DE102023105074A1 - Control device and method for setting several different operating voltages - Google Patents

Abstract

The invention relates to a control device (100) for controlling at least one LED group (200) comprising at least one LED (201, 202, 203). The control device (100) comprises a switching regulator (102). The control device (100) is designed to provide a plurality of operating voltages (V1, V2, V3). In particular, the control device (100) comprises a plurality of linear regulators (101), wherein each of the linear regulators (101a, 101b, 101c) is designed to individually set an operating voltage (V1, V2, V3) of the plurality of operating voltages (V1, V2, V3).The invention further relates to a method for setting a plurality of at least partially different operating voltages (V1, V2, V3) by means of the control device (100). A first control circuit (R1) of the control device (100) sets a plurality of operating voltages (V1, V2, V3) by means of a plurality of linear regulators (101a, 101b, 101c). At the same time, a second control circuit (R2) sets an input voltage (ES) for the linear regulators (101a, 101b, 101c).

Description

The invention relates to a control device for controlling at least one LED group comprising at least one LED.

The invention further relates to methods for setting a plurality of operating voltages which at least partially differ from one another.

Light emitting diodes are operated with a constant current. Linear current sources are usually used for this purpose. Linear current sources can be switched on and off quickly, which is advantageous for dimming pulse width modulation (PWM) and amplitude modulation (AM) of current pulses.

However, linear power sources used to drive LED strings have limited power efficiency, which is mainly due to voltage fluctuations of the LEDs. These voltage fluctuations are due to temperature dependence, scattering and aging.

If the LEDs in a string are supplied with a fixed voltage, the power sources connected in series with the LED strings can have a high voltage. The high voltage leads to high power dissipation, which in turn requires that the power sources must be suitable for high temperatures.

It is therefore desirable to reduce the power consumption due to voltage fluctuations of the semiconductor light-emitting device.

The US 8,319,449 B2 discloses a control device for controlling a light emitting diode (LED). The control device comprises a switching regulator which reduces or increases a supply voltage of the LED such that the voltage at the power source that supplies the LED remains at a minimum voltage that is necessary to ensure proper operation of the LED without generating an overvoltage at the power source that would be converted into heat. The supply voltage is regulated in relation to a measured value, the measured value being indicative of a voltage drop at the power source for determining a current through the light emitting diode.

The US 8,319,449 B2 discloses an application of several LED strings, each of the LED strings having LEDs of a specific color. A first LED string comprises only red LEDs, a second LED string comprises only green LEDs and a third LED string comprises only blue LEDs. Each LED string is assigned a power source. The power source of each LED string is switched by means of a PWM unit assigned to the respective LED string.

Each of the LED strings of a respective color is supplied with a respective supply voltage (Vr, Vb, Vg), whereby the respective supply voltages Vr, Vg and Vb are controlled in such a way that the voltage at the respective power sources of the LED strings is as low as possible, whereby the minimum voltage required to supply the LEDs is not undercut.

The US 8,319,449 B2 The disclosed circuit for controlling the differently colored LED strings has a separate switching regulator for regulating the respective supply voltage Vr, Vg, Vb for each corresponding LED string.

A separate switching regulator is therefore required for each individual LED string. The more LED strings that are to be controlled, the more switching regulators are required. This means that a large number of components are required. This leads to high costs. In addition, due to the large number of switching regulators required, the control circuit becomes larger the more LED strings are controlled.

The object of the present invention is therefore to provide a solution for an improved control device which prevents an overvoltage at a power source, wherein the solution should be cost-effective and have a compact design.

To solve the problem, a device and a method according to the independent claim are proposed.

Further advantageous embodiments of the invention can be taken from the dependent claims, the description and the figures.

The proposed solution provides a control device. In particular, the control device comprises a switching regulator. In particular, the control device is designed to provide a plurality of operating voltages.

In particular, the control device comprises a plurality of linear regulators. In particular, each of the linear regulators is designed to individually adjust an operating voltage of the plurality of operating voltages.

In particular, the control device is suitable for controlling at least one LED group. In particular, the at least one LED group comprises at least one LED.

In particular, the at least one LED group comprises a plurality of LEDs.

In particular, all LEDs of a plurality of LEDs of the at least one LED group are of the same color.

In particular, the at least one LED group comprises LEDs of at least two different colors.

However, the control device can also be used for other consumers apart from LEDs, which are operated with at least partially different operating voltages.

In one embodiment, the control device comprises a first control loop and a second control loop.

In particular, the first control circuit regulates the respective operating voltages.

In particular, the second control loop regulates an input voltage for the linear regulators.

In one embodiment, the first control loop comprises the linear regulators. In particular, the first control loop is designed to use the linear regulators to set the plurality of operating voltages in such a way that the operating voltages are at least partially different from one another. In particular, the first control loop regulates the setting of the at least partially different operating voltages using the linear regulators.

In particular, the first control circuit is configured to set a first operating voltage by means of a first linear regulator.

