DE102013111510A1 - Circuit and method for driving LEDs - Google Patents

Abstract

The invention relates to a circuit (100) for driving LEDs (11, 21), comprising: - a parallel circuit part (101) having a first and second strand (10.1, 20.1), - first connection points (10.1) in the first strand (10.1) 1.1, 1.2) for a first LED row (10) with a first LED (11), - in the second string (20.1) second connection points (2.1, 2.2) for a second LED row (20) with a second LED ( 21), - in the first strand (10.1) a first resistor (111) and - in the first strand (10.1) a first switch (115), wherein the first switch (115) and the first resistor (111) a first resistance circuit (110) representing an LED bias resistor switchable between at least two values enabling current to flow through the resistor circuit (110). Moreover, the invention relates to a lighting system with such a circuit and a method for driving LEDs

Description

The invention relates to a circuit and a method for controlling LEDs, in particular an LED array, in particular in the field of vehicle lighting.

The DE 10 2006 005 521 B3 shows a drive circuit and a method for driving an LED array, wherein the LED array has a voltage source, a regulator unit and at least two parallel strands, each having at least one LED, further provided in each of the strands a controllable by the controller unit switch and the switches of at least two strings are independently controllable by the controller unit.

The object underlying the invention was to improve the known in the art driving of LEDs.

• – einen Parallelschaltungsteil (101) mit einem ersten und zweiten Strang (10.1, 20.1),
• – in dem ersten Strang (10.1) erste Anschlusspunkte (1.1, 1.2) für eine erste LED-Reihe (10) mit einer ersten LED (11),
• – in dem zweiten Strang (20.1) zweite Anschlusspunkte (2.1, 2.2) für eine zweite LED-Reihe (20) mit einer zweiten LED (21),
• – in dem ersten Strang (10.1) einen ersten Widerstand (111) und
• – in dem ersten Strang (10.1) einen ersten Schalter (115),

wobei der erste Schalter (115) und der erste Widerstand (111) eine erste Widerstandsschaltung (110) bilden, die einen LED-Vorwiderstand darstellt, der zwischen mindestens zwei Werten schaltbar ist, die einen Stromfluss durch die Widerstandsschaltung (110) ermöglichen. The object is achieved according to the invention by, in particular, a circuit ( 100 ) for driving LEDs ( 11 . 21 ), which has:

• A parallel circuit part ( 101 ) with a first and second strand ( 10.1 . 20.1 )
• - in the first strand ( 10.1 ) first connection points ( 1.1 . 1.2 ) for a first LED row ( 10 ) with a first LED ( 11 )
• In the second strand ( 20.1 ) second connection points ( 2.1 . 2.2 ) for a second LED row ( 20 ) with a second LED ( 21 )
• - in the first strand ( 10.1 ) a first resistor ( 111 ) and
• - in the first strand ( 10.1 ) a first switch ( 115 )

the first switch ( 115 ) and the first resistor ( 111 ) a first resistance circuit ( 110 ), which is an LED series resistor, which is switchable between at least two values, the current flow through the resistor circuit ( 110 ) enable.

The object is further achieved according to the invention by, in particular, a method for driving LEDs ( 11 . 21 ), with a first LED ( 11 ) and a second LED ( 21 ) by means of a parallel connection with a first and second strand ( 10.1 . 20.1 ) are connected in parallel and energized, wherein a LED series resistor, by a resistor circuit ( 110 ) with a first switch ( 115 ) and a first resistor ( 111 ) in the first strand ( 10.1 ) is switched between at least two values, which is a current flow through the resistor circuit ( 110 ) enable.

This makes it possible, in particular, to mitigate or, if possible, compensate for the negative effect of manufacturing tolerances of LEDs, which lead to different forward voltages, by switching over an LED series resistor. Today LEDs can be provided in a flux voltage tolerance with the same brightness class of +/- 0.2V. In a worst case scenario, an absolute difference in the forward voltage of 0.4 V would occur with two parallel LEDs, each with a series resistor. There is a risk that the LED with the lower forward voltage could be overloaded. Particularly in the case of more than one series-connected LED in one line, the forward voltage tolerances add up, so that in the worst case, e.g. (only) four series-connected LEDs of a string could (already) have an absolute difference of 1.6 V between two strings. By means of the switchable by means of the switch resistor is thus a higher series resistance in the strand of the LED (s) with the lower (total) forward voltage as compensating element adjustable. Thus, damage to the LED (s) in the strand with the lower (total) forward voltage is prevented.

