A method of forming an image, and a product having an image formed thereon

Abstract: A security card is provided in which an ink region 6 bearing image or textural data is printed onto a substrate 4. A reflective portion 8 is also provided on the substrate 4. A plastics protective layer 7 is deposited over the ink 6 and reflective element 8. Portions 10 of the protective layer 7 are overworked in order to change their appearance. Those portions overlying the reflective element 8 exhibit enhanced visibility.

Description: The present invention relates to a method of forming an image, and to a product having an image formed thereon. In particular, this invention provides an enhanced security image. WO96/30215 describes a method of forming an image on a surface of a card, and in particular the formation of a security card. In general terms, a plastics card is provided on to which an image and other data or markers is printed for example using a dye sublimation or dye diffusion printing process. Once printed, the image on the card is protected by laying down a thin transparent plastic coating. The plastic coating (hereinafter called "overcoat") is deposited by thermal transfer printing. Security images can also be formed in the overcoat by overheating portions of it, thereby changing the optical properties over the overcoat. In general, the overheated portions of the film take on a less glossy (i.e. matt or satin), appearance. Thus additional images confirming the authenticity of the card can be formed in the transparent layer, with the printed portion of the card being visible therethrough. The security images can be easily seen when the card is illuminated by a unidirectional light source, but are less clear when viewed in diffuse light. United States patent US 4,501,439 describes a security blank that includes a substrate that may have a metallized surface. A thermoplastic layer overlies the substrate into which an authenticity feature in the form of an optical microstructure is embossed. A protective transparent layer overlies the authenticity feature. According to a first aspect of the present invention, there is provided a method of forming a security card, the method being according to claim 1. It is thus possible to provide an improved security card. The applicant has discovered that the security markings become much more visible, even in diffuse light, when printed over a reflective region. Advantageously the reflective region comprises a reflective film, such as a metallic film, or a film exhibiting mirror like reflection properties. The metal film may be printed on to the substrate. Thus a metal film may be provided on blank card stock at the time of manufacture of security cards. Alternatively, the reflective film may be printed onto the card as part of the card printing process. Thus, for example, the metal film may be provided on a carrier film and be brought into contact with the substrate at a printing station in order to transfer the metal film to the substrate. The layer of plastics film is provided on a carrier film. The carrier film is brought into contact with the substrate at a printer having a plurality of heater elements. The heater elements are energised in order to thermally transfer the plastics material from the carrier film to the substrate. The heater elements may be energised at a plurality of energy levels in order to vary the thickness of the plastics film transferred. The varying thickness thereby resulting in a variable appearance of the film. The security image may be repeatedly printed across the card in a repeat and step like manner. However at least one of the images overlies the reflective region. Advantageously the print instructions for the security image are stored in a memory device. The memory device may, for example, be implemented in the form of a removable memory card, a dongle, a smart card or other equivalent removable memory element. The security image may be held in an encrypted form and local processing may also be provided such that the encrypted image cannot be accessed without a suitable key. The key may, for example, be available to authorise users on a time limited fashion such that once the key expires the security image can no longer be printed. Replacement keys may be obtained via a telecommunications network, for example over the internet, or by distribution of suitably encoded disks or by passwords. Alternatively the printer itself may act as the key to read the data from the memory element. The printer may have a data processor arranged such that the printer negotiates with the memory element to obtain the security image therefrom. The security image may be in an encrypted form. The encrypted form may differ every time the image is read from the memory device. The data processor in the printer is arranged to decrypt the image. According to a second aspect of the present invention there is provided a security card obtainable by the method according to claim 1. It is thus possible to provide a security card comprising a plastics substrate bearing on at least one portion thereof a reflective element, and a plastics layer deposited over the substrate and the reflective element, the optical properties of the plastics layer being altered in at least the region overlying the reflective element in order to form a visible marking therein. The substrate is thermally printed with identification details, such as words, pictures or other indicia. The printing may be performed by dye sublimation printing. Following the printing step, the protective layer is then deposited on the card, preferably with the simultaneous formation of security images in the protective layer. The protective layer is applied to the card by thermal transfer. The present invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a thermal array print head as used according to the present invention; Figure 2 illustrates how the print head of Figure 1 prints an image by depositing pigment on a receiver surface; Figure 3 is a cross section of a printed receiver surface of Figure 2 with a protective plastics film coating applied to it and incorporating a texture image therein; Figure 4 is a plan view of a security card constituting an embodiment of the present invention; and Figure 5 schematically illustrates a printer for printing a card according to the present invention. As shown in Figures 1 and 2, a thermal print head 1 is in intimate contact with a carrier film 2 on which a pigment 3 on the surface thereof is pressed against a receiver layer 4. The receiver layer acts as a substrate. The carrier film 2 and the receiver layer 4 are moved together relative to the print head 1. In use, heater elements 5 aligned along the print head are selectively energised by electrical pulses to transfer dots or pixels 6 of pigment to the receiver layer 4 in successive lateral rows across the width of the receiver layer. The receiver layer is provided, at least in part, with one or more reflective areas formed by bonding or otherwise depositing a shiny, and preferably metallic, film to the surface of the receiver layer 4. The reflective region is designated 8 in Figures 3 and 4. The reflective layer 8 may be deposited in a printing step prior to the printing of the pixels of ink, or may be provided as part of the receiver layer, for example during its manufacture. During a subsequent plastics coating process, which could involve the same print head 1 or a similar print head, a coating of clear plastics material 7 is transferred onto the receiver layer 4, thereby overlaying the pigment layer 6 and the reflective layer 8. The clear plastics material is be carried on a carrier film which passes beneath the print head with the receiver layer 4 in a similar manner to that described with reference to Figure 2. Again the heater elements of the print head are selectively energised to transfer pixels or dots of the plastics material 7 to the receiver layer 4 in a continuous manner so that the whole of the pigment layer 6 and the reflective element 8 are coated. The heater elements 5 may be selectively energised so as to transfer varying thicknesses of the plastics layer to the receiver layer 4. However, in a preferred embodiment, the heater elements are energised so as to transfer the whole thickness of the carrier film to the receiver layer 4, with selected areas 10 being heated to a greater amount. The additional heating overworks the clear plastics layer and modifies its shiny upper surface thereby creating regions 10 which are not shiny and which have a matt or satin like appearance. Thus a uniformly thick protective layer bearing an image can be deposited onto to receiver layer and images printed thereon. The applicant has found that, unexpectedly, those images printed over the reflective element 8 are clearly visible even in diffuse light and this enhances the usefulness and visibility of the security image. Figure 4 schematically illustrates a security card constituting an embodiment of the present invention. In plan view, various images 12, 14 and 16 are formed in the plastics layer 7. The image 12 overlying the reflective element 8 is clearly visible, whereas the images 14 and 16 not overlying the reflective layer 8 are more faint. The image 16 overlies a printed area 18 with a text or other image formed in the area 18 being visible through the security image 16. Figure 5 illustrates a printer for printing identity or other secure cards. The instructions for encoding the security image may be encoded within a removable encryption processor and memory element 20, which may, for example, be a compact flash package removable from or introducable into a suitable reader 22 in a card or other printer 24. It is thus possible to provide an improved security printing method and an improved security card. In testing, blank cards with the reflective patch 8 preformed thereon were obtained from Bristol Business Cards of Bristol, England.