In particular, the first control circuit is designed to set a second operating voltage by means of a second linear regulator,

In particular, the first control circuit is designed to set a third operating voltage by means of a third linear regulator,

In particular, the first control loop is designed to set a fourth operating voltage by means of a fourth linear regulator.

In one embodiment, the second control loop comprises the switching regulator. In particular, the second control loop is designed to set the input voltage for the linear regulators by means of the switching regulator.

In particular, the second control loop regulates the setting of the input voltage for the at least one linear regulator by means of the switching regulator.

In one embodiment, the control device is designed to supply LEDs of different colors with different operating voltages.

In particular, a first linear regulator is configured to set a first operating voltage. In particular, a second linear regulator is configured to set a second operating voltage that is different from the first operating voltage.

In particular, a first linear regulator sets a first operating voltage for all LEDs of a first color for all LED groups.

In particular, a second linear regulator sets a second operating voltage for all LEDs of a second color for all LED groups.

In particular, a third linear regulator sets a third operating voltage for all LEDs of a third color for all LED groups.

In particular, a fourth linear regulator sets a fourth operating voltage for all LEDs of a fourth color for all LED groups.

In one embodiment, the control device comprises at least one power source. In particular, the at least one power source is designed to supply the at least one LED group with power.

In particular, each power source supplies power to one group of LEDs.

In one embodiment, the control device comprises at least one pulse width modulation unit.

In particular, the at least one pulse width modulation unit is configured to switch the at least one current source.

In particular, each pulse width modulation unit switches one current source.

In one embodiment, the linear regulators are designed as multiplexers.

In one embodiment, the at least one pulse width modulation unit is configured to assign a PWM duty cycle to the linear regulators individually and separately from one another. In particular, each of the linear regulators is assigned a PWM duty cycle.

In particular, the linear regulators are controlled by means of the switching regulator according to the corresponding operating voltage to be achieved and are additionally assigned a respective PWM duty cycle.

In particular, as a result of the PWM duty cycle, only the at least one LED of the at least one LED group is supplied with voltage, which at least one LED has a first color, and/or a second color, and/or a third color, and/or a fourth color.

In particular, as a result of the PWM duty cycle, the at least one LED of a plurality of LED groups is supplied with voltage, which at least one LED has the first color, and/or the second color, and/or the third color, and/or the fourth color.

In particular, a respective pulse width modulation unit assigns the PWM duty cycle to the linear regulators, which respective pulse width modulation unit controls a respective current source of a respective LED group.

In this way, the LEDs of a particular color can be dimmed individually for each LED group depending on a PWM duty cycle.

The proposed solution further provides a method for setting a plurality of operating voltages that differ at least in part from one another by means of the control device. In particular, the first control circuit of the control device sets the plurality of operating voltages by means of the plurality of linear regulators.

In particular, the second control loop sets the input voltage for the linear regulators.

1. a. Erfassen eines ersten Messwerts für einen Spannungsabfall über zumindest eine Stromquelle;
2. b. Vergleichen des ersten Messwerts mit einem vorgegebenen Maximalwert für den Spannungsabfall über die zumindest eine Stromquelle;
3. c. Senden eines ersten ersten Komparator-Signals;
4. d. Einstellen einer jeweiligen Betriebsspannung für jede der Mehrzahl von Betriebsspannungen entsprechend des ersten ersten Komparator-Signals;
5. e. Vergleichen der jeweiligen Betriebsspannung mit einem jeweiligen vorgegebenen Mindestwert für die jeweiligen Betriebsspannungen;
6. f. Vergleichen der jeweiligen Betriebsspannung mit einem jeweiligen vorgegebenen Maximalwert für die jeweiligen Betriebsspannungen;
7. g. Senden eines zweiten ersten Komparator-Signals; und
8. h. Einstellen einer jeweiligen Betriebsspannung für jede der Mehrzahl von Betriebsspannungen entsprechend des zweiten ersten Komparator-Signals,

wobei das Verfahren iterativ durchgeführt wird.In one embodiment, the first control loop comprises the following process steps:

1. a. detecting a first measured value for a voltage drop across at least one current source;
2. b. comparing the first measured value with a predetermined maximum value for the voltage drop across the at least one current source;
3. c. sending a first comparator signal;
4. d. setting a respective operating voltage for each of the plurality of operating voltages according to the first comparator signal;
5. e. comparing the respective operating voltage with a respective specified minimum value for the respective operating voltages;
6. f. Comparing the respective operating voltage with a respective specified maximum value for the respective operating voltages;
7. g. Sending a second first comparator signal; and
8. h. Setting a respective operating voltage for each of the plurality of operating voltages according to the second first comparator signal,

where the procedure is carried out iteratively.

In particular, the control device comprises a first detector. In particular, the first detector detects the first measured value for the voltage drop across the at least one current source. In particular, the control device comprises a first comparator. In particular, the first comparator compares the first measured value with the predetermined maximum value for the voltage drop across the at least one current source.

