GB2472025A

GB2472025A - Identification device

Info

Publication number: GB2472025A
Application number: GB0912673A
Authority: GB
Inventors: Tilak Dias; Anura Fernando
Original assignee: ENTELLFIBRES Ltd; University of Manchester
Current assignee: ENTELLFIBRES Ltd
Priority date: 2009-07-21
Filing date: 2009-07-21
Publication date: 2011-01-26
Also published as: GB0912673D0

Abstract

An identification device comprises a semi-conductor chip 2 mounted on a substrate 4 forming an antena 6 extending from opposite sides of the chip and a yarn 10 disposed over the substrate such that the chip is between the substrate and the yarn. Preferably a UV light curable resin adhesive 12 bonds the yarn and substrate. The yarn may be mono or multi filament and the substrate may have a lateral dimension equal to the yarn thickness. The substrate may be trimmed to its lateral dimension by retractable blades in one jaw of a two jaw tool used to bring and hold the substrate and yarn together during bonding. During assembly the yarn is preferably held horizontal to minimise gravitational or capillary movement of resin along the yarn. The filaments of a multi-filament yarn may make room for the chip to make for little variation in lateral dimensions of the device. The device is preferably an RFID device used in woven braided, knitted or embroidered fabric for use at the point of sale or in stocktaking. The device may be connected to a power source by conductive filaments in the yarn.

Description

Identification Devices This invention relates to identification devices. Such devices are used to identify products, either by direct application or on tags or labels, and could also be used for locating personnel. The present invention is directed particularly at individual such devices which can be easily handled prior to and during use.

According to the present invention an identification device comprises a semi-conductor chip mounted on a substrate which form antenna extending from opposite sides of the chip. Such a chip-substrate combination is generally referred to as a "tag".

The substrate and chip are secured to a length of yarn, preferably with the chip between the substrate and the yarn. Both the yarn and the substrate will normally have sufficient flexibility to ensure that the engagement between them is smooth and continuous, with the composite product having a substantially uniform cross-section, with the largest variation of course in the region of the chip itself The yarn is normally secured to the substrate and transponder with a resin.

While sufficient bonding can be achieved between the substrate and the monofilarnents yarn, we have found that with a multifilament yarn the resin can impregnate the yarn between the filaments, and thereby provide a stronger attachment to the substrate.

The invention is also directed at a method of making an identification device of the kind described above. The method comprises the sequential steps of: a) mounting a semi-conductor chip on a substrate forming antenna extending from opposite sides of the chip, with the antenna aligned on a common axis; b) offering up a length of yarn to the chip-substrate combination; c) disposing an adhesive resin between the length of yarn and the combination; d) bringing the length of yarn and the combination together with the resin therebetween; and e) curing the resin to fix the yarn to the substrate and chip.

Suitable semi-conductor chips for use in this invention are available, and can be supplied already mounted on a substrate forming the antenna, as radio frequency identification (RFID) tags. Accordingly, in the method of the invention the initial mounting of the chip on the substrate step can be omitted if the tag is provided in this form. The adhesive resin may be applied to the length of yarn or to the substrate and chip, or indeed as a separate element disposed between the yarn and the chip-substrate combination or tag, prior to them being brought together.

The substrate upon which the chip is mounted normally has a lateral dimension greater than the thickness of the yarn to which it is to be secured, one reason for which is ease of handling. In the method of the invention the substrate is normally trimmed so that its lateral dimension substantially matches that of the chip, and preferably also that of the yarn. However, the selected lateral dimension for the substrate can be determined with reference to the yarn to which it is to be attached. In some cases it will be beneficial to have the substrate to a small extent wrapping around the yarn, particularly if it is wished to enlarge the area of adhesive contact. This may be the case if the yarn is monofilament. Generally though, it is preferred that the substrate does not extend as much as half way around the yarn. Preferably its lateral extent is equal to no more than one third of the yarn circumference.

In order to receive and/or send a good signal, the antenna in identification devices of the invention may be bent into a non-linear shape. By using yarns capable of plastic deformation, the invention enables this to be readily accomplished. Many polymeric yams are capable of plastic deformation, and if the deformation if thermoplastic the heated composite can be easily shaped in whatever fashion is desired.

This can be accomplished in the method of the invention during the curing step, which will normally involve the application of heat energy in some form.

The invention will now be described by way of example and with reference to the accompanying drawings wherein: FIGURE 1 shows in plan view a tag in the form of a semi-conductor chip and two laterally extending antenna mounted on a substrate; FIGURE 2 shows the disposition of a yarn and substrate carrying the transponder prior to their attachment; FIGURE 3 shows a side view of apparatus for securing the transponder and substrate to the yarn in a method according to the invention; and FIGURE 4 shows an end view of the device of Figure 3.

As shown in Figure 1 a semiconductor chip 2 is mounted on a substrate 4 with antenna 6 extending in opposite directions therefrom. Such chip-substrate combinations are commonly known as RFID tags, and are available in strip form, from a number of companies such as Hitachi Ltd. Tagsys RFID; Avery Dennison RFID, and Alien Technology Corporation. The antenna may be formed by sputtering or electro-deposition of conductive material onto the substrate with their ends located to make appropriate contact with the chip when it is subsequently affixed. Alternatively, the substrate itself can be conductive with its extent on opposite sides of the location of the transponder suitably isolated from each other. Before being applied to the yam as described below, the substrate shown in Figure 1 will be trimmed as indicated by the broken lines 8 such that the antenna and chip have substantially similar lateral dimensions.

