WO2015069104A1

WO2015069104A1 - Profile for a led tube, led tube comprising said profile and method for assembling a led tube

Info

Publication number: WO2015069104A1
Application number: PCT/NL2014/050764
Authority: WO
Inventors: Paul Steffens; Jürgen Eduard HONOLD; Henk Emiel Cornelia CRONE; Tom HILGERINK
Original assignee: Silicon Hill B.V.
Priority date: 2013-11-11
Filing date: 2014-11-04
Publication date: 2015-05-14
Also published as: NL2011782C2

Abstract

The invention relates to a profile (10) for a LED tube (2), LED tube comprising said profile and method for assembling a LED tube (2). The profile (10) comprises an elongated base section having a substantially U-shaped cross section and a supporting section (24) extending from the base section for supporting a printed circuit board, PCB (12), wherein each of the arms of the base section is provided with a protrusion (27) for retaining the PCB between the supporting section and the protrusions, wherein the supporting section is formed by a resilient member.

Description

Profile for a LED tube, LED tube comprising said profile and method for assembling a LED tube

The invention relates to a profile for a LED tube. A LED tube is a tubular lighting, wherein the light source is formed by light emitting diodes, LEDs. LED tubes are often used as one to one replacement of fluorescent tubes, as LEDs provide many advantages in terms of energy efficiency and product life time. LED tubes comprise a profile for mounting the printed circuit board (PCB) with the LEDs in the tube. In most cases, the LED tube profile serves as a heat conductor to transfer the heat generated by the LEDs to the outside of the LED tube, i.e. to the surroundings.

A profile for a LED tube according to the preamble of claim 1 is known in the art. A problem of conventional profiles for LED tubes is that a gap is present between the supporting section and the PCB in order to take into account deviations in the dimensions of the PCB or the profile. This gap deteriorates the heat transfer from the PCB to the profile. Therefore, a heat conducting paste is usually applied between the PCB and the profile. However, this solution is not optimal in terms of heat transfer. Furthermore, applying the heat conducting paste increases the number of process steps for assembling the LED tube.

An object of the invention is to overcome or at least reduce the above disadvantages and to provide a profile for a LED tube allowing an improved heat transfer to the profile from a PCB mounted to the profile.

This goal is achieved with the profile for a LED tube according to the invention, the profile comprising

- an elongated base section having a substantially U-shaped cross section; and

- a supporting section extending from the base section for supporting a printed circuit board, PCB,

wherein each of the arms of the base section is provided with a protrusion for retaining the PCB between the supporting section and the protrusions, characterized in that the supporting section is formed by a resilient member.

The base section has a substantially U-shaped cross section, i.e. the base section comprises two interconnected opposing arms. It is noted that the cross section of the profile as a whole may not be U-shaped, for example the profile may have an H-shaped cross section, while still including a base section that has a substantially U-shaped cross section.

By forming the supporting section as a resilient member, when a PCB has been inserted in the profile the supporting section presses against the PCB, thereby improving the thermal contact between the PCB and the profile. The PCB is inserted into the profile against the spring force of the resilient member. After the PCB has been inserted between the supporting section and the protrusions, the resilient member continues to press against the PCB. The improved mechanical contact between the PCB and the profile leads to an improved heat transfer between these parts. Therefore, heat produced by the LEDs on the PCB is effectively transferred to the profile. As build up of heat is avoided, the life time of a LED tube comprising the profile according to the invention is increased.

A heat conducting paste may no longer be required. Therefore, the number of steps to assemble a LED tube is reduced. However, it is noted that a heat conducting paste and/or heat conducting tape may still be applied if desired.

Moreover, if a heat conducting paste is applied, the layer of conducting paste will be less thick due to a higher and equally distributed clamping force of the PCB against the supporting section. Therefore, heat transfer from the PCB to the profile is improved. Therefore, the profile serves as an effective heat sink.

An additional advantage of embodiments of the profile according to the invention is that it enables a new way of assembling a LED tube. In conventional LED tubes, the front of the PCB is inserted from a short side of the profile and between the supporting section and the retaining protrusions. The PCB is then slid along the profile until it is completely positioned within the profile. Due to the typical length of LED tubes, this way of assembling is cumbersome.

