EP3235349B1 - Brightness control for a light signal system - Google Patents

Description

The invention relates to a light signal system with a circuit arrangement for adjusting the brightness of signal transmitters of the light signal system. The invention also relates to a method for setting the brightness of a light signal system.

Light signal systems, also known as light signal systems, are used to control road traffic. They arrange a certain behavior for road users by emitting controlled light signals. These traffic signs, which differ in shape and color, each have a different meaning and only radiate against the direction of travel of the traffic to be regulated. There are various reasons for using traffic lights, for example to improve the flow of traffic and to defuse dangerous or dangerous traffic situations. In road traffic, these are in particular junctions and bottlenecks, e.g. at construction sites or bridges. Depending on the change in the light conditions prevailing in the area of the respective light signal system, the light signals displayed by the light signal system can be seen better or worse. In particular in the case of lighting conditions that fluctuate over the time of day, that is to say for example in the case of light signal systems arranged outdoors, there is a need to adapt the brightness of the signal transmitters of the light signal system to the respective light conditions. For example, signaling devices that are too weakly illuminated during the day can easily be misinterpreted when there is strong sunlight, and signaling devices that are too strong can dazzle road users at night.

Thus, there is a requirement for traffic light systems to change the brightness of the signal heads in order to adapt them to the ambient brightness. Furthermore, by adapting the Brightness of the signaling device, electrical energy can also be saved, since the light signals do not have to shine so brightly at night in order to be easily recognized and differentiated. Changing the brightness of lighting units is also called dimming.

So far, the dimming of traffic lights was achieved by allowing the control to vary the voltage with which the signal generators were operated in one or more stages. Usual operating voltages are, for example, 230V for full brightness and 150V for reduced brightness. Such a procedure is particularly easy to implement when using incandescent lamps for the signal transmitter, since the incandescent lamps automatically shine darker at low voltage. The brightness of light-emitting diodes, on the other hand, depends on the strength of the electric current flowing through them. In the case of signal transmitters with light-emitting diodes, additional LED driver logic must therefore be installed, which detects the lower supply voltage and reduces the current through the light-emitting diodes, so that the light output is reduced.

In both cases, dimming is conventionally implemented centrally using different supply voltages for different brightnesses of the signal generators. For this purpose, at least one additional transformer or several power supply units are installed in the power supply unit of the traffic light system and a switch is made between the individual voltages of the various voltage converters in order to obtain different supply voltages for different brightnesses.

The additional voltage converters are expensive and take up a lot of space. In addition, with an optional dimming function, there is always the need to install additional hardware, ie an additional voltage converter, in the traffic light system, even if the dimming function is not required at all.

In US 2012/0 280 638 describes an LED-based lighting unit that can be used as a replacement for a conventional light bulb. PLC technology is used to control the energy supply to the lighting unit.

In EP 2 466 996 A2 describes a lighting system for illuminating interiors, wherein several lighting units are connected in series with one another.

In WO 2011/056 242 A1 a control circuit for controlling lighting units is described.

In US 2013/270 998 A1 a control of pixel groups with individual pixels with different pixels is described.

In CN 103 533 717 a control circuit of an LED lighting device is described.

In KR 101 317 462 B1 describes a tunnel lighting system.

In EP 1 323 976 A2 describes interior lighting that is adapted to natural lighting conditions.

In US 2006/0 056 855 A1 describes the control of the luminosity of lighting units with the aid of a transmission of control information via a power supply cable.

In WO 2008/001 262 A1 a control of a lighting behavior of a lighting unit with the aid of a pulsed signal is described.

In WO 2014/060 853 A1 is a brightness control of a lighting device by an amplitude modulation of a described as a carrier signal used power supply signal with a three-phase AC voltage.

In WO 2013/061 206 A2 a brightness control of a lighting device by amplitude modulation of an energy supply signal used as a carrier signal with an alternating voltage is described.

In US 2008/258 695 A1 a switching unit for switching between a plurality of light emitting units is described.

In US 2013/009 553 A1 describes a lighting system with a multiplicity of light-emitting units which are arranged spatially separated from one another. A control unit is used to vary the number of luminous units depending on external circumstances.

It is therefore an object of the present invention to develop a light signal system with a dimming function which is more economical, flexible and space-saving. This object is achieved by a light signal system according to claim 1 and a method for setting the brightness of signal transmitters of a light signal system according to claim 11.

DE102007047847 A1 discloses a traffic light system according to the preamble of claim 1.

The light signal system according to the invention has a circuit arrangement for setting the brightness of signal transmitters of the light signal system. The circuit arrangement has a voltage supply interface for receiving an electrical supply voltage. The voltage supply interface can be, for example, a power connection for a supply voltage, such as a 230V AC voltage.

The circuit arrangement also has a voltage conversion unit for generating a carrier signal as a DC voltage signal by converting the electrical supply voltage into an electrical voltage of a carrier signal. A voltage conversion unit should be understood to mean a unit which converts an electrical voltage into an electrical voltage with a different voltage value or a different voltage type. In the process of converting the electrical supply voltage into an electrical voltage of a carrier signal, for example, an alternating voltage with a certain voltage value can be converted into an alternating voltage with a different voltage value or an alternating voltage can be converted into a direct voltage or vice versa.

The circuit arrangement further comprises a control data receiving unit for receiving a control signal, the control signal comprising information relating to a brightness of the light signal system to be set. The circuit arrangement also has a modulation signal generation unit for generating a modulation signal as a function of the received control signal. For example, the modulation signal generating unit is electrically connected to the control data receiving unit or comprises the control data receiving unit in order to receive the control signal from the control data receiving unit and to generate a modulation signal as a function of the detected control command.

