Color temperature dimming of AC-supplied LED lines using phase information

Abstract

Operating circuit for operating LED lines, comprising - at least two LED sections (5a, 5b) operated in parallel, wherein the LED sections (5a, 5b) are designed to emit light in the white spectrum, wherein the LED sections (5a, 5b) differ from one another with regard to the color temperature of their spectrum, and - a control circuit (SS1, SS2) which can be supplied with an AC voltage and is designed to supply the LED sections (5a, 5b) with a rectified AC supply voltage and with an adjustable total current (I G ), and wherein the control circuit (SS1, SS2) is designed to evaluate the AC voltage and, depending on phase information, such as phase angle or phase section of the AC voltage, to divide the total current (I G ) to the parallel operated LED sections (5a, 5b).

Description

[0001] The invention relates to an operating circuit and a method for operating at least two parallel LED arrays, wherein a color temperature is preferably set based on phase information. The invention also relates to a luminaire or an LED module with such an operating circuit. The phase information is evaluated by a control circuit, which, depending on the evaluation, performs color or color temperature dimming with the at least two parallel LED arrays.

[0002] In the following, dimming or setting a dimming value primarily involves setting or regulating a color temperature, although in principle, the emitted color can also be changed. In addition, brightness dimming can be used to regulate the overall brightness of the light emitted by the LED strips.

[0003] It is known that mixed light of a predetermined color temperature or color can be generated by mixing the light emitted by at least two LED arrays, wherein the light emitted by a first LED array and the light emitted by a second LED array have at least portions of different wavelengths. For example, in an undimmed state, white mixed light can be emitted from the first LED array, which has a higher longer-wavelength portion, while white mixed light can be emitted from the second LED array, which has a higher shorter-wavelength portion. The portion of the respective white mixed light is then adjusted depending on the dimming level. A boundary between longer-wavelength and shorter-wavelength light can be, for example, at 500 nm.

[0004] For example, warm white light can be generated in an LED array by combining at least one red-emitting LED with a color-converted blue- or UV-emitting LED. The UV-emitting LED can, for example, be a blue- or UV-emitting chip covered with a phosphor layer that converts the blue or UV light into longer-wavelength light of a correspondingly different color. Alternatively, white light can also be generated by combining red, green, and blue (RGB) light, each of which can be emitted by at least one LED array with correspondingly colored LEDs.

[0005] For example, the document DE 10 2012 205 349 A1 relates to a circuit arrangement for an LED lamp, with a circuit input for connecting the circuit arrangement to an LED driver for providing an electrical input direct current with a regulated current intensity for operating the circuit arrangement, with at least two LED circuit branches, each comprising at least one LED, wherein the at least two LED circuit branches differ from one another in the coloration and / or the color temperature of at least one LED, and with switching means for controlling a current flow through the at least two LED circuit branches, and wherein the switching means are designed to detect an operating variable for controlling the current flow at at least one of the LED circuit branches and to control the current flow through the at least two LED circuit branches as a control variable depending on the detected operating variable.

[0006] WO 2013 / 110 052 A1 discloses solid-state lighting systems that provide uniform brightness for series-connected LEDs. The corresponding LEDs can be powered directly from the mains, eliminating the need for a switching power supply or the associated output storage elements. In some cases, a linear regulator and switches can be used to control the current through the LEDs and achieve uniform brightness. Other embodiments can be used with a switchable driver topology and / or storage elements connected in parallel with the LED clusters. In each of these cases, control logic (e.g., a microcontroller or other suitable controller) can be used to control the switches accordingly to achieve uniform brightness and, in some cases, mitigate the effects of the lack of an SMPS output storage element.

[0007] Furthermore, the document AT 14 043 U1 provides a dimmable LED lighting system with at least two LED lighting chains connected in parallel and / or in opposite parallel, each having at least one light-emitting diode, wherein the LED lighting system has a control unit and is fed via a supply which is designed to receive dimming information via the supply and to switch individual ones of the parallel / in opposite parallel connected LED lighting chains on and / or off in stages depending on the dimming information supplied and for the implementation thereof.

[0008] Furthermore, the document DE 20 2014 102 296 U1 describes an alternating current (AC) LED (light-emitting diode) device with adjustable light properties, the color temperature of which is lowered when its brightness is reduced.The AC-powered LED device with adjustable light characteristics comprises: an AC power source for providing an AC voltage, a bridge rectifier electrically connected to the AC power source for rectifying the AC voltage and outputting a rectified AC voltage, a plurality of current loops, each of the current loops electrically connected to the AC power source, and a plurality of LED segments, each of the LED segments electrically connected to each current loop, wherein each LED segment connected to a single current loop is turned on in sequence as the AC voltage increases, thereby blending the color temperatures of each LED segment in sequence, wherein each LED segment connected to a single current loop is turned off in reverse order as the AC voltage decreases.

