LED module

Abstract

The invention relates to an LED module (1), comprising: connections (2) for an LED series (3); a circuit (4), which is designed to constitute a load, preferably an active-power load, when a first supply voltage (5a) not equal to zero is applied to the LED module (1), which active-power load is dimensioned in such a way that, when an LED series (3) is connected, said LED series is not conductive, and which is designed to constitute no load when a second supply voltage (5b) not equal to zero is applied to the LED module (1), for which second supply voltage, when an LED series (3) is connected, said LED series is conductive and light is emitted, wherein the type of load change is selected in dependence on the value of the first supply voltage and/or a modulation of the first supply voltage.

Claims

1. An LED module (1) comprising: voltage connections (12); connections (2) for an LED series (3); a circuit (4) which is configured and arranged to constitute: a variable current at the volts, e connections (12) when a first supply voltage (5a) not equal to zero is applied to the voltage connections (12) of the LED module (1), the first supply voltage (5a) being dimensioned in such a manner that, in a case of a connection of an LED series (3), the latter is not conductive, wherein the variable current load effects a change in a power consumption of the LED module (1) according to a specified protocol, and no load when a second supply voltage (5b) not equal to zero is applied to the voltage connections (12) of the LED module (1), at which, in the case of connection of the LED series (3), the latter is conductive and light is emitted, wherein the type of the load constituted by the circuit (4) is selected dependent upon the value of the first supply voltage and/or of a modulation of the first supply voltage, wherein a voltage range of the first supply voltage (5a) is subdivided into a plurality of sub-ranges and wherein each sub-range corresponds to a different specified protocol wherein, for each of the plurality of sub-ranges, the circuit (4) is configured to effect a change of the variable current load dependent on a value of the first supply voltage (5a) according to the specified protocol, of the sub-range, wherein for each sub-range a different change of the power consumption of the LED module (1) is present.

2. The LED module (1) according to claim 1, wherein the circuit (4) is designed to code at least one operating and/or maintenance parameter of the LED module (1) through a change in the power consumption of the LED module.

3. The LED module (1) according to claim 1, wherein the at least one specified protocol specifies a frequency and/or an amplitude and/or a duty factor of a change in the power consumption of the LED module (1).

4. The LED module (1) according to claim 1, wherein the circuit (4) comprises a timer circuit (6), which is designed to specify a frequency of the change in a power consumption of the LED module (1).

5. The LED module (1) according to claim 1, wherein the circuit (4) is integrated in a semiconductor material of the LED module (1).

6. The LED module (1) according to claim 1, wherein at least one sensor is provided on the LED module (1), which is designed to influence an electrical parameter of the circuit (4).

7. The LED module (1) according to claim 6, wherein the at least one sensor is a light sensor with light-dependent resistance, and the light sensor is connected to the circuit (4) in such a manner that a change of the light-dependent resistance changes the load resistance of the circuit (4).

8. An LED converter (10) in combination with the LED module (1) according to claim 1, wherein the LED converter (1) comprises a high-frequency clocked converter, wherein the high-frequency clocked converter is configured and arranged to selectively match the supply voltage of the LED module and is designed, to register the power consumption of the LED module (1) on the primary side of the transformer of the high-frequency clocked converter, and, based on the registered power consumption, to determine at least one operating and/or maintenance parameter of the LED module (1).

9. The LED converter (10) according to claim 8, which is designed to use the at least one determined operating and/or maintenance parameter: for the adjustment or control of the operation of the LED module (1), to store it in an associated memory/store, to display it visually and/or acoustically, and/or to transmit it via a wireless or tethered interface, optionally upon request from externally.

10. The LED converter (10) according to claim 8, wherein the at least one operating and/or maintenance parameter is a set current through an LED series (3) connected to the LED module (1), an ageing parameter, an operating duration, and/or a spectrum of a light emitted by the LED series (3).

11. The LED converter (10) according to claim 8, which is designed to identify the LED module (1) based upon the at least one determined operating and/or maintenance parameter.

12. The LED converter (10) according to claim 8, which is designed, through adjustment of a first supply voltage (5a) or a second supply voltage (5b), for the LED module (1), to switch selectively between a mode for the registration of a power consumption of the LED module (1) and a mode for the lighting operation of an LED series (3) connected to the LED module (1).

13. The LED converter (10) according to claim 8, which is designed to implement a current measurement for the direct registration of the power consumption of the LED module (1).

14. The LED converter (10) according to claim 8, which is designed to implement an indirect registration of the power consumption of the LED module (1).

15. The LED converter (10) according to claim 14, which is designed to register a change in the power consumption of the LED module (1) through a change in a duty factor of a clocking of the LED converter (10).

16. The LED converter (10) according to claim 8, which is designed to discharge a capacitor (11) via a load of the LED module (1), to determine a discharge current of the capacitor (11) directly, or indirectly via a discharge time, and to determine the at least one operating and/or maintenance parameter of the LED module (1) based on this discharge current.

17. A method for determining information regarding an LED module (1) according to claim 1 performed by an LED converter (10) wherein the LED converter (10) comprises a high-frequency clocked converter, the method comprising: applying the first supply voltage (5a) not equal to zero to the LED module (1), wherein the first supply voltage (5a) is dimensioned in such a way that in case of the connection of the LED series (3), the latter is not conductive, registering the power consumption of the LED module (1) by the high-frequency clocked converter, wherein the circuit (4) on the LED module (1) causes a modulated load change during a start phase, and determining at least one operating and/or maintenance parameter of the LED module (1) based on the registered power consumption.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is now described in greater detail with reference to the attached Figures.

