The present invention relates to a tubular LED lamp and a corresponding production method thereof. The present invention also relates to individual components of the tubular LED lamp, namely a plastic carrier for holding one or more LED modules inside a lighting tube of the tubular LED lamp, and an end seal for sealing an end of lighting tube of the tubular LED lamp.

Tubular or linear LED lamps are known in the state of the art. Many tubular LED lamps have a retrofit design, and are intended to replace known gas discharge lamps. To this end tubular LED lamps comprise lighting tubes, into which light engines or LED modules, which typically comprise an elongated printed circuit board, PCB, with a plurality of LEDs, are inserted.

For placing one or more LED modules into the lighting tube two approaches are mostly used in prior art. The first approach places LED modules into a lighting tube, wherein the LED modules comprises low power LEDs, and wherein no means for heat transfer or for a robust mechanical fixing of the LED modules to the lighting tube are provided. The second approach fixes LED modules onto a metal, e.g. aluminum, heat sink, which itself is glued to the lighting tube .

For example, US 2002/0047516 Al discloses a fluorescent tube constituted by a fluorescent tubular body made of transparent glass coated with a fluorescent layer and having an ultraviolet LED substrate inserted into the tubular body. The LED substrate is attached via support holes and supporting cords to Teflon plugs located on both ends of the lighting tube. US 2011/0038147 Al discloses an assembly structure for an LED lamp. A plurality of LEDs is mounted on a substrate. The substrate is fixed by fasteners to the tube he LED lamp.

Document WO 2011/064305 Al discloses a linear lamp having a tubular bulb of glass, wherein a plurality of LEDs is mounted onto a PCB, which is inserted into the bulb. The PCB may be made from a material like aluminum or ceramic to provide a heat sink. The PCB is molten into the glass during the production process. WO 2011/121145 Al discloses an LED tube including a body made of a highly heat conducting extruded material in the shape of a tube. The tube has a hole for receiving at least one LED mounted on a PCB. The PCB is attached to the tube via fixing means via boreholes.

The problem with the first state of the art approach is its reliability, since no adequate heat transfer and no stable mechanical fixing is provided. The approach can further support only a limited diameter of lighting tubes, and thus a limited light output. This is due to the fact that the smaller the tube diameter is designed, the better the heat conductivity inside the tube is, and naturally a certain amount of heat conductivity has to be provided. The problem with the second approach is that manufacturing these lamps is difficult, and that the interfaces of aluminum and glass are firstly difficult to construct, and secondly hardly form a thermal interface that matches the different heat extension coefficients of the materials.

The present invention has thus been made, in order to improve the state of the art. In particular one or more of the above-mentioned problems are to be overcome. In general the object of the invention is to provide an improved tubular LED lamp that can replace known gas discharge lamps both to the mechanical connections and the optical characteristics. In particular, the present invention desires to build a tubular LED lamp with improved optical and thermal characteristics and improved stability. A further object of the present invention is to provide a tubular LED lamp, which can be easily fabricated, and wherein tubular LED lamps can be produced easily with various lengths.

The above-mentioned problems are solved by the present invention according to the attached independent claims. The attached dependent claims further develop the inventive concept of the present invention by providing additional advantageous features.

The present invention relates to a plastic carrier for holding one or more LED modules inside a lighting tube, wherein the plastic carrier comprises at least one bendable part adapted to hold the plastic carrier inside the lighting tube by being biased and thus pressing against the inner wall of the lighting tube. The plastic carrier does not need to be glued or otherwise fixed by separate fixing means to the lighting tube. The plastic carrier is rather held by friction with the lighting tube. The plastic carrier is partly deformed when inserted into the lighting tube. Due to the elasticity of at least the bendable parts of the plastic carrier, an elastic force, similar to a spring force of a biased spring, will push at least the bendable parts of the plastic carrier against the inner wall of the lighting tube. The plastic carrier can thus be clamped inside the lighting tube.

The plastic carrier can be inserted and removed very easily into and from the lighting tube. The production and maintenance of the tubular LED lamp thus becomes simpler. The plastic carrier is further used to transmit heat produced by the LED modules to the wall of the lighting tube. No separate heat sink, e.g. a heat sink made from aluminum, is required. Since there is no glue connection or any other rich connection between the plastic carrier and the lighting tube, there is a wide range of compensation for different thermal characteristics between the material of the lighting tube and the material of the plastic carrier. The material of the lighting tube is preferably glass, and optionally plastic.

Preferably, the plastic carrier has a roughly semi- cylindrical shape with a first end face, a second end face, a planar top surface, and a semicircular bottom surface .

The semicircular bottom surface of the plastic carrier is preferably designed such that it matches at least partly the radius or curvature of the lighting tube, into which the plastic carrier is to be inserted. The semicircular bottom surface then has a large contacting surface with the lighting tube when inserted, which results in a better heat transfer. The plastic carrier can therefore act efficiently as a plastic heat sink.

The end faces of the plastic carrier can provide electrical contacts that are connected to the LED modules. Electrical contacts for the LED modules are preferably provided at both opposed ends of the plastic carrier.

Preferably, the bendable part comprises a plurality of bendable arms that extend on opposite sides of the planar top surface, extend roughly perpendicular to the planar top surface, and extend in tangential continuation of the semicircular bottom surface. The bendable arms can be biased, before fitting the plastic carrier into the lighting tube. Due to their elasticity, the bendable arms will then press against the inner wall of the lighting tube when inserted. The bendable arms are designed so as to roughly continue the curvature of the circular bottom surface, which is roughly perpendicular to the top surface, due to the semi- cylindrical shape of the plastic carrier.