[0009] Furthermore, WO 2013 / 092 843 A1 discloses an operating circuit for an LED path with at least one LED of a first type and an auxiliary LED path with at least one LED of a second type, which is designed to be supplied preferably by a first current source with an adjustable, preferably regulated total current. A main current through the LED path is supplied directly by the total current. The operating circuit comprises a second current source, which is supplied by the total current and supplies the auxiliary LED path with an auxiliary current. The operating circuit further comprises a control circuit that controls the second current source as a function of a voltage across the LED path.

[0010] Furthermore, EP 2 624 664 A1 discloses an LED lighting device connected to a power source via two electrical lines, comprising a first and a second LED having a different emission spectrum or a different chromaticity, a switching unit for monitoring a length of the ON time of the current supplied by the two electrical lines at regular intervals in order to switch a control mode of the first and the second LED between a first mode and a second mode when a state in which the ON time does not change continues to be above a threshold value, a first control unit for determining, in the first operating mode, a total amount of an average current to be supplied to the first LED and an average current to be supplied to the second LED depending on the length of the ON time of the electrical power, and a second control unit,to determine, in the second operating mode, a ratio of an average current to be supplied to the first LED and an average current to be supplied to the second LED as a function of the length of the ON time.,

[0011] Furthermore, document EP 2 760 254 A1 provides an LED lighting system, such as a dimmable LED lamp that can simulate the output of an incandescent bulb. LED strings of different colors are connected to the output of a single LED driver, which controls the overall intensity of the light produced by the LED lighting system. The color of the LED lighting system is controlled by a circuit, such as one or more switches, that allocates current between the LED strings to change the color temperature of the light emitted by the LED lighting system as the light intensity changes.

[0012] Furthermore, US 2013 / 0 063 035 A1 describes electronic circuits for color mixing in an LED luminaire during dimming with alternating current to achieve an adjustable color temperature. According to one embodiment, a dimmable LED luminaire has a first, a second, and a third LED light source, wherein the first and second LED light sources generate white light, the third LED light source generates colored light, the LED driver is configured to power the LED light sources by providing a single-channel variable DC power source with two output terminals, and a current regulator to maintain the current in the third LED light source path substantially constant when the output current of the LED driver is reduced when the AC power is reduced by the dimmer module, thereby changing the color of the light generated by the combination of the LED light sources.

[0013] In the present invention, it is assumed that the at least two LED paths differ from each other with regard to the color temperature of the emitted spectrum.

[0014] The first LED section of the at least two LED sections can emit white light of a first temperature, e.g. warm white (“warm white”, ww) light, while the second LED section of the at least two LED sections emits white light of a second temperature, e.g. cold white (“cold white”, cw) light.

[0015] With conventional incandescent bulbs, users are accustomed to perceiving a change in color temperature—that is, the spectral distribution of the emitted light—when dimming. With incandescent bulbs, increasing dimming levels typically also result in a shift toward a warmer, whiter light. It is also known that LED light sources, which are more energy efficient, can be used instead of incandescent bulbs, and that a phase control can encode dimming information to dim the brightness of LEDs according to dimming information defined by the phase control.

[0016] It is also known to operate LEDs from an AC voltage. A suitable circuit therefore has a rectifier that generates a rectified AC voltage from the AC voltage, which is then fed to the LEDs. The LED paths also each have at least one switching element that bridges at least one LED in the respective LED path. Depending on the curve of the rectified AC voltage or the amplitude value or amplitude swing of the rectified AC voltage, LEDs in the LED paths are switched on or off, i.e. activated or deactivated. In particular, when the amplitude of the rectified AC voltage increases, LEDs can be switched on, while when the amplitude of the rectified AC voltage decreases, LEDs can be switched off or the LEDs can be bridged. This operating principle is also referred to as “AC-LED”.

[0017] The invention now further develops the idea by evaluating phase information, for example, a phase leading edge or a phase trailing edge, with respect to color temperature dimming, i.e., as information that defines a desired color temperature or a color locus to be set. In particular, the phase information can be used to determine a setting for white mixed light.

