LED module with surge current protection

Abstract

The present invention relates to an LED module comprising: at least two LEDs connected in series and arranged on a printed circuit board (PCB), the printed circuit board comprising two terminals for electrical supply from a driver to the LEDs; a surge current protection structure, the surge current protection structure comprising: a first metal surface disposed on the PCB and connected to anode potential energy of the LEDs connected in series; and a second metal surface arranged on the PCB and connected to the cathode potential energy of the LEDs connected in series, furthermore, the first metal surface and the second metal surface are respectively connected in a thermally conductive manner with each LED of the LEDs of the first group of LEDs at the anode potential energy side of the LEDs connected in series, and the first metal surface and the second metal surface are respectively connected in a thermally conductive manner with each of the LEDs of the second group of LEDs at the anode potential energy side of the LEDs connected in series. And each LED in the second group of LEDs at the cathode potential energy side of the LEDs connected in series is connected in a thermally conductive manner.

Description

Technical Field

[0001] The present invention relates to an LED module. In particular, the present invention relates to an LED module with surge current protection, and to a system including such an LED module and a driver for supplying electricity to the LED module. Background Art

[0002] The 230V AC power grid may be subject to different disturbances, such as surge disturbances, which may be harmful for lighting applications. Two different types of such disturbances are known: so-called differential mode surges and so-called common mode surges. Differential mode surges (between the L and N conductors) are relevant for LED driver protection circuits, whereas common mode surges (from L+N towards the PE, ground, conductors) are able to bypass the LED driver, even SELV LED drivers, due to the presence of main / auxiliary capacitors inside the LED driver. The main / auxiliary capacitors are used for the EMC (Electromagnetic Compatibility) requirements imposed on LED drivers.

[0003] Common mode surges can damage LED components through reverse bias overvoltage junction breakdown. Precautions should be taken to avoid these damages.

[0004] In the case of an aluminum core PCB assembly and / or heat sink, the PE conductor is very close to the LED. For example, WO2015124520A1 in Figure 3 illustrates a discharge path activated when a common mode surge occurs. In addition, in the front page, WO2015124520A1 shows a specific implementation of a ceramic capacitor for bypassing the LED component.

[0005] However, ceramic capacitors are expensive to manufacture. In addition, lighting equipment containing aluminum core PCBs and / or heat sinks may be very sensitive to common mode surge interference.

[0006] It is therefore an object to provide an improved LED module which avoids the above mentioned disadvantages. Summary of the invention

[0007] The objects of the invention are achieved by the solutions provided in the attached independent claims. Advantageous embodiments of the invention are further defined in the dependent claims.

[0008] According to a first aspect of the present invention, an LED module is provided.

[0009] The LED module includes at least two LEDs connected in series and arranged on a printed circuit board PCB, the printed circuit board including two terminals for supplying electricity from a driver to the LEDs. In addition, the LED module includes a surge current protection structure, which includes: a first metal surface, which is arranged on the PCB and connected to the anode potential of the LEDs connected in series; and a second metal surface, which is arranged on the PCB and connected to the cathode potential of the LEDs connected in series. In addition, the first metal surface and the second metal surface are respectively connected in a thermally conductive manner to each LED of the first group of LEDs at the anode potential side of the LEDs connected in series, and are connected in a thermally conductive manner to each LED of the second group of LEDs at the cathode potential side of the LEDs connected in series.

[0010] This provides the advantage that the incident surge impulse is discharged in a controlled manner.

[0011] In a preferred embodiment, each of the first metal surface and the second metal surface has the same surface within a margin of 10%, preferably 5%.

[0012] In a preferred embodiment, the surface of the first metal surface or the second metal surface is at least the footprint surface of the LED, preferably at least 200% of the footprint surface, more preferably at least 300% of the footprint surface.

[0013] In a preferred embodiment, the first metal surface and the second metal surface comprise copper.

[0014] In a preferred embodiment, the LED module further comprises a back side of the PCB board, which is designed to serve as a common capacitor electrode for the first metal surface and the second metal surface.

[0015] In a preferred embodiment, the back side of the PCB includes a heat sink.

[0016] In a preferred embodiment, the LED module comprises an even number of LEDs, and wherein a surface of the first metal surface and a surface of the second metal surface are substantially identical.

[0017] In a preferred embodiment, the LED module comprises an odd number of LEDs. In this case, the surface area of ​​the second metal surface can also be made equal to the surface area of ​​the first metal surface by adjusting the size of the corresponding copper area.

[0018] According to a second aspect, the invention relates to a system comprising a driver and an LED module according to the first aspect and any one of the preferred embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be explained below with reference to the accompanying drawings.

[0020] Figure 1 An embodiment of a system including a driver and an LED module is shown; and

[0021] Figure 2 An embodiment of a system including a driver and an LED module is shown. DETAILED DESCRIPTION

[0022] Aspects of the invention are described herein in the context of a system including an LED driver and an LED module.

[0023] Figure 1 and Figure 2 A system 100 including a driver 200 and an LED module 101 according to an embodiment is shown, wherein Figure 1 is a side view of system 100, and Figure 2 is a top view of system 100 .

