NL2003481C2

NL2003481C2 - Improved led arrangement and lamp assemblies.

Info

Publication number: NL2003481C2
Application number: NL2003481A
Authority: NL
Inventors: Yu-Chou Houng; Peter Zwaan
Original assignee: Ec Vastgoed B V; Yu-Chou Houng
Priority date: 2008-10-24
Filing date: 2009-09-14
Publication date: 2010-11-23
Also published as: EP2180235A1; NL2003481A1

Description

Improved LED arrangement and lamp assemblies

The present invention relates to a LED arrangement for use in a lamp assembly, to the lamp assembly comprising a number of such 5 LED arrangements and to further lamp assemblies.

The object of the invention is to provide a LED arrangement allowing to have a more efficient focused radiation pattern with a radiation angle which is adaptable.

10

To reach this object, the LED arrangement according to the invention is distinguished by comprising: - a light emitting diode for emitting an amount of light; - a guide structure arranged above the light emitting diode, the 15 guide structure having an input section directed towards the light emitting diode and an output section, wherein the guide structure is designed for grouping substantially the complete amount of light within a certain radiation angle; and preferably - a lens mounted at the output side of the guide structure, said 20 lens being arranged for providing efficient focusing of the light entering the lens.

Advantageous embodiments of the invention are disclosed in claims 2-16.

25

According to a preferred embodiment the guide structure is a hollow metal tooling with an adapted shape, preferably made from copper. The guide structure has for example a conical input section narrowing in the direction away from the light emitting 30 diode, and a conical output section narrowing in the direction away from the lens. In that way the light can leave the tooling according a specific radiation pattern with a wide or narrow angle depending on the location to be lit.

35 According to a further developed embodiment the conical output section has a center line, and an outer surface making an angle with the center line, wherein the angle lays between 2 degrees and 85 degrees depending on the required radiation pattern of 2 the arrangement. For an angle of 2 degrees a narrow spot will be lit, while for an angle of 85 degrees a large area will be lit. According to an exemplary embodiment the conical output section can be asymmetric, wherein the angle varies so that an 5 asymmetric radiation pattern is obtained.

Preferably the guide structure is substantially diabolic. This provides for a very efficient and compact guiding of the light 10 According to a further aspect of the invention the lens has a substantially flat base with dimensions which correspond substantially with the dimensions of the output section of the guide structure. The lens is preferably fixed on the guide structure using a glue, in particular an epoxy glue.

15

The invention further relates to a lamp assembly comprising a lamp body and a number of LED arrangements according to the invention, said number of LED arrangements being fixed in the lamp body for obtaining a certain total light pattern of the lamp 20 assembly. According to a preferred embodiment the body is a tube-like body which is provided with lamp caps and electrode pins according to the same international standards as common lamp tubes.

25 Conventional LED light is generally configured by directly mounting a control wiring board into a space formed by a circular tube made of plastic, or into a closed space formed by a base and a cover. The PCB is suspended or directly set within the base. Control elements of the LED light are provided in the lower 30 portion of the PCB. Heat elimination from the PCB to the outside is by means of thermal conduction by air. The difficulty in heat elimination of the LEDs is a problem. Accordingly, the life of the LEDs is shortened due to the excessively high temperature of the LED.

Another purpose of the invention is to provide a lamp assembly with a good heat elimination performance, a simple configuration, 35 3 a good illumination performance, a small size, a low cost and also a good appearance.

This is achieved by a lamp assembly comprising a tube shaped lamp 5 body and a plurality of LEDs being fixed on a PCB in the lamp body, said lamp body comprising a metal lower part, and a transparent cover part, said metal lower part being arranged for transporting the heat of the plurality of LEDs to the outside.

10 According to a preferred embodiment the PCB is mounted on the metal lower part with insertion of a heat conducting, electrically insulating layer, for example a layer of the silicon type.

15 A.ccording to a preferred embodiment the lower part is made of aluminum or an aluminum alloy and the cover part is made from PC. The lower part and the cover part preferably extend over substantially the complete length of the tube like body and have substantially a semi-circular cross section. The cover part and 2 0 the lower part can further be adapted so that the cover part can be snap-fitted on the lower part.

According to a further developed embodiment the lower part is provided with ribs to improve cooling thereof and at the same 25 time strengthen the lower part.

