EHLEN MATHIAS MARTIN ERNEST (NZ)
| WO2000042569A1 | 2000-07-20 | |||
| WO2006062175A1 | 2006-06-15 |
| US20060000915A1 | 2006-01-05 | |||
| US20060255945A1 | 2006-11-16 | |||
| US20060091225A1 | 2006-05-04 | |||
| US20060032926A1 | 2006-02-16 |
CLAIMS
1. A method of forming an " RFID tag comprising the steps of: a. providing a composite sheet comprising a dielectric sheet sandwiched between first and second conductive sheets; b. forming an opening through the first conductive sheet and dielectric . sheet through to the second conductive sheet; c. inserting an RFID chip into the opening in the dielectric sheet; and d. coupling the chip to the first and second conductive sheets.
2. A method of forming an RFID tag as claimed in claim 1 wherein the first and second conductive sheets are coupled together along one edge of the composite sheet.
3. A method of forming an RFID tag as claimed in claim 2 wherein the chip is coupled to the first and second conductive sheets proximate a first edge of the composite sheet and the first and second conductive sheets are coupled together along a second edge of the composite sheet remote from the first edge.
4. A method of forming an RFID tag as claimed in claim 3 wherein the chip is coupled to the first and second conductive sheets at a point spaced from the second edge by about a quarter wavelength at a desired operating frequency of the tag.
5. A method of forming an RFID tag as claimed in any one of claims 2 to 4 wherein an electrical conduction path couples the first and second conductive sheets together.
6. A method of forming an RFID tag as claimed in any one of claims 2 to 4 wherein the first and second conductive sheets are capacitively coupled together.
7. A method of forming an RFID tag as claimed in claim 6 wherein the capacitive coupling and inductance of the first and second conductive sheets is matched so as to form a resonant circuit at a desired operating frequency of the tag.
8. A method of forming an RFlD tag as claimed in any one of the preceding claims including the further step of inserting a resilient material into the opening.
9. A method as claimed in claim 8 wherein the resilient material is a foam.
10. A method of forming an RFID tag as claimed in any one of the preceding claims wherein the first conductive sheet is substantially rectangular in plan.
11. A method of forming an RFID tag as claimed in any one of the preceding claims wherein the first conductive sheet is the same size or smaller than the second conductive sheet.
12. A method of forming an RFID tag as claimed in any one of the preceding claims wherein the first conductive sheet is formed of copper, aluminium or stainless steel.
5 13. A method of forming an RFID tag as claimed in any one of the preceding claims wherein the dielectric sheet is formed of polyethylene or polypropylene.
14. A method as claimed in any one of the preceding claims wherein the LO . dielectric sheet is greater than 3mm thick.
15. A method as claimed in any one of the preceding claims wherein the dielectric sheet is greater than 4mm thick.
L5 16. A method as claimed in any one of the preceding claims wherein the dielectric sheet is about 6mm thick.
17. A method of forming an RFID tag as claimed in any one of the preceding claims wherein the composite sheet is a construction grade building
10 panel.
18. A method of forming an RFID tag as claimed in any one of the preceding claims wherein holes are formed in the tag to facilitate mounting of the tag.
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19. A method of forming an RFID tag as claimed in any one of the preceding claims wherein a housing is formed about the tag.
20. An RFID tag comprising: a. a composite sheet comprising a dielectric sheet sandwiched between first and second conductive sheets; and b. an RFID chip located within a cavity in the dielectric sheet and coupled to the first and second conductive sheets.
21. An RFID tag as claimed in claim 20 wherein the first and second conductive sheets are coupled together along one edge of the composite sheet.
22. An RFID tag as claimed in claim 21 wherein the chip is coupled to the first and second conductive sheets proximate a first edge of the composite sheet and the first and second conductive sheets are coupled together along a second edge of the composite sheet remote from the first edge. •
23. An RFID tag as claimed in claim 22 wherein the chip is coupled to the first and second conductive sheets at a point spaced from the second edge by about a quarter wavelength at a desired operating frequency of the tag.
24. An RFID tag as claimed in any one of claims 20 to 23 wherein an electrical conduction path couples the first and second conductive sheets together.
25. An RFID tag as claimed in any one of claims 20 to 23 wherein the first and second conductive sheets are capacitively coupled together.
26. An RFID tag as claimed in claim 25 wherein the capacitive coupling and inductance of the first and second conductive sheets is matched so as to form a resonant circuit at a desired operating frequency of the tag.
