AU2005291399A1 - Plate for producing an electroluminescent number plate - Google Patents

Description

IN THE MATTER OF an Australian Application corresponding to PCT Application PCT/EP2005/010675 RWS Group Ltd, of Europa House, Marsham Way, Gerrards Cross, Buckinghamshire, England, hereby solemnly and sincerely declares that, to the best of its knowledge and belief, the following document, prepared by one of its translators competent in the art and conversant with the English and German languages, is a true and correct translation of the PCT Application filed under No. PCT/EP2005/010675. Date: 19 April 2007 E. A. LUCAS Director For and on behalf of RWS Group Ltd WO 2006/037607 PCT/EP2005/0 10 6 75 Plate for producing an electroluminescent number plate Technical field of the invention The present invention relates to a plate having an s inscription area and a border area, which lies outside of the inscription area, for producing an electroluminescent sign. The plate is in particular suitable for producing license plates for motor vehicles. The present invention also relates to a 10 process for producing an inscribed sign, in particular a license plate for motor vehicles, and to an electroluminescent sign, in particular a motor vehicle license plate, which can be produced in accordance with the process according to the invention. 15 Prior art of the invention Conventional license plates prescribed by the legislator for motor vehicles luminesce exclusively passively by means of a retroreflecting film. Such 20 license plates are conventionally produced from a so-called board, which may have a reflective surface. Alphanumeric characters which were allocated to the vehicle by the registration office are embossed in the board. The raised alphanumeric characters are then 25 coated with ink, with the result that the characters are visible against the background. For this purpose, a hot-rolling inking process is conventionally used in which the sign is processed at temperatures of approximately 2000C. If appropriate, a transparent 30 protective layer is also applied to the finished signs. Conventional production processes are therefore characterized by high mechanical and thermal loading of the board. 35 Furthermore, /electroluminescent coatings on motor vehicle signs are known which form an active light source (EP 1 262 373; DE 201 09 237). The German laid-open specification DE 198 27 477 Al has disclosed a license plate for a motor vehicle which provides, as Wo 2006/037607 - 2 - PCT/EP2005/010675 active illumination, a luminous film arrangement, which is arranged at least in the region of the license number, can be activated electrically and lies behind the license number and/or the surface of the sign. The 5 license plate proposed in the German utility model DE 200 22 563 develops the electroluminescent film arrangement further. Such an electroluminescent film arrangement does not allow conventional embossing, however. Instead, the alphanumeric characters are 10 applied by means of adhesive letters. DE 102 47 708 relates to a sign having an electroluminescent design which can be deformed or embossed. For this purpose, an electrically conductive 15 basic body is proposed which has a coating for forming a first electrode. A further coating with an electroluminescent pigmentation is applied to the first electrode, which further coating is in turn covered by an electrically conductive transparent layer so as to 20 form a second electrode. The design of the flat capacitor known from DE 102 47 708 is problematic. On the one hand, the layer structure needs to be applied in a complicated, multi-stage process, with the result that conventional boards cannot be used. In addition, 25 the electrodes extend over the entire inscription area, with the result that light from the electroluminescent coating is absorbed by the outer electrode layer, and the electrodes are damaged during the inscription process. 30 Electroluminescent films are known. DE 101 29 021 has disclosed the use of an electroluminescent film in a lighting device for vehicles. For example, the electroluminescent film is intended to be used in the 35 interior for illuminating control elements or in the exterior as vehicle boundary illumination, driving direction indicators, license plate lighting, rear spoiler brakelight illumination or rear spoiler foglight illumination. In order to produce the lighting WO 2006/037607 - 3 - PCT/EP2005/010675 device, a plastic injection-molded part is injected onto the film or the film is subsequently applied to the injection-molded part. The arrangement of the electroluminescent film in accordance with this 5 teaching does not result in mechanical loading of the film. On the basis of this prior art, the invention is based on the object of providing an electroluminescent plate 10 with which signs, in particular for motor vehicles, can be produced in accordance with the conventional embossing processes and hot-rolling inking processes, without the electroluminescence of the plate being impaired. 15 It is also the object of the invention to provide an electroluminescent plate with which signs can be produced in which the electroluminescence is not only used to illuminate the license plate but itself acts as 20 an information carrier. It is furthermore the object of the invention to provide a process with which electroluminescent signs, in particular vehicle license plates, can be produced 25 using conventional tools and procedures. It is furthermore the object of the invention to provide signs, in particular vehicle license plates, which can be operated in a simple manner and without an 30 additional current source on a vehicle. These and further objects are achieved in accordance with the claims. The present invention provides a plate having an inscription area and a border area, which 35 lies outside of the inscription- area, for producing an electroluminescent sign, the plate being characterized by (a) a board and WO 2006/037607 - 4 - PCT/EP2005/010675 (b) a film, which is provided with an electroluminescent coating, is provided on the board and extends at least partially over the inscription area and the border area, the f ilm 5 having metallic conductor tracks, which are electrically insulated from the board. The present invention also relates to a process for producing an inscribed sign, which comprises the 10 following steps: (a) providing an electroluminescent plate according to the invention; (b) cold-forming the plate in the inscription area with a pressing apparatus so as to form raised 15 areas for the inscription image for producing an embossed sign. Finally, the present invention also provides an electroluminescent sign, which can be produced in 20 accordance with the sign according to the invention. Preferred configurations are the subject matter of the dependent claims. 