(2) FIG. 1 shows schematically the basic principle of the present invention on the basis of an LED luminaire according to the invention (comprising an LED module according to the invention and an LED converter according to the invention).

(3) FIG. 2 shows a current-voltage characteristic of an LED series and the readout window according to the invention.

(4) FIG. 3 shows an integrated circuit which allows an automatic deactivation of the circuit on the LED module according to the invention.

(5) FIG. 4 shows an example of the circuit on the LED module according to the invention which constitutes a constant-current load.

(6) FIG. 5 shows schematically the registration of a constant-current load on the LED module according to the invention through the LED converter according to the invention.

(7) FIG. 6 shows a circuit on the LED module according to the invention, which constitutes a variable-current load and, in particular, adjusts a frequency of the change in the power consumption of the LED module according to the invention.

(8) FIG. 7 shows how a change in the power consumption of the LED module according to the invention can be measured in a buck converter as an example of an LED converter according to the invention.

(9) FIG. 8 shows how a change of the current through the circuit on the LED module according to the invention correlates with the current in a buck converter of the LED converter according to the invention.

(10) FIG. 9 shows a further example of the circuit on the LED module according to the invention.

(11) FIG. 10 shows a further example of the circuit on the LED module according to the invention.

(12) FIG. 11 shows a further example of the circuit on the LED module according to the invention.

(13) FIG. 12 shows a further example of the circuit on the LED module according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(14) FIG. 1 shows schematically an LED luminaire according to the invention, which comprises an LED module 1 according to the invention and an LED converter 10 according to the invention. The LED converter 10 is connected via one or more voltage connections 12 to the LED module 1. The LED converter 10 therefore supplies the LED module 1 with a supply voltage. The LED converter 10 can also be designed for the operation of several LED modules 1. By preference, the supply voltage is a DC voltage, but can also be a clocked voltage or AC voltage. The LED converter 10 preferably comprises a high-frequency clocked converter, for example, a buck converter (stepdown converter), isolated flyback converter (flyback converter) or a resonant half-bridge converter (preferably isolated, for example, an LLC converter). The LED converter 10 can output, for example, a constant output voltage or a constant output current to its voltage connections 12, wherein the voltage at these connections corresponds to the supply voltage of the LED module 1.

(15) The supply voltage is applied via one or more connections 2 of the LED module 1 to at least one LED series 3 connected to it (this also comprises an individual LED). The LED series 3 need not be a part of the LED module 1 according to the invention, but can be a connectable and replaceable LED series 3. The LED module 1 according to the invention therefore requires only connections 2 for at least one LED series 3. The LED series 3 can, however, also be rigidly assembled with the LED module 1. The LED series 3 can comprise one or more LEDs, which are connected in series, for example, as shown in FIG. 1. LEDs of an LED series 3 can all illuminate in the same colour, that is, emit light of the same wavelength, or illuminate in different colours.

(16) For example, several LEDs, preferably red, green and blue illuminating LEDs, can be combined in order to generate a mixed radiation of preferably white light.

(17) When it is connected to the connections 2, the LED series 3 is configured in parallel with a circuit 4 with reference to the supply voltage. The circuit 4 is embodied, for example, in such a manner that it constitutes a load, preferably an active-power load, for the LED converter 10, when the supply voltage applied from the LED converter 10 to the connections 12 is not equal to zero, but is still no low that the LED series 3 connected to the connections 2 is still not conductive. The circuit 4 can therefore also be designated as a load circuit or load-modulation circuit.

(18) FIG. 2 shows by way of example a current-voltage characteristic of an LED series 3, in which a current through the LED series is plotted in the vertical direction, and the voltage in the LED series (that is, the supply voltage in FIG. 1) is plotted in the horizontal direction. For a first voltage range (that is, a first supply voltage 5a within the readout window), the voltage in the LED series 3 is not equal to zero, however, the current through the LED series 3 is also still close to zero, because the LED series 3 is not conductive. The supply voltage is therefore below the let-through voltage. The LED series 3 constitutes an infinite load for the LED converter 10. Accordingly, the LED module 1 consumes no power via the LED series 3. Within a second voltage range (that is, for a second supply voltage 5b outside the readout window), the LED series 3 is conductive, and a current flows through the LED series 3, which causes the latter to illuminate. The supply voltage is therefore above the let-through voltage.

(19) The circuit 4 is embodied on the LED module 1, for example, in such a manner that it is activated when the first supply voltage applied, and accordingly constitutes a load, preferably an active-power load, for the LED converter 10. For the second supply voltage 5b, that is, in the lighting mode of the LED series 3, the circuit 4 is deactivated and does not constitute a load for the LED converter.

(20) This is illustrated schematically in FIG. 1 by the switch 6, which automatically activates or deactivates the circuit 4 dependent upon the supply voltage applied. The circuit 4 can constitute either a constant-current load or a variable-current load for the LED converter 10. The circuit 4 causes a power consumption of the LED module 1, although an LED series 3 is still not yet conductive and consumes no power. A conventional LED module 1 would consume no power within the readout window. Additionally, or alternatively, the circuit 4 can also be embodied on the LED module 1 in such a manner that it is only activated in a time-limited start phase of the LED module 1.

