The instant invention relates to apparatus used in the production of identification cards, and more particularly relates to apparatus for applying a protective, transparent laminate sheet to the surface of a plastic card substrate to protect identification information printed on the surface of the plastic card and to further provide resistance to tampering of the information.
It is well known that laminated cards are widely used for identification cards, licenses, etc. In the past, identification cards were typically formed by printing identifying information on a paper based substrate and bonding the paper based substrate between two thick transparent protective sheets. The transparent sheets protected the printed information from the wear and tear of handling, as well as from tampering. More recently, significant use has been made of durable, polymer based materials for card substrates wherein the printed information is printed directly onto the card substrate. From a security and durability standpoint it is necessary to protect the printed information with a transparent overlay or laminate much like the earlier paper based identification cards. However, the new security laminates are much thinner because the plastic card substrates provides all of the necessary rigidity. As with their paper ancestors, the transparent laminate sheets can be provided with water-marks or security features to insure the security and authenticity of the card.
Apparatus for applying a laminate sheet to the surface of a card substrate has heretofore been known in the art. In this regard, the U.S. Pat. No. 5,783,024 to Forkert represents the closest prior art to the subject invention of which the applicant is aware. Forkert discloses a single-sided laminating apparatus effective for applying a sheet of laminate film onto a single side of a card substrate. The apparatus comprises a lamina supply roll capable of holding a supply of lamina from which successive sheets of lamina can be cut with a cutting device. A cut sheet of laminate is aligned with the card and passed under a heated roller to bond the laminate sheet the card substrate. While the Forkert apparatus is effective for its intended purpose, it has several shortcomings which make its practical implementation and use difficult. The first shortcoming is that the apparatus is effective only for a single-sided lamination during each pass of the substrate through the apparatus. While this does immediately appear to be a shortcoming, there are several mechanical, chemical and practical issues to consider. A first issue is that cards are often printed on both sides, and therefore it is desirable to place a protective laminate film on both sides of the card. This can only be achieved in the Forkert apparatus by running the card through the apparatus two separate times. In high volume applications, such as the issuance of driver""s licenses, where time is an issue, the need to laminate the card twice is an obvious time constraint to the quick and efficient production of the cards. A second issue is that the laminate film tends to shrink upon the application of heat, thus causing the card to curl upwardly on the side with the laminate film overlay. The amount of curl is dependent upon the physical properties of the laminate which can vary from roll to roll even within the same batch of material. Forkert took this factor into consideration and provided a mechanical card straightener to provide a reverse bend in the card. However, the card straightener adds to the complexity of the device. Furthermore, because of variations in the laminate sheet, the amount of curl is not always the same, and thus the straightener is not always effective for applying the correct amount of reverse bend. Another shortcoming of the Forkert device is the nature of the lamina film transfer mechanisms. The lamina used to laminate the subject cards is very thin and difficult to handle in sheet form. Forkert utilizes sets of nip rollers to successively push the cut laminate sheets toward the convergence zone. Wire guides maintain the laminate on a lamina supply path. In practice, it is difficult to push this type of laminate beyond a set of nip rollers when there is any type of guide since the laminate material naturally tends to adhere to the guide members.
The instant invention provides an improved card laminating apparatus which is effective for simultaneously applying laminate sheets to both upper and lower sides of a card substrate and for bonding the laminate sheets to the card substrate using a pair of symmetrically aligned heated rollers. Symmetric heating of both sides of the card reduces lamination to a single step, reduces substrate curling due to uneven heating, and eliminates the need for a mechanical card straightener. The improved apparatus further provides a unique drive assembly for pulling the laminate through the apparatus to insure proper laminate registration and tracking and a unique transfer assembly for applying the laminate sheets to both sides of the card.
More specifically, the apparatus includes two identical laminating assemblies that are symmetrically mounted in mirror image relation on opposing sides of a substrate supply path along which the card substrate travels. Individual sheets of laminate are cut from webs of lamina and transferred onto the card substrate at a convergence zone where the sheets of laminate are brought together in overlying registration with the substrate. Each of the laminating assemblies includes a web of lamina mounted in a cassette, a cutter capable of cutting sheets of laminate from the web, and nip rollers disposed between the web and the cutter. The idle roller of the pair of nip rollers is formed as part of the cassette to ease loading of the web of lamina into the apparatus. When the cassette is mounted on the frame, the idle roller engages with the drive roller to form the nip. The nip advances the web of lamina in an upstream direction through the cutter. Each laminating assembly further includes a transfer roller and laminate guide disposed between the cutter and the convergence zone. As the lamina is advanced through the cutter, the leading edge of the web is captured between the outer surface of the transfer roller and a laminate guide. The laminate guide member and the outer surface of the transfer roller cooperate to form an arcuate laminate supply path with the transfer roller pulling the leading edge of the web of lamina in an upstream direction from the cutter to the convergence zone. A transfer member disposed in the convergence zone strips the leading edge of the sheet of laminate from the outer surface of the transfer roller and transfers the sheet of laminate into overlying registration with the substrate as the substrate passes through the convergence zone. A heater is disposed downstream of the convergence zone.