A plurality of bendable arms can be provided on each side of the planar top surface, wherein a distance between the individual bendable arms is the same or varies. A plurality of bendable arms is able to provide high friction force to hold the plastic carrier stably inside the lighting tube. The bendable arms can be straight or curved. If they are curved, the radius should be larger than that of the lighting tube, into which the plastic carrier is inserted. Then, to adapt the curvature of the bendable arms to the radius of the inner wall of the lighting tube, the bendable arms necessarily need to be biased. The bendable arms provide further heat transfer from the plastic carrier to the lighting tube, and can even act as heat fins, which efficiently transfer heat to air or solid material surrounding the arms. Preferably, the bendable arms are designed such that their pressing against the inner wall of the lighting tube results in a force that presses the semicircular bottom surface against the inner wall of the lighting tube.

Since the semicircular bottom surface is pressed against the inner wall of the lighting tube, the interface to the lighting tube is increased and improved, and therefore a better heat transfer can take place. Further, the frictional force between the plastic carrier and the lighting tube is increased, so that the plastic carrier is held even more stably inside the lighting tube.

Preferably, the plastic carrier has a first end face, a second end face, a top surface and a bottom surface, wherein the bendable means are a plurality of curved bendable arms that extend from opposite sides of the bottom surface. In this alternative embodiment for the plastic carrier, the bendable arms extend away from the top surface of the plastic carrier, onto which the LED modules are mounted. The curvature of the bendable arms is chosen such that they can be biased to match the curvature of the lighting tube, into which the plastic carrier is to be inserted. Then inside the lighting tube the bendable arms will press against the inner wall of the lighting tube.

Since the bendable arms in this embodiment extend from the opposite surface from the surface where the LED modules are mounted, the LED modules will become arranged closer to the inner wall of the lighting tube when inserted with the plastic carrier. A volume or void between the LED modules and the inner wall of the lighting tube can thus be drastically reduced. Said void is preferably filled with a matrix material, as will be explained later. Due to the reduction of the volume of the void that is to be filled with matrix material, the production process can be made more cost efficient. Also the light produced by a tubular lamp with such a construction can be brighter.

Preferably, the number and position of the plurality of bendable arms is selected such that there is no resulting torsion of the plastic carrier when held by the bendable arms in a lighting tube.

For example, the same number of bendable arms can be provided on each side of the top surface. If further the elasticity of each bendable arm is identical, no torsion will result of the plastic carrier when inserted into the lighting tube. However, other configurations are possible and can be carefully selected. The forces that are exerted by each of the bendable arms that press against the inner wall of the lighting tube have to be balanced. In particular a balance between either side of the top surface and a balance along the length of the plastic carrier is desired. The result is an increased stability of the plastic carrier inside the lighting tube.

Preferably, the plastic carrier comprises a fitting portion on the top surface, which is adapted to receive and hold the one or more LED modules. The fitting portion can mechanically hold and fix one or more LED modules. For example a snap fitting can be provided. Additional protrusions can be provided, under which one or more LED modules can be clamped. With such constructions it is not necessary to glue the LED modules to the plastic carrier, whereby a simpler production method and better thermal characteristics are achieved.

Preferably, the plastic carrier has a thermal conductivity of 0.1 W/mK to 20W/mk.

The plastic carrier can thus act well as a heat sink and can replace heat sinks like e.g. aluminum profiles, which are used in the prior art.

Preferably, the plastic carrier is made from a highly reflective material or an at least partially transparent material . If the plastic carrier is made from a highly reflective material, it can form an optical cavity or, for example, a parabolic mirror for an ideal color and light distribution of the tubular LED lamp. With the plastic carrier being at least partially transparent, light distribution can occur in all directions.

Preferably, the plastic carrier comprises at least one color conversion material. By means of the color conversion material different colors of the light emitted by the tubular LED lamp can be selected. White light can, for example, be produced by using blue LEDs for the LED modules and using a color conversion material that adds an extras spectral wavelength (preferably yellow) to the blue LED light, so that the total emission is perceived as white light.

Preferably, the plastic carrier comprises a first snap connector extending from the first end face, and a second snap connector extending from the second end face, wherein the first snap connector and the second snap connector are shaped such that they are adapted to engage with a second snap connector and a first snap connector of another plastic carrier, respectively.

Due to the construction of the snap connectors, multiple plastic carriers can be connected in a longitudinal direction, in order to produce longer lamps. Typical lengths of individual plastic carriers, which can be connected to each other, are 30 to 40 cm. By connecting several subunits, i.e. several plastic carriers, the lengths of tubular LED lamps can be varied (of course lighting tubes of different length have to be chosen) . The snap connector further provides a simple mechanism, which requires no glue or similar fixation.

Preferably, the first snap connector and the second snap connector are designed such that they prevent a twisting of the plastic carrier in respect to another engaged plastic carrier.

The snap connector can be composed for example of several parts, which engage with several parts of another snap connector, respectively. The engagement should be releasable only by exerting a sufficient force on the plastic carriers along the length of a tubular LED lamp, but not by twisting the plastic carriers. Two plastic carriers that are connected to each other should not be able to twist at all in respect to each other around their respective longitudinal axis. Twisting of adjacent plastic carriers (subunits) would also twist the LED modules, and would result in deteriorated optical characteristics of the whole tubular LED lamp. The present invention further relates to a tubular lamp comprising at least one lighting tube, at least one plastic carrier, as described above, held by the bendable means inside the at least one lighting tube, and one or more LED modules mounted on the plastic carrier.

