EP2796003A1

EP2796003A1 - Method and circuit arrangement for dimmable generation of light by means of leds, with colour temperature control

Info

Publication number: EP2796003A1
Application number: EP12815674.2A
Authority: EP
Inventors: Philip JERMYN
Original assignee: Tridonic GmbH and Co KG
Current assignee: Tridonic GmbH and Co KG
Priority date: 2011-12-23
Filing date: 2012-12-20
Publication date: 2014-10-29
Anticipated expiration: 2032-12-20
Also published as: EP2796003B1; DE112012005371A5; WO2013092843A1

Abstract

An operating circuit for an LED series (30) with at least one LED (31-39) of a first type (w) and an auxiliary LED series (70) with at least one LED (63) of a second type (a) is designed to be preferably supplied by a first current source with an adjustable, preferably regulated, overall current (I_G). A main current (I₁) through the LED series (30) is directly supplied by the overall current (I_G). The operating circuit also has a second current source (60), which is supplied by the overall current (IG) and supplies an auxiliary current (I₂) to the auxiliary LED series (70). The operating circuit further has a control circuit (40), which controls the second current source (60) on the basis of a voltage (U_G) on the LED series (30).

Description

METHOD AND CIRCUIT ARRANGEMENT FOR DIMMABLE LIGHT GENERATION BY LEDS, WITH COLOR TEMPERATURE CONTROL

5

The invention relates to a method and a

Circuit arrangement for the dimmable generation of light. In an undimmed state, the light is converted by mixing longer-wavelength light of at least a first LED and

10 shorter-wavelength light generates at least a second LED.

With increasing dimming, the proportion of shorter-wave light is reduced. In a maximum dimmed state, the resulting light consists only of light from the first LED. The border between the longer-wave and the

15 shorter-wavelength light may, for example, be at 500 nm (with respect to the peak of the spectrum).

It is known to mix light of a predetermined color by mixing the light emitted from at least two LEDs

Produce 20, the one of the LED and that of the

other LED light emitted have different wavelengths. For example, intestine ¹ can pass through white light

Mixing the light emitted by a red light LED and that of a color-converted blue light LED or UV light

25 light LED (this is, for example, a blue light or UV light-emitting LED chip, which is covered with a phosphor layer, which converts the blue light or the UV light into a longer-wave light with a correspondingly different color , be generated.

Alternatively, white light can be generated by RGB (red, green, blue) mix or other mixes.

Thus, e.g. International Patent Application WO

2001/054547 AI an LED drive circuit, which a passive compensation branch, which reduces the voltage at one or more LEDs to the

Adjust color temperature. However, part of the electric power is thermally converted resulting in high energy consumption.

Conventional incandescent lamps have accustomed users to a change in color temperature when dimming, i. of the

spectral distribution of the emitted light. With incandescent lamps, a shift towards warmer light usually results with increasing degree of dimming.

However, conventional incandescent lamps have a very low energy efficiency. The invention has for its object to provide a method and a circuit arrangement which a replica of the change in color temperature in a dimming of a conventional light bulb with the least possible effort and at the same time as high

Enable efficiency.

The task is characterized by the characteristics of the independent

Claims solved. The dependent claims form the central idea of the invention in particular

advantageously continue.

An operating circuit according to the invention for an LED track with at least one LED of a first type and an auxiliary LED track with at least one LED of a second type is designed to be preferably from a first

Power source to be supplied with an adjustable, preferably regulated total current. A main current through the LED track is powered directly from the total current. The operating circuit has a second current source, which is powered by the total current and supplies the auxiliary LED track with an auxiliary current. The

Operating circuit further comprises a control circuit which controls the second current source in response to a voltage at the LED track. So can one

Color change can be realized during dimming without unstable operating conditions occur. The second current source is preferably designed as a high-frequency clocked current source, in particular as a high-frequency clocked switching regulator. By using a

High frequency clocked power source allows the energy to be cached and stored only

different branches is distributed, but no energy is converted into thermal energy here.