Furthermore, the sliding movement may damage the PCB. The profile according to the invention overcomes this disadvantages by enabling the PCB to be mounted in the profile from the top. One end of the PCB is inserted between the protrusion of a first arm of the base section and the supporting section, after which the other end of the PCB is pressed down, thereby snapping the PCB into place. The snapping or clicking operation is possible because the resilient member allows some movement of the arms of the U-shaped base section with respect to each other. This way of assembling the LED tube is faster and leads to less damage to the PCB.

For example, the profile is made of or comprises a metal or metal alloy, such as aluminium, copper or steel. In another example, the profile is made of or comprises thermal conductive plastic.

For example, the profile is produced by extrusion.

Preferably, the protrusions may extend over the entire length of the profile. For example, the protrusions are integrally formed with the profile by an extrusion process. Alternatively, the protrusions may extend over only a part of the length of the profile in the longitudinal direction of the profile.

The profile is preferably made of a material having a good thermal conductivity, e.g. a thermal conductivity higher than 50 W m ¹ K \ 100 W m ¹ K \ higher than 120 W m ¹ K \ higher than 150 W m ¹ K ¹ or higher than 200 W m ¹ K^"1. The supporting section may for example be provided with resilience by choosing an appropriate shape of the supporting section. For example, a part of the supporting section comprises a zigzag or undulating shape. In another example the supporting section comprises a zone with a reduced thickness to provide resilience. In a preferred embodiment the supporting section extends from a first arm of the base section towards a second arm of the base section.

The PCB may for example be inserted in the profile as follows. One end of the PCB is first inserted between the protrusion of the first arm of the base section and the supporting section. Subsequently, the other end of the PCB is pressed down against the second arm of the base section. Due to the force acting upon the second arm, the U-shaped profile will slightly open, i.e. the first arm and second arm move apart. The PCB will move past the protrusion of the second arm, thereby snapping the PCB into place.

In a further preferred embodiment according to the invention the resilient member is a tab having a free end, thus defining a gap between the second arm of the base section and the free end of the tab.

The tab provides resilience to the supporting section, while still allowing production of the profile in one piece and by means of extrusion.

In a further preferred embodiment according to the invention, the second arm of the base part comprises an abutment member arranged to limit the movement of the tab.

When assembling a LED tube based on the profile of the invention, the PCB is pressed down on the supporting section. As the supporting section exhibits resilience, it will also move in a downward direction, i.e. towards the base section. To avoid bending the tab too far and thereby deforming the tab, the abutment member limits the movement of the tab.

In an embodiment according to the invention, the base section further comprises an inner partition wall defining a tubular chamber extending in longitudinal direction of the base section.

The tubular chamber increases the torsional stiffness of the profile, requiring only a minor increase in mass. Torsion of the profile may result in detachment of the PCB from the profile and/or may result in damage of the PCB. Therefore, the increased torsional stiffness due to the tubular chamber prevents damage and/or detachment of the PCB.

Preferably, the tubular chamber is defined in a lower part of the profile. In particular, the tubular chamber may be defined below the supporting section.

In a further preferred embodiment, the resilient member extends from the inner partition wall.

In a preferred embodiment according to the invention the resilient member is moveable between a retaining position wherein the PCB is placed between the resilient member and the protrusions and a resting position wherein the resilient member extends at an angle a with respect to the plane defined by the PCB in the retaining position.

In other words, when placing the PCB the resilient member is displaced from its resting position, thus providing a spring force against the PCB when the PCB is locked in the retaining position, wherein the PCB is positioned between the resilient member and the protrusions of the base section of the profile. The supporting section of the profile is thus pressed tightly against the PCB, resulting in a firm contact between the PCB and the profile. Therefore, the heat transfer is improved and thus the lifetime of the LEDs is increased.

In particular, the resilient member may be a tab extending from the first arm as described above or a resilient member extending from a partition wall as described above.