The tubular LED lamp can replace known discharge gas lamps and can be easily built with different lengths. The plastic carrier does not need to be glued or otherwise fixed in the lighting tube. Therefore the lamp can be assembled faster. The tubular LED lamp has good thermal characteristics, since the plastic carrier serves to transfer heat from the LED modules to the lighting tube, i.e. it acts as a heat sink.

Preferably, the lighting tube is made of glass or plastic.

Preferably, the tubular lamp comprises a plurality of plastic carriers that are connected to each other by respectively engaging a first snap connector of one plastic carrier with a second snap connector of another plastic carrier. The tubular lamp can thus be varied in length easily by inserting a desired number of plastic carriers connected to each other via the snap connectors into a lighting tube of desired length. The present invention further relates to an end seal for sealing a lighting tube and connecting to a plastic carrier inside the lighting tube, wherein the end seal comprises a cylindrical base body with a first end and a second end, and a snap connector provided at the first end for engaging with a snap connector provided at an end of the plastic carrier.

The end seals can easily be attached to the one or more plastic carriers inside the lighting tube via the snap connector. There is no need for gluing or screwing them to the lighting tube. When the plastic carrier is to be removed from the lighting tube for an exchange or maintenance of the LED modules, the snap connection can be quickly resolved.

Preferably, the base body and/or the snap connector are made of plastic. Preferably, the diameter of at least a part of the cylindrical base body is selected to match the inner diameter of the lighting tube that is to be sealed.

Preferably, the cylindrical base body comprises a portion of increased diameter at the second end.

The cylindrical base body of the end seal can be slid into the lighting tube, until the end of the lighting tube is sealed by the portion of increased diameter.

Preferably the portion of increased diameter is provided with a first through hole and at least one second through hole . The first through hole can be used to inject a sealing material through the portion of increased diameter into the lighting tube, where it will act as a seal and glue for the end seal. The air that is necessarily replaced by the sealing material is ejected through the second through hole .

Preferably the at least one second through hole has a smaller diameter than the first through hole.

Due to the smaller diameter of the second through hole, once all air is replaced by the injected sealing material, and once the sealing material starts to exit through the second through hole it will get stuck in the through hole due to its viscosity.

Preferably the cylindrical base body comprises a portion of decreased diameter in its mid section.

The portion of decreased diameter in the mid section of the base body acts as a sealing space with the inner wall of the lighting tube. The sealing space fills with sealing material when such is injected.

Preferably, the base body comprises an elongate groove extending along at least a part of the base body, wherein the elongate groove is aligned to continue the first through hole after the portion of increased diameter.

The elongated groove is provided so that the injected sealing material is distributed more evenly in the sealing space . Preferably, the base body is provided with an annular groove for receiving an O-ring.

If an O-ring is aligned in the groove of the sealing space, which is defined by the portion of decreased diameter in the mid section of the base body, the sealing space is sealed even more tightly to the inside of the lighting tube, where the plastic carrier and the LED modules are situated.

Preferably, the end seal comprises a conduit that extends from the first end to the second end through the whole base body. The conduit can be used to fill the inside of the lighting tube, i.e. the void between the plastic carrier and the LED modules, respectively, and the lighting tube with a matrix material, e.g. a phosphor containing material. The conduit is preferably a channel that runs straight from the first end to the second end of the base body. The diameter of the conduit should be large enough to allow an efficient injection of viscous matrix material.

Preferably, electrical connections for the LED modules extend through the base body.

The LED modules inside the lighting tube 3 of a tubular LED lamp can then be easily contacted from the outside. The present invention further relates to a tubular lamp comprising at least one lighting tube, at least one plastic carrier inside the at least one lighting tube, the plastic carrier being provided with a snap connector on each of its ends, one or more LED modules mounted on the plastic carrier, and two end seals as described above, wherein the snap connector of each end seal is removably engaged with the snap connectors of the plastic carrier. The tubular lamp can be assembled and disassembled in an easy manner without screwing.

Preferably, voids inside the lighting tube between the LED modules and the plastic carrier, respectively, and the inner wall of the lighting tube are filled with a matrix material .

In this way the lamp is efficiently sealed against dust and dirt entering the lighting tube. The life time can thus be prolonged. Further, the matrix material in the lighting tube can improve the optical characteristics of the LED lamp. The matrix material can change the emitted wavelength and can, for example, assist in production of white light.

Preferably, the matrix material comprises a silicone material . Preferably, the matrix material comprises one or more phosphors .

The present invention is directed to a production method of a tubular lamp, the method comprising the steps of mounting at least one or more LED modules on a plastic carrier, inserting the plastic carrier into a lighting tube, connecting an end seal to each end of the plastic carrier to seal the lighting tube, injecting a matrix material through a conduit through at least one of the end seals to fill voids between the one or more LED modules and the inner wall of the lighting tube.

By filling the voids between the LED modules and the lighting tube with a matrix material, the mechanical and optical properties of the tubular lamp can be altered or improved. The filling can even take place after assembly of the lamp. The matrix material may on the one hand side act as glue that fixes the plastic carrier and the LED modules together, and can on the other hand side act as an optical medium that tailors the optical characteristics.

Preferably, the insertion of the plastic carrier comprises deforming at least a part of the plastic carrier, so that it is biased and thus presses against the inner wall of the lighting tube.

By biasing the plastic carrier before or by inserting it into the lighting tube, the deformed part of the plastic carrier will exert a spring force, which arises due to its elasticity, onto the inner wall of the lighting tube. Therefore, the plastic carrier is held by frictional forces inside the lighting tube. The matrix material can further act as glue. No screws or similar fixing means are required.

