Security marking label, particularly for motor vehicle

The invention relates to a security marking label for a transparent support such as the windshield of a motor vehicle. The label comprises information specific to the marked support. The label is comprised of a complex formed of two superimposed elements between which is interleaved a marking element, at least one of said elements having a layer appropriate to provide for the binding of the transparent support and at least one of said elements comprising a diffraction network.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention pertains to highly secure marking labels for the
 visible or partially coded identification of a glass panel such as an
 automobile windshield. The information must be definitively affixed to the
 interior of the passenger compartment, on the glass panel, and be visible
 from the exterior. This can be the case for documents such as, for
 example, automobile registration stickers, proof of insurance or tax
 stickers. These documents bear general information supplemented by
 specific information pertaining to the vehicle or its owner.
 2. Description of Related Art
 Various types of such labels are already known in the state of the art. One
 can cite French patent FR 2716559 pertaining to a plaque designed for
 marking, certification and/or control operations which can be applied on a
 transparent support surface. It comprises a plastic film support, an
 imprint on its first surface and a first transparent adhesive layer
 applied on this imprint, as well as a first removable protective coating.
 A second adhesive layer is applied to the second support surface and is
 covered by a second removable protective coating. A control coupon is
 applied on the second coating by means of a third adhesive layer. The
 support and the coupon bear mutually corresponding information.
 Nevertheless, the devices according to the state of the art do not provide
 a high level of security against fraud, and it is relatively easy to peel
 off an original document and to modify the personalization information in
 an undetectable manner.
 SUMMARY OF THE INVENTION
 The object of the present invention is to resolve this drawback by
 proposing a highly secure marking label that limits the possibilities of
 fraud stemming from either forgery or reuse of an original label.
 For this purpose, the invention pertains more specifically to a highly
 secure marking label to be affixed on a transparent support such as a
 vehicle windshield and bearing information specific to the marked support,
 characterized in that it is constituted by a complex formed by two
 superimposed elements, between which is interposed a marking element, with
 at least one of said elements exhibiting a layer that assures bonding onto
 the transparent support and with at least one of said elements bearing a
 diffraction grating.
 Advantageously, the first element is formed by a transparent plastic film
 bearing on one of its surfaces an adhesive to enable bonding of said
 element onto the transparent support to be marked and exhibiting on the
 other surface an easily broken layer and a transparent lacquer layer
 stamped with a holographic image.
 Said transparent lacquer layer is preferably stamped with a holographic
 image that covers the entire surface of said element.
 According to a preferred mode of implementation, the second element is
 appreciably larger than the first element.
 The second element is preferably constituted by a transparent film coated
 with an easily broken layer and a layer of metallized lacquer stamped with
 a holographic image and by an adhesive capable of bonding said element
 onto the transparent support to be marked and onto the element.
 According to a variant, the second element in addition bears an adhesive
 layer for the gluing on of a protective film.
 According to a first mode of implementation, the personalization
 information is printed on the stamped surface of the first element.
 According to a second mode of implementation, the personalization
 information is printed on the marking element.
 According to a third mode of implementation, some of the personalization
 information is masked by a spectrally selective transmission layer.
 According to a specific mode of realization, the first element comprises a
 layer of lacquer that is opaque in the visible and transparent in a given
 wavelength band such that the coded information is hidden from
 unauthorized persons.

DETAILED DESCRIPTION
 FIG. 1 shows a front view of a label according to the invention. It
 exhibits various types of information. Certain information (1) is
 imprinted in an invariable and identical manner for all of the labels.
 Other information (2) is formed by diffraction grids forming a holographic
 security image. Other information (14) is specific to the marked support
 and is variable from one label to another. Finally, certain information
 (15) is specific to the marked support and variable from one label to
 another and is protected by a transparent diffraction grid.
 The second element (12) of the label exhibits a surface larger than that of
 the first element (13) and protrudes laterally.
 The second element (12) can exhibit breakage starting points to make the
 label easily broken and to make fraud more difficult.
 FIGS. 2 and 3 show views along section AA' at an enlarged scale.
 The label is glued onto a glass surface (16) by an adhesive layer (6)
 provided on one of the surfaces of a support film (3), for example, a
 transparent polyester film. The other surface of the support film (3) can
 be covered by an easily broken layer (4) and by a transparent lacquer
 layer (5) stamped with a holographic image on its entire surface. Any
 attempt to separate this layer will cause the total destruction of the
 image.
 The layer (5) can also be implemented in the form of a metallized or
 partially metallized stamping lacquer. This layer creates one or more
 windows through which the imprints (1) or (14) can be seen.
 In addition, the label has an optional partial layer (7) of lacquer which
 is opaque in the visible and transparent in a given wavelength band, for
 example, in the infrared. This layer (7) makes it possible to mask certain
 coded information (15), the access to which is limited to people
 authorized to perform monitoring operations by means of a specific device,
 for example, an infrared light source.
 This layer (7) is affixed by offset printing at the time of mass production
 of the label (before personalization).
 The second element (12) guarantees that the marking element can not be
 moved. Any attempt to peel off the marking label (fraudulent reuse of an
 original label) causes the tearing of the delimited zone due to the
 surface difference of the two elements. Any attempt to separate the two
 elements constituting the marking label (tampering) causes the destruction
 of the surface common to the two elements. The second element (12)
 comprises:
 a stamped metallized lacquer layer (10)
 an easily broken layer (9)
 a transparent polyester film (20) of the same type as the film (3).
 The second element (12) is glued onto the first element by means of a glue
 layer (11) with the same characteristics as the glue (6) of the first
 element.
 The second element can also be covered on the exterior by a thick, opaque
 film (8), with this film (8) being advantageously an adhesive protective
 film.
 The labels can be manufactured as follows:
 A first labeling machine places the first element (13) on a siliconized
 film and then personalizes it with an ink-jet or thermal printer. The
 personalized and possibly partially coded information is printed on the
 stamped surface of the transparent laquer layer (5) or possibly on the
 optional partial layer (7). A second labeling machine then places the
 second larger element (12) on the first element.
 The use of figure reference labels in the claims is intended to identify
 one or more possible embodiments of the claimed subject matter in order to
 facilitate the interpretation of the claims. Such labeling is not to be
 construed as necessarily limiting the scope of those claims to the
 embodiments shown in the corresponding figures.