The circuit arrangement also comprises a modulator unit for modulating the carrier signal with the modulation signal to form a modulated control signal for controlling the brightness of the signal transmitter. For example, the modulator unit is electrically connected to the modulation unit in order to receive the modulation signal therefrom. Furthermore, the modulator unit is also at least indirectly electrically connected to the voltage conversion unit in order to receive the carrier signal therefrom, which is converted into a control signal in the modulator unit together with the modulation signal. Included the term modulator unit is intended to encompass all types of units that can combine two signals with one another in such a way that the two signals can also be broken down into their output signals again. The modulator unit should therefore also be able to be, in particular, a switch which is controlled by the modulation signal and modulates the carrier signal through this switching process.

A signal transmitter in connection with the light signal system according to the invention is to be understood as a unit which outputs a signal that can be detected by external devices or people, such as road users, and interpreted with regard to information relevant to them. For example, the signal from a signal transmitter includes an instruction or a warning that can be understood or further processed by the persons or devices concerned.

Since the signal generators are controlled with the aid of a modulated supply voltage in the light signal system according to the invention, additional channels for separate data transmission for controlling the signal generators are saved. In addition, in comparison to the conventional circuit arrangements in which the signal generators are controlled with the aid of a plurality of transformers or voltage converters, at least some of these cost-intensive and space-consuming components are saved.

The light signal system according to the invention thus has a circuit arrangement for setting the brightness of the signal transmitters of the light signal system. The circuit arrangement has a signal transmitter device which has the signal transmitter, each signal transmitter having a demodulation unit which is set up to receive the modulated control signal from the circuit arrangement and to demodulate it into the modulation signal and the carrier signal. The signal generators are designed as so-called intelligent signal generators, which make it possible to send digital telegrams or statuses from the control, ie the circuit arrangement, to the signal transmitter via a modulation of the supply voltage. The intelligent control in the signal transmitter regulates the light output depending on the information content of the digital telegram. Part of the intelligent signal transmitter is also a demodulator which analyzes the modulated signal received by the controller in such a way that the information contained relating to the brightness of the signal transmitter can be recorded and further processed by the signal transmitter.

Furthermore, the light signal system according to the invention also has a signal transmitter switching unit which is connected between the circuit arrangement and the signal transmitter device and is set up to switch between different signal transmitters. For example, the individual signal transmitters are warning lights with different meanings. The signal transmitter switching unit is now set up to switch between the different warning lights and to electrically connect the different signal transmitters to the circuit arrangement or to electrically disconnect the different signal transmitters from the circuit arrangement in order to output various warning information or instructions.

In the method according to the invention for setting the brightness of a light signal system, a control signal is received, the control signal comprising a brightness of the light signal system to be set. Furthermore, a carrier signal is generated as a DC voltage signal by converting a supply voltage into an electrical voltage of a carrier signal. In addition, a modulation signal is generated as a function of the received control signal and the carrier signal is modulated with the modulation signal to form a modulated control signal for controlling the brightness of the signal generator.

The essential components of the circuit arrangement of the light signal system according to the invention can be designed predominantly in the form of software components. This applies in particular to the modulation signal generation unit and the modulator unit. In principle, however, these components can also be implemented in part, in particular when particularly fast calculations are concerned, in the form of software-supported hardware, for example FPGAs or the like. Likewise, the required interfaces, for example when it is only a matter of transferring data from other software components, can be designed as software interfaces. However, they can also be designed as hardware-based interfaces that are controlled by suitable software.

A largely software-based implementation has the advantage that circuit arrangements already used to set the brightness of signal transmitters of a light signal system can be easily retrofitted by a software update in order to work in the manner according to the invention. In this respect, the object is also achieved by a computer program product which can be loaded directly into a memory device of a traffic light system, with program sections to carry out all steps of the method according to the invention when the program is being carried out in the traffic signal system.

The dependent claims and the following description each contain particularly advantageous configurations and developments of the invention. In particular, the claims of one claim category can also be developed analogously to the dependent claims of another claim category.

The light signal system according to the invention preferably has an additional switch between the voltage conversion unit and the modulator unit. The additional switch can be used to connect and disconnect the circuit arrangement from the supply voltage or the carrier voltage.

In a preferred embodiment of the light signal system according to the invention, the modulation signal generation unit is set up to generate a sinusoidal signal as the modulation signal. A sinusoidal signal can be used, for example, to frequency modulate a carrier signal. The information to be transmitted is contained in the modulated frequency of the carrier signal.

For example, the sinusoidal signal can have a frequency of 1 kHz for setting a normal brightness and a frequency of 2 kHz for a weaker brightness.

In principle, the frequencies can be freely selected, in practice they are usually in the order of magnitude of 100 Hz to a maximum of 10 kHz. The frequency deviation, i.e. the difference between the two modulation frequencies, can also be selected as required. However, correct demodulation in the signal generator with a small frequency deviation is more complex, so that a sufficient frequency deviation is preferred.

In addition, the modulation is not limited to sine or square functions. A signal with a triangular shape, a sawtooth shape or any other arbitrarily selectable signal shape could just as well be used for this purpose.

Alternatively, the modulation signal generation unit can be set up to generate a square-wave signal as the modulation signal.

In a particularly preferred embodiment of the light signal system according to the invention, the modulator unit is designed in this way controlled so that no square-wave signal is modulated for setting a normal brightness and a modulation of the electrical voltage of the signal generator is carried out with a square-wave signal with a frequency of 1 kHz for a weaker brightness. For example, the modulation unit can be controlled in such a way that it outputs a signal other than zero to the modulator unit only during the time segments during which the brightness is dimmed.

In a variant of the light signal system according to the invention that is particularly easy to implement, the modulator unit is designed as a simple switch. The switch can, for example, be implemented as a commercially available high-side switch (from the Smart High Side Switch family from Infineon). In this case, the switch is controlled with the aid of the modulation signal of the modulation unit and switched according to the amplitude of the modulation signal. In this way, for example, a square-wave signal with the frequency of the modulation signal and the amplitude of the carrier signal can be generated as a control signal for controlling the signal generator.

In a particularly practical embodiment of the light signal system according to the invention, the voltage conversion unit is set up to transform the supply voltage into an electrical direct voltage of the carrier signal. The carrier signal to be modulated is designed as a DC voltage signal in this case.

