EP2716960A2 - Light module - Google Patents

Abstract

The illumination module (1) has a light source and a power connection for supplying the light source. The illumination module has a cooling element (8). The light sources are arranged at a front side of a circuit board (6). The cooling element is connected with a rear side of the circuit board. The cooling element is attached to the circuit board by an adhesive. The illumination module has a cover (7), which is made of plastic or metal. An independent claim is included for a chain of lights with two illumination modules connected in series.

Description

The invention relates to a light module for a light chain and a light chain with such a light module, in particular for use in light boxes.

DE 10 2004 004 777 A1 discloses a deformable light chain with a plurality of lighting modules, on each of which at least one optical emitter is arranged and which are connected via two electrical power supply wires to a chain. The electrical power supply wires run without interruption across all modules of the chain and interconnect the modules.

US 6,566,824 B2 discloses a lighting device having a lighting segment comprising a plurality of lighting sections. Each of the sections includes a circuit board with a semiconductor light emitter mounted thereon. The sections are interconnected by board connectors which connect the boards to edges of adjacent boards in close proximity to one another. The board connectors are deformable to change the orientation in response to an applied force. The sections are electrically connected together so that the semiconductor light emitters are electrically connected in series. The segment has a current regulator that regulates the current through the semiconductor light emitter.

It is the object of the present invention to provide a possibility for more uniform and reliable illumination, in particular backlighting of illuminated areas, by means of light chains.

This object is achieved by a light module and a light chain according to the respective independent claim. advantageous Embodiments are in particular the dependent claims.

The light module for a light chain has at least one light source and at least one power connection for supplying the at least one light source. Furthermore, the light module has a heat sink.

By integrating the heat sink in the light module this is better cooled, whereby a lifetime is extended. Further, a user no longer needs to worry about cooling the luminescent chain, or increases the user-friendliness. This applies in particular to accommodation of the light chain in a so-called light box, in which a uniform backlighting of illuminated areas (for example advertising boxes or illuminated letters) results in improved and simplified cooling and thus increased reliability.

The lighting modules are preferably connected so that a power loss of a driving or driving circuit for the light sources distributed substantially uniformly on the lighting modules. The light-emitting module, which is suitable in particular for use in the light chain, has for this purpose in particular at least one continuous light source line with at least one intermediate light source, in particular with at least one light-emitting diode. By continuous is understood here in particular an electrical line, which has at least one input and one output terminal on the light module, that is passed through the light module. The light-emitting module furthermore has at least one continuous light source supply line for the power supply of the light source and at least one continuous driver supply line for operating at least one driver circuit for controlling the at least one light source. A driver circuit feeds the at least one continuous driver supply line.

Preferably, the light sources are disposed on a front side of a board, and the heat sink is connected to a back side of the board.

Preferably, the heat sink is attached to the board by means of an adhesive. The adhesive is preferably a thermally conductive adhesive compound and may be electrically conductive or insulating as needed.

Alternatively, the heat sink can be fastened to the circuit board by means of a mechanical connection element, wherein an intermediate layer of TIM material is preferably arranged between the heat sink and the circuit board.

A luminous module in which the heat sink has retaining tabs for fastening the luminous module is preferred. In this case, the heat sink is preferably formed in an elongated shape. The shape of the heat sink preferably corresponds to the board dimensions. The retaining tabs then preferably begin at a side edge in the region of the center of the associated longitudinal axis. As an elongate shape, for example, an oval, a polygonal or a rectangular basic shape, or hybrids thereof, can be used, wherein the contour of the side edges thereof may differ locally. However, heat sink and / or board are not limited to an elongated shape, but may be arbitrarily shaped, for. B. in round or square shape. Also, the retaining tabs can be located in any position.

The cooling body preferably has an arrangement of cooling projections, in particular cooling pins, for effective cooling. It is particularly preferred if the height of the retaining tabs is smaller than the height of the cooling projections, in particular pins. Particularly preferred is a lighting module in which the retaining tabs and the cooling projections, in particular pins, have a height difference between about 0.05 and about 0.3 mm.

