NO300750B1 - Brightness control system and operating conditions for gas discharge lamps - Google Patents

Abstract

A variable frequency inverter (30) supplies a load circuit (40), incorporating two fluorescent lamps (LA1, LA2). An integrated control circuit (17) includes a transceiver (10), to which commands are addressed for adjustment of the brightness and operational mode. With the lamps switched off, the inverter (30) is switched by a driver circuit (31) into SLEEP mode either immediately or after a preset delay, to be reactivated by reception of a fresh brightness command. It is fed from the mains via an on/off switch (S1) and a rectifier (20).

Description

The invention generally relates to a system for controlling the brightness and operating conditions of fluorescent lamps.

Modern electronic drive circuits serve to control fluorescent lamps. Thereby, the fluorescent lamps can be adjusted to a more gentle operation and the efficiency of such lamp types can also be improved. At the same time, an electronic drive circuit usually exhibits the following features: A supply voltage, which can be a direct voltage or an alternating voltage, is supplied to a rectifier and an intermediate circuit capacitor via a mains input filter. If the device is operated exclusively with direct voltage, the last rectifier may be omitted. A high intermediate circuit voltage U0 is formed on the intermediate circuit capacitor, which with a normal mains voltage supply of 220 V is in the order of approx. 300 V. An alternating voltage generator formed by a half-bridge or full-bridge inverter is connected to the intermediate circuit. It provides a frequency-variable output voltage on an output load circuit, which, if a half-bridge connection with artificial voltage determination (Spannungsmittelabgriff) is not provided, exhibits a series resonant circuit. In line with the series resonant circuit is the discharge line of the gas discharge lamp or fluorescent lamp to be controlled.

The output frequency of the inverter is in the range of around 10 kHz - 50 kHz.

At the mentioned frequencies, the efficiency of the connected fluorescent lamps is increased in relation to operation with the 50 Hz supply network. Increased light output is achieved with the same electrical input power. Because of the high frequency, the inductance of the inverter on the output side of the series resonant circuit can be kept low. Finally, the variable frequency control allows brightness regulation of the fluorescent lamp which - on a normal network - is very difficult to regulate (dimming). Finally, with the frequency control, lighting of the fluorescent lamp can also be prepared and initiated.

The aforementioned ignition sequence also includes a so-called warm start to protect the fluorescent lamp, whereby the heating wires of the fluorescent lamp are preheated before, due to resonant behaviour, a high ignition voltage is applied to the lamp which leads to ignition and thereby operation of the gas discharge lamp. Variation in the frequency that controls the ignition also allows, during operation of the gas discharge lamp, an almost stepless brightness regulation within wide limits by frequency shift. Such a stepless and continuous control of the brightness requires special precautions due to the negative internal resistance in the fluorescent lamps that are in operation .

An important purpose for the development of a modern electronic drive circuit is therefore, firstly, the most versatile control option possible, especially a brightness control. This with a view to the operating conditions as well as the brightness regulation for the fluorescent lamps which are connected to the drive circuit in question.

In addition to versatile control and regulation, another purpose of modern drive circuits is that they should provide comfortable handling and operation of many decentralized light sources. This is particularly the case for large projects where extensive lighting systems with a large number of light sources are to be installed.

From EP-A-244777 a control circuit for gas discharge lamps is known, which contains a receiver device for receiving binary control signals. The received binary control signals are passed on in converted form to a control device which, depending on these control signals, sets the frequency of the inverter analogically, and thus also the brightness of the gas discharge lamp. According to this publication, the control signals serve exclusively to control brightness.

The publication IEEE Transactions on Applications and Industry, Volume 1A-20, No. 5, September 1984, pp. 1198-1205, New York, "The Integration of microcomputers and controllable output ballasts" discloses a system for controlling the brightness of multiple lamps. The lamps are controlled by electronic drive circuits, which in turn are connected to a central control unit. Actual values for the lamps' brightness are read by photo sensors, and sent to the central control unit. The photo sensors are arranged separately from the electronic drive circuits. The brightness of the connected gas discharge lamps is controlled analogously using pulse width modulation.

It is an essential purpose of the present invention to provide increased safety for the connected fluorescent lamps, as well as improved monitoring possibilities for these. Safety, not least, also for the operating staff who have to replace lamps that have fallen out, and thereby depend on the voltages that arise when replacing lamps in the sockets and in the device being harmless. This is important for the reason that with many lighting systems, the individual lamps cannot be individually turned off, so that it is necessary to replace lamps while the system is in operation.

According to the invention, the aforementioned problems are solved by means of a system for monitoring and remote control of one or more electronic drive circuits for gas discharge lamps from a central control device, where each drive circuit comprises a rectifier circuit that can be connected to the alternating current network

(the web),

an alternating voltage generator that is fed from

the rectifier circuit and has variable output frequency,

a load circuit containing at least one series swing circuit and at least one gas discharge lamp and which is fed from the alternating voltage generator with its variable output frequency,

as well as the central control apparatus.

The system is characterized by

(a) the central control apparatus

is connected to each electronic drive circuit via respective bus wire pairs or via a single, common

bus s wire pair,

contains means for providing digital control signals for the operating state, such as emergency, sleep, ignition, off or on state and the lamp brightness and/or lamp power for each electronic drive circuit, as well as for transmitting these control signals to the corresponding

bus wire pairs, and

contains means for receiving and for evaluating digital error messages and/or digital operational status

information transmitted from each electronic drive circuit to

the corresponding bus line, and that

(b) each electronic drive circuit also comprises a digital interface designed as a transmitter and receiver device and connected to the corresponding bus wire pair to receive the digital control signals emitted from the central control apparatus and to issue digital error messages and/or digital operating state information to the central control apparatus, and

a control device connected to the digital interface, which control device evaluates the digital control signals transmitted to it from the digital interface to control or regulate the electronic drive circuit, and which control device evaluates measured value signals, which are recorded from the electronic drive circuit, and produces digital error messages and operating state information from these and transfers this to the digital interface.