In an embodiment according to the invention, the protrusion of the second arm of the base section is a resilient protrusion. This further improves the ease of assembly of the LED tube, as the PCB can be moved past the protrusion of the second arm more easily, even if the arms of the U- shaped base section only show a limited ability to move with respect to each other.

Additionally or alternatively, the protrusion of the second arm is formed on a resilient end zone of the second arm of the base section. In this embodiment, the outer end region of the second arm can be bent in an outward direction with respect to the profile. When the PCB is inserted by inserting one end between the supporting section and the retaining protrusion of the first arm and subsequently pushing the other end downwards past the protrusion of the second arm, the end zone of the second arm moves outwardly, i.e. away from the first arm. This allows for a quick and easy assembly of a LED tube. Furthermore, when the PCB is moved past the protrusion of the second arm, the end zone of the second arm will exert an inwardly directed force on the PCB, i.e. a clamping force, leading to a rigid fixation of the PCB in the profile.

In an exemplary embodiment one or both of the retaining protrusions may be movable between a first position wherein said protrusion does not obstruct the path of the PCB when placing the PCB on the supporting section, and a second position wherein said protrusion extends over the supporting section such that the PCB is positioned between the supporting section and said protrusion when the PCB has been placed on the supporting section. For example, the first position may be a substantially upright position, i.e. substantially perpendicular to the plane defined by the supporting section. The second position differs from a substantially upright position, e.g. the second position may be a position wherein said protrusion is substantially parallel to the supporting section. For example, the one or both protrusions can be moved back and forth between the first and second position. The PCB can be placed on the supporting section easily when one or both protrusions are in the first position as they do not extend over the supporting section. When the PCB has been placed, the one or both protrusions can be moved to the second position, e.g. by a snapping or bending movement, thereby retaining the PCB between the supporting sections and the protrusions. Preferably, at least the protrusion of the second arm is movable between the first position and second position as described above. The protrusion may be movable and/or bendable as a whole, or comprise one or more movable and/or bendable parts. Furthermore, the protrusion may be moved and/or bend over its entire length in the longitudinal direction of the profile, or alternatively only certain sections of the protrusion may be moved and/or bend. In an embodiment the protrusion of at least one of the arms of the base section has an inward facing surface at least a part of which is provided at an angle of at least 40 degrees with respect to the horizontal plane, preferably at least 50 degrees, more preferably at least 60 degrees, or for example at least 70 degrees. The angle is preferably less than 90 degrees.

By providing the protrusion of the at least one arm with an inclined surface, the PCB can be pressed into the profile using relatively less force.

In embodiments wherein the supporting section extends from a first arm of the base section towards a second arm of the base section, preferably the protrusion of at least the second arm has an inward facing surface as described above.

The inward facing surface may be a straight surface or a curved surface. In case of a curved surface, a part of the surface is provided at an angle of at least 40 degrees. In case of a straight surface, the whole surface may be provided at an angle of at least 40 degrees.

In a preferred embodiment according to the invention, the supporting section is provided with a groove near one of the arms of the base part for inserting a side of the PCB.

The groove provides room to tilt the PCB after one end is inserted in the profile.

In embodiments wherein the supporting section extends from a first arm of the base section toward a second arm of the base section, preferably the groove is provided near the first arm.

The base section may be provided with a recess and/or protrusion for stable positioning of the profile for assembly purposes.

In a first example, the base section is provided with a longitudinal recess having a substantially flat surface for stably positioning the profile on an assembly bench. Preferably, the recess is provided in a bottom portion of the base section, such as substantially opposite to the supporting section of the profile. The flat surface of the recess enables stable positioning of the profile during assembly.

In a second example, the base section is provided with protrusions on its outer surface, the protrusions having for example a substantially flat lower surface, preferably substantially horizontal. The profile can be stably positioned by positioning the flat lower surfaces of the protrusions on a suitable supporting structure.

Alternatively, the protrusion or recess may be provided with a different shape than a flat surface, the shape matching a shape of an assembly tool, for stably positioning.

In particular, the protrusion and/or recess prevents the profile from rotating around its centre axis when positioned on an assembly bench, e.g. when the PCB is pressed in.

