EP3453227A1

EP3453227A1 - Illumination device

Info

Publication number: EP3453227A1
Application number: EP17718945.3A
Authority: EP
Inventors: Robert Isele; Florian Altinger; Juergen Bruegl
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2016-05-04
Filing date: 2017-04-25
Publication date: 2019-03-13
Anticipated expiration: 2037-04-25
Also published as: EP3453227B1; WO2017190981A1; DE102016207729A1

Abstract

The invention relates to an illumination device, in particular for a motor vehicle, comprising one or more multi-color LED units (3) which each have a settable brightness and a settable color point. Each multi-color LED unit (3) is an individual semiconductor component having multiple single-color LEDs (301, 302, 303, 304) of different colors and a microcontroller (4), wherein the single-color LEDs (301, 302, 303, 304) and the microcontroller (4) are surrounded by a housing of the semiconductor component. The microcontroller (4) is designed to determine a current temperature value of an associated multi-color LED unit (3) on the basis of at least one portion of the operating voltages and/or operating currents of the single-color LEDs (301, 302, 303, 304) of the associated multi-color LED unit (3) and to control the associated multi-color LED unit (3) depending on the current temperature value.

Description

lighting device

The invention relates to a lighting device, in particular for a motor vehicle.

From the prior art it is known to use multi-color LED units for lighting devices in motor vehicles. These LED units comprise a plurality of single color LEDs and are typically driven by LED drivers to vary the brightness and color location (i.e., the mixed color). For this purpose, a module is used with a microprocessor, on the one hand takes over communication with a motor vehicle data bus and on the other drives the LED units, usually via PWM outputs. As a motor vehicle data bus is often the so-called. LIN bus (LIN = Local Interconnect Network) is used.

Also known in the art are novel multi-color LED units having an integrated circuit. In these LED units, the single-color LEDs and the integrated circuit are housed in a common housing, whereby a high packing density can be achieved. The individual LED units are controlled by a data stream.

To date, parametrizations required in multi-color LED lighting fixtures to operate the individual LED units are stored in a central processing module. This has the disadvantage that locally different operating conditions of the individual LED units are only insufficiently compensated, which can lead to a non-uniform appearance of the lighting device.

The document WO 2014/067830 A1 discloses a method and an arrangement for the temperature-corrected control of LEDs by means of look-up tables. In this case, in an LED module comprising a plurality of LED channels for each target color location, which can be reached by the LED module, a look-up table is provided in which the operating current for each LED channel is stored as a function of the temperature. The current temperature is measured via a thermistor outside the LED module. Document US 2015/0002023 A1 discloses an LED device with a plurality of LEDs. The temperature of the LED device is determined by the operating voltage of one of the LEDs.

The object of the invention is to provide a compact lighting device of at least one multi-color LED unit with an improved temperature-dependent operation control.

This object is achieved by the lighting device according to claim 1. Further developments of the invention are defined in the dependent claims.

The lighting device according to the invention is preferably provided for a motor vehicle, such as e.g. a car and possibly also a truck. The lighting device comprises one or more multi-color LED units, each with adjustable color location and adjustable brightness (i.e., light intensity). The term color locus is well known to those skilled in the art and describes the blend color produced by the respective multi-color LED unit. The color locus may be indicated, for example, as a location in a color diagram, in particular in a color diagram of the CIE standard valency system.

In the lighting device according to the invention, each multi-color LED unit is a single semiconductor device having a plurality of and preferably at least three single-color LEDs of different colors. The single semiconductor device further comprises a microcontroller. The single-color LEDs and the microcontroller are surrounded by a housing of the semiconductor component, ie they are accommodated in a common housing of the semiconductor component. In the lighting device according to the invention, the microcontroller is configured to determine a current (ie presently) temperature value of a respective multi-color LED unit based on at least a portion of the operating voltages and / or operating currents of the single-color LEDs of the respective multi-color LED unit, and to control the respective multi-color LED unit as a function of this current temperature value. The current temperature value is the current temperature value. The lighting device according to the invention has the advantage that can be dispensed with a temperature measurement by means of a separate temperature sensor, whereby the space for the lighting device is reduced and further costs are saved. Instead of a direct temperature measurement, operating voltages or operating currents of the individual single-color LEDs of a respective multi-color LED unit are used. Here, one makes use of the fact that these operating voltages or operating currents depend on the temperature, so that the temperature can be determined indirectly via this. Moreover, it is advantageous in the lighting device according to the invention that the temperature-dependent control of the multi-color LED unit is integrated in a microcontroller which is part of a single semiconductor component of the multi-color LED unit. As a result, the temperature-dependent control can be carried out individually for the individual multi-color LED units via an integrated logic in the semiconductor component of the LED unit.