In addition, the control device can also act as a regulation device for the electronic drive circuit or each electronic drive circuit, as it evaluates the measured value signals from this as actual value quantities and evaluates the indirect and centrally supplied control signals via the digital interface and/or the directly and centrally supplied control signals as nominal value quantities, and in accordance with this provides digital control signals for regulating the output frequency of the alternating voltage generator.

It is advantageous for a pair of fluorescent lamps on an alternating voltage generator to be driven by a relevant non-central electronic drive circuit. This gives a so-called two-lamp drive circuit.

In addition to comfortable brightness regulation, the control and regulation device allows a targeted increase in the lifetime of the fluorescent lamps and a guarantee for safety interests. With the aid of the aforementioned control and regulation device, the operating condition and the current operating state of a drive circuit-fed fluorescent lamp can be precisely controlled and monitored. Thus, the warm start, ignition, dimming and switch-off sequence (ON, DIM, OUT, IN) takes place one after the other with high precision and in a lamp-friendly way. Inadmissible operating conditions are avoided, and before an actual ignition, extensive preheating of the heating wires is ensured. In addition to brightness-regulated dimming operation (DIM), the entire drive circuit can be put inactive (SLEEP) when no brightness is desired for a long time. In this state the drive circuit takes up only a minimal load and losses are avoided.

Alongside regular dimming mode, where the brightness of the fluorescent lamps is variable (DIM) between a minimum value (MIN) and a maximum value (MAX), it is also possible with an emergency mode (EMERGENCY), where the lamp takes on an emergency lighting light level. This can be predetermined decentralized for the device in question. In certain dangerous conditions, it is automatically activated.

The transmitting and recording device is connected to the central control device via a bidirectional bus line. Such a control device makes it possible to remotely control a number of non-centrally arranged electronic drive circuits from a central location. In addition to the remote control, the control device also provides operating status information. In the lighting system, on the basis of error messages, occurring errors are detected and acknowledged, which are sent by the non-central drive circuits via the two-way bus line to the central control device. Maintenance work is thereby simplified and accelerated. Multiple monitoring functions such as over- and under-voltage monitoring are precisely arranged decentralized (patent claim 6). With the help of these monitoring functions, the lifetime of the fluorescent lamps is noticeably increased.

The brightness regulation of the non-central electronic drive circuits controlled via the bus line takes place via serial digital control words that indicate control commands or brightness data information (patent claim 13). Particularly advantageous is the organization in functional groups where a majority of driving circuits such as e.g. are arranged in a room, are controllable simultaneously and with a single command.

The connection of the sending and receiving device to the bus line is advantageously provided by means of a differentiating link. This ensures a strong attenuation of the 50 Hz mains frequency and works with very small input currents. The damping of the mains frequency goes so far that pole protection (Verpolungsschutz) is also ensured, and applying 220 V to the bus line does not result in damage (patent claim 15).

When the fluorescent lamps are controlled to dimming mode after ignition, light pulses of short duration may occur. These have their cause in the energy that is stored in the output circuit during the ignition sequence and which then appears as an unwanted light pulse in dimming mode. This can be remedied by extending the - which actually shortens the service life - glow phase between ignition and stationary operation (patent claim 19). However, an actual lifetime shortening is avoided by only extending the glimmer area by a small brightness value. The greater the brightness, the shorter the glow phase and the faster the transition from ignition operation to normal operation (patent claim 20).

If the control and regulation device according to the invention is supplied with a series of m measured values from the electronic drive circuit, one can recognize a series of operating states, respectively dangerous states and avoid them, based on these. Furthermore, it becomes possible with a real power regulation that works independently of the lamp type (e.g. argon lamps or krypton lamps). It is advantageous if the lamp brightness regulation is achieved by means of a frequency modulation or by a combination of frequency modulation and duty cycle change (patent claim 12).

When it comes to the monitoring aspect, the control of the heating wire current to the fluorescent lamp also comes into play. This gives an accurate message as to whether certain lamps are defective or not switched on at all (patent claim 27).

The "running layers" which occur in strong dimming operation are advantageously avoided when a small direct current component is superimposed on the high-frequency lamp alternating current (patent claim 29).

If a pair of fluorescent lamps are inserted for each drive circuit, and the fluorescent lamps are fed from a common alternating voltage generator, the inductive symmetry element according to the invention causes a symmetrical operation for both fluorescent lamps (patent claim 32). A voltage-controlled wire heating makes it possible with lamp-individual heating transformers which, with their primary winding, are connected to the alternating voltage output circuit (patent claim 36). Via a primary current recording rig, the control and regulation device can at any time draw conclusions about the heating wire condition and thereby identify already damaged fluorescent lamps or fluorescent lamps that will soon fail (patent claim 37).

Further advantageous aspects and embodiments of the system according to the invention are described in more detail in the sub-claims. With reference to the drawings, embodiments of the invention will be described in more detail below. The drawings show the following: Fig. 1 is a block diagram of an electronic drive circuit according to the invention, Fig. 2 is a block diagram of the system tank according to the invention, where several non-central drive circuits are connected via a bus line 12 to a central control device. Fig. 3 is a block diagram of an exemplary embodiment of the control and regulation device according to the invention as integrated circuit 17, Fig. 4 shows the principle of an input circuit 20 with two measurement value registrations, Fig. 5 is an exemplary embodiment of the transformer-coupled wire heating for a fluorescent lamp with three measuring sensors, Fig. 6 is an embodiment of an output circuit 40 according to the invention, with symmetry element TRI for two fluorescent lamps, Fig. 7 is the principle core for the alternating voltage generator with control drive circuit 31, Fig. 8a-c shows a block diagram of sending and the receiving device 10 with different designs of the connection circuit to the bus line 12, Fig. 9 is a brightness-time diagram to explain