27. An RFID tag as claimed in any one of claims 20 to 26 including a resilient material inserted into the opening.
28. An RFID tag as claimed in claim 27 wherein the resilient material is a foam.
29. An RFID tag as claimed in any one of claims 20 to 28 wherein the first conductive sheet is substantially rectangular in plan.
30. An RFID tag as claimed in any one of claims 20 to 29 wherein the first conductive sheet is the same size or smaller than the second conductive sheet.
31. An RFID tag as claimed in any one of claims 20 to 30 wherein the first conductive sheet is formed of copper, aluminium or stainless steel.
32. An RFID tag as claimed in any one of claims 20 to 31 wherein the dielectric sheet is formed of polyethylene or polypropylene.
33. An RFID tag as claimed in claim any one of claims 20 to 32 wherein the dielectric sheet is greater than 3mm thick.
34. An RFID tag as claimed in any one of claims 20 to 32 wherein the dielectric sheet is greater than 4mm thick.
35. An RFID tag as claimed in any one of claims 20 to 32 wherein the dielectric sheet is about 6mm thick.
36. An RFID tag as claimed in any one of claims 20 to 35 wherein the composite sheet is a construction grade building panel.
37. An RFID tag as claimed in any one of claims 20 to 36 wherein holes are formed in the tag to facilitate mounting of the tag.
38. An RFID tag as claimed in any one of claims 20 to 37 wherein a housing is formed about the tag.
39. A method of forming an RFID tag comprising the steps of: a. providing a composite sheet comprising a dielectric sheet secured to a first conductive sheet; b. dividing the first conductive sheet into first and second portions; and c. coupling an RFID chip to the first and second portions.
40. A method of forming an RFID tag as claimed in claim 39 wherein the chip is coupled to the first and second portions of the conductive sheet by inserting the chip between the first and second portions to form electrical connections therewith.
41. A method of forming an RFID tag as claimed in claim 40 wherein the chip is forced into the dielectric sheet.
42. A method of forming an RFID tag as claimed in claim 41 wherein the chip is forced into the dielectric sheet to a level at or below the surface of the sheet.
43.A method of forming an RFID tag as claimed in claim 39 wherein the chip is capacitively coupled to the first and second portions.
44.A method of forming an RFID tag as claimed in any one of claims 39 to 43 wherein the composite sheet has a second conductive sheet secured to the other side of the dielectric sheet.
45. A method of forming an RFID tag as claimed in any one of claims 39 to 44 wherein the first and second portions are divided so as to form a dipole antenna.
46. A method of forming an RFlD tag as claimed in claim 45 wherein each portion is about a quarter wavelength long at one or two desired frequencies of operation.
47. A method of forming an RFID tag as claimed in any one of claims 39 to 44 wherein the first and second portions are divided unequally so as to form a monopole and a stub element.
48. A method of forming an RFID tag as claimed in claim 47 wherein the monopole is about a quarter wavelength long at the desired frequency of operation.
49. A method of forming an RFID tag as claimed in any one of claims 39 to 48 wherein the first conductive sheet is copper, aluminium or stainless steel.
50. A method of forming an RFID tag as claimed in any one of claims 39 to 49 wherein the dielectric material is polyethylene or polypropylene.
51. A method as claimed in any one of claims 39 to 50 wherein the dielectric sheet is greater than 3mm thick.
52.A method as claimed in any one of claims 39 to 50 wherein the dielectric sheet is greater than 4mm thick.
53.A method as claimed in any one of claims 39 to 50 wherein the dielectric sheet is about 6mm thick.
54.A method of forming an RFID tag as claimed in any one of claims 39 to 53 wherein holes are formed in the tag to assist in mounting the tag.
55.A method of forming an RFID tag as claimed in any one of claims 39 to 54 wherein a housing is provided about the tag.
56. An RFID tag comprising: a. a composite sheet comprising a dielectric sheet secured to a first conductive sheet, wherein the first conductive sheet is divided into first and second portions; and b. an RFID chip coupled to the first and second portions.
57. An RFID tag as claimed in claim 56 wherein the chip is coupled to the first and second portions of the conductive sheet by electrical connections therewith.
58. An RFID tag as claimed in claim 57 wherein the chip is embedded into the dielectric sheet.
59. An RFID tag as claimed in claim 58 wherein the chip is embedded into the dielectric sheet to a level at or below the surface of the sheet.
60. An RFID tag as claimed in claim 56 wherein the chip is capacitively coupled to the first and second portions.
61. An RFID tag as claimed in any one of claims 56 to 60 wherein the composite sheet has a second conductive sheet secured to the other side of the dielectric sheet.
