Process and circuit for controlling the light intensity and the behaviour of gas discharge lamps

0001The present invention relates to a method and a circuit arrangement for Controlling the brightness and the operating behavior of gas discharge lamps.

0002Electronic ballasts modern construction are used to activate Fluorescent lamps. The lamps are tested for a gentler and operated on the other hand, the efficiency of such types of lamps be increased. An electronic ballast regularly in this case has the following characteristics:

0003About a mains input filter is a supply voltage, the direct one or can be AC ​​voltage, a rectifier and an intermediate capacitor supplied. As far as the device is operated with DC voltage, can the rectifier also be omitted. On your link capacitor is a high Intermediate circuit voltage U₀ formed of at ordinary mains supply 220 V is in the order of about 300 volts. At the intermediate circle closes an AC generator on, is of a half-bridge or this Full-bridge inverter formed. He is a variable frequency output voltage with to an output load circuit from which, if no half-bridge circuit artificial Spannungsmittelabgriff is provided, having a series resonant circuit. In series with the series resonant circuit the discharge path to be controlled which is Gas discharge lamp or fluorescent lamp.

0004The output frequency of the inverter is approximately 10 kHz to 50 kHz.

0005In the aforementioned frequencies, the efficiency of the connected is Fluorescent lamps compared to an operating in the 50 Hz power supply increases. Increased indicative yield is obtained for the same electrical power. Furthermore, due to the high frequency, the inverter-output-side Inductance of the series resonant circuit are kept small. Finally permits variable frequency control a brightness control of said - at normal power difficulties brightness adjustable (dimmable) - fluorescent lamp. Come in addition finally, that on the frequency control and an ignition of the fluorescent lamp can be prepared and initiated.

0006To the aforementioned ignition part to protect the fluorescent lamps also a so-called warm start, when your the heating coils of the fluorescent lamp preheated be before the lamp due to resonance phenomena with a high Ignition voltage is applied, the ignition and thus to operate the Gas discharge lamp leads. The variation of the frequency, which the ignition controlled, allows the operation of the gas discharge lamp by Frequency shift an almost continuous brightness control within wide limits. Such continuous and continuous control of the brightness requires due the negative internal resistance of the in-use fluorescent lamp special Measures.

0007In addition to a versatile control and regulation is a major concern modern electronic ballasts, comfortable handling and operation of many decentralized light sources arranged to ensure. This particular with regard to Large projects where extensive lighting systems with a large number of Light sources are to be installed.

0008Furthermore, should an increased safety for the connected fluorescent lamps and improved monitoring ability of these are created. no security has recently also for the operating personnel to change the failed lamps and this is dependent on that and to replace the lamp at the Jacks heat in the unit voltages are not dangerous. This for the reason that since extensive lighting systems, the individual lamps can be switched off individually not are such that a lamp change during operation is necessary.

0009forms the central point for the development of a modern electronic ballasts However versatile as possible control option, in particular a Brightness control. This in view of the operating behavior and the Brightness control of devices connected to each Einein Fluorescent lamps. Here the most accurate brightness adjustment should be achieved.

0010A process described in US-4,523 128 ballast has for this purpose a Control means, via the power supply line by means of power line carrier Method (PLC) digital control commands to be supplied. These digital control commands particular include dimming value for controlling the brightness of the lamp. they be decoded in a decoding device and converted into control signals for driving implemented the inverter, so that the desired lamp brightness is achieved. Thus each Dimmwertbefehl corresponds exactly to a brightness value, as a result, that control of the lamp brightness is not continuous but in Brightness stages. Since the digital control commands, however a given Length (for example, a length of eight bits) have is the number of Dimming value and thus limits the available brightness levels.

0011It is therefore an object of the present invention to provide a method and an Circuit arrangement for controlling the brightness and the operating behavior of specify gas discharge lamps, at your an implementation of the limited available stationary digital Dimmwerrbefehle is performed so that over a large as possible achieved brightness range most accurate regulation of the lamp brightness becomes.

0012The object is achieved by a method and a circuit arrangement with the Features of claims 1 and 2, respectively solved.

0013The inventive solution ermöglichst it, the control functions and the Brightness control especially to handle accurately and comfortably. About a one Control and regulating device assigned interface can control commands and Brightness commands are supplied by the control and regulating device depending on the process variables currently in force (measured values) of the respective Ballast to run. Here each corresponding with a digital Command signal representing a setpoint brightness of the lamp.