According to another aspect of the invention the lamp assembly comprises a main body, said main body being constituted by a metal base, a transparent cover mounted on the metal base, a PCB 30 provided within the metal base, and an LED light provided on the PCB, wherein a heat-conductive and electrical-insulated layer is attached in a heat-conductive way between the bottom surface of the PCB and the metal base.

In said lamp assembly, the overall profile of the main body may 35 be a long tube shape.

In an embodiment of the lamp assembly, the cross section profile of the main body may be circular or rectangular.

4

In an embodiment of the lamp assembly, there may be lamp holders provided on the both ends of the main body.

5 In an embodiment of the lamp assembly, cross sections of the metal base and the transparent cover are half circles which buckle with each other in a symmetric way, and an integral fitting plate is provided in the metal base, the PCB and the heat-conductive and electrical-insulated layer which are attached with each other 10 being fixed on the fitting plate.

In an embodiment of the lamp assembly, control elements of the LED lights are provided on both end portions of the PCB within the lamp holders.

15

With the above described configuration according to the invention, the heat-conductive and electrical-insulated layer made of silicon material provided between the PCB and the metal base enables the heat of the PCB to be directly conducted to the 20 metal base using the fact that the metal base are able to rapidly conduct heat, and therefore the temperature inside the light body is significantly decreased. In addition, the metal base and the transparent cover constitute the main body in a long tubular shape, with the profile of the cross sections being in a circular 25 shape, which enables the effective use of the spaces in the lamp holders on both ends for accommodating the control elements, and therefore the overall appearance is good and the configuration is compact. Furthermore, the corresponding transparent cover has a cross section in a half circle shape, which enhances the 30 illuminating performance and focusing performance.

The accompanying drawings are used to illustrate presently preferred non-limiting exemplary embodiments of the present invention. The above and other advantages, features and objects 35 of the invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with accompanying drawings in which: 5

Figure 1 is a schematic longitudinal section of an embodiment of a lamp assembly according to the invention;

Figure 2 is a schematic perspective view of the first embodiment, 5 partly exploded;

Figure 3 is a cross section along line A-A of figure 1;

Figure 4 is a cross section of a second embodiment of a lamp 10 assembly of the invention;

Figure 5 is a perspective view of an end cap of the first embodiment; 15 Figure 6 is an example of the driver circuit for powering the LED components of a lamp assembly according to the invention;

Figure 7 is a detailed schematic drawing of an embodiment of a LED chip mounting according to the invention; 20

Figure 8(A)-(C) illustrate schematically how the radiation pattern of the emitted light of a LED can be changed with an embodiment of the invention;

25 Figures 9-11 illustrate a method for preparing a number of LED

arrangements of the invention in a number of rows for mounting on a PCB.

Figures 1 to 3 illustrate an embodiment of a lamp assembly 30 according to an embodiment of the invention. The embodiment of figure 1 comprises a cylindrical tube-like body 1 typically with the dimensions of a standard fluorescent tube (TL-D). The tube-like body consists of two parts: an aluminum-alloy lower part 11 and a cover part 12, typically fabricated from a PC 35 (Polycarbonate) material. The aluminum-alloy lower part is provided with a support part 11a. Cross sections of the metal base 11 and the transparent cover 12 are half circles which buckle 6 with each other in a symmetric way, and the support part is here an integral fitting plate 11a provided in the metal base 11.

In the tube-like body 1 there are provided a number of LED 5 components 14 which are here arranged in three rows. The skilled person will understand that this can be any number of rows depending of the dimensions of the lamp assembly, the required lighting, the dimensions of the LED components, etc.

10 The LED components are mounted on a printed circuit board (PCB) 13. The PCB 13 is supported on the lower part 11 with the intersection of a layer 15 for electric isolation on the one hand and heat transport on the other hand between the PCB 13 and the lower part 11. Layer 15 is for example fabricated in a silicon 15 type of material.

The heat-conductive and electrical-insulated layer 15 is attached in a heat-conductive way between the bottom surface of the PCB 13 and the fitting plate 11a of the metal base 11. The 20 PCB 13 and the heat-conductive and electrical-insulated layer 15 which are attached with each other are fixed on the fitting plate 11a.

The end parts of the body 1 are closed with end caps 16. The end 25 caps 16 are for example adapted for lamp holders of the T8-type. A detailed perspective view of such an end cap 16 is shown in figure 5. The end cap basically consists of an end part 19 and two fixation sections 17, 18 extending inwardly in the body 1. A first fixation section 17 which can be fitted in the cover part 30 12 and a second fixation section 18 which can be fitted in the lower part 11.

