EP4174363A1

EP4174363A1 - Light strip and corresponding manufacturing method

Info

Publication number: EP4174363A1
Application number: EP22204163.4A
Authority: EP
Inventors: Edin DEDOVIC
Original assignee: Linea Light SRL
Current assignee: Linea Light SRL
Priority date: 2021-10-28
Filing date: 2022-10-27
Publication date: 2023-05-03
Also published as: IT202100027629A1

Abstract

Light strip (10) comprising: a flexible printed circuit (11) provided with a series of supports (12) located in sequence in a longitudinal direction (Y); one or more light sources (13) positioned on said supports (12); a profile (14) for containing said flexible printed circuit (11); and a cover (15).

Description

FIELD OF THE INVENTION

The present invention concerns a light strip and the corresponding manufacturing method, in particular in the field of lighting technology to make light strips which support light sources along their length, for example but not exclusively LEDs (Light Emitting Diodes).
The strips can be applied on profiles, tables, door and window frames, furnishing components in general, portions of walls, floors, ceilings and false ceilings, and in other various applications, internal or external, in which particular aesthetic and/or focused and/or distributed lighting effects are to be achieved.

BACKGROUND OF THE INVENTION

Light strips are known which can be used in the field of lighting engineering and furnishing to create light points/zones distributed in specific portions of wall elements or furnishing components.
The development of LED and Oled (Organic LED) technology, together with increasingly advanced architectural requirements and proposals, has made it possible to develop technologically advanced solutions, enabling the creation of extremely sophisticated lighting effects, particularly in combination with profiles and edges of furnishing components, as well as doors and windows, partition walls, external walls and more.
A light strip of this type normally consists of a longitudinal support, with length prevailing over width, made of normally flexible material on which a thin single or double-layer copper coating is applied, which creates the conductive track or tracks for the electric power supply of the light sources.
This combination of flexible support and conductive coating forms a so-called PCB (Printed Circuit Board) on which the light sources are applied, as well as the corresponding electric/electronic power supply and management components, and from which the light sources derive their electric power.
In correspondence with the positioning of the light sources, a base made of rigid material is normally provided, which forms a stable support to correctly position and maintain in position the light sources, and ensures the necessary mechanical stability of the strip, as well as of the welds and electrical connections. Once the desired arrangement of the light sources has been obtained, the strip is coupled with a profile made of plastic material or silicone, and the whole thing is then embedded in a resin, or similar material, which seals and defines the final shape of the strip.
The resin, usually of silicone material, ensures a high electrical insulation, making the strip applicable also outside.
One problem found in known solutions is that the strip, once completed, has little capacity to flex and bend with respect to at least two planes in space, for example in order to form a three-dimensional light element, since the internal rigidity of the connections can cause the breakage and/or interruption of the electrical connections.
This constitutes a limit for the possible applications and installations of said strips since they are unable to satisfy the increasingly advanced requirements and needs of architects and interior designers.
Document US 2019/230782 A1 describes a light strip comprising a flexible printed circuit contained by a profile provided with a series of supports located in sequence with each other which accommodate one or more light sources. The supports are reciprocally distanced by interruptions and electrically connected by means of a plurality of fins positioned on only one side of the circuit.
The fins, since they are located only on one side of the circuit, allow a limited supply of electric current to the light sources and furthermore the light strip obtained is asymmetrical with respect to a longitudinal axis, hence its structural resistance and the possibility of it being curved in space are limited.
Document US 2003/071581 A1 describes a light strip provided with fins on both sides of the printed circuit.
However, in order to connect the fins to the printed circuit, welds and connections are necessary, which lead to complications in manufacturing the circuit. Furthermore, the structural strength of the light strip is limited, and the welds and connections can deteriorate over time, with the risk that the electrical connection may be interrupted. Moreover, this light strip is intended for a flat application, and is therefore not suitable for three-dimensional curvatures.
Document WO 2019/175914 A1 describes another light strip in which the connection between the various supports or bases occurs at the center and not on both sides of the printed circuit. To ensure a certain flexibility of the light strip, the printed circuit is mechanically bent in the vicinity of the central connections.
This light strip, due to the single central connection, can be improved from a structural point of view, in terms of resistance to wear and the supply of current to the light sources. Furthermore, due to the bends, it is difficult to guarantee a constant distance between the bases.
Document WO 2014/114415 A1 describes another light strip, asymmetrical with respect to a longitudinal axis, which therefore substantially has the same problems as highlighted for US 2019/230782 A1 .