the disconnection and emergency lighting operation,

Fig. 10 is a brightness-time diagram to explain respectively the soft start and soft stop functions of a system design according to Fig. 2. Fig. 1 first shows a block diagram of an embodiment example of an electronic drive circuit according to the invention. The mains voltage UN is supplied to an input circuit 20 (rectifier circuit) - possibly via a switch Sl. This circuit produces the intermediate circuit voltage U0,Udc which is supplied to the alternating voltage generator 30 (inverter). The alternating voltage generator 3 0 emits its high-frequency output voltage UHF on an output load circuit 4 0 which contains one or more fluorescent lamps LA1, LA2. From both the alternating voltage generator 30 and the load circuit 40, a number of system measurement values (process quantities) can be taken. The measured values are taken together to a control and regulation circuit 17 which in turn produces the digital control signals for the inverter 30. These are shifted in potential across a drive circuit 31 and supplied to the inverter's output MOS-FETs. The control and regulation device 17 is also assigned to a sending and receiving device 10 which is connected via a bus line 12 to other drive circuits and/or to a central control device 50.

The latter is shown in Fig.2. There, a number of electronic drive circuits 60-1, 60-2, 60-3, ... 60-i are connected to a common bus line 12. All drive circuits are connected to the central control device 50 via this bus line, to which control device it is assigned a indicator 51. Over the bus line 12 it is now possible to control some or more of the aforementioned drive circuits and to transmit commands to them such as e.g. switching off, switching on, switching on etc. Brightness values can also be pre-set and, conversely, error information can be scanned from the individual devices. In this way, the control device 50 is informed at all times of the complete system state, so that a high degree of operational reliability can be guaranteed, and rapid operation or maintenance of the non-central drive circuits, respectively of their

fluorescent lamps, becomes possible.

The function blocks 20, 30, 40, 10, 17 shown in Fig. 1 will now be explained in more detail with reference to the figures.

Fig. 3 shows the control and regulation device 17 as an integrated circuit. This is supplied with the many m measurement values that express the process signals in Fig. 1. It emits two digital control signals for the end-stage transistor unit to the inverter 30, which via a drive circuit 31 is further amplified and potential shifted.

In addition to the m measurement values, the control and regulation device 17 is also supplied with n nominal or fixed values. These affect the adjustable control and regulation method. Furthermore, a sending and receiving device 10 is arranged which can be part of the control and regulation circuit 17 or separate from it, which sending and receiving device is connected either directly or via a connection circuit to the bus line 12. This forms the serial interface which makes it possible for the control and regulation device to communicate errors and operating state information to the central control device 50.

The n nominal or fixed values mentioned above can also be supplied to this sending and receiving device 10, which after suitable processing sends the signals on to the control and regulation circuit 17. The nominal or fixed values can be, for example, the emergency lighting level (EMERGENCY), the minimum brightness level (MIN ) and the maximum brightness level (MAX). Within the latter two levels, the operation of the adjustable brightness level (DIM) can move.

Serial digital data words with a length of 8 bits are used as command and data words as well as error information words. Other value lengths are possible. Each non-central electronic drive circuit is assigned an address which makes it possible to communicate with separate drive circuits via the address of the sending and receiving device 10 in order to search for information from them or transmit commands. The two-way working method of the bus line 12 enables a problem-free and reasonable connection between a number of non-central drive circuits and a central

control device (50).

Fig. 4 shows a principle core for an input circuit as it can be used to feed the alternating voltage generator 30 from a supply network with voltage UN. The input circuit consists of capacitive input filters and possibly a harmonic choke. The capacitors arranged in the Y circuit serve "for spark or radio noise suppression. In parallel with these, a surge arrester or a VDR is connected. A full-wave rectifier is connected, but this can be removed if the device is operated with direct voltage. After the rectifier, an intermediate circuit capacitor C4 which, at 220 V mains voltage, charges up to approx. 300 V with a ripple or residual pulsation of approx. 10%.

Because the amplitude factor must be kept low, the intermediate circuit voltage U0 must be well smoothed.

Parallel to the intermediate circuit capacitor C4 is a voltage divider R18, R28 on which a measurement signal proportional to the intermediate circuit voltage can be taken. On a low-pass R21, C25, a signal proportional to the supply voltage is recorded, and likewise how the intermediate circuit voltage-dependent measurement signal is supplied to the control and regulation device 17. Both measurement signals serve for supply voltage monitoring and thereby the operational reliability of the electronic drive circuit.

Fig. 5 shows an exemplary embodiment of a load circuit 40 according to the invention with a heating transformer L5 for the pre-heating of the heating wires of the fluorescent lamp LAI. In Fig. 5, only one of a pair of lamp circuits is shown. The embodiment according to the invention exhibits a pair of these branches, i.e. two fluorescent lamps LA1,LA2 on an alternating voltage generator output which emits the high-frequency alternating voltage UHF between the series-connected power switching transistors V21 and V28. The AC voltage generator is fed with an intermediate circuit voltage Udc from the input circuit 20 in Fig. 4. As the fluorescent lamps in operation have a negative internal resistance, they must be fed with high voltage spikes during the ignition sequence (TENN) and when heating the threads with a corresponding heating effect. From the output connection to the inverter 30, a series resonant circuit L2,C15 is passed over a symmetry element TRI, which will be described in more detail later, on the discharge path H2,H4 to the fluorescent lamp. Furthermore, a measuring resistor 32 is arranged in series with the fluorescent tube, on which a voltage is emitted that is proportional to the lamp current IL1, and which is supplied to the control and regulation circuit 17. Between the coil L2 and the capacitor C15, an ignition capacitor C17 is connected to ground ( With the help of this device, the dimming detection line of the discharge lamp can be measured and compared, as the resistance of the capacitor C15 will decrease with increasing frequency and the resistance of the discharge lamp will increase. In parallel with the ignition capacitor C17 is also the primary winding of the heating transformer L5, and further in series with this is a Zener diode V15 and a measuring resistor RIO. On the latter, a voltage proportional to the heating wire current IW1 is taken out and this voltage is supplied to the control and regulation circuit 17 as a further system variable. As the inverter 30 impresses an output voltage and heat - the transformer is mainly located in parallel with the fluorescent lamp a LAI, a voltage is impressed on the secondary windings of the heat transformer. Each of the two secondary windings supplies potential-free one of the two heating windings H1,H2 and H3,H4. The sum of the heating wire currents IW1 is then measured on the primary-side measuring resistor RIO. The further series-connected Zener diode V15 generates in the primary winding of L5 a direct current component, which, however, is not transmitted, but which is missing in the lamp current IL1 and thereby supplies the lamp discharge with an additional direct current component of the order of approx. 1% of the actual discharge current. This prevents the effect of "running layer", which occurs when dimming the lamps. The "running layers" consist of light/dark zones that especially appear when dimming and which run along the pipes at a given speed. The superimposition of a small direct current accelerates this running effect in such a way that it no longer acts as a disturbance.

