DE102011087658A1 - Parallel connected light chains - Google Patents

Abstract

It is proposed a circuit arrangement with at least two parallel-connected luminous chains, with each luminous chain, a regulator is connected in series, wherein a current of a working as a power source energy supply is distributed to the luminescent chains, that at least that regulator in the branch with the highest voltage drop the luminous chain has the highest gain or is operable in a saturated mode of operation. It is advantageous that the light chains can each be operated stably with the power provided for them. Also, a method for operating the light chains and a light module with at least one such circuit arrangement are proposed.

Description

The invention relates to a circuit arrangement with light chains connected in parallel, each light chain in particular having at least two Halbleiterleuchtelemente, and a method for controlling the light chains and a light emitting module with at least one such circuit arrangement.

It is known to operate light-emitting diodes (LEDs) individually or in LED chains in parallel to an electrical power supply. Differences in the forward voltage (forward voltage) of the LEDs can be compensated by series resistances. As a result, the current is partially balanced by the LEDs.

It is disadvantageous that even LEDs of the same type often differ in their physical parameters and the resulting losses in the series resistors in the parallel current paths are different. This results in an undesirable asymmetry of the current in the parallel-connected LEDs or LED chains.

The different forward voltages of the LEDs are often production-related. It is now possible to sort the light-emitting diodes according to their forward voltages (also referred to as "binning" or "forward voltage binning"), and to use only those light-emitting diodes which have the same or comparable forward voltages. However, this approach is complex and involves high costs.

No less expensive, but increasing the yield of usable single LED is the approach of grouping. In this case, the forward voltage of an entire LED chain is considered. Individual light-emitting diodes with slightly different forward voltage are distributed to the LED chains in such a way that a uniform total forward voltage results.

Also, the forward voltage of a light emitting diode is temperature dependent. Since different temperature dependencies can exist between individual light-emitting diodes, as a result an asymmetry between the parallel-connected light-emitting diodes or LED chains increases.

The object of the invention is to avoid the above-mentioned disadvantages and, in particular, to provide a cost-effective and efficient solution for the operation of parallel-connected semiconductor light-emitting elements.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

• – mit mindestens zwei parallel geschalteten Leuchtketten,
• – wobei mit jeder Leuchtkette ein Regler in Reihe geschaltet ist,
• – wobei ein Strom einer als Stromquelle arbeitenden Energieversorgung derart auf die Leuchtketten verteilbar ist, dass mindestens derjenige Regler in dem Zweig mit dem höchsten Spannungsabfall an der Leuchtkette die höchste Verstärkung aufweist oder in einem gesättigten Betriebsmodus betreibbar ist.

To solve the problem, a circuit arrangement is proposed

• With at least two light chains connected in parallel,
• - with each light chain a regulator is connected in series,
• - Wherein a current of a working as a power source power supply is distributed to the light chains such that at least one controller in the branch with the highest voltage drop on the light chain has the highest gain or is operable in a saturated mode of operation.

In a special case (for example, symmetry of the LED strings, all forward voltages of the LEDs are the same), all regulators are turned on. This corresponds to a saturated operating mode.

In particular, one of the light-emitting elements or light-emitting diodes of the light chain different series impedance can be provided per light chain, wherein at least this series impedance of those light chain with, for example, the highest forward voltage assumes its smallest possible value. In this respect, the regulator mentioned above can be such a series impedance. For example, the series impedance may be a controllable series impedance.

A further development is that the remaining controllers can be operated in a linear or quasi-linear operating mode.

Another development is that a light chain comprises a series connection of at least two semiconductor light elements, in particular light-emitting diodes.

In particular, it is a development that the controller comprises at least one mosfet or an operational amplifier.

It is also a development that the controller comprises at least one transistor.

In particular, a bipolar transistor, e.g. a npn or pnp transistor can be used as a regulator or as part of the regulator.

• – der Regler einen Transistor, insbesondere einen npn-Transistor, umfasst,
• – dessen Kollektor-Emitter-Strecke zusammen mit einem Emitter-Widerstand mit der Leuchtkette in Reihe geschaltet ist und
• – dessen Basis-Anschluss mit den Basis-Anschlüssen der anderen Regler und mit einer weiteren Stromquelle verbunden ist.

Furthermore, it is a training that

• The regulator comprises a transistor, in particular an NPN transistor,
• - Whose collector-emitter path is connected in series with an emitter resistor with the light chain in series and
• - Its base terminal is connected to the base terminals of the other controllers and to another power source.

In this way, the base terminals of the transistors are supplied by the further current source whose current is greater than a maximum nominal current through the parallel connection of all the light chains divided by a minimum current gain of the transistors.

• – dass der Regler einen Transistor, insbesondere einen npn-Transistor, umfasst, – dessen Kollektor-Emitter-Strecke zusammen mit einem Emitter-Widerstand mit der Leuchtkette in Reihe geschaltet ist, – dessen Basis-Anschluss mit den Basis-Anschlüssen der anderen Regler verbunden ist,
• – dass eine weitere Stromquelle vorgesehen ist, die jeweils über eine Diode mit dem Kollektor des Transistors (insbesondere jedes der Transistoren) verbunden ist, wobei die Kathode der Diode in eine solche Richtung, dass ein Teil des Stromes von der weiteren Stromquelle anstatt durch die Basis des Transistors durch dessen Kollektor fließen kann;
• – wobei die weitere Stromquelle direkt, über eine Diode oder über einen Widerstand mit dem Basis-Anschluss des Transistors (insbesondere mit den Basisanschlüssen der mehreren Transistoren) verbunden ist.