One purpose of the present invention is therefore to provide a light strip which increases the degree of flexibility and torsion compared with known solutions, allowing it to be bent on several planes with respect to space, with large degrees of freedom and without the risk of breakage, with solid welds, without the formation of cracks and interruptions, even only partial, in the electrical connections.
Another purpose of the present invention is to obtain a light strip which can be bent on at least two planes in which neither the correct optical emission of the light sources nor the continuity of the light and/or the correct maintenance of a regular and constant pitch between the light sources are compromised.
Another purpose of the present invention is to obtain a light strip which can be curved/bent both on a plane transverse to a base surface of the strip, and also on the containing plane of the base surface itself, allowing to obtain a plurality of three-dimensional shapes.
Another purpose of the present invention is to perfect a method for manufacturing said strips which is in any case fast and economical, at the same time guaranteeing that the advantages indicated above are achieved.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.
In accordance with the above purposes, a light strip according to the present invention comprises: a flexible printed circuit provided with a series of supports located in sequence in a longitudinal direction; one or more light sources positioned on such supports; a profile for containing the flexible printed circuit; and a cover.
The supports are reciprocally distanced by interruptions and electrically connected by means of a plurality of fins which are positioned at the side of the supports and of the interruptions.
According to one aspect of the invention, the flexible printed circuit develops along a longitudinal axis of symmetry; furthermore, the fins extend on both sides of the circuit and are made in one piece with the supports.
In this way, a light strip is obtained that is symmetrical with respect to the longitudinal axis of symmetry, and which therefore has high structural strength and bends homogeneously in any direction whatsoever. In this light strip, an electrical connection on both sides of the circuit is substantially created, thus allowing to use a double track for the electrical connection of the bases, with a consequent greater input of current, keeping the thickness of the printed circuit unchanged. This allows to manufacture light strips that are longer in length and also more wear resistant than light strips known in the field.
The flexible printed circuit provides fins and supports made in one piece. Therefore, no soldering or connections between these components are required. The fins are also able to bear the supports on both sides, creating a light strip that is extremely resistant.
The fins connect the supports electrically and physically and allow, even in steps that follow the coupling with the containing profile and with the cover, to flex and bend the light strip on two or more planes in space, according to the specific shape to be taken for the specific application.
In this way, the light strip is perfectly adaptable and malleable in order to follow even the most particular and complex shapes and profiles, for example the edge of a curvilinear furnishing component, even if it is not regular, a profile of an internal or external wall, or whatever else is required by the specific application.
With these fins and supports separated by interruptions, the present light strip can be bent more than a traditional light strip, therefore with lower radii of curvature than the radii of curvature normally achievable with a traditional light strip, without the risk of compromising its integrity and correct operation.
According to another aspect of the invention, the fins are positioned on a plane which is substantially orthogonal or slightly inclined with respect to a plane on which the flexible printed circuit lies.
According to another aspect of the invention, the fins have the shape of an arc or suchlike.
According to another aspect of the invention, the interruptions are positioned at a constant pitch along the longitudinal extension of the flexible printed circuit.
According to another aspect of the invention, the fins are positioned at a constant pitch along the longitudinal extension of the flexible printed circuit.
According to another aspect of the invention, the fins located on one side of the flexible printed circuit mirror the fins located on the opposite side.
According to another aspect of the invention, the profile comprises opposite lateral walls provided with a tooth which is configured to allow a mechanical coupling of the fins with the profile.
According to another aspect of the invention, the tooth comprises, at the upper part, an inclined plane which facilitates the insertion of the circuit in the support and, at the lower part, an abutment surface for the fins. The circuit can therefore be inserted in the profile substantially in a snap-in manner.
According to another aspect of the invention, the tooth extends on each of the lateral walls for the whole extension of the profile.
The invention also concerns a method for manufacturing a light strip, comprising the following steps:

preparing a flexible printed circuit which develops along a longitudinal axis of symmetry and is provided with a series of supports located in sequence and reciprocally distanced by means of interruptions in a longitudinal direction and on which there are positioned one or more light sources, which are electrically connected by means of a plurality of fins which are positioned on both sides of the circuit and are made in one piece with the supports;
inserting the flexible printed circuit equipped with the supports and the fins in an open containing profile;
inserting a resin in the profile, thus obtaining a protective cover of the light strip.