In a particularly preferred embodiment, the microcontroller of a respective multi-color LED unit is adapted to control each single-color LED of the respective multi-color LED unit in such a function of the current temperature value of the respective multi-color LED unit that a set color location and a set brightness during operation of the respective multi-color LED unit are kept constant. As a result, a desired brightness or a desired color location can be set individually and with high precision, taking into account local temperatures of the individual multicolor LED units, whereby a uniform appearance of the lighting device is achieved.

In a preferred variant, the microcontroller of at least part of the multicolor LED unit is set up to control each single color LED based on the control of the operating current of the respective single color LED, for example via pulse width modulation.

Depending on the design of the lighting device according to the invention, the temperature value can be determined in different ways based on the operating voltages or operating currents. However, the determination of the current temperature value preferably takes place based on tables or characteristic curves. In contrast to a table, a characteristic curve describes a continuous relationship between several other variables. To realize such an embodiment, characteristic curves or tables are stored in the microcontroller of at least one part of the multicolor LED units for a respective single-color LED of at least one part of the single-color LEDs of the respective multicolor LED unit Table is specific to an operating current of the respective single color LED. In other words, there are several characteristics for different adjustable operating currents. The respective characteristic curve or table specifies a temperature as a function of the operating voltage of the respective single-color LED. The microcontroller is configured to read from the characteristic curve or table for the current operating current, which is set in the respective single-color LED, the temperature for the current operating voltage, which can be measured with a suitable sensor, and based on the read out or read Temperatures to determine the current temperature value. If temperature values of several or all single-color LEDs of the corresponding multicolor LED unit are determined, the mean value from these read-out temperatures can be used, for example, as the current temperature value.

In a further preferred variant of the illumination device according to the invention, the microcontroller of at least a part of the multicolor LED units is configured such that it, in the event that the current temperature value exceeds a predetermined threshold, the brightness of the respective multi-color LED unit (ie the multi-color LED unit to which the microcontroller belongs). This will ensure that the multi-color LED unit is damaged due to excessive temperatures. In this case, a relationship can preferably be predetermined according to which the brightness of the multicolor LED unit is reduced the more, the more the predetermined threshold is exceeded. Optionally, the brightness of the multi-color LED unit may also be reduced to zero, i. the corresponding multi-color LED unit will be turned off. This can be achieved for example by a second threshold, which is higher than the predetermined threshold. If the current temperature exceeds this second threshold, the multi-color LED unit is turned off.

In a particularly preferred embodiment, the lighting device according to the invention comprises a plurality of multi-color LED units which are connected to an internal data bus (ie a data bus within the lighting device). This internal data bus is in turn coupled to a processing module, the Processing module is set to give internal control commands for adjusting the brightness and the color location of each multi-color LED units on the internal data bus. Preferably, the above processing module is arranged to receive external control commands from a motor vehicle data bus and to convert them to the above internal control commands.

In the embodiment just described, a simple control of the individual multi-color LED units is achieved via an internal data bus. The internal data bus may e.g. an SPI (Serial Protocol Interface) data bus, or optionally another data bus, such as a data bus. a differential data bus that encodes digital data about a voltage difference between two lines. The above motor vehicle data bus may, for example, be a LIN bus (LIN = Local Interconnect Network) or else a CAN bus (CAN = Controller Area Network).

