GB2404167A

GB2404167A - Manufacturing identification plates

Info

Publication number: GB2404167A
Application number: GB0317348A
Authority: GB
Inventors: Michael Cordell; Richard Ivor Taffinder
Original assignee: Hills Numberplates Ltd
Current assignee: Hills Numberplates Ltd
Priority date: 2003-07-24
Filing date: 2003-07-24
Publication date: 2005-01-26
Anticipated expiration: 2023-07-24
Also published as: GB2404167B; GB0317348D0

Abstract

An identification plate is manufactured by <UL ST=" Ò "> <LI> forming a length of plastics material; <LI>attaching a retro-reflective sheet material to a major surface of the plastics material; <LI>cutting and/or trimming the plastics material having a retro-reflective major surface to form a substrate-sized blank; and <LI>securing a transparent sheet material to the retro-reflective surface. </UL> The transparent sheet material may carry indicia which are preferably in contact with the retro-reflective sheet material.

Description

Aqent's Ret: P04037GB

IDENTIFICATION PLATES

This invention relates to methods of manufacturing identification plates, specifically but not exclusively, to plates which indicate the provenance of an object to which they are attached. Such plates are conventionally termed licence or number plates when attached to a motor vehicle.

In our co-pending British patent application No. 0213896.4 (GB 2376437) we disclose methods of manufacturing identification plates, one such method comprises: À advancing a transparent sheet material having an opaque material in contact with a first major surface thereof to a printing station; À printing indicia in reverse on to a second major surface of the sheet material; À securing the printed sheet material to a rigid plastics substrate having a retro-reflective surface such that the printed surface is in contact with, or at least adjacent to, the retro-reflective surface.

In that application, there are also disclosed ancillary methods for forming a substrate with a retro-reflective surface. One such described method comprises moulding or extruding plastics materials, for example acrylonitrile butadiene styrene (ABS), and then cutting the plastics material to size. A retro-reflective sheet material is then laminated to the substrate to provide a surface with a retro-reflective characteristic.

In the above-identified process, plastics material is (usually) extruded in up to 2m wide lengths. Soon after extrusion, a cover layer or release liner is applied to the surface of the plastics extrusion for protection. The wide sheet of plastics material is then cut by a saw and trimmed (usually in two separate operations) to form a substrate-sized blank. The trimming step will usually provide the blank with radiused corners and a slight bevel at the edge which is why the cutting and trimming steps are separate. The retro-reflective sheet material must also be cut to substrate-sized lengths and the two laminated together. Clearly, it is imperative that the blank and retro-reflective sheet material are in very accurate registration to prevent or reduce waste.

The applicants have now discovered that the process can be greatly simplified by reducing the number of steps required to form an identification plate.

Indeed, it is an object of this invention to provide a method of fabricating an identification plate which is quicker, cheaper, more efficient and convenient than has previously been achievable. It is a further object of the invention to reduce waste in the manufacture of identification plates.

Accordingly, a first aspect of the invention provides a method of manufacture of an identification plate, the method comprising: À forming a length of plastics material; À attaching a retro-reflective sheet material to a major surface of the plastics material; À cutting and/or trimming the plastics material having a retro-reflective major surface to form a substrate-sized blank; and À securing a transparent sheet material to the retro-reflective surface.

Preferably, the length of plastics material is formed by extruding or moulding! plastics.

The length of plastics material is preferably formed with a size such that a plurality of substrate-sized blanks can be cut and/or trimmed therefrom. In a preferred embodiment, the length of plastics material is 2 metros wide and of any convenient length. I When vehicle identification plates are to be fabricated, the finished plates are 520 x 111 mm and of a thickness sufficient to impart the plate with the necessary bend strength and impact resistance. Conventionally, as described above, the 2m wide plastics sheet is cut with a saw to about 522-523 x 113 mm. The blanks are then passed to a trimming machine which cuts the blanks to the appropriate size, bevels the edges and provides radiused corners. Therefore, about fifteen blanks can be formed across a 1.6 m wide sheet.

Accordingly, when operating the current invention and when forming a 1.6m wide plastics length, retro-reflective sheet material is, say, laminated over the entire sheet and the so-formed laminate may be cut to form fifteen blanks with a retro reflective major surface.

If operating the method on a smaller scale, the length of plastics may be formed, say, 113 mm wide and then have a retro-reflective sheet material laminated thereto, a single cut can then be made to separate the length into, say, 522 mm lengths and those lengths may then be passed to a trimmer for final shaping.

Clearly, any width of plastics length may be used, the above two widths are illustrative only.