0014According to the invention, the control and regulating device is so designed that the through the digital setpoints related brightness levels, so the differences in brightness between two adjacent - each corresponding to a digital setpoint - Brightness values ​​are incrementally increasing. As a consequence, the Brightness difference between adjacent brightness values ​​at low lamp is darker than in high lamp brightness. It exceeds However, the relative change in lamp brightness at a change from a Brightness value for not following a predetermined limit.

0015In a particularly preferred case, the relative change is when switching between adjacent brightness values ​​even constant, giving a logarithmic Dimming characteristic results. The advantage of this method of the invention is to see that the limited available digital dimming value effectively can be utilized and the gas discharge lamp in a substantially larger can operate brightness range.

0016Previously it was known to use linear dimming characteristics, which, however, only represent a compromise solution. Target namely the use of a linear dimming characteristic in the lower brightness range accurate and fine be achieved brightness control, so very little brightness levels have chosen be, but this in turn means that only a small range of brightness total can be controlled. The absolute and relative differences in brightness when Alternating between two brightness values ​​are then unnecessarily small in bright light. In contrast, if the largest possible range of brightness by a linear dimming characteristic be detected, are inevitably at the little brightness values ​​the differences big. A change between adjacent brightness values ​​is then used as jump perceived.

0017Such drawbacks are the by the inventive incremental increase Brightness levels avoided.

0018In addition to convenient brightness control allows the control and regulating device also targeted an increase in the service life of the fluorescent lamps and a Granting of security interests. With their help, the performance and the respective Berriebszustand of by a TOE supplied fluorescent lamp are strictly controlled and monitored. So be warm start, ignition, dimming and Shutdown (ZÜND; DIMM, OFF, ON) with high precision and gentle on lamps strung together. be Unacceptable operating conditions avoided prior to each ignition for a sufficient preheating Heating coils provided. In addition to the inventive brilliance regulated Dimming (DIMM), also the total EDC, if it has not brightness be desired, shut down (SLEEP). In this state, the TOE only accepts minimum power, thereby avoidable losses are virtually eliminated.

0019Based on the drawings below embodiments of the invention explained in more detail. Show it:<dl tsize="10"><dt>Fig. 1</dt><dd>a block diagram of an electronic ballast according to the present invention,</dd><dt>FIG. 2</dt><dd>a block diagram of a systems approach, in which several decentralized ECGs are connected to a central control unit via a bus line, </dd><dt>Fig. 3</dt><dd>a block diagram of one embodiment of the control and regulating device as an integrated circuit,</dd><dt>Fig. 4</dt><dd>a schematic diagram of an input circuit with two Meßwerterfassungen,</dd><dt>Fig. 5</dt><dd>An embodiment of the transformative gated coupling part Wend same heating a Fluorescent lamp with three sensors,</dd><dt>Fig. 6</dt><dd>an embodiment of an output circuit with a Symmetrierelement for two fluorescent lamps,</dd><dt>Fig. 7</dt><dd>a schematic diagram of the AC generator with him-addressing Driver circuit,</dd><dt>FIG. 8a-c</dt><dd>are each a block diagram of the transmitting and receiving device with differently configured coupling circuits to the bus cable,</dd><dt>Fig. 9</dt><dd>a brightness time chart for explaining the turn-off and the Emergency operation,</dd><dt>Fig. 10</dt><dd>a brightness time chart for explaining the soft start and soft stop function at a system configuration according to FIG. 2.</dd></dl>

0020<b>Fig. 1</b> initially shows a block diagram of one embodiment of the invention ECGs. The mains voltage U_N is - possibly via a switch S1 - the Eingangssehaltkreis 20 (rectifier circuit) is supplied. This creates the Intermediate circuit voltage U₀, U_dcThat the AC voltage generator 30 (Inverter) is supplied. The AC voltage generator 30 are his high-frequency output voltage U_HF to an output load circuit 40 from which a or more fluorescent lamps LA1, LA2 contains. Both the AC voltage generator 30 and the load circuit 40 are a plurality of System-measured values ​​(process variables) can be removed. Together, the measured values ​​are a And control circuit 17 which in turn, the digital control signals for the inverter generates 30th These will be via a driver circuit 31 potential shifted and supplied to the output MOS-FETs of the inverter. Of the Control and regulating device 17 is also a transmitting and receiving device 10 assigned to via a bus line 12 to other electronic ballasts and / or with a central Control unit 50 is connected.