A parallel circuit part is preferably the subregion of the circuit which has two, preferably more than two, strings connected in parallel, wherein in each case one LED row can be switched into the strings. Preferably, a single line leads into the parallel circuit part, starting from one pole of a voltage and / or current source, and a further single line leads out of the parallel circuit part to the other pole of the voltage and / or current source.

The strands are preferably the parallel paths of the parallel connection. They preferably branch off from a single line incoming into the parallel circuit part. Preferably, a common connection point as the end point of the individual line for the anodes or the cathodes of the parallel-connected LEDs forms the beginning of the parallel branching. The strands are preferably brought together again at a single line emanating from the parallel circuit part.

An LED row preferably consists of already one LED, particularly preferably a series connection of several LEDs.

The resistance circuit is preferably a subcircuit in a string. In the case of a connected LED row, it is preferably connected in series with the LED row. It preferably has two poles.

Values that allow current to flow through the resistor circuit are preferably values at which current flow occurs at an applied voltage; they preferably do not include open circuit (resistance = ∞). Preferably, the resistance circuit in each switching state of the first switch allows a current flow through the resistance circuit, more preferably, it has no idle between the poles of the resistance circuit in any switching state of the switch.

The LED series resistor is preferably the ohmic resistance of the resistance circuit, preferably between the poles of the resistance circuit. The resistance is determined by the combination of the first resistor and the first switch of the resistance circuit (with). Preferably, the LED series resistor takes only values R in the range of R> = 0 Ω and R <∞ Ω, more preferably R> = 0 Ω and R <10 MΩ, most preferably R> = 1 Ω and R <10 kΩ , Preferably, at most one of the values to which the LED series resistor can be switched is equal to 0 Ω. The LED series resistor is preferably switchable to two, more preferably three, most preferably four values.

Preferably, the first switch of the first resistance circuit is connected in parallel with the first resistance of the first resistance circuit.

The switch is preferably a semiconductor switch, such as e.g. a (field effect) transistor, or a relay, each electronically, i. preferably by means of an electronic control signal, are switchable.

Preferred is a resistance mentioned in the application, e.g. the first resistor, also formed or formed by a series and / or parallel connection of two or more individual resistors.

Another circuit according to the invention ( 100 ) in the second strand ( 20.1 ) a first resistor ( 121 ) and a first switch ( 125 ), the first switch ( 125 ) of the second strand ( 20.1 ) and the first resistor ( 121 ) of the second strand ( 20.1 ) a second resistance circuit ( 120 ), which represents a LED series resistor, which is switchable between at least two values, which preferably a current flow through the second resistance circuit ( 120 ) enable. In a further method according to the invention, an LED series resistor is produced by a second resistance circuit ( 120 ) with a first switch ( 125 ) and a first resistor ( 121 ) in the second strand ( 20.1 ) is connected between at least two values, which preferably a current flow through the second resistance circuit ( 120 ) enable.

As a result, a higher flexibility of compensating flux voltage tolerances is achieved.

Preferably, the first switch of the second string is connected in parallel with the first resistor of the second string.

Preferably, the circuit in the parallel circuit part has a plurality of strings, e.g. more than two or more than three strands and in each strand it has a resistance circuit.

Another circuit according to the invention ( 100 ) in one of the existing resistance circuits ( 110 ) a switch resistor ( 115.1 ) in series with that in the resistance circuit ( 110 ) existing first switch ( 115 ) to that in the resistance circuit ( 110 ) existing first resistor ( 111 ) is connected in parallel.

As a result, at least two values of the LED series resistor can be achieved, which are greater than 0 Ω.

Another circuit according to the invention ( 100 ) in one of the existing resistance circuits ( 110 . 120 ) a second resistor ( 112 . 122 ) and a second switch ( 116 . 126 ), the second switch ( 116 . 126 ) to the second resistor ( 112 . 122 ) is connected in parallel.

As a result, at least three different values of the LED series resistor can be set in the corresponding resistance circuit.

In another circuit according to the invention ( 100 ) is an existing switch ( 115 . 116 . 125 . 126 ) with a control unit ( 200 ) and by means of this control unit ( 200 ) electronically switchable.

As a result, an adjustment of the LED series resistor can be automated. The control unit is e.g. a control IC or a microcomputer with at least one control output.