In addition, the light signal system according to the invention can have an amplitude swing setting unit which is set up to set an amplitude of the modulated control signal. By adjusting the amplitude of the modulated control signal, the efficiency and interference immunity of the signal transmission can be adjusted. In this way, the arrangement can be adapted to specific environmental conditions and requirements.

The amplitude swing setting unit can, for example, have a diode path or a series regulator which bridges the modulator unit. In other words, the components of the amplitude swing setting unit of the modulator unit, which is designed in particular as a simple switch, are connected in parallel so that a signal is also present at the output of the circuit arrangement according to the invention in the phase in which the switch is blocked, the amplitude of which is from the impedance of the components of the amplitude deviation adjustment unit depends.

In a particularly energy-saving variant, the light signal system according to the invention can also have a clock control unit which is set up to define a pulse duty factor with which the carrier signal is modulated with the modulation signal. In this case, the circuit arrangement preferably also has a signal multiplication unit or mixer unit which is set up to mix, in particular to multiply, a clock signal generated by the clock control unit with the modulation signal. The duty cycle of the clock signal defines the period of time for which the carrier signal is modulated. For example, it may be sufficient to modulate the carrier signal only for a sub-interval of each time slot or a system time interval, since, for example, the signal generators only scan the control signal at certain time intervals and no information is recorded by the signal generators in between. This time interval can be, for example, a system time interval or a time slot. A specific time slot is a fixed time interval that is repeated within the framework of the system time.

FIG 1

eine herkömmliche Lichtsignalanlage mit einem Dimm-Transformator,

FIG 2

eine herkömmliche Lichtsignalanlage mit zwei unterschiedlichen zuschaltbaren Spannungswandlern,

FIG 3

eine Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung,

FIG 4

eine Schaltungsanordnung einer Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung zum Erzeugen eines frequenzmodulierten Signals,

FIG 5

eine Schaltungsanordnung einer Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung zum Erzeugen eines rechteckmodulierten Signals,

FIG 6

eine Schaltungsanordnung einer Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung mit einem einfachen Schalter als Modulator,

FIG 7

die Schaltungsanordnung der FIG 6 mit einem zusätzlichen Überbrückungselement zum Einstellen eines Amplitudenhubs des modulierten Signals,

FIG 8

eine Schaltungsanordnung einer Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung, welche hinsichtlich Verlustleistung und Störemission optimiert ist,

FIG 9

den zeitlichen Verlauf eines Ansteuerungssignal, welches von der Schaltungsanordnung der Figur 8 erzeugt wurde,

FIG 10

ein Flussdiagramm, welches ein Verfahren zum Einstellen der Helligkeit einer Lichtsignalanlage gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht.

The invention is explained in more detail below with reference to the attached figures on the basis of exemplary embodiments. Show it:

FIG 1

a conventional traffic light system with a dimming transformer,

FIG 2

a conventional traffic light system with two different switchable voltage converters,

FIG 3

a traffic light system according to an embodiment of the invention,

FIG 4

a circuit arrangement of a light signal system according to an embodiment of the invention for generating a frequency-modulated signal,

FIG 5

a circuit arrangement of a light signal system according to an embodiment of the invention for generating a square-modulated signal,

FIG 6

a circuit arrangement of a light signal system according to an embodiment of the invention with a simple switch as a modulator,

FIG 7

the circuit arrangement of the FIG 6 with an additional bridging element for setting an amplitude swing of the modulated signal,

FIG 8

a circuit arrangement of a light signal system according to an embodiment of the invention, which is optimized with regard to power loss and interference emission,

FIG 9

the temporal course of a control signal which is generated by the circuit arrangement of the Figure 8 was generated,

FIG 10

a flowchart showing a method for adjusting the brightness of a traffic light system illustrated according to an embodiment of the invention.

FIG 1 shows a conventional dimmable light signal system 20 with a dimming transformer 6. The light signal system 20 comprises a voltage supply circuit 1 which is used to provide a supply voltage V _supp suitable for a specific brightness of a signal transmitter. In addition, the light signal system 20 comprises a lamp switching device 2, which is used to switch between different signal transmitters of a signal transmitter unit 3. For example, the signal transmitter unit 3 comprises a signal transmitter 3a for red light, a signal transmitter 3b for yellow light and a signal transmitter 3c for green light.

The voltage supply circuit 1 comprises a voltage supply interface 15 which serves as a connection to a voltage supply line 4, for example with a supply voltage of 230V. Within the voltage supply circuit 1, a line 5 branches off from the voltage supply line 4 to a dimming transformer 6. The dimming transformer 6 transforms the voltage V _supp of 230V, for example, present _{at its input 6a, into a dimmed signal voltage V sig} . The signal voltage V _{sig present} at the output 6b is switched from a first signal voltage changeover switch 8 to a signal line 7 between the voltage supply circuit 1 and the lamp switching device 2 as required. That is, the first signal voltage changeover switch 8 is switched to pass when a signal transmitter of the signal transmitter unit 3 is to shine with a reduced brightness. In addition, a second signal voltage changeover switch 9 is also connected between the supply voltage line 4 and the signal line 7, which is switched to open in the event that no dimming function is desired. The two signal voltage changeover switches 8, 9 are switched alternately. If, for example, the first signal voltage changeover switch 8 is switched through, then the second signal voltage changeover switch 9 locked and vice versa. In this way, V _sig can be switched back and forth between two different signal voltages.

The lamp switching device 2 has three lamp switches 10, 11, 12, corresponding to the number of signal transmitters 3a, 3b, 3b of a signal transmitter unit 3, with which a signal voltage V _sig can be switched to one of the signal transmitters 3a, 3b, 3b. It is also possible to switch the signal voltage V _sig to several signal transmitters at the same time if several signal transmitters are to light up at the same time. This is the case, for example, in the preparation phase for clearing a passage through the traffic signal system 20, that is to say for example in the transition from the red phase to the green phase. As already mentioned, the conventional dimmable light signal system 20 requires an additional dimming transformer 6, which requires more space and is relatively expensive. Furthermore, in Figure 1 a neutral conductor N between the signal transmitter unit 3 and the voltage supply interface 15 is also shown.