A next development is

• - That the controller comprises a transistor, in particular an NPN transistor, - whose collector-emitter path is connected together with an emitter resistor to the light chain in series, - whose base terminal connected to the base terminals of the other controller is
• - That a further current source is provided, which is connected in each case via a diode to the collector of the transistor (in particular each of the transistors), wherein the cathode of the diode in such a direction that a portion of the current from the further power source instead of through the base of the transistor can flow through its collector;
• - Wherein the further current source is connected directly, via a diode or via a resistor to the base terminal of the transistor (in particular to the base terminals of the plurality of transistors).

It is advantageous that the transistor of the respective regulator can be operated unsaturated or linear and has substantially the same base-emitter voltage as the transistors of the other controller (with appropriate design). The current distribution between the current paths is symmetrical or predetermined within the setting.

The collector-emitter voltage of the transistor is preferably close to saturation in order to be able to operate all the regulators for all luminous chains in the linear range. The collector-emitter voltage of the transistor is preferably less than its base-emitter voltage to minimize losses within the lighting module comprising the parallel connection of the light chains, their associated regulators and the associated emitter resistors.

• – dessen Kollektor-Emitter-Strecke zusammen mit einem Emitter-Widerstand mit der Leuchtkette in Reihe geschaltet ist und
• – dessen Basis-Anschluss mit den Basis-Anschlüssen der anderen Regler und über einen Widerstand mit einem Spannungsabgriff innerhalb der Leuchtkette verbunden ist.

An embodiment is that the regulator comprises a transistor (eg an npn transistor),

• - Whose collector-emitter path is connected in series with an emitter resistor with the light chain in series and
• - Its base terminal is connected to the base terminals of the other controller and a resistor to a voltage tap within the light chain.

The voltage tap within the light chain is, for example, a node within the series-connected semiconductor light elements, e.g. between two of the series-connected semiconductor light-emitting elements.

In particular, only one controller can have such a connection with a voltage tap within the luminous chain. In addition, it is an option that a plurality of regulators of the circuit arrangement (in particular all regulators) are connected via a resistor to a voltage tap within the respective luminous chain.

In particular, a circuit system is proposed comprising at least two circuit arrangements as described herein, in which the base terminals of the regulators are connected to each other between at least two of the circuit arrangements.

It should be noted that the base terminals of several controllers, which may be arranged in different light modules, may be connected. For example, the adjustment of the current in the current branches, in particular the symmetrization of the current, can thus be achieved via a plurality of lighting modules.

The connection between the modules, for example, by means of a common cable guide or a ribbon cable done to reduce the sensitivity to interference.

An alternative embodiment consists in that at least two semiconductor luminescent elements of different luminescent chains are arranged in a locally or optically grouped manner.

In particular, a plurality of LEDs can thus be arranged stacked. The grouping allows LEDs of different types to be used for light mixing.

For example, a current distribution and thus color location calibration of the LEDs can be achieved by adjusting or calibrating the emitter resistors of the regulator (transistor) responsible for the respective LED chain.

A next embodiment is that the current to the light chains by means of at least one pulse width modulation circuit can be distributed.

• – zwischen dem Kollektor und der Leuchtkette;
• – vor der Basis der Transistors;
• – nach dem Emitter des Transistors.

If the regulator for the light chain comprises an (eg npn) transistor, then an electronic switch, which can be controlled via a pulse width modulation controller, can be arranged at at least one of the following positions:

• Between the collector and the light chain;
• In front of the base of the transistor;
• - After the emitter of the transistor.

It should be noted that the comments on the npn transistor are basically also applicable for a pnp transistor or in a correspondingly adapted wiring for a Mosfet in corresponding for the expert known dual wiring.

The electronic switch, which can be controlled via the pulse width modulation control, can be, for example, a transistor or a mosfet.

It is also an embodiment that by means of the pulse width modulation circuit at a time a predetermined number of light chains is de-energized.

For example, a fixed number of current paths (and thus, for example, LED chains) may be de-energized and another number of current paths may be on.

A development is that in case of failure, the controller for the affected light chain can be deactivated. This deactivation function of the controller can be taken over, for example, by the pulse width modulation circuit described above.

An additional embodiment is that the error case includes an interruption in the luminous chain.

Short circuits of individual light-emitting diodes in the light chains can be compensated, for example, by the regulators during normal operation of the circuit arrangement.

For example, when using a transistor, in particular a npn transistor, as a regulator, the base of the transistor can be separated from the common base potential, if a fault occurs (LED chain interrupted) occurs in the LED chain associated with the transistor. This has the advantage that in case of failure of a single LED not all LEDs of the module fail.

A further refinement is that the controller can be deactivated via a mosfet, wherein the mosfet can be activated via a voltage tap within the luminous chain.

Another embodiment is that the controller may not be deactivated, but continues to operate in normal operation, if the error occurs in parallel to said voltage tap in the LED chain considered.

According to a further embodiment, a power requirement of the circuit arrangement can be signaled.

In particular, the circuit arrangement for signaling the power requirement may have a characteristic resistor.

The above-mentioned object is also achieved by means of a circuit system, in particular comprising at least one lighting module, wherein the circuit system comprises at least one of the circuit arrangements described here, wherein a power requirement of the circuit arrangement can be signaled.

For example, the power requirement of the light module can be signaled to the power supply. In this case, a plurality of such lighting modules can be connected in parallel and have means which enable the power supply to determine which power requirement each of the lighting modules has. Thus, the signaling means may be designed such that the sum of the power required for all lighting modules is reported to the power supply.

A further development is that the lighting module has an identification resistor which is arranged between a reference potential and a measuring input, wherein the measuring input can be connected to the power supply.

The measuring input can be a measuring input of the lighting module, which can be connected via a measuring output to a measuring source (current or voltage source), e.g. included in the power supply. Based on the detectable by means of the measurement input electrical variable (current or voltage), the power supply can infer the power demand of the at least one light module connected to it.