In particular, the first comparator sends the first first comparator signal. In particular, the first comparator sends the first first comparator signal to the linear regulators. In particular, the first comparator sends the first first comparator signal when the first measured value is greater than the predetermined maximum value for the voltage drop across the at least one current source. In particular, the linear regulators of the control device set a respective operating voltage for each of the plurality of operating voltages in accordance with the first first comparator signal. In particular, the first linear regulator sets the first operating voltage in accordance with the first first comparator signal. In particular, the second linear regulator sets the second operating voltage in accordance with the first first comparator signal. In particular, the third linear regulator sets the third operating voltage in accordance with the first first comparator signal. In particular, the fourth linear regulator sets the fourth operating voltage in accordance with the first first comparator signal.

In particular, the respective linear regulator reduces the respective operating voltage if the first measured value is greater than the specified maximum times the voltage drop across at least one current source.

In particular, the first comparator compares the respective operating voltages with a respective predetermined minimum value for the respective operating voltages.

In particular, the first comparator compares the respective operating voltages with a respective predetermined maximum value for the respective operating voltages.

In particular, the first comparator sends the second first comparator signal. In particular, the first comparator sends the second first comparator signal to the linear regulators. In particular, the first comparator sends the second first comparator signal when a respective operating voltage is less than or equal to the respective predetermined minimum value. In particular, the first comparator sends the second first comparator signal when a respective operating voltage is greater than or equal to the respective predetermined maximum value.

In particular, the respective linear regulators adjust the respective operating voltages according to the second first comparator signal. In particular, the first linear regulator adjusts the first operating voltage according to the second first comparator signal. In particular, the second linear regulator adjusts the second operating voltage according to the second first comparator signal. In particular, the third linear regulator adjusts the third operating voltage according to the second first comparator signal. In particular, the fourth linear regulator adjusts the fourth operating voltage according to the second first comparator signal.

In particular, the respective linear regulators increase the respective operating voltages when the respective operating voltage is less than or equal to the respective predetermined minimum value. In particular, the first linear regulator increases the first operating voltage when the first operating voltage is less than or equal to the predetermined minimum value of the first operating voltage. In particular, the second linear regulator increases the second operating voltage when the second operating voltage is less than or equal to the predetermined minimum value of the second operating voltage. In particular, the third linear regulator increases the third operating voltage when the third operating voltage is less than or equal to the predetermined minimum value of the third operating voltage. In particular, the fourth linear regulator increases the fourth operating voltage when the fourth operating voltage is less than or equal to the predetermined minimum value of the fourth operating voltage.

In particular, the respective linear regulators reduce the respective operating voltages when the respective operating voltage is greater than or equal to the respective predetermined maximum value. In particular, the first linear regulator reduces the first operating voltage when the first operating voltage is greater than or equal to the predetermined maximum value of the first operating voltage. In particular, the second linear regulator reduces the second operating voltage when the second operating voltage is greater than or equal to the predetermined maximum value of the second operating voltage. In particular, the third linear regulator reduces the third operating voltage when the third operating voltage is greater than or equal to the predetermined maximum value of the third operating voltage. In particular, the fourth linear regulator reduces the fourth operating voltage when the fourth operating voltage is greater than or equal to the predetermined maximum value of the fourth operating voltage.

1. a. Erfassen eines Temperaturwerts der zumindest einen Stromquelle;
2. b. Vergleichen des Temperaturwerts mit einem vorgegebenen Temperaturmaximalwert;
3. c. Senden eines zweiten Komparator-Signals, und
4. d. Einstellen der der jeweiligen Betriebsspannungen entsprechend des zweiten Komparator-Signals,

wobei das Verfahren iterativ durchgeführt wird.In one embodiment, the first control loop additionally or alternatively comprises the following process steps:

1. a. detecting a temperature value of the at least one power source;
2. b. comparing the temperature value with a predetermined maximum temperature value;
3. c. Sending a second comparator signal, and
4. d. Setting the respective operating voltages according to the second comparator signal,

where the procedure is carried out iteratively.

In particular, a temperature sensor detects the temperature value. In particular, the control device comprises the temperature sensor. In particular, the temperature sensor is arranged separately.

In particular, a second comparator compares the temperature value with the specified maximum temperature value.

In particular, the second comparator sends the second comparator signal. In particular, the second comparator sends the second comparator signal to the linear regulators. In particular, the second comparator sends the second comparator signal when the temperature value is greater than or equal to the predetermined maximum temperature value.

In particular, the respective linear regulators adjust the respective operating voltages according to the second comparator signal.

In particular, the respective linear regulators reduce the respective operating voltages when the temperature value is greater than or equal to the specified maximum temperature value.