25 According to the invention, a motor vehicle, goods vehicle or motorcycle license plate having an electroluminescent film can be illuminated in such a way that the conventional technique for embossing license plates using rollers or similar tools can also 30 be used under the required action of heat when applying the combination of letters and numbers and the water mark (DIN standard embossing) . At the same time, all of the license plate-relevant features, such as the blue coloring of the EU license plates and their white 35 nationality identification (D, B, E, I etc.), the gold or gold/yellow coloring of the EU stars, the narrow, white border of the license plate, can luminesce independently and permanently, in each case individually and nevertheless as a whole in their WO 2006/037607 - 5 - PCT/EP2005/010675 predetermined, approved color spectrum by the connection with the vehicle electrical supply system, with a required voltage converter/inverter. 5 The present invention is based on the knowledge that a conventional flat capacitor design is disadvantageous for the purposes of producing an electroluminescent sign. The present invention is further based on the knowledge that electrodes which are in the form of 10 conductor tracks can be arranged such that neither destruction by the embossing process nor light absorption during the electroluminescence are possible and, nevertheless, a high luminous effect can be achieved. In addition, it has been found that it is 15 possible to dispense with complex electrical insulation of the board by using a film. Description of the preferred embodiments The plate according to the invention comprises an 20 inscription area and a border area. The inscription area is the area in which the plate can be deformed plastically by a conventional embossing process during inscription in accordance with the regulations. The border area is the area in which the plate cannot be 25 deformed plastically by a conventional embossing process during inscription in accordance with the regulations. The border area is along the outer contour of the plate up to a distance of a maximum of 25 mm. In particular, the border area extends between the 30 inscription and the upper/lower edge up to a distance of approximately 13 mm. The plate according to the invention comprises a board. The board may be a conventional aluminum sheet, which 35 is used for producing signs. The board may, however, also comprise any other material suitable for this purpose as long as it withstands the conditions of a conventional production process. it is therefore preferred for the board to comprise aluminum. In a WO 2006/037607 - 6 - PCT/EP2005/010675 further embodiment, in particular if the motor vehicle sign is designed such that it can be adhesively bonded on, a plate consisting of plastic may also be provided. This is then preferably a self-adhesive plate, which is 5 adhesively bonded onto the motor vehicle after the embossing process. The plate also comprises a film, which is provided with an electroluminescent coating and is provided on the 10 board. The electroluminescent coating may comprise a structure consisting of an electroluminescent layer, an electrically conductive layer on the visible side and an electrically conductive layer on the reverse. The coating contains one or more pigments which luminesce 15 when exposed to an electrical AC voltage field. In this case, the luminescence only occurs as long as the excitation owing to the AC voltage field is present. The electroluminescent layer can be applied by means of various processes, for example by being sprayed on, 20 painted on or by means of screenprinting processes. Electroluminescent printing pastes are generally produced on the basis of ZnS, CdS, ZnxCd..,S, compounds of the second and sixth group of the periodic table of the elements, which are generally doped with or 25 activated by Cu, Mn or Ag. Conventional colors are yellow, green, blue, red and white. Luminescent pigments can be micro-encapsulated and, with diameters of typically from 15 to 60 pm, can be admixed with screenprinting inks. 30 According to the invention, such electroluminescent pastes are applied to transparent plastic films, in particular polyester films, but also other non-hygroscopic films, by means of screenprinting or 35 other coating processes, such as painting or roller-coating, for example. A particularly preferred film is a polycarbonate film. It has been shown that when using a polycarbonate film ripping or splitting of the coated film during the embossing process can be wo 2006/037607 - 7 - PCT/EP2005/010675 avoided particularly effectively. In accordance with a further preferred embodiment, the film may be a film which has been precoated with a metallic coating. By way of example, mention is made of a silver-coated 5 polyester film, which is electrically conductive and can act as an electrode. The electroluminescent layer may have at least two areas which luminesce light of different colors. In 10 this way, the color-coded information on a motor vehicle sign can be read reliably even in poor light conditions. The luminescence of light of different colors is expediently achieved by different electroluminescent coatings being applied. 