WO2018172700A1

WO2018172700A1 - Led filament and lighting line with led filaments

Info

Publication number: WO2018172700A1
Application number: PCT/FR2018/050687
Authority: WO
Inventors: Marc Pettmann
Original assignee: Led-Ner
Priority date: 2017-03-24
Filing date: 2018-03-21
Publication date: 2018-09-27
Also published as: FR3064337B1; FR3064337A1

Abstract

An LED filament (1) comprising a substrate (2), light emitting diodes (3) distributed in at least one row over an upper face (24) of the substrate, an enclosure (4) made of transparent material containing fluorescent particles and covering the diodes, a male anode connector (61) and a male cathode connector (62) disposed on a first end (21) of the substrate and fixed on its lower face (23), and a female anode connector and a female cathode connector disposed on a second end of the substrate and fixed on its lower face, where the male connectors and the female connectors are a male-female combination. This structure of LED filament allows two LED filaments to be connected end-to-end while minimising, and preferably while avoiding, a non-emissive dark zone between the two LED filaments.

Description

LED filament and LED filament light line

The present invention relates to an LED filament, as well as to a lighting device comprising a plurality of LED filaments connected end to end to form a lighting line.

The present invention finds a preferred application, but not limited to, in the field of shop window and shelf lighting, as well as the field of lighting in the hotel and restaurant sector.

The invention also finds applications for chandeliers or designer lights, as well as for outdoor uses and in wet or even underwater environment, such as in the boating or outdoor architecture sector.

In these different areas, and more particularly in the lighting of shop windows and shelves, it is important to provide a very high quality lighting of light, which results in a high IRC (color rendering index) index. that is at least greater than 90.

The invention therefore proposes to use LED filaments as light sources which are adapted to be connected end-to-end.

A conventional LED filament is known from the patent application

US 2014/0369036 A1, wherein the LED filament comprises a substrate in the form of an elongated flat bar or rod, a plurality of light-emitting diodes regularly distributed in line on the substrate, an envelope overmolded at least around the diodes and realized in a transparent material containing fluorescent particles, and metal electrodes respectively forming the anode and the cathode of the LED filament, where these electrodes are fixed on the substrate and protrude from the envelope.

The state of the art can also be illustrated by the teachings of documents WO 2016/162616, US 2015/0070871, US 2014/0375201, US 2013/0141892, US 2015/0003039, CN 204099964 and CN 1041 10632, which also disclose LED filaments in which the electrodes protrude from a transparent envelope covering the light-emitting diodes mounted on a substrate.

Conventionally with the LED filaments disclosed in these prior documents, to connect two LED filaments end to end to form a lighting line, it is known and necessary to connect by welding, possibly with an electrical connection wire, the electrodes of the LED filaments; the connection can be in series or in parallel depending on the desired wiring.

Thus, when the LED filaments are connected end to end, it is noted the presence of a non-emissive dark zone between the two LED filaments, due to the spacing imposed by the electrodes between the two LED filaments.

The object of the present invention is to solve the aforementioned drawback by proposing an LED filament structure which makes it possible to connect two LED filaments end-to-end while minimizing, and preferably while avoiding, a non-emissive dark zone between the two filaments. LED, to form a lighting line based on LED filaments connected end to end and which has a continuity in the light emission along the line of illumination.

For this purpose, it proposes an LED filament comprising:

an elongated substrate along a longitudinal axis, having an opposite lower face and an opposite face, and first and second opposite ends;

a plurality of light-emitting diodes distributed in at least one row on the upper face of the substrate;

a transparent material envelope containing fluorescent particles and covering the light-emitting diodes; and

at least one anode connector and at least one cathode connector electrically connected to the light-emitting diodes;

such an LED filament being remarkable in that it comprises:

a first anode connector and a first cathode connector disposed on the first end of the substrate and fixed on the underside of the substrate;

a second anode connector and a second cathode connector disposed on the second end of the substrate and fixed on the underside of the substrate;

and or

one of the first anode connector and the second anode connector is in the form of a male anode connector protruding from the first or second corresponding end of the substrate along the longitudinal axis, while the other of the first anode connector and the second anode connector is in the form of a female anode connector not extending beyond the first or second corresponding end of the substrate along the longitudinal axis;

one of the first cathode connector and the second cathode connector is in the form of a male cathode connector protruding from the first end or second corresponding end of the substrate along the longitudinal axis, while the other the first cathode connector and the second cathode connector is in the form of a female cathode connector not extending beyond the first or second corresponding end of the substrate along the longitudinal axis;

so that the first anode connector and the second anode connector are electrically connected and complementarily male / female, and the first cathode connector and the second cathode connector are electrically connected and complementarily male / female.

Thus, thanks to the invention, it is easy to electrically connect two LED filaments placed end to end. Indeed, considering two adjacent LED filaments, it is sufficient to connect the first anode connector and the first cathode connector of an LED filament respectively to the second anode connector and the second cathode connector of the adjacent LED filament, for a parallel connection of the two LED filaments adjacent.

To do this, the connections are made by male / female cooperation between male connectors and female connectors, thereby mechanically making reliable the junction between the LED filaments and also allowing the two LED filaments to be very close, or even in contact, which will help to avoid a non-emissive dark zone between the two LED filaments and thus to obtain a continuity in the light emission along the LED filaments.

In addition, the interconnection between the adjacent LED filaments is easily achieved, without the need for interconnect wires (that is, wiring outside the LED filaments) that would flow alongside or between the LED filaments, ensuring easy assembly and effective.

In a particular embodiment, the male anodic connector and the male cathode connector are disposed on the first end of the substrate, while the female anodic connector and the female cathodic connector are disposed on the first end of the substrate. Alternatively, the male anodic connector and the female cathode connector are disposed on the first end of the substrate, while the female anodic connector and the male cathode connector are disposed on the first end of the substrate.

According to a variant, the LED filament comprises a plurality of blue light-emitting diodes, possibly with light-emitting diodes of another color.

According to one variant, the LED filament comprises a plurality of blue and red light-emitting diodes.

According to a variant, the envelope is made in a gel or transparent colloidal material containing fluorescent particles, and in particular phosphorus particles.

According to one variant, the light-emitting diodes are of the LED chip (or "LED chip") type, and in particular of the LED chip type on printed circuit board (or "COB (Chip On Board) LEDs").

According to one variant, the substrate has a thickness of between 0.1 and 1 millimeter.

According to one variant, the substrate has a length, along the longitudinal axis, of between 10 and 150 millimeters.

According to one variant, the substrate has a width, in a direction orthogonal to the longitudinal axis, of between 1 and 5 millimeters.

