Licence plates on motor vehicles are an important tool for identification of vehicles. Most jurisdictions require that a licence plate appear at least on the rear of the vehicle. In this way, vehicles approaching from behind can quickly identify the vehicle in front. This is most important for police activities which, with modern techniques, allow a determination as to whether the vehicle is stolen or subject to unpaid traffic violations without the need for a police officer to confront the driver.
Typically, licence plates are stamped from a single piece of sheet metal. Embossed letters or numbers form a unique identifying code and are typically painted a different colour from the background of the licence plate. In addition, other indicia such as the logo or motto of a particular jurisdiction may be embossed and painted in order to individualize licence plates for each jurisdiction.
Modern licence plates are made visible at night in two ways. First, the embossed letters, numbers and symbols may be coated with a reflective paint so that when the headlights of a vehicle approaching from the rear illuminate the licence plate, a significant amount of light is reflected from those specially painted areas. Indeed, both the background and the embossed letters, numbers and symbols may be painted with reflective paints of different colours so that each stands out. In addition, or in the alternative, external lighting in the well in which the licence plate sits may be directed onto the licence plate in order to ensure adequate illumination and visibility from a distance.
Nonetheless, dust, oil, and other grime can collect on the surface of a licence plate thus severely decreasing its reflectiveness. Accordingly, whether illuminated from lighting in the licence plate well, or by approaching headlights, the licence plate may not be as visible as desired. Also, external lighting in the licence plate well of a vehicle may be exposed to damage by collision, random debris or vandalism. When external lighting ceases to function, visibility decreases.
Also, in some situations, it is advantageous to identify a vehicle without shining headlights from another vehicle onto its licence plate. Illumination provided by light reflected from the external lighting in the licence plate well may be insufficient to permit such identification. If the licence plate well lighting is not functioning, no licence plate illumination will occur in these circumstances.
One solution to these problems is to illuminate a licence plate from the inside rather than from the outside as described above. Thus, holes are punched into the sheet metal which forms the licence plate, and glass numbers, letters or symbols corresponding to the punched out portions of the sheet metal are inserted therein. When illuminated from behind, the letters, numerals or symbols will be highly visible to a person viewing the vehicle despite a certain amount of dust or grime on the external surface thereof since illumination does not depend upon reflectivity from the external surface. An internally illuminated licence plate will be visible despite ambient light conditions whether mounted on the front or the rear of a vehicle. Such a licence plate also provides a safety advantage since a car with a missing headlight or taillight can never be mistaken for a motorcycle given the unmistakable positioning of an illuminated licence plate on the front or rear of the vehicle respectively. Although such licence plates have been proposed in the past, to date, none of them has been commercially successful since they are not of a sturdy enough construction to withstand the rigors of motoring, or are too costly to produce.
Accordingly, it would be an advantage to provide a licence plate of sturdy construction wherein the letters, numerals and symbols to be illuminated would be firmly connected to an opaque face plate. It would be a further advantage to provide a licence plate adapted to be illuminated from the vehicle side of the plate rather than by sources outside the vehicle. A licence plate which is equally visible under all light conditions whether mounted on the front or rear of the vehicle, or on both the front and rear, would provide additional advantages.
In accordance with a principal aspect of the invention, a licence plate adapted for illumination comprises an opaque face plate having outward-facing and inward-facing faces, and comprises cut-out areas corresponding to numerals, letters, symbols or designs; and a translucent, heat-deformable backing plate heat-pressed against the inward-facing face of said face plate to force portions of the backing plate into the cut-out areas; such that when the licence plate is illuminated from a point inward of the backing plate, the portions of the backing plate within the cut-out areas are illuminated for viewing from a point outward of the face plate.
In further aspects of the invention:
(a) the translucent backing plate comprises a heat-deformable thermoplastic material which is rigid at normal ambient air temperatures;
(b) the heat-deformable thermoplastic material remains rigid at temperatures below about 150xc2x0 Fahrenheit;
(c) the opaque face plate comprises a metal resistant to weathering;
(d) the metal comprises stainless steel.
In a further aspect of the invention, a licence plate assembly comprises: a housing comprising a source of light; an opaque face plate having outward-facing and inward-facing faces, and comprising cut-out areas corresponding to numerals, letters, symbols or designs, the face plate adapted to be mounted to the housing; a translucent, heat-deformable backing plate heat-pressed against the inward-facing face of the face plate to force portions of the backing plate into the cut-out areas; such that when the face plate with the backing plate is mounted to the housing, an enclosure is formed and the source of light may illuminate the portions of the backing plate in the cut-out areas for viewing from a point outward of the face plate.
In further aspects of the invention, the licence plate assembly:
(a) further comprises a gasket between the face plate and the housing to seal the enclosed housing of the licence plate assembly from contamination;
(b) the gasket comprises a flexible synthetic rubber or thermoplastic material;
(c) further comprises a hinge connection between the face plate and the housing, to permit the face plate to be hingedly opened to facilitate maintenance and replacement of the light source;
(d) the source of light comprises an incandescent electrical light bulb;
(e) the light bulb is adapted to generate heat during operation sufficient to melt ice and snow accumulated on the face plate;
(f) the face plate is mounted to the housing by means of a fastener;
(g) the fastener comprises a screw;
(h) the fastener comprises a latch.
In a further aspect of the invention, a method of manufacturing a licence plate adapted for illumination comprises: cutting openings in a metal face plate using a laser to create neat cut-out areas corresponding to numerals, letters, symbols or designs; pressing a substantially rigid, translucent, heat-deformable thermoplastic backing plate against the face plate with sufficient force and at a sufficient temperature to deform the backing plate and to force portions of the backing plate through the cut-out areas without disrupting the unity of the backing plate, and to fix the backing plate to the face plate; cooling the combined face plate and backing plate to permit the backing plate to return to a substantially rigid state.
Further aspects of the invention will become apparent from the following detailed description of the invention.