EP3764747A1 - Linear light unit, light source module for such a linear light unit and method for operating such a linear light unit - Google Patents

Abstract

A linear light unit is described with several light source modules 41 connected in series via electrical lines 42, 43, 44, each supplied with a constant current source with direct current, one line being a plus line 42, another being a minus line 43 and another line is a control line 44 and a signal transmitted via the control line 44 is present at the control input of each light source module 41. It is provided that at least one light source module 41 can be controlled in multiple channels, the control line 44 is designed with multiple channels according to the number of channels through multiple individual control lines 44.1, 44.2, that the linear light unit 40 is assigned a number of PWM transmitters 48, 49 corresponding to the influencing variables, wherein a first control voltage is provided by a first PWM transmitter 48 and this first control voltage is used to generate a control voltage for at least two channels, and that each light source module 41 has a PWM attenuator as PWM signal processing (i) for each influencing variable Determining the distance between the switch-on edges and the subsequent switch-off edges of the pulses of the PWM signal, (ii) to generate defined high and low phases that are independent of the PWM signal level and (iii) to provide a DC control voltage that is dependent on the edge distance determined as well as a current sink mod ul with a constant current source and at least one light source controlled by this per channel. A light source module 41 for such a light source unit 40 and a method for operating such a linear light unit 40 are also described.

Description

The invention relates to linear light unit with several light source modules connected in series via electrical lines, each supplied with direct current by a constant current source, one line being a plus line , another line being a minus line and yet another line being a control line and one via the control line transmitted signal is applied to the control line input of each light source module. The invention also relates to a light source module for such a linear light unit and a method for dimming such a linear light unit.

Linear light units are lighting systems in which a large number of individual light source modules are connected in series and / or in parallel one behind the other. Such a light source module typically comprises a multiplicity of individual light sources, for example LEDs. Numerous light source modules can be connected in series to form the linear light unit. In this way, rigid or flexible light strips, light chains or light rails can be formed. These are used for lighting purposes, often to illuminate buildings (architectural lighting) and also for accentuation or to provide a specific lighting design.

To keep the wiring effort low, the light source modules of such a linear light unit are connected in series using three-wire technology. The light sources are operated with direct current. LEDs are typically used for this. For this reason, two of the three lines are used to supply voltage to the load (the light source modules), while the third line represents a control line. A regulated current source (constant current source) is assigned to each light source module or a group of light sources resulting from series or parallel connection To compensate for voltage drops across the supply lines connected in series on the supply lines, which can have a not inconsiderable length. This measure avoids a reduction in the emitted luminous flux that would otherwise occur in the light source modules connected in series, in particular towards the end of the series connection. The control line is at the inputs of the control inputs of the constant current sources.

If such a linear light unit is to be dimmed, pulse width modulation (PWM) of the supply voltage is used in many cases. In this way it is possible to produce the same dimming over all light source units of the linear light unit. In addition, dimming via pulse width modulation of the supply voltage is associated with little effort. However, disadvantages must be accepted with this dimming process. On the one hand, the reaction speed is limited. The reason for this is the numerous series-connected constant current sources, which sometimes have noticeable response times when the supply voltage is switched off, which is why dimming processes can only be implemented with a low pulse width modulation frequency. In addition, it was found that pulse-width-modulated light sources can contribute to discomfort in people who are exposed to the light. The reason for this is the unavoidable modulation artifacts in the luminous flux with a PWM dimming process. The LEDs typically used as light sources pass on the current fluctuations as luminous flux fluctuations without inertia. With pulse-width modulated light sources, individual switch-on and switch-off pulses can sometimes be perceived. A pulse-width-modulated luminous flux can cause interference with displays, for example on cell phones or the like, which are perceived by the user and perceived as annoying.

It is sometimes seen as problematic with PWM dimming controls that low levels of brightness can only be achieved inadequately. Furthermore, it would be desirable if such a linear light unit in a simple Way could be designed to work multi-channel in order to be able to control light source modules multi-channel.

Thus, based on the discussed prior art, the invention is based on the object of proposing a linear light unit, a light source module for such a linear light unit and a method for operating a linear light unit, in which the disadvantages to be accepted in conventional PWM dimming methods are avoided and which is also suitable for being able to be designed with multiple channels.