According to one feature, the female connectors are flush with the first end or second corresponding end of the substrate along the longitudinal axis. In other words, the female connectors are in alignment with the corresponding end of the substrate.

In a particular embodiment, in the array, the light-emitting diodes are regularly distributed along the longitudinal axis with a regular main longitudinal spacing between each light-emitting diode, and furthermore:

- considering a first longitudinal gap between the first end of the substrate and a first light-emitting diode which is the light-emitting diode closest to said first end along the longitudinal axis, said first longitudinal gap is between 0.25 and 0, 75 times the main longitudinal spacing of the row; and - considering a second longitudinal gap between the second end of the substrate and a last light-emitting diode which is the light-emitting diode closest to said second end along the longitudinal axis, said second longitudinal gap is between 0.25 and 0, 75 times the main longitudinal spacing of the row.

Thus, once two LED filaments are connected end to end, the longitudinal spacing between the first light emitting diode of one LED filament and the last LED of the other LED filament will be substantially equivalent to the sum of the first longitudinal spacing. and the second longitudinal spacing, being in the order of 0.5 to 1.5 times the main longitudinal spacing of the row. Thanks to this embodiment, there will be no or almost no spacing gap between the light emitting diodes from one LED filament to the other LED filament, thus contributing to a continuity in the light emission along the LED filaments.

Advantageously, the first longitudinal spacing is between 0.4 and 0.6 times the main longitudinal spacing of the row, and the second longitudinal spacing is between 0.4 and 0.6 times the main longitudinal spacing of the row. .

Thus, once two LED filaments are connected end to end, the longitudinal spacing between the first light emitting diode of one LED filament and the last light emitting diode of the other LED filament will be of the order of 0.8 to 1, 2 times the main longitudinal spread of the row.

Alternatively, the first longitudinal gap is equivalent to 0.5 times the main longitudinal spacing of the row, and the second longitudinal gap is equivalent to 0.5 times the main longitudinal spacing of the row.

Thus, once two LED filaments are connected end to end, the longitudinal gap between the first light emitting diode of one LED filament and the last LED of the other LED filament will be equivalent to the main longitudinal spacing of the LED. row.

In a first embodiment, the LED filament comprises:

a first connection element disposed on the first end of the substrate, fixed on the underside of the substrate and not extending beyond the first end of the substrate along the longitudinal axis, where said first end of the substrate connecting element comprises a first anodic conducting portion and a first cathodic conducting portion separated by an insulator;

a second connection element disposed on the second end of the substrate, fixed on the underside of the substrate and not extending beyond the second end of the substrate along the longitudinal axis, where the said second connection element comprises a second conductive part; anode and a second cathodic conducting portion separated by an insulator;

and or :

the male anodic connector comprises a conductive anodic pad mounted in a hole formed in one of the first anode conductive part and the second anodic conducting part, and the female anodic connector comprises a hole formed in the other of the first part. anodic conductor and the second anodic conductive portion; and

the male cathode connector comprises a conductive cathode pad mounted in a hole in one of the first cathodic conducting portion and the second cathodic conducting portion, and the female cathodic connector comprising a hole formed in the other of the first portion cathode conductor and the second cathodic conductive portion.

Thus, the electrical - and mechanical - connection between two LED filaments is carried out by engaging the conductive pads in two holes at the same time, contributing to a simplification and industrialization of the manufacture, being nevertheless reminded that the invention relates to LED filaments whose dimensions are particularly small and well below those of conventional tube lamps.

According to a variant, the first connection element is flush with the first end of the substrate along the longitudinal axis.

Alternatively, the second connection member is flush with the second end of the substrate along the longitudinal axis.

According to one possibility, the holes formed in the first anodic conducting portion and the first cathodic conducting portion of the first connecting element have a first transverse spacing in a direction orthogonal to the longitudinal axis, the holes formed in the second anodic conducting portion and the second cathodic conducting portion of the second connecting member has a second transverse gap in a direction orthogonal to the longitudinal axis, and the first transverse gap is different from the second transverse gap. Thus, when the conductive pads are engaged both in the holes with a first transversal spacing of an LED filament and in the holes with a second transverse spacing of another LED filament, this difference in spacing will contribute to a mounting in strength of conductive pads, and therefore to a mechanical strength and electrical contact increased and durable.

Advantageously, the conductive anodic pad and the conductive cathode pad each have two opposite frustoconical ends.

In a second embodiment, the LED filament comprises: a first connection element disposed on the first end of the substrate, fixed on the underside of the substrate, wherein said first connection element comprises a first anode conductive part and a first part. cathodic conductors separated by an insulator;

a second connection element disposed on the second end of the substrate, fixed on the underside of the substrate, wherein said second connection element comprises a second anodic conducting portion and a second cathodic conducting portion separated by an insulator;

and or :

the first anode connector is a male connector formed at one end of the first anodic conducting portion projecting longitudinally from the first end of the substrate along the longitudinal axis, and the first cathode connector is a male connector formed of a end of the first cathodic conducting portion projecting longitudinally from the first end of the substrate along the longitudinal axis; and

the second anode connector is a female connector formed of a notch formed in one end of the second anodic conducting portion which does not protrude from the second end of the substrate along the longitudinal axis, and the second cathode connector is a connector female formed a notch formed in one end of the second cathodic conducting portion which does not protrude from the second end of the substrate along the longitudinal axis.

According to one possibility, the LED filament comprises a connection device fixed on the underside of the substrate, extending over the entire length of the substrate from its first end to its second end, said connection device comprising an anode conductive part and a cathodic conducting portion separated by an insulator, and the first connecting element constitutes a first end portion of the connection device and the second connecting element constitutes a second end portion of the connection device.

Thus, the first holes (which are the holes formed in the first anodic conducting portion and the first cathodic conducting portion of the first connecting element) are formed on the first end portion of the connection device, and the second holes (which are the holes formed in the second anodic conducting portion and the second cathodic conducting portion of the second connecting element) are formed on the second end portion of the connection device.

According to one characteristic, the anodic conducting portion and the cathodic conducting portion are conducting sections of constant cross section; the cross section being a section along a transverse plane orthogonal to the longitudinal axis.

According to one variant, the conducting profiles are of cross-section in the form of a circle sector at right angles, so that the connection device has a semicircular cross-section.

Advantageously, the holes are drilling holes, the drilling technique being the most suitable for the small transverse dimensions of the filament LED less than 5 millimeters. In addition, the drilling technique allows the holes to be made with separate spacings, as described above.