Further preferred is a light-emitting module in which the heat sink is made of aluminum, in particular of aluminum with a purity of more than 95%, especially of over 98%. Generally, the heat sink may consist of a material of high thermal conductivity, for. B. using copper, zinc and / or magnesium. Specifically, the heat sink on a patch on a plate arrangement of regularly arranged pins of the same height.

The heat sink is preferably surface treated to increase the thermal emissivity, e.g. B. coated or anodized.

To improve the optical properties and the heat radiation, the heat sink has a bright color with high light reflectance.

The light module can one or more monochrome, z. B. white, light sources. The light module preferably has a red light-emitting diode, a blue light-emitting diode and two green light-emitting diodes.

The light sources are preferably light-emitting diodes, but may also include other types of light sources such as incandescent or fluorescent lamps and so on.

The light module can for some or all light sources mounted on it have a common look, in particular scattering optics, z. B. a common scattering lens. However, it is particularly preferred for reducing the installation height if each light source is assigned its own scattering optics for scattering the light emitted by the respective light source. Instead of a scattering lens, any other suitable Light scattering element can be used. The scattering lens is preferably broadly scattering, z. B. a so-called. ARGUS lens, so that a largely uniform light emission results even at low height.

To increase the efficiency, a coupling-out optics can also be used.

A luminous module in which the circuit board or the substrate or the construction technology has a good thermal conductivity or low thermal resistance is preferred. Particularly preferred is a lighting module in which the board is a metal core board.

It is preferred if the light-emitting module has a cover at least for covering the circuit board. In order to improve the uniformity of a light emission, in particular of light boxes, the lid has on the outside a reflectivity of more than 60% in the visible range of the light. It is preferred that the lid is formed so that it covers the heat sink at least partially laterally in the mounted state. The lid can be made of plastic or metal. It may be preferred, in particular when used in Innräumen, when the lid does not hermetically seal an underlying interior of the lighting module in the mounted state. Advantageously, electrical contacts of live parts on the board are then coated with a lacquer layer for mechanical protection and corrosion protection, in particular with a lacquer which when applied has a viscosity in the range of 100-3000 mPas in order to distribute uniformly opaque.

For use as a non-terminal (middle) chain link of the light chain, the lighting module has at least two electrically connected electrical connections for supplying the at least one light source. These power connections are usually powered by a single power source and represent parts of an electrically continuous power line.

For flexible color selection of the (total) light emitted by the light module, preferably at least one external voltage source is used whose voltage can be pulse width modulated.

The object is also achieved by means of a luminous chain with at least two series-connected lighting modules.

Preferably, the associated lighting modules are connected so that a set of light sources, each comprising a light source of the lighting modules, is electrically connected in series, d. h., By means of a so-called strand. It is then particularly preferred if the lighting modules are connected in such a way that a set of light sources of the same color, each comprising a light source of the lighting modules, is electrically connected in series.

Particular preference is given to differently colored light sources or light sources with associated optics, which can produce a white light in additive color mixing. This may be, for example, a combination of array RGB light sources, but also RRGB, RGGB, RRGGB, and so on. By different colored light sources can also be achieved by suitable control a light output of the light module with variable, specifically adjustable color.

A light chain of such light modules has a plurality of above-mentioned lighting modules above, wherein at least one light module, in particular a terminal light module, the light source supply line and the light source line are electrically connected to each other. In this light module is thereby guided over the light source supply line (accumulated) sum of the Driver (part) circuits in the light source in the line-connected light sources fed.

In another aspect, at least two of the lighting modules of the light chain each have at least one set of at least one light source and a driver circuit for controlling the at least one light source. The driver circuits of a set of the respective lighting modules are electrically connected to each other in parallel, and the light sources of this one set ("string") of the respective lighting modules are electrically connected to each other in series. The driver outputs of the driver circuits are merged at a node for common power supply of all light sources of this one set.

It is advantageous if the driver circuit has an electrical resistance and / or at least one transistor and / or at least one diode. It is also advantageous if the driver circuit is a current control circuit, in particular a Stromkonstanterschaltung. The driver output is advantageously, but not necessarily, a current output.