Preferably, the matrix material contains one or more phosphors . With the matrix material containing one or more phosphors, the spectral characteristics of the lamp can be tailored. For example, white light can be achieved. Therefore, the LED modules might emit blue light, and the phosphor particles in the matrix material add when exited by the blue light a further wavelength (like yellow) to the light, so the perceived total light of the lamp lies in the white region of the light spectrum. Preferably, the method further comprises a step of coating, prior to injecting the matrix material, an inner wall of the lighting tube with a material comprising at least one phosphor.

The coating material can additionally influence the optical characteristics of the tubular lamp. For example, color conversion or light dispersion can be achieved. Preferably, the method further comprises a step of injecting, prior to injecting the matrix material, a filling material to selectively cover an inner wall of the lighting tube.

In this way two layers of two different materials can be provided to be located between the LED modules and the inner wall of the lighting tube. More flexibility when tailoring the optical characteristics of the tubular lamp is achieved.

Preferably, the method further comprises a step of injecting a sealing material through a first through hole of each of the end seals to respectively fill a sealing space between the end seals and the inner wall of the lighting tube.

The sealing material can be the same as the matrix

material. This solution is preferred if a fast, lower cost production method is desired. Both the sealing and the matrix material can comprise silicone material and/or two- component silicone material. The materials are preferably different from each other, if optimization of the

individual properties is desired, i.e. the sealing

properties of the sealing material on the one hand side, and the optical properties of the matrix material on the other hand side.

The sealing material can fill a sealing space and glue the end seals of the lamp to the inner walls of the lighting tube. The inside of the lighting tube, where the LED modules are situated, is then well protected against dirt and dust.

Preferably, the sealing material comprises silicone material. Silicone material is a cheap and well working sealing material.

Preferably, the method further comprises a step of positioning the lighting tube in an upright orientation for the steps of injecting the matrix material and/or the sealing material.

Preferably, the injected matrix material and the sealing material glue the plastic carrier and the end seals, respectively, to the lighting tube.

The mechanical stability of the tubular lamp can thus be improved. Also the temperature characteristics can be improved, since the heat can now be additionally transferred via the injected matrix material from the LED modules to the lighting tube. The matrix material can act as an additional heat sink with a large surface to the plastic carrier. The matrix material also protects the LED modules .

Preferably, in the injection step of the sealing material air is released though at least one second through hole of at least one of the end connectors. The release of air allows for an improved sealing without any air bubbles being enclosed in the sealing material. The stability is thus increased, and the probability of deterioration of the sealing material with time is reduced.

Preferably, the diameter of the second through hole is smaller than the diameter of the first through hole so that sealing material is prevented from exiting though the second through hole. The sealing material will automatically seal the second through hole.

Preferably, the method further comprises a step of dispensing a globe top onto the one or more LED modules after mounting the one or more LED modules on the plastic carrier .

A transparent globe top material leads to the advantage that the injected matrix material is slightly distanced from the light (and heat) producing surface of the LED dies on the LED modules. Thus, the requirements as to the temperature stability of the matrix material or the phosphors inside the matrix material can be lowered. Silicone can be used as a matrix material. The one or more phosphors additionally tailor the optical characteristics of the tubular lamp.

Preferably, the globe tops are formed by dispensing a transparent material that preferably contains one or more phosphors.

Preferably, in the mounting step the one or more LED modules are mechanically fixed to a fitting portion of the plastic carrier. The production method is simplified since the LED modules do not have to be glued or soldered. The present invention is further directed to a tubular lamp obtained by the production method described above.

The tubular lamp obtained has all the advantages described above .

In summary the present invention presents a plastic carrier, an end seal and a production method for a tubular lamp. The resulting tubular lamp has improved optical and mechanical characteristics, e.g. in terms of stability and desired light. The tubular lamp can be fabricated easier than commonly known tubular lamps.

In the following the present invention will be explained in more detailed with reference to the attached drawings.

Fig. 1 shows a first embodiment of a plastic carrier according to the present invention.

Fig. 2a and 2b show a first embodiment of a plastic carrier according to the present invention.

Fig. 3a and 3b show a first embodiment of a plastic carrier according to the present invention. Fig. 4 shows a connection of two snap connectors of a plastic carrier according to the present invention.

Fig. 5a and 5b show a second embodiment of a plastic carrier according to the present invention. Fig. 6a and 6b show a first embodiment of an end seal according to the present invention. Fig. 7 shows a second embodiment of an end seal according to the present invention.

Fig. 8b shows a tubular lamp designed and produced according to the present invention. Fig. 8a and 8c show an end seal according to the present invention in a lighting tube of a tubular lamp.

Fig.l shows a plastic carrier 1 according to the present invention. In particular, fig. 1 shows a plastic carrier 1 according to a first embodiment. The plastic carrier 1 is inserted into a lighting tube 3 for assembling a tubular lamp 20. The plastic carrier 1 is held by frictional and elastic forces inside the lighting tube 3. The plastic carrier 1 does not need to be glued or otherwise fixed (e.g. with separate fixing means like screws) to the lighting tube 3. Responsible therefore is that a part of the plastic carrier 1 is bendable, and can be biased before or during inserting the plastic carrier 1 into the lighting tube 3. The elasticity of the bendable parts 4 will then act like a biased spring, and exerts a pushing force against the inner wall of the lighting tube 3. The bendable parts 4 are shown in fig. 1 as being for example two biased arms 4a that are adapted to push against the inner wall of the plastic tube 3.