(21) The power consumption of the LED module 1 in the readout window can be constant-current or variable-current dependent upon the type of the circuit 4. The LED converter 10 can register the power consumption of the LED module 1 or respectively a change in the power consumption of the LED module 1 and, based on the registered power consumption, infer operating and/or maintenance parameters of the LED module 1 to be adjusted. The LED converter 10 can use the operating and/or maintenance parameters directly for the adjustment or control of the LED module 1. The LED converter 10 can, however, also store the operating and/or maintenance parameters in a memory allocated to it and optionally use them later, or display the parameters visually and/or acoustically to a user, or transmit them to a further device, for example, a control unit of a lighting system. The transmission can occur either in a wireless or in a tethered manner and can be implemented either automatically or only upon request from the further device.

(22) In order to operate an LED module 1, different procedures can be implemented by the LED converter 1 of the present invention in a preferably time-limited start phase of the LED luminaire. Initially, the LED converter 10 supplies the LED module 1, for example, with a constant supply voltage, preferably a constant DC voltage. The LED converter 10 can be operated, for example, with reduced pulse control factor by comparison with the normal operation, thereby achieving lower output voltage. In this context, the supply voltage is a first supply voltage 5a, that is, it is disposed within the readout window which is shown in FIG. 2. Since the first supply voltage 5a is not equal to zero, the circuit 4 on the LED module 1 is activated and constitutes a load for the LED converter 10. The load is preferably an active-power load and generates a power consumption of the LED module 1. Now, the LED converter 10 can, for example, measure a discharge current of a capacitor via this load, an absolute current consumption of the circuit 4, a frequency of a change in the power consumption of the LED module 1, or a duty factor or an amplitude of a power-consumption change. Based on the result of the measurement, the LED converter 10 can infer operating and/or maintenance parameters.

(23) For example, the LED converter 10 can determine a set or let-through voltage or a set current of the LED module and apply the latter to the LED module 1. Accordingly, a connected LED series 3 becomes conductive, and the LED converter 10 operates the LED module 1 in the lighting mode. The circuit 4 is now preferably automatically deactivated. Accordingly, the circuit 4 consumes no power in the lighting mode of the LED series 3 and therefore does not influence lighting mode of the LED series 3. The LED converter 10 of the LED luminaire has therefore automatically detected the LED module and adjusted the matching operating parameters.

(24) Alternatively, or additionally, a reading out of the LED module 1 by the LED converter 10 can also take place in a time-limited manner, in that the circuit 4 is active only during a start phase because of a specified time span, as soon as a supply voltage is applied to the LED module 1. In this case, this supply voltage can also correspond to the nominal output voltage of the LED converter 10 for the normal mode. After the application of the supply voltage, the circuit 4 is activated on the LED module 1 and constitutes a load for the LED converter 10. The load is preferably an active-power load changing repeatedly and generates a power consumption of the LED module 1. Additionally, in this case, the connected LED series 3 can also become conductive, wherein the LED converter 10 operates the LED module 1 in the lighting mode.

(25) Now, the LED converter 10 can, for example, measure a discharge current of a capacitor across this load, an absolute current consumption of the circuit 4, a frequency of a change in the power consumption of the LED module 1, or a duty factor or an amplitude of the power consumption change. Based on the result of the measurement, the LED converter 10 can infer operating and/or maintenance parameters. For example, the LED converter 10 can determine a set or let-through voltage or a set current of the LED module and apply the latter to the LED module 1. By preference, the circuit 4 is now automatically deactivated after the expiry of the specified time span for the start phase. The specification of this time span for the start phase can be established, for example, through a time-charge circuit, wherein a timer-capacitor is charged up and, the circuit 4 is deactivated after the completed charging of the timer-capacitor. Accordingly, the circuit 4 consumes no power in the continuous lighting mode of the LED series 3 and therefore does not influence the lighting mode of the LED series 3.

(26) FIG. 3 shows an integrated circuit which is at least a part of the circuit 4 in order to activate the latter automatically when the supply voltage is within the range of the second supply voltage 5b, that is, above the let-through voltage of the LED series 3. The circuit 4 can be deactivated by means of the transistors M4 and M3. With rising supply voltage, which is delivered by the LED converter 10 and is present in the circuit 4 on the LED module 1, the voltage in the resistor R8 also rises. When this voltage reaches a threshold voltage of the transistor M4, the latter closes and also deactivates the transistor M3 by connecting the gate voltage of the transistor M3 to ground. The threshold voltage can be, for example, 1.4 V (in the case of a voltage of 12.5 V) of the LED converter 10). In order to reduce losses of the voltage splitter R8 and R10, the resistance values should be high, preferably within the range from 20 to 200 k, by greater preference within the range from 40 to 100 k. Furthermore, it is important that the transistor M3 is designed to withstand the maximal supply voltage which the LED converter 10 can apply, and that the voltage in the resistor R8 does not exceed the maximal permitted gate voltage of the transistor M4 in the case of normal lighting mode of the LED series 3. Alternatively, or optionally, this circuit can be designed, for example, by means of an RC element, in such a manner that, after the expiry of a specified start time (wherein this time corresponds to the start phase), it is deactivated, in that the transistor M3 is deactivated, that is, opened, independently of it. For example, a capacitor can be arranged in parallel to the resistor R8. This capacitor can be designed in such a manner that, after the expiry of the specified start time, the latter is charged by the applied supply voltage, and accordingly, the voltage in the parallel resistor R8 has also risen so far that the voltage has readied a threshold voltage of the transistor M4, so that the latter closes and deactivates the transistor M3 by connecting the gate voltage of the transistor M3 to ground.