This object is achieved on the one hand by a generic linear light unit of the type mentioned at the outset, in which the light source modules can be controlled in multiple channels, the control line is designed in multiple channels according to the number of channels, in which the linear light unit is assigned a number of PWM transmitters corresponding to the influencing variables, with a first control voltage is provided by a first PWM encoder and this first control voltage is used to generate a control voltage for at least two channels, and in which each light source module has a PWM signal conditioning (i) for each channel to determine the distance between the switch-on edges from the respective subsequent switch-off edges of the pulses of the PWM signal, (ii) to generate defined high and low phases that are independent of the PWM signal level and (iii) to provide a DC control voltage that is dependent on the edge separation determined and a current sink module with a constant rom source and at least one of this controlled light source per channel.

The aspect of the task directed at the light source module is achieved by a light source module with the features of claim 12.

The method-related aspect of the invention is achieved by a method having the feature of claim 14.

In the following, the design and the mode of operation of a single-channel linear light unit is first described. This makes it easier to understand a linear light unit designed with multiple channels, since the explanations in this regard apply in principle to each channel of a linear light unit operated with multiple channels.

In such a linear light unit, the presence of a constant current source in each light source module is cleverly used. The control of the light sources or the constant current source supplying the light sources of such a light source module takes place via a control line. A pulse-width modulated signal is used as the control signal. To operate the light source modules of this linear light unit, this signal is not used as control information with regard to the level of its level, but only with regard to the distance between a switch-on edge and the subsequent switch-off edge. In this way, the same control information is received by each light source module, even if the level of the PWM control signal should decrease or otherwise be influenced over the distance of the light source modules connected in series. In each light source module, a DC control voltage is generated from this control signal by means of PWM signal processing, which is independent of the PWM signal level and also independent of the frequency of the PWM signals due to the evaluation of the distance between the switch-off edges and the preceding switch-on edges. This direct voltage is generated by generating high and low phases that are defined in terms of their magnitude, depending on the pulse / period ratio with subsequent low-pass filtering.This is possible because an ideal low-pass filtering delivers precisely the direct component of the processed PWM signal which in turn is proportional to the ratio of switch-on time to period duration. This DC control voltage is applied to the input of a current sink module as part of each light source module. The constant current source is controlled by this DC control voltage, namely its arithmetic unit, which is typically designed as an operational amplifier. The light sources of the light source modules are therefore not dimmed via pulse width modulation of the Supply voltage, which is why the presented concept avoids the disadvantages of the prior art, in particular the artifact formation mentioned. In this concept, a commercially available, cost-effective PWM encoder is cleverly used in order to use its PWM signal to generate a control signal for operating a constant current source in each light source module. The currents flowing through the light sources of the light source modules are therefore proportional or approximately proportional to the switch-on duration of the PWM signal and thus the length of the high phases in relation to the period duration.

Edge detection of the PWM signal can be implemented with simple means. According to one embodiment, an n-channel MOSFET is used to generate the PWM signal, since the switching losses are particularly low with this. A switching element is thus used that has only a small voltage drop in the current flow phase. These electronic switching elements usually switch the ground path. This means that the internal resistance of the PWM encoder is significantly different in the two phases.

To enable a voltage to build up when the electronic switching element, typically a MOSFET, is open, a work load, typically designed as a resistor, is required. According to an exemplary embodiment, this working resistor is part of each light source module. Such a load, implemented as a working resistance, for example, can be used for a further purpose. The supply lines and thus also the control line have a capacitive coating primarily due to their length, but also due to their design. The load resistance is adapted to this capacitance in such a way that the time constants resulting from the resistance value and the capacitive coating are sufficiently small to also be able to transmit narrow PWM pulses. The PWM signal has narrow PWM pulses as high phases when the light sources contained in the light source modules are to be dimmed to a high degree.

Each light source module has PWM signal processing and a current sink module. According to one exemplary embodiment, the PWM signal processing is divided into a first PWM signal processing stage and a second PWM signal processing stage following this, with low-pass filtering being carried out in the second PWM processing stage. According to one exemplary embodiment, the first PWM signal processing stage provides for an electronic switching element, for example a transistor, to be controlled via a voltage divider. If a transistor is provided as the electronic switching element of the first PWM signal processing stage, it is advantageous to operate the transistor in the emitter circuit and to control it through the voltage divider. With regard to its division ratio, the voltage divider will be designed in such a way that PWM signals, which are changed in their original level by voltage drops on the lines, lead to a flawless and thus sufficiently accurately detectable formation of the edges of the PWM signal. The input signal is also inverted in this PWM signal processing stage. To improve the switching accuracy of the electronic switching element provided, for example, as a transistor, in this first PWM signal processing stage, a Schottky diode connected to the collector input can be provided. This counteracts the saturation effect of the transistor and ensures constant switching times. At the same time, it is advisable to provide a protective diode by means of which the transistor, as an exemplary electronic switching element, is protected against higher negative voltages in the event of possible incorrect connections.