According to another aspect of the invention, the fins are bent toward the inside of the light strip, that is, toward the flexible printed circuit, in such a way that they are disposed on a plane substantially orthogonal or slightly inclined with respect to a plane on which the flexible printed circuit lies.

DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

fig. 1 is a plan view of a part of a light strip according to the present invention provided with a flexible printed circuit;
fig. 2 is a longitudinal section view along the line II-II of fig. 1;
fig. 3 is a cross-section view of the light strip of fig. 1;
fig. 4 is a plan view of a part of a light strip according to a variant of the present invention;
fig. 5 is a longitudinal section view along the line V-V of fig. 4;
fig. 6 is a cross-section view of the light strip of fig. 4;
fig. 7 is a plan view of the flexible printed circuit;
fig. 8 is a lateral view of the printed circuit of fig. 7;
fig. 9 is an enlarged lateral view of a part of fig. 7;
fig. 10 is a plan view of a variant of the flexible printed circuit;
fig. 11 is a three-dimensional view of a reel of light strip before the resin coating step;
fig. 12 is an enlarged three-dimensional view of a part of fig. 11;
fig. 13 is a three-dimensional view of a variant of the light strip;
fig. 14 is a cross-section view of the light strip of fig. 13;
fig. 15 is a three-dimensional view relating to an example of three-dimensional bending of the present light strip;
fig. 16 is an enlarged three-dimensional view of a part of fig. 15.

We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.
To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