For heating, the inverter 30 is driven with a high frequency fmax so that an alternating voltage appears on the capacitor C17, which voltage is not suitable for lighting the lamp LAI. In this operating condition, the heating coil or wire winding of the lamp is heated above L5, whereby, depending on the cold conductor effect of the wires, the lamp first takes up a high and then a lower heat current. After about 750 msec of preheating time, the ignition (ON) of the lamp is initiated.

When the fluorescent lamp is switched on, the frequency f of the inverter 30 is reduced so that it approaches the resonant frequency f of the output series resonant circuit L2,C15. Thereby, a voltage increase occurs on C17 which is of the order of magnitude approx. 750 V (peak). Thereby, a functional lamp is lit.

As soon as the lamp LAI or LA2 has lit, the series resonant circuit L2,C15 or L3,C16 is strongly damped. This causes, firstly, a shift in the resonance frequency f0 and, secondly, an immediate lowering of the alternating voltage on the lamp in question. The lowering is registered by the control and regulation circuit 17 via the voltage divider R27, R25 which is connected in parallel with the lamp. This circuit then initiates the actual operating phase (DIM) of the lamps.

For efficient operation of the lamp, the frequency f of the inverter 30 is regulated so that the power of the lamp corresponds to the predetermined nominal value, i.e. the desired brightness level. The higher the operating frequency, the lower the lamp brightness. The operating frequency of the alternating voltage generator 30 can thereby also be shifted to values in the order of magnitude of the heating frequency or above this. At maximum load (MAX), an output frequency can also be set that is below the ignition frequency, but still above the resonant frequency of the series resonant circuit L2,C15. The operating state of the lamp circuit 14 can vary greatly depending on the inserted lamp, for example an argon or krypton lamp, or depending on the selected lamp power.

The combination from the capacitor C24 and the diodes V3 0,V31 causes a frequency-dependent damping of the output circuit when the voltage is increased. It is particularly important when high frequencies and high impedances occur, i.e. e.g. in the event of a missing lamp or preheating of an already hot coil or wire winding. Such a connection helps to limit the voltage increase in the event of a non-lit or missing lamp, if such an increase is undesirable. C24 is chosen so that the damping at the time of ignition remains sufficiently small.

Fig. 6 shows the output circuit in Fig. 5 for two-flame operation, i.e. two fluorescent lamps on an inverter. The symmetry transformer TRI is also fully drawn here. One of the two lamp currents flows through each winding. This occurs against each other so that in the event of current amplitude deviations, a resulting magnetization occurs which induces a voltage which has a symmetrizing effect in the inductive element. Such a transformer is advantageous if component tolerances and lamp tolerances as well as different temperature conditions in the lamps would cause them to glow with different brightness in the dimmed state. With the help of the symmetry element TRI, this effect is avoided with two-lamp lighting. If several pairs of lamps are operated on one alternating voltage generator output, such a symmetry element TRI must be arranged for each pair.

From Fig. 6 it is further clear that in front of each fluorescent lamp an individual series resonance circuit is connected and an individual ignition capacitor C17, C18 is connected in parallel. This enables a relatively independent ignition phase as well as synchronization during dimming operation. Parallel to the ignition capacitor C17, C18 is then a voltage divider R25-R28 which carries a signal proportional to the output AC voltage to the control and regulation device 17. In the same way, it is also possible to connect the voltage dividers directly in parallel with the fluorescent lamp, i.e. .behind the symmetry element TRI.

In series with the lamps, which has already been described for a lamp circuit in Fig. 5, a current measuring shunt R31, R32 is arranged for each one. On these, a signal is taken out which is proportional to the lamp current and which in the control and regulation circuit 17 can be multiplied by the aforementioned lamp voltage signal. In this way, it is ensured that a signal is available at all times which is proportional to the actual lamp power Pnom, respectively the brightness E, and which can be preset as an instantaneous value for precise brightness regulation.

Fig. 7 shows in detail the inverter 30 with its output power transistors V28, V21. Between these, the high-frequency alternating voltage UHF is emitted on the previously described load circuit 40. Both power transistors are controlled via a control circuit 31 which receives its control signal from the control and regulation circuit 17. Asymmetric switch-off or switch-on delays can occur for the transistors in question so that, in principle, a joint control of both transistors V21, V28 can be avoided. The upper transistor is fed via a (not shown) bootstrap circuit, the lower transistor and the system controller 10,17,31 receive their control voltage via a pre-resistor and a smoothing capacitor C5 from the intermediate circuit voltage U0. Next to the aforementioned power supply from the intermediate circuit, an alternating voltage coupling with low loss from the oscillating inverter 30 via a coupling capacitor C21, the diodes V12, V7 and the inductance L7 in the storage capacity C5 also takes place.

The current supplied to the smoothing capacitor C5 through the pre-resistor or a current source Iq is sufficient to supply IC31 and the control and regulation circuit 17 in disconnected operation

(SLEEP).