In the FIG 2 a conventional light signal system 30 with an alternative voltage supply circuit 1 is shown. In the FIG 2 The traffic signal system 30 shown, like the one in FIG FIG 1 The light signal system 20 shown has a lamp switching device 2 and a signal transmitter unit 3. The voltage supply circuit 1 of the alternative light signal system 30 comprises instead of the in Figure 1 The dimming transformer 6 shown has two voltage converters 13, 14 connected in parallel, which can be designed, for example, as so-called switched-mode power supplies. A first voltage converter 13 converts a supply voltage V _supp of 230 V into a direct voltage of 18 volts and a second voltage converter 14 connected in parallel with the first voltage converter 13 converts the supply voltage V _supp of 230 V into a direct voltage of 24 volts. Between the two voltage converters 13, 14 and the signal line 7, which the voltage supply circuit 1 connects to the lamp switching device 2, a signal voltage changeover switch 8, 9 is connected, which can switch one of the two DC voltages to the signal voltage line 7. If the lower signal voltage V _sig of 18V is applied to the signal generators 3a, 3b, 3c, the brightness of the corresponding signal generator 3a, 3b, 3c is reduced. _{If a signal voltage V sig} of 24V is applied to the signal transmitters 3a, 3b, 3c, the respective activated signal transmitter lights up with full brightness. In addition, in Figure 2 a neutral conductor N between the signal transmitter unit 3 and the voltage supply interface 15 is also shown.

In FIG 3 a light signal system 40 is shown with a circuit arrangement 41 according to an embodiment of the invention. The traffic light system 40 in FIG 3 includes similar to those in the Figures 1 and 2 Light signal systems 20, 30 shown have a voltage supply circuit 41 which is used to provide a supply voltage or signal voltage of a carrier signal SIG that is suitable for a specific brightness of a signal transmitter. In addition, the light signal system 40 comprises a lamp switching device 42 which is used to switch between different signal transmitters of a signal transmitter unit 43. Furthermore, the in FIG 3 The light signal system 40 shown has a signal transmitter unit 43. For example, the signal transmitter unit 43 comprises a signal transmitter 43a for red light, a signal transmitter 43b for yellow light and a signal transmitter 43c for green light. In the FIG 3 The lamp switching device 42 shown has a structure similar to that of the corresponding ones in FIG FIG 1 and FIG 2 units shown, in particular the in FIG 3 The lamp switching device 42 shown also has three lamp switches 10, 11, 12 with which a signal MOD can be switched to one of the signal transmitters 3a, 3b, 3b. Externally, the in FIG 3 The signal transmitter unit 43 shown also has the one shown in FIG FIG 1 and FIG 2 The signal transmitter units shown have a similar structure. However, the in FIG 3 shown signal heads to so-called intelligent signaling devices. These intelligent signal transmitters make it possible to send digital telegrams or states from the controller, ie the circuit arrangement according to the invention, to the signal transmitter by modulating the supply voltage or signal voltage. An intelligent control in the signal transmitter regulates the light output depending on the information content of the digital telegram. Part of an intelligent signal transmitter is also a demodulator (not shown) which analyzes the modulated signal received from the voltage supply circuit in such a way that the information contained relating to the brightness of the signal transmitter can be detected and further processed by the signal transmitter.

The structure of the in FIG 3 The voltage supply circuit 41 shown in accordance with an exemplary embodiment of the invention differs considerably from the conventional ones in FIG FIG 1 and FIG 2 power supply circuits 1 shown.

In the FIG 3 The voltage supply circuit 41 shown comprises a modulation signal generation unit 44 which is set up to generate a modulation signal MD. The modulation signal MD contains control information which is evaluated by the signal generator unit 43 and interpreted as a control command. The modulation signal generation unit 44 is electrically connected to a modulator unit 45. The modulator unit 45 is connected via a switch 8 to a voltage converter unit 14, which converts a supply voltage of 230V into a carrier signal voltage V _sig (see FIG FIG 4 ) from 24 volts DC voltage. If the modulator unit 45 is activated and the switch 8 is switched to pass, a modulation signal MD generated by the modulation signal generation unit 44 is modulated onto the carrier signal SIG. Various methods can be used for modulation, such as frequency modulation or amplitude modulation or square wave modulation (as already written above, all signal forms are possible). In addition, the circuit arrangement 41 has a control data receiving unit 46 for receiving a control signal. In this exemplary embodiment, the control data receiving unit 46 is part of the modulator unit 45. The control signal S includes information relating to a brightness of the light signal system 40 to be set, ie the modulation signal MD is generated as a function of a control signal S.

The modulated signal MOD is then passed on via the lamp switch unit 42 to one of the signal generators 43a, 43b, 43c of the signal generator unit 43. Each of the signal generators 43a, 43b, 43c preferably comprises a signal processor with a demodulator (not shown) which divides the received modulated signal MOD again into the modulation signal MD with the control information and the carrier signal SIG. The signal processor of the respective signal transmitter 43a, 43b, 43c then uses the control commands contained in the control signal S or modulation signal MD to set a current through its lighting unit or a voltage applied to the lighting unit of the signal transmitter 43a, 43b, 43c to the commanded value. In this way, the brightness of the signal transmitters 43a, 43b, 43c can be dimmed in multiple stages or even continuously. In addition, in Figure 3 a neutral conductor N is shown between the signal transmitter unit 43 and the voltage supply interface 15.

In FIG 4 is a circuit arrangement 41 of a light signal system according to an embodiment of the invention with the most important elements, ie the modulation signal generating unit 44, the modulator unit 45 and the switch 8, shown enlarged. The in FIG 4 The embodiment shown, the principle of frequency modulation is used for modulation. The modulation signal generating unit 44 generates a sinusoidal signal which, depending on whether the signal generators (not shown) should light up with full brightness or light up with reduced brightness, a includes different frequency. In the in FIG 4 The specific example shown, the frequency of the modulation signal MD is set to 1 kHz for normal brightness and set to 2 kHz for dimming. The modulation signal MD generated by the modulation signal generation unit 44 is sent to the modulator unit 45 and there modulated onto a carrier signal SIG so that a modulated signal MOD is generated.