In a particular embodiment, the first anode connector, the first cathode connector, the second anode connector and the second cathode connector are electrically connected to the light emitting diodes by means of vias (eg plated holes) passing through the substrate.

According to one possibility, the LED filament comprises an anodic lower track and a cathodic lower track fixed on the underside of the substrate and electrically connected to the light emitting diodes, and wherein the first anode connector and the second anode connector are fixed on the underside of the substrate. by being in contact with the anodic lower track, and the first cathode connector and the second cathode connector are fixed on the underside of the substrate in contact with the lower cathode track. According to one variant, the LED filament further comprises a current regulator mounted on the substrate and molded by the envelope, where the or each row of diodes is connected to a current regulator in order to allow a regulated current supply of the or each row.

In this way, the or each current regulator ensures a substantially constant current in the or each row of diodes, thus answering a problem specific to the LED filaments.

In LED filaments, it is important that all diodes have the same threshold voltage (or forward voltage VF) to avoid overheating of the diodes and so that each diode provides the same light output. However, in the LED filaments, it is not uncommon for one or more diodes to be defective, in the sense that they do not have the required threshold voltage, thus causing problems of overheating and reliability.

Given the conditions of automatic and industrial manufacture of LED filaments, it is almost impossible to test each diode, except in time and cost prohibitive. It is therefore mandatory to consider that one or more diodes will be defective.

To solve this problem, the use of a current regulator will make it possible to supply a constant current for a given voltage range (for example from 20 to 36 volts) to diodes possibly having different threshold voltages, which will allow to parallel several rows of diodes, without risk of overheating and reliability, despite the possible presence of one or more defective diodes. It suffices to determine a constant regulated current for N rows of P diodes in series, the operating voltage varying with the same current in each diode.

The current regulator (s) guarantee a temperature stability of the diodes which makes them more reliable, since these diodes will be fed with a constant current source, so that when the temperature increases at constant current, the power of the filament decreases and we obtain thus an intrinsic thermal regulation for each diode.

The fact of positioning one or more current regulators will also make it possible to overcome the disparities in threshold voltages between LED filaments of a lighting device, thus avoiding a single overheating in the same lighting device.

Finally, in the event of a failure of the power source (on voltage), the failure of one of the components of the or each regulator of current allows to locate the segment in question either by becoming ineffective (highlighting of the diodes) or by opening the circuit (extinction of the diodes) without causing edge effects on the other interconnected LED filaments.

According to one variant, the diodes are distributed in several rows of diodes in series, the diodes of each row being connected sequentially one after the other and in series and the rows being connected in parallel, where each row is connected to a current regulator.

It is understood that this parallel distribution of rows of diodes relates to an electrical paralleling rows of diodes. However, the diodes can be geometrically distributed linearly or rectilinearly on the substrate; only the electrical wiring of the diodes conferring the electric paralleling rows of diodes.

It should be noted that the LED filament may comprise:

a single current regulator for all rows of diodes, or

at least two current regulators so that each current regulator is shared with several rows of diodes, or

- as many current regulators as rows of diodes so that each row of diodes has its own current regulator.

According to a variant, the LED filament further comprises an AC / DC converter (otherwise called a rectifier) mounted on the substrate, molded by the envelope and connected to one or each row start diode in order to allow a power supply of the or each row from an alternative source. It should be noted that such an AC / DC converter could be connected externally to the LED filament, between the AC source and the filament LED connectors.

The invention also relates to a lighting line comprising at least two LED filaments according to the invention, wherein these LED filaments are arranged in alignment along their respective longitudinal axes and are connected end to end, these LED filaments comprising at least one filament LED upstream and a downstream LED filament interconnected with the first anode connector and the first cathode connector of the upstream LED filament connected by male / female cooperation respectively to the second anode connector and to the second cathode connector of the adjacent downstream LED filament for a parallel connection of the filament LED upstream and downstream adjacent LED filament, and where the first end of the upstream LED filament substrate is spaced from the second end of the downstream LED filament substrate along their longitudinal axes with a longitudinal clearance of less than 2 millimeters.

Thus, and as explained above, the LED filaments are aligned, offering a particularly limited space and providing continuity (or near-continuity) in the light emission along the LED filaments. The invention also offers the possibility of providing lighting lines of the desired overall length.

According to a possibility of the invention, the longitudinal clearance is less than 1 millimeter. Advantageously, the longitudinal clearance is less than 0.5 millimeters.

According to another possibility, the first end of the substrate of the upstream LED filament is in contact with the second end of the substrate of the downstream LED filament. In other words, the longitudinal clearance is zero.

If the ends of the substrates are covered in part by the envelope, the first end of the substrate of the upstream LED filament is in contact with the second end of the substrate of the downstream LED filament with a contact between the envelopes of these two ends at the level of the junction.

Other characteristics and advantages of the present invention will appear on reading the detailed description below, of non-limiting implementation examples, with reference to the appended figures in which:

FIGS. 1 to 7 are schematic views illustrating several successive steps for manufacturing an LED filament according to a first embodiment of the invention (hereinafter referred to as the first LED filament), with:

- In Figure 1 is illustrated a first step of manufacturing the substrate assembly with the light emitting diodes mounted and electrically connected to the substrate;

- In Figure 2 is illustrated a second step of laying the envelope on the light emitting diodes;

- Figure 3 is illustrated a third step of laying in a frame of the two conductive sections which will form the anode conductive portion and the cathode conductive portion of the connection device;

- Figures 4 and 5 is illustrated a fourth step of laying an insulator between the two conductive sections set on the frame, finalizing the manufacture of the connection device; - Figure 6 is illustrated a fifth step of fixing the connection device under the substrate;

- In Figure 7 is illustrated a sixth step of connecting the conductive pads in first holes formed at the first ends of the two conductive sections;

- Figure 8 is a schematic view of the first LED filament from the manufacturing steps illustrated in Figures 1 to 7;

FIG. 9 is a zoomed view of the zone IX of FIG. 8, at a distinct angle of view, illustrating the first end of the LED filament; FIG. 10 is a zoomed view of the area X of FIG. 8, at a distinct angle of view, illustrating the second end of the LED filament;

- Figure 1 1 is a schematic view of two first LED filament in the end-to-end interconnection phase;

FIG. 12 is a zoomed view of the area XII of FIG. 11, illustrating the ends of the first LED filaments which are in the interconnection phase;

FIG. 13 is a schematic view similar to that of FIG. 12, at the end of interconnection of the first LED filaments;

FIG. 14 is a partial schematic view of two LED filaments according to a second embodiment, illustrating their ends which are in the end-to-end interconnection phase, and where the envelopes are not illustrated;

FIG. 15 is a partial schematic view of two LED filaments according to a third embodiment, illustrating their ends which are in an end-to-end interconnection phase, and where the envelopes and the set of light-emitting diodes are not illustrated. ;

FIG. 16 is a partial schematic view of two LED filaments according to a fourth embodiment, illustrating their ends which are in the end-to-end interconnection phase, and where the envelopes are not illustrated.

