrate (110).

[0028] FIG. 2(a) shows a portion of the substrate (110) with pitches A of the desired locations, where stamping of images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses are required.

[0029] Data related to eye mark pitches on the substrate is initially fed to the regulating device (158) by user and once the stamping process starts it is automatically sensed by optical sensor and fed to the regulating device for necessary corrections.

[0030] Fig 2(b) shows a stamping foil (116) with transfer areas (118) having prints, latent images or Fresnel lenses which are required to be transferred over desired locations (112) on the flexible substrate (110) in registered relationship. The pitch of transfer area (118) on stamping foil (118) may be equal or less than the pitch A of the desired locations (112) on the substrate (110) i.e. pitch A is significantly lesser than the pitch of transfer areas (118) leaving gaps between two consecutive transfer areas (118) too large and the stamping foil (116) length is wasted. To avoid waste and to efficiently use the stamping foil (116) the pitch on the stamping foil (116) is reduced to leave minimum required gap between the two consecutive transfer areas (118).

[0031] In case of specific transfer areas (118), which in the direction of transportation movement of the stamping foil (116) are at a spacing from each other, said spacing or pitch corresponds to the stamping punch (137) and to the spacing of surface portions of adjacent print portions (112) on the substrate (110) thereof. If the flexible substrate (110) has more than one rows of printed portions (112), the stamping foil (116) also required to be configured with corresponding transfer areas (118). During the process of stamping, the forward speed of the stamping foil (116) is either kept slower than that of substrate (110) or stamping foil (116) is pulled back and forth to adjust transfer area (118) such that the transfer area (118) of the stamping foil (116) exactly overlaps the desired location (112) on the substrate.

[0032] The substrate (110) and stamping foil(116) start moving at same speed but since the stamping foil (116) needs to travel less distance than the substrate (110) due to smaller pitch on the stamping foil (116) than the pitch A on the substrate (110), the stamping foil (116) is pulled back while substrate (110) is still moving forward. The stamping foil (116) is again made to move forward in tandem with the substrate (110) at the same speed to finally stop at precise registration with the substrate (110), when the substrate stops after covering pitch A. This is done to avoid effect of inertia causing overrun.

[0033] FIG. 3 shows an apparatus (128) for applying prints, latent images or Fresnel lenses (see FIG. 2) from a stamping foil (116) to a flexible substrate (110) in roll form. The flexible substrate (110) is provided from an unwind roll (140) and pulled off the unwind roll (140) by at least a pair of feed rollers (132A) and adjusting rollers (132B) provided on unwind and rewind side of the stamping station (134) respectively and fed to a stamping station (134). Stamping station comprises of a stamping roller (136) and a pressure roller (120) provided under stamping roller (136).

[0034] The line speed of substrate (110) is kept constant and eye-mark (111) or any other registration marks situated on substrate are detected by an optical sensor (160). The sensor (160) is a high speed and high resolution optical sensor such as a high resolution camera or photovoltaic cell

[0035] The line speed data of the substrate is fed to the regulating device from feed roller drive as R.P.M and diameter of the driven feed roller is already fed in the regulating device. This speed data is used to adjust the speed of the stamping foil (116). The input from optical sensor (160) regarding position of eye mark on the substrate (110) is fed to the regulating device (158). The adjusting rollers (132B) are provided on rewind side of the stamping station, act in tandem with feed rollers (132A) to keep the tension of the substrate uniform throughout the stamping process. A device tension sensor (135) for measurement of tension is provided between the feed rollers (132A) and adjustment rollers (132B), which measures tension in the substrate and sends signals to the regulating device. If at any instance tension of the substrate measured by the device (135) is below a present value, the regulating device sends signals to drive of adjusting rollers and speed of adjusting rollers (132B) increased subsequently to increase the tension in the substrate. On the other hand if tension of the substrate increases at any instance the regulating device sends signal again to the drive of adjusting roller and speed of the adjusting rollers (132B) is decreased. This happens continuously in close loop to maintain the tension in the substrate (110).

[0036] The stamping foil (116) is provided from an unwind roll (142). The stamping foil (116) is drawn off the unwind roll (142) by the feed rollers (144A) and fed to a stamping station (134). Another set of rollers i.e. adjusting rollers (144B) are provided on rewind side of the stamping station, which act in tandem with feed rollers (144A) to pull the stamping foil (116) forward or backward to adjust the stamping foil (116) according to the corresponding pitch on the substrate (110). As the feed rollers (144A) and adjusting rollers (144B) rotate continuously in clockwise and anticlockwise direction to adjust the stamping foil (116), an accumulator (130) or similar arrangement may be provided to accommodate movement of stamping foil (116) and maintain tension in the stamping foil (116). An accumulator driven by pneumatic actuator may be provided for the purpose.