In a further preferred embodiment, at least a part of the multicolor LED units comprises one or more RGB LED units and / or RGBW LED units. An RGB LED unit comprises, in a manner known per se, a red, green and blue single-color LED, and an RGBW LED unit also comprises a white-light LED in addition to a red, green and blue LED.

In a particularly preferred embodiment, the lighting device is an interior lighting in a motor vehicle or possibly also a Au ßenbeleuchtung on the Au ßenseite the motor vehicle. As a result, attractive lighting effects can be generated with a homogeneous appearance.

In addition to the lighting device described above, the invention relates to a motor vehicle, in particular a car or possibly also a truck, which comprises one or more of the lighting devices according to the invention or of preferred variants of these lighting devices.

An embodiment of the invention will be described below in detail with reference to the accompanying drawings.

Show it: 1 shows a schematic representation of an embodiment of a lighting device according to the invention; and

2 shows a detailed view of an LED unit from FIG. 1.

In the following, an embodiment of the invention will be described with reference to a lighting device, which is installed in a motor vehicle as interior lighting and as a light source comprises a plurality of arranged on a tape multi-color LED units 3. These multi-color LED units, which are also referred to below simply as LED units, each represent a single semiconductor device having a plurality of single color LEDs 301 to 304 and a microcontroller 4. The single color LEDs and the microcontroller are in a common housing of the Integrated semiconductor device. The single color LED 301 is a red LED, the single color LED 302 is a green LED, the single color LED 303 is a blue LED, and the single color LED 304 is a white LED. With the ribbon-shaped LED units, a very high packing density can be achieved (depending on the housing form from 144 to 367 LEDs / m).

The individual LED units 3 are driven by a digital data stream in the form of a bit stream supplied to the individual LED units by means of an internal data bus 2 (i.e., a data bus provided internally in the lighting device). The internal data bus comprises a line CL for the clock and a line DL for the bit stream.

The signals on the internal data bus 2 come from a processing module 1, which is coupled to a LIN bus 6 of the motor vehicle. The processing module comprises a LIN transceiver 101, which picks up corresponding digital signals for driving the LED units 3 from the LIN bus 6, and a microprocessor 102, which converts the tapped signals into corresponding data signals on the data line DL. The signals transmitted on the LIN bus 6 in this case comprise signals which are intended for the lighting device and define a light pattern to be set for the lighting device. These signals in turn come from a control unit of the motor vehicle, which determines the light pattern to be generated based on an input of the driver, for example, and outputs it as a corresponding signal to the LIN bus. about the processing module 1 is detected whether the light pattern is provided according to the current signal on the LIN bus 6 for the lighting device. If this is the case, this signal is converted by means of the microprocessor 102 into a corresponding signal for the internal data bus 2.

The internal data bus 2 may e.g. be an SPI bus. Preferably, the signals for the SPI bus are generated by the microprocessor 102 by means of software SPI. Software SPI is well known in the art and is a program library that allows any free pins of microprocessor 102 to be used to deliver signals to the SPI bus. Alternatively, however, hardware SPI can also be used. Special SPI pins are provided for signal output to the SPI bus. The use of software SPI has the advantage that in the internal data bus 2 a plurality of lines DL and CL can be provided for driving a larger number of LED units 3. As an alternative to an SPI bus, the internal data bus can also be designed as a differential data bus or as any other data bus. A differential data bus is characterized in that it encodes digital data via a voltage difference between two lines.

In the embodiment of FIG. 1, two power lines L1 and L2 are provided in addition to the lines CL and DL, which are connected to a DC power supply 5. Based on the bit stream received via the data line DL, a PWM modulation of the current supplied to the individual LEDs 301 to 304 is effected in order thereby to drive the LEDs in accordance with the bit stream on the data line DL.

