Flexible lighting strip - Patent Review 4107767

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This invention relates to a flexible electric lighting strip.

It is an object of the present invention to provide a flexible lighting strip which can be made in any length. It can, if necessary, be as long as 10 metres, or even longer, so that complete illumination of an area, for example a recess or a showcase in a dwelling or a shop, can be effected.

The strip in accordance with the invention comprises an elongate section of plastics material including a cylindrical cavity containing a chain of electric lamps; a rear portion containing longitudinal supply conductors for feeding the lamps from an electricity supply, the rear portion being filled with a translucent compound which adheres to the plastics material of the section; and a middle portion between the cavity and the rear portion and having a longitudinal triangular slit with its apex in communication with the cylindrical cavity; the strip further including a plurality of conductors interconnecting the supply conductors and the lamps and extending through and gripped at said apex; and a metallic sheet at the rear of the translucent compound and adhered to the compound.

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

FIG. 1 is a transverse section through a flexible lighting strip in accordance with the invention, and

FIG. 2 is a diagrammatic representation of the wiring of a chain of lamps in series-parallel.

Referring to FIG. 1, a section 1 of a plastics material capable of withstanding the heat produced by the lamps when operating comprises a portion having a longitudinal cylindrical cavity 1c and a portion extending therefrom which has a central slit 1a of triangular cross-section opening at its apex into the cylindrical cavity 1c. This portion also has longitudinal grooves carrying uninsulated conductors 3 and 4. The material is preferably a silicone rubber, such as that sold by the Rhone-Poulenc Company in Paris under the trade name "RHODORSIL RP 60". The portion containing the conductors 3 and 4 is filled with a translucent polymerisable compound 5, which insulates the conductors 3 and 4 and holds them in place. The translucent compound may be that sold by Barthelemy factory at Bobigny under the trade name "GEBSICONE".

A thin sheet 6 of polished aluminium or light alloy or other metal is adhered to the compound 5 by polymerisation of the compound, and acts as a reflector of the light emitted by the lamps 9 which are housed in the cavity 1c. The metallic sheet may be, for example, 10/100 m.m. thick.

A tape 7 of high-density polyurethane foam is provided with adhesive layers 7a and 7b on its opposite surfaces. The layer 7b adheres the tape to the sheet 6, so that the sheet 6 not only provides a reflecting surface but also provides a surface for adhesion of the tape 7, which would not adhere directly to the translucent compound. The layer 7a is covered with a paper backing layer 8 which can be pulled off so that the layer 7a can be used to fix the lighting strip in place in the area to be lit, such as on a piece of furniture, or round the periphery of a recess or a showcase.

FIG. 2 shows a suitable arrangement of the lamps 9 wherein they are connected in chains of nine lamps each between the supply conductors 3 and 4, so that a voltage of about 12 volts appears across each lamp when the conductors 3 and 4 are connected to a supply main having a voltage of 110/125 volts, or a voltage of about 24 volts appears across each lamp if the supply main voltage is about 220 volts. The points of connection between the chains of nine lamps are connected alternately to the conductor 3 and the conductor 4 by conductors 2a - 2c in such a way that the chains are supplied at the same voltage.

The conductors 2a - 2c etc. (exemplified by the conductor 2 in FIG. 1) pass through the slip 1a into the cavity 1c where they are connected to the lamp chains. The conductors are gripped at the edge 1b of the slit and are thereby held in place.

At the free end of the strip, the spacing of the lamps 9 in the last chain may be adjusted so that the strip can be cut to length in the immediate vicinity of one of the tapping conductors 2a, 2b, 2c etc, so that the strip is luminous over its whole length.

It is advantageous, in order to avoid abnormally high temperatures over certain sections of the strip when placed vertically, to provide, at least at the ends of the strip, plugs of the same polymerisable translucent compound, one of the plugs also acting to integrate the insulating sheaths of the supply cable, which sheaths are of the same plastics material as the strip, with the filling of compound and the plastics section. In certain cases it is also advisable, for the same reason, to provide, in particular in very long lighting strips, intermediate plugs of the same compound in positions such as between the individual chains of lamps.

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