The invention further relates to a LED tube comprising the profile as described above. The same advantages and effects as described above for the profile apply to the LED tube according to the invention. Preferably, the LED tube further comprises:

- a PCB positioned between the supporting section and the protrusion of the arms of the base section; and

- a cover for covering the PCB,

wherein the profile comprises a first attachment means and the cover comprises a second attachment means engaging with the first attachment means for attaching the cover to the profile.

As mentioned above the profile enables an improved attachment of the PCB to the profile as well as a faster and easier assembly. The cover covers the PCB with the LEDs. The cover is transparent or translucent, i.e. light passes through the cover. For example, the cover is made of a plastic, such as polycarbonate (PC), poly(methyl methacrylate) (PMMA) or polystyrene.

The first attachment means and second attachment means enable mechanically connecting the profile and the cover. Due to this mechanical connection, thermal expansion of the components of the LED tube can be absorbed. This is especially relevant in view of the large amount of heat generated by LEDs and the fact that the cover and the profile are usually made of different materials having a different thermal expansion coefficient. It is noted that this advantage also relates to the attachment of the PCB to the profile, which is also a mechanical connection.

Preferably, the first attachment means and second attachment means are arranged to form a snap connection, which enables an easy assembly of the LED tube.

In a preferred embodiment of the LED tube according to the invention, the support section is less stiff than the PCB. This has the advantage that the resilient supporting section will not deform the PCB.

In a preferred embodiment according to the invention the LED tube further comprises a phosphor element and the cover comprises a protruding member for clamping the phosphor element between said protruding member and at least one of the PCB and the supporting section.

A phosphor is a luminescent material, such as a phosphorescent or fluorescent material.

Phosphors are used in LED lighting to adjust the light spectrum with respect to the spectrum of the light emitted by the LEDs. The light emitted by the LEDs excites the phosphor, which re -emits light with a different wavelength (often a longer wavelength, i.e. more towards the red part of the visible spectrum).

The phosphor element may be provided from any suitable material, such as glass provided with a phosphor layer. By providing the protruding member to the cover, the phosphor element can be mechanically attached to the profile/PCB.

The mechanical connection of the phosphor element to the profile and/or the PCB has the advantage that thermal expansion of the components is taken into account, in contrast to other forms of connecting such as gluing. The wavelength shifting process of phosphors generates heat. Therefore, a phosphor is preferably placed remotely to the LEDs. This is called a remote phosphor configuration.

Preferably, the phosphor element according to the invention is a remote phosphor element. For example, the phosphor element is an elongated element having a substantially U-shaped cross section, wherein the arms of the U-shape are positioned on the PCB or the supporting section.

In a further embodiment the phosphor element comprises at least one flange for clamping the flange between the protruding member of the cover and at least one of the PCB and the supporting section. For example, the phosphor element is an elongated element having a U-shaped cross section wherein the flanges are attached to the ends of the arms of the U-shape.

In a preferred embodiment according to the invention the protrusions for retaining the PCB are integrally formed with the first attachment means of the profile. In other words, the profile comprises a section which functions both as a protrusion for retaining the PCB as first attachment means for attaching the cover. For example, a protrusion for retaining the PCB and a first attachment means are formed by a single element having a substantially T-shaped cross section.

The invention further relates to a method for assembling a LED tube, wherein the method comprises:

- providing a profile as described above; and

- positioning a printed circuit board, PCB, between the supporting section and the protrusions.

The same advantages and effects as described above for the profile and the LED tube apply to the method of the invention.

Preferably, the method comprises connecting a cover to the profile to cover the PCB. In a preferred embodiment the profile has a supporting section extending from a first arm of the base section towards a second arm of the base section, and the step of positioning the PCB comprises:

- inserting one end of the PCB between the supporting section and the protrusion of the first arm of the base section; and

- tilting the PCB while keeping said one end between the supporting section and the protrusion of the first arm of the base section thereby pressing the other end of the PCB past the protrusion of the second arm and thus mechanically locking the PCB between the supporting section and the protrusions of the base section.

Further advantages, features and details of the invention will be elucidated on the basis of exemplary embodiments thereof, wherein reference is made to the accompanying figures.