0021The latter is of <b>FIG. 2</b> shown. There are a plurality of electronic ballasts 60-1,60-2,60-3, ..., 60-i connected to a common bus line 12th All ECGs are this Bus line connected to the central control unit 50, a display unit 51 associated with the is. It is via the bus line 12 is now possible, one or more of the said to control ballasts and to give commands like switching off, turning on, Ignition o. Ä. Also brightness values ​​can be preset and in return Error information is extracted from each device. Thus, the control device 50 at all times about the overall system state, thereby providing a high level of operational safety may be granted and an accelerated maintenance of decentralized ECGs, or for their lamps, is possible.

0022The functional blocks shown in FIG. 1 20,30,40,10,17 be apparent from the following FIGS now explained in detail.

0023<b>Fig. 3</b> this is shown in the control and regulating device 17 as an integrated circuit. you are the plurality of measured values ​​of m, which process the signals of Figs. 1 correspond, respectively. They are two digital control signals for the output transistors of the inverter 30 from that intensified via a driver circuit 31 and potential shifted.

0024In addition to the m measured values ​​of the control and regulating device 17 be n setpoints supplied. This influence can be predetermined and control behavior. It is further as part of the control and regulation circuit 17 or separately transmit and Receiving means 10 provided the coupling circuit directly or by means of a is connected to the bus line 12th It forms the serial interface, which the Control and regulating device enables error and operating status information the central control device 50 to transmit.

0025The n reference values ​​mentioned above can also this transmitting and receiving device 10 are fed, they after appropriate treatment for the control and regulation circuit 17 passes. Setpoints can for example be the emergency level (NOT), the minimum brightness level (MIN) and the maximum brightness level (MAX), within the latter two can be the predetermined brightness level (DIMM) in moving operation.

0026As instruction and data words and an error information words are serial digital Data words used, whose length is 8 bits. Other value lengths are possible. Every decentralized TOE is assigned an address which enables individual ECGs via to address and information, the address of the transmitting and receiving device 10 of interrogate them or to give them orders. The bidirectional operation the bus line 12 enables trouble and expense poor wiring a Variety of decentralized electronic ballasts with a central control unit (50).

0027<b>Fig. 4</b> shows a schematic diagram of an input circuit, as the power to AC generator 30 from a supply network to the voltage U_Nis usable. The input circuit consists of capacitive input filters and possibly from a harmonic choke. The capacitors in star connection are to radio interference suppression. You is connected in parallel a surge or a VDR. It closes a full wave rectifier to which can be omitted if the device operatively is operated with direct voltage. Downstream of the rectifier is a DC link capacitor C4 at 220 V mains voltage to 300 V with the one Ripple of approximately 10% charge.

0028Due to a low-held crest factor, the intermediate circuit voltage U should₀be well smoothed.

0029In parallel with the intermediate circuit capacitor C4, a voltage divider R18, R28, where one of the DC link voltage measurement signal proportional be tapped. on a Lowpass R21, C25 is a supply voltage signal proportional to detected and as well as the intermediate circuit voltage dependent measurement signal to the control and Control device 17 is supplied. Both test signals are used for supply voltage monitoring and therefore the operational reliability of the TOE.

0030<b>Fig. 5</b> shows an embodiment of a load circuit 40 according to the invention with a Heating transformer L5 for the preheating of the filaments of the fluorescent lamp LA1. FIG. 5 is only one shown by a pair of lamp circuits. The embodiment of the invention includes a pair of these branches, that is, two fluorescent lamps LA1, LA2 to an AC voltage generator output, the high-frequency AC voltage U_HF connecting the N See power switching transistors V21 and V28 write. The AC voltage generator from the position shown in Fig. 4 Input circuit 20 with an intermediate circuit voltage U_dc provided. Since the Fluorescent lamps have a negative internal resistance during operation, they must during the ignition (IGN) with high voltage peaks and the heating of the helixes be provided with appropriate heating. Based on the output terminal the inverter 30 performs a seeing resonant circuit L2, C15 via a Symmetrierelement TR1, which will be explained later, on the discharge path H2, H4 of the fluorescent lamp. Furthermore, to the fluorescent tube a measuring resistor R32 in Connected in series, to which a lamp current I_L1 proportional voltage tapped and the control and regulation circuit is supplied to the 17th Between coil L2 and capacitor C15 is connected a starting capacitor C17 to ground (zero). With This arrangement may evened the dimming characteristic of the discharge lamp be because the frequency increases the resistance of the capacitor C15 decreases and the resistance of the discharge lamp increases. In parallel with the starting capacitor C17 is also the primary winding of Heizübertragers and L5 in this further See a Zener diode V15 and a sense resistor R10. On the latter is a the I Heizwendeistrom_W1 tapped proportional voltage and the control and Control circuit 17 is supplied as further Systemmeßgröße. Since the inverter 30 an output voltage imprints and the heating transformer is substantially parallel to Fluorescent lamp LA1 is, is on the heating transformer on its secondary windings a voltage is impressed. The two secondary windings provide each floating one of the two heating coils H1, H2 and H3, H4. On the primary side Measuring resistor R10 as the sum of the I Heizwendelströme_W1 measure.