When operating the inverter, it is sufficient

load-connected supply which is disconnected via a capacitor C21, rectified via the aforementioned components V12,V7,L7 and smoothed via C5. This supply voltage extraction is almost lossless as only reactive elements are inserted for current limitation. By means of the antiparallel diodes V14, V15 which are connected in the lower inverter half branch of the transistor V21 and the resistor R34 connected in parallel with these, a branch current Imax is produced which is proportional to the voltage signal UKap. Like the other process signals, this is fed to the control and regulation circuit 17. Based on this, this can determine the current direction of the current flowing through the inverter at the moment before the opening of V21. If this current is negative, then the load circuit 40 of the inverter 30 is

in an unacceptable capacitive range. It thereby poses a danger to the controlling inverter. Next to the pure amplitude detection, a phase state determination can also be made, where the load current IL1 is set in relation to the inverter branch current Imax/ and from this the relative phase of both currents can be produced for detecting the operating state.

Recognition of an inadmissible capacitive operating condition is answered by the control circuit 17 with an increase in the operating frequency f of the inverter 30, whereby the load circuit 40 is again operated inductively. The aforementioned capacitive mode of operation mainly occurs at low supply voltage. With the help of the branch current detection, damage to building elements can be safely avoided.

Fig. 8 shows the sending and receiving device 10 as well as the upstream connection filter with which the bus connection to the control line 12 takes place. In this example, the nominal values for minimum, maximum and emergency lighting strength (unøD' UMIN' umax) are predetermined for the digital interface 10. Furthermore, a digital input DAT is arranged over which both the control signals from a central control device reach the non-central electronic drive circuit, and which are also notified of the error signals from the non-central drive circuit to the central control device. The serial interface makes it possible to remotely control the electronic drive circuit using a

digital command signal or command word. An 8-bit data word is provided as such a digital signal. This is differentiated by the two capacitors C22, C23, and then by half of the supply voltage to the control circuit 17, respectively sending and

the receiving circuit 10, shifted in potential and then applied to the digital input DAT to the interface 10 over a

damping capacitor C12. Thereby, both the 50 Hz mains frequency can be suppressed and also the input current to each interface can be kept small. Fig. 8b shows a further embodiment of the bus connection. Here, both bus lines 12 are inductively connected to the data input of the digital interface. If drive circuits are operated with

switching filter shown in Fig. 3 in different phases of the three-phase alternating current network, equalizing currents may flow which affect the data transmission in a disruptive way. These equalizing currents can also flow in the circuit according to Fig. 8b. They do, however, tend to increase as no primary side mass connection exists. An advantageous further development of this circuit is shown in Fig. 8c. By using a secondary winding with a middle connection, the circuit becomes pole-safe. It is also possible to use an optical connection, but this entails increased power consumption.

255 brightness values (equivalent to 8 bits) have been set as setting signals. It is also possible with the control signal "OUT" indicated by the binary word "Zero". With the help of the aforementioned signal UT, the total drive circuit moves immediately or after a short period of time to a power-saving switch-off mode (SLEEP). In this mode, the measurement current consumption of the entire drive circuit is minimal. The inverter 30 and the control circuit 31 are taken out of operation, and possibly after a small time delay, also the essential parts of the control and regulation circuit 17. It is only the receiving circuit of the transmitting and receiving device 10 and the monitoring circuit for recording emergency operation (NØD) which remains activated. The power consumption for the entire circuit thus drops to below 1 W. If a new setting signal is received in such a state, however, the control and regulation circuit 17 immediately performs the switch-on sequence which, with preheating and ignition sequence (TENN), leads to stationary operation, and it immediately provided for immediate setting of the desired brightness values (DIM).

In addition to controlling the brightness and the emergency lighting mode as well as the switch-off mode (SLEEP mode), the control and regulation circuit 17 also has the task of retrieving information that is important for monitoring and controlling the drive circuit, from all the aforementioned process parameters.

These are the voltage monitoring, emergency operation maintenance and monitoring of the fluorescent lamps with regard to coil breakage or gas failure. Furthermore, the different operating states of the fluorescent tubes, such as ignition, preheating and stationary operation, can be distinguished using the measurement variables. In the following, the process variables that have been measured and highlighted for further control will be summarized:

Supply voltage Uac,UN,

under/overvoltage UNmin, UNraax, battery voltage UB,

intermediate circuit voltage U0,<U>dc,

lamp current/operating current IL1,IL2'

lamp voltage UL1,<U>L2/

output voltage UHF,

output current IHF,

spiral or wire current IWi'<I>W2'

alternating voltage generator branch current IKap •

On the basis of the listed sizes, overvoltage and undervoltage in the intermediate circuit and in the supply circuit are recorded. The control and regulation circuit 17 thereby switches off all the functions when the voltage becomes too high, and can only come back into operation when the voltage has first been switched off and is switched on again. The occurrence of undervoltage, which leads to a dangerous capacitive operation of the inverter, is answered by blocking the control circuit 31. As long as the mains supply does not have the necessary voltage to guarantee the heating process of the heating wire and avoid capacitive operation, the control and regulation device 17 does not ignite. Only after exceeding a predetermined threshold value is the ignition sequence triggered. This happens automatically.

An emergency switchover to a predicted emergency lighting brightness takes place, e.g. when a direct voltage UN is detected by the control circuit 17 across the normal alternating voltage feed input to the switching circuit 20 and across the measuring sensor R21,C25 (Fig.4). This is done by a counting logic which, in the absence of exceeding or falling below a predicted threshold value, initiates the emergency operation. This can happen after a predetermined dead time that goes over certain, possibly missing, half-waves.

If the normal AC supply voltage Uac, UN in a lighting system fails, an emergency supply voltage UB, which comes from batteries or a generator, is applied to the mains voltage line. The electronic drive circuits register this automatically in the so-called

In case of emergency operation, the brightness of the fluorescent lamps is no longer given by the digitally preset brightness value DIM, but set using a decentralized trimming value on the device, which trimming value can be preset via the input EMERGENCY. If the drive circuit is in switch-off mode (SLEEP) when this emergency mode is entered, i.e. with the lamp and the inverter switched off, it first carries out a normal ignition cycle (ON) and then adjusts to emergency mode brightness.

