EP3453228B1 - Illumination device - Google Patents

Description

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

It is known from the prior art to use multicolor LED units for lighting devices in motor vehicles. These LED units include several single-color LEDs and are usually controlled with LED drivers in order to vary the brightness and the color location (i.e. the mixed color). For this purpose, a module with a microprocessor is used, which on the one hand takes over communication with a motor vehicle data bus and on the other hand drives the LED units, usually via PWM outputs. The so-called LIN bus (LIN = Local Interconnect Network) is often used as the motor vehicle data bus.

Novel multi-color LED units which have an integrated circuit are also known from the prior art. With these LED units, the single-color LEDs and the integrated circuit are housed in a common housing, which enables a high packing density to be achieved. The individual LED units are controlled via a data stream.

To date, parameterizations that are required in lighting devices with multicolor LED units for operating the individual LED units have been 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 publication WO 2014/067830 A1 discloses a method and an arrangement for temperature-corrected control of LEDs using look-up tables. In this case, a look-up table is provided in an LED module consisting of several LED channels for each target color location that can be reached by the LED module, in which the operating current for each LED channel is stored as a function of temperature. The current temperature is measured via a thermistor outside the LED module.

The publication US 2010/0259198 A1 discloses a method for setting a color location in a lighting module as a function of a determined temperature. As part of this setting, calibration data is also used.

In the publication WO 2004/086822 A1 discloses a motor vehicle lamp module which comprises individual LEDs as lamps and sensors for detecting external and / or internal influences during the operation of the LEDs and / or production-related properties of the LEDs. The LEDs are controlled depending on the detected influences or properties via a microcontroller circuit.

The object of the invention is to provide a lighting device comprising a plurality of multi-color LED units with an improved temperature-dependent operating 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 a car and possibly also a truck. The lighting device comprises a plurality of multi-color LED units, each with an adjustable color locus and adjustable brightness (i.e. light intensity). The term color location is well known to the person skilled in the art and describes the mixed color which is generated by the respective multicolor LED unit. The color location can be specified, for example, as a location in a color diagram, in particular in a color diagram of the CIE standard valence system.

In the lighting device according to the invention, each multicolor LED unit is an individual semiconductor component with several and preferably at least three single-color LEDs of different colors. The individual semiconductor component also includes a microcontroller. The single-color LEDs and the microcontroller of each multi-color LED unit are surrounded by a corresponding housing of the semiconductor component, ie they are accommodated in a common housing of the semiconductor component. According to the invention, a temperature sensor is integrated in the semiconductor component of a respective multi-color LED unit, which has a current (ie currently present) temperature value measures the respective multicolor LED unit and makes it available to the microcontroller. The microcontroller is set up to control a respective multicolor LED unit as a function of the current temperature value of the respective multicolor LED unit.

The lighting device according to the invention has the advantage that by directly integrating a temperature sensor in the respective multicolor LED unit, its temperature can be recorded with high precision and thus a temperature-dependent operating control can be better adapted to the current environmental conditions of the respective multicolor LED unit. The temperature measurement of the temperature sensor can be based on technologies known per se. For example, the temperature sensor measure the temperature using a resistance measurement or infrared or a diode.

In a particularly preferred embodiment, the microcontroller of a respective multi-color LED unit is set up to control each single-color LED of the respective multi-color LED unit in dependence on the current temperature value of the respective multi-color LED unit in such a way that a set color location and a set brightness can be kept constant during operation of the respective multi-color LED unit. In this way, a desired brightness or a desired color location can be set individually and with high precision, taking into account local temperatures of the individual multi-color LED units, as a result of which the lighting device has a uniform appearance.

In a preferred variant, the microcontroller of at least some of the multi-color LED units 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.

In a further preferred variant of the lighting device according to the invention, the microcontroller of at least some of the multicolor LED units is designed such that, in the event that the current temperature value exceeds a predefined threshold, the brightness of the respective multicolor LED unit (ie the multicolor -LED unit to which the microcontroller belongs). This ensures 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. If necessary, the brightness of the multicolor LED unit can also be reduced to zero, i.e. the corresponding multi-color LED unit can be switched off. This can be achieved, for example, by a second threshold that is higher than the predetermined threshold. If the current temperature exceeds this second threshold, the multi-color LED unit is switched off.