1. a. Erfassen eines jeweiligen zweiten Messwerts für einen jeweiligen Spannungsabfall über die jeweiligen Linearregler der Mehrzahl von Linearreglern;
2. b. Bilden eines jeweiligen Differenzwerts aus der Eingangsspannung der Linearregler und dem jeweiligen zweiten Messwert;
3. c. Vergleichen der jeweiligen Differenzwerte mit den jeweiligen vorgegebenen Mindestwerten für die jeweiligen Betriebsspannungen;
4. d. Vergleichen der jeweiligen Differenzwerte mit den jeweiligen vorgegebenen Maximalwerten für die jeweiligen Betriebsspannungen;
5. e. Senden eines dritten Komparator-Signals, und
6. f. Einstellen der Eingangsspannung entsprechend des dritten Komparator-Signals,

wobei das Verfahren iterativ durchgeführt wird.In one embodiment, the second control loop comprises the following process steps:

1. a. detecting a respective second measured value for a respective voltage drop across the respective linear regulators of the plurality of linear regulators;
2. b. Forming a respective difference value from the input voltage of the linear regulators and the respective second measured value;
3. c. comparing the respective difference values with the respective specified minimum values for the respective operating voltages;
4. d. comparing the respective difference values with the respective specified maximum values for the respective operating voltages;
5. e. Sending a third comparator signal, and
6. f. Adjusting the input voltage according to the third comparator signal,

where the procedure is carried out iteratively.

In particular, a second detector detects the respective second measured value for the respective voltage drop across the respective linear regulators. In particular, the second detector detects a first second measured value for a first linear regulator. In particular, the second detector detects a second second measured value for a second linear regulator. In particular, the second detector detects a third second measured value for a third linear regulator. In particular, the second detector detects a fourth second measured value for a fourth linear regulator.

In particular, a third comparator forms the respective difference value from the input voltage of the linear regulators and the respective second measured value. In particular, the third comparator forms a first difference value from the input voltage of the linear regulators and the first second measured value. In particular, the third comparator forms a second difference value from the input voltage of the linear regulators and the second second measured value. In particular, the third comparator forms a third difference value from the input voltage of the linear regulators and the third second measured value. In particular, the third comparator forms a fourth difference value from the input voltage of the linear regulators and the fourth second measured value.

In particular, the third comparator compares the respective difference values with the respective specified minimum values for the respective operating voltages.

In particular, the third comparator compares the first difference value with the predetermined minimum value for the first operating voltage. In particular, the third comparator compares the second difference value with the predetermined minimum value for the second operating voltage. In particular, the third comparator compares the third difference value with the predetermined minimum value for the third operating voltage. In particular, the third comparator compares the fourth difference value with the predetermined minimum value for the fourth operating voltage. In particular, the third comparator compares the respective difference values with the respective predetermined maximum values for the respective operating voltages.

In particular, the third comparator compares the first difference value with the predetermined maximum value for the first operating voltage. In particular, the third comparator compares the second difference value with the predetermined maximum value for the second operating voltage. In particular, the third comparator compares the third difference value with the predetermined maximum value for the third operating voltage. In particular, the third comparator compares the fourth difference value with the predetermined maximum value for the fourth operating voltage.

In particular, the third comparator sends the third comparator signal to the switching regulator. In particular, the third comparator sends the third comparator signal if the respective difference value is less than or equal to the respective predetermined minimum value for the respective operating voltage. In particular, the third comparator sends the third comparator signal if the first difference value is less than or equal to the predetermined minimum value for the first operating voltage. In particular, the third comparator sends the third comparator signal if the second difference value is less than or equal to the predetermined minimum value for the second operating voltage. In particular, the third comparator sends the third comparator signal if the third difference value is less than or equal to the predetermined minimum value for the third operating voltage. In particular, the third comparator sends the third comparator signal if the fourth difference value is less than or equal to the predetermined minimum value for the fourth operating voltage.

In particular, the third comparator sends the third comparator signal if the respective difference value is greater than or equal to the respective specified maximum value for the respective operating voltage voltage. In particular, the third comparator sends the third comparator signal when the first difference value is greater than or equal to the predetermined maximum value for the first operating voltage. In particular, the third comparator sends the third comparator signal when the second difference value is greater than or equal to the predetermined maximum value for the second operating voltage. In particular, the third comparator sends the third comparator signal when the third difference value is greater than or equal to the predetermined maximum value for the third operating voltage. In particular, the third comparator sends the third comparator signal when the fourth difference value is greater than or equal to the predetermined maximum value for the fourth operating voltage.

In particular, the switching regulator sets the input voltage for the linear regulators according to the third comparator signal.

In particular, the switching regulator increases the input voltage for the linear regulators if at least one of the respective difference values is less than or equal to the predetermined minimum value for the respective operating voltage. In particular, the switching regulator increases the input voltage for the linear regulators if the first difference value is less than or equal to the predetermined minimum value for the first operating voltage. In particular, the switching regulator increases the input voltage for the linear regulators if the second difference value is less than or equal to the predetermined minimum value for the second operating voltage. In particular, the switching regulator increases the input voltage for the linear regulators if the third difference value is less than or equal to the predetermined minimum value for the third operating voltage. In particular, the switching regulator increases the input voltage for the linear regulators if the fourth difference value is less than or equal to the predetermined minimum value for the fourth operating voltage.