In one embodiment, the plastics length is extruded or moulded and the retro- reflective sheet material is secured thereto by lamination. In a second embodiment, the plastics length is extruded and the retro-reflective sheet material, preferably carrying an adhesive on the surface which is to contact the surface of plastics length, is secured to the plastics length by being brought into contact with the plastics length as the plastics length is forced through the extrusion head.

A further surprising advantage when operating the method is that when the retro-reflective sheet material is secured to the length of plastics when it is emerging or has just emerged from its forming step, any residual heat retained within the plastics aids the securing of the retroreflective sheet material thereto when a suitable (thermally activated) adhesive is used, thereby providing a more secure bond between plastics length and retro-reflective sheet material.

Preferably, the plastics material is formed from ABS or coloured acrylic, although other plastics materials which impart a necessary impact resistance and/or bend strength may be used.

Suitable retro-reflective sheet materials are either coated or non-coated. In such coated sheet materials, a thin acrylic layer is applied to the beaded surface, thereby providing those reflective particles with a lens and imbuing the sheet material with retro-reflective characteristics. In non-coated retro-reflective sheet materials the surface is only provided with a retro-reflective character once a lens has been applied to it. With such non-coated retro-reflective sheet materials, when used in the methods disclosed above, the lens is provided by the transparent material and it is only once this material has been applied to the retroreflective material that the whole 'sandwich' acts retro-reflectively. Whilst non-coated retro reflective materials are typically less expensive than the coated ones and for that reason may be preferred, it is possible to use either in the method disclosed herein.

The retro-reflective sheet material may be engineer-grade, diamond-grade or high intensity grade, all sold by 3M of St. Pauls, Minnesota, USA. Of course, any other suitable retro-reflective material may be used. The above-mentioned retro- reflective sheet materials are available in up to 1.6m wide lengths.

In a preferred embodiment, an adhesive is laminated to the retroreflective sheet material once it has been secured, for example laminated, to the plastics length, the adhesive being covered by a protective layer, and the whole sandwich or laminate then being cut and/or trimmed.

In a most preferred embodiment, the retro-reflective sheet material carries a layer of adhesive on both major surfaces thereof, one of those major surfaces being protected by a protective layer, say a release liner. In this case, the non-protected major surface is secured, for example laminated, to the plastics length. The whole sandwich or laminate is then cut and/or trimmed, thereby providing a blank which is ready to have a transparent sheet material laminated thereto, once the protective layer has been removed.

In a further embodiment, the retro-reflective sheet material may be pre printed or pre-formed with indicia and/or other markings (i.e. the indicia and/or other markings are printed onto or formed on the retro- reflective sheet material before it is secured to the plastics length). Such indicia and/or other markings may be, inter alla, one or more of a euro flag, a border, a manufacturer identifier, a barcode and so on.

The cutting and/or trimming may be optically controlled by reference to indicia and/or markings on the retro-reflective or may be mechanically controlled by reference to a pre-programmed or pre-arranged cutting sequence.

The transparent sheet material is preferably chosen from one of polyethylene, polypropylene, polyester, polyvinyl chloride. Other polymers and co- polymers may also be used, as will be appreciated by the skilled addressee.

The transparent sheet is preferably less than 150 Bum thick, more preferably less than 1 00'um thick.

Preferably, the transparent sheet material has primary indicia and/or other markings printed onto a major surface thereof, the indicia and/or other markings being in contact with, or at least adjacent to, the retroreflective surface once the 5sheet is secured to the retro-reflective surface.

In a second embodiment, primary indicia are/or other markings are printed onto the retro-reflective surface of the blank and the transparent sheet material is then secured thereto.

If the identification plate is to be used as a vehicle licence plate, the primary indicia will be indicative of the vehicle to which the plate is to be attached.

Preferably the printing of indicia takes place in accordance with our co 15pending British patent application No. 0213896.4, the entire of which is herein incorporated by reference.

Thus, a more specific aspect of the invention provides a method of manufacturing an identification plate, the method comprising: 20À advancing a substrate-sized length of transparent sheet material to a printing station, the sheet material having an opaque substance in contact with one major surface thereof; À optically sensing passage of the leading edge of the substrate-sized length of transparent sheet material by attenuation of an optical beam by 25the opaque substance; À printing indicia in reverse on the other major surface of the sheet material; À securing the printed transparent sheet material to a relatively thick rigid plastics substrate having a retro-reflective surface such that the printed surface is in contact with, or at least adjacent to, the retroreflective surface; and À removing the opaque material from the transparent sheet material, À wherein the plastics substrate having a retro-reflective surface is formed by forming a length of plastics material, securing a retro- reflective sheet material to a major surface thereof and cutting and/or trimming the plastics length to form a substrate.