[0018] The control circuit is capable of controlling the at least two parallel LED paths, on the one hand according to the AC LED principle described above, in which the load follows the rectified AC voltage step by step, and on the other hand according to a mixing ratio that is set depending on the color temperature specification defined by the phase information.

[0019] The invention therefore provides an operating circuit and a method according to the independent claims. Further developments of the invention are the subject of the dependent claims.

[0020] In a first aspect, an operating circuit for operating LED sections is provided, comprising at least two LED sections operated in parallel, wherein the LED sections are designed to emit light in the white spectrum, wherein the LED sections differ from one another with regard to the color temperature of their spectrum, and a control circuit which can be supplied with an AC voltage and is designed to control the supply of the LED sections with a rectified AC supply voltage and with an adjustable total current, and wherein the control circuit is configured to evaluate the AC voltage and to set a distribution of the total current between the LED sections operated in parallel depending on phase information, such as, for example, phase control or phase cut-off of the AC voltage.

[0021] The control circuit can distribute the total current between the at least two parallel LED paths simultaneously or alternately.

[0022] The control circuit can control at least two adjustable current sources based on the evaluation of the phase information and determine the distribution of the total current between the at least two parallel LED paths. The at least two adjustable current sources are preferably part of the operating circuit.

[0023] An adjustable current source can be assigned to at least one LED strip. The LED strips can also be powered from a common adjustable current source. The current sources can be constant current sources.

[0024] The operating circuit can have an adjustment circuit. The control circuit can control the adjustment circuit. In particular, the control circuit can variably adjust the switch-on time of the two different LED sections by varying duty cycles.

[0025] The control circuit can adjust the distribution of the total current between the parallel LED paths.

[0026] The control circuit can output a control signal to the control circuit. The control circuit can adjust the switch-on time of the at least two different LED strings in a variable, and in particular alternating, manner depending on the control signal.

[0027] The control circuit can output the control signal with different duty cycles. The control circuit can adjust the switch-on time of the at least two parallel LED paths depending on the duty cycles.

[0028] Each of the at least two parallel LED paths can have one or more LEDs and one or more switching elements. At least one of the LEDs in each LED path can be bridged by a switching element controlled by the control circuit.

[0029] The control circuit can detect a waveform of the rectified supply voltage and, depending on this, selectively activate and / or deactivate the switching elements.

[0030] Each LED strip can only contain LEDs of one type.

[0031] At least one LED track may comprise LEDs of different types, in particular LEDs that emit light of different color temperatures.

[0032] In a further aspect, a luminaire or an LED module is provided with an operating circuit as described above.

[0033] In yet another aspect, a method for operating LED paths is provided, wherein at least two LED paths operated in parallel emit light in the white spectrum and differ from one another with regard to the color temperature of their spectrum, and wherein a control circuit that can be supplied with an AC voltage controls the supply of the LED paths with a rectified AC supply voltage and with an adjustable total current, and wherein the control circuit evaluates the AC voltage and, depending on phase information, such as phase control or phase cut-off of the AC voltage, sets a distribution of the total current between the LED paths operated in parallel.

[0034] The invention will now be described with reference to the figures. They show: Fig. 1 schematically shows a first example of an operating circuit; Fig. 2 schematically shows another example of an operating circuit; Fig. Figure 3 shows schematically an operating circuit which represents a starting point of the invention; Fig. 4 schematically shows an embodiment of an operating circuit according to the invention; and Fig. 5 schematically shows a further embodiment of an operating circuit according to the invention.

[0035] First, based on the Fig. 1 and Fig. 2 a possible circuit design of an operating circuit and a basic mode of operation will be explained. A more detailed embodiment of the invention will then be explained, particularly with regard to the Fig. 4 and Fig. 5. Technically identical elements are, in particular, referred to as identically as far as possible.

[0036] For example, to create an LED lamp that emits a "warmer" light with increasing dimming or that allows for the adjustment of a color coordinate, an LED array with a first spectral characteristic is operated in parallel with another LED array with a different spectral characteristic. In particular, the LED arrays differ from one another in terms of the color temperature of their spectrum.

[0037] For example, one LED array may contain only one type of LED, while the second LED array may use a different type of LED. The first LED array may emit cold white (CW) light, while the second LED array may emit warm white (WW) light.

[0038] However, it is also possible for one LED section to emit white light and the other, for example, amber light. Of course, instead of white-light emitting LED sections, colored LED sections can also be used (e.g., red, yellow, blue, and / or green LEDs). The LED sections can also contain different types of LEDs, for example, to set a specific tint or create a specific color impression. For example, one or more yellow, red, or other colored LEDs can be used together with white LEDs.