The following description, with reference to FIGS. 1 to 13, relates to an LED filament 1 according to a first embodiment of the invention and hereinafter referred to as the first LED filament 1, as well as to its manufacturing method. Three other embodiments of an LED filament 1 according to the invention will also be described, with reference to FIGS. 14 to 16. In all of these figures, identical or similar references designate where appropriate, identical or similar elements, organs or groups of members.

The steps of the manufacturing method of the first LED filament 1 are described hereinafter with reference to FIGS. 1 to 7.

The first step illustrated in FIG. 1 consists in manufacturing an assembly comprising a substrate 2 on which a plurality of light-emitting diodes 3 are mounted and connected.

The substrate 2 is an elongate substrate along a longitudinal axis 29 and is in the form of an elongated flat bar or rod. The substrate 2 may be made of a flexible or rigid material, such as a ceramic or plastic material.

The substrate 2 has a first 21 and a second 22 opposite ends, and extends along said longitudinal axis 29 between its two ends 21, 22. The substrate 2 has two opposite faces 23 and 24 opposite respectively bordered by two longitudinal slices 25 respectively right and left opposite.

The length LO of the substrate 2 (measurement taken along the longitudinal axis between the two ends 21, 22) is between 10 and 150 millimeters. The thickness EP of the substrate 2 (measurement taken between the two faces 23, 24) is between 0.1 and 1 millimeter. The width LA of the substrate 2 (measurement taken between the longitudinal slices) is between 1 and 5 millimeters.

The diodes 3 are light-emitting diodes comprising blue diodes and possibly diodes in a color other than blue (such as, for example, red), which regularly distributed in one or more rows on the only upper face 24 of the substrate 2, the diodes 3 of a row being connected sequentially one after the other and in series.

The diodes 3 are of the LED chip (or "LED chip") type, and in particular of the LED chip type on printed circuit board (or "COB (Chip On Board) LEDs").

For the wiring of the diodes 3, conductive tracks are provided on the upper face 24 of the substrate 2, such as metallized tracks (eg made of copper) or tracks based on conductive ink; these conductive tracks can for example be made by printing.

The conductive tracks comprise in particular an anodic conducting track 31 and a cathodic conducting track 32 disposed of on both sides of the diodes 3, along the longitudinal slices 25 between the two ends 21, 22.

According to one possibility, the diodes 3 are distributed in a single row of diodes in series, in other words the diodes 3 are connected sequentially one after the other and in series.

At the level of the wiring for the or each row, the start-of-row diode 3 is connected to the anodic conducting track 31 and the end-of-row diode 3 is connected to the cathode conductor track 32. In a variant, the diodes 3 are distributed according to several rows of diodes in series, the diodes 3 of each row being connected sequentially one after the other and in series. The notion of "row" is here associated with the electrical connection of the diodes 3, and not with the geometric distribution of the diodes 3 on the substrate 2.

Thanks to the two conductive tracks 31, 32, it is easy to wire the diodes 3 into one or more rows of diodes 3 in series, these rows thus being in parallel electrical connection.

The wirings between the diodes 3 and the wirings between the conductive tracks 31, 32 and the diodes 3 can be made:

- according to a wire bonding technique called "wire bonding", employing soldered conductive wires, such as gold wires; and or

according to a so-called flip chip technique, by connecting the diodes to conductive connection tracks provided on the substrate 2.

At the level of the geometric disposition of the diodes 3, the latter can advantageously all be placed linearly one after the other, along the longitudinal axis 29 of the substrate 2, between its two ends 21, 22.

Over the length of the substrate 2, the diodes 3 are evenly distributed along the longitudinal axis 29 with a regular longitudinal main ELP spacing.

Considering a first longitudinal gap EC1 between the first end 21 of the substrate 2 and a first diode 3 which is the diode 3 closest to this first end 21 along the longitudinal axis 29 (see FIG. 1), this first EC1 longitudinal gap is between 0.4 and 0.6 times the main longitudinal ELP gap. Similarly, considering a second longitudinal gap EC2 between the second end 22 of the substrate 2 and a last diode 3 which is the diode 3 closest to this second end 22 along the longitudinal axis 29 (see Figure 10) , this second longitudinal gap EC2 is equivalent to the first longitudinal gap EC1 and is therefore between 0.4 and 0.6 times the main longitudinal spacing ELP.

It can also be provided to use at least one current regulator connected to the row start diodes 3, to the end of row diodes 3 and also connected between the anodic conducting track 31 and the cathode conductor track 32; the or each current regulator being provided to allow a regulated current supply of each row of diodes 3 in series. Alternatively or in addition to the current regulator, it may be provided to use, in each row of diodes, a balancing resistor 33 for current balancing in each row of diodes 3.

It is conceivable to provide a current regulator for each row, in other words each row comprises a current regulator followed by a plurality of diodes 3 in series, where the rows are in parallel. Such a current regulator 3 would be connected to the starting diode 3 of the corresponding row, to the end diode 3 of the corresponding row and also connected between the anodic conducting track 31 and the cathodic conducting track 32.

As a variant, it is conceivable to provide a single current regulator connected to each start-of-row diode 3, to each end-of-row diode 3 and also connected between the anodic conducting track 31 and the cathodic conducting track 32. In other words, the current regulator would be placed upstream of the set consisting of several rows in parallel, each row comprising diodes in series with possibly a current balancing resistor 33.

The or each current regulator can be realized in the form of a circuit integrating two resistors and two transistors, or it can be realized in the form of other types of circuit known in the field of regulation, or in the form of an electronic component.

Although not visible in the figures, lower conductive tracks are also provided on the lower face 23 of the substrate 2, such as metallized tracks (eg made of copper) or ink-based tracks. conductive; these conductive tracks can for example be made by printing.

These lower conductive tracks include:

an anodic lower track electrically connected to the anodic conducting track 31 provided on the upper face 24, and

a lower cathodic track electrically connected to the cathodic conducting track 32 provided on the upper face 24.

These lower conductive tracks are connected to the tracks 31, 32 by means of:

or vias traversing the substrate 2 in its thickness,

or of conductive lateral tracks passing through the longitudinal slices.