• – bei dem die Kennwiderstände der Schaltungsanordnungen parallel geschaltet sind,
• – bei dem die Kennwiderstände der Schaltungsanordnungen zwischen einem Bezugspotential und einem Messeingang angeordnet sind,
• – wobei der Messeingang mit der Energieversorgung verbindbar ist,
• – wobei zwischen dem Messeingang und dem Bezugspotenzial eine Messspannung anlegbar ist,
• – wobei der Strom durch den Messeingang messbar ist und
• – wobei von der Energieversorgung deren Quellenstrom proportional zum dem an dem Messeingang gemessenen Strom einstellbar, insbesondere regelbar, ist.

Also proposed is a circuit system comprising at least two of the circuit arrangements described here,

• In which the characteristic resistances of the circuit arrangements are connected in parallel,
• In which the characteristic resistances of the circuit arrangements are arranged between a reference potential and a measuring input,
• - wherein the measuring input is connectable to the power supply,
• Wherein a measuring voltage can be applied between the measuring input and the reference potential,
• - Where the current through the measuring input is measurable and
• - Wherein the source supply current is proportional to the current measured at the measuring input adjustable, in particular controllable, from the power supply.

A refinement is that the characteristic resistors present per light module and characterizing the specific power requirements of their respective module are connected in parallel between several modules via their measuring inputs and via the reference potential and connected to the measuring output of the power supply.

By way of example, a constant voltage source provided in the power supply for precisely these measuring purposes can be connected to the measuring output, the current measured at the measuring output and, correspondingly, a current for supplying the at least one lighting module proportional (corresponding) to the current measured at the measuring output.

An embodiment is that a relation of the emitter resistor and the characteristic resistor for a circuit arrangement for the (in particular for all) circuit arrangements of the circuit system is the same.

A further refinement is that said reference potential is identical to the common return current common to all lighting modules connected to one and the same power supply.

• – bei dem die Kennwiderstände der einzelnen Schaltungsanordnungen in Serie geschaltet sind,
• – bei dem die Kennwiderstände zwischen einem Bezugspotential und einem Messeingang angeordnet sind,
• – wobei der Messeingang mit der Energieversorgung verbindbar ist,
• – wobei an dem Messeingang ein Messstrom bereitstellbar ist,
• – wobei die Spannung zwischen dem Messeingang und dem Bezugspotenzial messbar ist und
• – wobei von der Energieversorgung deren Quellenstrom proportional zu der zwischen dem Messeingang und dem Bezugspotenzial gemessenen Spannung einstellbar, insbesondere regelbar, ist.

Furthermore, a circuit system is proposed comprising at least two of the circuit arrangements described here,

• In which the characteristic resistances of the individual circuit arrangements are connected in series,
• In which the identification resistors are arranged between a reference potential and a measuring input,
• - wherein the measuring input is connectable to the power supply,
• - Wherein a measuring current is available at the measuring input,
• - where the voltage between the measuring input and the reference potential is measurable and
• - Whose source power is proportional to the voltage measured between the measuring input and the reference potential adjustable, in particular controllable from the power supply.

Another embodiment is that a signaling means of a lighting module has two externally accessible measuring inputs, which are connected to none of the previously described potentials inside the lighting module.

A further development is that this potential-free signaling means is a characteristic resistor characterizing the power requirement of the lighting module.

A further refinement is that the characteristic resistances of all lighting modules operated in parallel on one and the same power supply are connected in series via their respective two measuring inputs. In this case, the open measuring input of the lighting module, which is preferably furthest away from the power supply, can be connected to the power return line for supplying energy.

In this case, the measuring source included in the power supply may be a current source which outputs at its measuring output a certain current to the first measuring input, preferably of the module which is closest to the power supply. Based on the voltage measurable at the said measuring output, the power supply adjusts its output current, which it delivers to all connected lighting modules.

A further development is that a product of the emitter resistor and the characteristic resistor for the same circuit arrangement for the (in particular for all) circuit arrangements of the circuit system is the same.

An additional embodiment consists in that an offset element is inserted at one point of the series connection of the signaling elements formed over the respective two measuring inputs, instead of a direct electrical connection. This is particularly advantageous because when powering a series circuit of signaling elements and measuring the resulting voltage at the measuring output, if necessary, no "clean zero" corresponding to a zero-current case can be measured. In order to deal with this case appropriately, the power supply preferably outputs its minimum output current only when the measuring voltage is greater than a certain offset voltage. This offset voltage can be predetermined by means of a Zener diode as an offset element, the Zener voltage corresponding to the offset voltage. Thus, the offset member in current flow, a constant counter voltage independent of the provide actual level of the measuring current. Preferably, the offset element is selected as the termination of the series-connected measurement. It is also an option that the offset element between the measuring output and the first measuring input of that circuit arrangement is integrated, which is the power supply closest. In another exemplary embodiment, the offset element is integrated into the voltage measurement included in the power supply at the measurement output such that the required offset voltage is automatically subtracted from the measured voltage value before the measured value is further processed.

Accordingly, the measuring source can have a corresponding processing unit for evaluating the measured or signaled power requirement of at least one of the lighting modules. For example, the lighting modules can be controlled by the processing unit in a time-division multiplex method, so as to determine the respective power requirement per lighting module. Other forms of addressing of the lighting modules are possible. In particular, the power requirement at predetermined times (regular or irregular) can be measured by such a processing unit (in the measurement source). It should be noted that "signalable" is to be understood as meaning that the measuring source can determine the power requirement, be it by measuring a momentary current or a current voltage or by transmitting information that can be inferred from the power requirement.

• – wobei mit jeder Leuchtkette ein Regler in Reihe geschaltet ist,
• – bei dem ein Strom einer als Stromquelle arbeitenden Energieversorgung derart auf die Leuchtketten verteilt wird, dass mindestens derjenige Regler in dem Zweig mit dem höchsten Spannungsabfall an der Leuchtkette die höchste Verstärkung aufweist oder in einem gesättigten Betriebsmodus betreibbar ist.