The carrier signal SIG is in the FIG 4 at the top left in a diagram as a voltage signal with the direct voltage V _sig , which is constant over time t. Top right in the Figure 4 the modulated signal MOD is also shown as a voltage signal as a function of time. In a first time segment from t = 0, the frequency of the modulated signal MOD is 1 kHz. In other words, a control command is transmitted that the signal generators should light up with full brightness NH. At t = t ₁ , the frequency of the modulated signal MOD is changed to 2 kHz. A control command is now transmitted with the modulated signal MOD that the signal generators should light up with reduced brightness Dim, i.e. should be dimmed.

In FIG 5 a circuit arrangement 41a of a light signal system according to an alternative embodiment of the invention with the most important elements, ie a modulation signal generating unit 44, a modulator unit 45 and a switch 8 is shown enlarged. The in FIG 5 The embodiment shown, the principle of square wave modulation is used for modulation. The modulation signal generation unit 44 generates a square wave signal with a fixed frequency and pulse width. In the event that the signal generators are to shine with full brightness, no signal is output by the modulation signal generation unit 44. In the event that the signal generators are to shine with reduced brightness, a square-wave signal is used as the modulation signal MD by the modulation signal generation unit 44 generated. In the in FIG 5 The specific example shown, the frequency of the rectangular modulation signal MD for dimming is set to 1 kHz. In the case of reduced brightness, the rectangular modulation signal MD generated by the modulation signal generation unit 44 is sent to the modulator unit 45 and there modulated onto a carrier signal SIG so that a modulated signal MOD is generated. The carrier signal SIG is in the Figure 5 at the top left in a diagram as a voltage signal with the voltage V _SIG as a function of the time t. It is designed as a constant DC voltage signal.

Top right in the FIG 5 the modulated signal MOD is also shown as a voltage signal as a function of time. In a first time segment from t = 0, the frequency of the modulated signal MOD is 1 kHz and the signal has a rectangular modulation of the amplitude. In other words, a control command is transmitted that the signal generators should light up with reduced brightness Dim. At t = t ₁ , the modulated signal MOD is changed in such a way that only the constant carrier signal SIG is now transmitted. A control command is now transmitted with the modulated signal MOD that the signal generators should light up with full brightness NH. The square-wave modulation by the modulator 45 in the exemplary embodiment in FIG FIG 5 corresponds to an addition of the modulation signal MD to the carrier signal SIG. In other words, a square-wave signal MD alternating between a positive and a negative value is added to a constant carrier signal SIG.

In FIG 6 a circuit arrangement 41b of a light signal system according to a further alternative embodiment of the invention with the most important elements, ie a modulation signal generating unit 44 and a switch 8 is shown enlarged. The in FIG 6 The embodiment shown is the same as in the in FIG 5 Shown embodiment for modulation the principle of square modulation used. The arrangement in FIG 6 however, is simplified in that the in FIG 5 The modulator unit 45 shown is omitted and only one switch 8 is formed instead. The switch 8 provides a switchable electrical connection between the voltage converter unit 14 (see FIG FIG 3 ) and the line 7 to the lamp switch unit 42. The control of the switch 8 takes place in the in FIG 6 shown embodiment by the modulation signal generation unit 44. The modulation signal generation unit 44 in turn generates a square-wave signal with a fixed frequency and pulse width. In the event that the signal generators are to shine with full brightness, no signal is output by the modulation signal generation unit 44. The switch 8 thus remains switched on and the constant carrier signal SIG is output as the control signal MOD. In the event that the signal generators are to light up with a reduced brightness, also referred to as dimming or dimming status, a square-wave signal is output by the modulation signal generating unit 44. The switch 8 is now controlled with the square-wave signal, which causes the switch to change between the open state and the open state. If the switch 8 is on, the modulated signal MOD has an amplitude corresponding to the amplitude of the carrier signal SIG. If the switch 8 is open, however, there is no signal on the line to the voltage converter unit 14 and the amplitude of the modulated signal MOD is 0. In the in FIG 6 The specific example shown, the frequency of the rectangular modulation signal MD for dimming is set to 1 kHz. The carrier signal SIG is in the FIG 6 at the top left in a diagram as a voltage signal with the voltage V as a function of the time t. It is designed as a constant DC voltage signal. Top right in the FIG 6 the modulated signal MOD is also shown as a voltage signal as a function of time. In a first time segment from t = 0, the frequency of the modulated signal MOD is 1 kHz and the signal has a rectangular shape. That is, a control command is transmitted, that the signal heads should light up with reduced brightness Dim. At t = t ₁ , the modulated signal MOD is changed in such a way that only the constant carrier signal SIG is now transmitted, that is to say, the switch 8 is now permanently switched through. In this state, a control command is transmitted with the modulated signal MOD that the signal transmitter should light up with full brightness NH.