The control circuit is preferably designed to control, when a threshold value is exceeded by the voltage, the second current source in order to supply the auxiliary LED path with the auxiliary current and, when the voltage drops below the threshold value, the second one

To control power source, so as not to supply the auxiliary LED track with the auxiliary power. Preferred is a

Tension voltage of the LED track is greater than the

Threshold. This allows unstable operating states

especially safe to avoid.

The second power source is preferably such

designed such that at an amplitude dimming of the

Total current, the auxiliary current through the auxiliary LED track is constant, and so the auxiliary LED track constantly emits light, as long as the LED track a main current

absorbs and thus emits light. The auxiliary current through the auxiliary LED path is subject to an amplitude dimming, so that the auxiliary LED route emits dimmed light, as long as the LED Streckek receives a main current and so emits no light. Unstable operating states can thus be safely avoided in the case of amplitude modulation. The second current source is preferably designed such that, when dimming by means of pulse width modulation of the total current, the auxiliary current through the auxiliary LED path follows the course of the total current and the auxiliary LED path emits light in a dimmed manner. Thus, an afterglow of the auxiliary LED route can be avoided in a pulse width modulation operation.

The second current source is alternatively designed such that when dimming by means of pulse width modulation of the total current, the auxiliary current through the auxiliary LED path has no pulse width modulation and the auxiliary LED route emits light so constant and undimmed. This ensures that in a pure pulse width modulation operation, a color change occurs during dimming.

The control circuit preferably includes a

Comparator that compares the voltage at least indirectly with the threshold. The control circuit is designed to transmit a control signal to the second current source as a function of the comparison. The second current source is preferably designed to be in

Dependence of the control signal to supply the auxiliary LED track with the auxiliary power. The control circuit preferably has a switch, preferably a transistor, which generates the control signal as a function of the comparison. So can with simple circuit engineering

Means the desired behavior of the operating circuit can be achieved. The comparator preferably has a voltage divider and a voltage reference. The voltage divider then reduces the voltage by a factor. The voltage reference preferably generates a reference voltage which corresponds to the threshold value reduced by the factor. Of the

The comparator preferably compares the lowered operating voltage with the constant voltage of the

Voltage reference. So can with simple

circuit means the desired behavior of the operating circuit can be achieved.

An LED module according to the invention comprises at least one operating circuit described above and an LED track with at least one LED of a first type and an auxiliary LED track with at least one LED of a second type. The LEDs of the first type and the LEDs of the second type preferably have different

Emission spectra on. So it is possible to achieve a desired color temperature depending on the degree of dimming.

An LED lamp according to the invention is preferably a

Retrofit LED light with at least one previously

described LED module and a first power source. So conventional lights can be easily replaced.

An inventive method is used to operate an LED track with at least one LED of a first type and an auxiliary LED track with at least one LED of a second type. The LED track and the auxiliary LED track are controlled by an adjustable, preferably regulated

Supplied total current. A main current through the LED track is powered directly from the total current. The auxiliary LED section is supplied with an auxiliary current. The auxiliary current is dependent on a voltage at the LED track controlled. Unstable operating conditions can be so at a

Amplitude modulation can be safely avoided.

Further features, advantages and characteristics of the invention will now be explained with reference to the figures of the accompanying drawings. Show it:

Fig. 1 shows a first embodiment of a

lamp according to the invention;

Fig. 2 shows a second embodiment of a

lamp according to the invention;

Fig. 3 shows a first embodiment of a

LED module according to the invention, and

Fig. 4 shows an embodiment of the invention

Procedure. First, the structure and operation of different embodiments of the device according to the invention will be explained with reference to FIGS. 1-3. Subsequently, with reference to FIG. 4 in detail the operation of a

Embodiment of the inventive method shown. Identical elements were similar

Illustrations partly not shown and described repeatedly.