[0037] According to present invention, the eye-mark (111) or any other registration marks situated on the stamping foil (116) are detected by another sensor (162) associated with the stamping foil. The sensor (162) is a high-speed and high-resolution optical sensor such as a high resolution camera or photovoltaic cell. The input from the sensor (162) regarding position of eye mark on the stamping foil (116) is fed to the regulating device (158), which in turn controls the feed rollers (144A) and the adjusting rollers (144B) and adjusts the position of the stamping foil (116) by clockwise or anticlockwise rotation of feed rollers (144A) and adjusting rollers (144B) in tandem to ensure that prints, latent images or Fresnel lenses come exactly over the desired location (112) on the substrate (110) at the corresponding sensed pitch.

[0038] A stamping roller (136) with stamping punches (137) is configured in such a way that the stamping foil (116) and the substrate (110) pass under the roller. The substrate (110) is pressed by a pressing roller (120). The stamping roller (136) is driven by a servo motor and may also be fitted with a rotary encoder. The diameter and angular pitch of the stamping punches (137) are fed into the regulating device (158). At least an optical sensor (164) senses the edge of the stamping punch (137) and sends data to the regulating device (158). The regulating device (158) compares and calculates the rotary corrections required in the stamping roller (136) to register the stamping punch (137) with the corresponding desired location (112) and transfer areas (118) on the substrate (110) and stamping foil (118), respectively. The backup pressure for stamping is provided by up movement of the pressure roller (120). The stamping punches (137) are heated to the desired temperature required for transfer from the stamping foil (116), by electric heaters, hot oil circulation or any other suitable means which are known in the art.

[0039] According to the invention at least one sensor (168) associated with used stamping foil on rewind side, is provided after stamping station to sense the eye mark or registration mark and transferred impression / portion on used stamping foil (116). The sensor (168) is a high-speed and high-resolution optical sensor that detects the transferred portion (118) location / pitch with respect to the eye-mark (111) location / pitch on the used stamping foil (116). The sensor (168) uses a reference on the transferred portion such as centre or periphery of the transferred portion and analyses it with respect to eye-mark on the foil. If there is any deviation from the expected relation with respect to eye-mark it sends the information to the regulating device for necessary correction by adjusting feed roller (144A) and adjusting roller (144B). The correction is to further improve the accuracy of the stamping locations on the substrate (110). Another sensor (166) associated with stamped substrate is also provided to check the accuracy of stamping on the substrate. In case, there is any deviation from the desired stamping location, the deviation data is sent to the regulating device (158) by the sensor and correction measure are taken by the regulating device to correct such deviations by adjusting the stamping foil and stamping punch.

[0040] The regulating device (158) is connected on the input side to different sensors such as optical sensors, rotary encoders, tension sensor, pressure sensor and on output side to different drives which are driven by servo motors. The sensors provide input from various locations as described above in real-time All the drives may be fitted with servo motors, which are controlled by output from the regulating device based on input from the sensors and set relationship between various parameters. The regulating device (158) takes inputs from the sensing devices (160, 162, 164, 166, 168 and 135) and based on different data and set relationship and adjusts the stamping foil (116) with the help of feed rollers (144A) and adjusting rollers (144B) and the corresponding positions of stamping punch (137) by means of the servo motor to ensure stamping in accurate registration. The stamping roller (136) and stamping foil (116) are adjusted in a defined manner in relation to the flexible substrate (110).

[0041] The stamping roller (136) of a length corresponding to the width of the substrate (110) is provided with stamping punches (137) which are equidistantly spaced from each other in the outer surface of the stamping roller (136). The spacing between adjacent stamping punch (137) precisely corresponds to the pitch of the print portions (112) of the flexible substrate (110) which are configured in a row one behind the other (see FIG. 1).

[0042] As already discussed, the stamping roller (136) is driven by servo motor which enables it to rotate clockwise or anticlockwise to adjust the position of stamping punch (137). It is contemplated that, the pitch of the stamping punch may not be exactly same as the pitch of the desired location (112) of the substrate (110). In that case the stamping roller is adjusted in such a manner that the stamping punch falls precisely at exact position of the desired location (112) of the substrate (110) and the transfer areas (118) of the stamping foil (116).

[0043] The sensors (168, 166), which are provided on the rewind side of stamping station, detect the accuracy of the stamping and send the accuracy data to the regulating device. Based on the accuracy information corrective measures are taken by the regulating device instantly. Therefore, the sensors on the rewind side in combination with various sensors on unwind side and different drives form a close loop mechanism. The sensor (168) on rewind side of the stamping station form close loop with the sensor (162) on the unwind side of the stamping station and the sensor (166) on rewind side of the stamping station form close loop with the sensors (162 and 164) on the unwind side of the stamping station. Due to this close loop mechanism any error in stamping is corrected continuously without waste of foil or substrate.