With such a PWM signal processing stage, a reference voltage is required to operate a load resistor. The working resistance is part of the emitter stage. The reference voltage is preferably as large as possible so that when the transistor is turned on to the maximum, a desaturation voltage, which is small in relation to the supply voltage, remains across the collector-emitter path. In one design of such a light source module, the reference voltage is generated in the current sink module.

The output signal of the first PWM signal processing stage represents the input signal for the second PWM signal processing stage, which is low-pass filtered in this PWM signal processing stage. Different low-pass filters can be used to low-pass filter the control signal. A passive first-order low-pass filter is particularly simple in construction. Such a low-pass filter can be implemented by a voltage divider in connection with a capacitance. The voltage divider is expediently designed so that it is used to adapt to the required voltage ranges of the downstream current sink module.

The DC voltage generated by the signal processing in the first PWM signal processing stage of the PWM signal processing is applied to the input of the voltage-controlled current sink module. This comprises a constant current source and at least one light source controlled by this. Typically, such a current sink module has several or even a multiplicity of individual light sources, which are preferably designed as LEDs. According to one exemplary embodiment, the constant current source of the current sink module has an operational amplifier, the output of which controls a transistor connected as an emitter follower. A measuring resistor switched into the emitter path of this transistor as an exemplary electronic switching element generates a voltage drop. This is proportional to the current flowing through the light sources. This voltage drop is fed to the inverting input of the operational amplifier, typically with the interposition of a further resistor. The control line, however, acts on the non-inverting input of the operational amplifier of the constant current source. In addition, there is a path implemented through a resistor between the stable supply voltage of the operational amplifier and its inverting input. This path is used to compensate for the saturation effects of the switching transistor of the first processing stage as well as offset values of the operational amplifier and thus to ensure that a PWM signal that has the "Off" state represents a safe shutdown of the current flow of the power sources leads. In this way, via the control voltage present on the control line at the non-inverting input of the operational amplifier, i.e. the direct voltage generated by the first PWM signal processing stage, a current flow depending on this voltage and the size of the voltage drop in the non-inverting input of the operational amplifier in Can be set depending on the design of the resistor switched on in these.

In the case of a multi-channel design of such a linear light unit, a control voltage is applied to the several channels as a function of one another. Typically, in such an operation of a linear light unit, several influencing variables have to be set for the desired lighting, such as the brightness and the color temperature. It is provided here that the control voltage for the first influencing variable, for example the brightness, influences the control voltages for the individual channels, for example to generate the desired color temperature of the emitted light. The dependency of the control voltages in the channels takes place against the background that an available service package is set up in accordance with the desired lighting. In the case of a two-channel design of such a linear light unit, tunable white light source modules are provided as part of the light source unit. These each have cold white light sources and warm white light sources. The color temperature emitted by the light source modules then results as a function of the mixing ratio. In such a configuration, the influencing variables are the brightness and the color temperature. The brightness and color temperature are not on different channels. Rather, the influencing variable "color temperature" is applied to two channels, each channel being assigned its own control voltage. In such an embodiment, a first channel is used to control the cold white light sources and a second channel is used to control the warm white light sources. With a three-channel design of such a linear light unit, the Light source modules on three different light sources, can thus be designed, for example, as RGB light source modules.

With such a multi-channel design of the linear light unit, it has a number of PWM transmitters corresponding to the number of influencing variables. If two variables are influenced, namely the brightness and the color temperature, the linear light unit has two PWM transmitters. In contrast to the above-described single-channel design of such a linear light unit, these PWM transmitters do not feed the generated control voltage directly into a current sink of the light source modules - the light sources. Rather, this first generated control voltage serves as the basis for generating a number of new control voltages corresponding to the number of channels. If the light source modules are designed as tunable white light source modules, two new control voltages are generated from the first control voltage generated, which are then used to control the warm white and cold white channels. It is provided that the power package provided by the first control voltage is divided between the two channels described in the aforementioned example. The available performance package is generated by the brightness setting (dimming) as the first control voltage. The control value for one of the two channels of the color temperature in a tunable white version of the light source modules is typically specified in terms of its share by the PWM encoder responsible for the color temperature. The portion of the first control voltage that is provided for the second channel can thus be determined in a simple manner by subtraction, for example by means of a circuit-implemented difference calculator, taking into account the portion specified for the first channel.