Figure 1 shows a first embodiment of a LED tube according to the invention;

Figure 2 shows a cross section of the first embodiment according to line II-II in figure 1 ; Figure 3 shows an exploded view of the components of the first embodiment of the LED tube;

Figures 4A-4C show in a front view cross section the assembly of the LED tube of the first embodiment;

Figures 5A-5B show a front view of a cross section of a first embodiment of a profile for a

LED tube according to the invention;

Figures 6A-6C show a front view of a cross section of a second embodiment of a profile for a LED tube according to the invention;

Figures 7A-7C show a variant according to the invention of the embodiment of figures 4A- 4C;

Figures 8A-8E show cross sections of profiles comprising a tubular chamber according to further embodiments of the invention;

Figures 9A-9D show cross sections of alternative profiles according to further

embodiments of the invention;

Figure 10 shows a cross section of a profile according to a currently preferred

embodiment; and

Figure 11A-B illustrate profiles according to an alternative embodiment, having differently shaped cross sections.

LED tube 2 comprises end caps 4, 6 and body 8 (figure 1). End caps 4, 6 are used for placing LED tube 2 in a fixture, wherein end cap 4 and/or end cap 6 is provided with electrical contacts to provide the LED tube 2 with electrical power.

Body 8 (figure 2) comprises a profile 10 which in this example is an extrusion profile of aluminium. Body 8 further comprises a printed circuit board (PCB) 12 on which the LEDs 18 of the tube 2 are provided. Optionally a remote phosphor element (14) is provided. Body 8 further comprises a cover 16. Cover 16 is transparent or translucent, i.e. it allows light to pass through. In the example shown cover 16 is made of polycarbonate (PC). However, the cover may also be made from other materials.

The profile 10 of tube 2 has a substantially U-shaped cross section, defining a first arm 22 and a second arm 20 (figure 4A). The profile 10 further comprises a section 24 for supporting the PCB, wherein the supporting section 24 extends from first arm 22 towards second arm 20. The supporting section 24 forms a resilient tab with a free end. The free end of tab 24 is provided at a distance of second arm 20, such that a gap 25 is formed between second arm 20 and the tab 24. Alternatively, the tab may be connected to the second arm 20 via a flexible part, e.g. a part having a zigzag shape or undulating shape, thus providing resilience to the tab 24.

The arms 20, 22 of the U-shape base of the profile 10 comprise protruding ribs 26, 28 for retaining PCB 12 between tab 24 and these ribs 26, 28. The second arm 20 of the base of the profile 10 is provided with a further protrusion 27 which serves as a abutment member which in this exemplary embodiment serves as an additional supporting surface such that PCB 12 is retained between ribs 26, 28 and supporting surfaces 24, 27. The protrusion 27 takes the form of a rib in this exemplary embodiment.

Supporting section 24 of the profile 10 comprises a groove 30, which is provided near the zone where section 24 is connected to the first arm 22. Groove 30 enables insertion of PCB 12 under an angle with respect to supporting section 24, after which the opposing end of the PCB can be pressed down to the position between ribs 26 and rib 27.

Profile 10 preferably comprises a mounting element 32 which has an opening for receiving a screw to mount the end caps 4, 6 to the body 8 of the tube 2. Profile 10 further comprises a recess 34 on its lower end which provides a flat surface, instead of continuing the substantially semicircular shape of the profile. The recess 34 defines two side walls bordering the flat surface. When the flat surface is positioned on an assembly tool, the side walls prevent the profile 10 from rotating around its centre axis, for example when the PCB is pressed in.

Cover 16 is provided with ribs 36, 38 (figure 4B). Ribs 36, 38 can engage with ribs 40, 42 of the profile 10. Cover 16 can be pressed down on profile 10 to form a mechanical connection by means of the ribs 36, 38 and ribs 40, 42.

In the case a phosphor element is provided, such as remote phosphor element 14, cover 16 preferably comprises protruding ribs 44, 46 to clamp the phosphor element against the PCB or supporting section 24. In the exemplary embodiment the remote phosphor element 14 comprises flanges 48, 50 which engage with the ribs 44, 46 of cover 16.