0031See further connected in zener diode V15 generated in the primary winding of L5 a DC component, but which is not transmitted, but in the lamp current I_L1 missing and thus the discharge of the lamp with an additional DC component supplied in the order of magnitude of approximately 1% of the actual discharge current. This prevents the effect of "running layers" that when dimming the lights occur. The "running layers" consist in particular for dimming occurring light / dark areas, along with a predetermined speed of the run tube. A superimposing low DC accelerated this run effect such that it no longer interferes.

0032For heating, the inverter 30 at a high frequency f_Max operated so that of C17, an alternating voltage occurs, not to ignite the lamp LA1 suitable is. About L5 the filaments of the lamp are heated in this operating state, wherein, due to the PTC effect of the coils, the lamp first high and then receives a lower heating. After about 750 msec preheating the Ignition (IGN) of the air introduced.

0033Upon ignition of the fluorescent lamp, the frequency f of the inverter 30 is reduced, so that it is closer to the resonant frequency f of the output series resonant circuit L2, C15 zoom comes. This results in a C17 Voltage overshoot which is on the order of about 750 V (peak). This is a functional lamp is ignited.

0034Once the lamp LA1 or LA2 has ignited, the series resonant circuit L2, C15 is or L3, C16 highly rejected. This causes a shift of one hand Resonant frequencies f₀ and on the other hand an immediate drop in each of the Lamp lying AC. The decrease is in parallel across the lamp to switched voltage divider R27, R25 detected by the control and regulating circuit 17th This then initiates the actual operating phase (DIMM) of the lamps.

0035For effective operation of the lamp, the frequency f of the inverter 30 is controlled, that the power of the lamp to the predetermined desired value, that is the desired Brightness level corresponds. The higher the frequency in the operating state becomes, the lower the lamp brightness. The operating frequency of the AC generator 30 can certainly shifted to values be lying in the order of the heating frequency or higher. Also, in a maximum power (MAX) an output frequency can be adjusted, the below the ignition frequency, but still above the resonant frequency of the Series resonant circuit L2, C15 is. The operating condition of the lamp circuit 14 may depending on the used lamp, for example, argon, krypton lamp, or dependent on the actual lamp power, vary widely.

0036The combination of the capacitor C24 and the diodes V30, V31 causes a frequency-dependent Damping of the output circuit in voltage overshoot. She is in front particularly important when high frequencies and high impedances occur, eg in the absence of air or during preheating in already warm Wendel. The wiring this type helps the voltage overshoot when unexploded or missing lamp then to limit, if unwanted. C24 is chosen such that the damping of small enough for ignition remains.

0037<b>Fig. 6</b> shows the output circuit of Figure 5 for the two burner -. two lamps on a Wechseirichter - operation. Here also the Symmetieübertrager TR1 is completely located. Each winding of one of the lamp currents both traversed. This is done in the opposite direction, so that at current amplitude deviation resulting magnetization occurs in the inductive element, a voltage induced acting symmetry rend. Such a transformer is advantageous if by component tolerances and lamp tolerances as well as different Temperature conditions different light the two lamps in dimmed state would burn. By symmetry element TR1, this is in two-lamp Lights avoided. If several pairs of lamps on a operated AC generator output, so a pair of each such Symmetrierelement TR1 provide.

