EP2796012A1

EP2796012A1 - Method, operating device and lighting system with integrated lamp rectifier effect detection

Info

Publication number: EP2796012A1
Application number: EP12824791.3A
Authority: EP
Inventors: Hans Auer
Original assignee: Tridonic GmbH and Co KG
Current assignee: Tridonic GmbH and Co KG
Priority date: 2011-12-23
Filing date: 2012-12-21
Publication date: 2014-10-29
Anticipated expiration: 2032-12-21
Also published as: DE102012207002A1; CN104094674B; CN104094674A; EP2796012B1; WO2013090955A1

Abstract

The invention relates to a method for operating at least one light‑emitting means (4), such as a gas discharge lamp, for example, using a clocked circuit (2), wherein a measurement signal which reproduces a first electrical parameter with respect to the light‑emitting means operation is compared with a threshold value (SOCP) in order to identify a fault state for the operation of the light‑emitting means (4), wherein the threshold value (SOCP) can be adjusted depending on a rectifier effect of the light‑emitting means (4).

Description

METHOD, OPERATING DEVICE AND LIGHTING SYSTEM, WITH

DETECTION OF LAMP EFFECT EFFECT

The present invention relates to control gear for lamps, in particular for gas discharge lamps, as well as to a lighting system. It is an object of the invention to efficiently perform a control or a misrecognition in the operation of bulbs.

This object is achieved by the features of the independent claims. The dependent claims further form the central idea of the invention particularly advantageous.

A first aspect of the invention relates to a method for operating at least one luminous means, such as, for example, a gas discharge lamp, starting from a clocked circuit. For detecting a state, in particular an error state, of the operation of the luminous means, a measurement signal which reproduces a first electrical parameter with respect to the luminous means operation is compared with a threshold value. The threshold value can be set as a function of a rectifier effect having the luminous means. A further aspect of the invention relates to a method for operating at least one luminous means, such as. Gas discharge lamp, starting from a clocked circuit. To detect a fault condition of the operation of the bulb is a measurement signal, the one reproduces electrical parameter with respect to the lighting mode, with a. Threshold compared. The threshold value can be set as a function of the DC component of the luminous flux.

Another aspect of the invention relates to a method for operating at least one light source, such as. Gas discharge lamp. A rectifier effect of the

Illuminant is determined such that from a comparison of this rectifier effect reproducing value (Sbase) with a threshold value (SEOL +) an error state (EOL) is derivable ableitba. The determined rectifier effect is taken into account when monitoring another fault condition.

Another aspect of the invention relates to a control circuit, in particular ASIC or microcontroller, which is designed for such a method. Another aspect of the invention relates to an operating device for lighting means, in particular for gas discharge lamps, comprising such

Control circuitry. Another aspect of the invention relates to a lighting system, comprising a control unit and at least one such preferably connected via a bus line such operating device. Another aspect of the invention relates to a circuit for operating a luminous means, such as. Gas discharge lamp, comprising a half-bridge or full bridge circuit for providing a

Supply voltage for the at least one light source, and a control circuit for controlling the operation of the lighting means and / or error detection. In order to detect a fault state of the operation of the luminous means, a measurement signal which reproduces a first electrical parameter with regard to the luminous means operation is compared with a threshold value. The threshold value can be set as a function of a rectifier effect having the luminous means. These aspects can be further developed as follows.

The rectifier effect can be detected by directly or indirectly monitoring a rectifier effect parameter. The rectifier effect parameter can map the voltage dropping at the light source, the luminous flux, the luminous flux impedance and / or the power consumed by the luminous means.

The rectifier effect can be detected by directly or indirectly monitoring a rectifier effect parameter. The rectifier effect parameter can reflect the DC voltage dropping on the lamp or the unbalance of the lamp current. The threshold may be adjustable such that a variation of the rectifier effect parameter results in a corresponding variation of the threshold.

The threshold may be adjustable at each clock or period of the clocked circuit.

A detected change in the rectifier effect parameter may result in the adjustment of the threshold in the next clock of the clocked circuit. Within a cycle, the maximum permissible change of the threshold value can be limited. An error condition can be triggered as soon as the rectifier effect parameter reaches or reaches several times.