In another circuit according to the invention ( 100 ) is the control unit ( 200 ), a current in the first and / or second strand ( 10.1 . 20.1 ) and, depending on the measured current, an existing one, with the control unit ( 200 ) connected switches ( 115 . 116 . 125 . 126 ) to switch. In a further method according to the invention, by means of a control unit ( 200 ) a current through the first strand ( 10.1 ) and the first switch ( 115 ) is switched depending on the measured current.

As a result, a diagnostic phase can be carried out, in which first the sum of the forward voltages in a string can be measured. For example, For example, the circuit has in each string a preferably switchable current meter (i.e., for example, a sense resistor connected in parallel with a voltmeter). Particularly preferably, the circuit has a switch and an ammeter and the strands are individually switched to the ammeter by means of the switch.

Preferably, the Flussspannungsunterschiede between the individual LED rows of strands can be determined by the control unit. With particular regard to the measured current, taking into account the available, adjustable LED series resistor values, it is possible to determine a series resistance of the LED series resistors in the individual strings that optimally compensates for the flux voltage tolerance differences. Preferably, control commands reaching this combination can be sent to the switches.

Another circuit according to the invention ( 1 ) in the first strand ( 10.1 ) in series with the resistance circuit ( 110 ) on a dimmer switch.

This allows an even more flexible control.

A dimming switch is preferably a switch by means of which the voltage and / or the current through a string is adjustable. Particularly preferably, the dimming switch is a PWM-driven switching element. Particularly preferably, each strand has a dimming switch.

The object is achieved in particular by a lighting system having a circuit according to the invention ( 100 ), the first LED row ( 10 ) with the first LED ( 11 ) at the first connection points ( 1.1 . 1.2 ) and the second LED row ( 20 ) with the second LED ( 21 ) at the second connection points ( 2.1 . 2.2 ) connected.

As a result, a lighting system is possible in which in particular the negative effect of flux voltage tolerances of the LEDs used can be mitigated or possibly compensated.

Embodiments of the invention are explained below with reference to the drawings.

Show it:

1 a circuit according to the invention,

2 a circuit based on the circuit in 1 in addition to a second resistance circuit,

3 a circuit based on the circuit in 1 in addition to a series resistor connected in series with the first switch of the first resistance circuit,

4 a circuit based on the circuit in 2 in addition each having a second switch and a second resistor in a resistor circuit,

5 a circuit based on the circuit in 4 wherein an alternative second resistance circuit and a switchable by a control unit first switch of the first resistance circuit is shown and

6 a lighting system according to the invention with a circuit according to the invention based on 2 ,

1 shows a circuit according to the invention 100 , It has a parallel circuit part 101 (for the sake of clarity only in 1 marked) with two parallel strands 10.1 and 20.1 on. They branch off at the first connection point 1.1 for a first LED row 10 with a first LED 11 and the second connection point 2.1 for a second LED row with a second LED 21 from each other. The first and second connection point 1.1 and 2.1 are a common connection point. The further first connection point 1.2 and the other second connection point 2.2 are separated from each other, the other first connection point 1.2 lies in the first strand 10.1 and the other second connection point 2.2 in the second strand 20.1 , To the first connection points 1.1 . 1.2 is an LED series 10 connectable and to the second connection points 2.1 . 2.2 a second LED row 20 Eg, as shown here, with the anodes at the common connection point 1.1 . 1.2 Alternatively, the cathodes of the LED rows are at the common connection point 1.1 . 1.2 connected. An LED series 10 respectively. 20 consists of at least one LED as shown here 11 respectively. 21 or several LEDs connected in series. The first strand 10.1 has a first resistance circuit 110 on, which has a LED resistor in the first strand 10.1 for the first LED row 10 represents, which is switchable between at least two values. Here is the resistor circuit 110 a first resistance 111 in parallel with a first switch 115 on. After the resistance circuit 110 are the strands 10.1 , and 20.1 merged again. Furthermore, the circuit has fifth connection points 5.1 . 5.2 for a voltage and / or current source connected in series with the parallel circuit part 101 are switched.

In operation of the circuit 100 will be for the first LED series 10 a LED dropping resistor through the resistor circuit 110 with the first switch 115 and the first resistance 111 in the first strand 10.1 is formed, switched between two values. When the switch 115 is open, is the value of the first resistor 111 the value of the resistor through the circuit 110 formed LED series resistor. Is the switch 115 closed, so is the first resistance 111 bridged and results in a value of the LED series resistor to 0 Ω.

