DE102008030365A1 - Individual light sources i.e. LEDs, controlling device for lighting device in motor vehicle i.e. aircraft, has current regulation unit that is assigned to parallel circuits, where individual light sources are arranged in parallel circuits - Google Patents

Abstract

The device (1) has a common power supply unit (10) with a voltage regulation unit and a control and/or regulation unit (9) for individual light sources (L1-Ln), where the individual light sources are arranged in parallel circuits (3.1-3.n) and a current regulation unit (8) is assigned to the parallel circuits. The current regulation unit has current-sources and/or current sinks (S1-Sn) which are assigned to decrease the parallel circuits. The current-sources and/or the current sinks are summarized in a current source module and/or a current-sink module (11).

Description

The The invention relates to a device for controlling in one Array arranged individual light sources, eg. B. LEDs, with a common Power supply unit with voltage regulation, and with control / regulation means for the individual light sources.

Individual light sources, LED's, in particular, are often controlled by a matrix provided, wherein the individual light sources, depending on their control in the matrix, a specific lighting scenario of the total formed Lighting device revealed. It is then possible, for example, in the case of lighting devices for motor vehicles the emission direction of the entire lighting device without to change the provision of moving parts by the Individual light sources are driven accordingly, in order to - to obtain a dipped beam - only part of the Illuminate solid angle. That way it would be possible to keep a motor vehicle headlight permanently in high beam operation, wherein - if Appropriate vehicles - the corresponding solid angle can remain unlit when the individual light sources accordingly be controlled or turned off.

One Problem arises here that when high-performance light-emitting diodes be used for such lighting, a matrix drive - such as For example, for advertising purposes or for marquee displays regularly used - not more is possible. Such a matrix drive requires namely a ratio of pulse current to continuous current from about 20: 1, d. H. with regard to pulsed switching the individual light sources in the matrix control is the respective Pulse current approx. 20 times higher than the corresponding continuous current provided. High-performance LEDs, such as those used in automotive lighting are required, but allow a maximum of a ratio from pulse current to continuous current of 1.5: 1, d. H. the pulse current must be maximum have an amplitude that is 1.5 times the amplitude of the continuous current is. Conversely, this means that in time-division multiplexing a matrix drive in the case of such high power LEDs a reduction of the light output would be the result overall.

From the DE 101 60 169 A1 is a lighting device for the interior of vehicles, in particular of aircraft cabins, known, wherein light emitting diodes are connected in series, and wherein each light emitting diode, a bypass switch is connected in parallel. The series connection of the LED's is connected to a power supply unit which, depending on how many LED's bridged by the bypass switch, that is deactivated, the output voltage automatically adjusted so that this voltage is at least equal to the sum of the forward voltages of the non-bridged LEDs, so to ensure their operation. This known lighting device has, inter alia, the disadvantage that the output voltage of the power supply unit fluctuates practically unpredictably, which makes the operation of the LED unsafe; Furthermore, the light emitting diodes can be overloaded by current peaks in the switching time, and finally, the control of the bypass switch, which may be formed for example by switching transistors or else by solenoids, only very expensive solvable.

It Now is an object of the invention to provide a device of the initially mentioned To propose a kind, which in a simple and inexpensive construction, which manages with comparatively few components, an efficient one Controlling the individual light sources allows, in particular also for each individual light source an optimal supply voltage or an optimal current should be achieved. Furthermore, should also monitor the individual light sources each for themselves can be, and any manufacturing tolerances be compensated cash. Another concern is the desired, predetermined brightness of the individual light sources even with temperature fluctuations sure.

The The invention accordingly provides a device such as defined in claim 1 before. Advantageous embodiments and further developments are in the dependent claims specified.

at the present device, the individual light source parallel circuits, each preferably only a single light source, in particular a single Light emitting diode (LED), included, but possibly also several individual light sources can be controlled separately, for each parallel circuit is provided its own current control. A Such training is inexpensive, with comparatively few components and with a low load for usually used computer means (CPU) gets by. By the current regulation Furthermore, a particularly favorable selection of high-performance LEDs is possible, and the current regulation has the further advantage that extraordinary small losses have to be accepted, whereas for example, with a voltage control for the LEDs a power loss is caused by series resistors. As a result, a particularly high number of individual light sources, In particular, LEDs are provided, for. An array of (more as) 100 LEDs, without any wiring of the LEDs in chains would be necessary.