It is advantageous for a simple construction, if the driver circuit is electrically connected to one of its supply inputs with a cathode side of the associated, so on the same light module, light source, as this results in a higher potential difference than in the connection to the anode side. However, it is basically also possible to electrically connect the driver circuit to an anode side of the light source. It may alternatively be advantageous if the driver circuit for each of its supply inputs is connected to its own driver supply line.

It can be advantageous for increasing the luminous intensity if each luminous module has several light sources per set, in particular light-emitting diodes with the same light spectrum, z. B. white or the same color LED, especially two green LEDs.

It is advantageous for the, in particular flexible, color adjustment and / or for increasing the luminous intensity if each luminous module has a plurality of sets of at least one light source and a driver circuit for supplying power to the at least one light source. These interconnected sentences correspond to the strands.

It is, in particular for the variable adjustment of a color emission, advantageous if at least three sets of at least one light source and an associated driver circuit are present (corresponding to at least three strands), wherein the light sources of at least two sentences or strands are each different in color.

FIG 1

zeigt ein Leuchtmodul in Explosionsansicht von schräg vorne;

FIG 2

zeigt das Leuchtmodul aus FIG 1 in Explosionsansicht von schräg hinten;

FIG 3

zeigt skizzenhaft eine Schaltung einer Leuchtkette mit mehreren Leuchtmodulen mit verteilter Treiberschaltung.

In the following, the lighting module will be described schematically with reference to an embodiment schematically.

FIG. 1

shows a light module in an exploded view obliquely from the front;

FIG. 2

shows the light module off FIG. 1 in an exploded view from diagonally behind;

FIG. 3

shows a sketch of a circuit of a light chain with several lighting modules with distributed driver circuit.

FIG. 1 and FIG. 2 each show a light module 1 from a chain of electrically connected lighting modules 1. In the embodiment shown, each module 1 / member of the chain with a plurality of LEDs 2,3,4 with each arranged in the emission direction scattering optics 5 and other electronic components (not shown) equipped board 6 on.

Front and back of the board 6 are a cover 7 and a heat sink. 8

Specifically, a red LED 2, a blue LED 3 opposite thereto, and two green LEDs 4 (only one of which are shown) adjacent thereto are used per module 1. As a result, the entire luminous area of the LEDs for green is selected to be larger than for red and blue (light area ratio green: red: blue = 2: 1: 1). This has an advantageous effect on the color mixture for white light, since the proportion of green is particularly high for a white mixture. As a result, relatively inexpensive LEDs 2,3,4 can be used, which also need not be driven to their power limits. Particularly suitable for this purpose is an activation of the LEDs 2, 3, 4 with a luminous component of green: blue: red of 60: 30: 10. Except white, by means of a suitable control of the LEDs 2, 3, 4 by means of pulse-width-modulated supply current, all others possible color mixtures are generated.

Along the chain, LEDs of the same color 2, 3, 4 are electrically connected in series (so-called "strands"), two separate series circuits (i.e., two strands) being used for the color green. The current per string is determined by means of a parallel connection of electronic components, eg. B. ICs and resistors (not shown), set, which convert the excess power, which may be different due to the production-related different forward voltages of the LEDs 2,3,4, in heat. These components are arranged on the modules 1 / boards 6 of the chain to distribute the heat evenly across the boards 6, resulting in more homogeneous operating conditions of the individual modules 1.

The electrical connection via a single or multi-pole electrical line, z. B. the ribbon cable 9 shown, or via individual lines, each formed for example as a strand or solid wire, which is connected to the board 6 becomes. To power another module (not shown), the power supply lines are looped through the board 6 and led to another cable connection, from which in turn leads a cable 9 to the other module. These two cables 9 or electrically connected cable connections are thus electrically connected to each other. However, only one power connection is sufficient for the power supply of the module 1.

The LEDs 2, 3, 4 can be equipped with or without patch scattering optics 5 and can be present in a packaged form (LED chip in a housing) or unhoused version (only the LED chip). In this embodiment, each of the LEDs 2, 3, 4 has a similar flat diffusing lens 5 with a wide radiation angle. This makes it possible with simple means a way to achieve comparatively uniform illumination at the same time wide viewing angles. In addition, the structure shown has only a small overall height in the region of the luminous elements 2, 3, 4, 5.