The structure of a single LED unit 3 of FIG. 1 is shown in detail in FIG. All illustrated components of the LED unit are integrated in a single semiconductor device. The signals of the data bus 2 are received via a communication interface COM of the LED unit 3. The clock signal of the clock line CL is forwarded to the microprocessor 401 described below, whereas the data stream of the data line DL is given after decoding in the communication interface COM on 8-bit shift registers SRO, SR1, SR2, SR3 and SR4. The value output by the shift register SRO indicates the desired overall brightness of the LED unit, whereas the values of the shift registers SR1 to SR4 indicate the color components of the individual single color LEDs for generating the desired mixed color. ben. In particular, the color component of the red LED 301 is output via the shift register SR1, the color component of the green LED 302 via the shift register SR2, the color component of the blue LED 303 via the shift register 303, and the color component of the white LED 304 via the shift register 304.

The values of the individual shift registers are supplied to the microcontroller 4, which consists of a logic or a microprocessor 401 and an associated nonvolatile EEPROM memory 402. In this memory, inter alia, calibration data are stored, which come from a calibration process of the LED unit and set for a given standard temperature value of the LED unit, how to set the operating currents of each single color LEDs, so that derive from the shift register SRO total brightness value and the color mixing (ie, the related color location) can be achieved according to the values from the shift registers SR1 to SR4.

The microprocessor 401 accesses the values stored in the memory 402 and also determines a current temperature value of the LED unit 3. The determination of this current temperature value in the embodiment described here is based on characteristics which are related to respective set operating currents of the individual single-color LEDs indicate between the operating voltage of the respective single color LED and the temperatures. The operating voltage can be measured by a suitable voltage sensor in the LED unit. The current temperature of the LED unit is obtained e.g. by averaging the temperatures of all single-color LEDs. The above type of temperature determination is familiar to the person skilled in the art and is described, for example, in document US 2015/0002023 A1. For the first time, such a temperature determination is combined with an algorithm for temperature compensation, which is integrated directly in the LED unit or its microprocessor, as will be explained in more detail below.

A temperature algorithm is stored in the microprocessor 401, which adjusts the corresponding operating currents for the abovementioned standard temperature value, accessing the memory 402, and appropriately corrects these operating currents if the current temperature value deviates from the standard temperature value. The correction is designed in such a way that the desired brightness and the desired color location correspond to one another. The values from the shift registers can also be set correctly in the case of temperature fluctuations.

The temperature algorithm of the microprocessor 401 thus takes into account the fact that the temperature of the LED unit 3 has effects on its operation, so that a temperature-dependent correction must be carried out in order to achieve a desired brightness and a desired color location. Corresponding algorithms for temperature compensation are known per se from the prior art. According to the invention, such an algorithm is now stored in a microcontroller, which is part of the semiconductor component of an LED unit. In this way, the operation of the individual multi-color LED units in a lighting device can be adjusted individually and very precisely to the current temperature.

The operating currents for the individual LEDs 301 to 304 are provided via a voltage regulator RE, which receives the positive voltage VDD and the negative voltage VSS from the voltage supply 5 shown in FIG. The microprocessor 401 also generates a clock for a corresponding oscillator OS, which is supplied to PWM generators G1, G2, G3 and G4. The operating currents of the individual LEDs 301 to 304 are generated in the generators G1 to G4 via pulse width modulation. The values of the operating currents originating from the algorithm for temperature compensation are given by the microprocessor 401 to the individual generators G1 to G4. The generator G1 generates the current for the red LED 301 by means of pulse width modulation, the generator G2 the current for the green LED 302, the generator G3 the current for the blue LED 303 and the generator G4 the current for the white LED 304. About the of PWM signals generated by the individual generators, which reach the single-color LEDs via the current output CO, the corresponding light with the desired brightness and the desired color location is then set for LED unit 3 in accordance with the signal which is supplied via the internal data bus 2 the LED unit arrives.

The embodiments of the invention described above have a number of advantages. In particular, a temperature-corrected control based on a temperature value is made possible, which is determined indirectly via operating currents or operating voltages of the single-color LED units of a multi-color LED module. Consequently, it is possible to dispense with the use of a separate temperature sensor be reduced, whereby the space is reduced and costs are saved. Moreover, the temperature compensation algorithm is integrated in a single semiconductor device of a respective multi-color LED unit. Thus, integrated logic in a multi-color LED module is used to implement temperature compensation over this. As a result, the desired brightness and the desired color location can be set individually and with high precision for each LED unit as a function of the temperature at the installation location of the respective LED unit. In this way, a uniform appearance of the LED unit or a LED tape from many LED units can be guaranteed over the entire lifetime.