Tab 24 may be provided at an angle a with respect to the horizontal plane, as shown in figure 5A. In other words, in its resting position the free end of tab 24 is positioned further away from the base section than in the situation wherein the PCB 12 is placed on top of tab 24 (figure 5B). Therefore, when the PCB 12 is placed in the profile 10, the tab 24 exerts a force B from below to the PCB 12. The PCB 12 is retained by ribs 26, 28, which will exert a reaction force A on the PCB 12. Therefore, a tight contact between tab 24 and PCB 12 is ensured, improving heat transfer and improving the mechanical stability of the assembled tube.

In another exemplary embodiment (figures 6A-6C), the tab 24 has a thickness such that it is more flexible than the PCB 12. Depending on the stiffness of the material used for the profile, the tab may vary in thickness to adjust the force of the resilient member exerted on the PCB for giving enough pressure for good thermal contact, while not exerting too much force on the PCB to avoid bending of the PCB or damage the printed circuit by too much mechanical stress in the solder points of the SMD parts. In other words, the thickness of the tab is a design parameter which may be chosen dependent on e.g. the material of the profile, the dimensions of the profile and the tab and the desired retaining force on the PCB. In the embodiment shown the abutment member 27 serves to limit the movement of tab 24 in the downward direction. The retaining rib 26 of profile 10 is resilient to accommodate an easy positioning of the PCB 12 in the profile 10.

The assembly of a LED tube according to the method of the invention will now be explained with reference to the figures 4A-4C. Firstly, profile 10 is extruded from aluminium. Profile 10 is then preferably cut to size. The profile is placed on an assembly bench, wherein elongated recess 34 is placed over a matching part of the assembly bench. One side of the PCB with the LEDs is inserted in groove 30. The PCB is tilted such that its other end is moved past retaining rib 26, thereby mechanically locking PCB 12 in profile 10. Remote phosphor element 14 may be placed subsequently on PCB 12. Alternatively, PCB 12 has been provided with a remote phosphor element 14 before inserting it in profile 10. In another embodiment, no phosphor element is placed on the PCB. After fitting the PCB in profile 10 the cover 16 is attached to profile 10 by engaging ribs 36, 38 with ribs 40, 42 of the profile. In case a remote phosphor element 14 is provided, the ribs 44, 46 of cover 16 will engage with the flanges 48, 50 of the remote phosphor element 14. This completes the body of LED tube 2. Subsequently the end caps 4, 6 can be attached to body 8 using the attachment means 32.

Protrusion 26' (figure 7A-7C) is provided under an angle, e.g. under an acute angle greater than zero degrees with respect to the plane defined by supporting section 24. In the case of figures 7A-7C the protrusion is pointing slightly upwards. Preferably, protrusion 26' is resilient, such that it can be pressed against the PCB by cover 16, as shown in figure 7C.

Preferably, embodiments of the profile are provided with an inner tubular chamber (figures 8A-E). In a first example (figure 8A), partition wall 52 connects the first arm 22 to the second arm 20. Wall 52 defines a chamber 54, which preferably extends over the entire length of the profile. Optionally, a mounting element 32 is provided in chamber 54.

In the first example (figure 8 A) wall 52 has a first inclined portion, an adjacent horizontal portion and an adjacent second inclined portion. The angles between the adjacent portions are greater than 90 degrees. In a second example (figure 8B), wall 52 has a first vertical portion, an adjacent horizontal portion and an adjacent second vertical portion. The angles between the adjacent portion are substantially 90 degrees.

The second example also shows that optionally a mounting element 32 may be provided with a supporting rib 56.

The first example (figure 8A) shows a profile having a substantially flat lower surface. The further examples (figure 8B-E) show that the lower portion of the profile may have a substantially semi circular cross section. In a third example (figure 8C), the mounting element 32 is provided on a supporting rib 56 and connected to the partition wall 52 via wall 58. Effectively, rib 56 and wall 58 divide the chamber 54 into two compartments.

