Patent Publication Number: US-2019171921-A1

Title: Flexible fabric tags using apertures in a substrate

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     The present invention claims priority from and the benefit of U.S. provisional patent application No. 62/593,609 filed on Dec. 1, 2017, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     The present invention relates generally to a flexible fabric tag. The tag comprises a conductor embedded into a flexible material that forms an antenna for a radio-frequency identification (“RFID”) tag. The present subject matter is especially suitable for garments and other apparel items. Accordingly, the present specification makes specific reference thereto. However, it is to be appreciated that aspects of the present inventive subject matter are also equally amenable to other like applications. 
     Radio-frequency identification (“RFID”) is the use of electromagnetic energy (“EM energy”) to stimulate a responsive device (known as an RFID “tag” or transponder) to identify itself and in some cases, provide additionally stored data. RFID tags typically include a semiconductor device commonly called the “chip” on which are formed a memory and operating circuitry, which is connected to an antenna. Typically, RFID tags act as transponders, providing information stored in the chip memory in response to a radio frequency (“RF”) interrogation signal received from a reader, also referred to as an interrogator. In the case of passive RFID devices, the energy of the interrogation signal also provides the necessary energy to operate the RFID device. 
     RFID tags may be incorporated into or attached to articles to be tracked. In some cases, the tag may be attached to the outside of an article with adhesive, tape, or other means and in other cases, the tag may be inserted within the article, such as being included in the packaging, located within the container of the article, or sewn into a garment. The RFID tags are manufactured with a unique identification number which is typically a simple serial number of a few bytes with a check digit attached. This identification number is incorporated into the tag during manufacture. The user cannot alter this serial/identification number and manufacturers guarantee that each serial number is used only once. Such read-only RFID tags typically are permanently attached to an article to be tracked and, once attached, the serial number of the tag is associated with its host article in a computer data base. 
     However, these sewn in RFID tags can be uncomfortable to the user as the tags tend to create uncomfortable ridges. Further, the sewn in RFID tags do not allow adequate marking surfaces and/or the printable surface is not flat and tends to be hard to read. 
     The present invention discloses a flexible fabric tag that comprises a conductor embedded into a flexible material to form at least one channel. The embedded conductor forms an antenna for an RFID tag. The channel allows the conductor to be buried into the flexible material to prevent uncomfortable ridges and also creates a flat printable surface. 
     SUMMARY 
     The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed innovation. This summary is not an extensive overview, and it is not intended to identify key/critical elements or to delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later. 
     The subject matter disclosed and claimed herein, in one aspect thereof, comprises a flexible fabric radio-frequency identification (RFID) tag device that comprises a conductor embedded into a flexible material to form a channel. The channel does not extend through the total depth of the flexible material. The conductor placed in the channel forms an antenna for an RFID tag when coupled to an RFID chip. 
     In a preferred embodiment, the conductor is a wire or conductive ink that is embedded in the channel. Further, a second layer can be over-laminated on top of the channel. This layer can be used for multiple purposes, such as retaining the conductor, sealing the conductor, and/or presenting a smooth printable surface. Further, in an alternative embodiment, the conductor comprises a wire with an external coating. The coating has an initial state wherein the wire is dry and has a low adhesion and a second state wherein the coating becomes an adhesive and the wire becomes permanently cured at this state. 
     To the accomplishment of the foregoing and related ends, certain illustrative aspects of the disclosed innovation are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles disclosed herein can be employed and is intended to include all such aspects and their equivalents. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a top perspective view of the channel formed in the flexible material in accordance with the disclosed architecture. 
         FIG. 1B  illustrates a top view of an alternative channel formed in the flexible material in accordance with the disclosed architecture. 
         FIG. 2  illustrates a top perspective view of the channel filled with a wire in accordance with the disclosed architecture. 
         FIG. 3  illustrates a top perspective view of the channel filled with a conductive ink in accordance with the disclosed architecture. 
         FIG. 4  illustrates a top perspective view of the channel filled with a rectangular cross-section conductor in accordance with the disclosed architecture. 
         FIG. 5  illustrates a top perspective view of the flexible material being comprised of two layers in accordance with the disclosed architecture. 