This is the series resistor of an LED row 10 by means of a switch 115 customizable. It can thus be reacted to any flow stress tolerances. The circuit is flexible to different concrete LED rows 10 or 20 customizable with their specific manufacturing tolerance.

2 shows a circuit 100 building on the circuit 100 in 1 , additionally with a second resistance circuit 120 , which has a LED resistor in the second strand 20.1 for the second LED row 20 represents, which is switchable between at least two values. It has a first resistance 121 and a first switch connected in parallel thereto 125 on.

In operation of the circuit 100 takes the resistance circuit 120 with the switch closed 125 a value of 0 Ω as LED series resistor of the second LED row 20 on and with the switch open 125 the value of the resistance 121 ,

As a result, an even more flexible adaptation to tolerances of the LED rows 10 . 20 possible, as well as in the strand 20.1 a customizable LED resistor is realized.

3 shows a circuit 100 building on the circuit 100 in 1 , in addition to one with the first switch 115 the first resistance circuit 110 series-connected switchable resistor 115.1 ,

In operation of the circuit 100 takes the resistance circuit 110 with the switch closed 115 a value> 0 Ω as a LED series resistor, ie the value of the parallel circuit of switch resistor 115.1 and resistance 111 ,

As a result, two different LED series resistor values of greater than 0 Ω can be realized. In addition, here could be a second resistor circuit 120 as in 2 shown or in to the resistor circuit 110 analog version with a switch resistor in the strand 20.1 be inserted for greater flexibility of customization.

4 shows a circuit 100 building on the circuit 100 in 2 , in addition, each with a second switch 116 . 126 and a second resistor 112 . 122 in a resistance circuit 110 . 120 , The second resistances 112 . 122 are each connected in parallel with the second switches 115 . 126 , These parallel circuits are each connected in series with the parallel circuits of the first switch 115 . 125 and the first resistances 111 . 121 , The resistance circuits 110 . 120 can partially or continuously have circuit resistors, as in 3 is shown.

• – sind die Schalter 115, 116 geschlossen, ist der LED-Vorwiderstandswert 0 Ω.
• – sind die Schalter 115, 116 geöffnet, ist der LED-Vorwiderstandswert die Summe der Widerstandswerte der Widerstände 111, 112.
• – ist Schalter 115 geöffnet und Schalter 116 geschlossen, ist der LED-Vorwiderstandswert der Wert des Widerstands 111
• – ist Schalter 116 geöffnet und Schalter 115 geschlossen, ist der LED-Vorwiderstandswert der Wert des Widerstands 112.

In operation of the circuit 100 are the resistance circuits 110 . 120 able to accept four different LED resistor values each. Exemplary for resistance switching 110 :

• - are the switches 115 . 116 closed, the LED series resistance value is 0 Ω.
• - are the switches 115 . 116 opened, the LED Vorwiderstandswert is the sum of the resistance values of the resistors 111 . 112 ,
• - is switch 115 opened and switch 116 closed, the LED series resistance value is the value of the resistor 111
• - is switch 116 opened and switch 115 closed, the LED series resistance value is the value of the resistor 112 ,

This achieves an even further increase in the flexibility of adaptation of LED series resistors.

5 shows a circuit 100 building on the circuit 100 in 4 wherein an alternative embodiment of a second resistor circuit 120 as well as through a control unit 200 switchable first switch 115 the first resistance circuit 110 is shown. The resistance circuit 120 has a parallel connection, wherein in the one parallel strand of the first resistor 121 with the second switch 126 is connected in series and in the second parallel string of the second resistor 122 with the first switch 125 is connected in series. The first switch 115 the first resistance circuit 110 Here is a bipolar transistor whose base pole with a first Vorwiderstandsschaltausgang 215 the control unit 200 connected is. It is also possible to use another semiconductor switch or a relay. The switches are also preferred 116 . 125 and 126 each with a switching output of the control unit 200 connected. Furthermore, the circuit 100 set up to measure the flow of current in a string. A first voltmeter 105 that leads to a measuring resistor 107 is connected in parallel, is connected in series with the parallel circuit part. strand 10.1 has a first measuring switch 102 , Strand 20.1 a second measuring switch 103 on. A third measuring switch 104 is parallel to the first voltmeter 105 and the measuring resistor 107 connected. At a first fair entrance 205 is the first voltmeter 105 , at a third switching output 204 the third measuring switch 104 , at a second switching output 203 the second measuring switch 103 and at a first switching output 202 the first measuring switch 102 connected. Furthermore, the control unit 200 set up, a supply voltage of the LED rows 10 . 20 to eat. This is a second voltmeter 106 the connection points 1.1 . 2.1 connected and at a second measuring input 206 the control unit 200 , The function of the measuring switch is preferred 103 a blocking of the flow of current through the second strand 20.1 from the counters 125 . 126 taken, which then the measuring switch 103 replace. The measuring switches 102 . 103 and 104 form a switch with which the ammeter (measuring resistor 107 and voltmeter 105 ) in a strand 10.1 . 20.1 is switchable. As an alternative to the construction by means of a switch, each strand has its own ammeter 105 on.