The plastic carrier 1 is provided with an LED module 2 that is mounted on its top surface. The LED module 2 comprises one or more LEDs, and produce light and heat when in operation. Thus, the plastic carrier 1 is configured to function as a heat sink, in order to transfer heat from the LED module 2 to the lighting tube 3. The plastic carrier 1 is therefore preferably made of a common polymer, like polyamide, poly-ethyl-terephtalate, polycarbonate, polypropylene, LCP, PPS, TPE, elastomers or the like. The plastic carrier 1 can also be made from highly filled polymers to achieve a better heat conductivity. The heat conductivity of the plastic carrier 1 is preferably in a range of 0.1 W/mK to 20W/mK, more preferably lW/mK to 20W/mK, most preferably lOW/mK to 20W/mK. The lighting tube 3 is preferably made of glass, but can optionally be made of a plastic material.

The plastic carrier 1 can be made from a highly reflective plastic material or can be provided with a reflective coating on its surfaces. Then the plastic carrier 1 can function as an optical cavity or as a parabolic mirror, in order to reflect, focus or redirect light that has been emitted by the LED modules 2. An optical cavity can be designed for ideal color and light distribution of the LED modules. Purposely directed emission of light can be achieved. Alternatively, the plastic carrier 1 can be at least partially transparent so that light that is distributed from the LED modules is not blocked by the plastic carrier 1, and can thus be emitted in all directions .

In the first embodiment the plastic carrier 1 is shaped to have a first end face 6a, a second end face 6b, which are arranged on opposite ends of the semi-cylindrical plastic carrier 1. The plastic carrier 1 further has a planar top surface 5a and a semicircular bottom surface 7a as shown in fig. 1. The curvature or radius of the semicircular bottom surface 7a preferably matches the curvature or radius of the inner wall of the lighting tube 3, into which the plastic carrier 1 is to be fitted for assembling a tubular lamp 20. One or more LED modules 2 are mounted onto the planar top surface 5a of the plastic carrier 1. Preferably, the top surface 5a has a fitting portion 9, e.g. a recess or a cavity, into which the LED modules 2 can be placed. Additionally, protruding and bendable elements can be provided, under which the LED modules 2 can be clamped. Preferably, the LED modules 2 can be held stably in the fitting portion 9 without the use of glue. The LED modules 2 can for example be snap fit under the protruding elements and/or into the fitting portion 9.

Fig. 2a shows how a plurality of bendable arms 4a can be specifically provided in the first embodiment of the plastic carrier 1. The multiple bendable arms 4a extend upward and extend roughly perpendicular to the planar top surface 5a. They point in a direction away from the semicircular bottom surface 7a. The bendable arms 4a extend on opposite sides of the planar top surface 5a, in particular the opposite sides, which are not at the first end face 6a and the second end face 6b, respectively, but rather the opposite sides along the longitudinal extension of the plastic carrier 1. The longitudinal extension of the plastic carrier 1 inserted into a longitudinal tubular lighting tube 3 is shown in Fig. 2b. The bendable arms 4a extend in such a manner from the top surface 5a that they tangentially continue the curvature or radius of the semicircular bottom surface 7a. The bendable arms 4a can be biased by pushing them towards each other before or when inserting the plastic carrier 1 into the lighting tube 3. Then in the lighting tube 3, the bendable arms 4 will push or press in the direction opposite to the direction they were bent in, i.e. against the inner wall of the lighting tube 3 on both sides of the planar top surface 5a. Thus, the plastic carrier 1 is clamped in the lighting tube 3 and a stable position can be achieved.

The pressing of the bendable arms 4a against the inner wall of the lighting tube 3 preferably results in a downward force, i.e. a force pointing from the top surface 5a towards the semicircular bottom surface 7a, so that the semicircular bottom surface 7a is pressed against the inner sidewall of the lighting tube 3. In order to produce such a downward force, the engagement portion of the bendable arms 4a with the inner wall of the lighting tube 3 is preferably in an area above the center plane of the lighting tube 3. That means that the bendable arms 4a will press against the inner walls of the lighting tube 3 at positions, where the lighting tube 3 already tapers above the top surface. Then, a force component is not only directed to the left and right (i.e. in the plane of the planar top surface 5a) , but also directed to the bottom (i.e. to the bottom surface 7a) . The force components press the whole plastic carrier 1 downwards (i.e. press the semicircular surface 7a to the inner walls of the lighting tube 3) .

The plastic carrier 1 can also be shaped according to a second embodiment, which is shown in fig. 5a and 5b. In fig. 5a can be seen that the plastic carrier 1 has a cross-section that resembles a bat. Namely, the plastic carrier has a first end face 6a and a second end face 6b like in the first embodiment. The plastic carrier 1 has a top surface 5b and a bottom surface 7b, wherein the bottom surface 7b is not semicircular as in the first embodiment. Bendable arms 4b extend from the bottom surface 7b in a curved manner, so that their tips approach each other. The radius or curvature of the bendable arms 4a should be larger than the curvature of the lighting tube 3. However, the bendable arms are adapted to be biased before or when being inserted into the lighting tube 3, so that they adapt their curvature to the curvature of the lighting tube 3, and thus press against the inner wall of the lighting tube 3 due to their elasticity. The principle mechanism is the same as described for the first embodiment . The protrusion of the bendable arms 4b from the bottom surface 7b (instead of from the top surface as in the first embodiment) has the effect that the one or more LED modules 2 are arranged closer to the inner wall of the lighting tube 3. A volume between the LED modules 2 and the lighting tube 3 is drastically reduced. This volume can be filled with a matrix material, as will be explained below. By reducing the volume, less material has to be used . In both embodiments of the plastic carrier 1, a plurality of bendable arms 4a, 4b can be arranged in parallel as shown in fig. 2a. That means that along the length of the plastic carrier 1 a plurality of bendable arms 4a, 4b can be arranged on both sides of the top surface 5a, 5b or the bottom surface, respectively. A fixed or varying distance is provided between every tow of the bendable arms 4a, 4b. In any case, the number and position of the plurality of bendable arms 4a, 4b is selected such that there is no torsion acting on the plastic carrier 1, when inserted into the lighting tube 3 and when held by the pressing of the bendable arms 4a, 4b against the inner wall of the lighting tube 3.