         FIG. 6A ,  FIG. 6B , and  FIG. 6C  illustrate a top perspective view of the flexible material being cut and then bent to incorporate a conductor in accordance with the disclosed architecture. 
         FIG. 7  illustrates a top perspective view of the channel with an over-laminated layer on top in accordance with the disclosed architecture. 
         FIG. 8  illustrates a top perspective view of a wire with an additional coating on the outside in accordance with the disclosed architecture. 
         FIG. 9A  illustrates a top perspective view of a wire being guided into the channel by a dispensing head in accordance with the disclosed architecture. 
         FIG. 9B  illustrates a top view of a wire positioned in a channel formed in a flexible material in accordance with the disclosed architecture. 
     
    
    
     DETAILED DESCRIPTION 
     The innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding thereof. It may be evident, however, that the innovation can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate a description thereof. 
     The present invention discloses a flexible fabric tag that comprises at least one conductor embedded into a material, such as, but not limited to, a flexible material, to form a channel. In one embodiment of the present invention, a range of circular wire diameters are available for use. For instance, single strand copper wires in the between 0.032 mm and 0.08 mm are common, although thinner and thicker materials can be used. Rectangular conductors in the form of strips will commonly be made of a foil slit or cut into strips. 
     A variety of foil thicknesses are also contemplated by the present invention. Common values for making printed circuit boards are between 0.0175 mm and 0.035 mm. One factor in the choice of conductor thickness in the present invention, is skin depth, and expression of how the current flows in the surface layers of the conductor. Generally, it may be considered that a conductor of five times skin depth is adequate for a frequency of 915 MHz. For copper wire the skin depth is 0.00215 mm, so approximately a copper wire with a diameter of greater than  ˜ 0.012 mm may present a low loss to RF current. The wire/strip preferably fits inside the channel. In one embodiment, the channel is created with a laser. Although laser beam width is a function of the equipment used, a value of between 50 um and 100 um is common, and compatible with the wire diameters mentioned previously. The channel does not extend through the total depth of the flexible material. The conductor placed in the channel forms an antenna for an RFID tag when coupled to an RFID chip via direct or strap attach. The channel allows the conductor to be buried into the flexible material to prevent uncomfortable ridges and also creates a flat printable surface. 
     Referring initially to the drawings,  FIGS. 1A-B  illustrate a flexible fabric RFID tag device  100  wherein a channel  102  is formed in the flexible material  104 . The material  104  can be any suitable material as is known in the art such as a flexible material like fabric, cloth, canvas, etc. In one embodiment, the channel  102  is shaped to form an antenna  106  but the channel  102  can be any suitable size, shape, and configuration as is known in the art without affecting the overall concept of the invention. One of ordinary skill in the art will appreciate that the shape and size of the channel  102  as shown in  FIG. 1A  is for illustrative purposes only and many other shapes and sizes of the channel  102  are well within the scope of the present disclosure. Additionally, the present invention is not limited to the creation of one channel  102 , but also contemplates that more than one channel may be formed. Although dimensions of the channel  102  (i.e., length, width, and height) are important design parameters for good performance, the channel  102  may be any shape or size that ensures optimal performance. Preferably, the channel should be large enough so that the conductor is fully submerged below the surface with some tolerance, so for a 0.08 mm wire it would be 0.1 mm wide and 0.1 mm deep. 
     The channel  102  or trench typically does not extend through the total depth of the material  104 , and wherein the depth of the channel  102  can depend on a user&#39;s needs and/or wants and the depth is generally large enough, as previously mentioned so that a conductor may be contained within the channel with some tolerance. The channel  102  can be formed by various means such as utilizing a laser to ablate the material to a controlled depth, abrasion, milling, or chemical means using a masking material and solvent for the flexible material, or any other suitable means for forming the channel  102  as is known in the art. 
     Additionally, a conductor is positioned in the channel  102  to form an antenna  106  for an RFID tag when coupled to an RFID chip. As shown in  FIG. 2 , the conductor can be a wire  200 , in one embodiment. The wire  200  can be any suitable material as is known in the art such as copper, copper alloys, aluminum, silver coated materials, etc. In a preferred embodiment, the wire  200  embedded in the channel  102  would be flexible and made of copper. 