Claims: A method of forming a security card, the method comprising: providing a substrate (4) having at least one reflective region (8) thereon; thermally depositing identification details onto the substrate (4); and providing a layer of plastic material (7) over the substrate (4), heating at least one selected region (10) of the plastics material (7) to a greater degree than other areas, the or each selected region (10) overlying a corresponding one of the or each reflective region (8), so as to vary the surface appearance of the or each selected region of the plastics material (7), the layer of plastic material being provided on a carrier film (2) the heating being by means of a plurality of heater elements (5) are provided on a thermal print head (1), the heater elements (5) are energised when the carrier film is in contact with the substrate to transfer the plastic material (7) to the substrate (4).. A method as claimed in claim 1, characterised in that the at least one reflective region (8) comprises a metal film. A method as claimed in claim 2, characterised in that the metal film (8) is printed onto the substrate. A method as claimed in claim 3, characterised in that the metal film (8) is provided on a carrier film and is brought into contact with the substrate at a printing station and transferred to the substrate. A method as claimed in claim 1, characterised in that the heating elements (5) are energised to deposit a continuous layer of the plastic material (7) over the whole of the area to be covered such that the plastic material serves as a protective coating. A method as claimed in any preceding claim, characterised in that the or each overheated region (10) has a less glossy appearance than non-overheated regions of the plastics material (7). A method as claimed in any one of the preceding claims, characterised in that the image (12, 14, 16) is printed over the substrate in a repeating pattern. A method as claimed in any one of the preceding claims, characterised in that the layer of plastic material is deposited on the substrate (4) during a printing process, and in which the image (12, 14, 16) to be formed in the plastic film is held in a memory device (20) readable by one of the printer and a data processor controlling the printer. A method as claimed in claim 8, characterised in that the memory device (20) is a removable device. A method as claimed in claim 8 or 9, characterised in that the image is held in an encrypted form. A security card obtainable by the method according to any of the claims 1-10. A security card as claimed in claim 11, characterised in that the plastic layer (7) is deposited as a substantially uniform layer.

Inventors: COLES RAYMOND W, COLES, RAYMOND W.
Applicants: ULTRA ELECTRONICS LTD, ULTRA ELECTRONICS LIMITED
Application year: 2001
Main classification: B41M5
IPC codes: B41M5, B42D15, G06K19, B41M3