15 The electroluminescent film may have further layers which are used to protect the electroluminescent layer or the conductor tracks. These coatings may be electrically insulating or electrically conductive. The 20 selection of additional coatings is not particularly restricted as long as the effects and advantages of the present invention are not substantially impaired. In particular, the film may comprise further electrically conductive coatings (for example conventional ITO 25 coatings). It is preferred for the electrode to have as high degree of transparency as possible on the visible side in order to maximize the luminous efficiency. A paste coating based on ITO is preferably used. It is likewise preferred for a coating to be provided as the 30 reverse-side electrode, which coating may likewise be an ITO paste coating. The electroluminescent film preferably has a thickness in the range of from 0.2 to 3 mm, preferably in the 35 range of from 0.5 to 1.5 mm. The present invention provides a functional separation of the inscription area and the border area as regards the arrangement of the electrodes in the form of WO 2006/037607 - 8 - PCT/EP2005/010675 conductor tracks. For this purpose, the conductor tracks are preferably provided in the border area of the plate. In particular, the border area extends on the film along the outer contour of the board up to a 5 distance of 25 mm from the outer contour. It is likewise possible, even if not preferred, for the conductor tracks to protrude out of the border area into the inscription area. According to the invention, it is preferred for the conductor tracks to be present 10 on the same side of the electroluminescent layer. In particular, the conductor tracks may be present between the board and the electroluminescent coating. The conductor tracks can likewise be applied with the aid of a screenprinting technique. Then, electrical 15 insulation is provided which covers the conductor tracks. Once the film has been produced, it is preferably adhesively bonded to the board. It is therefore possible to develop a conventional board by adhesively bonding a film, which is designed according 20 to the invention, so as to form a plate according to the invention, which can be used in conventional embossing processes. In a preferred embodiment, the conductor tracks are 25 connected to an electronic component, which is provided on the film. The component may be a printed component. The conductor tracks preferably represent printed wiring. In a particularly preferred embodiment, the conductor tracks and possibly the component are 30 provided in the border area. In particular, a suitable electronic component is an inverter which is intended to provide a suitable AC voltage field, which brings about electroluminescence of the film via the conductor tracks, which act as electrodes. A further component 35 may be a photodiode, with which it is possible to control the switching-on of the electroluminescence if this is required by the external light conditions. The use of a photodiode makes it possible to optimize the life of the motor vehicle license plate since the WO 2006/037607 - 9 - PCT/EP2005/010675 electroluminescent layer is only subjected to an electromagnetic alternating field if required. In a further preferred embodiment, the film has two or 5 more printed chip inverters. In this way it is possible to supply various areas of the electroluminescent layer in each case using an inverter and the associated conductor tracks. This has the advantage that the particular features of the different electroluminescent 10 coatings can be matched to one another in terms of the luminous intensity and the life. The conductor tracks or the printed chip inverters which may be provided preferably have contact parts for 15 a power supply. The contact parts may preferably comprise a plug-type connection. An electronic memory, which can be written to or read from using an external device, can preferably be 20 provided on the film. in this way, information items can be stored on the sign which are conventionally arranged on inspection stickers or seals. Such identification means, which likewise need to be colored in accordance with the regulations, can be reproduced 25 with colored luminescence and can be read, written and set, corresponding to the next test time for the technical investigation, by means of IT, which is introduced into the colored electroluminescent film as well as possibly the chip inverters/voltage converters, 30 by means of a so-called scanner or read device, as is already conventional. This procedure can be repeated as often as required. The adhesive bonding which has been conventional to date is therefore not required. 35 Seals for federal states, administrative districts, towns or cities or other prescribed or desired seals can likewise be provided as described above, with the result that the desired or prescribed color spectrum is represented in luminous fashion in this case, too. The WO 2006/037607 - 10 - PCT/EP2005/010675 previous adhesive bonding of such seals would likewise be dispensed with. Likewise, the dating for the next special exhaust-gas investigation can be provided. 5 The plate preferably has a substantially rectangular outer contour for use for a motor vehicle. In particular, the plate has a width of from 10 to 25 cm. Preferably, the conductor tracks extend over substantially the entire length of the plate in order 10 to in this way achieve a uniform AC field over the entire length of the plate. The plate according to the invention can contain, in addition to the electroluminescent coating and the 15 conductor tracks, functional layers. In. a preferred embodiment, the film comprises a retroreflecting layer. In a particular embodiment, a large number of glass bodies, for example a suitable glass powder, will remain in the layer structure in order to impart 20 retroreflecting properties on the plate. In particular, a silver-coated polyester film with retroreflecting properties can therefore be provided. Also advantageous is a coating which protects the electroluminescent layer from UV radiation. Furthermore, it is possible to 25 provide a resistive layer in the border area which protects the conductor tracks from being affected mechanically, such as for example by impact from stones. In an alternative embodiment, a special cover can be provided on the frame of the sign which covers 30 the border area entirely or at least partially. In a further embodiment, a conventional retroreflecting film can be adhesively bonded to the plate according to the invention, with the result that retroreflecting 35 properties are imparted on the plate. Correspondingly, the retroreflecting film may have printed areas which represent further information on the decorative elements.

