GB2441013A

GB2441013A - A sign, in particular a vehicle number plate, incorporating an RFID device and an antenna for the RFID device.

Info

Publication number: GB2441013A
Application number: GB0616524A
Authority: GB
Inventors: Peter Curtis
Original assignee: CURTIS CONSULTING Ltd
Current assignee: CURTIS CONSULTING Ltd
Priority date: 2006-08-19
Filing date: 2006-08-19
Publication date: 2008-02-20
Also published as: GB0616524D0

Abstract

A sign, in particular a vehicle number plate, comprises an RFID device and a metallic base layer shaped as an antenna 41, 51 for the RFID device. The metallic base layer is preferably part of a laminate layer which forms a retroreflective layer for the sign. The metallic layer is preferably kiss cut or laser cut to form the antenna shape. The antenna is ideally formed as half-wavelength dipole antenna. A plurality of contact areas may be provided to allow for different RFID device orientations.

Description

I

A Sign The present invention relates to signs and more particularly to signs such as vehicle number plates which incorporate embedded radio frequency tags or emitters (RFI) and devices.

Signs are used in a wide number of situations ranging from simple identifiers as to direction or to provide information through registration plates and signage for motor vehicles or other identifiers for machines. A basic sign comprises an alpha numeric word or phrase and/or a pictorial representation of the information to be advertised. More recently the typical graphic signage identifiers have been supplemented with radio frequency emitters (RFI) as identifiers to be machine readable as well as provide a means of checking correspondence between the graphical indicators for authenticity and the information available from the RFI device.

RFI devices do not generally incorporate batteries which may become depleted but depend upon back emf in order to drive an emitter providing the information via a radio signal. It such circumstances it will be appreciated that electro magnetic induction from a stimulator transceiver is required.

Unfortunately, with regard to some signage such as vehicle number plates a metallic base is typically used to act as a reflector. These metallic bases can act as Faraday shields and prevent either appropriate electromagnetic induction for back emf or prevent return signal transmission efficiency and so reduce the effective range for the RFI device.

In accordance with certain aspects of the present invention there is provided a sign comprising a radio frequency emitter (RFI) and a metallic base, the metallic base shaped to provide an aerial for the radio frequency emitter.

Typically, the sign comprises a vehicle number plate.

Normally, the metallic base comprises a reflector for the sign.

Possibly, the metallic base is part of a laminate layer for the sign.

Generally, the metallic base is formed by glass beads with a metalhc backer foil.

Possibly, the metallic base is kiss cut or laser cut.

Possibly, the aerial is configured as a spiral or zig zag. Additionally, the aerial is configured to provide a dipole. Generally, the dipole has a length in the order of half the wavelength of the expected radio frequency for the signal.

Possibly, the aerial provides a plurality of contact areas for different RFI orientations.

Embodiments of certain aspects of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:-Fig. 1 is a schematic plan view of a sign; Fig. 2 is a schematic side view of the sign depicted in Fig. 1; Fig. 3 is a plan view of a sign in accordance with certain aspects of the present invention; and, Fig. 4 is a schematic plan view of a sign in accordance with certain aspects of the present invention.

Figs. 1 and 2 illustrate a typical sign arrangement 1 in which a graphic identifier is schematically shown in area 2 with a radio frequency emitter device or tag 3 associated with the sign 1. The sign I may typically take the form of a vehicle registration plate and therefore the graphic identifier 2 will comprise alpha numeric numbers. The RFI device 3 will typically include confirmatory information with respect to the alpha numeric indicators in the graphic identifier 2 as well as other information.

Generally the sign 1 comprises a laminate formed from plastic materials. Thus, as shown in Fig. 2 a film provides the graphic identifier 2 sandwiched between laminates 4, 5. In such circumstances the sign I is relatively robust and weather resistant. The film upon which the alpha numeric details to form the graphic identifier are provided will generally be presented appropriately. The RFI device 3 will be located in a pocket or otherwise secured within or between the laminates 4, 5 of the sign 1.

In order to improve visibility with respect to the graphic identifiers presented by the sign 1 it is common to provide a reflective backer. This reflective backer will typically take the form of a metal and more particularly a multitude of micro glass beads associated with a metal foil backer.

Unfortunately, metal foil if located over the RFI device 3 will tend to mask both radio frequency emissions for information exchange as well as induced emf to power the RFI device.

As indicated above this metallic layer is generally relatively thin and extends behind the film upon which the alpha numeric characters are utilised in order to create the graphic identifier 2. In such circumstances the metallic base can be cut and shaped to a desired form using laser cutting or a kiss press cutting process such that an isolated shape can be created from the metallic base.

in accordance with certain aspects of the present invention an aerial for the RFI device is formed by appropriate cutting and shaping of the metallic base to a desired format.

As indicated RFI devices depend upon induced emf to activate generally relatively small integrated circuit devices. Typically the aerial is provided by a number of concentric etched tracks with the processor secured across these tracks. In accordance with certain aspects of the present invention, the whole of the metallic backer used previously as a reflector to enhance definition with regard to the graphic identifier 2 is also used to provide an aerial for transmission of the electro magnetic signals as well as an inductor to generate electrical power to drive the processors of the radio frequency identifier (RFI).

The actual shape formed in the metallic base to create an aerial will be determined by operational requirements. It will be understood that aerials can be uni directional or multi directional in terms of their dipole distribution, In order to create the aerial a particular pattern will be chosen and cut either by a laser cutting process or by a press kiss cut process with a die-cutter, It will be understood that normally the aerial will be cut such that there is an electrical isolation of the aerial from the remainder of the metallic base. In such circumstances the remainder of the metallic base may be removed or left in-situ, In any event the cut aerial as indicated will act to allow transmission of the radio signal as well as for induction to generate emf for electrical powering of the RFI device.