In particular, the switching regulator reduces the input voltage for the linear regulators if at least one of the respective difference values is greater than or equal to the predetermined maximum value for the respective operating voltage. In particular, the switching regulator reduces the input voltage for the linear regulators if the first difference value is greater than or equal to the predetermined maximum value for the first operating voltage. In particular, the switching regulator reduces the input voltage for the linear regulators if the second difference value is greater than or equal to the predetermined minimum value for the second operating voltage. In particular, the switching regulator reduces the input voltage for the linear regulators if the third difference value is greater than or equal to the predetermined maximum value for the third operating voltage. In particular, the switching regulator reduces the input voltage for the linear regulators if the fourth difference value is greater than or equal to the predetermined maximum value for the fourth operating voltage.

The control device according to the invention thus enables a simultaneous provision of a plurality of different operating voltages using a single switching regulator.

The different operating voltages are set by a plurality of linear regulators, whereby each of the linear regulators sets a voltage value for each of the plurality of operating voltages.

By means of the control device according to the invention, an overvoltage at the power sources which supply the LED groups with power is prevented by individually regulating the plurality of different operating voltages.

In particular, the linear regulators reduce DC/DC supply ripple, and thus also EMI effects and LED current interference, which cause color flickering.

The linear regulators can also be used at the same time to allow multiplexing of the LEDs, so that only one power source is used to supply an LED group in order to operate several LEDs in an LED group, whereby the LEDs in this LED group have at least some different colors from one another. By switching the linear regulators on and off and using the appropriate PWM duty cycles on the power source, each LED (R, G, B) in the LED group can be dimmed individually. For LED groups with LEDs of three different colors, two power sources can thus be saved for each LED group.

A particular advantage of the invention is that by combining several linear regulators with a switching regulator, the dimensions of the control device can be significantly reduced compared to the prior art. This results in a compact and cost-effective design.

Further advantageous embodiments, features and functions of the invention are explained in connection with the examples shown in the figures.

• 1 schematische Darstellung einer erfindungsgemäßen Ansteuervorrichtung; und
• 2 vereinfachte schematische Darstellung eines Verfahrens zur Reduzierung einer Verlustleistung.

This shows:

• 1 schematic representation of a control device according to the invention; and
• 2 simplified schematic representation of a method for reducing power loss.

1 shows a schematic representation of a control device 100 according to the invention.

The control device 100 is designed to control at least one LED group 200. Each LED group 200 comprises at least one LED 201, 202, 203.

In the 1 In the embodiment shown, each of the LED groups 200 comprises a plurality of LEDs 201, 202, 203, wherein each of the LEDs 201, 202, 203 emits light of a different color. In the embodiment shown in 1 In the example shown, each of the LED groups 200 comprises a first LED 201 which emits red light, a second LED 202 which emits green light, and a third LED 203 which emits blue light.

However, it is also possible for an LED group 200 to alternatively or additionally comprise at least one white LED.

It is also possible for the LED groups 200 to have a different number of LEDs 201, 202, 203.

It is also possible for an LED group 200 to have several LEDs 201, 202, 203 of the same color, i.e. several red LEDs, and/or several green LEDs and/or several blue LEDs and/or several white LEDs.

The control device 100 comprises a plurality of linear regulators 101 and a switching regulator 102. In the 1 In the embodiment shown, a power supply 103 is integrated into the control device 100. The control device 100 and the power supply 103 can also be two separate units.

The power supply 103 comprises a plurality of current sources IQ, which are switched by a plurality of pulse width modulation units PWM. Each of the pulse width modulation units PWM switches one of the current sources IQ by sending a PWM signal PWMS.

Each of the current sources IQ supplies a respective LED group 200 assigned to it with current in accordance with the received PWM signal PWMS.

According to the current intensity applied to the LEDs 201, 202, 203 of the respective LED group 200, a respective color temperature of the corresponding LED group 200 is set.

The LED groups 200 are supplied with a supply voltage VS via a supply line VL.

The switching regulator 102 regulates the supply voltage VS to a constant voltage value, which serves as the input voltage ES for the linear regulator 101.

To operate different colored LEDs 201, 202, 203, different minimum voltages are required for the respective operating voltages V1, V2, V3. Red LEDs require a significantly lower voltage than green LEDs and blue LEDs. White LEDs, on the other hand, require a minimum voltage that is comparable to the minimum voltage for blue LEDs.

To set a color-specific individual operating voltage V1, V2, V3, the control device 100 comprises a plurality of linear regulators 101a, 101b, 101c. Each of the linear regulators 101a, 101b, 101c sets a voltage value for a respective operating voltage V1, V2, V3 of the LEDs 201, 202, 203 of a respective color. A first linear regulator 101a sets a first operating voltage V1 for the first LEDs 201 (in this example for all red LEDs) of each of the LED groups 200. A second linear regulator 101b sets a second operating voltage V2 for the second LEDs 202 (in this example all green LEDs) of each of the LED groups 200. A third linear regulator 101c sets a third operating voltage V3 for the third LEDs 203 (in this example all blue LEDs) of each of the LED groups 200.

By means of the linear regulators 101a, 101b, 101c, three different operating voltages V1, V2, V3 are provided.

In an embodiment not shown, the control device comprises a fourth linear regulator which sets a fourth operating voltage for fourth LEDs of a fourth color, in particular for white LEDs.