(27) FIG. 4 shows, by way of example, an integrated circuit TL432, which is at least a part of the circuit 4, which is designed to constitute a constant-current load for the LED converter 10 in the readout window. The left side of the FIG. 4 shows a circuit diagram of the integrated circuit; the right side shows a corresponding equivalent circuit diagram for the integrated circuit TL431 or TL432. The constant current is determined by a ratio of the reference voltage of the integrated circuit TL431 to the resistance value of the selection resistor R11 (Rcfg). A transistor Q1 is preferably controlled in such a manner that the voltage in the resistor R11 (Rcfg) is always approximately 2.5 V. A minimal current of approximately 1 mA should flow through the integrated circuit TL431. The integrated circuit shown in FIG. 3 can be arranged in series with the integrated circuit shown in FIG. 4, so that the series circuit comprising both is arranged parallel to the LED series on the LED module 1. By preference, the virtual ground GNDX of the integrated circuit of FIG. 4 is connected to the drain connection of the transistor M3.

(28) Via a constant-current load, such as is shown in FIG. 4, the LED converter 10 can, for example, discharge a capacitor 11 for the measurement of the constant current. The constant current through the circuit 4 (which corresponds to the discharge current of the capacitor 11) can be determined directly or indirectly based upon either the discharge duration and/or the discharge rate. Based on the discharge current, the LED converter can infer the circuit 4 used and therefore the LED module 1 connected. Furthermore, the LED converter 10 can determine operating and/or maintenance parameters of the LED module, for example, on the basis of stored tables.

(29) The concept for determining the constant current through the circuit 4 is illustrated schematically in FIG. 5. For example, the LED converter 10 can be embodied, by way of example, as a buck converter. The LED converter 10 is provided with the capacitor 11, which can be connected parallel to the connections 12 for the supply voltage. The voltage at the connections 12 is monitored by the LED converter 10. If the supply voltage is separated from the LED module by opening the switch 13, which is arranged in the LED converter 10 and preferably clocked in a high-frequency manner during operation of the LED converter, the capacitor 11 is discharged via the preferably constant-current load, which is constituted by the circuit 4 on the LED module 1. The discharge rate, that is, the change of the voltage of the capacitor, which is present at the connections 12, is preferably measured by the LED converter 10 in order to infer the operating and/or maintenance parameters of the LED module 1, as described. For example, the resistor R 11, of the constant-current load shown in FIG. 4 can be determined, if the capacitance of the capacitor 11 is known. This resistance value can then encode the operating and/or maintenance parameter, that is, the LED converter 10 can, for example, correlate this resistance value with operating and/or maintenance parameters in buffered tables.

(30) FIG. 6 shows an integrated circuit TLC555, which is at least a part of the circuit 4 and is suitable for generating a load change of the LED module 1 with a given frequency, that is, a change in the power consumption of the LED module 1. On the left side of FIG. 6, a circuit diagram is shown, on the right side a corresponding equivalent circuit diagram is shown for the integrated circuit TLC555. For example, a capacitor C1 can be charged and discharged between and of the supply voltage 5a applied by the LED converter. So long as the supply voltage 5a applied from the LED converter 10 is constant, a frequency of the load change, a duty factor (clock ratio) of the load change or an amplitude of the load change (that is, a difference between a load before and a load after the change) can be adjusted. This also determines a change in the power consumption with a corresponding frequency, duty factor (clock ratio) or an amplitude.

(31) The frequency f of the change is defined in this context as
f=1/{R3+2.Math.R4)C1.Math.ln(2)},
Wherein R3, R4 and C1 are resistance and respectively capacitance values of the components shown in FIG. 6.

(32) The duty factor (clock ratio) is defined by the ON time (T.sub.high) and the OFF time (T.sub.low), wherein
(T.sub.high)=(R3+R4)C1.Math.ln(2) and
(T.sub.low)=R4C1.Math.ln(2).

(33) The change of the duty factor is possible both through a change of the pulse duration (switch-on duration, ON time, T.sub.high) and also by a change in the pause duration switch-off time, OFF time, T.sub.low).

(34) The magnitude of the load is determined by the resistor R5 and the converter voltage V.sub.CONV (more precisely, the ratio V.sub.CONV/R5).

(35) The circuit 5 can be designed, for example, in such a manner that it is activated only during the start phase of the LED luminaire. This can be achieved, for example, in that the supply of the integrated circuit TLC 555 can by means of a time element, such as an RC element, for example, this time element be designed in such a manner that the supply for the integrated circuit TLC 555 is applied only for a time of, for example, 100 ms, and after this, because of charging up of the capacitor of the RC element, via a pre-resistor (starting from the supply voltage of the LED module 1), a specified voltage level is reached, which leads to a switching off of the supply voltage Vcc for the integrated circuit TLC555 (example not illustrated). For example, via the voltage declining in the element, the base of a switch-off transistor (not illustrated) can be controlled, which draws the supply Vcc for the integrated circuit TLC555 to ground, as soon as the RC element has been charged up. In this context, the charging time of the RC element can be designed in such a manner that a time of, for example, 100 ms is reached, wherein this time corresponds to the start phase. A start-up of the integrated circuit TLC555 at the beginning of the start phase can be implemented through a high-ohmic feed directly from the supply voltage of the LED module 1, wherein, at the end of the start phase, the latter is drawn to ground by means of the voltage declining in the RC element via the switch-off transistor in a kind of pull-down configuration. The circuit 4 can comprise a controllable switch, which adds or subtracts the resistor R5 dependent upon the output signal OUT of the integrated circuit TLC555.