In a particularly preferred embodiment, the lighting device according to the invention comprises a plurality of multicolor LED units which are connected to an internal data bus (ie a data bus within the lighting device) are connected. This internal data bus is in turn coupled to a processing module, the processing module being set up to issue internal control commands for setting the brightness and the color location of the individual multi-color LED units on the internal data bus. The above processing module is preferably set up to receive external control commands from a motor vehicle data bus and to convert them into the above internal control commands.

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

In a further preferred embodiment, at least some of the multicolor LED units comprise one or more RGB LED units and / or RGBW LED units. An RGB LED unit comprises a red, green and blue single-color LED in a manner known per se, 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 interior lighting in a motor vehicle or possibly also external lighting on the outside of the motor vehicle. In this way, attractive lighting effects with a homogeneous appearance can be generated.

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 is described in detail below with reference to the accompanying figures.

Fig. 1

eine schematische Darstellung einer Ausführungsform einer erfindungsgemäßen Beleuchtungsvorrichtung; und

Fig. 2

eine Detailansicht einer LED-Einheit aus Fig. 1.

Show it:

Fig. 1

a schematic representation of an embodiment of a lighting device according to the invention; and

Fig. 2

a detailed view of an LED unit Fig. 1 .

An embodiment of the invention is described below with the aid of a lighting device which is installed in a motor vehicle as interior lighting and which comprises a plurality of multicolor LED units 3 arranged on a band as the illuminant. These multi-color LED units, which are also referred to simply as LED units below, each represent a single semiconductor component with a plurality of single-color LEDs 301 to 304 and a microcontroller 4. The single-color LEDs and the microcontroller and the temperature sensor described below are integrated in a common housing of the semiconductor component. 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. A very high packing density can be achieved with the band-shaped LED units (depending on the housing shape from 144 to 367 LEDs / m).

The individual LED units 3 are controlled via a digital data stream in the form of a bit stream, which is fed 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 originate 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 taps the corresponding digital signals for controlling 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 include signals which are intended for the lighting device and a light pattern to be set for the lighting device establish. These signals in turn come from a control unit of the motor vehicle, which, for example, determines the light pattern to be generated based on an input from the driver and outputs it as a corresponding signal to the LIN bus. The processing module 1 detects whether the light pattern corresponding to the current signal is provided on the LIN bus 6 for the lighting device. If this is the case, this signal is converted into a corresponding signal for the internal data bus 2 by means of the microprocessor 102.

The internal data bus 2 can e.g. be an SPI bus. The signals for the SPI bus are preferably generated by the microprocessor 102 by means of software SPI. Software SPI is known per se from the prior art and represents a program library with which any free pins of the microprocessor 102 can be used for signaling on the SPI bus. Alternatively, hardware SPI can also be used. Special SPI pins are provided for signaling on the SPI bus. The use of software SPI has the advantage that a plurality of lines DL and CL can be provided in the internal data bus 2 to control 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 by the fact that it encodes digital data via a voltage difference between two lines.

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

The construction of a single LED unit 3 from Fig. 1 is in detail in Fig. 2 shown. All of the components of the LED unit shown are integrated in a single semiconductor component. 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 to 8-bit shift registers SR0, SR1, SR2, SR3 and SR4 after decoding in the communication interface COM. The from The shift register value SR0 shows the desired overall brightness of the LED unit, whereas the values of the shift registers SR1 to SR4 are used to output the color components of the individual single-color LEDs to produce the desired mixed color. 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 is output via the shift register SR2, the color component of the blue LED 303 is transferred via the shift register 303 and the color component of the white LED 304 is output 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 assigned non-volatile EEPROM memory 402. This memory contains, among other things, calibration data that originate from a calibration process of the LED unit and, for a given standard temperature value of the LED unit, stipulate how the operating currents of the individual single-color LEDs are to be set, so that the overall brightness value coming from the shift register SR0 and the color mixing (ie the relevant 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 receives the current temperature value of a temperature sensor TS, which is integrated in the semiconductor component of the LED unit. A temperature algorithm is stored in the microprocessor which, with access to the memory 402, determines the corresponding operating currents for the above-mentioned standard temperature value and corrects these operating currents appropriately if the current temperature value coming from the temperature sensor TS deviates from the standard temperature value. The correction is designed in such a way that the desired brightness and the desired color location are correctly set in accordance with the values from the shift registers even in the event 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 an effect 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. This correction is based on a temperature value that is determined directly in the LED unit via a temperature sensor integrated in it. This makes a particularly precise temperature measurement guaranteed at the location of the LED unit. In addition, the algorithm for temperature compensation is 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 individually and very precisely adapted to the current temperature.

