Registers – Records – Laminated
Reexamination Certificate
2000-01-20
2001-03-27
Le, Thien M. (Department: 2876)
Registers
Records
Laminated
C235S492000
Reexamination Certificate
active
06206292
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed to directly printable and/or writable RFID transponders which can be used as labels, tags for transported goods, identification cards and access authorization cards.
BACKGROUND OF THE INVENTION AND PRIOR ART
The use of labels as remotely readable identification tags for baggage items is known. These labels comprise, for example, a flexible substrate on which is formed an antenna having a transponder circuit chip, and adhesive films for joining chip and antenna in the region of the antenna contacts and the chip contacts and also between the transponder, the substrate and a protective sheet. A label of this kind is disclosed in EP-A-595 549.
DE-A-38 07 936 discloses an electronic theft prevention system which operates with a transmitting frequency in the GHz range (approximately 2.5 GHz) in order to allow the dimensions of the passive security element (passive transponder) to be small. The passive security element is combined with the goods label to form a unit. This security system known from DE-A-38 07 936 makes use of a stationary means described in DE-A-40 02 738—for registering and identifying mobile passive radio recording chips, which allows information to be stored in an addressed passive radio recording chip and allows information stored in such a chip to be interrogated at any point in time, all in a controlled manner. The fastening of the passive registration chips to letters, packets, parcels or baggage items is described.
In the case of the known labels or cards with RFID transponders, which have a carrier sheet with circuit chip and antenna disposed thereon, the so-called film transponders are laminated between an upper label material comprising paper or a polymer film and further layers in order to protect chip and antenna against damage. Similar laminate structures are also known for entry cards, travel cards and attachable labels with RFID transponders. These laminates can be printed on the front, and optionally on the reverse as well, using processes typical for the purpose.
The object of the invention is to simplify the construction of labels, tags for transported goods, identification cards, access authorization cards and the like each having an RFID transponder with an antenna and, connected to it, a circuit chip so as to permit their more cost-effective mass production.
SUMMARY OF THE INVENTION
This object is achieved by means of RFID transponders having a printable surface, and comprising (a) a polymer film having two major surfaces opposite to each other as substrate for (b) at least one antenna and a circuit chip electrically connected thereto, both being attached to one of the major surfaces of said polymer film and (c) a printable layer disposed on one surface of said polymer film and (d) an adhesive layer disposed on the opposite major surface of said polymer film and (e) a cover layer adjacent to said adhesive layer to cover the open surface of said adhesive layer and wherein the printable layer comprising particulate pigment and film forming binder to provide the printable surface at the top side of the RFID transponders.
According to another embodiment of the invention the RFID transponders having a printable surface, and comprising (a) a continuous polymer film strip having two major surfaces opposite to each other as substrate for (b) a plurality of RFID transponders, each comprising at least one antenna and a circuit chip electrically connected thereto, both being attached to one of the major surfaces of said polymer film strip and (c) a printable layer disposed on one surface of said polymer film strip and (d) an adhesive layer disposed on the opposite major surface of said polymer film strip and (e) a cover layer adjacent to said adhesive layer to cover the open surface of said adhesive layer and wherein the printable layer comprising particulate pigment and film forming binder to provide the printable surface at the top side of said RFID transponders which are formed at a distance from one another in the running direction of said polymer film strip.
DETAILED DESCRIPTION OF THE INVENTION
The polymer films which are suitable as support or carriers can, for example, be polyester films, polyvinyl chloride films, polyolefin films (poly-propylene, polyethylene), polycarbonate films, polystyrene films, polyamide films or cellulose acetate films. The carrier films have a thickness of preferably from 30 &mgr;m to 820 &mgr;m, with particular preference from 36 &mgr;m to 100 &mgr;m.
The support films can be transparent or opaque and can if desired have a microporous structure. The support films may for their part already be of printable and/or writable configuration. In such a case it is possible, if desired, to omit the application of an additional printable layer.
In order to form flat, especially rectangular, RFID transponders an antenna in one or more turns made from an electrically conductive material is applied to one or both sides of a support or carrier film made of plastic. The antenna is formed on the dielectric polymer carrier film by means of customary measures. The antenna has antenna contacts which are preferably arranged on the carrier film in such a way as to be delimited by the antenna coil. The antenna turn(s) has (have) a thickness of from 10 &mgr;m to 50 &mgr;m.
The circuit chip, which is likewise fastened to the carrier film, has first and second electrical chip contacts in front of an inner zone of the chip surface, and the electrical connection of the chip to the antenna is established preferably by means of electrically conductive adhesive which is arranged between the antenna contacts and the chip contacts.
Preferably, antenna and circuit chip are arranged on the same side of the polymer film. This is especially preferred when the carrier film used is a polymer film which is for its part of directly printable design. In principle, however, antenna and circuit chip and, if desired, capacitors can also be arranged on opposite surfaces of the carrier film. In this arrangement the electrical connection is made through the polymer film.
The printable and/or writable layer of the invention is preferably arranged on that surface of the polymer film on which there is no chip. The printable/writable layer can be opaque or else semitransparent.
The printable layer contains finely divided pigments, examples being inorganic pigments or fillers, such as kaolin, calcium carbonate, silica, silicates, alumina, aluminum hydroxide, zinc oxide, barium sulfate, talc or mixtures thereof. It is also possible, however, to use the organic polymer pigments known for paper coatings, alone or in combination with inorganic pigments, for the printable layer.
Examples of suitable film-forming binders for forming the layer and fastening the pigments to the carrier film are polyvinyl alcohol, polyvinyl-pyrrolidone, casein, starch, starch derivatives, styrene-maleic anhydride copolymers, and also the customary polymer latices known for paper coatings, such as styrene-butadiene copolymers, styrene-acrylic acid copolymers, and acrylic latices. In principle it is also possible to use mixtures of soluble binders with one another or latices with soluble binders or mixtures of latices.
It is also possible to use solvent-based coating compositions, with nitrocellulose as binder, for example, for forming the printable layer.
The ratio of pigment to binder is chosen so as to ensure adequate adhesion of the printable layer to the polymer film: however, the layer still has sufficient porosity to be readily printable.
In general, from 5 to 30 parts by weight, preferably up to 20 parts by weight of binder per 100 parts by weight of pigment are sufficient to form a printable and/or writable layer of sufficient strength.
The printable layer may further include customary auxiliaries, such as dispersants, defoamers, crosslinking agents, adhesion promoters, thickeners, dyes and UV stabilisers.
The printable layer preferably has an applied weight (dry) of from 5 g/m
2
to 30 g/m
2
, preferably from 7 g/m
2
to 20 g/m
2
.
In one em
Liebler Ralf
Robertz Bernd
Doepken Keevican & Weiss
Harmuth, Esq. Raymond J.
Le Thien M.
Sihl GmbH
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