WO 2006/037607 - il - PCT/EP2005/010 67 5 Preferably at least one area of the electroluminescent layer luminesces whilst emitting white light, preferably with the co-ordinates x = 0.31 to 0.33 and y = 0.34 to 0.36. The brightness of this area is 5 preferably in the range of from 10 to 200 cd/r 2 , preferably 12 or 20 to 100 cd/m2. The electroluminescent layer preferably comprises areas which luminesce in different colors and reproduce 10 prescribed colored features of a license plate. In its special embodiment, the plate according to the invention comprises a board and a film, which is provided with an electroluminescent coating, is 15 provided on the board and extends at least partially over the inscription area and the border area, the film having metallic conductor tracks, which are electrically insulated from the board. The film provided with an electroluminescent coating comprises 20 an electroluminescent layer, which is provided between two electrically conductive electrode layers. The film provided with an electroluminescent coating is provided on the board using an adhesive layer. In addition, a retroreflecting film is provided on the film provided 25 with an electroluminescent coating in order to impart retroreflecting properties on the plate. The plate according to the invention can be produced in a simple manner by the film being applied to a 30 conventional board. In particular, the film can be adhesively bonded to the board using a suitable adhesive. The plate according to the invention can be used in 35 conventional processes for inscribing boards, in which the board is subjected to high mechanical loading or short-term thermal loading. It has been shown that, in the case of a functional separation of the inscription area, which comprises substantially only the WO 2006/037607 - 12 - PCT/EP2005/010675 electroluminescent coating but no conductor tracks, and the border area, which comprises, in addition to the electroluminescent coating, the conductor tracks for providing an AC field, the electroluminescence is not 5 impaired in any way if the plate according to the invention is inscribed in an embossing process and then colored in in a hot-inking process. It has further been shown that, when a plate according to the invention is embossed in a conventional embossing process so as to 10 form raised areas for the inscription, the luminosity of the remaining areas can surprisingly be increased. Correspondingly, the process according to the invention comprises the following steps: 15 (a) providing an electroluminescent plate according to the invention; (b) cold-forming the plate in the inscription area with a pressing apparatus so as to form raised areas for the inscription image for producing an 20 embossed sign. The cold-forming preferably takes place by means of deep-drawing. The process further comprises applying a film to the sign, the film being applied to the 25 embossed sign at elevated temperature using a conventional hot-embossing machine. Preferably, owing to the formation of raised areas, the luminosity of the remaining areas is increased. 30 The present invention further provides an electroluminescent sign which can be produced in accordance with the process according to the invention. The sign is preferably a motor vehicle license plate. 35 The electroluminescent sign can be mounted in a conventional holder for a license plate on a motor vehicle. The fixing can take place both by means of a screw connection at a plurality of points provided in WO 2006/037607 - 13 - PCT/EP2005/010675 the plate, with the result that the self-luminous, colored and white representation of the license number is retained, or by being fixed by means of being pushed/clamped into a conventional license plate holder 5 provided. It is possible to perforate a sign according to the invention in order to guide a fixing means, such as a screw, through the electroluminescent area without the 10 luminous effect being lost. Once the electroluminescent sign has been arranged on the vehicle, the conductor tracks need to be connected to a current source, which provides a power supply and 15 therefore an AC field. For this purpose, it is advantageous to connect the sign to the electrical supply system of the vehicle. Optionally, the voltage converter/inverter can be provided both on the vehicle at a suitable place and directly on the film by means 20 of chip inverter technology. This can also take place by means of the printing or production technique conventional to date for printing or producing EL films. The voltage converter/inverter means that all of the features which have previously been mentioned here 25 of the EU license plates, and others, with colored electroluminescence luminesce in their specific coloring in the uniform overall appearance of the electroluminescent license plates owing to the fact that they are connected to the vehicle electrical 30 supply system/electrical circuit. The sign according to the invention may be used as a vehicle license plate for all motor vehicles, heavy goods vehicles and motorcycles. The inverter can be matched so as to correspond to the different operating currents of the 35 respective vehicle classifications, for example 12 volts for motor vehicles, 12-24 volts for heavy goods vehicles and trucksters, 6-9 volts or else 12 volts for motorcycles depending on the design and year of construction.