In FIG 7 a circuit arrangement 41c of a light signal system according to a further alternative embodiment of the invention with the most important elements, ie a modulation signal generating unit 44, a switch 8 and an amplitude swing setting unit 47 is shown enlarged. The in FIG 7 The embodiment shown is the same as in the in FIG 6 The embodiment shown uses the principle of square wave modulation for modulation. The arrangement in FIG 7 is just like the in FIG 6 The arrangement shown is designed in such a way that the modulation of the carrier signal SIG is implemented by controlling the switch 8. The switch 8 provides a switchable electrical connection between the voltage converter unit 14 (see FIG FIG 3 ) and the line 7 to the lamp switch unit 42. The switch 8 is controlled by a modulation signal MD generated by the modulation signal generation unit 44. In this respect, the structure corresponds to that in FIG 7 The circuit arrangement 41c shown corresponds to the structure in FIG FIG 6 . In addition, however, the circuit arrangement 41c also includes an amplitude deviation setting unit 47. The amplitude deviation setting unit can, for example, have a diode path or be designed as a series regulator. It bridges the switch 8 or is connected in parallel to it. The amplitude swing setting unit 47 functions to the effect that, depending on the set resistance of the amplitude swing setting unit 47, a corresponding voltage .DELTA.U drops across the switch 8 across the bridge formed by the amplitude swing setting unit 47. If the switch 8 is switched on, no voltage drops across the switch 8, since the switch 8 has a minimal resistance in the on state Has. However, if the switch 8 is open, ie blocked, the carrier signal SIG is not completely interrupted, but can continue to be reduced via the bridge formed by the amplitude swing setting unit 47 by the voltage .DELTA.U falling across the bridge or the amplitude swing setting unit 47 are present at the output of the circuit arrangement 41c.

As in the embodiment in FIG 6 the modulation signal generation unit 44 in turn generates a square-wave signal with a fixed frequency and pulse width. In the event that the signal generators are to shine with full brightness, no signal is output by the modulation signal generation unit 44. The switch 8 thus remains switched on and the constant carrier signal SIG is output as the control signal MOD. In the event that the signal generators are to light up with a reduced brightness, also referred to as dimming or dimming status, a square-wave signal is output by the modulation signal generating unit 44. The switch 8 is now controlled with the square-wave signal, which causes the switch 8 to change between the open state and the open state. If the switch 8 is on, the modulated signal MOD has an amplitude corresponding to the amplitude of the carrier signal SIG. If the switch 8 is open, however, a signal reduced by the voltage ΔU is present on the line 7 to the lamp switch unit 42 and the amplitude of the modulated signal MOD is V _sig - ΔU. In the in FIG 7 The specific example shown, the frequency of the rectangular modulation signal MD for dimming is set to 1 kHz. The carrier signal SIG is in the FIG 7 at the top left in a diagram as a voltage signal with the voltage V as a function of the time t. It is designed as a constant DC voltage signal. Top right in the FIG 7 the modulated signal MOD is also shown as a voltage signal as a function of time. In a first time segment from t = 0, the frequency of the modulated signal MOD is 1 kHz and the modulated signal MOD has a rectangular shape, the minimum amplitude of the electrical voltage of the modulated signal MOD being V _sig − ΔU and the maximum amplitude being V _sig . In other words, a control command is transmitted that the signal generators should light up with reduced brightness Dim. At t = t ₁ , the modulated signal MOD is changed in such a way that only the constant carrier signal SIG is now transmitted, that is to say the switch 8 is now permanently switched through. A control command is now transmitted with the modulated signal MOD or the carrier signal SIG that the signal generators should light up with full brightness NH. By setting the modulation swing, the interference immunity and the efficiency of the circuit arrangement can be influenced. If a large amplitude swing .DELTA.U is selected, then the interference immunity increases or an improved signal / noise ratio is achieved. However, the efficiency of the circuit decreases in connection with this measure. If, on the other hand, a lower amplitude swing ΔU is selected, the efficiency is improved, but in this case a lower immunity to interference is accepted.

In FIG 8 a circuit arrangement 41d of a light signal system according to a further alternative embodiment of the invention with the most important elements, ie a modulation signal generating unit 44, a clock control unit 48, a mixer unit 49, a switch 8 and an amplitude deviation setting unit 47, is shown enlarged. The in FIG 8 The embodiment shown is the same as in the in FIG 7 The embodiment shown uses the principle of square wave modulation for modulation. The arrangement in FIG 8 is just like the in FIG 7 The arrangement shown is designed in such a way that the modulation of the carrier signal SIG is implemented by controlling the switch 8. The switch 8 provides a switchable electrical connection between the voltage converter unit 14 (see FIG FIG 3 ) and the line 7 to the lamp switch unit 42 (see FIG 3 ). Furthermore, the in FIG 8 Circuit arrangement shown 41d as well as the in FIG 7 The circuit arrangement 41c shown has an amplitude swing setting unit 47. The amplitude swing setting unit 47 can be designed, for example, as a diode path or as a series regulator. It bridges the switch 8 or is connected in parallel to it. The function of the amplitude swing adjustment unit 47 is already described in the description of FIG FIG 7 explained so that reference is made to it at this point. The control of the switch 8 takes place in the same way as in the embodiment of FIG FIG 7 with the aid of a modulation signal MD.

In contrast to the in FIG 7 The arrangement 41c shown in FIG FIG 8 however, the modulation signal MD is generated by mixing, such as, for example, multiplying, the signal MD generated by the modulation signal generation unit 44 with a clock control signal TKT, which is generated by the clock control unit 48. The two signals MD, TKT are mixed in a mixer unit 49, that is to say multiplied, for example, which results in a mixed modulation signal MMD with which the switch 8 is controlled.

The clock control unit 48 specifies the pulse duty factor between the system time t _sys and a modulation time t _mod in the event of a reduction in the brightness of the signal generator. The clock signal TKT corresponding to the duty cycle is shown at the bottom left in a diagram in FIG FIG 8 shown. The clock signal TKT is generated as a square-wave signal with the modulation time t _mod at time intervals t _sys . As in the embodiment in FIG 7 the modulation signal generation unit 44 in turn generates a square-wave signal MD with a fixed frequency and pulse width. This signal is on the left FIG 8 shown above the diagram for the clock signal. In the event that the signal generators are to shine with full brightness, no signal is output by the modulation signal generation unit 44. The switch 8 thus remains switched on and the constant carrier signal SIG is output as the control signal MOD. In the event that the signal transmitters are to light up with reduced brightness, also referred to as dimming or dimming status, a square-wave signal MD is output by the modulation signal generating unit 44. The square-wave signal MD is mixed in the mixer unit 49 with the clock control signal TKT from the clock control unit 48, a mixed modulation signal MMD being generated. The switch 8 is now controlled with the mixed modulation signal MMD, which has the effect that the switch 8 changes between the open state and the open state _{only during the modulation time t mod.} If the switch 8 is on, the modulated signal MOD has an amplitude corresponding to the amplitude of the carrier signal SIG. If the switch 8 is open, however, a signal reduced by the voltage ΔU is present on the line to the lamp switch unit 42 (see FIG FIG 3 ) and the amplitude of the modulated signal MOD is V _sig -ΔU.