The above-mentioned object is also achieved by a method for controlling a plurality of parallel-connected luminous chains,

• - with each light chain a regulator is connected in series,
• - In which a current of a working as a power source power supply is distributed to the light chains such that at least one controller in the branch with the highest voltage drop on the light chain has the highest gain or is operable in a saturated mode of operation.

The features of the device (circuitry) are applicable to the method accordingly.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

Show it:

1 a schematic circuit diagram for a loss-minimized current balancing, wherein a power source operating power supply a current for parallel-connected LED chains, and each of the LED chains comprises a series circuit of LEDs with a certain forward voltage, and wherein a further current source drives the current balancing circuit;

2 an alternative circuit based on the circuit of 1 in which the current balancing circuit is extended by a control current limiting circuit;

3 an alternative implementation of in 1 shown circuit, in particular the local other power source, as an efficient and cost-effective control for a loss-minimized current balancing;

4 an extension of in 3 shown circuit by means of a uniform configuration of the replacement of the other power source;

5 a circuit diagram with a parallel connection of several (light) modules, wherein in addition to the two poles for the common power supply additionally interconnected within the individual modules base terminals of the regulator transistors are connected;

6A an exemplary circuit arrangement based on the representation of 5 , wherein each module has a measuring input, which is connectable to a characteristic resistor of the module, wherein the measuring inputs of all modules involved in this circuit are connected to each other via a further connecting line, whereby the characteristic resistors of all participating modules are connected in parallel, and wherein this connecting line with a Measuring output of the power supply is connectable;

6B another exemplary circuit arrangement based on the representation of 5 , wherein each module has two measuring inputs, which are connected to any other electrical potential within its module, which may be connected by a characteristic resistor of the module, wherein by means of these two measuring inputs and by means of another section-wise connecting line, the characteristic resistances of all participating in this circuit modules in Series are connected, wherein the second measuring input of the energy supply preferably the furthest remote module is coupled to the power return line for power supply, and wherein the first measuring input of the power supply preferably closest to the module with a measuring output of the power supply is connectable;

7 a circuit arrangement based on 1 , wherein in addition to the emitter resistors adjustable resistances are provided;

8th a schematic diagram based on 1 , wherein the controller is shown by way of example with a plurality of electronic switches, which are controllable in the context of a pulse width modulation;

nine a schematic diagram illustrating how the transistor can be separated from the common base potential by means of a Mosfets, and as by means of a Zener diode, substantially parallel to the control tap for the Mosfet, the supersaturation of the transistor in case of interruption of the chain below the control tap for the mosfet can be avoided.

The solution presented enables an efficient and cost-effective operation of parallel-connected semiconductor light-emitting elements, e.g. Light-emitting diodes (LEDs) or LED chains.

Thus, a circuit may be provided which has a plurality of LED chains connected in parallel with each LED chain comprising a plurality of LEDs connected in series. The anodes of the LEDs connected in series point in the direction of the positive pole of the supply voltage and the cathodes of the series-connected LEDs point in the direction of the negative pole of the supply voltage.

For example, a maximum voltage is given for a string of LEDs, e.g. a SELV limit (SELV: safety extra low voltage). The current through the LEDs or LED chains may e.g. be determined by the type of LEDs used. Thus, LEDs of different types may each be arranged in LED strings (i.e., one type per LED string), with a particular current being adjustable for each LED string.

This approach allows flexible supply of multiple LED strings or LED modules (each including, for example, at least one LED string) to a common power supply that can operate as a source of power or voltage.

In particular, it is possible that the current between the LED chains is set flexibly. For example, the color of several LEDs (LED chains) can be optically mixed.

Unwanted color dispersion may be reduced by preselecting certain LEDs (sufficiently similar LEDs, e.g., by binning pre-selected LEDs) and / or by calibrating the power distribution between LED strings.

It should be noted that in the context of the solution proposed here, the "symmetrization" as the symmetrical distribution of the current into a plurality of current paths is only an exemplary solution for adjusting the current in a plurality of parallel current paths. Rather, the current in each current path may be different, e.g. by different LED types. Preferably, the solution presented here is used to adjust the current in the current paths comprising the semiconductor light elements so that it corresponds to a desired value and is largely maintained at this value. In other words, the current in the current paths is adjusted so that a steady state is maintained. The symmetrization mentioned below thus applies by way of example; Accordingly, with the measures presented, an unsymmetrical but desired setting (stationary setting according to a specification) of the current in the current paths can be achieved. The term (current) symmetrization (circuit) thus includes as an illustrative example all types of corresponding Stromeinstellschaltungen. The latter are also addressed when (current) symmetrization (-sschaltung) is mentioned.

It is proposed to distribute the power of a working as a power source power supply to multiple LED chains. In this case, a symmetrization of the current between the LED chains (or a targeted adjustment of the distribution of the current between the LED chains) is achieved at different forward voltages of the LED chains by a transistor is connected in series with each LED chain, the ensures equalization of different voltages in each branch. Thus, that transistor is fully turned on (saturated), which is connected to the LED chain, which has the highest forward voltage.

The other transistors (for the other LED strings) equalize the voltage difference by operating in their linear range.

The power loss is small when the difference between the forward voltages is small, and when there is as little as possible voltage difference between the collectors and emitters of all the transistors involved. This is achieved as soon as at least one of the participating transistors is operated saturated. In the ideal case (symmetry of the LED chains, all forward voltages of the LEDs are the same) all transistors are switched through (saturated operation).

If the forward voltages of the LEDs are different (which in reality will be the norm), the voltage drop in the balancing circuit is determined by the difference between the highest forward voltage (Vfmax) and the forward voltage of the respective LED string x (Vfx). It is thus appropriate to optimize over a fixed voltage in a converging linear regulator.