[0024] The LED module 101 includes at least two LEDs D1, D2, D3, D4, D5, D6 connected in series and arranged on a printed circuit board PCB. The printed circuit board includes two terminals 1, 2 of a connector 102 for supplying electricity from a driver 200 to the LEDs D1, D2, D3, D4, D5, D6. The LED module 101 is connected to the driver 200 via the connector 102. In addition, the LED module 101 includes a surge current protection structure, which includes: a first metal surface 103 arranged on the PCB and connected to the anode potential of the LEDs D1, D2, D3 connected in series; and a second metal surface 104 arranged on the PCB and connected to the cathode potential of the LEDs D4, D5, D6 connected in series. In addition, the first metal surface 103 and the second metal surface 104 are respectively connected to each LED D1, D2, D3 of the first group of LEDs D1, D2, D3 at the anode potential side of the LEDs connected in series in a thermally conductive manner, and are thermally connected to each LED D4, D5, D6 of the second group of LEDs D4, D5, D6 at the cathode potential side of the LEDs connected in series in a thermally conductive manner.

[0025] In such LED modules 101 , LEDs each having three connectors may be used, one connector for the anode, one connector for the cathode, and the third connector intended to remove heat from the LED module 101 .

[0026] The first metal surface 103 or copper pad on the circuit board to which the third connector is connected is relatively large compared to the surface of the connection for the electrical supply to the LEDs, in order to ensure that a sufficient amount of heat is removed from the LED module 101. According to the invention, these areas with copper and connected to the LEDs can be advantageously used and designed with respect to their electrical potential in order to build up a capacitance capable of covering surge bursts instead of dedicated capacitors.

[0027] The back side 105 of the circuit board (eventually equipped with a heat sink) is the entry point for the surge pulse. The surge pulse can be transmitted to the front copper area of ​​the circuit board through capacitive coupling. The back side 105 of the circuit board serves as a common electrode for all capacitors.

[0028] The copper areas (or the first metal surface 103 and the second metal surface 104) that establish the two electrodes of the capacitor can have similar sizes so that an equal distribution of the positive connection copper area and the negative connection copper area can be achieved. Therefore, the layout should be adjusted to ensure that each of the two groups of copper areas can provide 50% of the entire area. In the case where there are through holes, etc. on the LED module 101, the size is set accordingly. In the case where there is an even number of LEDs, the distribution of the copper areas can be equal. However, there may even be an odd number of LEDs if the size of the corresponding copper areas is adjusted.

[0029] 50% of the area is connected on one side to the LED positive terminal of connector 102 and on the other side to the LED negative terminal of connector 102 so that a capacitance is formed by these two groups. The magnitude of the resulting capacitance is smaller than that of capacitors used in the prior art.

[0030] The present invention has the advantage that a synergistic effect is achieved, which avoids additional components and thereby reduces the cost of the entire LED module 101 without any loss of performance.

[0031] Reference numerals list

[0032] 1 terminal

[0033] 2 terminals

[0034] 100 Systems

[0035] 101 LED Module

[0036] 102 Connectors

[0037] 103 First Metal Surface

[0038] 104 Second metal surface

[0039] 105 Back side of PCB

[0040] 106 common electrode

[0041] 107 Isolation Layer

[0042] 200 Drivers

[0043] D1,……,D6 LED

Claims

1. An LED module (101), comprising: - at least two LEDs (D1, D2, D3, D4, D5, D6) connected in series and arranged on a printed circuit board PCB, the printed circuit board comprising two terminals (1, 2) for electrical supply from a driver (102) to the LEDs (D1, D2, D3, D4, D5, D6); - a surge current protection structure, the surge current protection structure comprising: - a first metal surface (103) arranged on the PCB and connected to the anode potential of the LEDs (D1, D2) connected in series; and - a second metal surface (104) arranged on the PCB and connected to the cathode potential of the LEDs (D1, D2, D3, D4, D5, D6) connected in series, In addition, the first metal surface (103) and the second metal surface (104) are respectively connected to each LED (D1, D2, D3) of a first group of LEDs (D1, D2, D3) at the anode potential side of the LEDs (D1, D2, D3, D4, D5, D6) connected in series in a thermally conductive manner, and are connected to each LED (D4, D5, D6) of a second group of LEDs (D4, D5, D6) at the cathode potential side of the LEDs (D1, D2, D3, D4, D5, D6) connected in series in a thermally conductive manner.

2. The LED module (101) according to claim 1, wherein each of the first metal surface (103) and the second metal surface (104) has the same surface area within a margin of 10%, preferably 5%.

3. The LED module (101) according to claim 1 or 2, wherein the surface of the first metal surface (103) or the second metal surface (104) is at least the footprint surface of the LED, preferably at least 200% of the footprint surface, and more preferably 300% of the footprint surface.

4. The LED module (101) according to any one of the preceding claims, wherein the first metal surface (103) and the second metal surface (104) comprise copper.

5. The LED module (101) according to any one of the preceding claims, further comprising a back side (105) of the PCB board, the back side being designed as a common capacitor electrode (106) for the first metal surface (103) and the second metal surface (104).

6. The LED module (101) according to claim 5, wherein the back side (106) of the PCB comprises a heat sink.

7. The LED module (101) according to any one of the preceding claims, wherein the LED module (101) comprises an even number of LEDs (D1, D2, D3, D4, D5, D6), and wherein the surface area of ​​the first metal surface (103) and the surface area of ​​the second metal surface (104) are substantially equal.

8. The LED module (101) according to any of the preceding claims 1 to 6, wherein the LED module (101) comprises an odd number of LEDs (D1, D2, D3, D4, D5, D6).

9. A system (100) comprising a driver (200) and an LED module (101) according to any one of the preceding claims, wherein the LED module (101) is connected to the driver via a connector (102) and the driver (200) supplies electricity to the LED module (101).

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