As shown in fig. 3a and 3b the plastic carrier 1 (for both embodiments) is provided with a snap connector 8a, 8b on the first end face 6a and the second end face 6b, respectively. Snap connectors 8a and 8b can be designed as male and female parts, respectively, so that they are adapted to engage each other or snap into each other. For example, the plastic carrier 1 can have a female part snap connector 8a at a first end face 6a and a male part snap connector 8b at the second end face 6b. However, the two end faces 6a, 6b can be also provided with identical snap connectors .

The snap connectors 8a, 8b are provided to assist in the longitudinal connection of two plastic carriers 1. This is necessary to produce longer tubular lamps, such as for example to mirror the length of known gas discharge lamps. Therefore, the first snap connector 8a of a first plastic carrier 1 should be shaped such that it is adapted to engage with the second snap connector 8b of a second plastic carrier 1. For example, in fig. 3a and 3b the first snap connector 8a is designed as a recess, gap or cavity in the plastic carrier 1 near the first end face 6a. The second snap connector 8b is, for example, designed as two elements protruding from the second end face 6b, wherein the protruding elements are designed with hook- like tips. The hook-like tips are adapted to snap into the recess or gap, i.e. to engage and grab the recess from opposite sides. The protruding elements are of plastic and are elongate so they are elastic. For snapping onto the recess the protruding elements are firstly bent away from each other, and secondly snap into the recess due to the elastic force tending to bend them back towards each other . In Fig. 4 another possibility to design corresponding snap connectors 8a, 8b is shown. A second snap connector 8b is provided for a first plastic carrier 1, and has two protruding hook-like elements 80b and 81b. A first snap connector 8a on a second plastic carrier 1 has one protruding element 80a having recess portions that are shaped to fittingly receive the hook-like elements 80b and 80a of the second snap connector 8b of the first plastic carrier 1. Again the hook-like elements are elastic and can thus be bent apart and then snap back into the recess portions of the protruding element 80a. The snap connectors can be designed in many ways, as long as they produce a connection that is stable and requires some force to be disengaged, e.g. the elastic force to bend apart the hook-like elements 80b and 81b. A snap connection should prevent a plastic carrier 1 from being able to twist in respect to a second plastic carrier 1, to which it is connected. In particular, the plastic carrier 1 should be blocked by the snap connectors 8a, 8b from twisting around its longitudinal axis. The snap connectors 8a, 8b are a type of mechanical fixing elements, which are integrated with the plastic carrier 1.

A tubular lamp 20 according to the present invention typically comprises a lighting tube 3 and at least one plastic carrier 1 held as explained above by the bendable means 4 inside the lighting tube 3. The design of the plastic carrier 1 has been described in detail above as well. One or more LED modules 2 are mounted on the plastic carrier 1. A tubular lamp 20 can also comprise a plurality of plastic carriers 1, which are connected to each other by their respective snap connectors 8a, 8b as described above. The length of each plastic carrier 1 is preferably in the range of 30 to 40cm. By connecting a plurality of subunits (plastic carriers 1), longer tubular lamps 20 can be assembled. Preferably, the tubular lamp 20 comprises an end seal 10 on each end of its lighting tube 3. The end seals 10 are for sealing the lighting tube 3, and are designed for simply connecting to a plastic carrier 1 inside the lighting tube 3.

A first embodiment of such an end seal 10 is shown in fig. 6a and 6b, respectively. The end seal 10 is comprised of a roughly cylindrical base body 11 with a first end 12a and a second end 12b. The cylindrical base body 11 has portions of different diameter, as will be explained below. The base body 11 is provided at its first end 12a with a snap connector 13 for engaging with a snap connector 8a, 8b provided at one of the ends of a plastic carrier 1. End seals 10 can be connected to the plastic carrier 1 on each end of the lighting tube 3, and can thus provide an easily attachable seal.

The base body 11 and/or the snap connector 13 are preferably made of plastic. Preferably, the material is the same material that is chosen for the plastic carrier 1, which has been specified above. The end seal 10 should have a diameter so that it can be inserted into a lighting tube 3 to be sealed. Therefore, at least the first end 12a of the base body 11 should be of the same or slightly smaller diameter than the diameter of the inner wall of the lighting tube 3. At the second end 12b the end seal 10 should have a portion 17 of increased diameter, so that when the first end 12a is inserted into the lighting tube 3, the second end 12b closes off the lighting tube 3.