In order to create an LED lamp which emits a warmer ¹ light with increasing dimming, it is provided that at least one white LED should use an amber LED. The use of one or more yellow red or RGB LEDs is also conceivable. The current one

Invention is based on the underlying idea that colored LED or the colored LEDs at constant

Brightness while the dimming process only affects the white or white LEDs. Optional can

in addition, after dimming the white LED, insert a dimming of the colored LED.

Usually, a dimming of an LED light is achieved by an amplitude modulation and / or a pulse width modulation of an operating current. In the case of one

Amplitude modulation of the operating current, it is thus an object of the present invention, the operating current of

color LED is kept constant, while the operating current of the white LED or LEDs is reduced depending on the Dimmgrads.

In the case of pulse width modulation, it is optional goal of the present invention, a permanent operation of the colored LED as independent as possible

Pulse width modulation to achieve. That the white LED or the white LEDs are thus pulse-width modulated, while the colored LED as possible undergoes no such modulation.

However, the present invention is not limited to white or red LEDs. It is only important that at least two LED sections are used, each with at least one LED. The emission spectra of the two routes must differ to one

To be able to represent color change when dimming.

Fig. 1 shows a first embodiment of a

LED lamp according to the invention. A rectifier module 20 is supplied with an AC voltage 10. The

Rectifier module 20 generated from the AC voltage 10th a DC voltage 11. The DC voltage 11 supplies a first current source 21. The first current source 21 is a DC source, the

is preferably designed as a DC-DC converter, for example as an isolated flyback converter. It generates a total current I _G , with which an LED module 22

is operated. It may also include the rectifier module 20 and the first current source 21 in a single module

be integrated.

A dimming device 24 generates a dimming signal 15a, which is supplied to the current source 21. The current source 21 generates the current I _G as a function of

Dimming signal 15a.

The following is first of a pure

Amplitude modulation assumed. That the dim signal 15a causes the first current source 21 to be constant

DC I _G generate an adjustable current and thus to operate the LED module 22. The

Dimming device 24 determines the dimming signal 15a in response to a dimming value, which is e.g. of a

User is set on a dimmer. Alternatively, a pulse width modulation can be used. In this case, the dimmer 24 generates the dimming signal 15a as a pulse width modulation signal. That the dimming signal specifies a frequency and a duty cycle of the pulse width modulation by the first current source 21.

On the exact structure and operation of the LED module 22 will be discussed in detail with reference to FIG. 3. In Fig. 2 is a second embodiment of

LED lamp according to the invention shown. The structure corresponds largely to the structure of FIG. 1. In addition, the LED light here includes a control device 23, which processes a signal 13, which allows conclusions about the current brightness of the light generated by the LED module 22. Here is one

Dimming signal 15b of the control device 23 is supplied. The control device 23 generates a control signal 14 for controlling the first current source 21 from the dimming signal 15b and the brightness signal 13.

In addition to the dimming signal 15b and the brightness signal 13, further signals can be added to the control by the

Control device 23 are included. For example, e.g.

conceivable to process an additional temperature signal. Since LEDs have a temperature characteristic, it is helpful to consider the current temperature for controlling the LEDs. In particular, to the

To keep the color temperature constant at a certain dimming value, the use of a temperature signal is very advantageous since LEDs of different types and therefore different wavelengths often have different temperature characteristics. That at a

Temperature change, it may be necessary to adjust the mixture of light through the LED module 22.

In the case of a pulse width modulation generates the first

Current source 21 a pulse width modulated current I _G. The pulse width modulation corresponds to the desired

Dimming degree or is determined as shown with reference to FIG. 2, depending on further control parameters. In Fig. 3 is a first embodiment of the

illustrated LED module. An LED module 22 has connections 12a, 12b. It has an LED track 30, a control circuit 40, a power source 60 and an auxiliary LED track 70.

The LED section 30 consists of series-connected LEDs 31-39. The LEDs 31-39 here are white LEDs of a first type w. The LED track30 is with the

Terminals 12a, 12b connected directly and is powered by the total current I _G. It adjusts a main current Ιχ through the LED track 30.