62. An RFID tag as claimed in any one of claims 56 to 61 wherein the first and second portions are divided so as to form a dipole antenna.
63.An RFID tag as claimed in claim 62 wherein each portion is about a quarter wavelength long at one or two desired frequencies of operation.
64.An RFlD tag as claimed in any one of claims 56 to 61 wherein the first and second portions are divided unequally so as to form a monopole antenna and a stub element.
65.An RFID tag as claimed in claim 64 wherein the monopole is about a quarter wavelength long at the desired frequency of operation.
66.An RFID tag as claimed in any one of claims 56 to 65 wherein the first conductive sheet is copper, aluminium or stainless steel.
67.An RFID tag as claimed in any one of claims 56 to 66 wherein the dielectric material is polyethylene or polypropylene.
68. An RFID tag as claimed in any one of claims 56 to 67 wherein the dielectric sheet is greater than 3mm thick.
69. An RFID tag as claimed in any one of claims 56 to 67 wherein the dielectric sheet is greater than 4mm thick.
70.An RFID tag as claimed in any one of claims 56 to 67 wherein the dielectric sheet is about 6mm thick.
71.An RFID tag as claimed in any one of claims 56 to 70 wherein mounting holes are formed in the tag.
72.A method of forming an RFID tag as claimed in any one of claims 56 to 71 wherein a housing is provided about the tag. |
AN RFID TAG AND A METHOD OF FORMING AN RFlD TAG
FIELD OF THE INVENTION
This invention relates to an RFID tag (a radio frequency identification tag) and a method of forming an RFID tag. According to one aspect an RFID chip is embedded within an opening in a composite sheet. In another embodiment a conductive sheet on a dielectric sheet is divided into two parts and an RFID chip drives the two parts.
BACKGROUND OF THE INVENTION
Passive UHF RFID tags are generally constructed by either etching a printed circuit board, or by printing conductive ink onto a substrate. Solid state dielectrics and additional conductive sheets are often added to a tag to make- it robust, or to provide the desired operating characteristics such as the ability to operate near metal objects. Such techniques often require complex manufacturing processes and/or use expensive materials making the tags expensive.
It would be desirable to provide a robust, economical and compact passive RFID tag and method of construction or to at least provide the public with a useful choice.
EXEMPLARY EMBODIMENTS
According to one exemplary embodiment there is provided a method of forming an RFID tag comprising the steps of: a. providing a composite sheet comprising a dielectric sheet sandwiched between first and second conductive sheets; b. forming an opening through the first conductive sheet and dielectric sheet through to the second conductive sheet; c. inserting an RFID chip into the opening in the dielectric sheet; and d. coupling the chip to the first and second conductive sheets.
According to another exemplary embodiment there is provided an- RFID tag comprising: a. ■ a composite sheet comprising a dielectric sheet sandwiched between first and second conductive sheets; and b. an RFID chip located within a cavity in the dielectric sheet and coupled to the first and second conductive sheets.
According to a further exemplary embodiment there is provided a method of forming an RFID tag comprising the steps of: a. providing a composite sheet comprising a dielectric sheet secured to a first conductive sheet; b. dividing the first conductive sheet into first and second portions; and c. coupling an RFID chip to the first and second portions.
According to another exemplary embodiment there is provided an RFID tag comprising: a. a composite sheet comprising a dielectric sheet secured to a first conductive sheet, wherein the first conductive sheet is divided into first and second portions; and b. an RFID chip coupled to the first and second portions.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention.
Figure 1 shows a perspective view of a composite sheet for forming an antenna according to one embodiment;
Figure 2 shows the composite sheet of figure 1 with an opening formed therein;
Figure 3 shows an exploded view of the components of an RFlD antenna according to one embodiment;
Figure 4 shows an assembled RFlD tag;
Figure 5 shows an RFID tag and a protective cover;
Figure 6 shows an RFiD tag with a protective cover;
Figure 7 shows a perspective view of composite sheet for forming an RFID tag according to another embodiment; 5
Figure 8 shows a groove formed in the composite sheet shown in figure 7;
Figure 9 shows an RFID chip applied to the composite sheet of figure 8;
LO Figure 10 shows an RFlD tag formed according to a further embodiment;
Figure 11 shows an RFID tag formed according to a further embodiment;
Figure 12 shows an RFID tag formed according to a further embodiment; L5
Figure 13 shows an RFID tag formed according to a further embodiment; and
Figure 14 shows an RFID tag formed according to a further embodiment; >0
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
In a first embodiment an RFID tag utilizes an antenna that may be formed from a composite sheet such as a construction grade building panel. A method of 15 forming such an RFID tag will now be described with reference to figures 1 to 6.