The special feature of such a multi-channel, for example two-channel, linear light unit is that it can be implemented solely in terms of circuitry and thus without needing a microcontroller in the light source modules.

In the case of a linear light unit designed, for example, with two channels, the control line is designed with two channels. This means that the control line ultimately has its own line for each channel, which is looped through the light source modules connected in series. If the linear light unit is designed to work more than two channels, the control line has a number of individual control lines corresponding to the number of channels. In the case of linear light units operating in multiple channels, the individual control line present in the prior art is thus implemented by several individual control lines.

The PWM transmitters are not part of the light source modules, but a separate unit in the linear light unit.

Fig. 1:

Eine schematisierte Darstellung nach Art eines Blockschaltbildes einer einkanalig ausgelegten Linearlichteinheit mit einer Vielzahl von in Reihe geschalteten Lichtquellenmodulen,

Fig. 2:

eine Schaltungsanordnung einer Linearlichteinheit mit einem ersten Lichtquellenmodul,

Fig. 3:

eine schematisierte Darstellung entsprechend derjenigen der Figur 1, jedoch darstellend ein Blockschaltbild einer zweikanalig ausgelegten Linearlichteinheit mit einer Vielzahl von in Reihe geschalteten Lichtquellenmodulen,

Fig. 4:

ein Blockschaltbild zur Darstellung der Funktionsweise der zweikanalig ausgelegten Lichtquellenmodule der Linearlichteinheit der Figur 3 und

Fig. 5:

eine Schaltungsanordnung einer zweikanaligen Linearlichteinheit mit einem ersten Lichtquellenmodul.

The invention is described below with reference to the accompanying figures. Show it:

Fig. 1:

A schematic representation in the manner of a block diagram of a single-channel linear light unit with a large number of light source modules connected in series,

Fig. 2:

a circuit arrangement of a linear light unit with a first light source module,

Fig. 3:

a schematic representation corresponding to that of Figure 1 , but showing a block diagram of a two-channel linear light unit with a large number of light source modules connected in series,

Fig. 4:

a block diagram to illustrate the mode of operation of the two-channel light source modules of the linear light unit of Figure 3 and

Fig. 5:

a circuit arrangement of a two-channel linear light unit with a first light source module.

Based on Figures 1 and 2 a single-channel linear light unit is described first. This simplifies the understanding of a two-channel linear light unit described below.

A single-channel linear light unit 1 comprises a multiplicity of light source modules 2 connected in series with one another. The light source modules 2 are connected to one another by means of three-wire wiring. Two of these lines 3, 4 are provided for the voltage supply. Line 3 represents the plus line and line 4 represents the minus line. The minus line 3 forms the ground line. A third line is a control line 5.

A PWM transmitter 6 is also part of the linear light unit 1. Its output signal is applied to the control line 5. The PWM signal generated by the PWM transmitter 6 is therefore used to control the individual light source modules 2. The PWM transmitter 6, together with a power supply 7, is part of a supply unit 8. The light source modules 2 are connected to this in series with one another.

An exemplary circuit diagram of the supply unit 8 and a light source module 2 connected to it is shown in FIG Figure 2 shown. The PWM transmitter 6 has a power supply 9 and a MOSFET 10 as a switching element. The PWM transmitter 6 is used to switch the ground path of the linear light unit 1. A resistor 11 is connected to the current-conducting branch. The resistor 11 causes the Internal resistance of the PWM encoder 6 in the on-phase (high phase) differs significantly from the off-phase (low phase).

The light source module 2 is connected to the power supply 7 of the supply unit 8 and with its control input 12 to the control line 5. The control line 5 is looped through in the light source module 2, as are the supply lines 3, 4. The lines 3, 4, 5 looped through these lines are in the row of light source modules 2 in the Figure 2 shown Light source module 2 connected or connectable light source module 2 downstream.

