Circuit arrangement, lighting means and method

Abstract

A circuit arrangement comprises a set input (10) for supplying a set signal, a first current branch (2) having a first controllable path (20) and at least one optoelectronic component (21) arranged in series therewith, and a second current branch (3) having a second controllable path (30) and at least one optoelectronic component (31) arranged in series therewith. A controllable current-regulated converter (4) is connected to both current branches (2, 3) for supplying a total current. Furthermore, a control circuit (5) having a control input is provided, which control input is connected to the set input (10), wherein the control circuit (5) is coupled to the first controllable path (20) in order to adjust a current through the first current branch (2) on the basis of the set input (10). The second controllable path (3) is coupled to the first current branch (2) and to the set input (10) to form a control loop and is designed to control a current through the second current branch (3) depending on an operating state through the first current branch (2) and on the set signal.

Description

[0001] CIRCUIT ARRANGEMENT, LIGHTING METHOD AND METHODS

[0002] This application claims priority from German patent application DE 10 2024 105 650 . 9 of 28 February 2024, the disclosure of which is hereby incorporated in its entirety by reference.

[0003] The present invention relates to a circuit arrangement, in particular for supplying optoelectronic components.

[0004] BACKGROUND

[0005] In various automotive applications, replaceable bulbs are often used for headlights. The bulbs are provided with a closure and are inserted into the headlight when needed. In addition, the bulbs must also be suitable for various operating modes and, in addition to the actual - often optoelectronic - components, also feature converters and other control circuits. A typical application is replaceable bulbs for so-called low-beam and high-beam headlights, which provide different illumination of the road or different beam guidance depending on the operating state.

[0006] While the operating state is specified externally, the light source itself should determine the current, voltage, and other parameters. In particular, the light intensity should be variable in order to achieve the two operating states. For this purpose, several light sources are often installed in the headlight and these are controlled individually. In the past, it was common practice to control the individual light sources individually and independently of one another and to install them separately in the headlight. This means that, for example, a number of first light sources are used for low-beam operation, and then second light sources for high-beam operation.

[0007] In order to meet the different requirements, the prior art provides, for example, for assemblies with several optoelectronic components to be operated in parallel, which in turn are connected in series. This so-called parallel operation of so-called LED strings (i.e. several optoelectronic components in series) is difficult due to the different forward voltages of the LEDs. This problem can be avoided by appropriate binning, i.e. selecting the individual LEDs with a suitable forward voltage, but this is associated with increased costs due to the additional selection process. Alternatively, a separate current transformer and a separate control circuit can be provided for each branch, which likewise increases costs.With a single converter, either balancing resistors in the individual phases or the aforementioned tight forward voltage binning are necessary. Furthermore, depending on the operating condition, larger power losses may occur, which are determined by the specific design used.

[0008] The different requirements lead to increased costs. While these balancing resistors can reduce the deviation in the individual LED strings, this is associated with greater power losses and thus greater heat generation. Such a reduction, in turn, leads to increased switching complexity and thus to further costs for the existing state-of-the-art solutions.

[0009] This results in various requirements, including the elimination of binning when selecting LEDs with regard to forward voltage, while simultaneously reducing power loss in the individual power sources or driver circuits. Ideally, especially for automotive applications, different operating modes should be freely configurable in the respective LED strings, both in the selection of the individual strings and in terms of the current through the branches. To avoid possible damage due to excessive heat generation, a so-called derating behavior in the various current branches is also desired. This means that the individual current branches can be controlled differently with regard to their power consumption or current flow, thus controlling the current through the strings. SUMMARY OF THE INVENTION

[0010] These and other requirements are met by the subject matter of the independent patent claims. Refinements and developments of the invention are the subject matter of the dependent claims.