DESCRIPTION OF SOME EMBODIMENTS

We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings, by way of a non-limiting illustration. The phraseology and terminology used here is also for the purposes of providing non-limiting examples.
With reference to the attached drawings, see in particular figs. from 1 to 6, a light strip 10 comprises: a flexible printed circuit 11 provided with a series of supports 12; one or more light sources 13 positioned on the supports 12; a profile 14 for containing the flexible printed circuit 11; and a cover 15. The flexible printed circuit 11 develops along a longitudinal axis of symmetry Y and fins 17 extend on both sides of the circuit 11 and are made in one piece with the supports 12.
The supports 12 are reciprocally distanced by means of interruptions 16 and electrically connected by means of a plurality of fins 17 which are positioned at the side of the printed circuit 11, substantially outside the transverse dimension of the supports 12. The fins 17 are made in one piece with the supports 12. Please see for example fig. 7, fig. 10 and fig. 12. Ultimately, a single flexible printed circuit 11 is therefore provided, provided with the fins 17 and the supports 12.
Preferably, the flexible printed circuit 11 is substantially flat, and the supports 12 and the fins 17 have the same thickness.
In fig. 1, fig. 2, fig. 4 and fig. 5, in a lower part of the present light strip 10, the profile 14 has been deliberately removed, so as to show the fins 17 more clearly. Naturally, the profile 14 extends for the entire length of the flexible printed circuit 11, therefore there are no uncovered segments. Furthermore, in figs. 1, 2, 4 and 5 the cover 15 has also been omitted.
At least some of the supports 12 - made of electrically conductive material or comprising at least one layer of electrically conductive material - have holes 18 configured to accommodate the contacts of a normal connector for the electric power supply. The holes 18 are distributed along the entire extension of the flexible printed circuit 11, so that the light strip 10 can be cut to the desired length.
In figs. from 1 to 14 the light strip 10 is provided with a row of fins 17 on each side of the flexible printed circuit 11, while figs. 15 and 16 show a longitudinal section along the center line.
The fins 17 of a same row are positioned on a plane P1 which is substantially orthogonal to a plane P2 on which the flexible printed circuit 11 lies. Therefore, the light strip 10 can have a substantially U-shaped cross-sectional shape, as shown in fig. 3 or fig. 6.
Alternatively, the fins 17 can be slightly inclined with respect to the direction orthogonal to the plane P2, as shown in fig. 12, fig. 13 and fig. 14, therefore the light strip 10 can be substantially V-shaped or trapezoidal-shaped.
The fins 17 can be made with any conformation whatsoever; however, in order to give a symmetrical shape to the connection between two supports 12, guaranteeing flexibility and resistance, they can have an arched shape, for example semicircular, semielliptical or suchlike, please see fig. 2, fig. 5 fig. 7, fig. 12, fig. 13 for example, or comprise a plurality of rectilinear segments, or a combination of rectilinear and curved segments, as shown in fig. 10 for example.
The interruptions 16 are preferably positioned at a constant pitch Y1 along the longitudinal extension of the circuit 11, therefore along the axis of symmetry Y, so that they are reciprocally equidistant, as in fig. 7 or fig. 10 for example.
The fins 17 are also positioned at a constant pitch Y2 along the extension of the circuit 11, therefore along the axis of symmetry Y, so that they are reciprocally equidistant, as in fig. 7.
The fins 17 located on one side of the circuit 11 mirror the fins 17 located on the opposite side, please see the two fins 17a and 17b of fig. 7 for example, thus guaranteeing a more uniform behavior of the light strip 10 during the bending operations.
In the variant of the present light strip 10 shown in fig. 13 and fig. 14, inside the profile 14, in particular on each of the opposite lateral walls 21, there is provided a tooth 22 configured to allow a mechanical coupling of the fins 17 with the profile 14. The tooth 22 substantially allows the snap-in insertion of the circuit 11 inside the profile 14. The tooth 22 comprises, at the upper part, an inclined plane 23 which facilitates the insertion of the circuit 11 in the support 14 and, at the lower part, an abutment surface 24 for the fins 17. The tooth 22 preferably extends on each of the lateral walls 21 for the entire extension of the profile 14.
The mechanical coupling between the fins 17 and the profile 14 allows to improve the resin coating step to create the cover 15, and also to possibly eliminate the adhesive on the lower surface. During the resin coating the tooth 22 in fact prevents any incoming air from lifting the circuit 11, thus creating shadows in the final light strip 10, therefore a photometric improvement in the light emission is also achieved.
The presence of the fins 17 distributed along the length of the circuit 11 gives the strip 10 the ability to twist and flex on several planes in space, thus allowing to mold the strip 10 in a three-dimensional direction on the basis of the specific applications. Please see fig. 15 and fig. 16, for example.
Furthermore, the fins 17 allow to possibly maintain a fixed center-distance between the various supports 12, without the need for work to be carried out on the strip 10.
Thanks to its flexibility and resistance, the light strip 10 can be wound in a reel and unrolled and cut, if necessary, as a function of the uses for which it is intended.
The circuit 11 can be manufactured by means of any technology currently available.
A rigid support can possibly be added to the circuit 11 if required by the uses for which it is intended, for example as a support for optics that require particular strength. By way of example, figs. from 4 to 6 show light sources 13 provided with optics 20.
The flexible printed circuit 11 comprises the supports 12 and the fins 17 in a single body. The circuit 11 can advantageously be printed on flat sheets in the form of a plurality of pre-cut portions, wherein each portion comprises a plurality of supports 12 connected by respective fins 17. The pre-cut portions can be removed from the sheet simply and quickly, and be assembled one to the other at respective ends in order to obtain a circuit 11 of the desired length.
The light source 13 can consist of LEDs or OLEDs, or another type of comparable or similar source.
Other components can also be added to the support 12 in order to meet specific project requirements, for example regulators, converters, BCRs, capacitors, optics, resistors and any other electronic/electrical component whatsoever.
The profile 14 for containing the flexible printed circuit 11 is preferably made of soft material, for example thermoplastic material. The profile 14, possibly provided with teeth 22, can be obtained by means of extrusion or also other technologies, such as casting, molding or other.
The profile 14 can be advantageously wound in a reel 19 and be unrolled when the flexible printed circuit 11 is inserted therein.
The cover 15 is obtained by casting a liquid element inside the profile so as to cover the flexible printed circuit 11 and guarantee a high degree of protection. The resin can arrive, at the upper part, flush with the profile 14. This resin ensures a high electrical insulation, making the strip suitable to also be applied outdoors.
The present invention also concerns a method for manufacturing the light strip 10, comprising the following steps:

preparing a flexible printed circuit 11 which develops along a longitudinal axis of symmetry Y and is provided with a series of supports 12 located in sequence and reciprocally distanced by means of interruptions 16, and electrically connected by means of a plurality of fins 17 which are positioned on both sides of the circuit 11 and are made in one piece with the supports 12;
inserting the flexible printed circuit 11 equipped with the supports 12 and the fins 17 in an open or semi-open containing profile 14;
inserting a resin in the profile 14 by means of casting, thus obtaining a protective cover 15 of the light strip 10.