In the in FIG 8 The specific example shown, the frequency of the rectangular modulation signal MD for dimming is set to 1 kHz. The carrier signal SIG is in the FIG 8 at the top left in a diagram as a voltage signal with the voltage V as a function of the time t. It is designed as a constant DC voltage signal. Top right in the FIG 8 the modulated signal MOD is also shown as a voltage signal as a function of time. In a first time segment from t = 0 to t = t _mod , the frequency of the modulated signal MOD is 1 kHz and the modulated signal MOD has a rectangular shape, the minimum amplitude of the modulated signal MOD being V _sig -ΔU and the maximum Amplitude V _sig . In other words, a control command is transmitted that the signal generators should light up with reduced brightness Dim. At t = t _mod , based on the modulation time t _mod determined by the clock control unit, the modulated signal MOD is changed to the effect that only the constant carrier signal SIG is now transmitted, ie the switch 8 is now permanently switched through. Due to the established System time t _sys, which is greater than the modulation time t _mod, but is of the driven signal transmitter at the time t _mod no change of brightness made, since the processor of the signal generator with the system time t _sys is clocked and thus only the time _sys t a awaiting new command from lamp switch unit 41d. From the point in time t ₁ = t _sys , a control command is transmitted with the modulated signal MOD, which corresponds to the constant carrier signal SIG at this point in time, that the signal transmitters should light up with full brightness NH. If the signal generator detects _{a dimming command at the beginning of t sys} due to the modulation, the signal generator is controlled dimmed _{until the end of t sys.} The evaluation is repeated in the next time slot. The advantage of clock-controlled modulation is that the power loss can be limited and thus the efficiency of the circuit arrangement 41d can be favorably influenced.

wobei I_sig die dem ummodulierten Trägersignal SIG entsprechende Stromstärke ist, ΔU der Amplitudenhub ist, t_sys der Systemtakt ist, mit dem die Signalgeber Signale empfangen, und t_mod die bereits erwähnte Modulationszeit ist.The power loss P _{v of} the circuit arrangement 41d results from $${\mathrm{P.}}_{\mathrm{v}}={\mathrm{I.}}_{\mathrm{sig}}\cdot \mathrm{\Delta }\mathrm{U}\cdot {\mathrm{t}}_{\mathrm{sys}}\cdot {\mathrm{t}}_{\mathrm{mod}},$$

where I _{sig is} the current strength corresponding to the modulated carrier signal SIG, ΔU is the amplitude swing, t _{sys is} the system clock with which the signal generators receive signals, and t _{mod is} the aforementioned modulation time.

wobei U₀ = V_SIG, d.h. die Spannung des Trägersignals SIG ist.The efficiency η results from $$\mathrm{\eta }=\frac{{\mathrm{U}}_0-\mathrm{\Delta }\mathrm{U}\cdot {\mathrm{t}}_{\mathrm{sys}}\cdot {\mathrm{<figure-callout\; id="0"\; label="t\; mod\; U"\; filenames="imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{mod}}}{{\mathrm{U}}_{}},$$

where U ₀ = V _SIG , ie the voltage of the carrier signal SIG.

In FIG 9 is a diagram to illustrate the relationship between the modulated control signal MOD, which in the diagram in the upper area as a function of the _{Time is shown, and the current I v} flowing through the lighting units of the signal generators is shown. A circuit arrangement 41d according to the one in FIG FIG 8 embodiment shown. The time t (on the abscissa) is divided into time slots TS = 1 to TS = 8. In this case, the length of the time slots corresponds to the system time t _sys . When TS = 1, the system is switched on and a dimming command is transmitted to a signal transmitter with the aid of a modulated control signal MOD. The signal generator regulates the current I _V through the lighting unit, for example an LED, down, so that energy can be saved and a dazzling effect of the traffic is avoided. With the time slots TS = 2 and TS = 3, a new dimming command is received from the signal transmitter at the beginning of the time slot and the dimming, ie the lighting with reduced brightness, is continued. With TS = 4, no control signal at all is passed on to the signal generators, so that the signal generators do not light up. (This is done in the lamp switch using switches 10, 11 and 12. With the time slot TS = 6, the supply voltage is switched on again, but the carrier signal SIG is not modulated in this case, which is interpreted by the signal transmitter as a command to illuminate with full brightness so that the current I _V through the lighting units is maximum.

In FIG 10 a method 100 for setting the brightness of a traffic signal system 40 according to an exemplary embodiment of the invention is illustrated in a flowchart. In step 10.I, a control signal S is received, which includes information relating to a brightness of the light signal system 40 to be set. The control signal S can come from an external device, such as a traffic control center, for example. According to step 10.II, a carrier signal SIG also becomes continuous over time by converting an electrical supply voltage V _{supp present} at the voltage supply interface into an electrical one Carrier signal voltage V _sig generated. The carrier signal SIG is used to transport the control information to a signal transmitter 43 of the light signal system 40. In step 10. III, a modulation signal MD is generated as a function of the received control signal S. In step 10.IV, the carrier signal SIG for the signal generator 43 is modulated with the modulation signal MD to form a modulated control signal MOD.

Finally, it is pointed out once again that the devices and methods described above are merely preferred exemplary embodiments of the invention. For the sake of completeness, it is also pointed out that the use of the indefinite article “a” or “an” does not exclude the possibility of the relevant features also being present several times. Likewise, the term “unit” does not exclude the possibility that it consists of several components which, if necessary, can also be spatially distributed.

