Tagging devices are becoming commonplace for tracing and identifying parts and items of equipment both during and after production. One electronic form of tagging device is known as a radio frequency identification device (RFID). The RFID is usually in the form of a disc which contains electronics which can be programmed with a unique identification code. The disc can be ceramic and one particular type of RFID has a diameter of approximately 2.5 centimetres. However, RFIDs of different shapes, sizes and materials are available. After the disc has been programmed, the disc can be interrogated to determine the identification code (and therefore the article to which the disc is attached) by an appropriate scanning device. Conventionally, the disc is attached to an article by a clip-on holder which holds the disc in a manner which allows the disc to be exposed for scanning.

However, one of the limitations on the use of RFIDs is

that the electronics within the disc have a maximum survival temperature. Typically, the maximum temperature at which these types of devices will operate is of the order of 200°C. RFIDs are available which have survivability temperatures greater than 200°C. However, these tend to be expensive and are considerably larger. Normally, the electronics within the device will break down or be destroyed at temperatures above the survivability temperature. This is a particular problem, with, for example, vehicle parts which require to be painted, as ovens are commonly used to bake the paint and the operating temperature of an oven may be up to 235°C or greater.

Hence, to date, it has not been possible to successfully use existing small and cost effective RFIDs for vehicle parts which require to be placed in ovens to bake the paint on them, or any other high temperature applications where RFIDs are used.

In accordance with the present invention, there is provided a holder for a radio frequency identification device (RFID) having means to prevent overheating of the RFID.

Preferably, the holder protects the RFID from temperatures up to, or greater than 235°C.

Preferably, the means to prevent overheating comprises a heatsink. Alternatively, the means comprises a void surrounding the RFID. The void typically contains air.

In a preferred embodiment, the holder typically comprises a first and a second member, the members comprising a heatsink. The first and second members are typically adapted to be coupled together to hold an RFID. Preferably, the material for the first and

second members is polytetrafluoroethylene (PTFE).

In this embodiment, the material of the first and second members acts as a heat sink, thereby dissipating heat in the ambient air. This protects the RFID encased therein from heat damage. The use of PTFE in the manufacture of the members gives good thermal dissipation properties due to its heat resistance, chemical inertness and insulating properties.

The first and second members are typically retained in position by a retaining means. The retaining means is typically a spiral retaining ring. The spiral retaining ring typically engages an annular notch in one of the first and second members. Any conventional coupling means, such as a press-fit, snap-fit, screws, or the like, may be used.

One of the first and second members is typically provided with a second annular notch. An 0-ring seal is typically located in the notch. The O-ring typically provides an air-tight seal. If an 0-ring is used, one of the first and second members is provided with means for allowing trapped air to escape.

Typically, the means comprises an aperture in one of the first and second members.

Preferably, the holder includes a mounting device which permits the holder to be mounted to an article which is required to be identified by an RFID.

The mounting device typically comprises a third member which facilitates mounting of the holder to an article.

The third member is typically attached to the article by a clip or stud, inserted in an aperture in the third member. The third member is typically variable in

shape and/or configuration. This allows a user to select an appropriate mounting device for a particular article.

Preferably, the material of the holder or at least one of the members is substantially transparent to radio frequency electro-magnetic radiation. Typically, the material of the holder is thermally insulating. For example, the material may be polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE).

The third member may be manufactured from any plastics material. Typically, the plastics material may be PEEK. It may be coupled to one of the first and second members by any conventional means, but is preferably screwed thereto.

In an alternative embodiment, the invention provides a holder for an RFID having support means to support the RFID wherein the RFID is spaced from the holder and maintained within a void.

Typically, the support means comprises a first member and a second member which are adapted to be coupled together to define an enclosed void. Typically, the holder further comprises holding means on at least one of the members to hold the RFID in position within the internal void. Preferably, the holding means contacts only a portion of the surface of the RFID.

Typically, the remaining surface area of the RFID is surrounded by air in the void, when the first and second members are coupled together in use.

Typically also, only a portion of the surface of the RFID is contacted, and thus the RFID is at least

partially surrounded by the void and spaced from the first and second members.

An advantage of this embodiment is that the holder, by enclosing the RFID and providing for an air gap over a substantial portion of the surface area of the RFID, helps to thermally insulate the RFID from the atmosphere in which the holder is located.

Typically, the holding means engages the RFID adjacent to its peripheral edges to hold it in position within the internal void. Typically, when the first and second members are coupled together the outer surfaces of the RFID, or typically the majority of the outer surfaces, are in contact with air in the void.

Alternatively, the holding means may engage the RFID in a central aperture or recess in the RFID, so that the remaining surface is in contact with air in the void.

Typically, the holding means comprises a recess in one or both of the members in which an edge of the RFID locates. Alternatively, or in addition, the holding means may comprise projections which engage a central recess in the RFID.

Preferably, the first and second members are coupled together by a press-fit or snap-fit assembly.