0038From Fig. 6 is further seen that each fluorescent lamp, an individual Series resonant circuit is connected upstream and an individual ignition capacitor C17, C18 is connected in parallel. This enables a relatively independent ignition phase and a Synchronism in dimming. In parallel to the firing capacitors C17, C18 is jeweis a voltage divider R25-R28, the one of the AC output voltage proportional to Signal lead to the control and regulating device 17th In the same way it is also possible to switch the voltage divider directly parallel to the fluorescent lamp, ie behind the Symmetierelemente TR1. In series to the lamps, this was based on Fig. 5 explained for a lamp circuit, there is a respective current sensing shunt R31, R32. At them is a lamp current signal proportional won that and in control Control circuit 17 can be multiplied with the aforementioned lamp voltage signal is. In this way it is ensured that at any time one of the actual Lamp power P_is or the brightness E is proportional signal is available, the accurate brightness control as actual value can be predetermined.

0039<b>Fig. 7</b> shows in more detail the inverter 30 with its output power transistors V28, V21. Between them is the high-frequency AC voltage U_HF Add to the aforementioned load circuit 40th In Controls the two power transistors via a driving circuit 31 which his Control signals from the control and regulating circuit 17 receives. If necessary, come unbalanced shutdown / power on delay for the respective transistors in Consideration, so that a common conduction of both transistors V21, V28 fundamentally can be avoided. The upper transistor is a (not illustrated) Bootstrap circuit supplies, the lower transistor and the control system 10,17,31 get their driving voltage through a series resistor and a Glättungskondensaror C5 from the intermediate circuit voltage U₀, In addition to the above Power supply from the DC link is also a low-loss AC-coupling of the oscillating inverter 30 via a Coupling capacitor C21, the diode V12, V7 and the inductor L7 in the Storage place C5.

0040The through the resistor or a current source I_q the smoothing capacitor C5 suppliable current is sufficient to maintain the IC31 and the control and regulating circuit 17 in the off mode (SLEEP) supply.

0041When operating the inverter ranging through a capacitor C21 is coupled out, rectified on the components mentioned V12, V7, L7 and C5 geglätte load coupled Supply. This supply voltage recovery is virtually no loss, since only reactive elements are used for current limiting. By means of the in antiparallel lower inverter half branch of the transistor V21 is switched Diodes V14, V15 and R34 which this parallel resistor is a the Branch current I_Max proportional voltage signal U_cape recovered. This is how the other process signals to the control and regulating circuit 17 supplied. He may therefrom the current direction of by the inverter at the moment prior to the opening of V21 current flowing notice. If this power is negative, then there is the load circuit 40 the inverter 30 in an impermissible capacitive region. He hereby presents a Danger for the controlling inverter. Besides pure amplitude detection can also be used a phase positions of viewing, in which the load current I_L1 with respect to the inverter branch current I_Max is set, and from this the relative Phase of both currents is used for the detection of the operating state.

0042A detection of an impermissible operating capacitive behavior is from the control circuit 17 with an increase in the operating frequency f of the inverter 30 answered, whereby the load circuit 40 is operated again inductive. The aforementioned capacitive operation occurs mainly in low supply voltage. With the Branch current detection, a destroying components are safely avoided.

0043<b>Fig. 8</b> shows the transmitting and receiving device 10 and the their upstream coupling filter, with the bus coupling is carried to the control line 12th The digital interface 10, in this example, the setpoints for minimale-, maximale- and Emergency lighting brightness (U_NOT, U_MIN, U_MAX) Specified. Furthermore, a provided digital input DAT, about which both the control signals from a central Control unit to the remote ECG reach, as well as the error signals from the decentralized ECGs are transmitted to the central control device. The serial interface enables remote control of the electronic ballast by a digital Command signal or command word. When such a digital signal is an 8-bit data word provided. It is differentiated from the two capacitors C22, C23, then to half of the supply voltage of the control circuit 17 and the transmission and Receiving circuit 10 potential shifted and then a Snubber capacitor C12 digital input DAT interface 10 supplied. This can suppress both the 50 Hz power frequency, and the Input currents of each interface are kept low. FIG. 8b shows a further Configuration of the bus coupling. Here are the two bus lines 12 with the Data input of the digital interface inductively coupled. If ECGs with the FIG. 8a shown coupling filter operated at different phases of the three-phase network, can transient currents flow which affect the data transmission disturbing. These Although equalizing currents can in the circuit shown in Fig. 8b also flow, they but cancel each other because there is no primary-side ground connection exists. A advantageous development of this circuit is shown in FIG. 8c. By using a Secondary winding with center the circuit reverse polarity protection. Applicable is also an optical coupling, however, has this increased power consumption.

