GB2340982A

GB2340982A - Vehicle Registration Plate

Info

Publication number: GB2340982A
Application number: GB9818721A
Authority: GB
Inventors: Bernard Arthur Henshaw
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-28
Filing date: 1998-08-28
Publication date: 2000-03-01
Also published as: GB9818721D0

Abstract

A vehicle registration plate 10 comprising a panel member 12 of electroluminescent (EL) material. The EL panel 12 has mask members 14 provided on one face. These mask the output of the panel 12 over selected areas, to form a plurality of alphanumeric characters. An electrical power supply 16 is electrically connected to the EL panel 12, for applying an ac voltage across the EL panel 12 and thereby effecting excitation of the EL material and hence illumination of the EL panel 12.

Description

2340982 Vehicle Registration Plate The invention relates to a vehicle

registration plate, particularly but not exclusively for road vehicles.

It is a legal requirement in many countries that the rear registration plate on a road vehicle must be illuminated during the hours of darkness. Conventionally registration plates are illuminated by incandescent bulbs set at an acute angle to the surface of the plate. This generally results in a plate not being uniformly illuminated over the full area of the plate. As the reading distance increases it becomes progressively more difficult to read the numbers and/or letters, especially those located furthest from the light source. The legibility of plates is further reduced in wet, misty or foggy weather conditions and when dirt and debris become deposited on the bulb.

It is an object of the present invention to obviate or mitigate one or more of the disadvantages of the prior art.

The invention provides a vehicle registration plate comprising a panel member of electroluminescent material, a mask member masking the output of the panel member over a selected area or areas of the panel member to form at least one alphanumeric character, and an electrical power supply means electrically connected to the panel member and operable to cause the panel member to emit light.

The electroluminescent panel member desirably comprises two dielectric surfaces having a layer of electroluminescent material provided therebetween. The electroluminescent panel member preferably comprises plastics material sheeting between which there is a layer of electroluminescent material. The plastics material sheeting is desirably flexible. The electrolumines cent material is preferably a phosphor.

Attachment means are preferably provided for mounting the plate on a 2 vehicle. The attachment means may comprise a housing member. The housing member may comprise a reflective member provided between the panel member and the housing member for reflecting light from an external source and from the panel member. Desirably, the reflective member extends across substantially the full area of the panel member.

The mask member desirably comprises at least one mask element in the shape of an alphanumeric character, for forming a dark character against an illuminated background. The mask member may alternatively comprise a mask element having at least one aperture in the shape of an alphanumeric character, for forming an illuminated character against a dark background. The mask element preferably comprises a substantially optically nontransmitting material. A mask element is preferably provided on the external surface of the outwardly directed face of the panel member. A mask element may alternatively be provided within the panel member.

A laminate material may be applied to the outwardly directed face of the panel member, preferably over the mask element, to provide a protective coating on the surface of the panel member and on the mask element.

The electrical power supply means is preferably an alternating current electrical supply means. The ac electrical supply means preferably comprises an electrical inverter electrically connected to a direct current supply means. The dc supply means may be the electrical system of the vehicle, or may be a battery.

A specific embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic view from the front of a vehicle registration plate according to the present invention; Figure 2 is a diagrammatic view from one side of the vehicle registration 3 plate of figure 1; Figure 3 is a partial diagrammatic perspective view of one end of the vehicle registration plate on an enlarged scale; and Figure 4 is a schematic diagram of an electrical power supply for a vehicle registration plate according to the present invention.

Referring to the drawings there is provided a vehicle registration plate 10 comprising a panel member 12 of ele ctrolumine scent (EQ material. The EL panel 12 has mask members 14 provided on one face. These mask the output of the panel 12 over selected areas, to form a plurality of alphanumeric characters. An electrical power supply 16 is electrically connected to the EL panel 12, for applying an ac voltage across the EL panel 12 and thereby effecting excitation of the EL material and hence illumination of the EL panel 12.

The EL panel 12 comprises two pieces of flexible plastic sheeting, which form two dielectric surfaces, between which EL phosphor material is laminated. The EL panel is mounted in a housing 18, the housing 18 having attachment means (not shown) for mounting the registration plate 10 on a vehicle. The housing 18 may be made of metal or of a plastics material.

A mask 14 of letters and numerals is provided on the outwardly directed surface of the EL panel, the letters and numerals forming the registration number of the vehicle. A protective laminate 20 is provided on top of the mask 14 and the EL panel 12 to protect the mask 14 and the EL panel 12 surface from damage.

The ac electrical power supply 16 comprises a dc power supply source 22, which may be the vehicle electrical system, connected to an inverter 24, for converting the dc voltage supply into an ac voltage supply, of a required frequency. The output of the inverter 24 is connected to dielectric surfaces of the EL panel 12, to provide a voltage across the EL phosphor material in the EL panel 12. When the power supply 16 is on, voltage is applied across the EL phosphor material, which results in some of the electrons in the EL phosphor 4 material being excited. The excited electrons remain in the excited state for a certain length of time (the relaxation period) before relaxing to their unexcited state. The electron relaxation is accompanied by the release of one or more photons of light, which causes the EL panel 12 to become illuminated.