Alternatively, the first and second members may be a screw fit assembly.

Preferably, the holder also includes a mounting device which permits the holder to be mounted on an article to be identified by the RFID.

Typically, the mounting device comprises a clip which

engages with a portion of an article to which the holder is to be attached. Alternatively, the mounting device may comprise sockets or pins formed in the first or the second member which engage with corresponding pins or sockets on the article to which the holder is to be attached.

Preferably, the material of the holder or at least one of the members is substantially transparent to radio frequency electro-magnetic radiation. Typically, the material of the holder is thermally insulating. For example, the material may be polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE).

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:- Fig. 1 is a rear view of a first example of a holder for a radio frequency identification device; Fig. 2 is a cross-sectional view along the line BB in Fig. 1; Fig. 3 is a front view of the holder shown in Figs. 1 and 2 with the holder attached to an article; Fig. 4 is a cross-sectional view along the line AA in Fig. 3; Fig. 5 is a front view of a second example of a holder for a radio frequency identification device; Fig. 6 is a cross-sectional view along the line DD in Fig. 5; Fig. 7 is a bottom view of a third example of a holder for a radio frequency identification device; and

Fig. 8 is a cross-sectional view along the line CC in Fig. 7; Fig. 9a is a sectional side elevation of a first member of an alternative holder; Fig. 9b is an enlarged view of a portion of the first member to show the detail of a notch therein; Figs 10a and 10b are respective side and end elevations of a second member of the alternative holder; Figs lla and llb are respective side and end elevations of a third member of the alternative holder; and Fig. 12 is a partly sectional view of the members shown in Figs 9 to 11 when assembled to form the holder.

Fig. 1 shows the rear view of a holder 1 which includes a body member 2 which has a clip portion 3. The body member 2 also has a recessed section 4.

Fig. 2 is a cross-sectional view through the holder 1 along the line BB in Fig. 1. In Fig. 2 it can be seen that the holder 1 also includes a snap-on cap 5 and a radio frequency identification device (RFID) 6 is located in a recess 7 in the body member 2 and held in the recess by a shoulder 8 on the inside of the cap 5.

The cap 5 includes a circumferentially extending flange 9 with a shoulder 10 which engages with a circumferentially extending shoulder 11 on the body member 2. The flange 9 is resilient and is deformed by the shoulder 11 on the body member 2 and snaps into the position shown in Fig. 2 in which the shoulders 10 and 11 engage with each other to couple the cap 5 and the body member 2 together. The RFID 6 may be, for example, a Motorola Indala (TM) RFID model IT254e.

In addition, the body member 2 has a recess 12 adjacent a surface of the RFID 6 and the cap 5 has a corresponding recess 13 adjacent the opposite surface of the RFID 6. The recesses 12,13 provide an air gap between the main surfaces of the RFID 6 and the material of the body member 2 and cap 5.

Typically, the material of the body member 1 and the cap 5 is transparent or substantially transparent to radio frequency electro-magnetic radiation. This permits the RFID 6 to be read by an appropriate scanner without requiring the RFID 6 to be removed from the holder 1.

In use, the holder 1 may be attached to an article 15 by means of the clip 3, as shown in Figs. 3 and 4. For example, the article 15 may be a panel for a vehicle which requires to be painted and then baked in an oven in order to cure the paint, primer or basecoat.

Typically, the survivability temperature for the RFID 6, such as a Motorola IT254e RFID, is a maximum of 200°C. However, the temperature of the oven into which the article 15 is placed may be up to 235°C. However, by virtue of the thermally insulating material chosen for the cap 5 and the body member 1 and that the cap 5 and body member 2 when assembled to form the holder 1 completely enclose the RFID 6, the holder 1 helps to thermally insulate the RFID 6 from the ambient temperature within the oven. In addition, the presence of the recesses 12,13 provide an air gap over a substantial portion of the surfaces of the RFID 6 and this air gap further helps insulation of the RFID 6 by helping to thermally insulate the RFID 6 from the material of the cap 5 and body member 2.

Therefore, although the ambient temperature within the oven may be as high as 235°C, the actual temperature seen by the RFID 6 within the holder 1 is within the survivability limits of the RFID 6 for the length of time that the RFID 6 is in the oven.

Figs. 5 and 6 show a second example of holder 20 which includes two half sections 21,22 which fit together by virtue of a pin hole arrangement 23 in the body members 21,22 which permits the body members 21,22 to be assembled by a press fit. As shown in Fig. 6, the RFID 6 is held within the holder 20 by means of projections 24,25 on the respective body members 21,22 which engage with a central recess 26 in the RFID 6. Within each body member 21,22 is a toroidal recess 27 which provides an air gap between the surfaces of the RFID 6 and the material of the body members 21,22.

When assembled, the holder 20 has four sockets 28.

