GB2038527A - Display devices - Google Patents

Abstract

A display device, in particular a motor vehicle number plate, comprises a character support sheet (1) of transparent or translucent material, preferably a plastics material, a backing sheet (2) spaced from the support sheet (1) and having a highly reflective surface (4) facing the support sheet (1), and a light source (3), preferably a cold cathode fluorescent tube, directing light, either directly or indirectly via light transmitting means, into an edge (5) of the support sheet (1) and into the space (6) between the support sheet (1) and the backing sheet (2). The characters (7) are engraved on the support sheet (1) and then may be painted. The lamp (3) is shielded against emergence of extraneous light and is supplied from the vehicle battery via an inverter. <IMAGE>

Description

SPECIFICATION Display devices This invention relates to a display device, and is particularly although not exclusively concerned with a device for displaying on a vehicle the combination of letters and numbers which constitute a registration identification (or 'number') of the vehicle.

It is known to display a vehicle registration number on a translucent plate which is illuminated from behind with an electric light. With this arrangement at night time the number can be displayed in a clearly visible and distinctive manner. However, the positioning of the electric light behind the number plate gives rise to a construction which may be too large, in terms of the front-to-back dimension thereof, for convenient application to a small motor vehicle such as a domestic motor car.

Also, the present requirement is that the number should be displayed on a highly reflective background whereby it is now usual to provide a number plate which is formed from a highly reflective material which is opaque and which therefore cannot be illuminated from behind. It is indeed known to provide local illumination for an opaque number plate but this is usually effected with an electric light in front of the plate and this arrangement may not be capable of producing a night-time display of the number which is as prominent and distinctive as the display which can be achieved with the abovementioned rear-lit arrangement.

An object of the present invention is to provide a display device with which markings on a support sheet, such as a number on a vehicle number plate, can be illuminated in a manner suited to the production of a prominent and distinctive night-time display thereof, whilst presenting the markings against a highly reflective background and without requiring a large construction in terms of the front-to-back dimension thereof.

According to the invention therefore there is provided a display device comprising a transparent or translucent support sheet, markings applied to a surface of said support sheet, a backing sheet spaced from said support sheet and having a highly reflective surface facing said support sheet and a light source arranged to direct light into said support sheet from an edge region thereof and into the space between said support sheet and said backing sheet.

With this arrangement, due to the use of light transmitted through the sheet to illuminate the markings, a prominent and distinctive night-time display can be achieved; whilst at the same time, in so far as the light source is required to provide light at an edge region of the sheet, no problems need arise with regard to the simultaneous provision of an adequately reflective background and satisfactory transmitted illumination and also there is no need for the front-to-back dimension of the device to be unduly large.

It is visualised that the invention will find particular application in the context of a motor vehicle (particularly a motor car) number plate, and in this respect it will be appreciated that the device can conveniently be used at the front of the vehicle and/or at the rear thereof. However, it is to be understood that the invention is not intended to be restricted to this field of use and the display device may be used to display any suitable marking for any suitable purpose.

With regard to the support sheet, this may be formed from any suitable material including glass and plastics material. Also the markings may be applied to the sheet in any suitable manner. In a particularly preferred embodiment, however, the sheet is injection moulded from a rigid or semi-rigid transparent plasstics material, such as diakon, and the markings are applied thereto by an engraving technique. Such engraved markings may also be painted and suitably a dark paint may be used for the body of the markings and a light paint may be used for an outline around the markings.

The backing sheet, having a highly reflective surface, constitutes a sheet disposed behind and in spaced relationship to the support sheet. With this arrangement a particularly distinctive three-dimensional effect can be produced.

The light source may be situated in the region of an edge of support sheet and the space between the support sheet and backing sheet, or alternatively may be disposed elsewhere with an appropriate light transmitting or reflecting system interposed between the source and the aforesaid region. The light source may take any suitable form but preferably is a fluorescent lamp of elongate tubular form, having a cold cathode to reduce the risk of fire, heat distortion and breakage if the display device is immersed in or showered with cold water.

The invention will now be described further by way of example only and with reference to the accompanying drawing which is an elevation and sectional end view of one form of a display device according to the invention.

The display device is for mounting at the front or back of a motor car for displaying the registration number of the car, and comprises two rectanguler plates 1, 2 mounted (by means not shown) at an appropriate position on the vehicle with the plate 1 parallel to and spaced a short distance in front of the plate 2.

The plate 1 is the support sheet and is a transparent rigid or semi-rigid sheet of diakon.

The plate 2 is the backing sheet and a rigid or semi-rigid sheet of a suitable material having intrinsic high light reflecting properties or coated with a high reflective substance on the surface 4 facing the support plate 1. The highly reflective material or coating may be of a conventional form involving a three-dimensional structure or paint or layer of reflective beads or particles which acts to reflect light perpendicularly away from the surface of the plate even when illuminated with light which is not wholly perpendicular thereto.

Above the plates there is mounted an elon gate tubular fluorescent lamp 3 and this is appropriately housed so as to be shielded from the front, back, top and ends thereof (by known means not shown for clarity). The lamp 3 is connected to an appropriate operating circuit (not shown) powered from the motor car- battery, such circuit including an inverter to produce the requisite high voltage. The lamp 3 is preferably of the cold cathode type in order to reduce the risk of fire, heat distortion or breakage if the number plate is contacted by cold water.