[0044] A supply device (not shown) may be used with the apparatus to provide a continuous length of substrate. A device for applying a patch of primer or an adhesive on the substrate in registered relationship or all over may also be provided to enhance bonding strength.

[0045] After foil prints, latent images or Fresnel lenses have been stamped out on the flexible substrate (110), a rewind roll (154) is provided for collection of stamped flexible substrate (110). At the same time the used stamping foil (116) is also wound on to a rewind roll (156).

[0046] Although the invention is explained with specific reference to servo motors to run the different drives, it may be contemplated that stepper motors and like devices may be used for the purpose.

[0047] The present invention removes the drawbacks of inaccurate registration due to varying speed of different rollers in the system and inherent inaccuracies in printing and manufacturing process of the substrate, stamping foil and stamping roller. The use of high-resolution and high-speed sensors provides continuous precise data to the regulating device which results in the continuous correction in the corresponding position of stamping punch and stamping foil to match the location on substrate. This provides accurate registered transfer of prints, latent images or Fresnel lenses on the substrate with efficient utilization of stamping foil.

Claims

1. An apparatus for transferring images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses by stamping from a stamping foil (116) with accurate registration on a flexible substrate (110). in roll to roll form, the apparatus comprising: a first unwind roll (140) to provide the flexible substrate (110) which is pulled off the first unwind roll (140) by at least a pair of flexible substrate feed rollers (132A) and flexible substrate adjusting rollers (132B) working in tandem; a second unwind roll (142) to provide the stamping foil (116) which is drawn off the second unwind roll (142) by at least a pair of stamping foil feed rollers (144A) and stamping foil adjusting rollers (144B) working in tandem; a stamping station (134) having a stamping roller (136) with stamping punches (137) provided on the outer surface of the stamping roller (136) and a pressing roller (120) provided against the stamping roller (136) to provide necessary pressing of the stamping foil (116) over the flexible substrate (110) for stamping; a tension sensor (135); a multiplicity of sensors comprising an unwind side flexible substrate sensor (160), an unwind side stamping foil sensor (162), a stamping punch sensor (164), a rewind side flexible substrate sensor (166), and a rewind side stamping foil sensor (168) to sense the respective positions of the flexible substrate (110), the stamping foil (116) and the stamping roller (136); a digital regulating device (158) configured to take input from the multiplicity of sensors, to calculate, to compare and to control the rotation of drives of the flexible substrate feed rollers (132A), the flexible substrate adjusting rollers (132B), the stamping foil feed rollers (144A), the stamping foil adjusting rollers (144B), and the stamping roller (136) to adjust the position of the stamping foil (116) and the stamping punch (137) by clockwise or anticlockwise rotation of their respective drives; a first rewind roll (154) provided for collection of stamped flexible substrate (110); and a second rewind roll (156) for collection of used stamping foil (116), wherein the substrate feed rollers (132A), the flexible substrate adjusting rollers (132B), the stamping foil feed rollers (144A), the stamping foil adjusting rollers (144B), and the stamping roller (136) are configured to be driven by the drives, which are respective motor devices controlled by the digital regulating device (158), wherein the diameter and rotational speed of the flexible substrate feed rollers (132A) and the flexible substrate adjusting rollers (132B) are configured to be fed to the digital regulating device (158) to determine the speed of the flexible substrate (110). wherein the stamping foil feed rollers (144A) and the stamping foil adjusting rollers (144B) are rotatable clockwise or anticlockwise in tandem with each other to adjust the position of stamping foil (116) with respect to a corresponding sensed registration mark (111) on the flexible substrate (110). wherein the stamping roller (136) is rotatable clockwise or anticlockwise by the respective motor device which is configured to be controlled by the digital regulating device (158), wherein the unwind side flexible substrate sensor (160) associated with the flexible substrate (110) is configured to sense the pitch on the flexible substrate (110) and to send the information to the digital regulating device (158); wherein the unwind side stamping foil sensor (162) associated with the stamping foil (116) is configured to sense a registration mark on the stamping foil (116) corresponding to the registration mark (111) on the flexible substrate (110) and to send the information to the digital regulating device (158); wherein the stamping punch sensor (164) associated with stamping roller (136) is configured to sense the position of the stamping punch (137) corresponding to the registration mark (111) on the flexible substrate (110) and to send the information to the digital regulating device (158), characterised in that the sensors of the multiplicity of sensors are high-speed and high-resolution optical sensors, in that the tension sensor (135) is provided between the flexible substrate feed rollers (132A) and the flexible substrate adjustment rollers (132B), the tension sensor (135) being configured to measure the tension in the flexible substrate (110) and to send signals to the digital regulating device (158) to maintain constant tension in the flexible substrate (110) by means of the flexible substrate feed rollers (132A) and the flexible substrate adjustment rollers (132B) using data received from the tension sensor (135) ; in that the rewind side flexible substrate sensor (166) is provided after the stamping station (134) to sense the accuracy of transferred images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses stamped on the flexible substrate (110) and to send variation data to the digital regulating device (158), and in that the rewind side stamping foil sensor (168) is provided after the stamping station (134) to sense the registration mark and transferred impression or portion on used stamping foil (116) and to send the information to the digital regulating device (158).