WO 2006/037607 - 14 - PCT/EP2005/0-0675 The sign can be equipped with a conventional brightness sensor, which is provided on the board or the film, with the result that the self-luminous function for 5 improving the recognizability in darkness only sets in when it is required by the external influences, such as darkness when traveling through tunnels and the onset of darkness brought about by the time of day, for example. 10 The invention will now be described with reference to the drawing. Figure 1 shows a schematic plan view of a plate 1 15 according to the invention having an inscription area 101 and a border area 102, which lies outside of the inscription area. The board has a film which is provided with an electroluminescent coating. The film extends over the entire inscription area and the border 20 area. The film has metallic conductor tracks 31, 32, which are electrically insulated from the board. In addition, contact parts 51, 52 are provided with which the conductor tracks can be connected to the electrical supply system of the motor vehicle. 25 Figure 2 shows a schematic plan view of a further plate 1 according to the invention having an inscription area 101 and a border area 102. The film has metallic conductor tracks 31, 32, which are electrically 30 insulated from the board and are connected to an inverter 40, which is present in printed-on form on the film. The inverter 40 is supplied with current by the vehicle electrical supply system via contact parts 51, 52. 35 Figure 3 shows a schematic plan view of a further plate 1 according to the invention having an inscription area 101 and a border area 102. In contrast to the embodiment shown in figure 1, the plate has an WO 2006/037607 - 15 - PCT/EP2005/010675 electronic component EG with which the ambient brightness can be meas-ured and the ejectroluminescence controlled.