Claims (12)

1. Light signal system (40) having:

   - a circuit arrangement (41, 41a, 41b, 41c, 41d) for adjusting the brightness of signal transmitters (43a, 43b, 43c) of the light signal system (40), the circuit arrangement (41, 41a, 41b, 41c, 41d) having:

   - a voltage supply interface (15) for receiving an electrical supply voltage (V_supp),

   the light signal system further having:

   - a signal transmitter device (43), having the signal transmitters (43a, 43b, 43c), and

   - a signal transmitter switching unit (42) which is connected between the circuit arrangement (41, 41a, 41b, 41c, 41d) and the signal transmitter device (43) and is configured to switch over between different signal transmitters (43a, 43b, 43c) and to electrically connect the different signal transmitters (43a, 43b, 43c) to the circuit arrangement (41, 41a, 41b, 41c, 41d) or to electrically disconnect the different signal transmitters (43a, 43b, 43c) from the circuit arrangement (41, 41a, 41b, 41c, 41d),

   characterised in that

   - the circuit arrangement (41, 41a, 41b, 41c, 41d) further has:

   - a voltage conversion unit (14) for generating a carrier signal (SIG) as a direct current voltage signal by converting the electrical supply voltage (V_supp) into a carrier signal voltage (V_sig),

   - a control data receive unit (46) for receiving a control signal (S), wherein the control signal (S) comprises control commands in respect of a brightness that is to be set for the light signal system (40),

   - a modulation signal generation unit (44) for generating a modulation signal (MD) as a function of the received control signal (S), and

   - a modulator unit (45, 8) for modulating the carrier signal (SIG) by means of the modulation signal (MD) into a modulated control signal (MOD) for controlling the brightness of the signal transmitters (43a, 43b, 43c),

   - wherein each signal transmitter (43a, 43b, 43c) has:

   - a demodulation unit which is configured to receive the modulated control signal (MOD) from the circuit arrangement (41) and to demodulate the same into the modulation signal (MD) and the carrier signal (SIG), and

   - a signal processor which is configured to set, on the basis of the control commands contained in the modulation signal (MD), a current flowing through the signal transmitter or an electrical voltage present at the signal transmitter to a command-specified value.
2. Light signal system (40) according to claim 1, further having an additional switch (8) between the voltage conversion unit and the modulator unit (45).
3. Light signal system (40) according to claim 1 or 2, wherein the modulation signal generation unit (44) is configured to generate a sinusoidal signal as the modulation signal (MD).
4. Light signal system (40) according to claim 3, wherein the sinusoidal signal has a frequency of 1 kHz for setting a normal brightness and a frequency of 2 kHz for a weaker brightness.
5. Light signal system (40) according to one of claims 1 or 2, wherein the modulation signal generation unit (44) is configured to generate a square-wave signal as the modulation signal (MD).
6. Light signal system (40) according to claim 5, wherein the modulator unit (45) is actuated in such a way that no square-wave signal is modulated in order to set a normal brightness, and for a weaker brightness the carrier signal (SIG) is modulated by means of the square-wave signal having a frequency of 1 kHz.
7. Light signal system (40) according to one of claims 1, 2 or 5 to 6, having an amplitude swing setting unit (47) which is configured to set an amplitude of the modulated control signal (MOD) .
8. Light signal system (40) according to claim 7, wherein the amplitude swing setting unit (47) has a diode path or a linear regulator which bypasses the modulator unit (45).
9. Light signal system (40) according to one of claims 7 or 8, having a clock control unit (48) which is configured to specify a duty cycle with which the carrier signal (SIG) is modulated by means of the modulation signal (MD).
10. Light signal system (40) according to claim 9, having a signal multiplication unit (49) which is configured to multiply a clock signal (TKT) generated by the clock control unit (48) with the modulation signal (MD).
11. Method (100) for adjusting the brightness of signal transmitters (43a, 43b, 43c) of a light signal system (40), the light signal system (40) having a circuit arrangement (41, 41a, 41b, 41c, 41d), a signal transmitter device (43) and a signal transmitter switching unit (42), the circuit arrangement (41, 41a, 41b, 41c, 41d) having a voltage supply interface (15), a voltage conversion unit (14), a control data receive unit (46), a modulation signal generation unit (44) and a modulator unit (45, 8), the signal transmitter device having the signal transmitters (43a, 43b, 43c), and each signal transmitter (43a, 43b, 43c) having a demodulation unit and a signal processor, the method having the steps:

    - receiving a control signal (S) by way of the control data receive unit (46), wherein the control signal (S) comprises control commands in respect of a brightness that is to be set for the light signal system (40),

    - generating a carrier signal (SIG) as a direct current voltage signal by converting a supply voltage (V_supp) into a carrier signal voltage (V_sig) by way of voltage conversion unit (14),

    - generating a modulation signal (MD) as a function of the received control signal (S) by way of the modulation signal generation unit (44),

    - modulating, by way of the modulator unit (45, 8), the carrier signal (SIG) by means of the modulation signal (MD) into a modulated control signal (MOD) for controlling the brightness of the light signal system (40),

    - switching over to a selected signal transmitter (43a, 43b, 43c) by way of the signal transmitter switching unit (42),

    - receiving, by way of the demodulation unit of the selected signal transmitter (43a, 43b, 43c), the modulated control signal (MOD) from the circuit arrangement (41),

    - demodulating, by way of the signal processor of the selected signal transmitter (43a, 43b, 43c), the control signal (MOD) into the modulation signal (MD) and the carrier signal (SIG),

    - determining, by way of the signal processor of the selected signal transmitter (43a, 43b, 43c), the control signal on the basis of the modulation signal (MD),

    - setting a current flowing through the signal processor of the selected signal transmitter (43a, 43b, 43c) or an electrical voltage present at the selected signal transmitter (43a, 43b, 43c) to a command-specified value on the basis of the control commands contained in the modulation signal (MD).
12. Computer program product which is loadable directly into a memory of a light signal system (40) according to one of claims 1 to 10 and has program code sections for carrying out all steps of the method according to claim 11 when the program is executed in the light signal system (40).

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