In operation of the circuit 100 is with connected LED rows 10 . 20 and connected voltage and / or current source, first the current in the first strand 10.1 measured. For this purpose, the second measuring switch 103 and third measuring switches 104 opened and the first measuring switch 102 closed and the on the measuring resistor 107 decreasing voltage measured. The switch position 115 . 116 as well as the resistance values 111 and 112 are known. Subsequently, the current in the second Stang 20.1 measured by the first measuring switch 102 and third measuring switches 104 opened and the second measuring switch 103 be closed and the on the measuring resistor 107 decreasing voltage is measured. The switch position 125 . 126 as well as the resistance values 121 and 122 are known. At least one of the switches 125 . 126 is closed. In parallel, the voltage is preferred by means of the voltmeter 106 measured. Depending on the measured voltages and indirectly measured currents, the switch 115 closed or opened. Subsequently, the third measuring switch 104 closed to the voltmeter and the measuring resistor 107 to bridge. Preferably, such opening / closing and the switch takes place 125 . 126 and 116 by means of the control unit 200 ,

This is with the aid of a control unit 200 an automated measurement of flux voltage tolerances of the used LED-series 10 . 20 measurable and an adaptation of the LED series resistors by eg the switch 115 can also be automated.

6 shows a lighting system according to the invention with a circuit according to the invention 100 Based on 2 , The circuit 100 has a parallel circuit part with four strings 10.2 . 20.1 . 30.1 and 40.1 on which LED rows 10 . 20 . 30 . 40 with four LEDs each 11 . 12 . 13 . 14 such as 21 . 22 . 23 . 24 such as 31 . 32 . 33 . 34 such as 41 . 42 . 43 . 44 via connection points 1.1 . 1.2 such as 2.1 . 2.2 such as 3.1 . 3.2 such as 4.1 . 4.2 are connected. In the first two strands 10.1 and 20.1 are resistance circuits 110 and 120 present, the first resistance circuit 110 with a first resistance 111 and a second resistor 112 and a first switch 115 , which bridges these two resistors in parallel, the second resistance circuit 120 with a first resistance 121 and a first switch connected in parallel thereto 125 and another resistor connected in series with both 122 , The third and fourth strand 30.1 and 40.1 have only constant series resistors 131 . 132 such as 141 . 142 It is also possible that both or at least one strand also has a resistance circuit with a switch and a resistor plus or as an alternative to the existing series resistors. At the fifth connection points is a power source 50 connected. In each strand, visualizing the effect of the flux voltage tolerance is a virtual voltage difference 15 . 25 . 35 and 45 located. Alternatively, a switch or more than one switch can be used in a string. Furthermore, in contrast to the exemplary interconnection, the resistors 111 . 112 be arranged in parallel instead of in series. The switches can completely bridge the resistors once (see strand 10.1 ) or parts thereof (see strand 20.1 ).