At the recognized end of the emergency operating state, the electronic drive circuit returns to the previous state, which can be the UT state if the drive circuit was there beforehand. However, it can also be the original brightness value (DIM), if this was the condition before the requirement for emergency operation existed.

When registering the spiral or wire current, an identification is made as to whether a lamp has not been inserted or whether one of the two wires is broken. In one of these failure cases, the inverter 30 is operated at its maximum frequency fmax/which firstly results in a heat current flowing when the defective lamp is replaced, and secondly that the voltage on the defective lamp is reduced to the lowest possible. This is important for compliance with the safety regulations according to VDE. At the aforementioned high frequency fmaxi, the inductive part of the series resonance circuit at the output becomes so high in relation to the capacitive resistance of the ignition capacitor C17 that the voltage at the output is limited to harmless values, and there is no danger to the operating personnel.

When a functioning lamp is inserted, after the warm-up time, the ignition sequence (TENN) is initiated without further measures.

The internal progress control in the control and regulation circuit 17 further also limits the number of start attempts to two, and then always sets (sends) an error signal via the sending and receiving device 10 on the two-way bus 12 when there is an error case, e.g. if the lamp is missing, if there is a break in the heating coil or a gas fault. This also applies to emergency operation, as lamp failure does not stop emergency operation.

Faults in the wiring leading to short-circuiting of the lamp's discharge path can, due to the process signals, be detected when the lamp voltages are monitored at a predetermined minimum value. At the same time, falling below this predetermined value, as in the case of net overvoltage monitoring, leads to disconnection of the entire electronic drive circuit.

Also difficulty in lighting the lamp, e.g. due to gas failure, is registered by the control and regulation circuit 17. If the lamp in an ignition attempt is not lit within a predetermined ignition time, i.e. if there is no drop in the voltage on the ignition capacitor C17 during this time period, the aforementioned latch intervenes.

In addition to complete disconnection and an error message, one can also wait for a repetition time, after which a renewed ignition and start attempt is made. If there is no ignition either, the control and regulation circuit 17 reacts as in the event of a heating wire break and sets the frequency of the inverter 3 0 to the maximum value<f>max-

When replacing a lamp, which the control and regulation circuit 17 detects when the lamp voltage rises or a change in the heating wire current, a new ignition attempt takes place after re-inserting a new lamp.

Regulation of the brightness of the fluorescent lamps shall be explained in the following. A real brightness regulation takes place, which regardless of the lamp type gives the same lamp effect - with essentially the same lamp efficiency. The instantaneous value-determining measured quantities lamp current, lamp voltage are multiplied and analogically or digitally compared with the nominal or fixed values remotely controlled by the sending and receiving device 10. The comparison result directly or via a regulation device controls the frequency f of the alternating voltage generator 30. If more accurate brightness division is desired, a logarithmic nominal value adjustment can be arranged. In the same way, an exponential instantaneous valuation can be carried out. In addition to lamp type independence, compensation is also achieved for the age of the lamp, the relevant operating temperature and also for possible fluctuating mains voltage UN.

With the process signal-controlled operating state monitoring, it is also possible to light the lamp at low brightness values, whereby the normally occurring light pulse can be avoided. This depends on the energy stored in the output circuit during the ignition process, which after ignition is discharged in the lamp as a shock. For suppression or removal, a rapid ignition registration and a rapid reduction of the lamp current after ignition is ensured - by changing the lamp ignition voltage<U>L1,<U>L2. The latter occurs by instantaneous displacement of the inverter output frequency in the direction of higher frequencies. In this way, the mica area between the ignition and the stationary gas discharge is artificially extended. This would normally lead to a reduction in lamp life. However, this is avoided in the design example because extension of the glow phase only takes place for the critical low brightness values. For large brightness values, the current is kept at a higher level, whereby the glow phase is shortened. This can be set per software using digital control words and the sending and receiving device 10.

Fig. 9 shows a brightness-time diagram where the brightness of the lamp is controlled by the drive circuit according to Fig.

1 is varied depending on time. First, the maximum brightness is determined followed by a cut-off cycle predetermined over the bus line 12 and the digital interface 10. The brightness is reduced to zero after a predetermined increase, and then the inverter 30, its drive circuit 31 and significant parts of the control IC 17 switch off to save power. The subsequent emergency lighting condition leads - despite the disconnected system - to a controlled ignition and build-up of the lamp brightness to the preset emergency lighting intensity (EMERGENCY). This can be changed by changing the preset nominal value UNÉD for each decentralized drive circuit. Likewise, the maximum" and minimum brightness value (MIN,MAX) shown in Fig. 9 can be set or equalized by pre-setting a corresponding nominal value.

Fig. 10 schematically shows a program-technically controlled "soft start" as a brightness-time diagram. The electronic drive circuit 60 is initially in the disengaged state (UT). The "soft start" command now leads either to an automatic ramp-regulated increase in lamp brightness - after switching on the lamp - or to a program-controlled incremental increase in lamp brightness steps. In the latter case, incrementally increasing brightness values are sent out at specific time intervals from the central control device 50. The non-central drive circuits perform the tasks almost without delay. This enables a change rate-controlled (regulated) rise and fall of the brightness of the non-central light sources.