[0011] The inventor proposes a solution which requires only one converter and one power transistor as the controllable path or controllable current source for each current branch. This is achieved by a simple but inventive interconnection of the controllable paths. One controllable path of one current branch is used as a simple current regulator, while the other controllable path is interconnected in such a way that it is operated as an "inverse follower" depending on the current through the first current branch. This behavior corresponds to an inverse control loop. This means that the controllable path of the first current branch controls the current through the first current branch in such a way that the total current remains essentially constant, with the current in the first branch being regulated to a setpoint.

[0012] For example, the controllable path of the second current branch increases the current through the second current branch when the total current increases or the current through the first branch decreases. This results in the total current through the converter, which is then distributed among the respective current branches.

[0013] As a result, according to the inventive principle, the second controllable path follows the controllable path in the first current branch in an inverse manner. At the same time, a control system is provided that adjusts the first controllable path to the required target current value through the first branch. This regulates the forward voltage of the individual optoelectronic components in the respective branches so that an optimal operating point is achieved with very low losses in the controllable paths and the control circuit.

[0014] The inventor also proposes using the controllable paths to switch the respective branch on or off. This makes it easy to use in the automotive sector for low-beam or high-beam control. In particular, this eliminates the need to increase the number of components; instead, the circuits used to control the currents in the respective branches are also used to switch the respective branch on or off. The individual current branches can be supplied with power together by a controlled converter, with the controlled converter setting the total current. This reduces costs.

[0015] A circuit arrangement is therefore proposed which comprises a number of current branches, whereby on the one hand the controlled paths provided in the respective beam branches act as switches, but on the other hand also as controllers or followers for this controller. If only one branch is to be supplied with current, the controlled paths work as switches; however, if both branches are supplied with current ("high-beam" operation), one current branch is set to a target current value, and the second follows this in an inverse manner, so that a predetermined total current is set. This means that only one branch is used in low-beam operation, while in high-beam operation the optoelectronic components of both branches are used. This solution is significantly cheaper than conventional solutions in which the lights are designed for either low-beam operation or high-beam operation.

[0016] According to the proposed principle, in some embodiments, a circuit arrangement is proposed which has a set input for supplying a set signal . The circuit arrangement comprises a first current branch with a first controllable path and an optoelectronic component arranged in series therewith . Furthermore, a second current branch with a second controllable path is provided, which likewise comprises at least one optoelectronic component arranged in series therewith . According to the proposed principle, the first and second current branches are thus connected in parallel . Both branches are connected to a controllable current-regulated converter which serves to supply a total current to the two branches .

[0017] According to the invention, the circuit arrangement further comprises a control circuit with an input which is connected to the set input. The control circuit is coupled to the first controllable path for setting a current through the first current branch as a function of a signal at the set input. In other words, the control circuit serves to generate a target current value through the first current branch by means of the first controllable path. The second controllable path is then coupled to the first current branch and to the set input, in particular by forming an inverse control loop. The second controllable path is designed to control a current through the second current branch as a function of an operating state by the first current branch and the set signal.

[0018] As explained above, this dependence on the operating state occurs in such a way that the sum of the currents through the respective two current branches essentially results in the total current provided by the controllable converter.

[0019] In a further aspect, the first controllable path comprises a field-effect transistor with a node that is connected to the optoelectronic component arranged in series. The field-effect transistor is connected to a common potential node at another node. In this context, in some aspects, the first controllable path can also comprise a current mirror or a plurality of field-effect transistors. What is important here is that the first controllable path (and in some aspects also the second controllable path) regulate a current through the respective branch, for example by means of field-effect transistors. The use of field-effect transistors is expedient because they can be switched off when current is applied and have only a very low resistance, which reduces power loss. Bipolar transistors are also possible, however.

[0020] Correspondingly, in some aspects the second controllable path also comprises a field effect transistor which is connected at one node to the optoelectronic component of the second branch arranged in series and at the other node to the common potential node. The at least one optoelectronic component can comprise one or more components. For example, it is possible to connect several LEDs of the same type in series or in parallel. In general, the at least one arranged optoelectronic component can be described as a lighting device, wherein the implementation of such a lighting device can be designed in different ways.In this way, the circuit arrangement can also be used flexibly for different applications, in which different current branches with different consumers are provided, which are controlled depending on a set signal and, after activation, are regulated to a total current value by another branch.

