Printed matter – Having revealable concealed information – fraud preventer or... – Utilizing electromagnetic radiation
Reexamination Certificate
1999-06-28
2001-01-30
Fridie, Jr., Willmon (Department: 3722)
Printed matter
Having revealable concealed information, fraud preventer or...
Utilizing electromagnetic radiation
C283S109000, C283S111000
Reexamination Certificate
active
06179338
ABSTRACT:
This invention relates to a multilayer data carrier bearing general printed data, having at least one opaque layer and at least one transparent layer containing additives which are absorbent for a laser beam, whereby information is incorporated in the transparent layer by means of a laser beam in the form of local changes in the optical properties of the layer.
Data carriers in the form of identity cards, credit cards, bank cards, cash cards and the like are used to an increasing extent in a great variety of services sectors, for example in cashless money transfer and in the in-company area. On the one hand they are typical mass-produced articles due to their widespread use; their manufacture, i.e production of the card structure and incorporation of the card-specific user data, must be simple and cost-effective. On the other hand the cards must be designed so as to be protected against forgery and falsification to the greatest possible degree. The many types of identity cards already on the market and still in the developmental stage reflect the efforts of the relevant industry to optimize these two contrary conditions.
DE-C 31 51 407 discloses for example an identity card wherein a plastic layer is provided in the card as a recording medium which appears completely transparent when viewed normally but absorbs the light of a laser beam so strongly that the laser beam causes blackening in the film. Pictures or data can thus be incorporated in the basically transparent layers in tamper-resistant fashion in the last processing step. The film suitable for laser inscription can be used either as a cover layer over the so-called card inlay or together with other transparent cover films which also appear transparent for the laser pencil.
Although the identity card presented in DE-C 31 51 407 already has a high measure of resistance to forgery there are still efforts to broaden the possibilities of designing the card with respect to its visual impression and to impede falsification and total forgery of cards further by introducing additional authenticity features that are reproducible only with high technical effort.
It is thus proposed e.g. in EP-C 0 219 012 to incorporate a transparent layer suitable for laser inscription in the identity card and to cover this layer by a cover layer that is transparent both in the visual range and for the laser pencil. This layer is provided in a partial area with a lenticular screen. The layer suitable for laser inscription is inscribed by a laser through this lenticular screen. The lenticular screen focuses the laser in the layer suitable for laser inscription so that rod-shaped blackenings arise in this laver that penetrate the total thickness of the layer. If the transparent layer suitable for laser inscription is provided with data by the laser beam through the lenticular screen at various angles in this way, images arise in this layer that are fundamentally visible only at this angle. When the thus inscribed card is rotated about the particular card axis one can observe a so-called “tilt effect” since the laser-inscribed data are only visible at times during rotation.
Finally it is known from EP 0 219 011 to provide identity cards with several transparent films suitable for laser inscription. These films are selected so that it is possible to incorporate data by means of a laser beam in several lavers simultaneously or only in one individual layer selectively, whereby these pieces of information can also be separated from one other by a transparent intermediate area. By suitably selecting the films it is e.g. also possible to incorporate an uninterrupted image in a film whereas the same image is simultaneously incorporated in the other film with an interruption.
The above publications have in common that information is inscribed by means of a laser beam in one or more transparent films which are suitable for laser inscription, i.e. accordingly sensitized.
The thickness of the layer suitable for laser inscription is given by the thickness of the sensitized film. In the abovementioned cards with a tilt or parallax image it is advantageous if the laser inscription is designed as thinly as possible to avoid overlapping of the individual tilt or parallax images at certain viewing angles. During production of cards it is no longer possible to handle the film with a thickness of less than 50 microns, so that this also determines the minimum thickness of inscription. This does not permit production of tilt or parallax images without disturbing overlapping of the individual partial pictures at various viewing angles. Furthermore the minimum thickness of laser inscription limits the obtainable picture definition in all cards to be inscribed.
The film is sensitized for laser radiation by special additives which are incorporated in the basically transparent film in a concentration that impairs the transparency of the film as little as possible but provides sufficient absorption centers for the laser energy where discoloration of the film material or the material transformation can begin.
The invention has an object to provide a compund film for a multilayer identity card with laser inscription wherein the inscription has improved sharpness and resolution.
The basic idea of the invention is to provide a layer containing at least one additive in the card structure of a multilayer data carrier, this layer being thin in relation to the other layers of the data carrier. This layer can be incorporated at virtually any place in the layer structure. The layer as such is nonself-supporting, i.e. it is not processible as a separate layer but only together with a thicker carrier layer which is laminated with further layers into a multilayer data carrier. The small thickness of the layer permits laser inscription which is limited to an extremely small volume area relative to the card thickness.
The advantage obtainable with the invention is in particular that the use of the inventive layer makes it possible to obtain a sharply delimited, clearly contoured laser inscription of the data carrier. In a card with tilt or parallax images, for example, the individual images can be distinguished from one other much better at different viewing angles so that their optical effect is improved. The sensitizing of plastics is known and described for example in EP-C 0 232 502 and EP-C 0 190 997.
In a preferred embodiment the thin, nonself-supporting layer is disposed in the interior of the card so that it is protected from environmental influences or influences resulting from daily use of the data carrier. It has proved to be particularly advantageous to cover the thin, nonself-supporting layer with a transparent layer that can also bear the general printed data on its inner side.
In a further special embodiment the inventive layer consists of a sensitized layer of lacquer, which permits further advantages to be obtained. Much higher flexibility is thus given in the production of the card since the layers of lacquer can be produced separately from the film production and incorporated in the card structure in almost any step of the card production. Since the composition of the layers of lacquer and thus also their laser sensitization properties are variable at short notice one can also consider modifications of the layer of lacquer at short notice during card production independently of the stock keeping of the films. Along with conventional all-over application of the layers of lacquer one can now also sensitize partial areas of the card with layers of lacquer, whereby these layers can also be applied in the form of an image or pattern. The limits to the possibilities are determined only by the limits of printing technology. Several layers of lacquer can thus also be disposed one above the other or different lacquers combined with one other so that e.g. differently sensitized surface areas are realizable in different card areas. Since the layers of lacquer are applicable in almost any layer thickness only accordingly smaller volume areas of the cards are “discolored” during lase
Bergmann Matthias
Henkenschuh Horst
Krusche Reinhard
Riedl Joseph
Andrus Sceales Starke & Sawall LLP
Fridie Jr. Willmon
GAO Gesellschaft f{umlaut over (u)}r Automation und Organisation
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