In itself, it would be conceivable, each several Couple parallel circuits and connect to common power control means, but preferably each parallel circuit, which preferably contains only a single LED or single light source, as mentioned, associated with a separate power control means. The current control means may in particular contain current sources or current sinks which are assigned to the individual parallel circuits. These current sources or current sinks can preferably further be combined in a current source or sink module, which is accordingly connected via power lines to the individual parallel circuits or preferably individually connected in parallel LEDs. The current sources or current sinks can then be controlled and regulated in a corresponding manner centrally and / or decentrally in order to achieve the desired currents through the individual light sources and thus the desired brightness values or off / on states. Such a power source sink module could itself be formed by a known driver chip, such as the driver chip marketed under the designation TLC5940 by Texas Instruments; but it can also be implemented by its own ASIC block.

If the currents through the individual light sources or LEDs not should be high enough to achieve high light output is It is also possible to use the current range by means of current mirroring to increase.

It has also proven to be beneficial to the control and regulatory tasks to divide, and in this connection, the control means also a shared with the individual power control means common Controller unit, for example in the form of a microcontroller, contain. With the help of this controller unit can also the output voltage the voltage regulation, namely in particular one of the power supply unit associated voltage regulator or voltage converter (DC / DC converter), be influenced, so as the output voltage of the voltage converter to optimize. It is conceivable here, moreover, several provide such voltage transformers so as to be given by the given Redundancy a higher safety in operation or a higher To achieve fault tolerance. Anyway, with the voltage converter when using the present equipment in motor vehicles, to drive vehicle lights, converting the battery DC voltage (eg 16 volts) to a voltage of e.g. B. about 4.5 to 5 volts become.

The Voltage regulation can be further affected by disturbances and peak current loads the power supply unit to avoid multi-phase, preferably with phase offset, be executed, and in particular here also the so-called "spread spectrum" technology (frequency spreading) be used, in which a "jitter" of the pulse edges he follows.

at the current device may be the power sources or Lowering itself by their activation or deactivation as switching means but it is also for the individual light sources conceivable, for each parallel circuit a separate switching element provide, in particular, when a current mirroring for the purpose Increase of the operating current is provided. Such a thing Switching element may be a per se known, any switching element, like an electromechanical or mechanical switch, preferred however, becomes an electronic switching element, such as in particular a bipolar transistor or a field effect transistor. It can also be the current through the switching element to control the current be managed. To monitor the temperature of the switching element can a temperature sensor may be provided so as to apply the switching element protect. This temperature sensor is connected to the control / regulation means connected to at an overtemperature of the switching element reducing the current through the switching element or turning it off of the switching element bring about. In a similar way may also be current monitoring means associated with the control means for monitoring the current through the switching element (and be provided by the LED or individual light source), whereby a Protection of the switching element or the LED against overcurrent is possible. Furthermore, with the control / regulating means connected temperature sensors for monitoring the temperature from one or more individual light sources, and / or for monitoring the Ambient temperature and / or for monitoring the temperature be provided of the power source or sink module.

there can then depending on the temperature and depending on the current flow and the brightness be readjusted to the respective individual light source. In a similar way brightness differences between different LEDs, due to manufacturing tolerances, compensated by appropriate control / regulation become.

Pulse width modulation (PWM) means may preferably be provided for setting the brightness, wherein such PWM means may each be assigned to a single light source or else in each case to a plurality of individual light sources together for brightness control. The control / regulating means may further specify drive values for the PWM means in order to bring about certain lighting scenarios, for example in the case of a luminaire of a motor vehicle with a control via a bus interface through a CAN bus or LIN bus, with individual light sources being blanked out or else their brightness can be withdrawn nen or, so as to achieve, for example, a dimming effect in the oncoming vehicle, a cornering light, leveling, spotlighting or the like. Light shaping.

The PWM means are preferably arranged, the individual light sources to drive out of phase, with the control further also can be provided with a jitter; This can be more balanced Stresses of the power supply unit are achieved, and it disturbing effects can be minimized.