The operating currents for the individual LEDs 301 to 304 are provided via a voltage regulator RE, which consists of the in Fig. 1 shown voltage supply 5 receives the positive voltage VDD and the negative voltage VSS. The microprocessor 401 also generates a clock for a corresponding oscillator OS, which is fed 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 passed from the microprocessor 401 to the individual generators G1 to G4. The generator G1 uses pulse width modulation to generate the current for the red LED 301, 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 the individual generators generated PWM signals, which reach the single-color LEDs via the current output CO, the appropriate light with the desired brightness and the desired color location is then set for the LED unit 3 in accordance with the signal sent via the internal data bus 2 the LED unit arrives.

The embodiments of the invention described above have a number of advantages. In particular, as part of a temperature compensation, the current temperature value required for this is determined very precisely via a temperature sensor which is integrated in the semiconductor component of a respective multi-color LED unit. The temperature value is thus determined very precisely at the location of the respective multi-color LED unit. In addition, the algorithm for temperature compensation is integrated in the semiconductor component of the respective multi-color LED unit. In other words, integrated logic is used in a multi-color LED module in order to implement temperature compensation. In this way, the desired brightness and the desired color location can be set individually and with high precision for each LED unit depending on the temperature at the installation location of the respective LED unit. To this In this way, a uniform appearance of the LED unit or an LED strip comprising many LED units can be guaranteed over the entire service life.

Reference list

1

Processing module

101

LIN transceiver

102

microprocessor

2nd

internal data bus

3rd

Multi-color LED units

301, 302, 303, 304

Single color LEDs

4th

Microcontroller

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

SR0, SR1, SR2, SR3, SR4

Shift register

TS

Temperature sensor

G1, G2, G3, G4

PWM generators

OS

oscillator

RE

Voltage regulator

VDD, VSS

Tensions

CO

Current output

Claims (9)

1. Illumination device, in particular for a motor vehicle, comprising a plurality of multi-colour LED units (3) with respectively settable brightness and settable colour point, wherein each multi-colour LED unit (3) is an individual semiconductor device with a plurality of single-colour LEDs (301, 302, 303, 304) of different colour and a microcontroller (4), characterized in that the single-colour LEDs (301, 302, 303, 304) and the microcontroller (4) of each multi-colour LED unit (3) are enclosed by a corresponding package of the semiconductor device, wherein a temperature sensor (TS) is integrated in the semiconductor device, which temperature sensor measures an instantaneous temperature value of the respective multi-colour LED unit (3) and makes it available to the microcontroller (4), wherein the microcontroller (4) is set up to control a respective multi-colour LED unit (3) in dependence on the instantaneous temperature value of the respective multi-colour LED unit (3).
2. Illumination device according to Claim 1, characterized in that the microcontroller (4) of a respective multi-colour LED unit (3) is set up to control each single-colour LED (301, 302, 303, 304) of the respective multi-colour LED unit (3) in dependence on the instantaneous temperature value of the respective multi-colour LED unit (3), such that a set colour point and a set brightness are kept constant during operation of the respective multi-colour LED unit (3).
3. Illumination device according to Claim 1 or 2, characterized in that the microcontroller (4) of at least some of the multi-colour LED units (3) is configured to control each single-colour LED (301, 302, 303, 304) on the basis of the control of the operating current of the respective single-colour LED (301, 302, 303, 304) .
4. Illumination device according to one of the preceding claims, characterized in that the microcontroller (4) of at least some of the multi-colour LED units (3) is configured such that, if the instantaneous temperature value exceeds a specified threshold, it reduces the brightness of the multi-colour LED unit (3).
5. Illumination device according to one of the preceding claims, characterized in that the illumination device comprises a plurality of multi-colour LED units (3), which are connected to an internal databus (2), which is coupled to a processing module (1), wherein the processing module (1) is set up to pass internal control commands for setting the brightness and the colour point of the individual multi-colour LED units (3) to the internal databus (2).
6. Illumination device according to Claim 5, characterized in that the processing module (1) is set up to receive external control commands from a motor vehicle databus (6) and convert them to the internal control commands.
7. Illumination device according to one of the preceding claims, characterized in that at least some of the multi-colour LED units (3) comprise one or more RGB-LED units and/or RGBW-LED units.
8. Illumination device according to one of the preceding claims, characterized in that the illumination device is an interior illumination means for mounting in a motor vehicle or an exterior illumination means for mounting on the outside of the motor vehicle.
9. Motor vehicle, comprising one or more illumination devices according to one of the preceding claims.

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