(36) The integrated circuit shown in FIG. 3 can be arranged in series with the integrated circuit shown in FIG. 6, so that the series circuit of both is arranged in parallel to the LED series on the LED module 1. By preference, the virtual ground GNDX of the integrated circuit of FIG. 6 is connected to the drain terminal of the transistor M3. A deactivation of the integrated circuit of FIG. 6 can take place, for example, in a time-controlled manner. As already explained with the example of FIG. 3, a capacitor can be arranged in parallel to the resistor R8. In this case, an RC element is also formed. The charging time of the RC element in this context can be designed in such a manner that a time of, for example, 100 ms is reached, wherein this time corresponds to the start phase. After the expiry of the start time specified by the dimensioning of the RC element, the voltage at the gate of the transistor 4 has reached a threshold voltage of the transistor M4, so that the latter closes and deactivates the transistor M3, by setting the gate voltage of the transistor M3 to ground. In this manner, the circuit of FIG. 6 can be activated only for a predetermined start phase.

(37) If a repeatedly varying load change (that is, a modulated load change) is generated and output by the circuit 4, for example, two different items of information can also be transmitted. For example, both the frequency and also the duty factor of the load change can be varied. In this case, a first information (for example, the set voltage) could be transmitted, coded by means of the frequency, while a second information (for example, the set current) could be transmitted, coded via the duty factor. A further possibility for the combined transmission of at least two items of information would be the corresponding change in the pulse duration (switch-on duration, ON time, T.sub.high) and the pause duration switch-off duration, OFF time, T.sub.low) of the load change.

(38) The change in the power consumption of the LED module 1 can be determined by the LED converter 10, for example, by direct current measurement of the current through the circuit 4. Alternatively, the LED converter 10 can implement measurements in a buck converter as shown in FIG. 7, wherein the buck converter is preferably a part of the LED converter M. For example, FIG. 8 shows how the current through the circuit 4 and the current in the buck converter which is measured via a shunt, correlates. FIG. 8, at the top, shows the current load current through circuit 4 and the current inductor current through the buck converter plotted against time. In this context, the buck converter constitutes only an exemplary instance of a high-frequency clocked converter, alternatively, for example, an isolated flyback converter, boost converter (step-up converter) or a resonant half-bridge converter preferably isolated, for example, an LLC converter) can be used for feeding the LED module 1.

(39) As shown in FIG. 7, the LED converter can comprise a buck converter. The buck converter can be operated as constant-current source, that is, controlling to a constant output current. In this case, for example, the output voltage of the buck converter, that is, the voltage which is output at the output of the LED converter 10 and which corresponds to the voltage across the LED module 1, can be registered and evaluated. Additionally, or alternatively, the duration of the switch-on time and the switch-off time of the control of the high-frequency clocked switch of the buck converter can be monitored and evaluated in order to detect a load change and therefore to read out an information from the LED module 1.

(40) The buck converter can also be operated as a constant-voltage source, that is, controlling at a constant output voltage. In this case, a load change in the LED module 1 will lead to a change of the peak current to be adjusted through the high-frequency clocked switch during the switch-on the phase of the high-frequency clocked switch of the buck converter, wherein this change can be registered. Additionally, or alternatively, the duration of the switch-on time and of the duty factor of the control of the high-frequency clocked switch of the buck converter can also be monitored and evaluated in order to detect a load change and accordingly to read out an information from the LED module 1. Alternatively, in the case of an operation as constant-voltage source, the level of the output current can also be evaluated in order to detect a load change.

(41) The buck converter can be operated with a fixed duty factor at a fixed frequency, preferably in a continuous conduction operating mode (continuous conduction mode). With an operation of this kind, the level of the output current and/or output voltage can be evaluated in order to detect a load change.

(42) The buck converter of the LED converter 10 can supply the LED module 1 with a constant supply voltage, preferably a constant DC voltage, for example, in a start phase. In this case, the buck converter is operated as a constant-voltage source in the start phase. For example, the LED converter 10 can be operated with reduced switch-on ratio by comparison with normal operation, thereby reaching a reduced output voltage. In this context, the supply voltage can be a first supply voltage 5a, that is, it can be disposed within the readout window, which is shown in FIG. 2. The buck converter can also supply the LED module 1 with a controlled current in a start phase, the buck converter is then preferably operated as a constant-current source.

(43) FIG. 8, at the bottom, shows an enlarged view of this characteristic. The greater the load of the circuit 4, the greater a duty factor or a peak current in the measurement resistor (shunt) will be. Dependent upon a control principle of the LED module 1 through the LED converter 10, a peak-current can also be measured in the shunt of the buck converter or also a change in the duty factor in the buck converter. The change in the load of the circuit 4 or respectively the power consumption of the LED module 1 can be registered directly in the shunt at the low-potential switch of the buck converter. Either through a periodic change of the duty factor or a periodic change of the peak-current, which correlates with a periodic change in the power consumption of the LED module 1.

(44) As already mentioned, the LED converter 10 can comprise, for example, an isolated converter with a transformer for the high-frequency energy transmission (isolated, preferably an isolated flyback converter) for the supply of the LED module 1. If the LED converter 10 is embodied in an isolated manner (for example, as an isolated flyback converter), and therefore comprises a transformer, the registration of the load change through the LED converter 10 can also take place on the primary side of the LED converter 10.