These lower conductive tracks are disposed on either side of a median plane extending along the longitudinal axis 29 between the two longitudinal slices.

The second step illustrated in FIG. 2 consists in depositing on the upper face 24 of the substrate 2 and on the diodes 3 a casing 4 made of transparent material containing fluorescent particles and covering the diodes 3.

The envelope 4, placed over the entire width and over the entire length of the substrate 2, forms a layer which is made of a gel or transparent colloidal material containing fluorescent particles, and in particular particles of phosphorus.

The envelope 4 has a cross-section in the form of a semicircle or circular segment, and it has a maximum thickness EM (at the right of the diodes 3) of between 1 and 5 millimeters.

It is conceivable to deposit the envelope 4 with a simple deposition, or with a double deposition or even a multiple deposition.

The lower face 23 of the substrate 2 is in turn not covered by the envelope 4 or at least, if it is partially covered, the envelope 4 will not cover the lower conductive tracks mentioned above. The envelope 4 may also cover, at least partially, the longitudinal slices of the substrate 2 and / or the ends 21, 22 of the substrate 2.

The third step illustrated in FIG. 3 consists in positioning two sections 51, 52 conductors, in particular metal profiles, in a groove 90 of a frame 9, where the profile 51 will form an anode profile and the profile 52 form a cathode profile.

These profiles 51, 52 are of constant cross section, and in particular of cross section in the form of angular sector at right angles (or angle of 90 degrees). These profiles 51, 52 are identical, and they have a length equivalent to the length LO of the substrate 2.

The groove 90 is of semicircular section, and the two sections 51, 52 are complementary to the groove 90. Inside the groove 90, the sections 51, 52 are not in contact and are separated from each other. the other through a gap 53 defining a transverse spacing AND.

Each section 51, 52 has first and second opposite ends. The first ends of the sections 51, 52 are planar and coplanar ends, and the second ends of the sections 51, 52 are also planar and coplanar ends.

A first hole 51 1 is formed in the first end of the anode section 51 and a second hole 512 is formed in the second end of the anode section 51. A first hole 521 is formed in the first end of the cathode profile 52 and a second hole 522 is formed in the second end of the cathode profile 52.

These holes 51 1, 512, 521, 522 are drilling holes all having the same diameter, this diameter being between 0.1 and 0.25 times the width LA of the substrate 2. For example, these holes 51 1, 512, 521, 522 have a diameter of between 0.3 and 0.8 millimeters, and especially between 0.4 and 0.6 millimeters.

These holes 51 1, 512, 521, 522 are centered around axes of drilling parallel to the longitudinal axis 29 in final situation on the LED filament 1. These holes 51 1, 512, 521, 522 have a depth greater than or equal to 7 millimeters, and in particular greater than or equal to 10 millimeters, or even between 7 and 15 millimeters.

In the situation on the LED filament 1, the first holes 51 1, 521 have a first transverse spacing ET1 in a direction orthogonal to the longitudinal axis 29 (see FIG. 6), and the second holes 512, 522 have a second transverse spacing ET2 (see Figure 10) in a direction orthogonal to the longitudinal axis 29, and the first transverse spacing ET1 is different from the second transverse spacing ET2. In FIGS. 6 and 10, these transverse spacings ET1, ET2 correspond to the edge-to-edge distances, but could also have been considered the distances between the axes of drilling.

The fourth step illustrated in FIGS. 4 and 5 consists in positioning an insulator 54 inside the interstice 53, and insulator 54 forming a layer of thickness equivalent to the transverse spacing ET, and extending over the entire length. profiles 51, 52 and also over the entire height (or depth) of the gap 54, for the purpose of electrically isolating the two sections 51, 52.

The insulator 54 is made of an electrically insulating material, and in particular an elastically flexible or flexible material.

This insulation 54 is fixed on the two sections 51, 52 (or between the two sections 51, 52), in particular by gluing.

Once the insulation 54 fixed on the two sections 51, 52, they together form a connection device 5, which has a planar upper face, since the sections 51, 52 and the insulator 54 have coplanar flat top faces; this planar upper face of the connection device 5 having a width LD equivalent to the width LA of the substrate 2.

This connection device thus comprises two conductive parts separated by the insulator 54, namely an anodic conducting portion consisting of the anode profile 51 and a cathodic conducting portion consisting of the cathode profile 52.

The fifth step illustrated in FIG. 6 consists in fixing the flat upper face of the connection device 5 on the lower face 23 of the substrate 2, so that the connection device 5 extends over the entire length of the substrate 2 from its first end. 21 to its second end 22 and across the entire width of the substrate 2 from one slice 25 to the other slice 25.

The LED filament 1 will thus have a substantially circular cross-section of diameter substantially equivalent to the width LA of the substrate 2. Such an LED filament 1 can thus advantageously be inserted into a transparent hollow tube whose internal diameter is substantially greater than this width LA, so that the LED filament 1 is mounted fitted inside this transparent hollow tube.

Thus, the first ends of the profiles 51, 52 are in register (or coplanar) with the first end 21 of the substrate 2, and the second ends of the profiles 51, 52 are in registration (or coplanar) with the second end 22 of the substrate 2.

The connection device 5 is for example fixed by bonding on the lower face 23 of the substrate 2. This connection device 5 will have the function, in addition to allowing end-to-end connection between two LED filaments 1, to promote heat dissipation for the heat emitted by the diodes 3.

Although not visible, once the connection device 5 is fixed on the lower face 23 of the substrate 2, two electrical connections are established with the connection device 5, namely:

the anodic profile 51 establishes a direct electrical contact with the anode lower track provided on the lower face 23 of the substrate 2, so that this anode profile 51 is electrically connected with the anode conductive track 31 provided on the upper face 24 to connect the diodes 3; the cathode profile 52 establishes a direct electrical contact with the lower cathode track provided on the lower face 23 of the substrate 2, so that this cathode profile 52 is electrically connected with the cathode conductor track 32 provided on the upper face 24 to connect the diodes 3.

The sixth and final step illustrated in Figure 7 is to assemble:

an anode conductive pad 61 in the first hole 51 1 formed in the first end of the anode profile 51; and

a cathodic conductor pad 62 in the first hole 521 formed in the first end of the cathode profile 52.

Each conductive pad 61, 62 has a diameter substantially equivalent to the diameter of the holes 51 1, 512, 521, 522. Each conductive pad 61, 62 has two opposite frustoconical ends, that is to say with a decreasing diameter.