Figs. 3 and 4 illustrate respectively potential aerial shapes in accordance with aspect of the present invention. The depictions in Figs. 3 and 4 are schematic and it will be appreciated that the graphic identifier part of the sign has been removed.

In Fig. 3 a simple dipole aerial 31 is created. This aerial 31 is laser or kiss cut from a metallic base 32 with a pocket 33 to accept an RFI device.

Generally as indicated above, the aerial 31 is isolated from the remainder of the metallic base 32 with a gap 34 in order that there is no electrical conductive connection between the aerial 31 and the remainder of the metallic base 32. Alternatively, the remainder of the metallic base can be removed by an appropriate etching process or otherwise to leave only the aerial 31.

An RFI device is secured in the pocket 33 with electrical contacts to the aerial 31 to act appropriately. The aerial 31 is shaped in the embodiment depicted in Fig. 3 to act as a dipole. The aerial will therefore be directional in terms of the radio wave transmission which may have limitations with regard to operational performance.

Fig. 4 illustrates respectively two alternative aerial format in sections A and B. In section A an aerial 41 is defined which has a wavy shape. This aerial 41 is again laser cut or kiss cut from a metallic base 42 with a gap 44 to isolate the aerial 41.

In portion B an aerial 51 has a branched format again, cut by a laser or kiss cut process with a gap 54 between the aerial 51 and a metallic base 52.

It will be appreciated that the aerial formations 41, 51 shown in Fig. 4 will be of a less uni directional edge than that depicted in Fig. 3 and therefore transmit radio signals which may be picked up over a wider hemisphere by a receiver device.

As indicated above, the present sign has particular applicability with regard to vehicle number plates. These number plates generally incorporate a metallic base in order to emphasise under headlights the readability of the graphic identifiers in the form of alpha numeric symbols. In such circumstances during the manufacturing process for the number plate an aerial in accordance with the aspects of the invention described above may be cut and shaped as appropriate. This aerial as depicted in Figs. 3 and 4 may be a single linear dipole or spiral or wave or zig zag/saw shape or branched.

The radio frequency identifier will be incorporated within the sign in order that it is in electrical contact with the aerial created by the metallic base in order to act appropriately. It will be understood that normally a pocket may be provided to receive the RFI device. However, these devices may be in the form of a patch and therefore have limited thickness enabling this patch to be very thin so that the RFI device can sit with the film upon which the alpha numeric symbols are located in order to provide the graphic identifier. In such circumstances if a pre assembly shaping of the metallic base is provided to create an aerial it will be understood that these aerials may incorporate a number of contact patches for coupling with an overlaid RFI patch to achieve an electrical connection and operability. In such circumstances the same base preformed sign format with an aerial in accordance with aspects of the present invention may be utilised with different RFI device configurations.

The patches for electrical coupling with the aerial will take the form of electrical terminals which can readily be associated with reciprocal electrical terminals in the RFI device.

It will also be understood that the aerials may be formed by etching away the metallic base in order to leave the aerial behind. However, such chemical processing may degrade the base laminates or otherwise of the sign reducing its applicability. Furthermore it will be understood that an etching process may be time consuming whereas isolating the aerial through a cut whether it be by laser or a kiss die cut would be more rapid.

By the use of the metallic base of a sign it will be appreciated that the aerial size is increased as well as the area of conductance for emf effects to achieve electrical powering of the RFI device. In such circumstances the effective range of the RFI device may be increased allowing more effective use of RFI devices with moving vehicles. Furthermore, in view of the increased response power any shift in such moving vehicles with respect to their RFI response may be reasonably accommodated.

To emphasise the aerials in accordance with aspects of the present invention only a limited area of the metallic base has been used to define aerials in Figs. 3 and 4. It will be understood that in a more practical unit an aerial may be designed to utilise a greater proportion of the area of the metallic base to again increase the operational performance of the RFI in combination with the aerial.

Alterations and modifications to the present invention will be appreciated by those skilled in the art. Thus, in addition to use with respect to vehIcle registration plates, it will be understood that other signage may utilise RFI devices and that signage may incorporate a metallic base which can be utilised as an aerial to the benefit of the RFI device rather than a potential mask. In such circumstances back reflector road signage or emergency signage within a building may incorporate an RFI device and the metallic base normally utilised to act by back reflection to enhance graphic identifiers may be cut appropriately to create aerials to emphasise the RFI performance.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. A sign comprising a radio frequency emitter (RFI) and a

metallic base, the metallic base shaped to provide an aerial for the radio frequency emitter.
2. A sign as claimed in claim 1 wherein the sign comprises a vehicle number plate.
3 A sign as claimed in claim 1 or claim 2 wherein the metallic base comprises a reflector for the sign
4. A sign as claimed in any of claims 1 to 3 wherein the metallic base is part of a laminate layer for the sign.
5 A sign as claimed in any proceeding claim wherein the metallic base is formed by glass beads with a metallic backer foil : .
6 A sign as claimed in any proceeding claim wherein the metallic base is kiss cut or laser cut.
7. A sign as claimed in any proceeding claim wherein the aerial is configured as a spiral or zig zag. * S

*:*.
8. A Sign as claimed in any proceeding claim wherein the aerial is configured to provide a dipole
9. A sign as claimed in claim 8 wherein the dipole has a length in the order of half the wavelength of the expected radio frequency for the signal.

10 A sign as claimed in any proceeding claim the aerial provides a plurality of contact areas for different RFI orientations.

11. A sign substantially as hereinbefore disclosed with reference to the accompanying drawings.

12. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims, I. * * * *** **** * S S'S. * *5 * S * * S* * S S...

S * SS I.