(45) For example, the current on the primary side of the LED converter 10, which flows through the primary side of the transformer, can be registered with the use of an isolated flyback converter. In this context, for example, the current through the clock switch, which is arranged in series with the primary winding of the transformer, but also the current through the primary winding of the transformer, can be registered, preferably, by means of a shunt (current-measuring resistor) connected in series to the latter. For example, the applied load or also the load change of the LED module 1 and therefore, for example, a change in the duty factor on the primary side of the LED converter 10 can be measured on the basis of the peak-current in the shunt. For example, the change in the primary-side current against time can also be registered. For example, a registration of the power transmitted from the primary side can be implemented on the basis of the measurement of the primary-side current and a measurement or at least the knowledge of the voltage feeding the converter. It would be possible, for example, for an active power-factor correction circuit, such as a step-up circuit to be connected upstream of the converter, which delivers the input voltage for the high-frequency clocked, isolated converter, for example, the isolated flyback converter and controls it to a specified value. This specified value for the input voltage controlled by the active power-factor correction circuit for the high-frequency clocked converter is known on the basis of the specification (for example, via a voltage splitter) and can therefore be taken into consideration in registering the power transmitted from the primary side.

(46) As already mentioned, the LED converter can comprise an isolated flyback converter (flyback converter). The isolated flyback converter can be operated as a constant-current source, that is, controlling to a constant output current. In this case, for example, the output voltage of the isolated flyback converter, that is, the voltage which is output at the output of the LED converter 10 and corresponds to the voltage across the LED module 1, can be registered and evaluated. This output voltage can be registered directly or also indirectly, for example, by means of a measurement of the voltage in a primary-side winding of the transformer of the isolated flyback converter. Additionally, or alternatively, the duration of the switch-off time of the control of the high-frequency clocked switch of the isolated flyback converter can be monitored and evaluated in order to detect a load change and accordingly to read out an information from the LED module 1.

(47) The isolated flyback converter can also be operated as a constant-voltage source, that is, controlling to a constant output voltage. In this case, a load change in the LED module 1 will lead to a change of the output current, wherein this change can be registered. This change of the output current can lead, for example, to a change of the peak current to be adjusted through the high-frequency clocked switch during the switch-on phase of the high-frequency clocked switch of the isolated flyback converter. The monitoring of the primary-side current through the high-frequency clocked switch can therefore be exploited for the monitoring of a load change in order to read out an information from the LED module 1 in this manner.

(48) The isolated flyback converter can also be operated with a fixed duty factor at a fixed frequency. In the case of such an operation, the level of the output current and/or the output voltage can be evaluated in order to detect a load change. If only the LED series of the LED module is active, the output voltage will assume the value of the let-through voltage of the series. If a load change through the circuit 4 takes place, the output voltage will decline. This change can be registered as a load change.

(49) As already mentioned, the LED converter can comprise an isolated, resonant half-bridge converter, such as a so-called LLC converter. The converter can be operated as a constant-current source, that is, controlling at a constant output current. In this case, for example, the output voltage of the isolated flyback converter, that is, the voltage which is output at the output of the LED converter 10 and corresponds to the voltage across the LED module 1, can be registered and evaluated. This output voltage can be registered directly or also indirectly, for example, by means of a measurement of the voltage at a primary-side winding of the transformer of the LLC converter. If only the LED series of the LED module is active, the output voltage will assume the value of the let-through voltage of the LED series. If a load change through the circuit 4 takes place, the output voltage will decline. This change can be registered as a load change. Additionally, or alternatively, the clock frequency of the LLC converter adjusted on the basis of the control loop can also be monitored and evaluated in order to detect a load change and therefore to read out an information from the LED module 1. If the control loop of the LLC converter is designed in such a manner that, in the case of the load change through the circuit 4, a frequency stop of the control of the half bridge of the LLC converter is reached, this can also be evaluated in order to read out the information.

(50) The isolated, resonant half-bridge converter, for example, LLC converter, can also be operated as a constant-voltage source, by operating it at fixed frequency, wherein the frequency is selected in such a manner that the resulting voltage at the output is disposed below the value of the let-through voltage of the LED series. In this case, a load change in the LED module 1 will lead to a change in the output current, wherein this change can be registered. This change in the output current can take place, for example, on the secondary side of the LLC converter and can be transmitted to the primary side by means of a coupling element, such as a current transformer. The monitoring of the output current can therefore be exploited for the monitoring of a load change, in order to read out an information from the LED module 1 in this manner.

(51) The LED converter 10 is operated, for example, in a start phase, in a given mode, for example, in a fixed-frequency mode, or alternatively, also operated as current source or voltage source in order to detect a load change and accordingly to read out an information of the circuit 4, which is transmitted, for example, according to at least one protocol.

(52) The circuit 4 can also comprise a digital control unit IC1, which is designed to output different types of modulated signals as preferably modulated load change, for example, also a given pulse sequence as digital coding (sequence of zeros and ones). The converter 10 can be designed to interrogate different types of information, that is, different operating parameters and/or maintenance parameters, from the LED module 1 through a change of the supply voltage, and also to interrogate selectively one of several LED modules. The change in the supply voltage can take place, for example, by means of a low-frequency (within the range of a few Hz up to one kHz) or high-frequency modulation (within the range of several tens or hundreds kHz or up to the megahertz range).