[0039] It is also possible to connect white LEDs with different color temperatures in series in an LED array, and then achieve mixing by selectively activating / deactivating the different white LEDs, while, as mentioned, still maintaining the AC LED operating principle. For this purpose, the switching elements are switched on / off by the control circuit.

[0040] Fig. Figure 1 now shows a schematic block diagram of an operating circuit. A rectifier module 20 is supplied with an alternating voltage 10. The rectifier module 20 generates a rectified alternating voltage 11. The rectified alternating voltage 11 then supplies a current source 21, in particular a direct current source, which is preferably designed as a direct current converter. The direct current converter can be implemented as an isolating flyback converter. The direct current source then generates a total current I G, which is supplied to the at least two LED sections 22. An LED section is understood here to mean that the LED section has at least one LED, but preferably several LEDs connected in series. The current source 21 can also be combined with the rectifier module 20 in a single or individual module. A dimming device 24 generates a dimming signal 15a, which is supplied to the operating circuit. The current source can control the total current I G depending on the dimming signal 15a.

[0041] Thus, the signal 15a can cause the first current source 21 to supply a constant direct current I Gan adjustable current intensity to operate the light source 22. The dimming device 24 preferably determines that the signal 15a is determined as a function of a dimming value, which is set, for example, by a user on a dimmer. In particular, a leading edge or trailing edge phase control, which is frequently generated by leading edge or trailing edge dimmers, can be evaluated as the dimming signal. The AC voltage supplied to the rectifier 20 then accordingly has a leading edge and / or trailing edge phase control, which is also present in the rectified AC voltage after rectification by the rectifier 20.

[0042] In Fig. 2 shows another example. The structure is largely the same as in Fig. 1. In addition, the circuit here includes a control circuit 23, which processes a signal 13 that allows conclusions to be drawn about the current color temperature of the light generated by the at least two parallel LED sections or the light source 22. Here, a dimming signal 15b is fed to the control circuit 23. The control circuit 23 can generate a control signal for controlling the LED sections from the dimming signal 15b and / or the signal 13. In addition to the dimming signal 15b and the signal 13, further signals from the control circuit 23 can be provided for controlling the LED sections 22. For example, it is conceivable that an additional temperature signal is processed. Since the LEDs have a temperature characteristic, it is helpful to take the current temperature into account when controlling the LEDs. The use of a temperature signal is particularly advantageous for keeping the color temperature constant at a specific dimming value.LEDs of different types, and thus different wavelengths, often exhibit different temperature characteristics. This means that when the temperature changes, the mixture of the light from the light source 22 is adjusted by the control unit 23.

[0043] Dimming in the Fig. 1 and Fig. 2 can refer to brightness dimming and / or color temperature dimming.

[0044] Fig. 3 now shows an operating circuit that represents the starting point of the present invention. Starting from input terminals E1, E2, an alternating voltage AC is supplied to the rectifier module 20, which is converted by the rectifier module 20 into a rectified alternating voltage. A control circuit SS evaluates the rectified alternating voltage. For this purpose, the control circuit SS can have an adaptive detection circuit 1 and an evaluation circuit 2. Depending on the rectified AC voltage, the control circuit SS controls switching elements S1, S2, S3, which are configured to selectively bridge exemplary LEDs L1, L2, L3 of an LED path 5. For bridging, the switching elements S1, S2, S3 are switched on / activated. Of course, the circuit can have fewer or significantly more switching elements and LEDs.The switching elements are opened or closed depending on the instantaneous value of the voltage amplitude of the rectified AC voltage in order to guarantee a predetermined operating point of the load (AC LED).

[0045] A current I through the LEDs L1, L2, L3 is regulated by a current source 4, which is controlled by the control circuit SS. The control circuit SS can thus dim the LEDs by changing the amplitude of the current I provided by the current source 4. Fig. 3 Consequently, the current I is only supplied to the LED circuit 5 with the serial LEDs L1, L2 and L3.

[0046] Fig. 4 shows an operating circuit based on the operating circuit of Fig. 3, but has two parallel LED paths 5a, 5b. The two LED paths 5a, 5b are also shown here with 3 LEDs L1a, L2a, L3a and L1b, L2b, L3b respectively. Also shown are corresponding switching elements S1a, S2a, S3a and S1b, S2b, S3b, respectively, which can selectively bridge the LEDs of the LED paths 5a, 5b. Again, it should be understood that more or fewer LEDs and switching elements can be provided per LED path 5a, 5b. Furthermore, one switching element can selectively bridge multiple LEDs. Transistors (bipolar, FET, MOSFET) can be used as switching elements.