[0021] In a further aspect, the second controllable path is designed to control the current through the second current branch as a function of the set signal, depending on a current through the first branch or a signal derived therefrom. In addition, the second controllable path is in some aspects also designed to interrupt a current through the second current input as a function of the set signal. This results in two possible operating states in the second current branch. On the one hand, a current through the second current branch can be completely interrupted, and on the other hand, the current through the second current branch is regulated to a total current value as a function of the current through the first branch.

[0022] In further aspects, it is provided that the second controllable path is designed such that a current through the second current branch is set or regulated as a function of a voltage drop across at least part of the first current path, in particular comprising the at least one optoelectronic component. The setting is carried out such that the total current in the first and second branches results from the sum of the individual currents. If the current in the first branch thus increases, the regulation is carried out such that the current in the second branch is reduced and vice versa.

[0023] In an alternative embodiment, the second controllable path is designed to adjust a current through the second current branch as a function of a voltage drop across the first controllable path in the first current branch. In a further embodiment, the second controllable path is designed to adjust a current through the second current branch as a function of a current flow through the first controllable path in the first current branch.

[0024] A further aspect relates to the selective switching on and off of the second current branch. For this purpose, a switching element can be provided in the current branch itself, the switching input of which is connected to the set input. Depending on the control, the second current branch is thus interrupted. In a second aspect, the second controllable path has a switching element whose switching input is connected to the set input. This switching element is designed, depending on the signal at the switching input and thus the signal at the set input, either to activate the current control of the second controllable path or to bring about an interruption of current through the second current branch by means of the second controllable path. This can be achieved by the switching element, for example, in that it completely switches off the second controllable path or connects it to the first current branch for setting in an inverse control as explained above.

[0025] Another aspect relates to the control circuit for setting a current through the first current branch by controlling the first controllable path. For this purpose, in some aspects the control circuit comprises a path consisting of a resistor and a current-controlled path with a tap arranged therebetween. The tap is connected to a control input of the first controllable path. The current-controlled path is in turn fed back to the first current branch for setting an operating point. This makes it possible to control the first controllable path to a fixed value. The current through the first or second current branch is then controlled by setting a total current by means of the current-controlled converter. In an alternative embodiment, a signal for setting the operating point can also be supplied to the current-controlled path so that the current in the first branch can be controlled to any value.Another aspect is that in some applications, the current through the optoelectronic components must be reduced to protect them from damage due to excessive heat generation. Therefore, in some aspects, the circuit arrangement includes a temperature sensor. The temperature sensor is coupled to a control input of the current-controlled converter. The converter is designed to regulate the total current as a function of a signal at its control input and thus to reduce the total current, particularly when the temperature rises.

[0026] According to the proposed principle, the circuit arrangement is thus designed such that when the total current is reduced through the current-controlled converter, the current in the second current path is first reduced and only then the current in the first current path is also reduced. This has the effect that when the total current is reduced, the second current path is first regulated down and then switched off before regulation takes place in the first current path. In an application with low-beam operation and high-beam operation, this ensures that the branch for the low-beam light component always continues to operate, while the branch for the high-beam is only activated after appropriate control and activation in this operating mode. Likewise, when the total current is reduced, the current through the branch for high-beam operation is first reduced.Especially in the automotive sector, this means that low-beam operation is maintained as far as possible even in the event of greater heat development or other conditions that lead to a reduction in the overall current.

[0027] A further aspect relates to a lighting means with a circuit arrangement according to the proposed principle. The lighting means has a housing in which the circuit arrangement is arranged, and a socket which is configured to insert the lighting means into a headlight. According to the invention, the at least one optoelectronic component of the second current branch is arranged such that, during operation, a light cone generated by this component only insignificantly overlaps with a light cone which is formed by the at least one optoelectronic component of the first current branch. As a result, the low beam and the high beam can be provided with one lighting means.