Thus, the first LED filament 1 has:

a first anode connector formed of the anode conductive pad 61 disposed on the first end 21 of the substrate 2 and fixed on the lower face 23 of the substrate 2, this anode conductive pad 61 being in the form of a male anode connector protruding from the first end 21 of the substrate 2 along the longitudinal axis 29; a first cathode connector formed of the cathodic conductive pad 62 disposed on the first end 21 of the substrate 2 and fixed on the lower face 23 of the substrate 2, this cathodic conductive pad 62 being in the form of a male cathode connector protruding from the first end 21 of the substrate 2 along the longitudinal axis 29;

a second anode connector formed by the second hole 512 formed in the second end of the anode profile 51 and thus disposed on the second end 22 of the substrate 2 and fixed on the lower face 23 of the substrate 2, this second hole 512 being in the form of a female anode connector not exceeding the second end 22 of the substrate 2 along the longitudinal axis 29;

a second cathode connector formed of the second hole 522 formed in the second end of the cathode profile 52 and thus disposed on the second end 22 of the substrate 2 and fixed on the lower face 23 of the substrate 2, this second hole 522 being in the form of a female cathode connector not extending beyond the second end 22 of the substrate 2 along the longitudinal axis 29.

More precisely, the second holes 512, 522 are in alignment with the second end 22 of the substrate 2.

Thus, the connection device 5 has:

a first end portion 501 which forms a first connection element disposed on the first end 21 of the substrate 2, fixed on the lower face 23 of the substrate 2 and not extending beyond the first end 21 of the substrate 2 along the longitudinal axis 29, where this first end portion 501 comprises a first anodic conducting portion (first end of the anode profile 51) and a first cathodic conducting portion (first end of the cathode profile 52) separated by the insulator 54, and the anode conductive pad 61 is mounted in the first hole 51 1 formed in this first anodic conducting portion (first end of the anode section 51) and the cathode conducting pad 62 is mounted in the first hole 521 formed in the first cathodic conducting portion (first end of the cathode profile 52);

a second end portion 502 which forms a second connection element disposed on the second end 22 of the substrate 2, fixed on the lower face 23 of the substrate 2 and not extending beyond the second end 21 of the substrate 2 along the longitudinal axis 29, where this second end portion 502 comprises a second anodic conducting portion (second end of the anode profile 51) and a second cathodic conducting portion (first end of the cathode profile 52) separated by the insulator 54, and wherein the second hole 512 is formed in this second anodic conducting portion (Second end of the anode section 51) and the second hole 522 is formed in this second cathode conductive portion (second end of the cathode profile 52).

In a non-illustrated variant, the first end portion 501 and the second end portion 502 form two distinct connecting elements, separated and fixed on the lower face 23 of the substrate 2 respectively on the first and the second ends 21, 22 of the substrate 2.

In a variant not illustrated:

- The anodic conductor pad 61 is mounted in the first hole 51 1 formed in the first end of the anode section 51; and

- The cathode conductor pad 62 is mounted in the second hole 522 formed in the second end of the cathode profile 52.

The coupling of two first LED filaments 1 is described hereinafter with reference to FIGS. 1 to 13, for the purpose of forming a lighting line comprising at least one upstream LED filament 1 (on the left in FIGS. ) and a downstream LED filament 1 (right in FIGS. 1 to 13) interconnected.

The two LED filaments 1 are arranged in alignment along their respective longitudinal axes 29 and are connected end to end with:

the anodic conducting pad 61, provided on the first end 21 of the substrate 2 of the upstream LED filament 1, which is inserted (or engages) inside the second hole 512 provided on the second end 22 of the substrate 2 of the downstream LED filament 1; and

the cathode conductor pad 62, provided on the first end 21 of the substrate 2 of the upstream LED filament 1, which is inserted (or engages) inside the second hole 522 provided on the second end 22 of the substrate 2 of the downstream LED filament 1.

Thus, these two first LED filaments 1 are interconnected in parallel, by male / female interactions between the two pads 61, 62 and the two holes 512, 522, according to tight adjustments, the flexibility of the insulators 54 and the difference in spacing between the holes allowing a good axial positioning and a strong mechanical strength. It is possible to promote or complete the junctions by adding conductive glue or welding points in the holes, prior to inserting the studs into the corresponding holes.

Once the two studs 61, 62 are well sunk into the two holes 512, 522, the first end 21 of the substrate 2 of the upstream LED filament 1 is spaced from the second end 22 of the substrate 2 of the downstream LED filament 1 along their axes. longitudinal members 29 of a longitudinal clearance JL (visible in FIG. 13) less than 1 millimeter, or even less than 0.5 millimeters, or even zero (in this case the first end 21 of the substrate 2 of the upstream LED filament 1 is in contact with of the second end 22 of the substrate 2 of the downstream LED filament 1).

Thus, the first diode 3 of the upstream LED filament 1 (which is the diode 3 closest to the first end 21 along the longitudinal axis 29) is spaced from the last diode 3 of the downstream LED filament 1 (which is the diode 3 closest to the second end 22 along the longitudinal axis 29) of a longitudinal spacing ED (visible in FIG. 13) which is equivalent to the sum of the first longitudinal spacing EC1, the second longitudinal spacing EC2 and of the longitudinal play JL, that is:

ED = EC1 + EC2 + J

With EC1 = EC2 = 0.5 ELP (ELP = main longitudinal gap) and with JL = 0 (zero longitudinal clearance), then ED = ELP, which results in a constant spacing between the diodes 3 by passing a filament LED 1 to another. In other words, the pitch between the diodes 3 is constant (or almost constant) in the LED filaments 1 and also at the junction between the LED filaments 1.

Figures 14 to 15 illustrate three other embodiments of an LED filament 1 according to the invention, which are distinguished essentially on the form of the interconnection means between the LED filaments.

The remainder of the description relates to the second embodiment of FIG. 14 and the third embodiment of FIG. 15 which are two rather similar modes.

In these second and third embodiments, the LED filament 1 comprises a first connection element 1501 disposed on the first end 21 of the substrate 2, fixed on the lower face 23 of the substrate 2, where this first connection element 1501 comprises:

a first anodic conducting portion formed of a first anode profile 151; a first cathodic conducting portion formed of a first cathode profile 152;

an insulator 154 separating the first anode profile 151 and the first cathode profile 152.

This LED filament also comprises a second connection element 1502 disposed on the second end 22 of the substrate 2, fixed on the lower face 23 of the substrate 2, where this second connection element 1502 comprises:

a second anodic conducting portion formed of a second anode profile 151 ';

a second cathodic conducting portion formed of a second cathode profile 152 '; and

an insulator 154 'separating the second anode profile 151' and the second cathode profile 152 '.