Claims (29)

1. A plate having an inscription area and a border area, which lies outside of the inscription area, for 5 producing an .electroluminescent sign, the plate being characterized by (a) a board and (b) a film, which is provided with an electroluminescent coating, is provided on the 10 board and extends at least partially over the inscription area and the border area, the film having metallic conductor tracks, which are electrically insulated from the board. 15

2. The plate as claimed in claim 1, characterized in that the electroluminescent layer has at least two areas which luminesce light of different colors.

3. The plate as claimed in claim I or 2, 20 characterized in that the conductor tracks are present on the same side of the electroluminescent layer.

4. The plate as claimed in one of the preceding claims, characterized in that the conductor tracks are 25 connected to an electronic component, which is provided on the film.

5. The plate as claimed in claim 4, characterized in that the component is a printed component. 30

6. The plate as claimed in one of the preceding claims, characterized in that the conductor tracks represent printed wiring. 35

7. The plate as claimed in one of the preceding claims, characterized in that the conductor tracks and possibly the component are provided in the border area. WO 2006/037607 - i- - PCT/EP2005/010 6 7 5

8. The plate as claimed in one of the preceding claims, characterized in that the conductor tracks are present in a border area, which extends on the film along the outer contour of the board up to a distance 5 of 25 mm from the outer contour.

9. The plate as claimed in one of the preceding claims for producing a motor vehicle license plate.

10 10. The plate as claimed in one of the preceding claims, characterized in that the board comprises aluminum.

11. - The plate as claimed in one of the preceding 15 claims, characterized in that the plate has a substantially rectangular outer contour.

12. The plate as claimed in claim 11, characterized in that the plate has a width of from 10 to 25 cm. 20

13. The plate as claimed in claim 12, characterized in that the conductor tracks extend over substantially the entire length of the plate. 25

14. The plate as claimed in one of the preceding claims, characterized in that the conductor tracks comprise contact parts for a power supply.

15. The plate as claimed in claim 14, characterized in 30 that the contact parts comprise a plug-type connection.

16. The plate as claimed in one of the preceding claims, characterized in that the film has a retroreflecting layer. 35

17. The plate as claimed in one of the preceding claims, characterized in that the film is adhesively bonded to the board. WO 2006/037607 - 18 - PCT/EP2005/010675

18. The plate as claimed in one of the preceding claims, characterized in that at least one area of the electroluminescent layer luminesces whilst emitting white light. 5

19. The plate as claimed in claim 18, characterized in that the electroluminescent layer comprises areas which luminesce in different colors and reproduce prescribed colored features of a license plate. 10

20. The plate as claimed in one of claims 13 to 19, characterized in that the film comprises an electronic memory, which can be written to or read from using an external device. 15

21. A process for producing an inscribed sign, which comprises the following steps: (a) providing an electroluminescent plate as claimed in one of the preceding claims; 20 (b) cold-forming the plate in the inscription area with a pressing apparatus so as to form raised areas for the inscription image. for producing an embossed sign. 25

22. The process as claimed in claim 21, the cold forming taking place by means of deep-drawing.

23. The process as claimed in claim 21 or 22, characterized in that the process further comprises 30 applying a film to the sign.

24. The process as claimed in claim 23, characterized in that the film is applied to the embossed sign at elevated temperature using a conventional hot-embossing 35 machine.

25. An electroluminescent sign, which can be produced in accordance with the process in claims 21 to 24. WO 2006/037607 - 19 - PCT/EP2005/010675

26. The sign as claimed in claim 25, which is a motor vehicle license plate.

27. The plate as claimed in one of claims 1 to 20, 5 characterized in that the film, which is provided with an electroluminescent coating, comprises at least two chip inverters.

28. The plate as claimed in claim 27, characterized in 10 that the chip inverters are printed on.

29. The process as claimed in one of claims 21 to 24, owing to the formation of raised areas, the luminosity of the remaining areas being increased.