The production of a preferred embodiment of the tubular lamp 20 includes that a sealing material and/or a matrix material is inserted into the lighting tube 3. As shown in fig. 6b, the end seal 10 has in the portion 17 of increased diameter at the second end 12b a first through hole 15a. On the other side of the portion 17 of increased diameter an elongate groove 16 continues the channel direction of the first through hole 15a. The groove 16 runs along the length of the end seal 10 on the surface of the base body 11 and passes through a portion 18 of decreased diameter. The first through hole 15a can be used to inject sealing material into the tubular lamp 20, after the end seal 10 has been attached by connecting it to the plastic carrier 1 inside the lighting tube 3. The injected sealing material will flow through the first through hole 15a and subsequently along the base body 11 in the elongate groove 16, and will fill up a sealing space that is defined by the portion 18 of decreased diameter and the inner wall of the lighting tube 3. To evacuate the replaced air from the sealing space, the end seal 10 is further provided with at least one second through hole 15b. The second through hole 15b preferably has a diameter that is smaller than the diameter of the first through hole 15a. The diameter of the second through hole 15b should be chosen small enough that air can be evacuated, but sealing material, for example a silicone, cannot exit the second through hole 15b. The sealing material becomes stuck inside the second through hole 15b due to its viscosity, and seals off the channel. The end seal 10 is preferably further provided with an annular groove 14 for receiving an O-ring. The annular groove trails the circumference of the base body 11. The annular groove 14 crosses the elongate groove 16 preferably perpendicularly. The annular groove 14 is preferably provided closer to the first end 12a of the end seal 10 than the portion 18 of decreased diameter. The received O-ring functions to prevent sealing material from flowing further in direction of the first end 12a, when the sealing space that is defined by the portion 18 of the decreased diameter and the inner wall of the lighting tube 3 is filled up completely.

The end seal 10 further preferably comprises a conduit 19 that runs through the whole base body 11, and connects the first end 12a with the second end 12b. The conduit 19 is shown in fig. 6b by a dashed line. The conduit 19 can be used for injecting a matrix material into the tubular lamp 20, namely into the voids between the plastic carrier 1 and the inner wall of the lighting tube 3. The conduit 19 can be a straight channel through the end seal 10. The channel should have a diameter that is large enough to permit matrix material to be pushed through. The conduit 19 is preferably not in communication (connection) with the through hole 15a or the through hole 15b.

The end seal 10 is further provided with one or more electrical connections that run through the complete base body 11. The electrical connection is for contacting the LED modules 2 that are situated inside the lighting tube 3 to the outside of the tubular lamp 20, when the end seal 10 closes off the lighting tube 3. The electrical connections can be wires that are preferably integrated with or molded into the base body 11. The electrical connections can also run through the conduit 19. The inner wall of the conduit 19 could also be coated with a conducting layer to be the electrical connections. As can be seen in fig. 6a and 6b the snap connector 13 can be made of any number of protruding elements, e.g. three protruding elements 13a, 13b, 13c as shown, wherein e.g. two of the protruding elements 13a, 13b are arranged in parallel and have hook-shaped end parts. These elements 13a, 13b can engage with receiving snap connector elements 8a, 8b of the plastic carrier 1, formed e.g. as recesses. As has been described above, the snap connector 13 is to be designed such that it can engage with a snap connector 8a, 8b of a plastic carrier 1 in an elastic snapping manner. Many configurations are possible, the requirements being that a twisting of the end seal 10 in respect to a plastic carrier 1, to which the end seal 10 is connected, is not possible. Also a certain amount of force should be necessary to disengage the snap connectors, e.g. the force required to bend the protruding elements 13a, 13b apart.

Fig. 7 shows a second embodiment of an end seal 10. The end seal 10b has many features in common with the end seal 10b of the first embodiment. Features can also be combined. The end seal 10 again has a base body 11, a first end 12a, and a second end 12b. The end seal 10 is designed so that a matrix material can be injected into the tubular lamp 20. Therefore the base body 11 has a portion 18 of decreased diameter in its mid section. A first through hole 15a connects the second end 12b with the portion 18 of decreased diameter, wherein the channel direction of the first through hole 15a is continued by an elongate groove 16. A second through hole 15c connects the portion 18 of decreased diameter with the first end 12a, wherein the second through hole 19 continues the channel direction of the elongate groove 16. For attaching to a plastic carrier 1 in the lighting tube 3, the first end 12a is again provided with a snap connector 13 as described above for the first embodiment.

When the tubular lamp 20 is assembled and the end seal 10b closes off the lighting tube 3, a matrix material can be injected into the lamp 20 via the first through hole 15a, the elongate groove 16 and the second through hole 15c. Matrix material will also fill up a sealing space that is defined by the portion 18 of decreased diameter and the inner wall of the lighting tube 3. The matrix material can act as the sealing material, and can glue the end seal 10b to the lighting tube 3. The matrix material and the sealing material can be the same, e.g. can be made from silicones and/or two-component silicones.

In the following a production method of a tubular lamp 20 will be explained. The tubular lamp 20 comprises a plastic carrier 1 as introduced above, one or more LED modules 2, two end seals 10 as described above, and at least one lighting tube 3. Initially, at least one or more LED modules 2 are mounted on the plastic carrier 1. Preferably, the LED modules 2 are not glued to the plastic carrier 1, but are mechanically fixed, for example by a snap fitting. Therefore, the above-described fitting portion 9 is provided on the plastic carrier 1. The plastic carrier 1 is then inserted into a lighting tube 3. For the insertion of the plastic carrier 1, the plastic carrier 1 (or at least a part of the plastic carrier 1) is deformed by bending so that it is biased when inserted into the lighting tube 3. Then, when being arranged inside the lighting tube 3, it presses against the inner wall of the lighting tube 3 and provides a frictional force hold the plastic carrier 1 in place. A part of the plastic carrier 1 that is deformed can, for example, be the bendable arms 4a, 4b as described above.