The drive can be achieved inexpensively by operating the transistors with current feedback via an emitter resistor associated with each transistor and by having the bases of the transistors at a common potential represented by a base bus. The base current rail is supplied by a further current source whose current is greater than a maximum LED module target current I _{in_max} divided by a minimum current gain of the transistors ß _min.

1 shows a schematic circuit diagram for a loss minimized current balancing. One as a power source 101 working power supply provides a current I _in parallel to LED strings 102 . 103 and 104 ready. Each of the LED chains 102 to 104 comprises a series connection of LEDs. The LED chain 102 has a forward voltage Vf1, the LED chain 103 has a forward voltage Vf2 and the LED chain 103 has a forward voltage Vfn.

The LED chain 102 is with the collector of an npn transistor 105 connected. The emitter of the transistor 105 is about a resistance 108 with a knot 111 connected, the current return of the three involved here LED chains 102 to 104 represents and with the power source 101 connected is. The LED chain 103 is with the collector of an npn transistor 106 connected. The emitter of the transistor 106 is about a resistance 109 with a knot 111 connected. The LED chain 104 is with the collector of an npn transistor 107 connected. The emitter of the transistor 107 is about a resistance 110 with a knot 111 connected. The resistors 108 to 110 are also referred to as "emitter resistors".

Another power source 112 represents a current I _B for driving the base terminals of the transistors 105 to 107 ready, whose common node is a base busbar 307 forms. The other pole of the power source 112 is with the node 111 connected.

An exemplary and advantageous interpretation of in 1 shown circuit is: I _B ≥ I _{in_max} / β _min ; I _B << I _in .

Optionally, the base current in the branch with the LED string having the largest forward voltage may be through an alternative current branch for the current source 112 , which does not lead via the base busbar, to be limited. The alternative current branch is preferably controlled such that at least one current branch receives a collector voltage below a certain limit.

An inexpensive implementation of the alternative current branch can be achieved by means of star-connected diodes whose cathodes lead to the collectors of the transistors of each branch of current.

2 shows an alternative circuit based on the circuit of 1 ,

In contrast to 1 is the power source 112 via a resistor R _L via the adjoining base busbar 307 with the base terminals of the transistors 105 to 107 connected.

A knot 113 indicates the connection between the resistor R _L and the power source 112 , The knot 113 is via a diode D _L1 with a node 114 connected, the node 114 the connection between the LED chain 102 and the collector of the transistor 105 designated. The knot 113 is via a diode D _L2 with a node 115 connected, the node 115 the connection between the LED chain 103 and the collector of the transistor 106 designated. The knot 113 is via a diode D _L3 with a node 116 connected, the node 116 the connection between the LED chain 104 and the collector of the transistor 107 designated. The diodes D _L1 , D _L2 and D _L3 each point with their cathode in the direction of the nodes 114 . 115 and 116 it is thus the above-mentioned star-shaped diode circuit.

The resistor R _L can be used if the forward voltage of the diodes is greater than the maximum base-collector voltage desired for the linear operation case near saturation of the transistor connected in series with the highest flux-carrying LED string. This is usually not the case when the diodes D _L1 , D _L2 and D _{L3 are designed} as Schottky diodes. Then resistance R _{L is} usually superfluous and can be replaced by a short circuit (not shown). A base-collector voltage close to zero is achieved when a fourth diode D _B with anode identical to the diodes D _L1 to D _L3 in the direction of the current source 112 is used instead of the resistor R _L (not shown).

Another embodiment is that the base busbar 307 as in 1 directly with the other power source 112 is connected thereto and the base of each transistor involved is connected via an individual base resistor R _Lx and the collector of each transistor involved via the associated diode D _{Lx is connected} in an already known manner.

It is advantageous that the transistors 105 to 107 can be operated unsaturated or linear and have a substantially same base-emitter voltage U _BE . The current distribution between the current paths is symmetrical or within the given setting, for example by different values of the emitter resistors 108 . 109 . 110 ,

U_BE

die Basis-Emitter-Spannung,

U_RL

die Spannung, die an dem Widerstand R_L abfällt,

U_DLx

die Spannung an der Diode D_L1, D_L2 oder D_L3,

U_{CE_Sättigung}

die Kollektor-Emitter-Spannung in Sättigung,

Vf_x

die Vorwärtsspannung der LED-Kette x

bezeichnen.An exemplary and advantageous interpretation of in 2 shown circuit is: U _BE + U _RL - U _DLx > U _{CE_saturation;} U _BE + U _RL - U _DLx << Vf _x ; in which

U _BE

the base-emitter voltage,

U _RL

the voltage dropping across the resistor R _L

U _DLx

the voltage at the diode D _L1 , D _L2 or D _L3 ,

U _{CE_saturation}

saturating the collector-emitter voltage,

Vf _x

the forward voltage of the LED chain x

describe.

The minimum collector-emitter voltage U _CE corresponds to the sum of the base-emitter voltage U _BE plus the voltage U _RL at the resistor R _L minus the _forward voltage U _{DLx of} the diode D _{Lx of} that branch 102 . 103 or 104 with the greatest forward voltage. The collector-emitter voltage U _CE as now leading variable for the actual control voltage U _BE is thus effectively limited in order to achieve the desired effect, ie that all transistors are operated in the linear range.

3 shows an alternative implementation of in 1 shown circuit as an efficient and cost-effective control for a loss-minimized current balancing.

Based on the in 1 shown are the base terminals of the transistors 105 to 107 in 3 about a resistance 301 driven, with a knot 302 is connected and the base busbar 307 powered. The knot 302 is a connection between two LEDs of the LED chain 104 , In the 1 shown further power source 112 is through the resistance 301 formed and eliminated in 3 ,

The knot 302 thus corresponds to a voltage tap within the LED chain 104 , which is used to drive the base terminals of the transistors 105 to 107 is being used.

