EP0756132A1

EP0756132A1 - Reduced-thickness motor vehicle lamp

Info

Publication number: EP0756132A1
Application number: EP96112127A
Authority: EP
Inventors: John Monk
Original assignee: Magneti Marelli SpA
Current assignee: Marelli Automotive Lighting Italy SpA
Priority date: 1995-07-28
Filing date: 1996-07-26
Publication date: 1997-01-29
Also published as: ITTO950639A0; ITTO950639A1; IT1280453B1

Abstract

The motor vehicle lamp (1) comprises a laminated polymeric light-emitting diode (2), a coloured film (3) to filter the rays emitted by the light-emitting diode (2) and a transparent lens (4). The light-emitting diode (2) comprises two electrodes (5, 6) between which two polymeric layers (7, 8) are arranged in contact. The light-emitting diode (2), the coloured film (3) and the lens (4) are separated from each other by gaps.

Description

The present invention relates to a reduced-thickness motor vehicle lamp.
As is well known, present-day lighting units for motor vehicles comprise a light source (bulb) that generates a light beam, a reflector with a reflective surface that receives the light beam generated by the source and distributes it within a limited solid angle, and a transparent prismatic cover made up of a plurality of prismatic diffusing lenses that spread the light beam out into a larger solid angle in accordance with the vehicle light regulations in force.
However, the thickness of lamps of this sort is quite considerable and such as to require, for mounting purposes, large intrusions into the bodywork of the motor vehicle. In fact these intrusions often require that the bodywork of the vehicle be cut through and this raises the cost of fitting the lamp. Many solutions to this problem have already been proposed, all with the purpose of reducing the thickness of the lamp and so limiting the intrusion of the lamp into the bodywork of the vehicle. Some of these proposals are based on the use of light-emitting diodes (LEDs) for the light source; others, on the use of lamps with Fresnel lenses in order to eliminate the reflectors, and still others on the use of lamps with lightguides and optical guides of diffractive type.
There are however certain disadvantages to the proposed solutions. The use of LEDs as light sources, for example, requires the use of many LEDs for each function of the lamp or else limits the size of the lamp allocated to each function. On the other hand, the use of the other solutions conflicts with the need for a flexible light source adaptable to the great variety of shapes of motor vehicle bodywork and does not simplify the operations of fitting the lamp.
The object of the present invention is therefore to provide a motor vehicle lamp that does not have the drawbacks described above.
The present invention provides a motor vehicle lamp comprising a light source capable of generating a light beam, which lamp is characterized in that said light source comprises a laminated polymeric light-emitting diode (LED).
In order that the present invention may be understood more clearly, a preferred embodiment will now be described, purely by way of a non-restrictive example, with reference to the accompanying drawings in which:

Figure 1 shows one embodiment of the lamp according to the invention, in a perspective view; and
Figure 2 shows a horizontal section through the lamp shown in Fig. 1.

In the figures the lamp according to the invention is marked 1. The lamp 1 is intended to be mounted on the bodywork 10 of a motor vehicle and comprises a polymeric LED 2 acting as the light source, a thin coloured film 3 acting as an intermediate filter and an external lens 4 of transparent plastic. The polymeric LED 2 is made of organic semiconductors in a flat laminated structure and its emitting area is equal in dimensions to the area needed for the particular function.
In particular the polymeric LED 2 comprises a first and a second electrode 5, 6 between which two polymeric layers 7, 8 are positioned in contact with each other. A direct-current generator 9 is connected up between the first electrode 5 and the second electrode 6 in order to polarize the polymeric LED 2.
The physical principles that govern the emission of light by a polymeric LED are explained in greater detail in an article published in the November 1992 issue of Physics World under the title "Polymer LEDs", by Richard Friend, Donald Bradley and Andrew Holmes, in which the structure and operation of a polymeric LED having a single polymeric layer are described.
Lastly, the external lens 4 has a first face 4a turned towards the bodywork 10 of the motor vehicle and a second face 4b on the other side. The film 3 is arranged between the second electrode 6 of the polymeric LED 2 and the face 4a of the transparent lens 4 and is separated from each of these by a small spacer gap 11, 12, respectively.
The lamp 1 according to the present invention operates in the following manner: the polymeric laminated LED 2 emits light which is filtered by the coloured film 3 in order to ensure that the colour of the light as it leaves the lamp 1 complies with the regulations in force. The gaps 11, 12 between the polymeric LED 2 and the film 3, and between the film 3 and the external lens 4 make it possible to achieve greater uniformity of the light leaving the lamp 1, while the lens 4 makes it possible spatially to distribute and control the light beam emitted by the polymeric LED 2 in accordance with the requirements of the various functions of the lamp 1.
The advantages of the present lamp are as follows: the use of a polymeric laminated LED provides a light source that has no dimensional limitations and is flexible and adaptable to the wide variety of curves of motor vehicle bodywork. The total thickness of the lamp is also small enough to enable it to be attached to the bodywork of the motor vehicle with the least possible intrusion into the bodywork and without the need for cutting for the surface mounting of the functions. It is therefore possible greatly to simplify the operations of mounting the lamp and sharply to reduce the costs of assembly.
Finally, it will be clear that the device described and illustrated here can be modified and altered without thereby departing from the scope of the present invention. It is possible, for example, to arrange the coloured film 3 acting as the intermediate filter in direct contact with the polymeric LED 2 and with the external lens 4 when the parameters of uniformity of the light emitted by the polymeric LED are already respected. Alternatively it is possible to dispense completely with the coloured film in those cases in which the light emitted by the polymeric LED already conforms with the relevant regulations on the colour of the light emitted by the lamp.

Claims

Motor vehicle lamp (1) comprising a light source (2) capable of generating a light beam, which lamp is characterized in that said light source comprises a laminated polymeric light-emitting diode (LED) (2).
Motor vehicle lamp according to Claim 1, characterized in that said polymeric LED (2) comprises a first electrode (5) and a second electrode (6), and a first polymeric layer (7) and a second polymeric layer (8), said first (7) and second (8) polymeric layers being positioned in contact with each other between said first (5) and second (6) electrodes.
Motor vehicle lamp according to Claim 1 or 2, characterized in that it comprises a transparent external lens (4) for distributing and controlling the said light beam.
Motor vehicle lamp according to Claim 3, characterized in that said lamp (1) is intended to be mounted on the bodywork (10) of a motor vehicle, in that said transparent lens (4) has a first face (4a) and a second face (4b), said first face (4a) being turned towards said bodywork (10), and in that said polymeric LED (2) is positioned in contact with said first face (4a) of said transparent lens (4).
Motor vehicle lamp according to Claim 3, characterized in that said lamp (1) is intended to be mounted on the bodywork (10) of a motor vehicle and in that said transparent lens (4) has a first face (4a) and a second face (4b), said first face (4a) being turned towards said bodywork (10), and in that said polymeric LED (2) is separated by a gap from said first face (4a) of said transparent lens (4).
Motor vehicle lamp according to any one of Claims 3 to 5, characterized in that a coloured film (3) is arranged between said polymeric LED (2) and said first face (4a) of said transparent lens (4) to filter the light emitted by said polymeric LED (2).
Motor vehicle lamp according to Claim 6, characterized in that said film (3) is positioned in contact with said polymeric LED (2) and said first face (4a) of said transparent lens (4).
Motor vehicle lamp according to Claim 6, characterized in that said coloured film (3) is separated by a gap from said polymeric LED (2) and from said first face (4a) of said transparent lens (4).