(53) The digital control unit IC1 of the circuit 4 can be embodied as an integrated circuit. For example, the integrated circuit can be embodied as an integrated control circuit with only three or four connections.

(54) In an embodiment with three connections, the digital control unit IC1 would have a first connection Vp, which is connected to the supply voltage of the LED module 1 (FIG. 9). Via this first connection Vp, the digital control unit IC1 can register the supply voltage of the LED module 1 by means of the first analog-digital converter A/D1 connected to this connection Vp. A second connection Vn is connected to the ground of the LED module 1 and allows an internal ground connection within the digital control unit IC1. A third connection Vdd can be connected to a capacitor, which is also connected to the ground of the LED module 1 with its other connection. The second connection Vp can be connected internally via a diode and a switch Svdd to the first connection Vp. This switch Svdd can be compared, dependent upon a comparison of the current voltage present at the connection Vdd, with a reference value Ref by means of a comparator Comp1. Dependent upon the result of the comparison, the switch Svdd can be switched on by the driver unit VddCtrl, when the actual value of the voltage at the at the connection Vdd is smaller than the reference value Ref. A current then flows via the switch Svdd into the capacitor which is connected to the third connection Vdd. The voltage present at the third connection Vdd can be used as an internal voltage supply for the digital control unit IC1. In this case, the connection Vdd serves to stabilise the internal voltage supply of the digital control unit IC1.

(55) According to this example, the digital control unit IC1 can be programmed in advance, for example, during the manufacture or fitting of the LED module 1. This programming of the digital control unit IC1 can specify, for example, an operating parameter of the LED module 1, such as a set current or the set voltage.

(56) In the digital control unit IC1, a switch element S6 is integrated, which corresponds in function to the switch 6 in the example of FIG. 1 and is designed to output at least one modulated signal or also different types of modulated signals, preferably as modulated load change. In this context, the voltage at the first connection Vp is connected internally by closing the integrated switching element S6, directly or indirectly to the second connection Vn, for example, via an integrated resistor R6, and therefore draws the voltage at the connection Vp to a lower potential. For example, the modulated signal can be a given pulse sequence and can be output as digital coding (sequence of zeros and ones). By means of the switch element S6, the digital control unit IC1 can therefore communicate an information, for example, in a start-up phase (that is, a time-limited start phase of the LED converter and LED module 1), preferably according to the at least one protocol, which is stored in the LED module 1 and in the LED converter 10. The current through the switching element S6 can be monitored by means of the resistor R6, wherein the switching element S6 can be opened if the current through the switching element S6 and accordingly the resistor R6 becomes too large. The registration of the voltage declining across the resistor R6 and accordingly of the current flowing through it, can be implemented by means of a second analog-digital converter A/D2. The reading out and evaluation of the two analog-digital converters and the control of the switch element S6 can be implemented through a control block Config and Com integrated in the digital control unit IC1. All further operations, such as signal evaluations and outputs, can also be implemented through this control block.

(57) In the digital control unit IC1, for example, a sensor unit for the registration of the temperature can, for example, also be integrated, wherein the digital control unit IC1 can communicate an over-temperature or an operating temperature to the LED converter as a maintenance parameter, as information according to the at least one protocol. As maintenance parameter, the digital control unit IC1, can, for example, also comprise a counter for the operating time, and the digital control unit IC1 can be designed for this purpose to output as maintenance parameter an ageing parameter of the LED module or respectively of the LED series, or an operating duration of the LED module.

(58) The digital control unit IC1 can also register an overvoltage in the LED module 1 and output a corresponding error message as maintenance parameter. Optionally, or alternatively, by closing the switching element S6, the LED series of the LED module 1 can be bridged and therefore protected from the overvoltage.

(59) FIG. 10 shows an embodiment of the digital control unit IC1 with four connections. The digital control unit IC1 comprises a fourth connection Cfg, at which a configuration element, such as a resistor Rcfg (selection resistor R11) can be connected. A controllable current source Icfg can be connected internally to this fourth connection Cfg. The voltage declining across the resistor Rcfg, which is obtained on the basis of the current fed in through the controllable current source Icfg and the resistance value of the resistor Rcfg, can be registered by the control block Config and Com of the digital control unit IC1 via a third analog-di tat converter A/D3. This registered voltage at the fourth connection Cfg can specify an operating parameter of the LED module 1, such as the set current or the set voltage. Optionally, for example, a temperature-dependent resistance can be arranged between the fourth connection Cfg and the third connection Vdd. The temperature-dependent resistor can be designed in such a manner that its resistance changes strongly in the case of an over-temperature on the LED module 1, so that the voltage at the fourth connection Cfg also changes. This change can be registered by the digital control unit IC1, and, for example, as a maintenance parameter, an over-temperature can be communicated to the LED converter as information according to the at least one protocol. For example, an NTC can be used as temperature-dependent resistor, which lowers its resistance at an excessively high temperature, so that the voltage at the fourth connection Cfg rises. The controllable current source Icfg can be active, for example, only at the start of the digital control unit IC1, in order to read out the value of the resistor R11, while, in continuous operating mode of the LED module 1, only the voltage resulting across the voltage splitter, comprising the temperature-dependent resistor and resistor R11, is monitored for the detection of an over-temperature.