0044When control signals are 255 (corresponding to 8 bit) Brightness provided. That too Steuersigal "OFF", represented by the binary word "zero" is possible. By the aforementioned signal off the total EDC added immediately or after a slight Period in a low-power shutdown mode (SLEEP). In him is the minimal Meßstromverbrauch the entire ballast. The inverter 30 and the drive circuit 31 to be shut down and possibly further to lower Time delay, the essential components of the control and regulating circuit 17. Only the receiving circuit of the transmitting and receiving device 10 and the remain monitoring circuit for detecting an emergency operation (NOT) activated. However, the overall circuit performance decreases, below 1 W. To score in such a state a new ball signal a so takes the control and regulation circuit 17 instantly Power up front, the stationary with preheating and ignition (IGN) in the Operating over passes and there is an immediate cessation of the desired Brightness value (DIMM) worried.

0045In addition to controlling the brightness and the emergency mode and the off mode (SLEEP mode) is for the control and regulation circuit 17 also has the task, refer all aforementioned process variables the information to Monitoring and control of the TOE are of importance.

0046These are the voltage monitoring, the emergency operation maintenance and monitoring the fluorescent lamps in terms of filament breakage or gas defect. also through the measured variables, the different operating states of the fluorescent tube, such as ignition, Preheating and steady operating distinguishable. Below are the measured and are summarized on the review relied on process variables:<sl><li>Supply voltage U_ac, U_N.</li><li>Undervoltage / overvoltage U_Nmin, U_nmax.</li><li>Battery voltage U_B.</li><li>Intermediate circuit voltage U₀, U_dc.</li><li>Lamperstrom / operating current I_L1, I_L2.</li><li>Lamp voltage U_L1, U_L2.</li><li>Output voltage U_HF.</li><li>Output current I_HF.</li><li>Wendel current I_W1, I_W2.</li><li>AC generator branch current I_cape,</li></sl>

0047Based on the sizes listed are overvoltage and undervoltage in the DC link and detected in the supply circuit. The control and regulation circuit 17 switches past all the functions when the voltage is too high, and can only return to go function, when the voltage was once again turned on and off.

0048The occurrence of undervoltage - which to a hazardous capacitive operation the inverter leads - is answered so that the drive circuit 31 is blocked. As long as the power supply does not have the necessary voltage to the Heating the filaments to guaranteed and avoid the capacitive operation, takes the control and regulating device 17 no ignition. Only after exceeding a predetermined threshold value, the ignition process is triggered. This happens automatically.

0049A Notbetriebsumschaltung to a predetermined emergency lighting brightness occurs, for example if the above the usual AC supply input Turn-on over the probe 20 and R21, C25 (Fig. 4), a DC voltage U_Nis detected by the control circuit 17th For this a counting logic that at Absence of over- or undershooting of a predetermined threshold value the Emergency operation initiates. This can happen after a pre surrounded dead, the individual, possibly missing, half shafts, bridges.

0050If the normal feeding AC voltage U in a lighting system_ac, U_N from so is an emergency power supply U_BWho recovered from batteries or a generator is placed on the power voltage line. This automatically recognize the TOE.

0051In emergency mode, the brightness of the fluorescent lamps is no longer by the digital preset brightness value DIMM given, but on a decentralized basis by Predeterminable unit trim value via the input U_NOT be predetermined. Should The ECG is the occurrence of this emergency operation in the (SLEEP) sleep mode, ie lamp and inverter switched off, it first performs the normal Ignition (IGN) by to ask afterwards on dic Notbezriebshelligkeit.

0052Detected end of Notbetriebszustandes the ballast goes to the previous state back, this may be the OFF state when the ECG was there before. This but may also be the original brightness value (DIMM), provided that the prior request emergency operation existed.

0053About the acquisition of the spiral flow is to determine if there is either a lamp is not used or one of the two coils is broken. In one of these error cases is the inverter 30 at its maximum frequency f_Max operated, which on the one hand a still flowing heating current to injury if the defective bulb has been exchanged on the other hand the voltage on the defective lamp in the smallest amount possible without sets. This is to comply with the safety regulation VDE important. The inductive part of the series resonant circuit in the output is at the high frequency f mentioned_Max compared to the capacitance of Ignition capacitor C17 so high that the output voltage to a safe level is limited and there is no danger for maintenance staff.