The transparent sheet material may be supplied on a roll, or as individual substrate-sized lengths. If the transparent sheet material is supplied on a roll, it may be shaped as a repeating pattern, each repeat thereof corresponding to a substrate sized length.

The opaque material may be a release sheet, in one embodiment a paper release sheet. Alternatively, the opaque material may be a plastics release sheet, such as a polypropylene sheet. The release sheet may be provided with a pressure sensitive emulsion adhesive layer, the transparent material may have a silicone layer applied thereto, the silicone layer which is contacted by the adhesive layer of the release sheet facilitates separation of the release sheet and sheet material. The silicone layer and adhesive layer allow the release sheet and sheet material two to be releasably adhered, such that the release sheet may be re-applied to the transparent material.

Said printing means may be arranged to print over some, most, or all of the transparent sheet material.

The transparent sheet material may have secondary and/or other information printed on the other major surface prior to being advanced to the printing station.

The printing, on the transparent sheet material, of any secondary and/or other information may be completed 'off-line', which is to say that information may be printed and the transparent sheet material stored or held for future use. The printing of secondary and/or other indicia may be completed immediately before or after printing of the primary indicia.

Said printing means may preferably comprise a thermal mass transfer printer, laser printer or an ink jet printer.

In order that the invention may be more fully understood, it will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a flow chart showing a prior art method; Figure 2 is a flow chart showing the method of the invention; Figure 3 is a schematic representation of a part of the method of the invention; Figure 4 is a schematic representation of a second embodiment of part of the invention, and Figure 5 is a schematic representation of the formation of a vehicle identification plate using a blank formed using the method of the invention.

Referring firstly to Figure 1 there is shown a flow chart exemplifying the prior art, as stated in our co-pending British patent application no. 0213896.4. The flow chart identifies the seven steps 1-7 necessary to form a vehicle licence plate but ignoring the steps relating to the printing of the identifying vehicle indicia onto the transparent sheet material.

Referring now to Figure 2, it is readily seen that the inventive method of the current application requires only five steps 10-14 to fabricate a vehicle licence plate.

As will be appreciated by the skilled addressee, the method of the invention will not only be quicker and more convenient that the prior art method due to the fewer number of steps but it will also result in less waste. For example, step 6 of the prior art method requires that a substrate-sized length of retro-reflective material is laminated to a blank to form a substrate. If the blank and the retro-reflective sheet are not the same size there will be a further trimming step required, or the so-formed blank will have to be disposed of. Further, if there is a less than perfect registration during the lamination step 6 the substrate will have to be disposed of or trimmed, both of which steps cost time and money.

By contrast, because the retro-reflective material is laminated in step 11 prior to the cutting of the plastics length, there will never be a problem about registration or the blank and retro-reflective being different sizes. Therefore, there will be a reduction in the amount of waste blanks.

In step 11, when a thermally activated adhesive is used on the retroreflective sheet material, any residual heat in the plastics length helps to improve the strength of the bond between retro-reflective and plastics material or, at least, reduces the extra heat which would usually have to be applied during lamination.

There is a further, clear saving in as much as the protective cover layer of step 2 need not be applied.

A further advantage which has been found is that the trimming machine, when trimming the individual lengths, forces the retro-reflective sheet material into the plastics, forming a better bond at the periphery of the blank than is otherwise

found in prior art methods.

Figure 3 shows part of an extruded sheet 20 formed of black or otherwise coloured acrylic having a retro-reflective sheet material 21 laminated to a major surface of the extruded sheet. Shown on the sheet material 21 are nominal cut lines 22 which a saw (not shown) will run along to provide individual lengths 23 of 523 x I 113 mm. The individual lengths 23 will then be passed to a trimming machine (not shown) which will cut the individual lengths to 520 x 111 mm, will bevel the edges of the blank and radius the corners. These operations are pre-programmed or pre- arranged and are carried out automatically.

Figure 4 shows a part of a sheet of extruded plastics material 25 having a retro-reflective sheet material 26 laminated to a major surface thereof. The sheet material has nominal cut lines 27 which are not visible. The retro-reflective sheet material 26 has been pre-printed or formed with a series of 'Euro' flags 28 and a series of borders 29. The nominal cut lines 27 thereby define individual lengths to be trimmed to form blanks.

As the plastics sheet 25 passes a saw (not shown), the saw optically recognises the position of the Euro flag 28 and/or the border 29 and cuts an individual length according to the location of that flag 28 and/or border 29.

Therefore, if the retro-reflective sheet material 26 is laminated to the extruded plastics sheet 25 so that their principal axes are not parallel, the saw will still cut an individual length which can be trimmed to form a blank.