The second current source 60 includes an integrated circuit 67, such as a device of the type

TS19373 as an example of a controller IC for one

Down converter. The integrated circuit 67 is connected via a first terminal 67 ₃ by means of a capacitor 62 to the terminal 12a. The connection 12a here corresponds to the supply current I _G. About one

Terminal 67 ₂ , the integrated circuit 67 is directly connected to ground. It is connected via a connection 67i by means of a coupling capacitor 68 to the connection 12b

connected. The connection 12b here corresponds to ground. Via a connection 67 ₄ , it is connected to a voltage divider 69 consisting of an ohmic resistor 64 and an ohmic resistor 66. Via a connection 67 ₅ , it is furthermore connected to an inductance 65, which in turn is connected to the center of the voltage divider 69. the terminal 67 ₅ is further connected via a diode 61 to the terminal 12 a. The integrated circuit 67 facing away from the end of

Voltage divider 69 is also connected to the auxiliary LED track 70. The auxiliary LED track includes here only one LED 63 of a second type a. On its other side is the LED 63 with the terminal 12a

connected . The second current source 60 corresponds to one here

Down converter as an example of a high frequency clocked switching regulator. From the terminals 12a and 12b, the power source 60 draws so much current to produce a constant current. The LED section 70 is supplied with this current. This results in a negative

Current-voltage characteristic of the constant current source 60. D.h. with increasing operating voltage of the drops

extracted electricity.

The integrated circuit 67 determines the voltage drop across the resistor 64 via the voltage divider 69. The voltage drop is determined between the terminal 67 i and the terminal 67 ₄ . The integrated circuit 67 adjusts the current through the auxiliary LED path 70 such that the voltage drop always has a fixed value,

for example, assumes 0.3 volts. The current can thus be adjusted by selecting the resistor 64.

Otherwise it is a constant current. The integrated circuit 67 stores energy in the inductance 65. The energy stored in the inductance 65 is used to generate the constant current as an output signal.

If a continuous current I _{G is applied} to the LED module 22 (as in the case of amplitude modulation), a constant amount of energy is always present in the inductance 65

saved. The production of a constant

Output current is thus unproblematic for the constant current source 60. However, there is an alternating voltage (such as in a pulse width modulation) to the

Terminals 12a, 12b, the energy stored in the inductor 65 changes over time. As long as a voltage is applied between the terminals 12a, 12b, the energy stored in the inductance 65 increases or remains constant at its maximum value. As long as no voltage is applied to the terminals 12a, 12b, the energy stored in the inductance 65 decreases, while the constant current source 60 continues to generate a constant current as an output signal and the LED 63 supplies. The inductance 65 is designed so small that the LED module 22 according to the invention meets the special property of the color change in the course of dimming only with an amplitude modulation. That the energy in the inductance is not enough to one

Off period of a pulse width modulation to

bridged. An afterglow during the off periods of a pulse width modulation can be avoided.

Alternatively, the inductance 65 is designed such that the operating current for the LED 63 is sufficient even with a minimum duty cycle of the pulse width modulation in order to permanently supply the LED 63 with a constant current. In this case, the

Color change when dimming even with a pure

Pulse width modulation can be maintained.

Without further action there are operating conditions in which the constant current source 60 is unstable. Thus, the input of the current source 60 acts as a load

negative resistance. That is, the supply voltage increases while the operating current decreases. This combination is not stable, as is a Feedback mechanism with the power source 21

developed. Trying to increase the current will actually reduce it. This combination works stably while the LED

Route30 is in operation. The voltage U _G is kept at a fixed value by the LED path 30 in this case. This provides a source of low impedance for the current source 60. Thus, problems only arise while the LED track 30 is nonconductive. This is at power up, at power off and at a

Pulse width modulation of the case.

During power up, or at the rising edge of each pulse width modulation pulse, the current source 21 must ramp up its output voltage until the LED trace 30 becomes conductive. If the power source 60 is connected, so a very large current is drawn, resulting in a

Collapse of the supply voltage U _G leads. A drop in the supply voltage U _G in turn ensures a

Rise of the drawn from the constant current source 60

Electricity.