The illustrated circuit board 6 is a metal core board comprising a patterned copper layer on a dielectric 10, e.g. B. of polyimide or epoxy resin, and a substrate 11, z. As aluminum, copper or other metal. In this case, the heat generated on the circuit board 6 is discharged particularly effectively to the heat sink 8 via its large boundary surface.

The heat sink 8 is preferably made of a material of high thermal conductivity, such as. As aluminum. Alternatively, heat sinks 8 using copper, zinc and / or magnesium may also be used, or generally using highly conductive materials such as metals. The heat sink 8 is attached by means of a thermally conductive adhesive bond (electrically conductive or insulating) to the back of the board 6. In detail, the heat sink 8 has a rear side mounted on a plate 12 arrangement of regularly arranged pins 13 of the same height.

For attachment to a mounting surface, z. As shown here, the arrangement of the retaining tabs 14 in the middle of the long edges 8a and the longer side edges of the elongated heat sink 8 is particularly advantageous for two reasons: First, then the distance to the heat sources (LEDs, electrical / electronic components) low. This results in a particularly strong warming of the retaining tabs 14, which provides additional heat dissipation of the module 1 by heat conduction through the retaining tabs 14 to the mounting surface. Second, for free convection cooling on the heat sink 8, the long heatsink edges 8a of the air flowing through provide greater cross-sectional area (better cooling), and a negative influence of the retention tabs 14 is less pronounced than when provided at the shortest edges 8b of smaller cross-sectional area for the air. This leads to thermal properties of the heat sink 8, which depend less on the orientation of the heat sink 8 (eg vertically or horizontally) on a mounting surface than on differently arranged holding tabs 14.

The length of the pins 13 is chosen so that they protrude further back from the plate 12 than the retaining tabs 14 (height difference preferably from 0.05 to 0.3 mm). This ensures the contact of one or more pins 13 with the mounting surface and thus additional cooling by conduction over the bearing surfaces of the pins 13 on the mounting surface, which preferably consists of metal. The attachment of the heat sink 8 by means of the retaining tabs 14 is realized here by screws whose screw holes are shown in the retaining tabs 14 (without reference numerals).

For better heat dissipation, the heat sink 8 is surface treated, z. Example by means of a powder coating or anodization. This achieves a higher thermal emissivity than that of the raw material (better system heat dissipation by increased heat radiation). At the same time, the coating protects the heat sink from harmful environmental influences. A bright color with a high degree of light reflection of the coating is advantageous in order to increase the optical properties in the diffuse-reflecting light box.

The heat sink 8 has on the short sides 8b a recess 15 in the form of a bead. In combination with the lid 7, which has a bulge 16 at the appropriate location, a guide channel for the cable 9 is created. With a pulling force on the cable 9 in an arbitrary orientation (eg, up, down, right or left) carried by this channel, a transmission of force on solder joints of the cable 9 with the board 6 such that the force only in a small, insensitive as possible Angle range is directed to the board surface. This avoids shearing and peeling forces on the solder joints.

The lid 7 is made of thermally stable and UV-stable plastic. A bright color is advantageous, combined with a reflectivity of more than 60% in the visible range of the light to improve the optical properties of the module 1 in the lightbox. The cover 7 is shaped so that it partially conceals the heat sink 8 laterally and thus increases the overall reflectivity of the module 1. The lid 7 has recesses 17, which are formed so that the LEDs 2,3,4 can radiate their light unhindered in place and angle. The attachment of the lid 7 via a snap mechanism by means of plastic pins 18, which are guided through corresponding holes (without reference numerals) in the board 6,10,11 and in the heat sink 8 and engage. The cover 7 also has the property that it does not hermetically seal the underlying interior of the module 1, but lets moisture in and out. In this way, the accumulation of condensation is avoided.

For protection against condensation / corrosion and defective gases, the electrical contacts of the live parts on the board 6, 10 are coated with a layer of varnish. This reduces the risk of formation of creepage distances and clearances. In the embodiment shown, the paint for quality inspection has fluorescent properties. The viscosity of the paint is preferably selected so that it achieves complete wetting of the contacts via the effect of the capillary action. Advantageous are viscosities in the range of 100-500 mPas.