A further correction option results in an advantageous Then, when the control means are established by the regulation of the current through one or more of the individual light sources provided LEDs perform a color correction. This advantageous embodiment is based on that it a dependence of the color place of the exact color one respective LED from the current flowing through the LED, whereby here also the (barrier layer) temperature of the LED must be considered is. In the present device, the said Farbortkorrektur insofar in a particularly advantageous manner, as a Current control is provided for the individual light sources.

The Invention will be described below with reference to preferred embodiments, to which, however, it should not be limited, and under Reference to the drawings further explained. It demonstrate:

1 a block diagram of a first embodiment of the device according to the invention;

2 similar in a block diagram 1 a modified embodiment of the device according to the invention, with decentralized diagnosis and PWM function;

3 a further embodiment of the device according to the invention in a block diagram similar 1 and 2 However, now provided a current mirror means with a view to achieving a higher LED current;

4 in a block diagram similar to a device with multiple LED circuits 3 as well as with a common current sink module; and

5 a diagram an example of a pulse width modulation for z. B. three LED's with phase shift in order to obtain a uniform possible load on the power supply unit and a robustness to interference.

In 1 is a facility 1 for controlling an array 2 illustrated as single light sources LED's L1, L2 ... Ln illustrates, each in its own circle, a parallel circuit 3.1 . 3.2 ... 3.n , are arranged. In the exemplary embodiment shown, each of these contains parallel circuits 3.i , with i = 1, 2 ... n, one LED Li, but it would also be conceivable per parallel circuit 3.i several, z. B. two or more, LED's provide.

At each LED Li is used as a diagnostic agent 4 an operational amplifier (or comparator) 5 turned on, with a diagnostic bus 6 connected, this diagnostic bus 6 with a central controller unit 7 , preferably in the form of a microcontroller. This controller unit 7 forms together with exemplary illustrated in a common unit current control means 8th , the current sources S1, S2 ... Sn are assigned as drive means, control means 9 for the LED Li. The controller unit 7 controls a DC-DC converter (DC / DC converter) 10 on, which provides the supply voltage V + for the LED's Li together with current sources Si and thus forms at least a part of an otherwise not further illustrated power supply unit. Optionally, two or more such voltage converter 10 be provided so as to ensure a higher reliability due to the redundancy.

The current sources Si are in a common power source module 11 summarized, in which also the aforementioned current control means 8th are integrated.

In operation, with the help of the control / regulating means 9 Overall, the desired setting of the LED's Li given the current supplied by the current sources Si, on the one hand, via the central controller unit 7 , corresponding values are given and via the current control means 8th and the current sources Si, the respective currents are set or adjusted to the desired value. It is possible to compensate for differences in brightness due to manufacturing tolerances of the LED's Li, as well as divergent power flows, for example, due to different operating temperatures. To monitor the temperature of the LED's Li is according to 1 a temperature sensor 12 in the area of the LED's Li (or of switching means, s. 4 ), the output of which, for example, to the controller unit 7 is laid. It would also be conceivable, however, this temperature sensor 12 with the current control means 8th connect to. Another temperature sensor 13 is the power source module 11 assigned to monitor its temperature and optionally, if a predetermined maximum temperature is exceeded, to be able to restore the current or a shutdown can. Another temperature sensor 14 is used to monitor the Ambient temperature, and the output signal of this temperature sensor 14 for the ambient temperature, the controller unit is preferred 7 fed or it can be read directly or indirectly in the bus.

With the help of diagnostic means 4 the current and voltage at the individual LEDs Li are detected and corresponding actual value signals above the diagnostic bus 6 to the controller unit 7 transmitted to about this a possible readjustment of the individual currents to the LED's Li to cause.

The cathodes of the LED's Li are as out 1 can be seen, connected to ground, which in an advantageous manner - when mounted on a ground potential having carrier, for. B. heatsink or PCB - can be used for cooling.