The frequency of the ac voltage is such that the ac period is at least equal to the relaxation period of the electrons, to ensure that once the electrons have been excited sufficient time is provided for the electrons to relax, and emit a photon, before the voltage is reapplied across the EL phosphor material. Each time an electron relaxes a photon is emitted, and the EL panel 12 is thereby illuminated by the phosphorescent light.

The mask 14 of letters and numerals comprises a material which is substantially optically nontransmitting, such as an opaque sheet material. This results in the illuminated registration plate 10 having an illuminated background (being the EL panel 12) with dark letters and numerals in the foreground, the result being that the registration number is presented in legible form.

In an alternative embodiment, the mask 14 is provided within the EL panel 12.

Various modifications may be made without departing from the scope of the invention. For example, the mask 14 may comprise a sheet of optically substantially nontransmitting material in which apertures having the shape of letters and/or numeral are provided. The illuminated registration plate 10 will therefore have the appearance of a dark background on which bright, illuminated letters are formed. Any material sufficient to provide adequate optical contrast could be used for the mask, but opaque or substantially opaque material is preferred. The mask 14 may also include a logo or device, such as the European Community symbol which is provided on vehicle registration plates in many countries, or other symbols identifying a country, region, state, town or city. The registration plate 10 may be of a different shape to that shown, as required by the relevant national laws.

It will be appreciated that the dc input 22 to the inverter 24 may be any dc power supply, such as a battery, and may be independent of the vehicle electrical system. Reflective material may be provided between the EL panel 12 and the housing 18, for reflecting light from the EL panel 12, to reflect any light emitted by the EL phosphor which is directed inwardly towards the housing. The reflective material may also reflect light from an external light source, to increase the visibility of the registration plate 10. It will further be appreciated that any suitable EL chemical compound may be used in place of the described EL phosphor.

There is thus provided a vehicle registration plate having improved readability under good and impaired atmospheric conditions even in the absence of secondary illumination from an external source. The present invention also provides a vehicle registration plate which is illuminated by an energy efficient light source. The energy supplied to the EL panel is only converted into light; no heat is generated, unlike conventional incandescent light sources. The illumination is provided evenly over the whole of the area of the panel (except where the panel is masked).

The registration plate is less vulnerable to deterioration in readability due to build up of dirt and debris on the light source, since the entire registration plate is back-illuminated by the EL panel. The use of back lighting also removes the presence of shadows on the registration plate, and increases the sharpness of the letters/numerals, which further increases the readability of the registration number. EL light sources have a very long life compared with standard incandescent bulbs and the deterioration of light properties and efficiency over time is insignificant compared to an incandescent light source. The vehicle registration plate of the present invention therefore offers increased lifetime and reliability as compared to conventional vehicle registration plates illuminated by incandescent light sources.

I I 6 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 emhasis has been placed thereon.

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Claims

1. A vehicle registration plate comprising a panel member of electrolumines cent material, a mask member masking the output of the panel member over a selected area or areas ot the panel member to form at least one alphanumeric character, and an electrical power supply means electrically connected to the panel member and operable to cause the panel member to emit light.

2. A vehicle registration plate according to claim 1, in which the electrolumine scent panel member comprises two dielectric surfaces having a layer of electroluminescent material provided therebetween.

3. A vehicle registration plate according to claim 2, in which the electroluminescent panel member comprises plastics material sheeting between which there is a layer of electroluminescent material.

4. A vehicle registration plate according to claim 3, in which the plastics material sheeting is flexible.

S. A vehicle registration plate according to any preceding claim, in which the electroluminescent material is a phosphor.

6. A vehicle registration plate according to any preceding claim, in which attachment means are provided for mounting the plate on a vehicle.

7. A vehicle registration plate according to claim 6, in which the attachment means comprises a housing member.

8. A vehicle registration plate according to claim 7, in which the housing member comprises a reflective member provided between the panel member and the housing member for reflecting light from an external source and from the panel member.

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9. A vehicle registration plate according to claim 8, in which the reflective member extends across substantially the full area of the panel member.

10. A vehicle registration plate according to any preceding claim, in which the mask member comprises at least one mask element in the shape of an alphanumeric character, for forming a dark character against an illuminated background.

11. A vehicle registration plate according to any preceding claim, in which the mask member comprises a mask element having at least one aperture in the shape of an alphanumeric character, for forming an illuminated character against a dark background.

12. A vehicle registration plate according to claim 10 or 11, in which the mask element comprises a substantially optically nontransmitting material.

13. A vehicle registration plate according to any preceding claim, in which a mask element is provided on the external surface of the outwardly directed face of the panel member.

14. A vehicle registration plate according to any preceding claim, in which a mask element is provided within the panel member.

15. A vehicle registration plate according to any preceding claim, in which a laminate material is applied to the outwardly directed face of the panel member.

16. A vehicle registration plate according to claim 15 when dependent on claim 13, in which the laminate material is applied over the mask element, to provide a protective coating on the surface of the panel member and on the mask element.

17. A vehicle registration plate according to any preceding claim, in which 9 the electrical power supply means is an alternating current electrical supply means.

18. A vehicle registration plate according to claim 17, in which the ac electrical supply means comprises an electrical inverter electrically connected to a direct current supply means.

19. A vehicle registration plate according to claim 18, in which the dc supply means is the electrical system of the vehicle.

20. A vehicle registration plate according to claim 18, in which the dc supply means is a battery.

21. A vehicle registration plate substantially as described above with reference to the accompanying drawings.

22. 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.