The linear regulators 101a, 101b, 101c can also function as multiplexers.

The linear regulators 101 and the current sources IQ are each switched on and off by pulse width modulation units PWM so that each LED 201, 202, 203 (R, G, B) can be dimmed individually.

To ensure operation of the LEDs 201, 202, 203, the input voltage ES of the linear regulator 101 must be sufficiently high.

The switching regulator 102 regulates a value for the input voltage ES such that the input voltage ES minus a voltage drop across the respective linear regulators 101a, 101b, 101c corresponds at least to the respective minimum voltage for the respective operating voltage V1, V2, V3.

In particular, the switching regulator 102 sets a voltage value for the input voltage ES which, minus the voltage drop across the linear regulators 101a, 101b, 101c, corresponds to at least the largest of the minimum voltages for the operating voltages V1, V2, V3.

The voltage drop across the current sources IQ generates a power loss, which is converted into heat.

To prevent overheating, the voltage drop across the current sources IQ must be kept low.

In particular, the voltage drop across the current sources IQ should not exceed a specified value. In particular, the specified value for the voltage drop across the current sources IQ is approximately 0.5V.

In addition, the operating voltages V1, V2, V3 can be adjusted depending on a temperature value sent by a temperature sensor TS.

The temperature sensor TS can be integrated in the control device 100.

The temperature sensor TS monitors a temperature increase resulting from a voltage drop across the current sources IQ.

In order to ensure functionality of the control device 100, a certain temperature must not be exceeded.

The linear regulators 101a, 101b, 101c thus regulate the operating voltages V1, V2, V3 for the corresponding LEDs 201, 202, 203 as a function of a measured value for the voltage drop at the current sources and/or as a function of a measured value for a temperature.

This is accomplished via two interconnected control loops, as in 2 shown in a simplified manner.

It is possible to use a plurality of control devices 100 as in 1 shown, one after the other.

2 shows a simplified schematic representation of a method for reducing power loss by means of the 1 control device shown.

This procedure involves a first control loop R1 and a second control loop R2.

In the first control loop R1, a first detector D1 detects a first measured value M1 for the voltage drop across each of the current sources.

A first comparator K1 compares the first measured value M1 with a predetermined maximum value for the voltage drop.

If the first measured value M1 exceeds the specified maximum value, the first comparator K1 sends a corresponding first comparator signal KS1a to the linear regulator 101.

Upon receipt of the first comparator signal KS1a, the respective linear regulator 101a, 101b, 101c reduces the respective operating voltage V1, V2, V3.

In particular, the first linear regulator 101a reduces the first operating voltage V1 if the first measured value M1 exceeds the predetermined maximum value when the first LEDs 201 are controlled.

In particular, the second linear regulator 101b reduces the second operating voltage V2 if the first measured value M1 exceeds the predetermined maximum value when the second LEDs 202 are controlled.

In particular, the third linear regulator 101c reduces the third operating voltage V3 if the first measured value M1 exceeds the predetermined maximum value when the third LEDs 203 are controlled.

Furthermore, the first comparator K1 compares the respective operating voltages V1, V2, V3 with a respective predetermined minimum value for the operating voltages V1, V2, V3, which is necessary to ensure the operation of the respective LEDs.

If one or more of the operating voltages V1, V2, V3 is equal to or below the respective specified minimum value for the respective operating voltages V1, V2, V3, the first Comparator K1 sends a corresponding second first comparator signal KS1b to the linear regulators 101. The first comparator K1 further compares the respective operating voltages V1, V2, V3 with a respective predetermined maximum value for the operating voltages V1, V2, V3.

If one or more of the operating voltages V1, V2, V3 corresponds to or exceeds the respective predetermined maximum value for the respective operating voltages V1, V2, V3, the first comparator K1 sends a corresponding second first comparator signal KS1b to the linear regulators 101. Upon receipt of the second first comparator signal KS1b, the respective linear regulator 101a, 101b, 101c increases or decreases the respective operating voltage V1, V2, V3 according to the second first comparator signal KS1b.

Here, the first linear regulator 101a increases the first operating voltage V1 if the first operating voltage V1 is less than or equal to the predetermined minimum value for the first operating voltage V1. If the first operating voltage V1 is greater than or equal to the predetermined maximum value for the first operating voltage V1, the first linear regulator 101a reduces the first operating voltage V1.

Equivalently, the second linear regulator 101b increases the second operating voltage V2 if the second operating voltage V2 is less than or equal to the predetermined minimum value for the second operating voltage V2. If the second operating voltage V2 is greater than or equal to the predetermined maximum value for the second operating voltage V2, the second linear regulator 101b decreases the second operating voltage V2.

Likewise, the third linear regulator 101c increases the third operating voltage V3 if the third operating voltage V3 is less than or equal to the predetermined minimum value. If the third operating voltage V3 is greater than or equal to the predetermined maximum value for the third operating voltage V3, the third linear regulator 101c reduces the third operating voltage V3.