[0028] Another aspect relates to a method for operating an arrangement comprising a converter and two current branches arranged in parallel thereto, each current branch comprising at least one optoelectronic component and a controllable path connected in series thereto. In the method, among other things, a total current is provided through the converter and at least one of a first and a second operating mode is selected by means of a selection signal. The different operating modes are characterized by different types of control of the controllable paths in the first and second branches. In the first operating mode, the controllable path in the second current branch is deactivated so that no current flows through the second current branch. Likewise, the controllable path in the first current branch is activated, the current through the first circuit substantially corresponding to the total current provided.The controllable section of the first circuit is thus operated in a switching mode.

[0029] In the second operating mode, however, the controllable paths in both current branches are activated. The controllable path in the first current branch is also controlled so that a defined setpoint is reached. The controllable path in the second current branch is controlled by a signal derived from a current through the first current branch. This means that the total current, as the sum of the two individual currents, remains constant in each of the two operating modes, with the controllable path in the second circuit representing an inverse follower of the path in the first current branch.

[0030] A further aspect relates to de-rating, i.e. a change, often a reduction, in the current due to an external effect. In this case, for example, a temperature or another parameter is detected and, based on this, a total current is set as a function of the temperature. In the second operating mode, the controllable path in the first current branch is then set to the defined setpoint. The controllable path in the second current branch is controlled based on a current in the first current branch or a signal derived therefrom.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further aspects and embodiments according to the proposed principle will become apparent with reference to the various embodiments and examples which will be described in detail in conjunction with the accompanying drawings.

[0033] Figure 1 shows a first embodiment of a circuit arrangement according to some aspects of the proposed principle;

[0034] Figure 2 shows a second embodiment of a circuit arrangement according to some aspects of the proposed principle;

[0035] Figure 3 shows a third embodiment of a circuit arrangement according to some aspects of the proposed principle;

[0036] Figure 4 is a diagram illustrating the respective branch current as a function of a total current set by the converter, which is set in a circuit arrangement according to some aspects of the proposed principle;

[0037] Figure 5 is a schematic diagram of a headlight assembly with a light source according to some aspects of the proposed principle.

[0038] DETAILED DESCRIPTION

[0039] The following embodiments and examples show various aspects and their combinations according to the proposed principle. The embodiments and examples are not always true to scale. Likewise, various elements can be shown enlarged or reduced in size to emphasize individual aspects. It goes without saying that the individual aspects and features of the embodiments and examples shown in the figures can be combined with one another without thereby impairing the inventive principle. Some aspects have a regular structure or shape. It should be noted that in practice slight deviations from the ideal shape can occur without, however, contradicting the inventive idea.

[0040] Furthermore, the individual figures, features, and aspects are not necessarily shown in the correct size, and the proportions between the individual elements may not always be correct. Some aspects and features are emphasized by being shown enlarged. However, terms such as "top", "above", "below", "below", "larger", "smaller", and the like are correctly represented with reference to the elements in the figures. This makes it possible to infer such relationships between the elements from the illustrations.

[0041] Figure 1 shows an embodiment of a circuit arrangement according to the proposed principle.

[0042] The circuit arrangement 1 comprises a first current branch 2 and a second current branch 3, which are connected in parallel to a current-controlled converter 4. The current-controlled converter 4 supplies the two current branches with a corresponding current. Each current branch comprises, on the one hand, at least one optoelectronic component 21 or 31, which are each connected in series with a controllable path 20 and 30. By means of the controllable paths 20 and 30, a current through the respective current branch can be adjusted. Accordingly, the current in the two branches is divided between the respective parallel strands by adjusting the two controllable paths.

[0043] The total current is provided by the controller 4 and corresponds to the sum of the two individual currents in the current branches 2 and 3. According to the proposed principle, the first controllable path 20 comprises a control input 201 which is connected to a control circuit 5. The control circuit 5 detects a signal in the first current branch which corresponds to a current through this current branch. This can be, for example, a voltage drop across the optoelectronic component 21, a voltage drop across the controllable path 20, a voltage drop across a current shunt or even the current itself through the respective current branch.