The light source module 2 has a PWM signal conditioning 13 and a current sink module 14. These two components of the light source 2 are typically arranged on a common circuit board. The PWM processing 13 comprises a first PWM signal processing stage 15. This first PWM signal processing stage 15 initially comprises a working resistor 16 for the PWM transmitter 6. This working resistor 16 enables a voltage to be built up when the MOSFET 10 of the PWM transmitter 6 is closed is. Part of the first PWM signal processing stage 15 is a voltage divider which, in the exemplary embodiment shown, is formed from resistors 17 and 18. This voltage divider controls a transistor 19 operated in the emitter circuit. A Schottky diode 20 is connected in parallel with the branch of the voltage divider formed by the resistor 17. This counteracts the saturation effect of transistor 19, which is designed as a bipolar transistor in the illustrated embodiment. At the same time, the Schottky diode 20 ensures at least approximately the same switching times. The node in the voltage divider formed by the resistors 17, 18 is connected to the base of the transistor 19. This first PWM signal processing stage 15 also has a protective diode 21, by means of which the base-emitter path of the transistor 19 is protected against higher negative voltages in the event of possible incorrect connections. A working resistor 22 is switched into the emitter stage. The working resistor 22 draws its working voltage from a reference voltage generator 23, which is part of the current sink module 14 in the illustrated embodiment. The reference voltage generation 23 comprises a resistor 24 which is connected in series with a Schottky diode 24.1 and a capacitor 25 connected in parallel with this.

In order to provide a large control range, the reference voltage provided by the reference voltage generator 23 is as large as possible, thus even when the transistor is turned on to the maximum 19 a desaturation voltage remains across the collector-emitter path.

The first PWM signal processing stage 15 is followed by a second PWM signal processing stage 26. The input of the second PWM signal processing stage 26 is connected to the collector of the transistor 19. The second PWM signal processing stage 26 is designed in the illustrated embodiment as a passive low-pass filter of the first order and has a voltage divider provided by the resistors 27, 28 and a capacitor 29 connected in parallel to the voltage divider grid provided by the resistor 28. The ratio is of the branches of the voltage divider provided by the resistors 27, 28 are designed so that the DC voltage present at the output of the PWM processor 13 or its second PWM signal processing stage 26 is adapted to the required voltage ranges of the current sink module 14.

In this way, the PWM signal conditioning 13 generates a DC voltage with the two PWM signal conditioning stages 15, 26, the magnitude of which depends directly on the ratio of the switch-on time to the period duration of the PWM signal generated by the PWM transmitter 6. It is important that the level of the direct current generated in this way is independent of the level of the PWM signal. Changes in the level of the PWM signal over the possibly relatively long route of the control line 5 therefore do not influence the activation of the respective subsequent light source module 2. There is no change in the distance between the switch-on edges and the respective switch-off edges, even with a longer control line.

The current sink module 14 has a plurality of LEDs 30 as light sources. The LEDs 30 receive their supply voltage from a constant current source as parts of the current sink module 14. The constant current source is in the illustrated embodiment by an operational amplifier 31 and a transistor 32, which in the illustrated embodiment is also a bipolar transistor is executed, formed. The emitter current of transistor 32 produces a voltage drop across a measuring resistor 33 located in its emitter path. This is proportional or at least approximately proportional to the current flowing through the LEDs 30. This voltage drop is fed to the inverting input 34 of the operational amplifier 31 via a resistor 35. The control voltage generated by the PWM signal processor 13 is fed in at the non-inverting input 36 of the operational amplifier 31. In this way, a current flow is provided, the size of which corresponds to the ratio of the control voltage applied to the non-inverting input 36 and the resistance value of the resistor 35. Another resistor 37, which is connected to the branch of the reference voltage generation 23, is typically several powers of ten greater than the resistance value of the resistor 35 in terms of its resistance value. Therefore, it does not influence the above-described method for power supply, at most not to a significant extent.

From the description of this linear light unit 1 it becomes clear that in this concept, despite the use of a PWM transmitter 6, the energy supply of the light sources 30 in the light source modules 2 is independent of the PWM signal level.