Note that the lower part 11 is preferably fabricated in a material with good heat transport properties, but this material can be 35 different from aluminum or an aluminum alloy. As shown in the figures the lower part can be provided on its outside surface with a corrugated profile in order to further improve cooling of the lamp assembly.

7

The parts 15 schematically represent components of a driver circuit (i.e. a constant current power unit) for the LED components 14 on the PCB 13. An example of such a driver circuit 5 is shown in figure 6. The control elements 15 can be provided on both end portions of the PCB 13 partly within the end caps 16.

Fig. 4 shows an LED fluorescent tube according to the second 10 embodiment, which comprises a long tube shaped main body 1. The main body 1 is constituted by a long channel-shaped metal base 11, a transparent cover 12 mounted on the metal base 11, a PCB 13 provided within the metal base 11, and an LED light 14 provided on the PCB 13. A cross section of the metal base 11 is in a 15 rectangular shape, and a cross section of the transparent cover 12 is in a half circular shape. A heat-conductive and electrical-insulated layer 15 is attached in a heat-conductive way between the bottom surface of the PCB 13 and an inner wall surface of a bottom plate of the metal base 11. The 20 heat-conductive and electrical-insulated layer 15 is made of silicon. End caps 16 are provided on both ends of the main body 1. Control elements of the LED light 14 are provided on both end portions of the PCB 13. When the fluorescent tube is in use, the main body 1 is fitted in a lamp holder via connection pins 25 on external end portions of the lamp holders.

Now the details of an embodiment of a LED arrangement will be set out in detail with reference to figure 7. A LED chip 20 is mounted on a base, typically inside a cup 25 of a stent as is 30 known in the art. The light emitted by the LED chip is bundled via a hollow metal guide structure 21, preferably in the form of diabolic metal tooling, for example made in copper. A lens 23 is fixed on the guide structure 21 preferably using an epoxy glue 24. The form of the guide structure should be adapted to 35 group substantially all the light emitted by the LED chip and to guide the light within a certain radiation angle before entering the lens 23.

8

As shown in figure 8(A) the opening angle 01 of the output section of the guide structure 21 can be varied in function of the desired radiation pattern. Further the base dimensions of the lens 23 can be adapted accordingly. Figure 8(B) shows an embodiment 5 with a small opening angle CCl for obtaining a narrow spot of light while figure 8 (C) shows a wide opening angle 0c2 for obtaining a larger lit area.

Finally figures 9-11 illustrate how the LED arrangement shown 10 in figure 7 is prepared for mounting in a number of rows on a PCB 13. Figure 9 is a top view of the stents and connection lines used for connecting the LED arrangements 20-24 on the PCB 13. The numbers 26 and 27 refer to the stents for connecting a LED placed in cup 25 with the positive and negative side of the power 15 supply. Reference 29 refers to further connection lines for connecting the different LEDs. The metal is cut where necessary after packaging of the LEDs. The housing 30, 30' placed over the stents is shown in figures 10 and 11. The height of the cap-like housing 30, 30' is chosen in function of the radiation 20 angle, and figure 10 shows a housing for a total radiation angle of 75/80 degrees while figure 11 shows a variant for a total radiation angle of 25/30 degrees with a higher housing 30'. Figures 10 and 11 further show a stop element 32 for holding the stents 27, 28. Element 33, 33' is a module article with a first 25 side on which the LEDs are mounted and a back side on which the stop elements 32 are mounted.

While the principles of the invention have been set out above in connection with specific embodiments, it is to be clearly 30 understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.

Claims

A lamp assembly comprising a tubular lamp body and a number of LEDs mounted on a printed circuit board (PCB) in the lamp body, characterized in that the lamp body comprises a metal lower part and a transparent cover part, which metal lower part is adapted to transporting the heat from the number of LEDs to the outside.

2. Lamp assembly according to claim 1, characterized in that the lower part is made of aluminum or an aluminum alloy.

3. Lamp assembly as claimed in claim 1 or 2, characterized in that the printed circuit board is mounted on the metal lower part with the insertion of a heat-conducting, electrically insulating layer.

4. A lamp assembly as claimed in any one of claims 1-3, characterized in that the heat-conducting, electrically insulating layer is of the silicon type.