The measurement signal can reproduce the current through a switch of the clocked circuit, and be compared to detect an overcurrent with a threshold value.

The threshold can be used to detect a dead reset of a switch of the clocked circuit.

The threshold value can serve to detect a capacitive operation of the luminous means.

Further advantages, characteristics and features of the invention will now be explained with reference to the figures of the accompanying drawings.

Showing:

Figure 1 is a schematic representation of a

First embodiment of the invention or a modification thereof,

Figure 2 shows the time course of

different signals or voltages within the operating device. FIG. 3 shows an exemplary embodiment of the adaptation of the threshold value according to the present invention. FIG. 4 shows a filter according to the invention.

Figure 5, 6, the input and output signals

a filter according to the invention. First of all, a first exemplary embodiment of a measuring circuit for an operating device 1 for at least one lighting means will be explained schematically with reference to FIG. 1.

The AC line voltage is fed via a filter 8 to an AC / DC converter 7. In the AC / DC converter 7, the AC line voltage is converted into a DC voltage and to a higher. Voltage, preferably between 300V and 400V, set. This is accordingly also at the storage capacitor 6. The AC / DC converter 7 may include a rectifier and also an active (PFC) circuit (clocked by a switch controlled by a control unit or formed by a charge pump circuit (Active or Passive Valley Fill)).

An inverter 2, in this case a half-bridge, alternately drives the switches Q1 and Q2, preferably power transistors. This is used to provide a supply voltage for at least one light-emitting element 4. The luminous element or luminous means can be a gas discharge lamp, but also any other type of luminaire, for example an LED or OLED or LED / OLED arrangement. For simplicity, in Fig. 1, the load 5, including the light-emitting element 4 and further necessary for the pre-circuit electrical components, only indicated.

The half-bridge current is detected via a measuring resistor R102 in series with the lower-potential switch Q2 of the half-bridge. The lamp voltage is detected via a resistor divider R104. Both measurement signals are preferably fed via a single pin SDV_lamp a control circuit 3, preferably an ASIC. However, any other form of integrated circuit, such as a microcontroller or hybrid solution, or a conventional (discrete) circuit may be used as an alternative to the ASIC.

The ASIC 3 also controls the AC / DC converter and the clock frequency of the half bridge 2.

The pin SDV_lamp is therefore an addition of the voltages of the lamp voltage resistance divider R104 and the measuring resistor R102. However, it is also possible to use the 2 signals with different terminals of the. Connect ASICs. The ASIC 3 has an internal constant current source A. This supplies the incoming signal with a DC level, so that negative voltages at the pin SDVlamp are avoided. Instead of the internal constant current source A, an external current source, in the simplest case one to a supply voltage (for example the bus voltage or

Low-voltage supply) or an internal or external voltage source can also be used. The signal of the half-bridge current has a regular time interval, preferably one-half

Period length in which it is 0. The reason for this is that during this period, the switch Q2 is open and therefore no half-bridge current is measured. In this period, therefore, only the lamp voltage is applied to the pin SDVi _amp '. This circumstance can be exploited to discriminate the two signals. The signal of the lamp voltage has a sinusoid, which can be sufficiently determined by measuring frequency and amplitude.

Furthermore, it can be exploited to discriminate that lamp voltage error conditions are relatively slow phenomena, while the error conditions in the half-bridge current with a relatively large amplitude and for a short time occur. With the aid of the two signals, as described in more detail below, an overcurrent, for example at throttle saturation in the lamp ignition process or an overcurrent during lamp operation, can be determined. Furthermore, a capacitive operation of the lamp and an EOL effect (end of lamp life) of the lamp can be detected.

The attenuation of the AC component of the lamp voltage takes place in the circuit of FIG. 1, regardless of their DC component. Preferably, the AC component is attenuated more than the DC component. This is achieved by the parallel connection of capacitor C10X and resistor R102. This parallel connection has a strong damping effect on higher frequencies. The capacitor C10X serves as a filter for the AC component. Thus, the DC component is less damped relative to the AC component.