An asymmetry caused by the (base) resistance 301 is caused and cause a slightly larger current in the LED chain 104 above the node 302 can lead, by adjusting the resistance 110 be at least partially offset. This can be the resistance 110 preferably larger dimensions than the resistors 108 and 109 ,

4 shows an extension of in 3 represented circuit by means of a loss-minimized current negative feedback, in which the base terminals of the transistors 105 to 107 through the base busbar 307 connected to each other. As in 3 is the resistance 301 with the base busbar 307 connected. Furthermore, there is a resistance 303 provided on the one hand with a node 304 inside the LED chain 103 and on the other hand with the base bus bar 307 connected is. Also is a resistance 305 provided on the one hand with a node 306 inside the LED chain 102 and on the other hand with the base bus bar 307 connected is.

An asymmetry, that of the resistance 301 according to 3 is at least partially compensated by a resistance 301 . 303 and 305 for each of the LED chains 102 to 104 is provided.

In addition, it should be noted that the details of 2 who are facing a supplement 1 represent accordingly to the 3 and / or the 4 can be applied. The description of the further current source by at least one resistor described in these two figures, conversely, remains unaffected in their function.

Since the properties of type-like LED lighting modules are currently changing per generation, and on the other hand, a light installation including the aforementioned power supply has a very high life expectancy, it should be possible to incorporate newer modules with different properties in an existing lighting system, without As a result, the illumination result changes (significantly). In particular, newer modules are more efficient than their predecessors, thereby existing LED lighting systems with a given power supply can be extended or upgraded in principle, thanks to the lower energy requirement of the newer individual LED modules.

A prerequisite for such modularity and extensibility is already given by the present on all modules per LED chain emitter series resistors. The higher the impedance of such a resistor, the lower the rated current of the LED chain connected in series via the regulator. The complete function of these resistors across a plurality of LED modules, that is to say over an entire lighting system, is preferably achieved when said basic busbars are connected to one another as a second condition.

5 shows a circuit diagram with a parallel connection of several modules 501 and 502 ,

The module 501 as well as the module 502 can according to the in 4 be constructed circuit shown. For example, the modules have 501 and 502 LED chains with the same or similar forward voltages. To minimize the losses in a whole such arrangement, mainly in the regulators, here the npn transistors 105 to 107 arise, it is particularly advantageous if all the modules involved 501 . 502 have the same nominal operating voltage.

A current asymmetry between such parallel connected modules 501 . 502 can be effectively avoided by the base busbars 307 between the modules 501 . 502 over a cable 503 get connected.

It is possible that the modules 501 . 502 an external B field 504 are exposed.

One through the magnetic alternating field 504 Induced susceptibility of the modules 501 . 502 can be reduced by reducing or minimizing the trapped area between the common base potential and the return current line. This can be achieved, for example, by means of a common cable guide or by means of a ribbon cable.

Optionally, a power demand of modules connected in parallel can be transmitted, eg signaled. This can be achieved for example by means of so-called characteristic resistors R _setx .

6A FIG. 12 shows exemplary circuitry based on the illustration of FIG 5 , where the as a power source 101 working energy supply (not in 6A represented) a measuring input U _Set 601 having. A characteristic resistor R _set1 is here on the module 501 arranged, wherein the characteristic resistor R _set1 on the one hand to the measuring input 601 and on the other hand at a ground potential (eg the node 111 ) connected. A characteristic resistor R _set2 is on the module 502 arranged, wherein the characteristic resistor R _set2 on the one hand at the measuring input 601 and on the other hand at a ground potential (eg the node 111 ) connected.

By the characteristic resistors R _set1 and R _set2 , the power demand of the parallel connected modules 501 and 502 be determined.

In particular, it is an option that the characteristic resistors are connected in parallel so that the conductivity is proportional to the desired current. In the case of two modules and the arrangement according to 6A the conductivity is too 1 / (R _set1 + R _set2 ).

One possible realization is that at the measuring entrance 601 a constant voltage source U _{set is} connected, the current at the measuring input 601 is measured and the current I _in proportional (corresponding) to the measured current at the measuring input 601 is regulated.

Another option is that the emitter resistors 108 to 110 be dimensioned so that distribute the currents between the modules analogous to the characteristic resistors R _setx .

In particular, the resistors can be dimensioned as follows: R _E501 / R _set1 = R _E502 / R _set2 = R _E50x / R _setx

R _E501 denotes the resistance of the resistors 108 . 109 and 110 on module 501 , and R _E502 denotes the resistance value of the resistors 108 . 109 and 110 on module 502 ,

6B shows another exemplary circuit arrangement, wherein each module 501 . 502 and 505 two measuring inputs 551 . 561 . 552 . 562 and 555 . 565 in particular having no other electrical potential within its associated module 501 . 502 . 505 are connected. These measuring inputs are characterized by a characteristic resistor R _set1s , R _set2s , R _{set3s of} the respective module 501 . 502 and 505 connected to each other, wherein by means of these two measuring inputs and by means of another section-wise connecting line 507 . 508 the characteristic resistances of the modules 501 . 502 . 505 are connected in series. The fair entrance 565 of the power supply preferably farthest module 505 is with the power return 111 coupled to the energy supply. The first measuring input 551 of the power supply preferably closest to the module 501 is with a measuring output I _set 509 connected to the energy supply.

This results in that the sum of the series resistances is proportional to the module connected for all 501 . 502 . 505 total desired current of the working as a power source power supply.

One possible realization is that to the measuring output 509 a constant current source I _{set is} connected, the voltage at the measuring output 509 is measured and the current I _in proportional (corresponding) to the measured voltage at the measuring output 509 is regulated.

An alternative is that the emitter resistor groups R _E501 , R _E502 , R _E503 be dimensioned so that the currents between the modules in analogy to the series-connected characteristic resistors R _set1s , R _set2s , R _set3s , R _setns distribute.