In a fourth example (figure 8D), a partition wall 60 defines the tubular chamber 54. The partition wall 60 has a substantially U-shaped cross section. Optionally, a mounting element 32 may be integrally formed with the partition wall 60, as shown in the figure. In the fourth example (figure 8D) the arms of the U-shaped partition wall show an angle of less than 90 degrees. In a fifth example (figure 8E), the arms are provided at an angle of substantially 90 degrees.

The tubular chamber 54 of each of the examples of figures 8A-8E increases the torsion stiffness of the profile, while very little mass is added by including partition wall 52 or 60.

Figures 9A-D show alternative embodiments of the profile, wherein the supporting section 24 has been modified. In a first example (figure 9A), the profile comprises a partition wall 60 that defines a tubular chamber 54 in a lower portion of the profile. A resilient member 62 is formed as a leaf spring. In the example shown, the resilient member 62 is formed by a substantially V-shaped tab 62 extending from a first arm of the profile. A substantially flat upper surface of tab 62 serves as supporting surface for a PCB.

In a second example (figure 9B), a resilient member 64 extends from the partition wall 60. The resilient member 64 comprises an upper horizontal surface which is attached to the partition wall by a connection wall part 65.

In a third example (figure 9C), a resilient member 66 is formed as a tubular part 66 having a substantially flat upper surface for supporting a PCB. The walls of tubular part 66 are sufficiently thin to provide resilience, i.e. spring action. The resilient member 66 is supported by partition wall 60.

In a fourth example, the resilient member 68 is formed as a leaf spring. The resilient member 68 extends from the partition wall 60 of chamber 54 and is provided with a substantially flat upper surface for supporting a PCB.

In a currently preferred embodiment (figure 10), the profile comprises a partition wall 60 which has been integrally formed with mounting element 32. The supporting section 24 is formed as a tab 24 extending from the first arm 22 of the substantially U-shaped profile. Tab 24 is slanting upwards as it extends from arm 22 and then curves towards a substantially straight section for supporting the PCB. Similarly to the embodiment of figure 5, the straight supporting portion towards the free end of tab 24 is provided under a small acute angle a.

The protrusion of the second arm 20 has an inclined inner surface 70. The normal to inner surface 70 has a component in the upward direction. Likewise, the protrusion 28 of first arm 22 may optionally also be provided with an inclined inner surface 72. In the example shown, the incline of the inner surface 70, 72 is about 60 degrees with respect to the horizontal plane. By providing an inclined surface 70, 72 the PCB can be pushed past the protrusions more easily.

Each arm of the profile is provided with a recess 73, 75 for receiving a PCB. Each recess 73, 75 is delimited by protrusions 26, 28. The PCB may be mounted in the profile by placing a first end of the PCB in recess 75 of the first arm 22. Subsequently, the other end of the PCB is pressed downwards, against inclined surface 70 of protrusion 26 of second arm 20. To enable tilting the generally rectangular PCB within recesses 73, 75 a groove 74, 76 may be provided.

When inserting the PCB, the PCB presses the arms 20, 22 apart, such that the PCB can pass protrusion 26 and enter recess 73. The profile will then snap back, thereby locking the PCB in recesses 73, 75. While pressing the PCB in the profile, the slightly slanted supporting section 24 has been displaced against its spring force. Therefore, it will press against the PCB when the PCB has been snapped into the profile.

The outer surface of the profile may be provided with protrusions 78 which provide a flat lower supporting surface 80. The supporting surface 80 enables stable positioning of the profile on e.g. an assembly bench, preventing rotation of the tube around its centre axis, e.g. when the PCB is pressed in. The lower part of the profile preferably has a curvature, e.g. a substantially semicircular cross section. This increases the torsion stiffness of the profile.

One or more additional recesses 82 may be provided to enable attaching a cover to the profile.

The profile of figure 10 has a base section which has a substantially U-shaped cross section. For illustrative purposes, a U-shape has been indicated with dashed line 83.