As in the case of the first LED filament 1, the first connection element 1501 can form a first end portion of a connection device which extends over the entire length of the second LED filament 1, and the second connection element 1502 may form a second end portion of this connection device, so that the first anode profile 151 and the second anode profile 151 'form a single anode profile, and the first cathode profile 152 and the second cathode profile 152 'form one and the same cathodic profile.

In these second and third embodiments, the LED filament 1 comprises:

a first male anodic connector 161 formed of one end of the first anode profile 151 projecting longitudinally from the first end 21 of the substrate 2 along the longitudinal axis 29;

a first male cathode connector 162 formed of an end of the first cathode profile 152 projecting longitudinally from the first end 21 of the substrate 2 along the longitudinal axis 29;

a second female anode connector 1512 formed of a notch formed in one end of the second anodic section 151 'which is in register (or coplanar) with the second end 22 of the substrate 2; and

- A second female cathode connector 1522 formed of a notch formed in one end of the second cathode profile 152 'which is in alignment (or coplanar) with the second end 22 of the substrate 2. The two male connectors 161, 162 are of complementary shape to the two female connectors 1512, 1522 so that they can fit into each other by male / female cooperation.

The end-to-end coupling of two LED filaments 1, according to these second and third embodiments, is carried out as follows:

the first male anode connector 161 of the upstream LED filament 1 is inserted (or engages) inside the second female anode connector 1512 of the downstream LED filament 1; and

the first male cathode connector 162 of the upstream LED filament 1 is inserted (or engages) inside the second female anode connector

1522 downstream LED filament 1.

As in the case of the first LED filament 1, by playing on a difference in spacing between the first male connectors 161, 162 and between the second female connectors 1512, 1522, the mechanical and electrical connection advantageously takes place in a close fit with a coupling in force.

The main difference between the LED filament 1 according to the second embodiment and the LED filament 1 according to the third embodiment is that:

in the second embodiment, the two male connectors 161, 162 are positioned on the inside and are spaced from each other only from the thickness of the insulator 154 which also protrudes to isolate these two male connectors 161, 162;

in the third embodiment, the two male connectors 161, 162 are positioned on the outside and are spaced from one another by a gap greater than the thickness of the insulator 154.

In the third embodiment, windows can be formed in the thickness of the substrate 2 so as to open into the two notches forming the female connectors 1512, 1522. Thus, once the male connectors 161, 162 inserted in these notches, it is possible to deposit, through these windows, points of conductive glue or metal weld points, to reinforce the mechanical supports and the electrical contacts of these male connectors 161, 162 within these slots.

In the fourth embodiment of Figure 16, the filament

LED 1 comprises a first connection element 2501 disposed on the first end 21 of the substrate 2, fixed on the lower face 23 of the substrate 2, where this first connecting element 2501 is a soldered male plug on the lower face 23 and comprising:

a first male anode connector 261;

a first male cathode connector 262;

an insulator 254 separating these two male connectors 261, 262.

This LED filament 1 also comprises a second connection element 2502 disposed on the second end 22 of the substrate 2, fixed on the lower face 23 of the substrate 2, where this second connection element 2502 is a soldered socket on this lower face. 23 and comprising:

a second anodic conductive part;

a second cathodic conducting portion; and

an insulator separating the second anodic conducting portion and the second cathodic conducting portion.

The two sockets 2501, 2502 are complementary so that they can fit into one another by male / female cooperation.

The end-to-end coupling of two LED filaments 1, according to this fourth embodiment, is as follows: the plug 2501 fits (or engages) inside the socket 2502.

Although reliable and removable, this coupling with a 2501 plug and a 2502 socket has a disadvantage in terms of the cost of the components 2501, 2502, compared to the first, second and third embodiments based on profiles.

Claims

1. LED filament (1) comprising:

- a substrate (2) elongate along a longitudinal axis (29), having a lower face (23) and an upper face (24) opposite, and having an opposite end (21) and second end (22);

a plurality of electroluminescent diodes (3) distributed in at least one row on the upper face (24) of the substrate (2);

an envelope (4) of transparent material containing fluorescent particles and covering the light-emitting diodes (3); and

at least one anode connector (61; 512; 161; 1512; 261) and at least one cathode connector (62; 522; 162; 1522; 262) electrically connected to the light-emitting diodes (3);

said LED filament being characterized in that it comprises:

a first anode connector (61; 161; 261) and a first cathode connector (62; 162; 262) disposed on the first end (21) of the substrate (2) and fixed on the underside (23) of the substrate (2); );

a second anode connector (512; 1512) and a second cathode connector (522; 1522) disposed on the second end (22) of the substrate (2) and fixed on the underside (23) of the substrate (2);

and or

one of the first anode connector and the second anode connector is in the form of a male anode connector (61; 161; 261) protruding from the corresponding first end (21) or second end (22) of the substrate; (2) along the longitudinal axis (29), while the other of the first anode connector and the second anode connector is in the form of a female anode connector (512; 1512) not exceeding the first end (21) or the corresponding second end (22) of the substrate (2) along the longitudinal axis (29);

one of the first cathode connector and the second cathode connector is in the form of a male cathode connector (62; 162; 262) protruding from the corresponding first end (21) or second end (22) of the substrate; (2) along the longitudinal axis (29), while the other of the first cathode connector and the second cathode connector is in the form of a female cathodic connector (522; 1522) not exceeding the first end (21) or the corresponding second end (22) of the substrate (2) along the longitudinal axis (29);

so that the first anode connector (61; 161; 261) and the second anode connector (512; 1512) are electrically connected and complementarily male / female, and the first cathode connector (62; 162; 262) and the second connector cathode (522; 1522) are electrically connected and complementarily male / female.

2. LED filament (1) according to claim 1, wherein the female connectors (512, 522; 1512, 1522) are flush with the first end (21) or the corresponding second end (22) of the substrate (2). along the longitudinal axis (29).

3. LED filament (1) according to any one of claims 1 and 2, wherein in the array, the light-emitting diodes (3) are regularly distributed along the longitudinal axis (29) with a main longitudinal spacing ( ELP) between each light-emitting diode (3), and furthermore:

- considering a first longitudinal gap (EC1) between the first end (21) of the substrate (2) and a first light-emitting diode (3) which is the light-emitting diode (3) closest to said first end (21) along the longitudinal axis (29), said first longitudinal gap (EC1) is between 0.25 and 0.75 times the main longitudinal spacing (ELP) of the row; and

considering a second longitudinal gap (EC2) between the second end (22) of the substrate (2) and a last light-emitting diode (3) which is the light-emitting diode (3) closest to said second end (22) along the longitudinal axis (29), said second longitudinal gap (EC2) is between 0.25 and 0.75 times the main longitudinal spacing (ELP) of the row.