In particular, the resistors can be dimensioned as follows: R _E501 * R _set1s = R _E502 * R _set2s = R _E503 * R _set3s = R _E50n * R _setns

As stated above, by appropriate selection of the values for the resistors 108 . 109 . 110 also within a module different currents for the individual LED chains are set. Since there is equal voltage across the emitter resistors via the base busbar and because of the good approximation across all LED strings uniform base voltage, the relation that the current in a considered LED chain is the higher, the lower the associated emitter resistance , In a first step, the emitter resistor values are varied, for example, by exchanging the components or by connecting adjustable resistors in parallel. Another possibility is to replace the usually fixed emitter resistors by adjustable within certain limits resistors. The replacement of the fixed resistors or the operation of the adjustable resistors to achieve such variations can be done before or during startup.

7 shows a circuit arrangement based on the representation of 1 ,

In contrast to 1 is parallel to the resistor 108 an adjustable resistor 701 , parallel to the resistor 109 an adjustable resistor 702 and parallel to the resistor 110 an adjustable resistor 703 arranged.

Furthermore, locally adjacent LEDs may be grouped or optically coupled together to generate a mixed light. This type of grouping is indicated by the reference numbers 704 to 707 indicated.

The grouping has the advantage that similar types of LEDs can be used within an LED chain, the LED chains each having different types of LEDs. The combination of different LEDs can be done by the indicated grouping.

For example, in this way within a group 704 to 707 stacked arrays of LEDs for light mixing of different LEDs or binning groups are used.

The power distributions within for the LED chains 102 to 104 can by a suitable choice of resistors 108 to 110 be achieved.

Optionally, a current distribution and thus color location calibration can be achieved by setting or calibrating the emitter resistors.

These are exemplified in 7 the adjustable resistors 701 to 703 intended. Preferably, each of the adjustable resistors 701 to 703 significantly larger than the associated parallel resistance 108 to 110 ,

Where: _I102 · _R108 · _R701 / ( _R108 + _R701 ) = _I103 · _R109 · _R702 / ( _R109 + _R702 ) = = _I104 · _R101 · _R703 / ( _R101 + _R703 )

In particular, the power distribution on the LED chains 102 to 104 done by means of a pulse width modulation circuit. This further embodiment makes it possible to perform a color calibration or color control also later or as an additional feature during regular operation in an existing LED lighting system.

8th shows a schematic diagram based on 1 , A series connection of the LED chain 102 and a regulator 801 is with a series connection of the LED chain 103 and a regulator 802 as well as with a series connection of the LED chain 104 and a regulator 803 connected in parallel. The power source 112 controls the controllers 801 to 803 at.

Exemplary is in 8th a functional structure of the controller 801 shown. Accordingly, the other controllers 802 . 803 be constructed.

The regulator 801 includes the transistor 105 whose emitter has an electronic switch 805 and the resistance 108 with the node 111 connected is. Furthermore, an electronic switch 804 provided, which is the collector of the transistor 105 with the LED chain 102 combines. Finally, the base of the transistor 105 via an electronic switch 806 with the power source 112 connected. It should be noted that the electronic switch 804 to 806 at least partially optional.

At the electronic switches 804 to 806 they can be transistors or mosfets that can be activated by a control unit. In particular, it may be the electronic switches 804 to 806 to trade PWM switches. An option is that at least one of the electronic switches 804 to 806 (and possibly in the appropriate position with the controllers 802 . 803 ) is a PWM switch.

One option is to provide a PWM switching rhythm that de-energizes a fixed number of current paths (and thus LED strings) and turns on a different number of current paths (and therefore LED strings). This has the advantage that in the LEDs a constant current flows and Farbortverschiebungen be avoided. On the other hand, a color location change can be brought about deliberately by the same arrangement.

Another option is that the base of at least one transistor is disconnected from the common base potential when a fault occurs (LED chain interrupted) in the LED chain associated with the transistor. This function may be from the electronic switch already described above 806 be taken over.

This has the advantage that not all LEDs of the module or even of the entire system fail in the event of a failure of a single LED.

In a first case, the current for an LED string is interrupted when an LED in the LED string fails (power cut in the LED is interrupted). The available power can be redistributed to the remaining functional LED strings.

In a second case, the current is symmetrized if a LED within the LED string is shorted. This corresponds to a reduction of the forward voltage for the affected LED string.

Preferably, for this purpose, the components are designed so that they hold the higher performance in case of failure of at least one LED state. This is usually easily implemented with at least three parallel LED chains.

For example, the separation of a transistor of an LED chain from the common base potential can be effected by means of a MOSFET, which receives its gate drive from the LED chain.

nine shows a schematic circuit diagram illustrating how the transistor 107 by means of a mosfet 901 from the common base potential (indicated by a node 904 ) can be separated.

According to the above statements, for example 1 is the LED chain 104 in series with the transistor 107 and the resistance 110 connected. The power source 112 is according to nine however, with the node 904 connected to the source terminal of the mosfet 901 connected is. The drain connection of the mosfet 901 is with the base of the transistor 107 connected.

A voltage tap in the LED chain 104 (indicated by the node 903 ) is connected to the gate terminal of the mosfet 901 and about a resistance 902 with the node 111 connected.

Accordingly, the other parallel LED chains with regulators, indicated in nine through the boxes 905 and 906 , be executed, these too with the node 904 are connected accordingly.

In particular, it is advantageous if the voltage tap 903 as far down (near the transistor 107 ) in the LED chain 104 is provided because only errors in the LED chain 104 above the node 903 be recognized.