5. Lamp assembly as claimed in any of the claims 1-4, characterized in that the lower part and the cover part extend over substantially the full length of the tubular body.

6. Lamp assembly as claimed in any of the claims 1-5, characterized in that the cover part is made of PC.

7. Lamp assembly as claimed in any of the claims 1-6, characterized in that the cover part is snapped onto the lower part.

8. A lamp assembly according to any one of claims 1-7, characterized in that the lower part is provided with ribs to improve cooling of the lower part.

An LED fluorescent tube comprising a main body (1), which main body (1) consists of a metal base (11), a transparent cover (12) mounted on the metal base (11), a printed circuit board (13) which is provided in the metal base 35 (11), and an LED lighting (14) provided on the printed circuit board (13), characterized in that a heat-conducting and electrically insulating layer (15) is attached in a heat-conducting manner between the bottom surface of the printed circuit board (13) and the metal base (11).

LED fluorescent tube according to claim 9, characterized in that the general profile of the main body (1) is a long strip shape 5.

LED fluorescent tube according to claim 9, characterized in that the cross-sectional profile of the main body (1) is circular or rectangular.

12. LED fluorescent tube according to claim 9, characterized in that 10 lamp holders (16) are provided at both ends of the main body (1).

13. LED fluorescent tube according to any one of claims 9-12, characterized in that the cross-sections of the metal base (11) and of the transparent cover (12) are semicircles that can be locked together in a symmetrical manner, and that an integral support plate (11a) is provided in the metal base (11), the printed circuit board (13) and the thermally conductive and electrically insulating layer (15) interconnected with each other being mounted on the support plate (11a).

LED fluorescent tube according to one of claims 9-13, characterized in that control elements of the LED lighting (14) are provided on both end portions of the printed circuit board (13) in the lamp holders (16).

15. Lamp assembly as claimed in any of the foregoing claims, comprising a number of LED devices comprising: - a light-emitting diode for emitting an amount of light; - a metal guide structure disposed above the light-emitting diode, which guide structure has an input section facing the light-emitting diode and an output section, the guide structure being designed to substantially group the entire amount of light within a certain beam angle.

The lamp assembly of claim 15, further comprising: a lens mounted at the exit side of the guide structure, which lens is adapted to provide effective focusing of the light entering the lens.

A lamp assembly according to any one of claims 15-16, characterized in that the guide structure is a hollow metal equipment with a modified shape.

18. A lamp assembly as claimed in claim 17, characterized in that the guide structure is a hollow tubular section with a variable diameter, such that the input section is adapted to the dimensions of the light-emitting diode and that the output section is adapted to the required beam angle.

19. A lamp assembly according to any one of claims 15-18, characterized in that the guide structure is made of copper.

20. A lamp assembly as claimed in any one of claims 15-19, characterized in that the guide structure has a conical input section which narrows in the direction away from the light-emitting diode.

A lamp assembly as claimed in any one of claims 15-20, characterized in that the guide structure has a conical exit section that narrows in the direction away from the lens.

22. Lamp assembly as claimed in claim 21, wherein the conical exit section has a center line and an outer surface which makes an angle with the center line, characterized in that the angle is between 2 degrees and 85 degrees depending on the required radiation pattern of the device .

23. Lamp assembly as claimed in claim 21 or 22, wherein the conical exit section has a center line, and an outer surface 25 which makes an angle with the centerline, characterized in that the conical exit section is asymmetrical, the angle varying such that an asymmetrical radiation pattern is obtained is becoming.

24. A lamp assembly according to any one of claims 15-23, characterized in that the guide structure is substantially in the form of a diabolo.

A lamp assembly according to any one of claims 15 to 24, characterized in that the lens has a substantially flat base with dimensions that substantially correspond to the dimensions of the exit section of the guide structure.

26. A lamp assembly as claimed in any one of claims 15-25, characterized in that the lens is mounted on the guide structure using an adhesive, in particular an epoxy adhesive.

27. A lamp assembly according to any one of claims 15-26, characterized in that the number of LED devices is arranged according to a number of rows.

28. A lamp assembly as claimed in claim 27, characterized in that the body is a tubular body provided with lamp-end caps and electrode pins according to the same international standards as the conventional lamp tubes.

29. A lamp assembly according to any one of claims 26-28, characterized in that a driving circuit is provided for the number

10 LED device in the body.