To overcome these problems, the

Constant current source 60 by means of a control circuit 40 causes to show in terms of their current-voltage characteristic of the behavior of an LED track. That is, the current source 60 is caused, only from a threshold value, a part I _{2 of} the operating current I _G

take. The following will discuss the exact function of the control circuit 40.

The control circuit 40 has a voltage divider 51 consisting of ohmic resistors 41 and 42, which also connected to the terminals 12a and 12b. The center of the voltage divider 51 is connected to a negative input of an operational amplifier 45. In addition, the center of the

Voltage divider 51 via an ohmic resistor 44 to the output of the operational amplifier 45 is connected.

A voltage divider 52 is formed by an ohmic resistor 43 and a Zener diode 46. Of the

Center of this voltage divider 52 is connected to the

positive input of the operational amplifier 45. The operational amplifier 45 thus compares a through the first voltage divider 51 in the ratio of the resistors 41, 42 lowered operating voltage U _G with the breakdown voltage of the Zener diode 46. outweighs the decreased operating voltage U _G, is so the

Operational amplifier 45 at its output a LOW signal. In contrast, outweighs the breakdown voltage of

Zener diode 46, the operational amplifier 45 outputs a HIGH signal at its output. These resulting

Signals are dissipated via a third voltage divider 53 to ground. The voltage divider 53 consists of ohmic resistors 47 and 49. At the midpoint of the voltage divider 53, the signal becomes the base of a

Transistor 48 is supplied. The collector is connected via an ohmic resistor 50 to ground. The emitter of the transistor 48 is connected to the power source 60. The transistor 48 here has the function of a switch. That when the operational amplifier outputs a HIGH signal at its output, the collector-emitter path of the transistor 48 becomes conductive.

The emitter of the transistor 48 is connected to the terminal 67 _{4 of} the integrated circuit 67. Is the Transistor conductive, a voltage drop is at the

Terminal 67 ₄ generated because the current through the transistor 48 via the resistor 66 is pulled. The said voltage drop leads to a shutdown of

Constant current source 60.

That is, as long as the voltage U _{G is} below a threshold value, the current source 60 and thus also the auxiliary LED path 70 is switched off. This allows the

Power source 21, which supplies the LED module 22, can reach a stable operating state before the

Power source 60 is turned on. As soon as the threshold is exceeded by the voltage U _G , the output of the operational amplifier 45 changes to low, the

Transistor 48 becomes nonconductive and an artificial voltage drop at terminal 67 ₄ no longer becomes

generated. The power source 60 thus starts operating. Since there is already a significant current flow Ii through the LED path 30, the negative current-voltage characteristic of the current source 60 can no longer adversely affect the current source 21.

By the value of the ohmic resistors 41, 42 and 44, the amplification factor of the operational amplifier 45 can be set. The amplification factor can be the current-voltage characteristic of the overall circuit

be set. A low gain provides a "soft" threshold, which results in the auxiliary LED link 70 not being switched on instantaneously but slowly when the threshold is exceeded by the voltage U _G. If a pulse width modulation takes place, then the process of turning on and off the constant current source 60 takes place at each individual pulse. In the case of the amplitude modulation of the operating current I _G , the process mentioned only once at

Switching on and off when switching off.

Alternatively, it is also conceivable that the integrated

Circuit 67 has its own pulse width modulation of

Duty cycle of the auxiliary LED track 70 performs. In this case, the integrated circuit 67 is informed of the dimming value of the auxiliary LED path 70 via an additional signal. The pulse width modulation of the auxiliary LED path 70 is completely independent in this case

Pulse width modulation by the current source 21 and of the amplitude modulation by the current source 21st

Within the second power source 60 may also be

Buffer capacitor be arranged as energy storage.

This can, for example, in the operating phase in which the auxiliary LED path 70 is supplied with the auxiliary current I ₂ , an energy buffering. Within this phase, this energy is taken from the LED track 30. In a further phase, the buffered energy of the buffer capacitor can be released again.