It is now assumed that a worst case scenario with respect to the flux voltage tolerances of the LEDs. In the strand 40.1 There are four LEDs with a forward voltage tolerance of -0.2 V each, so together a difference of -0.8 V represented by the voltage difference 45 , In the strand 10.1 There are four LEDs with a tolerance of +0.2 V, so together a difference of +0.8 V represented by voltage difference 15 , Each string contains series resistances of 0.2 R (R = eg 50 mΩ). The nominal current of the diodes of 1.5 A is in the string 10.1 (see LED 14 ). In the other strands arise due to the self adjusting flux voltage of strand 10.1 , which is the highest forward voltage of all strings, correspondingly higher currents. The highest current, here 3.1 A (see LED 44 ), is in line 40.1 a, because here are the LEDs 41 . 42 . 43 and 44 with the lowest forward voltage. In the case of the type of LED used here, this current far exceeds their load capacity. In detail, the following operating states result (U = voltage, I = current), see 2nd and 3rd column: switch 115 and 125 open switch 115 and 125 to component U / V I / O U / V I / O voltage difference 45 -0.8 3.1 -0.8 1.9 voltage difference 35 0.3 2.5 0.3 1.6 voltage difference 25 -0.3 2 -0.3 1.5 voltage difference 15 -0.8 1.5 -0.8 1.5 diode 44 3.5 3.1 3.3 1.9 diode 43 3.5 3.1 3.3 1.9 diode 42 3.5 3.1 3.3 1.9 diode 41 3.5 3.1 3.3 1.9 diode 34 3.4 2.5 3.2 1.6 diode 33 3.4 2.5 3.2 1.6 diode 32 3.4 2.5 3.2 1.6 diode 31 3.4 2.5 3.2 1.6 diode 24 3.3 2 3.2 1.5 diode 23 3.3 2 3.2 1.5 diode 22 3.3 2 3.2 1.5 diode 21 3.3 2 3.2 1.5 diode 14 3.2 1.5 3.2 1.5 diode 13 3.2 1.5 3.2 1.5 diode 12 3.2 1.5 3.2 1.5 diode 11 3.2 1.5 3.2 1.5 resistance 142 0.3 3.1 0.6 1.9 resistance 141 0.3 3.1 0.6 1.9 resistance 132 0.3 2.5 0.5 1.6 resistance 131 0.3 2.5 0.5 1.6 resistance 122 0.2 2 0.4 1.5 resistance 121 0.2 2 0 0 resistance 112 0.2 1.5 0 0 resistance 111 0.2 1.5 0 0 switch 125 0.2 0 0 1.5 switch 115 0.4 0 0 1.5 power source 13.8 9.1 13.5 6.5

To damage the LEDs in the strand 40.1 to avoid, now the switches are closed. This will cause the voltage drops across the resistors 111 . 112 in the case of the switch 115 as well as the resistance 121 in the case of the switch 125 switched off (0 V) and the corresponding string voltage, which is decisive for the system, is lowered. Thereupon turns on the other strands 40.1 and 30.1 also a lower voltage, which has the consequence that adjust correspondingly lower currents there. The operating states are indicated in the already mentioned table in the fourth and fifth column.

Through this interconnection, the power is in the strand 40.1 from 3.1A to 1.9A, which in this case is within the operating limits of the type of LED used. Furthermore, the power source is needed 50 can not deliver as before 9.1 A, but only 6.5 A, which is very close to the required rated current of 4 × 1.5 A and thus is more efficient.

With this invention, a circuit is provided by means of which an adaptation of forward voltage tolerances of parallel-connected LEDs or LED rows is made possible in a simple manner. Switching between at least two different resistance values of the corresponding resistance circuit is possible by means of an adjustable resistance circuit connected in series with an LED or an LED row as a LED series resistor. For this purpose, the resistance circuit preferably has at least one switch and a resistor in parallel. Each strand preferably has an adjustable resistance circuit.