Figure 3 FIG. 4 shows a block diagram of a further linear light unit 40, which is constructed in principle like the linear light unit 1 of FIG Figure 1 . As with the linear light unit 1, the light source modules 41 are connected in series and connected to a plus line 42 and a minus line 43. The light source modules 41 are designed to work with two channels. The control line 44 in this linear light unit 40 is therefore implemented by two individual lines 44.1, 44.2. Each individual control line 44.1, 44.2 has a control voltage applied to it for the respective channel controlled by the control line 44.1 or 44.2. The control voltage is provided by a PWM transmitter unit 45. In the exemplary embodiment shown, the PWM transmitter unit comprises two PWM transmitters, one PWM transmitter in each case for providing a control voltage for a control variable is provided. In the case of the linear light unit 40, a PWM transmitter is used to provide a control voltage corresponding to the desired brightness. Another PWM encoder provides a control voltage for the color temperature. This is transmitted in two channels to the light source modules 41 via the individual control lines 44.1 or 44.2.

The PWM transmitter unit 45 is typically part of a supply unit 46 which also includes a power supply 47.

Figure 4 illustrates the mode of operation of the linear light unit 40. A first PWM transmitter 48 is connected to the power supply 47. A first control voltage is provided via this, namely that which is responsible for the brightness control of the light source modules 41. The dimming value (PWM value) is specified by the user. The control voltage generated at the output of the PWM transmitter 48 according to the statements about the single-channel linear light unit of the above-described embodiment represents the input voltage for a second PWM transmitter 49. This generates a control voltage with regard to the color temperature desired by the user or specified by a controller. In the illustrated embodiment, the light source modules 41 are designed as tunable white light source modules. These are thus controlled in their one channel with a control voltage for the cold white light component and via the second channel with regard to their warm white light component. In the illustrated embodiment, the control voltage generated for the cold white light component is supplied to the light source modules 41 via the individual control line 44.1 and the control voltage generated for the warm white light component via the individual control line 44.2. The first control voltage generated by the PWM transmitter 48 represents a power package which, depending on the desired color temperature, is divided as control voltages between the two individual control lines 44.1 and 44.2. The power package provided by the first PWM transmitter 48 is divided up in each light source module 41, which is shown in FIG Figure 4 is indicated, as is the supply unit 46.

For the purpose of dividing the power package between the two channels, the illustrated embodiment provides that the control voltage on the one channel, here: the cold white light channel, which is proportionally specified, and the control voltage for the warm white light channel using a difference generator 50 as a function of the predetermined cold white light component is generated.

A circuit structure for implementing the above-described mode of operation of the linear light unit 40 is shown in FIG Figure 5 shown.

The circuit structure essentially corresponds to the circuit structure of the linear light unit 1, as shown in FIG Figure 2 is shown, with the in Figure 2 The circuit shown is provided twice due to the described design of the linear light unit 40.

Since the light source modules 41 are tunable white light source modules 41, each light source module 41 has two current sink modules, one current sink module 51 having warm white LEDs 52 and a second current sink module 53 with cold white LEDs 54. Each light source module 41 also has two auxiliary voltage supplies 55, 54. A first auxiliary voltage supply 55 provides a voltage supply of 24 V. A second auxiliary voltage supply 56 provides an auxiliary voltage of 5V. The voltage source 47 of the supply unit 46 supplies a voltage of 48 V.

The control voltage is generated in the same way as is described for the single-channel linear light unit 1. The signal (brightness) generated by the PWM transmitter 48 is processed in a PWM attenuator 57 to generate the first control voltage. The PWM attenuator 57 comprises the PWM signal processing stages also described for the linear light unit 1 or its light source modules 2. The PWM attenuators thus also include a low-pass filter, which is designed as a first-order passive filter. At the output 58 of the PWM attenuator 57 is the in The first control voltage generated depending on the set dimming value. This is fed into a second PWM attenuator 60 via a supply line 59. The second PWM attenuator 60 is used to provide a control voltage for the second influencing variable, namely the color temperature. The input side of the PWM attenuator 60 is connected to the output of the PWM transmitter 49.

The control voltage present at the output 58 of the PWM attenuator 57 is also fed into the subtractor 50, specifically into the non-inverting input 61 of its operational amplifier 62. The output of a buffer stage 64 is present at the inverting input 63. The buffer stage 64 is connected to the inverting input 66 of the operational amplifier 67 of the cold white current sink module 53 via a connection line 65. In this way, the control voltage for the warm white light channel of the light source module 41 is dependent on which portion of the received power package is provided for the control of the current sink module 53 used to generate cold white light.