Figure 1 shows a composite sheet 1 consisting of a dielectric layer 2 sandwiched between conductive sheets 3 and 4. The conductive sheets 3 and 4 may be
copper, aluminium, stainless steel or any other suitable conductive material. The dielectric sheet 2 may be formed of any suitable dielectric material, polyethylene or polypropylene are preferred as these materials are inexpensive and are commonly employed in low cost construction grade building materials which can be used in this embodiment. The dielectric sheet is preferably more than 3 mm thick and preferably more than 4 mm thick. A dielectric sheet of about 6 mm thickness has been found provide satisfactory results. Lesser thicknesses will operate with a lesser bandwidth.
As shown in figure 2 an opening 5 may be formed in conductive sheet 3 and dielectric sheet 2 of composite sheet 1 by any suitable method such as drilling, milling, routing etc. As shown in figures 3 and 4 a conductive coupling element 7 may be placed within an opening 5 with a chip 6 placed on top of it. Conductive coupling 7 provides capacitive coupling with conductive sheet 3. A resilient foam insert 9 may be applied on top of RFID chip 6 to retain it in place.
Sheets 3 and 4 may be capacitively coupled together by coupling strip 8 along an edge of composite sheet remote from opening 5. Coupling strip 8 may include a dielectric layer between a conductive coupling sheet and conductive sheets 3 and 4. The capacitance of the coupling may be adjusted so that the capacitance of the coupling strip 8 and the inductance of the antenna form of a resonant circuit at a design operating frequency of the RFID tag. RFID chip 6 is preferably held to conductive sheet 3 at a position a quarter of a wavelength away from the edge of conductive sheet 3 proximate coupling strip 8. A protective housing a 10 may be provided about the RFID tag to provide additional protection, if required.
In another embodiment the foam insert 9 may be replaced with a dielectric substance such as glue, silicon paste, or epoxy resin.
Referring now to figure those 7 to 9 an alternative embodiment will be described. In this embodiment a composite sheet 21 of the same form as composite sheet 1 of the previous embodiment is used. Composite sheet 21 consists of a dielectric sheet 22 sandwiched between conductive sheets 23 and 24. A groove 25 is formed in conductive sheet 23 to form portions 23a and 23b. In this embodiment potion 23a forms a monopole antenna and portion 23b forms of a stub. In the embodiment shown in figure 9 an RFID chip 26 is positioned to the groove 25 so that it is.capacitively coupled to portions 23a and 23b. In another embodiment potions 23a and 23b may be of the same size so that a dielectric antenna is formed. In yet another embodiment the RFID chip may be affixed using an RFID strap which contains the RFID chip and small quantities of conductive material in a sticky label format, or similar.
Figure 10 shows a further embodiment, similar to figure 9 (and using the same reference numerals), in which RFID chip 26 has been forced into dielectric material 22 so as to be embedded within dielectric material 22 and conductively coupled to portions 23a and 23b. This arrangement has the advantage that RFID chip 26 is at or below the surface of composite sheet 21 and is protected thereby.
Figure 1 1 shows another embodiment in which a nonrectangular geometry is employed. It will be appreciated by one skilled in the field at a variety of geometries may be employed depending upon the requirements of a particular application. In this embodiment a large antenna portion 23c and a small
triangular stub 23d are formed by groove 27 dividing conductive sheet 23. RFID chip 26 is capacitively coupled to portions 23c and 23d.
Figure 12 shows an embodiment, similar to the embodiment of figures 1 to 6 in which apertures 1 1 are formed through composite sheet 1 to facilitate mounting of the RFID tag. In this embodiment capacitive coupling 12 extends along only a portion of an edge of composite sheet 1.
Figure 13 shows an embodiment in which portions of conductive sheet 14 have been removed from regions 13 to provide improved operation of over a broad bandwidth.
Figure 14 shows a further embodiment in which a plurality of rivets 15 are provided along an edge to electrically couple conductive sheets 16 and 17 along one edge.
These embodiments offer advantages over prior techniques of offering robust mechanical protection for the RFID chip, as well removing the requirement to etch copper from a PCB, or to print conductive ink onto a substrate. The composite sheet may be efficiently and accurately formed from larger sheets of construction grade building panel by stamping or pneumatically pressing it in the desired shape and size.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and " method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant's general inventive concept.