FIG. 3 shows a luminous chain 101, z. B. for backlighting of light panels, with n several successively interconnected lighting modules m1, m2, ..., mn. The lighting modules have the same basic design. Each of the lighting modules m1, m2,..., Mn has an exemplary light-emitting diode 102 and an LED driver circuit in the form of a current control circuit 103 for supplying power to the light-emitting diode (s) 102. The current control circuit 103 is electrically connected between two respective driver power supply lines 104, 105. One of these supply lines 105 corresponds to a continuous light source line 105, which is the LED 102 interposed. In the illustrated embodiment, the current control circuit 103 is electrically connected to one of its supply inputs to a cathode side of the associated LED 102. By tapping the required - in this case compared to the driver supply line 104 lower - voltage potential at the cathode of the respective light module m1, m2, ..., mn placed LED 102 is advantageously a connecting lines between the lighting modules m1, m2, ..., saved mn.

Driver outputs of the control circuit 103 are each electrically connected to a continuous light source supply line 106. On the light modules m1, m2,..., Mn-1, the driver outputs are not led to the LED 102, but are connected via the light source supply line 106. First on the last, so terminal light module mn the light source supply line ^ 106 is electrically connected to the light source line 105.

In other words, the partial currents of the individual, electrically parallel-connected control circuits 103 are all brought together at a node 107 on the terminal light module mn, and then the summation current is passed through the serially connected LEDs 102.

The light module mn, in which the light source supply line 106 is electrically connected to the light source line 105, can be derived, for example, from the basic shape of the other light modules m1, m2,..., By virtue of the fact that between basically open contacts 108 of the light source supply line 106 and the light source line 105 a bridge 109 is used.

Alternatively, all the lighting modules can correspond to the basic form with open contacts, wherein, for operation of the light chain, the free terminal of the light source supply line 106 of the terminal lighting module is electrically connected to the free terminal of the light source line 105. This variant has the advantage that the length of the light chain can be adapted flexibly and in the field and is essentially limited only by the maximum power consumption.

The illustrated luminous chain 101 has the advantage that, firstly, no separate module is required for driving the light-emitting diodes 102 and, secondly, due to the distribution of the driver components to the individual luminous modules m1, m2,..., Which are at least thermally, but usually also spatially separated. mn the occurring power loss, which is converted into heat, is also distributed to the individual lighting modules m1, m2, ..., mn. This leads to more homogeneous operating conditions of the individual LEDs 102. Occurring power losses due to fluctuations in the electrical Parameters of the LEDs 102 thus do not appear punctually in one place, which advantageously attenuates punctual heating and its influence on the optical parameters of the LEDs 102.

The illustrated electrical interconnection of LEDs 102 may also be referred to as a string. In other words, the arrangement shown corresponds to an LED string on the luminous chain 1 with a distributed driver circuit.

Of course, the present invention is not limited to the embodiment shown.

Alternatively, single-color LEDs can be used, for. B. also white glowing LEDs. The number and color of the LEDs on a module is not limited and may, for. B. also be one.

Furthermore, the retaining tabs need not be screwed, they can rather be attached as appropriate to the mounting surface. Thus, the heat sink may also be shaped so that it can be snapped or clipped into a preassembled guide rail on the mounting surface.

Also, the heat sink instead of by means of an adhesive bond z. B. by means of a screw or rivet and preferably another intermediate layer of thermally conductive and / or electrically insulating material (so-called. TIM material) to be connected to the board.

Alternatively, instead of metal core boards z. B. board materials such as FR4 or a so-called. FLEX film can be used.

In addition, the bulge of the lid can alternatively be chosen so that it exerts a force on the cable, which fixes or clamps the cable in the channel. Farther a fixation of the cable can be achieved without beading in the heat sink, for example, by holding-down device are formed in the lid, which press down the cable on the flat heat sink surface.

Also, the lid instead of plastic z. B. also made of metal and act as an additional heat sink element.

Also, non-fluorescent conformal coatings can be used. It may, in particular for use in interiors, also be dispensed with a protective coating.

Alternatively, the attachment of the lid can be realized by means of, for example, screws or rivets instead of the plastic pins.