LIST OF REFERENCE NUMBERS

1 processing module

101 LIN transceivers

102 microprocessor

2 internal data bus

3 multi-color LED units

301, 302, 303, 304 single color LEDs

4 microcontrollers

401 microprocessor

402 EEPROM

5 power supply

6 motor vehicle data bus

CL line for clock signal

DL data line

L1, L2 power lines

COM communication interface

SRO, SR1, SR2, SR3, SR4 shift registers

G1, G2, G3, G4 PWM generators

OS oscillator

RE voltage regulator

VDD, VSS voltages

CO current output

Claims

claims

1 . Lighting device, in particular for a motor vehicle, comprising one or more multi-color LED units (3), each with adjustable brightness and adjustable color location, each multi-color LED unit (3) comprising a single semiconductor component with a plurality of single-color LEDs (301, 302, 303, 304) of different color and a microcontroller (4), the monochrome LEDs (301, 302, 303, 304) and the microcontroller (4) being surrounded by a housing of the semiconductor device, the microcontroller (4) being arranged for this purpose is, a current temperature value of a respective multi-color LED unit (3) based on at least a part of the operating voltages and / or operating currents of the single-color LEDs (301, 302, 303, 304) of the respective multi-color LED unit (3) determine and control the respective multi-color LED unit (3) depending on the current temperature value.

2. Lighting device according to claim 1, characterized in that the microcontroller (4) of a respective multi-color LED unit (3) is adapted to each single-color LED (301, 302, 303, 304) of the respective multi-color LED unit (3) in response to the current temperature value of the respective multi-color LED unit (3) to control that a set color location and a set brightness during operation of the respective multi-color LED unit (3) are kept constant.

3. Lighting device according to claim 1 or 2, characterized in that the microcontroller (4) of at least a part of the multi-color LED units (3) is adapted to each single-color LED (301, 302, 303, 304) based on the Control the operating current of the respective single color LED (301, 302, 303, 304) to control.

4. Lighting device according to one of the preceding claims, characterized in that in the microcontroller (4) at least a part of the multi-color LED units (3) for a respective single color LED (301, 302, 303, 304) at least a part of Single-color LEDs (301, 302, 303, 304) of the respective multi-color LED unit (3) characteristic curves or tables are deposited, with a respective Characteristic or table for an adjustable brightness and an adjustable color locus is specific and depending on the operating voltage or the operating current of the respective monochrome LED (301, 302, 303, 304) specifies a temperature, wherein the microcontroller (4) is adapted to off the characteristic or table for the set brightness and the set color location, the temperature for the current operating voltage or the current operating current of the respective single-color LED (301, 302, 303, 304) read and determine the current temperature value based on the read or the temperatures ,

5. Lighting device according to one of the preceding claims, characterized in that the microcontroller (4) at least a part of the multi-color LED units (3) is designed such that it, in the event that the current temperature exceeds a predetermined threshold, the brightness the multi-color LED unit (3) is reduced.

6. Lighting device according to one of the preceding claims, characterized in that the lighting device comprises a plurality of multi-color LED units (3) which are connected to an internal data bus (2) which is coupled to a processing module (1), wherein the processing module

(1) is adapted to provide internal control commands for adjusting the brightness and color location of each multi-color LED unit (3) on the internal data bus

(2) to give.

7. Lighting device according to claim 6, characterized in that the processing module (1) is adapted to receive external control commands from a motor vehicle data bus (6) and to convert it into the internal control commands.

8. Lighting device according to one of the preceding claims, characterized in that at least part of the multi-color LED units (4) comprises one or more RGB LED units and / or RGBW LED units.

9. Lighting device according to one of the preceding claims, characterized in that the lighting device interior lighting in a motor vehicle or Au ßenbeleuchtung on the Au ßenseite the motor vehicle.

10. Motor vehicle comprising one or more lighting devices according to one of the preceding claims.