Figure 2 shows the trimmed chip-substrate combination from Figure 1 in juxtaposition with a length of yam 10 ready for securement thereto by a resin 12 which is provided in the figure shown in the form of a strip. Alternatively of course, the adhesive can be applied to either or both of the yarn and chip-substrate combination The yam illustrated is a monofilarnent, and the adhesive and transponder substrate will wrap around the surface of the yarn when the bond is made by the resin. The chip itself will form a small projection on the resultant device, but depending on the material of the yarn which will normally be polymeric, the transponder will to a small extent at least, embed itself within the body of the yam, reducing of any projection. In order to cure the resin and fix the substrate and chip to the yarn, radiation energy will be applied typically in the form of ultraviolet light, while the elements are held together.

Figures 3 and 4 illustrate a means by which an identification device according to the invention can be fabricated. A length of yarn 10 is drawn through the fabrication station illustrated in the direction shown. It passes through two stages. At the first, an adhesive is applied to a length of the yarn corresponding to the length of the substrate upon which the chip is mounted, and which is to be secured to the yarn. The yam 10 is then advanced to locate the length bearing the resin directly over the chip-substrate combination which has been previously assembled and located on the lower of two jaws 14 and 16. With the yam suitably located on the upper jaw 16, directly over the chip-substrate combination on the lower jaw 14, the two jaws are brought together. While they are held together, radiant energy in the form of ultraviolet light or from some other energy source is applied to cure the resin and secure the substrate and chip; the tag, to the yarn. The jaws are then separated, and the yam advanced to remove the fabricated identification device. The length of yarn forming the device can then be cut from the remainder of the yam, or retained on a chosen length depending upon its intended use.

Figure 4 shows how the substrate bearing the semi-conductor chip is located on the lower jaw 14. A plurality of chip-substrate combinations are provided in strip form, which is advanced in a stepwise fashion as required, towards the jaws 14 and 16. When required, the strip is advanced to locate the transponder and the aligned antennas at the appropriate position on the lower jaw, and retractable blades 22 extend downwards from the upper jaw 16, to trim the substrate as described above, to the required lateral dimension. The yarn, with adhesive applied to the appropriate length, is then advanced between the jaws and the jaws then brought together to secure the substrate and chip to the yarn, as described above.

It will be appreciated that the application of the resin can be to the chip-substrate combination rather than the yarn, but generally it is preferred either to apply it to the yarn, or provide the resin in strip form as described above with reference to Figure 2. In other words, application of the resin to the chip-substrate combination is preferably avoided to minimise wastage. Movement of the yarn in a horizontal, rather than a vertical direction also serves to minimise wastage as there is reduced gravitational or capillary movement of the resin along the length of the yarn beyond that which is required.

Although in the above description reference has been made to a monofilament yarn, it will be appreciated that multiple yarns can be equally effective and have the advantage of absorbing the securing resin within its structure between the filaments.

There is the additional advantage that the filaments in a multifilament yam are better adapted to make room for the semi-conductor chip on the substrate, with the result that the resultant identification device can have lateral dimensions which vary very little over its length, even in the region of the chip itself Although there is no specific requirement for the material of the yarn forming a basic element of an identification device according to the invention, it would normally be polymeric. Polyester yarns can be used are dtex 18 f-12 and dtex 193 fi. Preferably the yarn is plastic and most preferably thermoplastic, enabling it to be bent with the transponder antenna to maximise the ability of the transponder to receive and send signals. The resin used for securing the transponder-substrate combination to the yarn will also be a factor in settling the final shape of the antenna. Suitable resins are Dymax DYM9001-E-v3.O and Dymax DYM9001-E-v3.5 Depending upon the flexibility retained in an identification device according to the invention, it can be incorporated in a woven, braided, knitted, or embroidered fabric.

One or a number of chip-substrate combinations or tags can be installed in a common length of yam which is used in a fabric either as a garment or for any other purpose.

Such installation can use the method disclosed in International Publication No. WO 2006/123,133, referred to above, incorporated by reference. In some cases the transponder may include a miniature power source or be connected through conductive filaments in the yarn to a remote power source, but generally it will normally be reactive rather than proactive. A primary use of the device would be as a radio frequency identification device, which itself can have many applications. One environment in which they could be used is in retail premises, either at the point of sale or in stocktaking.

Claims

CLAIMS: 1. An identification device comprising a semi-conductor chip mounted on a substrate forming antenna extending from opposite sides of the chip, and a yarn disposed over the substrate and secured thereto with the chip between the substrate and the yarn.
2. A device according to Claim 1 wherein the yarn comprises multiple filaments.
3. A device according to Claim I or Claim 2 wherein the substrate with the chip mounted thereon has a lateral dimension substantially equal to the thickness of the yarn.
4. A method of making an identification device comprising: a) mounting a semi-conductor chip on a substrate forming antenna extending from opposite sides of the chip, with the antenna aligned on a common axis; b) offering up a length of yarn to the chip and substrate; c) disposing an adhesive resin between the length of yarn and the substrate and bringing the length of yarn and the transponder together with the resin therebetween; and d) curing the resin to fix the yarn to the substrate and the chip.
5. A method according to Claim 4 wherein the resin is applied to the length of the yam.
6. A method according to Claim 4 wherein the resin is applied to the substrate and transponder.
7. A method according to any of Claims 4 to 6 wherein the resin is cured by exposure to ultra-violet light.
8. A method according to any of Claims 4 to 7 wherein the yarn is a multi-filament yarn.
9. A method according to any of Claims 4 to 8 wherein the substrate with the transponder mounted thereon has a lateral dimension substantially equal to the thickness of the yarn.