The auxiliary voltage supply 24 is implemented in the illustrated embodiment as a simple linear regulator with buffering on the output side. The auxiliary voltage supply 56 for providing the auxiliary voltage of 5 V is also implemented as a simple linear regulator with buffering on the output side. Because the auxiliary voltage supply 55 is connected upstream of the auxiliary voltage supply 56, an excellent screening effect is also achieved.

The buffer stage 64 is designed as a buffer amplifier and ensures a low-impedance supply of the cold white light control voltage. The buffer stage 64 ensures that the unbuffered voltage is separated from the low-impedance input stage of the difference generator 50. With sufficiently precise dimensioning of the difference former 50, the buffer stage 64 can in principle be dispensed with.

The circuit of the difference calculator 50 is dimensioned such that the voltage at the resistor 68, which is proportional to the voltage present at the output 58 of the PWM attenuator 57, is included in the difference calculation with a factor of 2. This allows the non-inverting input 61 of the operational amplifier 62 to be used without a further ground path. The voltage divider formed with the resistor 68 due to the further resistor 69 is halved in terms of the ground resistance compared to the ground resistance of the voltage divider of the PWM attenuator 60 formed by the resistors 70, 71, so that roughly half the voltage at the resistor 68 drops. In this way, the doubling of the non-inverting path is compensated for.

In a further development in the embodiment described, it is provided that the light source modules 41 are designed to be able to control a control voltage for monochrome assemblies as part of the linear light unit. In such a configuration, monochrome light source modules are also switched into the row of light source modules 41. In the case of the monochrome light source modules, the PWM attenuator 57 is used without its operational amplifier. It goes without saying that a corresponding re-dimensioning of the components is then necessary. In this way, monochrome light source modules and tunable white light source modules can be placed mixed within a linear light unit. The PWM transmitter 48 responsible for the brightness then controls all light source modules equally, while the PWM transmitter 49 responsible for the color temperature only influences the tunable white light source modules.

The invention has been described on the basis of exemplary embodiments. Without departing from the scope of the applicable claims, there are numerous other possibilities for a person skilled in the art to implement the invention without this having to be explained in detail in the context of these explanations. <b> List of reference symbols </b> 1 Linear light unit 33 Measuring resistor 2 Light source module 34 Inverting input 3 plus line 35 resistance 4th minus line 36 inverting input 5 Control line 37 resistance 6th PWM encoder 7th Power supply 40 Light source unit 8th Supply unit 41 Light source module 9 Power supply 42 plus line 10 MOSFET 43 minus line 11 resistance 44 Control line 12 Control input 44.1 Individual control line 13 PWM signal processing 44.2 Individual control line 14th Current sink module 45 PWM encoder unit 15th first PWM signal processing stage 46 Supply unit 16 Work resistance 47 Power supply 17th resistance 48 PWM encoder 18th resistance 49 PWM encoder 19th transistor 50 Difference generator 20th Schottky diode 51 Current sink module 21st Protection diode 52 Warm white LED 22nd Work resistance 53 Current sink module 23 Reference voltage generation 54 Cold white LED 24 resistance 55 Auxiliary emergency supply 24.1 Schottky diode 56 Auxiliary power supply 25th capacitor 57 PWM attenuator 26th second PWM signal processing stage 58 exit 27 resistance 59 supply line 28 resistance 60 PWM attenuator 29 capacitor 61 non-inverting input 30th Light source, LED 62 Operational amplifier 31 Operational amplifier 63 inverting input 32 transistor 64 Buffer level 65 Connecting cable 66 inverting input 67 Operational amplifier 68 resistance 69 resistance 70 resistance 71 resistance

Claims (16)