In the embodiment according to 1 can the controller unit 7 optionally provide a pulse width modulation (PWM) for the LED's Li in their power supply. Such a pulse width modulation is according to the embodiment 2 into the current control means 8th integrated, as with a PWM module 15 schematically in 2 is illustrated. Furthermore, in this current control means 8th also a diagnostic module 16 integrated with the diagnostic bus 6 is connected, wherein in the embodiment according to 2 the diagnostic means 4 (or operational amplifier 5 ) instead of the LED's Li, as in 1 , Now are connected to the power sources Si. In this way, the current can be detected by the individual LED's Li and used for diagnostic purposes - in this case, within the diagnostic module 16 the current control means 8th into the power source module 11 integrated. This allows the controller unit 7 additionally relieved and subsequently increasingly used for central control tasks.

Furthermore, it is off 2 again a DC-DC converter 10 apparent from the controller unit 7 in the same way as according to 1 is driven so that the DC-DC converter 10 a regulated DC voltage V + outputs.

Although in 2 not shown, can also be at the device 1 according to 2 again temperature sensors like the temperature sensors 12 . 13 and 14 according to 1 be provided in order to provide a temperature-dependent current control can.

In 3 is an embodiment of the device according to the invention 1 shown, in turn, components, the components according to 1 or 2 correspond, are provided with the same reference numerals; the embodiment according to 3 is now so far from that of 1 modified, as in the parallel circles, z. B. in the parallel circle 3.n , which is exemplary for all parallel circles in 3 Shown is current mirror means 17 are included in order to achieve by current mirroring an expansion of the current range (by multiplication), if the current sources do not have enough current carrying capacity. Specifically, the current mirror means 17 an operational amplifier 18 of which an input, for example the "-" input, is connected to the associated current source, eg Sn, the connection point being via a resistor 19 is applied to the supply voltage V +. The other input, for example the "+" input, of the operational amplifier 18 is above a resistance 20 at the supply voltage V +, wherein with the connection point further the collector of a usable as a switching means bipolar transistor 21 whose base is connected to the output of the operational amplifier 18 connected is. The emitter of the transistor 21 is then with the LED, z. B. Ln connected. Of course, other switching means implementations are conceivable, such as in particular with a field effect transistor or other electronic switching means.

The ratio of the values of the resistors 19 and 20 results in the embodiment shown, the multiplication factor for the current range extension.

In 4 is such a device 1 illustrated in a more complete illustration, wherein the power source module 11 - here better current sink module, in view of the selected connection potentials and current characteristics - similar to the representation in 3 with the controller unit 7 via a data bus 22 connected is. Each current sink S1, Si, Sn is associated with current mirroring means 17 for the associated LED Ln connected as above with reference to 3 was explained. In 4 is further illustrated that these current mirror means 17 along with the resistors 19 . 20 , the transistor provided as switching means 21 and in particular the LED Li or Ln together with the switched on operational amplifier or comparator 5 (as a diagnostic agent 4 ) to a separate module 23 are summarized, which is the parallel circle 3.n (or in general 3.i , with i = 1, 2 ... n). These modules 23 or parallel circles 3.i are parallel to the current sink module (or power source module) 11 turned on, and so are their diagnostic tools 4 parallel to the diagnostic bus 6 turned on. This diagnostic bus 6 can also be used to control the DC / DC converter 10 For example, with a PWM module (not shown) may be provided.

With the in 2 shown or an equivalent PWM module 15 can in a conventional manner the power and thus the brightness of the LED's Li can be adjusted. It is conceivable, the individual parallel circles 3.i or LED's Li individually and in phase shifted to control. In particular, it can be provided to dim the LEDs Li all individually, each by itself.

5 shows in a diagram very schematically and exemplarily three pulse trains PWM 1, PWM 2 and PWM 3, which are, for example, switching signals for the current sources Si, the different LED's Li are assigned, the phase shift between the three pulse signals PWM 1, PWM 2 and PWM 3 off 3 It is also recognizable as the fact that the pulses have different widths for setting a corresponding brightness of the LEDs. For example, if the second LED has a higher light output, to compensate for this, to produce the same brightness as the other LED's, narrower switching pulses, for shorter turn-on times, may be provided in the PWM 2 pulse signal.