[0044] Depending on this, the control circuit 5 controls the controllable path such that a desired and predefined target current value is established. The second controllable path 30 comprises a set input 301 and a control or regulating input 302. In the present case, the set input 301 completely switches off the second controllable path 30 and thus separates the second current branch 3 from the converter 4 and thereby prevents current flow. The control or regulating input 302 is, on the other hand, connected to the first controllable path 20. A signal is detected here by the second controllable path 30 which regulates the current through the second current branch of the second controllable path depending on a current flow or an operating state of the first controllable path.

[0045] It should be noted that the second current branch 3 is not a control with an independent setpoint. Rather, the setpoint is derived from the current setpoint of the converter 4 and the setpoint of the first current branch 2. This current, corresponding to the difference between the setpoints of 4 and 2, is then kept constant - even in the event of a possible voltage change of the optoelectronic component 31. By means of a set signal at the set input 10, to which the control circuit 5 is connected, the second current branch 3 can be switched into two different operating states. On the one hand, this is a separation of the second current branch 3 from the converter 4 by a corresponding signal at the set input 301 and, on the other hand, an activation of the second current branch with simultaneous current control as explained above. At the same time, when the second current branch 3 is separated from the converter 4, the set input deactivates the controller 5.This results in two possible states as follows. In what is known as LB operation, for example low-beam operation in the automotive sector for illuminating an apron, the first current branch 2 is activated and the current is regulated by the converter 4. The current is therefore specified by the converter 4 and the second current branch 2 is switched off. In this state, the current follows through the first current branch 2 without any further control operation, i.e. the current through the first circuit is specified by the total current of the converter 4. The first circuit 2 operates in switching mode.

[0046] In a second operating state, the second current branch 3 is activated, while at the same time the first current branch 1 is controlled to a setpoint current value. This is achieved by analog control via the control loop 5 and by detecting a voltage drop or current flow and simultaneous control in the second current branch through the controllable path. Accordingly, the current through the second current branch 3 results from the specified total converter 4 and the current controlled by the first current branch 2.

[0047] Figure 2 shows a further embodiment of the invention. Components bear the same reference numerals.

[0048] In this exemplary embodiment, in contrast to the previous exemplary embodiment, two additional switching elements 22 and 32 are connected in the respective current branches 2 and 3. The control loop also comprises a set input 10, with which each of the two current branches 2 or 3 can be selectively activated or deactivated by the switch 22 or 33. On the one hand, this arrangement allows the two current branches to be operated independently and separately from one another. On the other hand, the existing control of the second controllable path remains in place as an inverse follower of the first controllable path. When the two current branches are activated, the current through the first current branch is controlled by setting a fixed operating point or a set point predetermined by the control loop 5.In this operating mode, the current through the second current branch is controlled by detecting a signal derived from the first current branch, taking the total current into account. If the total current or the current through the first current branch changes, the second circuit follows in such a way that the total current is restored. Accordingly, the current through the second current branch is the difference between the total current and the current through the first current branch 2. Figure 3 shows an embodiment of a circuit arrangement according to the proposed principle.

[0049] The circuit arrangement comprises a converter 4, which is connected here as a regulated current source. The controllable paths 2 and 3 are arranged in parallel to the converter 4. The controllable path 2 comprises three optoelectronic components D1, D2 and D3 connected in series, which are combined as an optoelectronic component 21. The controllable path is implemented by means of a field-effect transistor 200, the source and drain connections of which are connected in series to the component 21. Furthermore, a resistor RI is provided between the field-effect transistor 200 and the ground potential connection GND, which resistor is used to set an operating point and thus forms part of a control circuit 5 which will be explained in more detail below.