Additionally or alternatively, the operating voltages V1, V2, V3 can be adjusted depending on a temperature value TW.

For this purpose, a temperature sensor TS records a temperature value TW of the current sources.

A second comparator K2 compares the temperature value TW transmitted by the temperature sensor TS with a specified maximum temperature value.

If the temperature value TW is greater than or equal to the specified maximum temperature value, the second comparator K2 sends a second comparator signal KS2 to the linear regulator 101.

When the linear regulators 101 receive the second comparator signal KS2, the linear regulators 101 reduce the operating voltages V1, V2, V3.

In a further embodiment, the second comparator K2 is integrated in the first comparator K1, so that the first comparator K1 compares the temperature value TW with the predetermined maximum temperature value and the first comparator K1 sends the second comparator signal KS2 to the linear regulator 101 if the temperature value TW is greater than or equal to the maximum temperature value.

In the second control loop R2, a second detector D2 detects a second measured value M2 for a respective voltage drop across the linear regulators 101.

Here, the second detector D2 detects a first second measured value M2a for the voltage drop across the first linear regulator 101a, a second second measured value M2b for the voltage drop across the second linear regulator 101b and a third second measured value M2c for the voltage drop across the third linear regulator 101c.

A third comparator K3 forms a difference between the second measured value M2 and the input voltage ES.

The third comparator K3 compares the resulting difference values for the respective linear regulators 101a, 101b, 101c with a respective predetermined minimum value for the respective operating voltages V1, V2, V3.

In the event that the respective difference value is less than or equal to the respective predetermined minimum value for the respective operating voltage V1, V2, V3, the third comparator K3 sends a corresponding third comparator signal KS3 to the switching regulator 102.

Furthermore, the third comparator K3 compares the difference values for the respective linear regulators 101a, 101b, 101c with a respective predetermined maximum value for the respective operating voltages V1, V2, V3.

In the event that the respective difference value is greater than or equal to the respective specified maximum value for the respective operating voltage V1, V2, V3, the third comparator K3 sends a corresponding corresponding third comparator signal KS3 to the switching regulator 102.

In an embodiment not shown, the third comparator can also be integrated in the first comparator or in the second comparator, so that the first comparator or second comparator forms the difference of the second measured value from the input voltage and sends the third comparator signal.

If the switching regulator 102 receives the third comparator signal KS3, the switching regulator 102 increases or decreases the input voltage ES according to the third comparator signal KS3 until each of the difference values is greater than or equal to the respective corresponding predetermined minimum value and at the same time less than or equal to the respective corresponding predetermined maximum value for the respective operating voltage V1, V2, V3.

The switching regulator 102 thus sets a voltage value for the input voltage ES at the linear regulators 101, which, minus the voltage drop across the linear regulators 101a, 101b, 101c, corresponds to at least the largest voltage value necessary for the operating voltages V1, V2, V3 of the LEDs 201, 202, 203, but at the same time does not exceed a maximum value for this operating voltage V1, V2, V3.

In this way, the second control circuit R2 ensures that the respective operating voltages V1, V2, V3 are sufficiently high at all times to supply the operation of the LEDs 201, 202, 203 of the respective color with sufficient voltage.

The control device according to the invention thus enables a simultaneous provision of a plurality of different operating voltages using a single switching regulator.

The different operating voltages are set by a plurality of linear regulators, whereby each of the linear regulators sets a voltage value for each of the plurality of operating voltages.

By means of the control device according to the invention, an overvoltage at the power sources which supply the LED groups with power is prevented by individually regulating the plurality of different operating voltages.

By combining several linear regulators with a switching regulator, which provides a constant voltage value for an input voltage of the linear regulators, the dimensions of the control device can be significantly reduced compared to the state of the art.

In particular, the linear regulators reduce DC/DC supply ripple, and thus also EMI effects and LED current interference, which cause color flickering.

List of reference symbols

100

Control device

101

Linear regulator

101a

first linear regulator

101b

second linear regulator

101c

third linear regulator

102

Switching regulator

103

Power supply

200

LED group

201

first LED

202

second LED

203

third LED

VL

Supply line

US

Supply voltage

V1

first operating voltage

V2

second operating voltage

V3

third operating voltage

IQ

Power source

PWM

Pulse width modulation unit

PWM

PWM signal

R1

first control loop

R2

second control loop

D1

first detector

D2

second detector

M1

first measured value

M2

second measured value

M2a

first second measured value

M2b

second second measured value

M2c

third second measured value

TS

Temperature sensor

TW

Temperature value

K1

first comparator

K2

second comparator

K3

third comparator

KS1

first comparator signal

KS1a

first first comparator signal

KS1b

second first comparator signal

KS2

second comparator signal

KS3

third comparator signal

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 8319449 B2 [0007, 0008, 0010]

Claims (15)