[0047] Also shown is a control circuit SS1, which in turn has an adaptive detection circuit 1 and an evaluation circuit 2. The adaptive detection circuit 1 detects phase information of the rectified AC voltage, i.e., in particular, the phase leading and / or trailing edge duration. The phase information can also be detected from the supplied AC voltage itself. The phase information is then evaluated by an evaluation circuit 2. Furthermore, the control circuit SS1 controls two controllable current sources 4a and 4b depending on the phase information. In particular, one of the current sources 4a and 4b is provided for each of the at least two LED sections 5a, 5b. Several LED sections can also be assigned to one current source. Thus, the control circuit SS1 can set a current through each of the two LED sections 5a, 5b separately. A total current I supplied to the two LED sections 5a, 5b Gis thus distributed to the LED sections 5a, 5b. The first current source 4a regulates, depending on the control by the control circuit SS1, e.g. a current I ww through the first LED section 5a. The second current source 4b regulates, depending on the control by the control circuit SS1, e.g. a current I cw through the second LED section 5b.

[0048] For example, if only warm-white LEDs are provided in the first LED section 5a and only cold-white LEDs are provided in the second LED section 5b, a white mixed light can be generated by controlling the current sources 4a and 4b, which lies between the color temperature point of the first LED section 5a and the color temperature point of the second LED section 5b.

[0049] Also indicated is an input of the control circuit SS1, via which information can be supplied to the control circuit SS1 from an input circuit 6. The input circuit 6 represents a possibility for supplying further inputs to the control circuit SS1. For example, a potentiometer can be provided that explicitly specifies a setting of the color temperature value or an additional brightness dimming value. A fuse and / or a resistor can also be connected to the control circuit SS1, which, depending on their fuse or resistance value, define a color temperature value to be set. In this way, a color temperature value can be set at the time of production by connecting a resistor or fuse to the evaluation circuit. Other signals that specify a color temperature can also be supplied to the control circuit via input 6, e.g.Bus signals from a bus, especially DALI bus.

[0050] The control of the switching elements S1a, S2a, S3a or S1b, S2b, S3b by the control circuit SS1 is schematically shown by dashed lines starting from the control circuit SS1 or the evaluation circuit 2.

[0051] What next with regard to Fig. 5, which essentially represents the Fig. 4, it is not absolutely necessary to provide separate power sources for at least one LED track. As shown in Fig. 5, a control circuit 7 can also be provided in series with the at least two LED sections 5a, 5b.

[0052] The Fig. 5 again shows only a single current source 4'. A control circuit 7 now regulates the degree to which the at least two LED sections 5a, 5b are controlled, or how a total current I Gis divided into the LED sections 5a, 5b. The LEDs and switching elements of the LED sections essentially correspond to those of Fig. 4 and are not separately labeled. The control circuit 7 can control the distribution of the total current I G to at least two LED sections 5a, 5b.

[0053] In particular, for example, a control circuit SS2, which essentially corresponds to the control circuit SS1, can output a signal to the control circuit 7, which determines the division of the total current I GThis signal can, for example, be a pulse-width modulated square wave signal (PWM signal). This signal has an essentially constant period and oscillates between two different voltage levels. In principle, the signal is therefore switched on and off in rapid succession. The ratio of switch-on time to switch-off time can vary and can be set by the control circuit SS2. This ratio is referred to as the duty cycle. For example, by specifying the duty cycle via the control circuit SS2 and via the signal fed to the control circuit 7, a color temperature for the LED sections 5a, 5b can be set. The switch-off time can specify the dimming level for one LED section 5a, while the switch-on time specifies the dimming level for the other LED section 5b.

[0054] However, the LED sections can also be operated alternately according to the duty cycle. Thus, the control circuit SS2 can control the control circuit 7 with the signal and thus define the duration for which the at least two LED sections 5a, 5b are to be switched on. In particular, for example, the on-time duration of the PWM signal can specify the on-time duration of a first LED section 5a, and the off-time duration can specify the on-time duration of the second LED section 5b. A high signal frequency (preferably 100 Hz or higher) can prevent a flickering effect.

[0055] In particular, the control circuit 7 divides the total current I G dynamically on the at least two LED lines in the currents I cw and I ww Again, by adjusting the current amplitude of the current source 4', the total current I G controlled.