Claims (38)

1. System for monitoring and remote control of one or more electronic drive circuits (EVG 60-1 to 60-i) for gas discharge lamps (LAI, LA2) from a central control device (50, 51), where each drive circuit includes a rectifier circuit (GR, 20 ) that can be linked to the alternating current grid (mains), an alternating voltage generator (30, WR) which is fed from the rectifier circuit (GR, 20) and has variable output frequency (U^p), a load circuit (40) containing at least one series swing circuit (L3, C14) and at least one gas discharge lamp (LAI, LA2) and which is fed from the alternating voltage generator (3 0) with its variable output frequency (UHF), characterized in that (a) the central control device (50, 51) is connected to each electronic drive circuit (EVG 60-i 60-i) via respective bus wire pairs or via a single, common bus wire pair (12), contains funds for the provision of digital governance signals for the operating state, such as emergency, sleep, ignition, off or on state and the lamp brightness (<E>nom) and/or lamp power (<P>nom) for each electronic drive circuit, as well as to emit these control signals to the corresponding bus line pair (12), and contains means to receive and to assess digital error messages and/or digital operating status information that is transmitted from each electronic drive circuit to the corresponding bus line (12), (b) each electronic drive circuit (EVG 60-1 to 60-i) in addition includes a digital interface (10) designed as sending and receiver device and connected to the corresponding bus wire pair (12) to receive the digital control signals emitted from the central control device and to issue digital error messages and/or digital operating status information to the central control device, and a control device (17) connected to the digital the interface (10), which control device evaluates the digital control signals transmitted to it from the digital interface (10) in order to control or regulate the electronic drive circuit, and which control device evaluates measured value signals (UL1,<U>L2, Irøi/Irø2'<U >dc,<U>ac) which is recorded from the electronic drive circuit, and produces digital error messages and operating status information from these and transfers this to the digital interface (10). 2. System according to claim 1, characterized in that the control device (17) for each electronic drive circuit also acts as a regulation device, in that it evaluates the measured value signals (UL1, UL2/■^Wl'<I>W2/ udc<u>ac^ as ^-a vessel taken°PP as actual values and the control signals that are supplied to it centrally indirectly via the digital interface and/or directly, as nominal values, and produce digital control signals for regulating the output frequency (Ujjp) of the alternating voltage generator (3 0) in accordance with this. 3. System according to claim 1 or 2, characterized in that in the rejection operating state, where the gas discharge lamp is switched off, the alternating voltage generator (WR, 30) is put out of operation via a drive circuit (31) and the control device (17) immediately or after a predetermined period of time (sleep operation). 4. System according to claim 3, characterized in that the control device (17) is taken out of operation at the same time as the alternating voltage generator (WR, 30) or slightly delayed in relation to this, and that upon receipt of a new digital brightness order, the control device (17) and the alternating voltage generator (30) are activated again . 5. System according to claim 1 or 2, characterized in that a change in one of the supply voltages (Uj^, Uac) which feeds the rectifier circuit (20) is registered, and that the control device (17) then changes the operating state of the GE lamp (LAI, LA2) and /or brightness (E) correspondingly, and in particular sets an emergency lighting level (EMERGENCY) which can be given in advance, when registering direct voltage (UB). 6. System according to claim 1, 2 or 5, characterized in that a change in an intermediate circuit direct voltage (UQ, U^c) which feeds the alternating voltage generator (30) is registered before and/or during stationary operation, and then the GE lamp's ( LAI, LA2) operating condition is affected accordingly, and in particular with shutdown when an overvoltage value (Ujjmax) is exceeded that can be given in advance, and with failure to ignite when an undervoltage value is exceeded (UNmj_n). 7. System according to one of claims 1, 2, 5 or 6, characterized in that capture of a direct voltage (UB) that feeds the electronic drive circuit (60) instead of a regular supply alternating voltage (UN, Uac) can be registered via a counter logic , which monitors or registers the time interval for the appearance of a threshold value in the supply voltage (UN, UB), which threshold value can be given in advance. 8. System according to one of the preceding claims, characterized in that the emergency lighting level set in advance by means of a setting device (R7, C28, R6) takes precedence over a brightness level set by means of command words and the possibly present rejection state , for example the off or sleep state. 9. System according to claim 8, characterized by the fact that after activation of the emergency lighting level follows a return to the rejection operating state, when the latter has existed before activation of the emergency lighting level. 10. System according to one of the preceding claims, characterized in that more preset nominal values (NØD, TRI, TR2) than the brightness level of the GE lamp can be given in advance to each control device (17) or each interface (10) by means of the potentiometer, trimming resistors or voltage dividers (R2, R6, R7, R32, R33), which can be called up individually via command words to the digital interface (10) or can be set by the control device (17) via the alternating voltage generator (30) by The GE lamp (e) (40) . 11. System according to one of claims 2-10, characterized in that the dimmed brightness values are changed via a logarithmic or exponentially acting function element in the nominal value channel or in the actual value channel for the brightness control circuit (Pnom, Efak)• 12. System according to one of the preceding claims, characterized in that the control and/or regulation of brightness (E) and operating state for the GE lamp (LAI, LA2) is effected by a frequency change (f) in the alternating voltage (UHp) which is emitted from the alternating voltage generator (40) ), or that a frequency change (f) and a pulse ratio change in the alternating voltage (UHF) are carried out for brightness change (Efajc) for the GE lamp, whereby the pulse ratio is especially chosen lower in the lower dimming range. 13. System according to one of the preceding claims, characterized in that the digital control signals are supplied to each digital interface (10) and each control device (17) in each associated electronic drive circuit (EVG 60-1 to 60-i) as instruction words, especially with 8 bits word length, serially over the bus wire pair (12) . 14. System according to claim 13, characterized in that each connected electronic drive circuit (EVG 60-1 to 60-i) can be called up and controlled, and especially dimmed, individually or in "function groups" using the instruction words. 15. System according to claim 13 or 14, characterized in that the serial instruction words are supplied via a bandpass or a differentiation element (C22, C23, R4, R5, C12) in the digital interface (10). 16. System according to claim 13 or 14, characterized in that the serial instruction words are supplied inductively via a converter in the digital interface (10). 