Each of the laminating assemblies further includes a lamina sensor for sensing the leading edge of the web of lamina and a unique drive assembly operative for integrated rotation of the nip rollers and the transfer roller. The drive assembly comprises a drive motor, and a gear train interconnecting the drive motor with the transfer roller and the drive roller of the nip rollers. The gear train is constructed and arranged to rotate the outer surface of the transfer roller at a greater speed than the outer surface of the drive roller of the nip rollers such that the transfer roller pulls the web along the lamina supply path faster than the drive roller pushes the web. The drive roller of the nip rollers includes a one-way clutch which allows free rotation of the drive roller only in the downstream direction. This arrangement prevents the nip rollers from advancing the web too quickly, allows the transfer roller to pull the web through the lamina supply path rather than pushing the lamina, and also provides a gap between the trailing edge of the cut sheet of laminate and the leading edge of the web. The gap allows the lamina sensors to more accurately detect the leading edge of the web and to stop rotation of the transfer roller at the proper time.
The substrate is automatically transported along the substrate supply path by successive pairs of nip rollers which pass the substrate between the respective transfer members of the laminating assemblies and between the heaters wherein the laminate sheets are bonded to the substrate.
During operation of the apparatus, a web of lamina is advanced downstream by the nip rollers where it is captured by the transfer roller. As described above, the transfer roller is driven at a greater speed than the nip rollers wherein the transfer roller now pulls the web of lamina faster than the nip rollers advance the web. The lamina sensor is positioned on the circumference of the transfer roller at a position wherein the distance between the sensor and the cutter equals the required length of the sheet of the laminate. When the sensor senses the leading edge of the lamina, rotation of the transfer roller and nip rollers is stopped, and the cutter actuated to sever a sheet of laminate from the web. The operation is identical for both laminating assemblies. When both sheets of laminate are ready for transfer, the substrate is inserted into the substrate transport and advanced along the substrate supply path. When a substrate sensor detects the leading edge of the substrate, the drive assembly is energized and rotation of the transfer roller and nip rollers resume. The timing of advancement of the substrate and rotation of the transfer rollers is such that the leading edges of the laminate reach a convergence point at the same time as the leading edge of the substrate. As the transfer rollers continue to rotate, the stripper fingers on the transfer members strip the laminate sheets from the surface of the transfer rollers and force the laminate sheets into overlying relation with the substrate. Since the nip rollers are driven by the same motor as the transfer roller, the nip rollers are also advancing the web until the leading edge of the web is captured by the input portion of transfer roller. The drive assembly continues to operate until the lamina sensor detects the leading edge of the lamina. Thereafter, the drive motor is shut off and the cutter severs the web to form a new sheet of laminate. As indicated above, since the transfer roller advances faster than the nip rollers advance the web, a small gap if formed between the trailing edge of the sheet of laminate being transferred and the new web of lamina being fed. As the substrate exits the convergence zone, the leading edge of the substrate is immediately captured between two heated nip rollers to heat bond the laminate sheets to the substrate. The heated nip rollers include a non-rotating heated core and a rotating outer surface. The heaters are symmetrically positioned in mirror image relation to form a nip.
Accordingly, among the objects of the instant invention are: the provision of a two-sided card laminating apparatus; the provision of a two-sided card laminating apparatus that simultaneously laminates both sides of a substrate; the provision of such a laminating apparatus which provides even heating of the laminate sheets to reduce curling of the substrate; the provision of such a card laminating apparatus wherein two mirror image laminating assemblies are symmetrically mounted in mirror image relation on opposing sides of a substrate supply path; the provision of such an apparatus wherein the webs of lamina are mounted in cassettes which form part of the advancement nip; the provision of such a card laminating apparatus wherein the laminate sheets are applied to the substrate using transfer rollers; and the provision of such an apparatus wherein the transfer rollers cooperate with a laminate guides to capture the sheets of laminate in a fixed lamina supply path.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.