     In another embodiment as shown in  FIG. 3 , the conductor can be a conductive ink  300  or other suitable conductive material as is known in the art. The channel  102  can be filled with conductive ink  300  by screening, printing, or any other suitable method as is known in the art. A suitable ink that may be used is DuPont® ME101, a silver ink with good conductivity and the ability to bond to polyester. A thin conductive material could be placed into the channel in order to make a connection and then electroplate copper, or the channel could be filled with a catalyst and an electroless method could be used. In one embodiment, the top surface  302  of the flexible material  104  is coated in a silicone or other non-stick material, so that the applied conductive ink  300  can be easily wiped away leaving a filled channel  102 . Further, in addition to the conductive ink  300 , the channel  102  can be filled with additional conductive fillers  304  such as copper, silver, graphene, or a combination of these, or any other suitable conductive materials. In yet another embodiment, a metal layer could be deposited by vacuum evaporation. 
     Alternatively, as shown in  FIG. 4 , the conductor can be a cross-sectioned conductor  400  which in one embodiment is rectangular. For example, the rectangular cross-sectioned conductor  400  can be a tape or a section of a conductive mesh made from copper wire or other suitable conductive materials as is known in the art. 
     In an alternative embodiment shown in  FIG. 5 , the flexible material is comprised of at least two layers to control the channel depth of channel  504 . A first material layer  500  absorbs laser energy at a given wavelength, (such as 200 nm to 10.6 nm), and a bottom second layer  502  does not. Thus, when the required channel shape is cut with a laser or other suitable device, the depth is controlled to that corresponding to the first material&#39;s  500  thickness. 
       FIGS. 6A-C  illustrate an alternative embodiment which utilizes a cut  600  in the flexible material  602 . Specifically, a cut  600  is made in the flexible material  602  and then the cut  600  is opened up by bending. A conductor  604  such as a wire is then inserted into the opened cut  600  and the flexible material  602  is returned to a flat state, thus trapping the wire within the flexible material  602 . When using a flexible material  602  such as fabric for a thin wire, the compliance of the flexible material  602  prevents distortion of the substrate. 
     Additionally,  FIG. 7  illustrates the flexible material  702  with a channel  704  containing a conductor  706  as described above, but further comprising a second layer  700  over-laminated on top of the flexible base material  702 . The second layer  700  over-laminated on top can be used for multiple purposes, such as retaining the conductor  706 , sealing the conductor  706 , and/or presenting a smooth printable surface. Further, the second layer  700  can be comprised of any suitable material as is known in the art. 
       FIG. 8  illustrates a wire  800  with an additional coating  802  on its outside. The coating  802  has an initial state where the wire  800  is dry and has low adhesion, to make it easier to feed into the channel. The coating  802  has a second state where it becomes an adhesive and may become permanently cured at this point. For example, the wire  800  can have a hot melt coating  802  on it. The action of passing the flexible material with the conductor (the wire) in the channel through a pair of hot rollers will cause the adhesive to melt, sticking the wire  800  to the edges of the channel and, if required, the edges of the channel together. 
       FIGS. 9A-B  illustrate a wire  900  being guided into the channel  902  by a wire dispensing device  904 . The wire dispensing device  904  comprises a tip or dispensing head  906  that is engaged into the channel  902 , making the definition of the wire shape to be only the initial formation of the channel  902 . For example, the wire dispensing device  904  simply rides in the channel  902  without electrical control of position. To facilitate this in delicate flexible materials, the flexible material may be temporarily stiffened by means such as reducing the temperature or having the fabric pre-impregnated with a material such as starch or PVA that can be easily washed out after processing and potentially re-used, or any other suitable method as is known in the art. 
     In another embodiment, the dispensing tip is heated to a temperature that can locally melt fabric before dispensing the wire into the channel formed; the hot tip and dispenser can be followed by a relatively flat structure that seals the channel pushing the edges of the channel together whilst still hot and fluid. 
     What has been described above includes examples of the claimed subject matter. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.