A possible, non-limiting application of the light module or the chain consists in mounting on a rear wall (eg an aluminum plate) within a diffuse-scattered plexiglas box (so-called "light box") or within advertising letters for the area of the so-called Architectural Backlighting.

LIST OF REFERENCE NUMBERS

1

light module

2

red LED

3

blue LED

4

green LED

5

divergent lens

6

circuit board

7

cover

8th

heatsink

8a

long edge

8b

short edge

9

electric wire

10

dielectric

11

substratum

12

plate

13

pen

14

retaining tab

15

deepening

16

bulge

17

recess

18

Plastic pen

101

light chain

102

LED

103

control circuit

104

Driver supply line

105

Driver supply line / light source line

106

Light source supply line

107

Merge node point

108

Contact Power

109

bridge

m1-mn

light module

Claims (15)

Light module (1) for a light chain with at least one light source (2, 3, 4) and with at least one power connection (9) for supplying the at least one light source (2, 3, 4), wherein the light module (1) comprises: a heat sink (8); - At least one continuous light source line (105) having at least one intermediate light source (102), in particular at least one light emitting diode; - At least one continuous light source supply line (106); and - At least one continuous driver supply line (104,105) for operating at least one driver circuit (103) for controlling the at least one light source (102); - A driver circuit feeds at least one continuous driver supply line (104,105). Light module (1) according to claim 1, wherein the light sources (2,3,4) are arranged on a front side of a circuit board (6,10) and the heat sink (8) is connected to a rear side of the circuit board (6,11). Luminous module (1) according to claim 2, wherein the heat sink (8) by means of an adhesive to the board (6,11) is fixed and wherein the heat sink (8) by means of a mechanical connection element to the board (6,11) is attached , wherein between the heat sink (8) and the board (6) an intermediate layer of TIM material is arranged. Light module (1) according to one of the preceding claims, comprising as light sources a red light emitting diode (2), a blue light emitting diode (3) and two green light emitting diodes (4). Light module (1) according to one of the preceding claims, wherein the at least one light source comprises a white light source, in particular a white LED. Light module (1) according to one of the preceding claims, in which each light source (2,3,4) is associated with a scattering optics (5) for scattering the light emitted by the respective light source (2,3,4). Light module (1) according to one of the preceding claims, comprising at least two electrically interconnected power terminals for supplying the at least one light source (2,3,4). Light module (1) according to one of the preceding claims, comprising at least one control circuit for driving the at least one light source (2,3,4). A lighting module (1; m1-mn) according to any one of the preceding claims, wherein the drive circuit (103) is a current control circuit or a current constant circuit. Luminous chain (101) having at least two series-connected lighting modules (1; m1-mn) according to one of the preceding claims. A luminous chain (101) according to claim 10, wherein the lighting modules (1; m1-mn) are connected such that a set of light sources (2,3,4; 102) each comprising a light source (2,3,4; 102) the lighting modules (1, m1-mn), is electrically connected in series. A luminous chain (101) according to claim 11, wherein said lighting modules (1; m1-mn) are connected to comprise a set of same-color light sources (2,3,4; 102) respectively a light source (2, 3, 4; 102) of the lighting modules (1; m1-mn) is electrically connected in series. A luminous chain (101) according to any one of claims 10 to 12, wherein the lighting modules (1; m1-mn) are connected so that a power loss of a drive circuit (103) for the light sources (2,3,4; 102) is substantially evenly distributed on the light modules (1; m1-mn). A light chain (101) according to any one of claims 10 to 13, wherein drive circuits (103) for the light sources (2,3,4; 102) are electrically connected in parallel. A luminous chain (101) according to any one of claims 10 to 14, wherein - At least two of the lighting modules (m1-mn) at least one set of at least one light source (102) and a driver circuit (103) for controlling the at least one light source (102) and - The driver circuits (103) of a set of the respective lighting modules (m1-mn) are electrically connected in parallel with each other and - The light sources (102) of this one set of the respective lighting modules (m1-mn) are electrically connected to each other in series and - The driver outputs of the driver circuits (103) at a node (107) for the common power supply of all the light sources (102) of this one set are merged.

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