For example, this energy may then be used in a further phase of the operation of the auxiliary LED track 70 to power the auxiliary LED track 70.

In Fig. 4 is an embodiment of the

inventive method shown. The method corresponds to a ramp-up of an operating voltage and the reaction of the affected circuit elements. In one First step 80, an operating voltage U _{G is} powered up from a power source. In a second step 81, it is determined whether the voltage is a threshold value

exceeds. If this is not the case, the first step 80 is continued. If this is the case, then a third step 82 is continued. In the third step 82, an auxiliary LED route is activated.

The process continues with a fourth step 83. In the fourth step 83, the operating voltage U _{G is} further increased. It is continued with a fifth step 84. It is now determined whether the voltage is a

Threshold voltage of an LED track exceeds. If this is not the case, the fourth step 83

continued. If this is the case, a sixth step 85 is continued. In the sixth step 85, the LED route is activated. The said steps are repeated each time the operating voltage U _{G is raised} .

When the operating voltage UG shuts down, the steps are carried out in the reverse order. That After an initial shutdown of the voltage, it is first checked whether the threshold voltage of the LED track has been undershot. If this is the case, then the LED route is deactivated. After further lowering of the voltage is checked whether the threshold was exceeded. As soon as the threshold value has been undershot, the auxiliary LED route is deactivated.

The invention is not limited to that shown

Embodiment limited. In particular, any number of different LEDs can be used. The only important thing is that the directly from the current source 21 LEDs differ in terms of their radiation characteristics of the operated by the power source 60 LEDs. All above

described features or shown in the figures

Features are in the context of the invention arbitrarily advantageous combined.

The use of a high-frequency clocked second power source also ensures a safe and constant operation of the auxiliary LED track, since the operation of this auxiliary LED track is done by an independent of the regulation of the LED route control. At the same time, the LED track is evenly loaded by the high frequency clocked second power source, as due to the

high-frequency clocking a uniform power consumption is ensured by the high-frequency clocked second power source.

Claims

claims

1. operating circuit for a LED track (30) with

at least one LED (31-39) of a first type (w) and an auxiliary LED path (70) with at least one LED (63) of a second type (a) whose spectrum differs from the first type (w),

wherein the operating circuit is designed to be supplied by a first current source (21) with an adjustable, preferably regulated total current (I _G ), wherein a main current (Ii) through the LED path (30) directly from the total current (IG ) is taken care of,

characterized,

in that the operating circuit has a second current source (60) which is supplied by the total current (IG) and supplies the auxiliary LED path (70) with an auxiliary current (I ₂ ), and

the operating circuit has a control circuit (40),

which controls the second current source (60) in response to a voltage (U _G ) on the LED path (30).

2. Operating circuit according to claim 1,

characterized,

in that the control circuit (40) is designed

to control the second current source (60) when a threshold voltage is exceeded by the voltage (U _G )

to supply the auxiliary LED path (70) with the auxiliary current (I ₂ ), and

in order to control the second current source (60) when the threshold value is undershot by the voltage (U _G )

To supply auxiliary LED track (70) not with the auxiliary power (I ₂ ), and a threshold voltage of the LED track (30) is greater than the threshold value.

3. Operating circuit according to claim 2,

characterized,

the second current source (60) is designed in such a way that, when the total current is amplitude-dimentional, the auxiliary current (I2) is constant through the auxiliary LED path (70) and the auxiliary LED path (70) emits constant light, as long as the LED track (30) receives a main current (Ii) and thus emits light, and

the auxiliary current (I ₂ ) is subject to amplitude dimming by the auxiliary LED path (70) and the auxiliary LED path (70) dimms light as long as the LED path {30) does not receive a main current (Ιχ) and so on no light

emitted.

4. Operating circuit according to claim 2 or 3,

characterized,

the second current source (60) is designed in such a way that, when dimming by means of pulse width modulation of the total current (IG), the auxiliary current (I ₂ ) through the auxiliary LED path (70) follows the course of the total current (I _G ) and the Auxiliary LED track (70) so dimmed emitted light.