The individual lengths are passed to a trimming machine (not shown) which, as above, provides a final blank to which a printed transparent sheet may be laminated, as per our British patent application no 0213896.4.

As will be appreciated, optical or mechanical control may be utilised. The retro-reflective surface may be provided with guide lines at the intended corner of a blank for control of the saw and/or trimming machine.

In a further embodiment, the retro-reflective sheet material 21 may have an adhesive laminated thereto prior to cutting, the adhesive may be protected by a release layer. Thus the so-formed blanks after cutting and/or trimming will be a laminate of extruded plastics sheet 20, retroreflective sheet 21, adhesive and release layer. The so-formed blank is then ready for lamination to a printed transparent sheet material to thereby form a vehicle licence plate.

Indeed, referring to Figure 5 there is shown a, a length of medium 51 to be printed upon, comprising a length of transparent film 52 having an opaque release liner 53 in contact with one major surface thereof, is advanced in the direction of arrow A. Among other advantages, which will become apparent, the release liner 53 provides the length of film 52 with some rigidity, making it easier to handle. The transparent film 52 is preferably polyester film with a thickness of about 50,um. The opaque release liner 53 is preferably paper or polypropylene with a thickness of about 100,um.

The release liner 53 has a pressure sensitive adhesive emulsion layer applied thereto, that layer is typically 10 to 15,um thick. The transparent polyester film 52 has a layer of silicone applied thereto, which is typically about 3 to 5,um thick. . The silicone layer is in contact with the adhesive layer. The silicone layer prevents complete adhesion between the adhesive layer and transparent film 52, and allows the release liner 53 to be removed and reapplied to the transparent film 52. This allows inspection of the completed plate and re-application of the release liner 53 to protect the surface during transit to a point of use or storage.

The printable medium 51 is brought to a printer 55 which is a thermal transfer printer having a printing head 56 and a ribbon 57. Mounted either externally or internally of the printer 55 is an optical sensing device 58, comprising an optical beam generator 59 and a detector 60, located on opposite sides of the path of travel of the medium 51.

The output of the optical beam generator 59 is detected by the detector 60 in the usual way so that any non-optically transparent medium which interrupts the beam causes a reduction in the signal detected by the detector 60. The signal detected by the detector 60 can be used to control operation of the printing head 56.

For example, if the detected signal rapidly decreases, due to attenuation of the beam, the reduction is detected by signal processing means 61, such as a computer, which, in turn, controls the printing head 56 to print on the film 52. Clearly, the speed at which the medium 51 is conveyed should be monitored and/or controlled. Monitoring the time between maximum signals and the speed at which the medium 51 is conveyed allows accurate control of the location of so-printed indicia.

As the printable medium 51 passes through the optical beam, the signal detected by the detector 60'decreaces, due to the presence of the opaque release liner 53. The signal processing means 61 responds to the reduction of detected signal to control the printing head 56 to start and finish printing the desired indicia on the transparent film 52, in reverse. That is to say that the printer 55 prints on the underside, as shown in Figure 5, of the transparent film 52. The opaque liner 53, which has a rougher surface than the transparent sheet material 52 and adds extra effective thickness, enables the rollers of the printer to both grip the medium 51 and keep it in accurate registration and thereby print onto the transparent film 52.

A computer, which may or may not be the same as said signal processing means 61, holds a store of the indicia desired to be printed onto the medium 51. The information is transmitted to the printer 55 which preferably arranges the formatting of the desired indicia. An eminently suitable and preferred printer is a QLS-4100 series, supplied by Astromed Incorporated of Rhode Island, USA. The print rate of such a printer can be as high as 20.4 cm per second, but is more typically operated at 7. 6 cm per second. Therefore, using such a printer with optical control, up to 1200 standard British vehicle licence plates (52.1 x 11.1 cm) per hour can be produced automatically.

The resulting printed medium 65 is advanced to a lamination station 67. A length of substrate 23 formed from extruded acrylic with a retroreflective surface 21 formed in accordance with the above-described method, is also advanced to the lamination station 67. The substrate 23 is typically from 2.5 to 3.8 mm thick, preferably 3.2 mm thick. The substrate has a release sheet 24 covering a pressure sensitive adhesive layer (not shown). The adhesive layer and release sheet 24 were applied to the substrate prior to the cutting of a plastics length. The release sheet 24 is removed as the substrate 23 is advanced to the lamination station 67.

The printed medium 65, comprising transparent film 52 and opaque release liner 53, and the length of substrate 23 are shown as being rectangular, with right angle corners. Other shaped corners are possible, for example, each of the components 52, 53, 23 may have curved or radiused corners. Preferably, the substrate 23 is formed with a bevelled edge formed by the trimming machine.