In an initial situation, such as in fig. 7 or fig. 10, the fins 17 can be substantially coplanar to the supports 12 of the circuit 11.
The fins 17 are then bent toward the inside of the light strip 10, that is, toward the flexible printed circuit 11, so that they are disposed on a plane P1 that is orthogonal, as in fig. 3, or inclined, as in fig. 12, fig. 13, fig. 14, with respect to the plane P2 on which the circuit 11 lies.
Ultimately, the light strip 10 can be advantageously curved in a three-dimensional way, thanks to the presence of the fins 17 which connect the supports 12 separated by suitable interruptions 16.
In a "standard" flat circuit currently on the market, it would not be possible to obtain a three-dimensional curvature of the circuit itself because this would be damaged if curved on an unsuitable plane. Furthermore, in traditional circuits there is a need for external elements such as cables, supports, connectors, or for complex work that uses equipment or machines that are very precise from a mechanical point of view, in order to obtain a uniform pitch between the elements being worked.
In manufacturing the strip 10 the equipment or machines are much simpler, since the flexible printed circuit 11 can be applied to the profile 14 manually or with a simple winder, as if it were an adhesive tape, and in any case either before or after insertion in suitable templates where the resin coating occurs.
The light strip 10 is also substantially free from rigid supports and therefore can be curved following even very small radii of curvature, without risking damage to the flexible printed circuit 11 or the resin. By means of the strip 10 it is therefore possible to create wide or narrow curvatures in a three-dimensional space, maintaining its integrity and efficiency.
It is clear that modifications and/or additions of parts and steps may be made to the light strip and to the corresponding manufacturing method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of light strip, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.
In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the same claims.

Claims

Light strip (10) comprising: a flexible printed circuit (11) contained by a profile (14), provided with a series of supports (12) located in sequence with respect to each other which accommodate one or more light sources (13) and a cover (15), said supports (12) are reciprocally distanced by means of interruptions (16) and electrically connected by means of a plurality of fins (17) positioned at the side of said circuit (11), characterized in that said flexible printed circuit (11) develops along a longitudinal axis of symmetry (Y) and said fins (17) extend on both sides of said circuit (11) and are made in one piece with said supports (12).
Light strip (10) as in claim 1, characterized in that said fins (17) are positioned on a plane (P1) which is substantially orthogonal or slightly inclined with respect to a plane (P2) on which said circuit (11) lies.
Light strip (10) as in any claim hereinbefore, characterized in that said fins (17) have the shape of an arc or suchlike.
Light strip (10) as in any claim hereinbefore, characterized in that said interruptions (16) are positioned at a constant pitch (Y1) along the longitudinal extension of said circuit (11).
Light strip (10) as in any claim hereinbefore, characterized in that said fins (17) are positioned at a constant pitch (Y2) along the longitudinal extension of said circuit (11).
Light strip (10) as in any claim hereinbefore, characterized in that said fins (17) located on one side of said circuit (11) mirror the fins (17) located on the opposite side of said circuit (11).
Light strip (10) as in any claim hereinbefore, characterized in that said profile (14) comprises opposite lateral walls (21) provided with a tooth (22) which is configured to allow a mechanical coupling of said fins (17) with said profile (14).
Light strip (10) as in claim 7, characterized in that said tooth (22) comprises, at the upper part, an inclined plane (23) which facilitates the insertion of said circuit (11) in said support (14) and, at the lower part, an abutment surface (24) for said fins (17).
Light strip (10) as in claim 7 or 8, characterized in that said tooth (22) extends on each of said lateral walls (21) for the whole extension of said profile (14).
Method for manufacturing a light strip (10), comprising the following steps:
- preparing a flexible printed circuit (11) which develops along a longitudinal axis of symmetry (Y) and is provided with a series of supports (12) located in sequence and reciprocally distanced by means of interruptions (16), on which there are positioned one or more light sources (13) electrically connected by means of a plurality of fins (17) which are positioned on both sides of said circuit (11) and are made in one piece with said supports (12);

- inserting said circuit (11) equipped with said supports (12) and said fins (17) in an open containing profile (14);

- inserting a resin in said profile (14), thus obtaining a protective cover (15) of the light strip (10).
Method as in claim 10, characterized in that said fins (17) are bent toward the inside of the light strip (10), that is, toward said flexible printed circuit (11), in such a way that they are disposed on a plane (P1) substantially orthogonal or slightly inclined with respect to a plane (P2) on which the flexible printed circuit (11) lies.