(60) By way of difference from the examples of FIGS. 9 and 10, in this variant of FIG. 11, the switch is embodied not as an integrated switch element S6 but as an external switch 6 analogous to the example from FIG. 1. This switch 6 is controlled via a fifth connection Sdrv by the digital control unit IC1. A resistor R6 is arranged in series with the switch 6. The current through the resistor R6 can be registered and monitored by the digital control unit IC1 on the basis of the voltage declining across the resistor R6 by means of a sixth connection Imon.

(61) The example of FIG. 12 shows a further embodiment of the digital control unit IC1. This example, like the example of FIG. 10, comprises the connections Vp, Vn and Vdd. The fourth connection Cfg is also present, to which, once again, a resistor R11 (Riled) is connected as configuration element. Furthermore, the digital control unit IC1 comprises two further connections. At one further connection Vovt, a resistor Rovt is connected, which is a temperature-dependent resistor. By monitoring the resistance value of this resistor Rovt, an over-temperature can be detected. Accordingly, a further controllable current source can be arranged in the digital control unit IC1, which flows into the resistor Rovt. Dependent upon the current resistance value, which is monitored on the basis of the voltage registered at this connection Vovt, the digital control unit IC1 can infer an over-temperature on the LED module 1. In analogous manner, via a further controllable current source at the further connection Vitm, a current can be fed into the temperature-dependent resistor Ritm connected to the latter, and the digital control unit IC1 can infer the operating temperature on the LED module 1 from the current resistance value, which is monitored on the basis of the voltage registered at this connection Vitm. Dependent upon the value of the operating temperature registered, the latter can be communicated as information exactly in the same manner as an over-temperature can be communicated to the LED converter as information according to the at least one protocol. The information about the operating temperature can be evaluated by the LED converter, wherein an intelligent feedback control of the current through the LED module 1 can take place, without an over-temperature having to be reached.

(62) The switch 6 or respectively the switch element S6 can perform further functions on the LED module 1, which can be controlled by the digital control unit IC1. For example, an after-glow protection can be allowed. For example, the digital control unit IC1 can detect when the LED module 1 is to be switched off or has already been switched off through the disconnection of the supply voltage. In order to avoid voltages coupled in through parasitic effects or remaining residual charges, the switch 6 or respectively the switch element S6 can be closed in order to avoid a glowing of the LED on the basis of the coupled voltages. Alternatively, or additionally, a protection of the LED module 1 from over-voltages can be achieved, in that, in the case of overvoltage, the switch 6 or respectively the switch element S6 at the supply input of the LED module 1 is at least briefly closed, in order to reduce the overvoltage or respectively protect the LED. In this manner, a protection from over-voltages can be achieved in the case of the separation of the LED module 1 from the LED converter in the operation of the LED module 1, as a so-called hot-plug protection. Such a separation can occur both accidentally through a sudden interruption of contact in the supply line, or also through a user error through an intervention, for example, a change of the LED module 1 during operation.

(63) In a communication mode, the LED converter can cause a change of the LED module through a selective change of the supply voltage for the LED module 1, and the LED converter 10 can then register the change in the power consumption of the LED module 1 and decode it according to the at least one protocol, which is stored, for example, in the LED module 1 and in the LED converter 10. For example, in this manner, the LED converter 10 can request different information from the LED module 1, wherein a specific protocol can be stored for every request. Accordingly, without additional lines or pins, a bidirectional communications path between the LED module and the LED converter is made possible.

(64) The change in the power consumption of the LED module 1 can be caused dependent upon a value of the first supply voltage 5a according to one of several specified protocols and accordingly, a different load change can be caused according to one of several specified protocols.

(65) Three concepts for the registration of the change in power consumption of the LED module 1 through the LED converter 10 are preferred by the present invention. Firstly, the determination of a constant-current load, wherein the constant current can be measured, for example, via a discharge rate of the capacitor in the LED converter 10. Secondly, through determination of a frequency of the change in power consumption of the LED module 1, for example, through direct registration of the current on the converter side. And finally, through indirect registration by means of determining a peak-current within the LED converter, which comprises, for example, an isolated flyback converter or buck converter, which is measured across a shunt. The peak-current follows the change in power consumption of the LED module 1.

(66) In summary, the present invention proposes the communication of information from an LED module 1 to an LED converter 10, which allows an inference to be made regarding operating and/or maintenance parameters to be set in the LED module 1. The operating parameters to be set can be, for example, the set current or the set voltage. For this purpose, a circuit 4 (load-modulation circuit) is provided according to the invention on the LED module, which, for example, within a voltage range of a first supply voltage 5a, which is not equal to zero and at which an LED series 3 connected to the LED module 1 is not conductive, constitutes a load for the LED converter, and, within a voltage range of a second supply voltage 5b, which is not equal to zero and in which a connected LED series 3 is conductive, does not constitute a load for the LED converter 10. The circuit 4 can also be activated only at times, preferably only during a start phase of the LED luminaire. The load can be constant or variable in a repeated manner (modulated), for example, according to a specified protocol.

(67) For instance, a modulated load change can take place, for example, according to a specified protocol. The power consumption can be registered by the LED converter 10, especially also a change in the power consumption (amplitude, frequency, duty factor). As a result, the LED converter 10 can determine the operating and/or maintenance parameters. The communication of this information between the LED module 1 and the LED converter 10 requires no additional connections (only the connection of the supply voltage). Furthermore, no interaction with LED module 1 and/or LED converter 10 is necessary. As a result, the disadvantages of the known prior art are improved.