Linear light unit with several light source modules (41) connected in series via electrical lines (42, 43, 44), each supplied with a constant current source with direct current, one line being a plus line (42), another a minus line (43) and yet another line is a control line (44) and a signal transmitted via the control line (44) is present at the control input of each light source module (41), characterized in that at least one light source module (41) can be controlled in multiple channels, the control line (44) According to the number of channels through several individual control lines (44.1, 44.2), the linear light unit (40) is assigned a number of PWM transmitters (48, 49) corresponding to the influencing variables, with a first PWM transmitter (48) a first control voltage is provided and this first control voltage is used to generate a control voltage for at least two channels, and that each light source module (41) a PWM attenuator (57, 60) as PWM signal processing (i) for determining the distance between the switch-on edges and the respective subsequent switch-off edges of the pulses of the PWM signal, (ii) for generating from the Defined high and low phases independent of the PWM signal level and (iii) for providing a DC control voltage dependent on the determined edge distance and a current sink module (51, 53) with a constant current source and at least one light source (52, 54) per channel controlled by this having. Linear light unit according to Claim 1, characterized in that the PWM transmitters (48, 49) have a MOSFET as a switching element. Linear light unit according to claim 1 or 2, characterized in that the PWM signal processing for each Influencing variable in a first PWM signal processing stage comprises a voltage divider which controls an electronic switching element. Linear light unit according to Claim 3, characterized in that a transistor operated in an emitter circuit is controlled by the voltage divider. Linear light unit according to Claim 4, characterized in that a Schottky diode is integrated into the PWM signal processing to counteract a saturation effect of the transistor. Linear light unit according to one of Claims 3 to 5, characterized in that the PWM signal processing has a low-pass filter in a second PWM signal processing stage. Linear light unit according to Claim 6, characterized in that the low-pass filter is designed as a passive filter of the first order. Linear light unit according to one of Claims 1 to 7, characterized in that each current sink module (51, 53) comprises an operational amplifier (67) whose output signal controls an electronic switching element, for example a transistor designed as a bipolar transistor. Linear light unit according to one of Claims 1 to 8, characterized in that the multi-channel light source modules (41) each have a plurality or a plurality of LEDs (52, 54) as the light source for each channel. Linear light unit according to one of Claims 1 to 9, characterized in that the control voltage generated with the first PWM transmitter (48) and the PWM attenuator (57) assigned to it is fed into the PWM attenuator via a supply line (59) (60) is fed, the input of which is connected to a second PWM encoder (49). Linear light unit according to claim 10, characterized in that the non-inverting input (66) of the operational amplifier (67) of a current sink module (53) acts on the non-inverting input (63) of the operational amplifier (62) of a subtractor (50) via a connecting line (65) , wherein the output of the differentiator (50) is connected to the input of another current sink module (51). Light source module for a light source unit according to one of claims 1 to 11, characterized in that at least one light source module (41) can be controlled in multiple channels, the control line (44) is designed in multiple channels according to the number of channels through multiple individual control lines (44.1, 44.2), that the Linear light unit (40) is assigned a number of PWM transmitters (48, 49) corresponding to the influencing variables, a first control voltage being provided by a first PWM transmitter (48) and this first control voltage for generating one control voltage for at least two Channels, and that each light source module (41) has a PWM attenuator (57, 60) as PWM signal processing (i) for determining the distance between the switch-on edges and the respective subsequent switch-off edges of the pulses of the PWM signal, (ii) for generating defined high and low phases that are independent of the PWM signal level and (iii) for area It provides a DC control voltage dependent on the determined edge distance and a current sink module (51, 53) with a constant current source and at least one light source (52, 54) controlled by this per channel. Light source module according to Claim 12, characterized in that the light source module (41) has the features of one or more of Claims 3 to 11. Method for operating a linear light unit with a plurality of light source modules (41) connected in series via electrical lines (42, 43, 44), each supplied with a constant current source with direct current, one line being a plus line (42), another being a minus - Line (43) and yet another line is a control line (44) and a signal transmitted via the control line (44) is present at the control input of each light source module (41), characterized in that a number of PWM signals corresponding to the number of influencing variables and fed into the control line (44) and in each light source module (41) depending on the distance between the switch-on edges of each PWM signal and the respective subsequent switch-off edges, a direct current signal proportional to the switch-on duration of the PWM signal is generated, with which after the division of the direct current signal corresponding to an influencing variable into one of the number of The constant current source in each light source module (41) for operating the light sources (52, 54) located therein is controlled by a number of new direct current signals (control voltages) corresponding to the changing channels. Method according to Claim 14, characterized in that a first control voltage is provided by a first PWM transmitter (48) responsible for a first influencing variable, which control voltage defines the power package that is generated depending on the signal of the PWM signal provided for the further influencing variable. Encoder (49) is distributed to the individual control line (44.1, 44.2) provided for each control channel. Method according to Claim 15, characterized in that the proportion of one channel is based on this further influencing variable the provided power package is specified and the control voltage for the second channel is determined by subtraction taking into account the proportion specified for the first channel.

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