[0050] The second controllable path 3 also comprises three series-connected diodes D4, D5, and D6, which form the optoelectronic component 31. Here, too, a field-effect transistor 300 is provided as part of the controllable path and is connected in series with the three LEDs D4, D5, and D6 in the current branch.

[0051] A series of a resistor R4 and a bipolar transistor Q3 is arranged in parallel with the second current branch 3. The bipolar transistor Q3 simultaneously forms a switching element 32', which is connected to the set input 10 at its base terminal. The gate terminal of the field-effect transistor 300 forms the control terminal 301 and is connected between the bipolar transistor Q3 and the resistor R4. A second control tap 302 is connected via a further resistor R3 to a break between the field-effect transistor 200 and the optoelectronic component 21 of the first current branch 2.

[0052] The control loop 5 further comprises a second bipolar transistor Q2, whose control terminal 320 is also connected to the set input 10. The emitter of the bipolar transistor Q2 leads to the base of a bipolar transistor Q1, which, together with a resistor R2, forms a controlled path 50. At a further tap between the bipolar transistor Q1 and the resistor R2, a connection leads to the control input 201 as the gate terminal of the field-effect transistor 200.

[0053] Operation at a predetermined total current through the converter 4 is now achieved via a corresponding set signal at input 10. If this set signal is at a logic high level H, the two bipolar transistors Q3 and Q2 become low-impedance because the respective base-emitter path is switched on. Accordingly, the collector of the two transistors is pulled to a low potential, taking into account a voltage drop across the two transistors Q2 and Q3. This results in the set input 302 of the second field-effect transistor 300 being at a low potential and thus this branch is completely switched off. In this context, the field-effect transistor 300 therefore works as a switch, blocks and switches off the second current branch 2.

[0054] At the same time, the base of transistor Q1 in controlled path 50 is pulled to a low potential, so that the base-emitter path of transistor Q1 becomes highly resistive. This results in a signal at the control input 201 of field-effect transistor 200 with a high logic level, causing it to turn on completely. Accordingly, transistor 200 also operates in a switching mode, and a current flows through the first current branch without any major regulation. The total current through the first current branch 2 is determined solely by converter 4.

[0055] A logic low potential is now applied to the set input 10. This causes the two transistors Q3 and Q2 to become correspondingly high-impedance. In the controlled path 50, a voltage is thus applied to the base of the transistor Q1, which results from the voltage across the resistor RI.

[0056] The operating point setting of the base of transistor Q1 leads to a controlled potential at tap 201 and the gate terminal of field effect transistor 200 and thus to a regulated current through the first current branch. In particular, the channel of field effect transistor 200 is opened or closed by the potential at tap 201. If the base of transistor Q1 becomes correspondingly lower, i.e. less current flows through the base of transistor Q3, the latter becomes more high-impedance. The potential at tap 201 therefore increases and as a result the field effect transistor 200 reduces its channel resistance, whereby the current through the first current branch increases. If, on the other hand, the voltage at the base of bipolar transistor Q1 increases, the voltage at the gate terminal of transistor 200 decreases and the current flow through current branch 2 is reduced.

[0057] In this consideration, without taking the resistor R3 into account, a high potential is applied to this gate terminal in current branch 2, as a result of which the field-effect transistor 300 becomes conductive and leads to a current flow through the second current branch. The resistor R3, which is arranged between the tap 302 and a node between the optoelectronic component 21 and the field-effect transistor 200 of the first current branch, serves to inversely regulate the current through the second current branch. In particular, a voltage division takes place here by the resistors R3 and R4. An increased current flow through the field-effect transistor 200 leads to a reduction in the potential at the tap 302. This increases the channel resistance in the transistor 300, as a result of which the current flow in the second current branch 3 is reduced.If, on the other hand, the current through the first field-effect transistor 200 decreases, the potential attack 302 increases and the second field-effect transistor 300 becomes somewhat lower-resistance (channel opens), so that the current flow increases. The field-effect transistor 300 therefore works as an inverse follower with feedback to the first current branch. The required resistance values ​​of the drain-source paths in the two field-effect transistors 200 and 300 are automatically set by the feedback. The resistors R3, R4 and R5 determine the operating point and thus also the essential power loss in the circuit arrangement. At the same time, the bipolar transistors Q2 and Q3 form switching elements for controlling the two strands for low-beam and high-beam operation, for example in an automotive application. In some aspects it is necessary to carry out what is known as derating, i.e. a desired reduction in the overall current.The total current is deliberately reduced, for example, to prevent further heating of the optoelectronic components. For this purpose, the circuit according to the proposed principle allows the current in the second current branch 3 to be regulated downwards if the total current—specified by the converter 4—should change, and in particular, decrease.