LIST OF REFERENCE NUMBERS

1.1, 1.2

first connection points for first LED row

2.1, 2.2

second connection points for second LED row

3.1, 3.2

third connection points for third LED row

4.1, 4.2

fourth connection points for fourth LED row

5.1, 5.2

fifth connection points for voltage and / or current source

10

first LED row

10.1

first strand

11

first LED

12, 13, 14

further LEDs of the first LED row

15

Voltage difference due to the flux voltage inaccuracy

20

second LED row

20.1

second strand

21

second LED

22, 23, 24

additional LEDs of the second LED row

25

Voltage difference due to the flux voltage inaccuracy

30

third LED row

30.1

third strand

31

third LED

32, 33, 34

additional LEDs of the third LED row

35

Voltage difference due to the flux voltage inaccuracy

40

fourth LED row

40.1

fourth strand

41

fourth LED

42, 43, 44

additional LEDs of the fourth LED row

45

Voltage difference due to the flux voltage inaccuracy

50

Voltage and / or current source

100

Circuit for driving LEDs

101

Parallel connection part

102

first measuring switch

103

second measuring switch

104

third measuring switch

105

first voltmeter

106

second voltmeter

107

measuring resistor

110

first resistance circuit

111

first resistor of the first resistor circuit

112

second resistor of the first resistor circuit

115

first switch of the first resistance circuit

115.1

Schaltervorwiderstand

116

second switch of the first resistor circuit

120

second resistance circuit

121

first resistor of the second resistor circuit

122

second resistor of the second resistor circuit

125

first switch of the second resistance circuit

126

second switch of the second resistance circuit

131

first series resistor of the third strand

132

second series resistor of the third strand

141

first series resistor of the fourth strand

142

second series resistor of the fourth strand

200

control unit

202

first switching output

203

second switching output

204

third switching output

205

first fair entrance

206

second fair entrance

215

first series resistor switching output

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006005521 B3 [0002]

Claims (10)

Circuit ( 100 ) for driving LEDs ( 11 . 21 ), comprising: - a parallel circuit part ( 101 ) with a first and second strand ( 10.1 . 20.1 ), - in the first strand ( 10 .1) first connection points ( 1.1 . 1.2 ) for a first LED row ( 10 ) with a first LED ( 11 ), - in the second strand ( 20.1 ) second connection points ( 2.1 . 2.2 ) for a second LED row ( 20 ) with a second LED ( 21 ), - in the first strand ( 10.1 ) a first resistor ( 111 ) and - in the first strand ( 10.1 ) a first switch ( 115 ), characterized in that the first switch ( 115 ) and the first resistor ( 111 ) a first resistance circuit ( 110 ), which is an LED series resistor, which is switchable between at least two values, the current flow through the resistor circuit ( 110 ) enable. Circuit ( 100 ) according to claim 1, which is in the second strand ( 20.1 ) a first resistor ( 121 ) and a first switch ( 125 ), wherein the first switch ( 125 ) of the second strand ( 20.1 ) and the first resistor ( 121 ) of the second strand ( 20.1 ) a second resistance circuit ( 120 ), which represents a LED series resistor, which is switchable between at least two values. Circuit ( 100 ) according to one of the preceding claims, which in one of the existing resistance circuits ( 110 ) a switch resistor ( 115.1 ) in series with that in the resistance circuit ( 110 ) existing first switch ( 115 ) to that in the resistance circuit ( 110 ) existing first resistor ( 111 ) is connected in parallel. Circuit ( 100 ) according to one of the preceding claims, which in one of the existing resistance circuits ( 110 . 120 ) a second resistor ( 112 . 122 ) and a second switch ( 116 . 126 ), the second switch ( 116 . 126 ) to the second resistor ( 112 . 122 ) is connected in parallel. Circuit ( 100 ) according to one of the preceding claims, wherein an existing switch ( 115 . 116 . 125 . 126 ) with a control unit ( 200 ) and by means of this control unit ( 200 ) is electronically switchable. Circuit ( 100 ) according to claim 5, wherein the control unit ( 200 ) is set up a current in the first and / or second strand ( 10.1 . 20.1 ) and, depending on the measured current, an existing one, with the control unit ( 200 ) connected switches ( 115 . 116 . 125 . 126 ) to switch. Circuit ( 1 ) according to one of the preceding claims, which in the first strand ( 10.1 ) in series with the resistance circuit ( 110 ) has a Dimmungsschalter. Lighting system with LEDs ( 10 . 12 ), characterized in that the lighting system is the circuit ( 100 ) according to one of the preceding claims, wherein the first LED row ( 10 ) with the first LED ( 11 ) at the first connection points ( 1.1 . 1.2 ) and the second LED row ( 20 ) with the second LED ( 21 ) at the second connection points ( 2.1 . 2.2 ) connected. Method for controlling LEDs ( 11 . 21 ), with a first LED ( 11 ) and a second LED ( 21 ) by means of a parallel connection comprising a first and second strand ( 10.1 . 20.1 ), are connected in parallel and energized, characterized in that a LED series resistor, by a resistor circuit ( 110 ) with a first switch ( 115 ) and a first resistor ( 111 ) in the first strand ( 10.1 ) is switched between at least two values, which is a current flow through the resistor circuit ( 110 ) enable. Method according to claim 9, wherein by means of a control unit ( 200 ) a current through the first strand ( 10.1 ) and the first switch ( 115 ) is switched as a function of the measured current.

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