Although the invention has been explained above with reference to preferred embodiments, further modifications and modifications are possible within the scope of the invention. Thus, it is particularly conceivable to control the switching means in the current path to the LEDs L1 ... Ln directly by a central microcontroller or microcomputer. This variant is especially easy to implement when in the LED array 2 a rather small number of LEDs is included, so that not too high computer power for each desired control and brightness control is required. The more LED's are available, the more it is recommended, however, a part of the control function in separate components 8th to relocate, so the microcontroller 7 to relieve.

With appropriate proximity of the circuit units 3 and the microcontroller 9 to the LEDs L1 ... Ln it can be enough, instead of the three temperature sensors 12 . 13 and 14 only one temperature sensor, such as the temperature sensor 12 to provide. On the other hand, however, in each case a plurality of temperature sensors can be provided, in particular in each case a plurality of temperature sensors 14 for detecting the ambient temperature and several temperature sensors 12 in the field of LEDs. For simple applications, where the uniformity of the brightness of the LEDs or generally the individual light sources are not set too high demands, the current measurement by means of the diagnostic means 4 omitted, although then a lower security, namely in the case of overcurrents, is given.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 10160169 A1 [0004]

Claims (21)

Facility ( 1 ) for controlling in an array ( 2 ) arranged individual light sources, for. B. LED's (Li), with a common power supply unit ( 10 ) with voltage regulation and with control means ( 9 ) for the individual light sources, characterized in that the individual light sources (Li) in parallel circuits ( 3.i ) are arranged and the parallel circuits ( 3.i ) Current control means ( 8th ) assigned. Device according to claim 1, characterized in that in each case a current control means ( 3.i ) is associated with a parallel circuit (Li). Device according to claim 1 or 2, characterized in that the current control means (Li) the parallel circuits ( 3.i ) associated power sources or sinks (Si) included. Device according to claim 3, characterized in that the current sources or sinks (Si) in a current source or sink module ( 11 ) are summarized. Device according to claim 3 or 4, characterized in that the current control means ( 8th ) Current mirror means ( 17 ) contain. Device according to one of Claims 1 to 5, characterized in that the control means ( 9 ) a the individual current control means ( 8th ) associated common controller unit ( 7 ) contain. Device according to claim 6, characterized in that the controller unit ( 7 ) also the output voltage of a power supply unit associated voltage converter ( 10 ). Device according to one of claims 1 to 7, characterized in that the voltage regulation with "spread spectrum" Technology is executed. Device according to one of claims 1 to 8, characterized in that the voltage regulation a multi-phase Switching regulator, preferably with phase offset having. Device according to one of claims 1 to 9, characterized in that in series with each parallel circuit ( 3.i ) a switching element ( 21 ) is arranged. Device according to claim 10, characterized in that the switching element ( 21 ) is an electronic switching element. Device according to claim 10 or 11, characterized in that the current through the switching element ( 21 ) is regulated. Device according to one of claims 10 to 12, characterized by a control means ( 9 ) connected temperature sensor ( 12 ) for monitoring the temperature of the switching element. Device according to one of claims 10 to 13, characterized by the control / regulating means ( 9 ) connected electricity monitoring means ( 4 ) for monitoring the current through the switching element. Device according to one of claims 1 to 14, characterized by a control means ( 9 ) connected temperature sensor ( 12 ) for monitoring the temperature of one or more individual light sources. Device according to one of claims 1 to 15, characterized by a control means ( 9 ) connect the temperature sensor ( 14 ) for monitoring the ambient temperature. Device according to one of claims 5 to 16, characterized by a control means ( 9 ) connected temperature sensor ( 13 ) for monitoring the temperature of the power source and sink module. Device according to one of claims 1 to 17, characterized in that pulse width modulation (PWM) means ( 15 ) are provided for single light source brightness control. Device according to claim 18, characterized in that the control means ( 9 ) Specify control values for the PWM funds in order to generate specific light scenarios. Device according to claim 18 or 19, characterized in that the PWM means ( 15 ) are arranged to control the individual light sources (Li) phase-shifted. Device according to one of Claims 1 to 20, characterized in that the control means ( 9 ) are arranged to perform a color correction by the regulation of the current flowing through one or more of the LED provided as individual light sources (Li).