The profile may have another general cross section. In an exemplary embodiment (figure 11 A) of a profile according the invention, the profile 84 as a whole has a substantially H-shaped cross section. Two opposing side walls 26, 28 are connected via web 86, thus forming a base section 88. Profile 84 further comprises feet 90, 92 which are extensions of the side walls 26, 28 beyond the web 86. Although the feet 90, 92 provide profile 84 with an overall H-shaped cross section, the base section 88 of profile 84 is substantially U-shaped, as indicated with dashed line 94. In another exemplary embodiment (figure 1 IB) of a profile according to the invention, the profile 96 comprises opposing side walls 26, 28 interconnected by web 98. The form of cross section of the base section of profile 96 deviates from a strict U-shape and resembles a W-shape. However, the W-shape is still covered by the term "substantially U-shaped", as indicated by dashed line 100. Another example of a substantially U-shaped cross section includes a V-shaped cross section. The present invention is by no means limited to the above described exemplary or preferred embodiments thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.

Claims

1. Profile for a LED tube, comprising

- an elongated base section having a substantially U-shaped cross section; and

- a supporting section extending from the base section for supporting a printed circuit board,

PCB,

wherein each of the arms of the base section is provided with a protrusion for retaining the PCB between the supporting section and the protrusions,

characterized in that the supporting section is formed by a resilient member.

2. Profile according to claim 1 , wherein the supporting section extends from a first arm of the base section towards a second arm of the base section.

3. Profile according to claim 2, wherein the resilient member is a tab having a free end, thus defining a gap between the second arm of the base section and the free end of the tab.

4. Profile according to claim 3, wherein the second arm of the base part comprises an abutment member arranged to limit the movement of the tab.

5. Profile according to any of the preceding claims, wherein the base section further comprises an inner partition wall defining a tubular chamber extending in longitudinal direction of the base section.

6. Profile according to claim 1, wherein the base section further comprises an inner partition wall defining a tubular chamber extending in longitudinal direction of the base section, wherein the resilient member extends from the inner partition wall.

7. Profile according to any of the preceding claims, wherein the resilient member is movable between a retaining position wherein the PCB is placed between the resilient member and the protrusions and a resting position wherein the resilient member extends at an angle (a) with respect to the plane defined by the PCB in the retaining position.

8. Profile according to any of the preceding claims, wherein the protrusion of at least one of the arms of the base section has an inward facing surface at least a part of which is provided at an angle of at least 40 degrees with respect to the horizontal plane, preferably at least 50 degrees, more preferably at least 60 degrees.

9. Profile according to any of the preceding claims, wherein the supporting section is provided with a groove near one of the arms of the base section for inserting a side of the PCB.

10. Profile according to any of the preceding claims, wherein the base section is provided with a recess and/or protrusion for stably positioning of the profile for assembly purposes.

11. LED tube comprising the profile according to any of the preceding claims.

12. LED tube according to claim 11, wherein the supporting section is less stiff than the PCB.

13. LED tube according to claim 11 or 12, wherein the LED tube further comprises:

- a PCB positioned between the supporting section and the protrusions of the arms of the base section; and

- a cover for covering the PCB,

14. LED tube according to claim 13, wherein the first attachment means and second attachment means are arranged to form a snap connection.

15. LED tube according to claims 13 or 14, wherein the LED tube further comprises a phosphor element, wherein the cover comprises a protruding member for clamping the phosphor element between said protruding member and at least one of the PCB and the supporting section.

16. LED tube according to claim 15, wherein the phosphor element comprises at least one flange for clamping the flange between the protruding member of the cover and at least one of the PCB and the supporting section.

17. LED tube according to any of the claims 13-16, wherein the protrusions for retaining the PCB are integrally formed with the first attachment means of the profile.

18. Method for assembling a LED tube, wherein the method comprises:

- providing a profile according to any of the claims 1-10; and

- positioning a printed circuit board, PCB, between the supporting section and the

protrusions.

19. Method according to claim 18 further comprising connecting a cover to the profile to cover the PCB.

20. Method according to claim 18 or 19, wherein the profile is a profile according to claim 2, wherein the step of positioning the PCB comprises:

- tilting the PCB while keeping said one end between the supporting section and the protrusion of the first arm of the base section, thereby pressing the other end of the PCB past the protrusion of the second arm and thus mechanically locking the PCB between the supporting section and the protrusions of the base section.