The so-formed laminated composite 70 is advanced to a further point where the opaque releasable liner 53 is removed from the transparent film 52, thereby providing a finished identification plate 80. Removal of the release liner 53 may be carried out prior to or subsequent to installation of the plate 70 on a vehicle so that the surface of the plate 70 is protected during transit. The silicone layer will be removed by the action of the elements, precipitation, wind and so on.

The transparent film 52 acts as a lens for a non-coated retro-reflective surface 21 providing it with a retro-reflective characteristic. As the lens for the retro- reflective surface 21 is simply a thin film 52 rather than a thick, transparent substrate, as is the case in certain prior art techniques, it is found that the indicia are clearer and the plate 80 has a higher retro- reflectivity (due to the much shorter path length for impinging and reflected light), both of which are desiderata of vehicle Iicence plates. When coated retro-reflective surfaces 21 are utilised, the thin film 52 does not impair the retro-reflective character of the surface 21.

10The above description has concentrated on what may be called individual or single-shot' printing. However, what may be termed continuous, 'batch' or web printing may also be used, wherein a length of printable medium comprising a web of transparent film provided with a releasable backing layer is delineated into substrate-sized lengths by transverse perforations, as shown in Figure 4 of our co 15pending British patent application no. 0213896.4. The individual lengths are shaped with rounded corners.

The plastics sheet 20 may be moulded and the retro-reflective sheet material 21 laminated or otherwise applied thereto. If the plastics length is extruded, the retro-reflective sheet material, preferably carrying an adhesive on that surface which is to be secured to the plastics sheet, may be forced through the extrusion head at the same time, thereby obviating the requirement for a lamination step.

The methods disclosed herein can be used to manufacture vehicle licence plates as well as other signage - warning signs, direction signs, roomuse indicators and so on.

Claims

Claims 1. A method of manufacturing an identification plate, the method

comprising: l À forming a length of plastics material; À attaching a retro-reflective sheet material to a major surface of the plastics material; ,' À cutting and/or trimming the plastics material having a retro-reflective major surface to form a substrate-sized blank; and À securing a transparent sheet material to the retro-reflective surface. t
2. A method according to Claim 1, comprising forming the length of plastics I material by extruding or moulding plastics.
3. A method according to Claim 1 or 2, comprising forming the length of plastics 3 material in a size such that a plurality of substrate-sized blanks can be cut therefrom.
4. A method according to Claim 1, 2 or 3, comprising forming the length of plastics material to have a width of up to about 2 metres and of any convenient length.
5. A method according to Claim 4, comprising cutting the length of plastics material by sawing to form a blank having dimensions of about 522-523 x 113mm. i
6. A method according to Claim 4 or 5, comprising trimming the plastics material or blank to form a substrate-sized blank, having dimensions of about 520x111 mm.
7. A method according to any preceding Claim, comprising laminating the retro reflective sheet material to the plastics length.
8. A method according to any of Claims 1 to 6, comprising securing the retro reflective material to the plastics length by bringing retroreflective sheet material into contact with plastics material as the plastics material is forced through an extrusion head.
9. A method according to any preceding Claim, comprising printing indicia onto one of the retro-reflective sheet material or the transparent sheet material.
10. A method according to Claim 9, comprising printing indicia, in reverse, onto the transparent sheet material and securing the transparent sheet material to the retro-reflective surface of the substrate-sized blank such that the indicia are in contact with, or at least adjacent to, the retro-reflective sheet material.
11. A method according to any preceding Claim, comprising providing markings on the retro-reflective sheet material prior to cutting the plastics length.
12.A method according to Claim 10, comprising controlling the cutting and/or trimming of the plastics length by reference to the markings on the retro- reflective sheet material.
13. A method of forming an identification plate for a vehicle, the method composing: À advancing a substrate-sized length of transparent sheet material to a printing station, the sheet material having an opaque release liner in contact with one major surface thereof; À optically sensing passage of the leading edge of the substrate-sized length of transparent sheet material by attenuation of an optical beam by the opaque release liner; À printing indicia in reverse on the other major surface of the sheet material; À securing the printed transparent sheet material to a rigid plastics substrate having a retro-reflective surface such that the printed surface is in contact with, or at least adjacent to, the retro-reflective surface; and À removing the opaque material from the transparent sheet material, À wherein the plastics substrate having a retro-reflective surface is formed by forming a length of plastics material, securing a retro- reflective sheet material to a major surface thereof and cutting and/or trimming the plastics length to form a substrate.