17. System according to one of the preceding claims, characterized in that in order to avoid parasitic light pulses during an ignition sequence, a rapid ignition registration is provided, and that when an ignition is determined, a rapid reduction of the lamp current is made. 18. System according to claim 17, characterized in that the reduction of the lamp current is realized by instantaneous displacement of the inverter's output frequency (f) in the direction towards higher frequencies. 19. System according to claim 17 or 18, characterized in that the time duration of the glow phase between ignition sequence and stationary normal or dimming operation is changed depending on the stationary brightness. 20. System according to claim 19, characterized in that the duration of the flash phase for weak, stationary luminosities is extended. 21. System according to one of the preceding claims, characterized in that the brightness is brought from the off state for the gas discharge lamp to the desired, stationary brightness through a collection command or rate of change controlled by means of incremental dimming instructions, or is brought in the opposite direction. 22. System according to one of the preceding claims, characterized in that after a predetermined number, in particular two, fruitless ignition attempts for the GE lamp (e) (LAI, LA2), further ignition attempts are prevented by an internal ramp control. 23. System according to claim 22, characterized in that the internal ramp control initiates further ignition attempts after the obstruction of ignition attempts, if the lamp is replaced. 24. System according to one of the preceding claims, characterized in that the control device (17) can be supplied with a plurality (m) of measured value signals, such as lamp current (<I>L1,<I>l2')'lamp alternating voltage (UL1,<U>L2)• heating wire current (IW1, 1^2)'alternating voltage generator branch current (i^Ap), inverter output voltage (UHF), intermediate circuit direct voltage (U^, Uq), direct and decentralized, as well as a plurality (n) nominal value quantities such as emergency lighting level , upper and lower brightness limit value and operating brightness level (Enom, Pnom)/either directly decentralized or indirectly and centrally over the interface (10). 25. System according to claim 24, characterized in that the actual lamp power (Pfak) or brightness (Efak) is determined from the required lamp current (Il]_/^l2^°9lamp voltage (<U>L1,<U>L2) and is comparable to a brightness value (Pno<m>,Enorn) which can be provided centrally in advance, and that on the basis of differential signals, a frequency change (f) is made for the decentralized alternating voltage generator (30) in the electronic drive circuit (EVG 60-i). 26. System according to claim 24 or 25, characterized in that the control device (17) registers a capacitive operation of the load circuit (4 0) based on the measured value signals lamp current (I^, ^L2^ 0<3 alternating voltage generator output voltage (UHF) by comparing their zero crossings or of the relative phase between both measurement quantities (UHF, Ili» -"-L2^ '°3at vec^ registration of such a mode of operation shifts the frequency (f) of the alternating voltage generator (30) upwards. 27. System according to one of claims 24-26, characterized in that the measurement value heating wire current (<I>røi/ ^W2^) is monitored with regard to the fact that it may exceed a pre-given threshold value, and that if it falls below the aforementioned threshold value, the alternating voltage generator is shifted (30) of the control device (70) towards its maximum frequency (<f>max)/ and that a digital error signal is emitted through the interface (10). 28. System according to claim 27, characterized in that the measurement value heating wire current drøi/<!>w2^ is also monitored while the alternating voltage generator (30) is working at maximum frequency, in order to initiate a new start upon registration of a newly inserted lamp. 29. System according to one of claims 24-28, characterized in that an insignificant direct current component can be superimposed on the lamp current (Il]_, IL2)' which direct current component preferably lies in the area with a weak brightness value for the GE lamp (LAI, LA2), and which direct current component in particular makes up 1% of the lamp current. 30. System according to one of claims 12, 24 or 25, characterized in that the change in the frequency (f) of the alternating voltage generator (30) is effected by means of a voltage-controlled oscillator (VCO) in the control device (17). 31. System according to claim 24 or 25, characterized in that in the case of emergency operation, the previously centrally given brightness value (<P>noin,<E>nom) is replaced with the previously decentralized and previously given emergency lighting level for this respective control device (17) for each electronic drive circuit (EVG 60-i). 32. System according to one of the preceding claims, characterized in that the electronic drive circuit (EVG 60-1 to 60-i) has at least a pair of series resonant circuits (L2, C15, L3, C16), which connects the output of the alternator (30, WR) to each of a pair of gas discharge lamps (LAI, LA2, GE lamp), at least a pair of ignition capacitors (C17, C18), of which each single in a pair is connected in parallel with each individual in a pair of GE lamps (LAI, LA2), and at least one inductive symmetry element (TRI) which is opposite magnetizable by the lamp current (Ili»Il2^ ^or nver in a pair of GE lamps (LAI, LA2). 33. System according to claim 32, characterized in that the ignition capacitor (C17, C18) strikes between the coil (L2, L3) and the capacitor (C15, C16) in the series resonant circuit. 34. System according to claim 32 or 33, characterized in that the symmetry element (TRI) is a two-winding transformer, where both windings have the same number of turns. 35. System according to one of the claims 32-34, characterized in that at least a pair of current measuring elements (R31, R32) are arranged, preferably a pair of low-resistance shunt resistors, whereby each current measuring element (R31, R32) is connected in series with a respective gas discharge lamp, that at least a pair of voltage measuring elements (R25-R28), preferably a pair of voltage dividers, are arranged, whereby each individual voltage measuring element (R25, R27, R26, R28) is connected in parallel with a respective gas discharge lamp, and that all measurement quantities (UL1, UL2»<*>L1'<i>L2^ taken from the measuring elements are supplied to the control and/or regulation device.; 36. System according to one of claims 32-35, characterized in that the heating wires in each individual gas discharge lamp can be heated in a voltage-controlled manner by a respective heating transformer (L5, L4) with a primary and a respective secondary winding for each heating wire in the gas discharge lamp, whereby each heating transformer (L4, L5) is connected on its primary side in parallel with the gas discharge lamp in which it heats the heating wires.; 37. System according to claim 36, characterized in that each heating transformer (L4, L5) on its primary side is connected in series with a respective current-measuring element (RIO, Ril), whose instantaneous output signal (Ili*- iL2^ ^an is output to control and/or the regulating device (17) for detecting the nature of the heating wire and for deriving an error signal. 38. System according to claim 29 and claim 32 or 36, characterized in that the direct current components in the lamp current are effected by means of a Zener diode (V16, V17), which Zener diode is connected in series with the heating transformer or transformers (L4, L5).