[0056] The control circuit SS1, SS2 can therefore be Fig. 4 and Fig. 5 on the one hand, the color temperature by dividing the total current I G to the LED sections 5a, 5b, in the range between the color temperatures of at least two LEDs. In addition, by regulating the total current I G brightness dimming can occur.

Claims

[1] Operating circuit for operating LED lines, comprising - at least two LED sections (5a, 5b) operated in parallel, wherein the LED sections (5a, 5b) are designed to emit light in the white spectrum, wherein the LED sections (5a, 5b) differ from one another with regard to the color temperature of their spectrum, and - a control circuit (SS1, SS2) which can be supplied with an AC voltage and is designed to supply the LED sections (5a, 5b) with a rectified AC supply voltage and with an adjustable total current (I G ), and wherein the control circuit (SS1, SS2) is designed to evaluate the AC voltage and, depending on phase information, such as phase angle or phase section of the AC voltage, to divide the total current (I G ) to the parallel operated LED sections (5a, 5b). [2] Operating circuit according to claim 1, wherein the control circuit (SS1, SS2) is arranged to control the division of the total current (I G ) on the at least two parallel LED sections (5a, 5b) simultaneously or alternately. [3] Operating circuit according to claim 1 or 2, wherein the control circuit (SS1, SS2) controls at least two adjustable current sources (4a, 4b) depending on the evaluation of the phase information and the division of the total current (I G ) to the at least two parallel LED sections (5a, 5b) for each of the at least two parallel LED sections (5a, 5b). [4] Operating circuit according to claim 3, wherein a current source (4a, 4b, 4') is arranged in series with at least one LED section (5a, 5b). [5] Operating circuit according to one of the preceding claims, wherein an adjustable current source (4a, 4b, 4') is assigned to at least one LED section (5a, 5b). [6] Operating circuit according to one of the preceding claims, wherein the operating circuit has an actuating circuit (7), wherein the control circuit (SS1, SS2) is arranged to control the actuating circuit (7). [7] Operating circuit according to claim 6, wherein the control circuit (7) is arranged to control the division of the total current (I G ) to the parallel LED sections (5a, 5b). [8] Operating circuit according to claim 6 or 7, wherein the control circuit (SS1, SS2) is configured to output a control signal to the control circuit (7), and wherein the control circuit (7) is configured to set a switch-on time of the at least two different LED sections (5a, 5b) in a variable manner, and in particular alternately, depending thereon. [9] Operating circuit according to one of claims 6 to 8, wherein the control circuit (SS1, SS2) is configured to output the control signal with different duty cycles, and wherein the setting circuit (7) is configured to variably set the switch-on time of the at least two parallel LED paths (5a, 5b) depending on the duty cycles. [10] Operating circuit according to one of the preceding claims, wherein each of the at least two parallel LED paths (5a, 5b) has one or more LEDs (L1a, L2a, L3a, L1b, L2b, L3b) and one or more switching elements (S1a, S2a, S3a, S1b, S2b, S3b), and wherein at least one of the LEDs (L1a, L2a, L3a, L1b, L2b, L3b) of an LED path (5a, 5b) can be bridged by a switching element (S1a, S2a, S3a, S1b, S2b, S3b) controlled by the control circuit (SS1, SS2). [11] Operating circuit according to one of the preceding claims, wherein the control circuit (SS1, SS2) is configured to detect a profile of the rectified supply voltage and, depending thereon, to selectively activate and / or deactivate the switching elements (S1a, S2a, S3a, S1b, S2b, S3b). [12] Operating circuit according to one of the preceding claims, wherein each LED section (5a, 5b) has only LEDs of one type. [13] Operating circuit according to one of claims 1 to 11, wherein at least one LED section (5a, 5b) comprises LEDs of different types, in particular LEDs which emit light of different color temperatures. [14] Luminaire or LED module with an operating circuit according to one of the preceding claims. [15] Method for operating LED lines, wherein - at least two parallel-operated LED lines (5a, 5b) emit light in the white spectrum and differ from each other with regard to the color temperature of their spectrum, and wherein - a control circuit (SS1, SS2) which can be supplied with an AC voltage, supplies the LED sections (5a, 5b) with a rectified AC supply voltage and with an adjustable total current (I G ), and wherein the control circuit (SS1, SS2) evaluates the AC voltage and, depending on phase information, such as phase angle or phase section of the AC voltage, divides the total current (I G ) to the parallel operated LED lines.

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