[0058] As already explained, the total current is the sum of the two individual currents in current branches 2 and 3, whereby the total current can be adjusted by the converter 4. If the total current is now changed, for example reduced, and the two current branches are operated simultaneously, the current through the second current branch should be reduced first, so that the sum of the two currents follows the total current. At the same time, the current in the first current branch should be kept essentially constant. Only when a minimum is reached is the second current branch switched off and the first current branch goes into the switching operation described above.

[0059] A change in the current in the second current branch in response to a change in the total current is achieved by the circuit arrangement according to the invention by means of the inverse feedback of the second controllable path 30 and the field-effect transistor 300 to the first controllable path 20 and the first field-effect transistor 200. With a reducing total current, the control circuit 50 and the operating point setting ensure that the behavior of the field-effect transistor 200 in the first current branch remains essentially constant. In other words, the current in the first current branch remains essentially constant because the channel of the field-effect transistor 200 is increasingly driven. Accordingly, the potential at the node between the optoelectronic component 21 and the field-effect transistor 200 continues to decrease, so that the potential at the tap 302 also decreases.The channel resistance in the field effect transistor 300 increases accordingly, as a result of which the current in the current branch 3 decreases. This effect can be illustrated in Figure 4, which shows the path current through the two current branches 2 and 3 as a function of the total current. The total current is indicated on the x-axis and lies between 1 A and 2 A. It results from the sum of the two individual currents in branches 2 and 3. It can be seen that when the total current on the x-axis changes, for example from 1.4 A to 1.8 A, the current in the first current branch 2 remains essentially constant. In contrast, the current in the second current branch increases from approximately 0.55 A to approximately 0.9 A during high-beam operation. This means that in this range of the total current, when the first and second current branches are activated, de-rating occurs solely via the current flow through the second current branch. Only when the current falls below a minimum value of approx.1 A, the second current branch is completely switched off and the current is reduced solely via the first current branch.

[0060] Figure 5 shows a typical application in the automotive sector. It involves a lamp that contains the optoelectronic components, the two current branches, the converter arrangement, and all other switching elements. This lamp is mountable, i.e., it can be used in a headlight or a lamp. Such an application thus allows the lamp to be easily replaced in the event of damage or destruction, thus ensuring continuous operation.

[0061] The headlight comprises one or two mechanical deflection elements 99, which are illuminated differently by the light source depending on the respective operating state. The optoelectronic components in the two current branches are arranged in such a way that they allow illumination in different operating modes. So-called low-beam operation, when only the first current branch 2 is controlled, produces a dependent desired light cone. In high-beam operation, the second current branch is also switched on, increasing the total current and thus the total amount of light. In contrast to conventional solutions, the components, in particular the optoelectronic components of the first current branch, are used for both low-beam and high-beam operation. This increases the luminous efficacy, especially in the high-beam range, without the need for additional optoelectronic components.