2. The apparatus as claimed in claim 1, wherein the flexible substrate feed rollers (132A), the flexible substrate adjusting rollers (132B), the stamping foil feed rollers (144A), the stamping foil adjusting rollers (144B), and the stamping roller (136) are driven by servo motors controlled by the digital regulating device (158).

3. The apparatus as claimed in claim 1, wherein the digital regulating device (158) is a PLC, which means a programmable logic controller, or a computer-based system capable of receiving multiple inputs from the sensors, calculating, comparing and providing outputs for the respective drives of the flexible substrate feed rollers (132A), the flexible substrate adjusting rollers (132B), the stamping foil feed rollers (144A), the stamping foil adjusting rollers (144B), and the stamping roller (136).

4. A process for transferring images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses from a stamping foil (116) with accurate registration on a flexible substrate (110) in roll to roll form, the process comprising the steps of: providing a flexible substrate (110) from a flexible substrate unwind roll (140), the flexible substrate (110) being pulled by at least a pair of flexible substrate feed rollers (132A) and flexible substrate adjusting rollers (132B) working in tandem reading positional data of a registration mark (111)on the flexible substrate (110) by an unwind side flexible substrate sensor (160) and sending the positional data to a digital regulating device (158); adjusting a stamping punch (137) on a stamping roller (136 of a stamping station (134) according to the positional data of the registration mark (111) on the flexible substrate (110); providing a stamping foil (116) from a stamping foil unwind roll (142), the stamping foil (116) being drawn off by at least a pair of stamping foil feed rollers (144A) and stamping foil adjusting rollers (144B) working in tandem; adjusting the corresponding positions of the stamping foil (116) with respect to corresponding position of the flexible substrate (110) and the stamping punch (136); transferring images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses from the stamping foil (116) to the flexible substrate (110) at the stamping station (134) by stamping; and collecting the flexible substrate (110) on a first rewind roll (154) and used stamping foil (116) on a second rewind roll (156), wherein the stamping foil (116) is pulled back and forth by the stamping foil feed rollers (144A) and the stamping foil adjusting rollers (144B) to adjust position of the stamping foil (116) with respect to corresponding position on the flexible substrate (110), wherein the unwind side flexible substrate sensor (160) associated with the flexible substrate (110) senses the registration mark (111) on the flexible substrate (110) and sends the information to the digital regulating device (158), wherein a corresponding pitch on the stamping foil (116) is detected by an unwind side stamping foil sensor (162) and the information is sent to the digital regulating device (158) to adjust the stamping foil (116) with respect to flexible substrate (110), wherein the position of the corresponding stamping punch (137) is sensed by a stamping punch sensor (164) connected to the digital regulating device (158) and adjusted with respect to flexible substrate (110), characterised in that tension in the flexible substrate (110) is measured by a tension sensor (135) provided between the flexible substrate feed rollers (132A) and the flexible substrate adjustment rollers (132B), the flexible substrate feed rollers (132A) and the flexible substrate adjustment rollers (132B) work in tandem to maintain constant tension in the flexible substrate (110) using data received from the tension sensor (135), in that a rewind side flexible substrate sensor (166) on the rewind side of the stamping station (134) detects a variation in the position of stamping on the flexible substrate (110) by sensing the accuracy of transferred images, barcodes, optical patterns, latent images, Fresnel lenses, holograms or sterling lenses stamped on the flexible substrate (110) and by sending variation data to the digital regulating device (158), in that a rewind side stamping foil sensor (168) senses a registration mark and transferred impression or portion on used stamping foil (116) and sends variation data to the digital regulating device (158) for further correction through the stamping foil feed rollers (144A) and the stamping foil adjusting rollers (144B), and wherein the unwind side flexible substrate sensor (160), the unwind side stamping foil sensor (162), the stamping punch sensor (164), the rewind side flexible substrate sensor (166) and the rewind side stamping foil sensor (168) are high-speed and high-resolution optical sensors.