When the plastic carrier 1 has been arranged in the lighting tube 3, end seals 10 are connected to the snap connectors 8a, 8b of the plastic carrier 1 at each end of the lighting tube 3. In case more than one plastic carrier 1 is used and inserted into the lighting tube 3, end seals 10 are connected to the outmost plastic carriers 1 at the ends of the lighting tube 3. The connection of the end seals 10 to the plastic carrier 1 can be accomplished as described above by suitable snap connectors 8a, 8b, and 13, which are provided at the ends of the plastic carriers 1 and the end seals 10, respectively. One end seal 10 should be equipped with a snap connector adapted to connect to the first snap connector of a plastic carrier 1, and the other end seal 10 should be equipped with a snap connector 13 adapted to connect to the second snap connector 8b of the plastic carrier 1. Finally, when the plastic carrier 1, and the end seals 10, and the at least one lighting tube 3 have been assembled, a matrix material and/or a sealing material are injected through at least one of the end seals 10. The matrix material can, for example, be injected through the conduit 19 of an end seal 10 as described above, in order to fill voids between the LED modules 2 and the inner wall of the lighting tube 3 inside the lighting tube 3. The matrix material can be a material that contains a phosphor so as to change the spectral characteristics of the light emitted from the LED modules 2 and to thus influence the emission characteristics of the tubular lamp 20. The matrix material can contain one or more phosphors for adding light of a different wavelength to the light of the LED modules 2. For example, in order to make emitted blue light perceived as white light, a suitable yellow wavelength can be added by the phosphors.

In case the plastic carrier lb according to the second embodiment is used, the injected matrix material should be prevented from entering the large void between the bendable arms 4b at the bottom surface 7b of the carrier lb. Therefore, the plastic carrier lb of the second embodiment can be provided with suitable sealing means. The sealing means could be provided at the interface of the bendable arms 4b and the bottom surface 7b.

However, it is preferred that the matrix material is allowed to enter any voids that are located between the LED modules 2 and the inner wall of the lighting tube 3 above the top surface 5a, 5b of the plastic carriers 1. If the fitting portion 9, into which the LED modules 2 can be snap fit, is provided with protruding elements as explained above, in order to achieve a more stable snap fit, the matrix material is also allowed to enter any interfaces between these protruding elements and the LED modules 2.

Prior injecting the matrix material, the inner wall of the lighting tube 3 can be coated with a different material that preferably comprises also at least one phosphor. The coating of the lighting tube 3 can be performed before the assembly of the components of the tubular lamp 20. In this way, two layers are established, i.e. the coating layer and the matrix material, which both cover the LED modules 2 and can in combination change the optical characteristics of the tubular lamp 20. Another way to achieve such a double layer is to inject, prior to injecting the matrix material, a filling material into the tubular lamp 20 to selectively cover the inner wall of the lighting tube 3.

The production method can further comprise a step of injecting a sealing material e.g. through the the first through hole 15a of each of the end seals 10 as explained above. As shown in fig. 6b, when sealing material, e.g. silicone, is injected through the first through hole 15a, the sealing material will flow through the elongate groove 16 and will fill up the sealing space, which is defined by the portion 18 of smaller diameter and the inner wall of the lighting tube 3. The sealing material will seal and glue the plastic end seals 10 to the inner wall of the lighting tube 3. Thereby, a protection for the components in the tubular lamp 20 e.g. against dirt and dust is provided. Additional stability of the overall assembly is also provided.

When the sealing material is injected through the first through hole 15a, air will be replaced and will be pushed out through the second through hole 15b, until no air is left in the sealing space. The sealing material will subsequently block the second through hole 15b to seal off the sealing space to the outside.

The two above-described injection steps can be performed subsequently. It does not crucially matter, which of the injection steps is performed first. Preferably, however, the matrix material is filled firstly through the conduit 19 into the voids between the LED modules 2 and the inner wall of the lighting tube 3. Secondly, the sealing material is filled into the sealing spaces on both sides of the lighting tube 3 to close off and seal the tubular 1amp 20.

For performing the injection steps the lighting tube 3 is to be positioned in an upright (vertical) position and the materials are to be injected from the lower side of the upright tubular lamp 20. That means the injected materials are pushed upwards. When the matrix material is pushed in through the conduit 19 of one of the end seals 10 and the lighting tube 3 is in an upright position, the replaced air will be pushed upwards and out from the conduit 19 of the second end seal 10 at the upper end of the lighting tube 3. Thus, it can be ensured that the air is efficiently evacuated and no air pockets develop in the matrix material. The LED modules 2 on the plastic carrier can further be provided with one or more globe tops. Globe tops are preferably dispensed prior to assembling the components of the lamp 20. One globe top can be dispensed over one LED module 2 or can cover a plurality of LED modules 2. A globe top may be dispensed from a material that is transparent and/or from a material that contains one or more phosphors. A globe top is preferably a semispherical accumulation of dispensed material that covers each LED module 2. The globe top thus protects the LED module 2 and can be used to alter the light emission characteristics of each LED module 2.

The one or more globe tops also serves to distance the injected matrix material slightly from the light producing surface of the one or more LED dies that are contained in each LED module 2. Thus, the requirements as to the heat stability of the matrix material or of the phosphors in the matrix material are lowered, since the heat is not directly produced at the matrix material interface. Heat from the LED modules 2 will be carried away by the plastic carrier 1 that acts as a heat sink, and by the globe top material that absorbs the heat directly from the LED modules 2, before giving secondary heat off to the matrix material.

The heat transfer in the tubular lamp 20 is optimized by the design the plastic carrier 1 as has been described above. An efficient heat sink that transfers heat to the lighting tube 3 is provided, without the necessity of providing a separate aluminum heat sink. By injecting the matrix material, a large area surface contact between the inner wall of the lighting tube 3 and the plastic carrier 1 and the LED modules 2, respectively, is formed. This leads to a more efficient cooling and heat sinking of the matrix material. The matrix material 1 also provides extra stability to the tubular lamp 20. The production of the tubular lamp 20 is simple and can be adapted to the production of lamps 20 with different lengths easily.