[0062] LIST OF REFERENCE SYMBOLS

[0063] Circuit arrangement, 3 current branches

[0064] converter

[0065] Control circuit 0 Set input 0 Controllable path 1 Optoelectronic component 2 Switch 0 Controllable path 1 Optoelectronic component 2 , 32 ' Switch 1 Temperature sensor 0 Path 00 Field effect transistor 00 Field effect transistor

Claims

PATENT CLAIMS 1. A circuit arrangement comprising: a set input (10) for supplying a set signal; a first current branch (2) with a first controllable path (20) and at least one optoelectronic component (21) arranged in series therewith; a second current branch (3) with a second controllable path (30) and at least one optoelectronic component (31) arranged in series therewith; a controllable, current-controlled converter (4) connected to the first and second current branches (2, 3) for supplying a total current; a control circuit (5) with a setting input connected to the set input (10), the control circuit (5) being coupled to the first controllable path (20) for setting a current through the first current branch (2) as a function of the set input (10);wherein the second controllable path (3) is coupled to the first current branch (2) and to the setting input (10), in particular to form a control loop, and is designed to control a current through the second current branch (3) as a function of an operating state through the first current branch (2) and the setting signal; 2. Circuit arrangement according to claim 1, wherein the first and / or second controllable path each comprises a field effect transistor which is connected at one node to the at least one optoelectronic component arranged in series and is connected at the other node to a common potential node.

3. Circuit arrangement according to claim 1 or 2, wherein the second controllable path is arranged with its control connection to a node in the first circuit, in particular between the at least one optoelectronic component and the first controllable path.

4. Circuit arrangement according to one of the preceding claims, in which the second controllable path is designed, depending on the set signal, to control the current through the second current branch in dependence on a current through the first branch or a signal derived therefrom, or to interrupt a current through the second current branch.

5. Circuit arrangement according to one of the preceding claims, in which the second controllable path is designed to control a current through the second current branch in dependence on a Voltage drop across at least part of the first current path, in particular comprising the at least one optoelectronic component; Voltage drop across the first controllable path in the first current branch; and Current flow through the first controllable path in the first current branch; to be set.

6. Circuit arrangement according to one of the preceding claims, in which the second controllable path has a switching element (32, 32 ') whose switching input is connected to the setting input for setting a current control or a current interruption through the second current branch.

7. Circuit arrangement according to one of the preceding claims, in which the control circuit (5) comprises a path (50) consisting of a resistor and a current-controlled path with a tap arranged therebetween, which is connected to a control input of the first controllable path.

8. Circuit arrangement according to one of the preceding claims, further comprising a temperature sensor (41) coupled to a control input of the current-controlled converter (4). 9 . Circuit arrangement according to one of the preceding claims, designed to reduce a current in the second current path when the total current through the current-controlled converter ( 4 ) is reduced.

10. Lighting device comprising: A circuit arrangement according to one of the preceding claims, A housing in which the circuit arrangement is arranged, A socket for inserting the illuminant into a headlight, wherein the at least one optoelectronic component of the second current branch is arranged such that, during operation, a light cone generated by this component only insignificantly overlaps with a light cone formed by the at least one optoelectronic component of the first current branch.

11. Method for operating an arrangement comprising a converter and two current branches arranged in parallel thereto, each current branch comprising at least one optoelectronic component and a controllable path connected in series thereto, the method comprising the following steps: Providing a total current through the converter; Selecting at least one of a first and a second operating mode by means of a selection signal; wherein in the first operating mode, o the controllable path in the second current branch is deactivated; o the controllable path in the first current branch is activated, wherein the current through the first circuit substantially corresponds to the total current provided. In the second operating mode, o the controllable path in the second current branch is activated; o the controllable path in the first current branch is activated; o the controllable path in the first current branch is controlled such that a defined setpoint is established. o The controllable path in the second current branch is controlled by a signal derived from a current through the first current branch.

12. Method according to claim 11, wherein the total current provided in each of the two operating modes results from the sum of the two currents in the respective current branches.

13. Method according to claim 11 or 12, further comprising: Recording a temperature or other parameter; Setting a total current depending on the detected temperature or other parameter; In the second operating mode: o Controlling the controllable path in the first current branch to the defined setpoint o Controlling the controllable path in the second current branch based on a current in the first current branch or a signal derived therefrom and the total current of a controllable current-controlled converter (4).

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