This problem is caused by another in nine shown embodiment avoided. At the node 903 is the cathode of a Zener diode 910 connected with a zener voltage slightly above the forward voltage of the remaining LEDs below the node 903 , The anode of the Zener diode 910 is with the collector of the transistor 107 connected. Thus, Zener diode 910 always out of service as long as these so-called "lower" LEDs are conducting. If one of the lower LEDs fails due to an interruption, the Zener diode takes over 910 the electricity in the LED chain 104 and thus keeps the normal operation of the control transistor 107 upright, so that apart from the "lower" LEDs of the LED chain under consideration, not a single additional LED of this chain, the module and finally the entire system is affected by this failure.

Although the invention has been further illustrated and described in detail by the at least one embodiment shown, the invention is not limited thereto, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

101

 power source

102-104

 LED chain

105-107

 npn transistor

108-110

 (Emitter) Resistance

111

 Node (reference potential, ground)

112

 (further) power source

113-116

 node

DL1-DL3

 diode

RL

 resistance

301

 resistance

302

 node

303

 resistance

304

 node

305

 resistance

306

 node

307

 Based busbar

501-502

 module

503

 electric wire

504

 alternating magnetic field

505

 module

507

 (Interface) connection

508

 (Interface) connection

509

 Measuring output of the power supply

551

 measuring input

552

 measuring input

555

 measuring input

561

 measuring input

562

 measuring input

565

 measuring input

601

 Measuring output of the power supply

701-703

 adjustable resistance

704-707

 Grouping of LEDs

801-803

 regulator

804-806

 electronic switch (for pulse width modulation)

901

 Mosfet

902

 resistance

903-904

 node

905-906

 LED chain and regulator

910

 Zener diode

Claims (22)

circuitry With at least two light chains connected in parallel, - with each light chain a regulator is connected in series, - Wherein a current of a working as a power source power supply is distributed to the light chains such that at least one controller in the branch with the highest voltage drop on the light chain has the highest gain or is operable in a saturated mode of operation. A circuit arrangement according to claim 1, wherein the remaining regulators are operable in a linear or quasi-linear mode of operation. Circuit arrangement according to one of the preceding claims, in which a luminous chain comprises a series connection of at least two semiconductor light-emitting elements, in particular light-emitting diodes. Circuit arrangement according to one of the preceding claims, in which the controller comprises at least one mosfet or an operational amplifier. Circuit arrangement according to one of the preceding claims, wherein the controller comprises at least one transistor. Circuit arrangement according to Claim 5, in which The regulator comprises a transistor, - Whose collector-emitter path is connected in series with an emitter resistor with the light chain in series and - Its base terminal is connected to the base terminals of the other controllers and to another power source. Circuit arrangement according to Claim 5, In which the regulator comprises a transistor, Whose collector-emitter path is connected in series with an emitter resistor to the light chain, - whose base terminal is connected to the base terminals of the other controllers, - With a further current source, which is connected in each case via a diode to the collector of the transistor, wherein the cathode of the diode facing in such a direction that a portion of the current from the further current source instead of through the base of the transistor can flow through its collector . - Wherein the further current source is connected directly, via a diode or via a resistor to the base terminal of the transistor. Circuit arrangement according to one of Claims 5, 6 or 7, in which the regulator comprises a transistor whose collector-emitter path is connected in series with an emitter resistor to the luminous chain and whose base terminal is connected to the base terminals the other regulator and a resistor connected to a voltage tap inside the light chain. Circuit arrangement according to one of the preceding claims, in which at least two semiconductor light elements of different light chains are arranged in a locally or optically grouped manner. Circuit arrangement according to one of the preceding claims, in which the current to the light chains can also be distributed by means of at least one pulse width modulation circuit. Circuit arrangement according to claim 10, wherein the means of the pulse width modulation circuit at a time a predetermined number of light chains is de-energized. Circuit arrangement according to one of the preceding claims, in which the controller for the affected luminous chain can be deactivated in the event of an error. Circuit arrangement according to claim 12, in which the error case comprises an interruption in the luminous chain. Circuit arrangement according to one of claims 12 or 13, wherein the controller can be deactivated via a mosfet, wherein the mosfet is controllable via a voltage tap within the light chain. Circuit arrangement according to one of the preceding claims, wherein a power requirement of the circuit arrangement can be signaled. Circuit arrangement according to claim 15, which has an identification resistor for signaling the power requirement. Circuit system comprising at least two circuit arrangements according to one of Claims 5 to 8, in which the base terminals of the regulators are connected to one another between at least two of the circuit arrangements. Circuit system comprising at least two of the circuit arrangements according to claim 16, In which the characteristic resistances of the circuit arrangements are connected in parallel, In which the characteristic resistances of the circuit arrangements are arranged between a reference potential and a measuring input, - wherein the measuring input is connectable to the power supply, Wherein a measuring voltage can be applied between the measuring input and the reference potential, - Where the current through the measuring input is measurable and - Wherein the source supply current is proportional to the current measured at the measuring input adjustable, in particular controllable, from the power supply. A circuit system according to claim 18, wherein a relation of the emitter resistance and the characteristic resistance for a circuit arrangement is the same for the circuit arrangements of the circuit system. Circuit system comprising at least two circuit arrangements according to claim 16 In which the characteristic resistances of the individual circuit arrangements are connected in series, In which the identification resistors are arranged between a reference potential and a measuring input, - wherein the measuring input is connectable to the power supply, - Wherein a measuring current is available at the measuring input, - where the voltage between the measuring input and the reference potential is measurable and - Whose source power is proportional to the voltage measured between the measuring input and the reference potential adjustable, in particular controllable from the power supply. A circuit system according to claim 20, wherein a product of the emitter resistor and the characteristic resistor is the same for the same circuit arrangement for the circuit arrangements of the circuit system. Method for controlling a plurality of parallel-connected luminous chains, - with each light chain a regulator is connected in series, - In which a current of a working as a power source power supply is distributed to the light chains such that at least one controller in the branch with the highest voltage drop on the light chain has the highest gain or is operable in a saturated mode of operation.

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