5. Operating circuit according to claim 2 or 3,

characterized,

the second current source (60) is designed in such a way that, when dimming by means of pulse width modulation of the total current [IG], the auxiliary current (I2) has no pulse width modulation by the auxiliary LED segment (70) and the auxiliary LED segment (70 ) emits light that is constant and undimmed.

6. Operating circuit according to one of claims 2 to 5, characterized

in that the control circuit (40) has a comparator (54) which compares the voltage at least indirectly with the threshold value,

in that the control circuit (40) is designed to transmit a control signal to the second current source (60) as a function of the comparison,

in that the second current source (60) is designed to supply the auxiliary LED path (70) with the auxiliary current (± 2) as a function of the control signal, and

in that the control circuit (40) has a switch, preferably a transistor (48), which generates the control signal as a function of the comparison.

7. operating circuit according to claim 6,

characterized,

in that the comparator (54) has a voltage divider (51) and a voltage reference (52),

that the voltage divider (51) reduces the voltage by a factor,

the voltage reference (52) generates a reference voltage which is the factor reduced by the factor

Threshold equals, and

that the comparator (54) the degraded

Operating voltage with the constant voltage of

Voltage reference compares.

8. LED module with at least one operating circuit according to one of claims 1 to 7 and an LED track (30) with at least one LED {31 - 39) of a first type (w) and an auxiliary LED track (70) with at least one LED (63) of a second type (a), wherein LEDs (31-39) of the first type (w) and LEDs (63) of the second type (a) have different emission spectra.

9. LED light, prefers retrofit LED light with

at least one LED module (22) according to claim 8 and a first current source (21).

10. A method for operating an LED track (30) with at least one LED (31-39) of a first type (w) and an auxiliary LED track (70) with at least one LED (63) of a second type (a) whose spectrum differs from that of the first type,

wherein the LED path (30) and the auxiliary LED path (70) are supplied by an adjustable, preferably regulated total current (I _G ),

wherein a main current (Ι) is supplied by the LED path (30) directly from the total current (I _G ),

characterized,

the auxiliary LED path (70) is supplied with an auxiliary current (I ₂ ) which is supplied by the total current (I _G ),

the auxiliary current (I ₂ ) is controlled as a function of a voltage (U _G ) on the LED path (30).

11. The method according to claim 10,

characterized,

that when a threshold is exceeded by the

Voltage (U _G ), the auxiliary LED track (70) with the

Auxiliary current (I ₂ ) is supplied, and

that falls below the threshold by the

Voltage (U _G ), the auxiliary LED path (70) is not supplied with the auxiliary current (I ₂ ), and a threshold voltage of the LED track (30) is greater than the threshold value.

12. The method according to claim 11,

characterized,

that when the total current (I _G ) is amplitude-tuned, the auxiliary current (I ₂ ) is set constant by the auxiliary LED path (70) and light is constantly emitted by the auxiliary LED path (70) as long as the LED Line (30) receives a main current (Ii) and thus emits light, and

the auxiliary current (I ₂ ) is adjusted by the auxiliary LED path (70) so that it is subject to an amplitude dimming and thus dimmed by the auxiliary LED path (70) dimmed light, as long as the LED path (30 } does not pick up a main current (Ii) and so does not emit light.

13. The method according to claim 11 or 12,

characterized,

in the case of dimming by means of pulse width modulation of the total current (I _G ), the auxiliary current (I ₂ ) is set by the auxiliary LED path (70) so that it follows the course of the total current (I _G ) and the auxiliary LED Stretch (70) so dimmed emitted light.

14. The method according to claim 11 or 12,

characterized,

that when dimming by means of pulse width modulation of the total current (I _G ), the auxiliary current (I ₂ ) through the auxiliary LED path (70) is set so that it no

Pulse width modulation and the auxiliary LED path (70) emits light so constant and undimmed.