These permit the holder 20 to be mounted on an article to be tagged by engaging studs (not shown) which are mounted on the article in two of the sockets 28 in the holder 20.

The material from which the holder 20 is manufactured may be the same material as the material from which the holder 1 is manufactured.

Figs. 7 and 8 show a third example of a holder 30.

Fig. 8 is a cross-sectional view along the line CC in Fig. 7. The holder 30 includes a body member 31 which is engaged with a cap 32 by means of a circumferentially extending recess 33 in the cap 32 which engages with a circumferentially extending ridge 34 in the body member 31. The body member 31 is also provided with two sockets 28 which permit the holder 30

to be attached to an article to be tagged by engaging the sockets 28 with corresponding studs (not shown) mounted on the article, in a similar manner to the holder 20.

The body member 31 is provided with two flanges 35, which define a central recess 36 and side recesses 37.

When the cap 32 is attached to the body member 31, as shown in Fig. 8, the edges of the RFID 6 are located in notches 38,39 in the body member 31 and the cap 32, respectively, to hold the RFID 6 in position in the recess 36. The recess 36 provides an air gap around the RFID 6 which helps to thermally insulate the RFID 6 from the material of the holder 30.

An advantage of these embodiments of the present invention is that by providing a holder which (i) completely encloses the RFID 6; (ii) is made of a thermally insulating material; and (iii) provides an air gap around the RFID 6, the temperature"seen"by the RFID 6 in high temperature applications, such as in ovens, is less than the actual ambient temperature within the oven. Hence, this enables a conventional RFID 6 to be used in conditions where the ambient temperature is greater than the rated survivability temperature of the RFID 6.

Figs 9 to 12 show an alternative holder for an RFID in accordance with the present invention. Figs 9a and 9b show a first member 50 which is advantageously manufactured from PTFE. The PTFE used is preferably grade A, class 1 and stress relieved. The first member 50 is provided with a central aperture 52 which extends through approximately half the depth of the first member 50 in this embodiment. The aperture 52 provides a surface 54 on which an RFID 56 is placed in use.

Figs 10a and 10b show a second member 60 which is also advantageously manufactured from PTFE as before. The second member 60 has a first end 62 which, in use, is fitted into the aperture 52 of the first member 50, as best shown in Fig. 12. Thus, the first end 62 contacts the RFID 56, thereby holding it between the surface 54 and the first end 62 of the second member 60.

The member 60 is provided with an annular notch 64 into which an O-ring seal 74 or the like is positioned before the first and second members 50,60 are brought together. The O-ring 74 provides an air-tight seal when the second member 60 is inserted into the first member 50, shown in Fig. 12. It should be noted that the 0-ring 74 is not essential to the invention and may be omitted.

A central bore 66 is provided in the second member 60.

The bore 66 allows air which becomes entrapped when the first and second members 50,60 are coupled together, to be vented. In addition, the central bore 66 allows for thermal expansion of the air enclosed in the holder as it is heated. Bore 66 narrows to a smaller bore 68 at the end which contacts the RFID 56. This smaller bore 68 is of the order of lmm in diameter, thus minimising the amount of surface area of the RFID 56 which is not in contact with the second member 60.

Second member 60 is provided with a counter-sunk bore 70 into which a first end 82 of a third member 80 is fitted. The third member 80 is advantageously manufactured from PEEK, although any plastics material may be used. PTFE need not be used, as the third member 80 is not in direct contact with the RFID 56 and does not constitute part of the heatsink.

As shown in Fig. 12, the first end 82 of member 80 is inserted into the bore 70. The two members 60,80 are held together by, for example, plastite screws 88, preferably No 4*8mm. The screws 88 are fitted into corresponding holes 72 and 84 on the respective second and third members 60,80. However, any conventional securing means may be used to secure members 60,80 together.

To allow the holder to be secured to an article, a slot 86 is formed in the third member 80. A metal clip 90 or stud (not shown) may be inserted into the slot 86.

The clip 90 or stud is then coupled to a suitable retaining means on the article to allow the RFID holder to be attached thereto.

It should be noted that the third member 80 may be varied depending upon the article to which the holder is to be secured. In addition, the type of clip, stud or the like can also be varied, again dependent upon the article. Thus, this embodiment is not limited to the example shown.

An advantage of these embodiments of the present invention is that by providing a holder which (i) completely encloses the RFID 56; and (ii) is made of a thermally insulating material, the temperature"seen" by the RFID 56 in high temperature applications, such as in ovens, is less than the actual ambient temperature within the oven.

The use of PTFE with its special properties extends the time in which the RFID 56 may be exposed to higher temperatures. In some applications this may be another 15-20%. In addition, as there is no void around the RFID 56, the air circulation is kept to a minimum,

which has been found to give improved performance.

These features enable a conventional RFID 56 to be used in conditions where the ambient temperature is greater than the rated survivability temperature of the RFID 56.

Modifications and improvements may be made without departing from the scope of the invention.