The support sheet 1 has a combination of letters and numbers 7 engraved thereon from tne rear and each letter/number is painted black with a white outline.

The letters/numbers 7 are clearly visible in natural daylight. At night-time the letters/numbers 7 can also be clearly seen in artificial light due to reflection of incident such light by the reflective plate 2. Also at nighttime the fluorescent lamp 3 can be illuminated so as to direct light on to the letters/numbers 7 by transmission from the lamp 3 through the plate 1 from the top edge 5 thereof, and also by virtue of light from the lamp 3 directed downwardly into the space 6 between the plates 1, 2. The letters/numbers 7 intercept such light transmitted through the plate 1 and are illuminated thereby particularly in the vicinity of the white painted outlines thereof. In this way the letters/numbers 7 are displayed in a particularly prominent and distinctive manner and appear as brightly illuminated characters suspended in front of the reflective backing sheet 2.

It will be appreciated that this advantageous effect is achieved in a simple and convenient manner and without requiring an unduly large- front-to-back dimension for the display device.

The support sheet 1 is preferably injectionmoulded of diakon, in which case the number plate will be very hard to resist scratching and breakage if hit by a stone thrown up from the road by another vehicle.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only. For example in the embodiment shown the reflective surface 4 of the backing sheet 2 is that surface remote from the support sheet 1 and in this case the light source 3 is. positioned so as to direct light into the backing sheet 2 from the top as well as into the support sheet 1 and the space 6 between the sheets 1, 2.

However, the reflective surface of the backing sheet 2 may be that surface nearest the support sheet 1 and the light from the lamp 3 be directed into the support sheet 1 and the space 6 only.

As a further or alternative feature the support 1 and/or the backing sheet 2 may be tapered in thickness from relatively wide adjacent the light source 3 to relatively narrow at the edge remote therefrom. In either of such cases preferably the mutually remote surfaces of the support and backing sheets 1, 2 are substantially parallel with each other and the taper is provided by the non-parallel mutually facing surfaces of the support and backing sheets 1, 2.

The fluorescent tube 3, which as stated previously is preferably of the cold cathode type, may comprise a straight tube having pin type electrodes 8, at the ends thereof. By use of such a tube light is emitted from substantially the whole length of the tube, whereas with conventional tubes there is a region of approximately 4 cms at each end in the region of the cathode, from which light is not emitted and in which a considerable voltage drop is experienced. With a tube of the present type the aforementioned voltage drop is considerably reduced and a greater and more even light output is achieved for the same power input than is achieved with conventional tubes. A tube of the present type is more fully described in and is the subject of our co-pending Patent Application No.

7941017 (M'Caw file reference 12175 A).

Claims (11)

1. A display device comprising a transparent or translucent support sheet, markings applied to a surface of said support sheet, a backing sheet spaced from said support sheet and having a highly reflective surface facing said support sheet and a light source arranged to direct light into said support sheet from an edge region thereof and into the space between said support sheet and said backing sheet.

2. A display device according to claim 1, wherein the support sheet is of a plastics material.

3. A display device according to claim 1 or claim 2, wherein the backing sheet is of a plastics material.

4. A display device-according to claim 2 or claim 3,-wherein the sheet or sheets is or are of diakon.

5. A display device according to any one of claims 2 to 4, wherein the markings are engraved upon the support sheet.

6. A display device according to claim 5, wherein the engraved markings are painted.

7. A display device according to any preceding claim, wherein said light source is situated in the region of an edge of the support sheet and the space between the support sheet and backing sheet.

8. A display device according to any one of claims 1 to 6, wherein said light source is situated away from said device and a light transmitting means is disposed between said light source and the region of an edge of the support sheet and the space between the support sheet and backing sheet.

9. A display device according to any preceding claim further comprising shield means adapted to prevent light from said light source passing directly away from said light source in a direction other than into said support sheet and said space.

10. A display device according to claim 3 wherein the highly reflective surface of the backing sheet is that surface remote from the support sheet.

11. A display device according to claim 10 wherein the light source is situated in the region of and is arranged to direct light into an edge of the backing sheet, an edge of the support sheet and the space between said backing and support sheets.

1 2. A display device according to any preceding claim wherein said support sheet has a thickness which tapers away from the edge into which light is directed.

1 3. A display device according to claim 1 2 when dependent upon claim 11 wherein said backing sheet has a thickness which tapers away from the edge into which light is directed.

1 4. A display device according to claim 1 3 wherein the mutually remote surfaces of said support and backing sheets are substantially parallel and the mutually facing surfaces thereof are non-parallel.

1 5. A display device according to any preceding claim wherein said light source comprises a fluorescent tube lamp.

1 6. A display device according to claim 15, wherein said light source comprises a fluorescent tube lamp having a cold cathode.

1 7. A display device according to claim 1 6 wherein said fluorescent tube comprises a straight tube having a pin-type electrode at each end thereof.

1 8. A display device according to any one of claims 1 5 to 1 7 further comprising an inverter adapted to be supplied with electrical energy by a battery and to supply electrical energy to said fluorescent tube.

1 9. A display device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.