0054At the onset of a functioning lamp without any additional measures after waiting the preheating of the ignition (IGN) initiated.

0055The internal sequence control in control and regulating circuit 17 further limits also the number of start attempts to two and sets (transmits) whenever a Fault but if z. B. missing the lamp when a broken filament or a Gas defect is present, an error signal via the transmitting and receiving means 10 on the bi-directional bus 12 from. This also applies in emergency mode because when the lamp is faulty the emergency can not be complied with.

0056Wiring errors that lead to a short circuit of the discharge path of the lamp, , due to the process signals are then detected when the lamp voltages are monitored for a predetermined minimum value out. It takes a Below this predetermined value, as in the power surge monitoring to a shutdown of the entire ECG.

0057The Zündunwilligkeit of the lamp, for. Example, by gas defect, and by the control Control circuit 17 detected. When the lamp within a predetermined Zündvorgabezeit can not be ignited, that is, when a drop in the voltage on the ignition capacitor C17 does not occur within this period, engages said barrier on.

0058In addition to a complete shutdown and an error message can also be a repetition be awaited, after which a new ignition and Star attempt un ternommen becomes. no detonator Sequence Will this cause, so the control and regulating circuit reacts 17 as in Heizwendelbruch and sets the frequency of the inverter 30 to the maximum value f_Max,

0059When replacing the lamp, which the control and regulating circuit 17 at one Rise of the lamp voltage or a change of Heizwendelstromes recognizes occurs again after re-inserting a new lamp at ignition.

0060For brightness control of fluorescent lamps following may be explained. There is a real brightness control application, as this lamp type irrespective same Air services - at substantially the same lamp efficiency - guaranteed. The istwertbestimmenden variables lamp current, lamp voltage and multiplied with the analog or digital via the transmitting and receiving means 10 remotely predetermined values ​​compared solos. controls the comparison result directly or via a controller, the frequency f of the AC generator 30th If a more accurate gradation desired, then a logarithmic Soli value adjustment carried out. In like manner, an exponential Istwertgewichtung be performed. In addition to the type of lamp independence is also a compensation of the air age, from the existing operating and of the potentially fluctuating mains voltage U_N reached.

0061With the process signal-controlled operating state monitoring, it is also possible for the perform ignition of the lamps to small brightness values, the normally occurring pulse of light can be avoided. The latter is due to the in Output circuit stored by the ignition energy, which then after ignition is abruptly discharged into the air. To suppress or eliminate a rapid ignition recognition - on the change in the lamp voltage U_L1, U_L2 - provided, as well as a rapid reduction of the lamp current after ignition executed. The latter by instantaneous displacement of the inverter output frequency towards higher frequencies. Thereby, the Glow region artificially between the ignition and the stationary gas discharge extended. This would under normal circumstances, a reduction of Lamp life occur. This is like. However, the embodiment avoided, because the extension of the glow phase only for the critical low Brightness values ​​is used. For high brightness values ​​of the current on a will higher level held, whereby the glow phase is shortened. This can about digital set control words and the transmitting and receiving device 10 by software will.

0062In <b>Fig. 9</b> is a brightness timing chart shown in which the brightness of the the ECG-controlled according to FIG. 1 lamp is dependent on time varies. is First maximum brightness provided it is followed by a via the bus line 12 and the Digital interface 10 predetermined shutdown cycle. The brightness is gem. one reduced predetermined slope to zero, then to turn the inverter 30, its driver circuit 31 and main parts of the control IC 17 to the Power savings from. A then the following emergency lighting condition leads - despite system switched off - controlled to a firing and a structure of Lamp brightness to the preset brightness for emergency lighting (NOT). This is via the setpoint input U_NOT changeable for each remote ECG. Likewise, the 9 drawn in FIG. Maximum and minimum brightness (MIN, MAX) a corresponding setpoint set or be calibrated.

0063In FIG. 10 is a program-controlled "soft start" as brightness time chart shown schematically. The ECG 60 is first when switched off (OUT). The "soft start" command now leads either to an automatic slope controlled rise of the lamp brightness - after their ignition - or a program-controlled incremental increase in lamp brightness levels. in the the latter case, from the central control unit 50 from in certain Periods incrementally increasing brightness values ​​sent. The decentralized ECGs follow the needs of almost any delay. In this way, a change-speed-controlled (regulated) rise and fall of distributed light sources possible.