Control device (100) for controlling at least one LED group (200) comprising at least one LED (201, 202, 203), wherein the control device (100) comprises a switching regulator (102), and wherein the control device (100) is designed to provide a plurality of operating voltages (V1, V2, V3), characterized in that the control device (100) comprises a plurality of linear regulators (101), wherein each of the linear regulators (101a, 101b, 101c) is designed to individually set an operating voltage (V1, V2, V3) of the plurality of operating voltages (V1, V2, V3). Control device (100) according to Claim 1 , characterized in that the control device (100) comprises a first control loop (R1) and a second control loop (R2). Control device (100) according to Claim 2 , characterized in that the first control circuit (R1) comprises the linear regulators (101a, 101b, 101c), wherein the first control circuit (R1) is designed to set the plurality of operating voltages (V1, V2, V3) by means of the linear regulators (101a, 101b, 101c) such that the operating voltages (V1, V2, V3) are at least partially different from one another. Control device (100) according to one of the Claims 2 until 3 , characterized in that the second control circuit (R2) comprises the switching regulator (102), wherein the second control circuit is adapted to set an input voltage (ES) for the linear regulators (101) by means of the switching regulator (102). Control device (100) according to one of the preceding claims, characterized in that the at least one LED group (200) comprises a plurality of LEDs (201, 202, 203). Control device (100) according to Claim 5 , characterized in that each LED (201, 202, 203) of the plurality of LEDs (201, 202, 203) of the at least one LED group (200) has the same color. Control device (100) according to one of the Claims 5 until 6 , characterized in that the plurality of LEDs (201, 202, 203) of the at least one LED group (200) have at least two different colors. Control device (100) according to one of the preceding claims, characterized in that the control device (100) is designed to supply LEDs (201, 202, 203) of different colors with mutually different operating voltages (V1, V2, V3), wherein a first linear regulator (101a) is designed to set a first operating voltage (V1), and wherein a second linear regulator (101b) is designed to set a second operating voltage (V2) different from the first operating voltage (V1). Control device (100) according to one of the preceding claims, characterized in that the control device (100) comprises at least one current source (IQ), wherein the at least one current source (IQ) is configured to supply the at least one LED group (200) with current. Control device (100) according to one of the preceding claims, characterized in that the linear regulators (101) are designed as multiplexers. Control device (100) according to one of the Claims 9 or 10 , characterized in that the control device comprises at least one pulse width modulation unit (PWM), wherein the at least one pulse width modulation unit (PWM) is designed to switch the at least one current source (IQ), and/or wherein the at least one pulse width modulation unit (PWM) is designed to assign the linear regulators (101a, 101b, 101c) of the plurality of linear regulators (101) individually and separately from one another with a PWM duty cycle. Method for setting a plurality of operating voltages (V1, V2, V3) that differ at least in part from one another by means of a control device (100) according to one of the preceding claims, wherein a first control circuit (R1) of the control device (100) sets a plurality of operating voltages (V1, V2, V3) by means of a plurality of linear regulators (101a, 101b, 101c), and wherein a second control circuit (R2) sets an input voltage (ES) for the linear regulators (101a, 101b, 101c). Procedure according to Claim 12 , characterized in that the first control loop (R1) comprises the following method steps: a. Detecting a first measured value (M1) for a Voltage drop across at least one current source (IQ); b. Comparing the first measured value (M1) with a predetermined maximum value for the voltage drop across the at least one current source (IQ); c. Sending a first first comparator signal (KS1a); d. Setting a respective operating voltage (V1, V2, V3) for each of the plurality of operating voltages (V1, V2, V3) according to the first first comparator signal (KS1a); e. Comparing the respective operating voltage (V1, V2, V3) with a predetermined minimum value for the respective operating voltages (V1, V2, V3); f. Comparing the respective operating voltages (V1, V2, V3) with a predetermined maximum value for the respective operating voltages (V1, V2, V3); g. Sending a second first comparator signal (KS1b); and h. Setting a respective operating voltage (V1, V2, V3) for each of the plurality of operating voltages (V1, V2, V3) according to the second first comparator signal (KS1b), wherein the method is carried out iteratively. Procedure according to one of the Claims 12 until 13 , characterized in that the first control loop (R1) comprises the following method steps: a. detecting a temperature value (TW) of the at least one current source (IQ); b. comparing the temperature value (TW) with a predetermined maximum temperature value; c. sending a second comparator signal (KS2), and d. setting the respective operating voltages (V1, V2, V3) according to the second comparator signal (KS2), wherein the method is carried out iteratively. Procedure according to one of the Claims 12 until 14 , characterized in that the second control loop (R2) comprises the following method steps: a. detecting a respective second measured value (M2a, M2b, M2c) for a respective voltage drop across the respective linear regulators (101a, 101b, 101c) of the plurality of linear regulators (101); b. forming a respective difference value from the input voltage (ES) of the linear regulators (101) and the respective second measured value (M2a, M2b, M2c); c. comparing the respective difference values with the respective predetermined minimum values for the respective operating voltages (V1, V2, V3); d. comparing the respective difference values with the respective predetermined maximum values for the respective operating voltages (V1, V2, V3); e. sending a third comparator signal (KS3), and f. setting the input voltage (ES) according to the third comparator signal (KS3), wherein the method is carried out iteratively.

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