The LED filament (1) according to claim 3, wherein the first longitudinal gap (EC1) is between 0.4 and 0.6 times the main longitudinal spacing (ELP) of the row, and the second longitudinal gap ( EC2) is between 0.4 and 0.6 times the main longitudinal spacing (ELP) of the row.

5. LED filament (1) according to any one of claims 1 to 4, comprising:

a first connection element (501) disposed on the first end (21) of the substrate (2), fixed on the lower face (23) of the substrate (2) and not extending beyond the first end (21) of the substrate ( 2) along the longitudinal axis (29), wherein said first connecting member (501) comprises a first anode conductive portion (51) and a first cathode conductor portion (52) separated by an insulator (54);

a second connection element (502) disposed on the second end (22) of the substrate (2), fixed on the lower face (23) of the substrate (2) and not extending beyond the second end (22) of the substrate ( 2) along the longitudinal axis (29), wherein said second connecting member (502) comprises a second anode conductive portion (51) and a second cathode conductor portion (52) separated by an insulator (54);

and or :

the male anode connector comprises a conductive anode pad (61) mounted in a hole (51 1) formed in one of the first anodic conducting portion (51) and the second anodic conducting portion (51), and the anode connector female comprises a hole (512) formed in the other of the first anodic conducting portion (51) and the second anodic conducting portion (51); and

the male cathodic connector comprises a cathode conductor pad (62) mounted in a hole (521) formed in one of the first cathodic conducting portion (52) and the second cathodic conducting portion (52), and the female cathodic connector comprises a hole (522) formed in the other of the first cathode conductor portion (52) and the second cathode conductor portion (52).

The LED filament (1) according to claim 5, wherein the holes (51 1,

521) in the first anode conductor portion (51) and the first cathode conductor portion (52) of the first connection member (501) have a first transverse gap (ET1) in a direction orthogonal to the longitudinal axis (29), the holes (512, 522) formed in the second anodic conducting portion (51) and the second cathodic conducting portion (52) of the second connecting member (502) have a second transverse gap (ET2) in a direction orthogonal to the longitudinal axis (29), and the first transverse gap (ET1) is different from the second transverse gap (ET2).

7. LED filament (1) according to claim 6, wherein the conductive anodic pad (61) and the conductive cathode pad (62) each have two opposite frustoconical ends.

The LED filament (1) according to any one of claims 5 to 7, wherein the holes (51 1, 512, 521, 522) are piercing holes.

The LED filament (1) according to any one of claims 1 to 4, comprising:

a first connection element (1501) disposed on the first end (21) of the substrate (2), fixed on the lower face (23) of the substrate (2), where the said first connection element (1501) comprises a first part anode conductor (151) and a first cathode conductor portion (152) separated by an insulator (154);

a second connection element (1502) disposed on the second end (22) of the substrate (2), fixed on the lower face (23) of the substrate (2), where the said second connection element (1502) comprises a second part anode conductor (151 ') and a second cathode conductor portion (152') separated by an insulator (154 ');

and or :

the first anode connector (161) is a male connector formed at one end of the first anodic conducting portion (151) projecting longitudinally from the first end (21) of the substrate (2) along the longitudinal axis (29); ), and the first cathode connector (162) is a male connector formed of an end of the first cathode conductor portion (152) projecting longitudinally from the first end (21) of the substrate (2) along the longitudinal axis (29); and

the second anode connector (1512) is a female connector formed by a notch formed in one end of the second anodic conducting portion (151 ') which does not protrude from the second end (22) of the substrate (2) along the longitudinal axis (29), and the second cathode connector (1522) is a female connector formed of a notch formed in one end of the second cathodic conducting portion (152 ') which does not protrude from the second end (22) of the substrate (2) along the longitudinal axis (29).

10. LED filament (1) according to any one of claims 5 to 9, comprising a connecting device (5) fixed on the underside (23) of the substrate (2), extending over the entire length (LO) of the substrate (2) from its first end (21) to its second end (22), said connecting device (5) comprising an anodic conducting portion (51) and a cathodic conducting portion (52) separated by an insulator ( 54), and the first connection element (501; 1501) constitutes a first end portion of the connection device (5) and the second connection element (502; 1502) forms a second end portion of the connection device (5).

1 1. The LED filament (1) of claim 10, wherein the anode conductive portion (51) and the cathode conductive portion (52) are conductive profiles of constant cross-section.

The LED filament (1) according to any of the preceding claims, wherein the first anode connector (61; 161; 261), the first cathode connector (62; 162; 262), the second anode connector (512; 1512). and the second cathode connector (522; 1522) are electrically connected to the light-emitting diodes (3) by vias passing through the substrate (2).

An LED filament (1) according to any one of the preceding claims, comprising an anodic lower track and a cathodic lower track fixed on the underside (23) of the substrate (2) and electrically connected to the light emitting diodes (3), and wherein the first anode connector (61; 161; 261) and the second anode connector (512; 1512) are attached to the bottom face (23) of the substrate (2) in contact with the anode lower track, and the first connector cathode (62; 162; 262) and the second cathode connector (522; 1522) are attached to the lower face (23) of the substrate (2) in contact with the lower cathode track.

A lighting line comprising at least two LED filaments (1) according to any one of the preceding claims, wherein said LED filaments (1) are arranged in alignment along their respective longitudinal axes (29) and are connected end to end. said LED filaments (1) comprising at least one upstream LED filament (1) and a downstream LED filament (1) interconnected with the first anode connector (61; 161; 261) and the first cathode connector (62; 162; 262) upstream LED filament (1) connected by male / female cooperation respectively to the second anode connector (512; 1512) and to the second cathode connector (522; 1522) of the adjacent downstream LED filament (1) for parallel connection of the upstream LED filament (1) and the adjacent downstream LED filament (1), and wherein the first end (21) of the substrate (2) of the upstream LED filament (1) is spaced from the second end (22) of the filament LED substrate (2). downstream (1) along their long axis tudinal with a longitudinal clearance (JL) of less than 2 millimeters.

15. Lighting line according to claim 14, wherein the longitudinal clearance (JL) is less than 1 millimeter, and in particular less than 0.5 millimeter.

16. Lighting line according to any one of claims 14 and 15, wherein the first end (21) of the substrate (2) of the upstream LED filament (1) is in contact with the second end (22) of the substrate ( 2) downstream LED filament (1).