This provides the advantage that both values can be damped suitable for the ASIC areas _^. This is necessary because the voltage spikes of the AC component in the firing process are many times higher than the DC component whose DC offset is used to identify an EOL. If the capacitor C10X has a sufficiently large value, the high-frequency

Wechselspannungsariteil the lamp voltage are filtered out, so that the detected signal at the input SDV _Lamp is composed of the DC voltage component of the lamp voltage and the half-bridge current. Thus, during the phase in which no half-bridge current is detected, the DC component of the lamp voltage can be measured, while in the phase in which a half-bridge current flows, the half-bridge current is detected, taking into account the determined DC voltage component of the lamp voltage.

The AC signal of the half-bridge current can be used, for example, to identify a saturation of the throttle as well as to detect an overcurrent, a capacitive operation or for preheat control.

In the ignition detection, for example, additionally monitors whether the throttle is no longer in saturation. It can also be an ignition control, in which the throttle is driven to saturation. Ignition of an ignition-deficient or defective lamp will cause the circuit to saturate as the frequency is pushed very close to resonance). In case of saturation can at least one half-bridge switch is opened earlier, but preferably the next switching clock is initiated with the previous switch-on time. The omission of the saturation, or a high ignition current, can also be used as an ignition detection signal

Further advantageous evaluation possibilities of the current signal are shown below. For this purpose, the half-bridge current and / or the lamp current can be detected. So that the lamp current 'can be used for a measurement during preheating, it requires a special pre-circuit, so that even when preheating this lamp current can be measured. The lamp current signal can be measured at the point "lamp voltage". The half-bridge current can be detected via the measuring voltage at the half-bridge shunt R101:

- can be a half-bridge current measurement and / or Lampenstromme ^'Ssung to "closed loop" control (ie, control with, closed loop) of the

Lamp power or the preheating energy can be used.

- In addition, a measurement to detect the lamp filaments based on the transmitted preheating, or the filament are performed. Thus, a lamp detection can be performed.

A "relamp" detection can be carried out, that is, whether a (new) lamp has been used, namely on the behavior of the output circuit

- A half-bridge current measurement and / or lamp current measurement, can be used for fault detection: It may increase the risk of saturation be reduced during ignition or too high a current even during operation.

- In addition, protection against a capacitive lamp operation and / or overload of the switch can be achieved at power.

- A half-bridge current measurement and / or lamp current measurement can be used to control the current.

- The half-bridge current can also be used to control the heating energy, in particular the preheating energy.

- The lamp current can be used to control the lamp power or to control the preheat energy.

- It can also saturate (especially during the

Ignition) or an overvoltage in the load circuit can be detected on the basis of the voltage measurement.

Further advantageous applications of the voltage evaluation are shown below.

- A voltage measurement can be used for the end-of-life detection of the lamp.

- A lamp voltage measurement can be performed

Detection of the heating wire can be carried out, for example in the presence of an additional DC path from the bus voltage via a helix. As a result, it can also be recognized whether a lamp is used at all.

A "relamp" detection can be performed, i.e. a new lamp has been inserted.

- It can be detected a lamp ignition. It should be noted that any

Evaluation possibilities of the current measurement with those of the voltage measurement can be combined. To start a lamp, the heating coils of the lamp 4 are first preheated. For this purpose, the half-bridge 2 generates an AC voltage which is above the resonant frequency of the resonant circuit. The resulting voltage is too low to cause the ignition of the lamp 4. The pin SDVI _Lamp may be located at that time in the standby state, if any of the measurements described above is claimed, such as, a lamp filament detection or Vorheizregelung.

At the end of the preheating time, the ignition of the lamp 4 is achieved by gradually increasing the on-time of the two switches Q1 and Q2 of the inverter. Accordingly, the operating frequency of the inverter is reduced. .

In the preheating phase, a small current flows through the lamp. The DC offset caused by the EOL effect is very low. This can therefore be ignored here. Therefore, no compensation of a DC offset by an internal DC power source A is necessary here. Thus, it is possible to turn on the internal power source A only after the ignition of the lamp with a preset value. The internal current source A can also be realized as a stepwise switchable current source or as a parallel connection of two current sources. As a result, different currents to compensate for a DC offset can be impressed by the internal power source A and Thus, during the different phases of operation different compensations or

Abschaltempfindlichkeiten be achieved. Preferably, during the ignition, a lower current can be set for the internal current source A, so that a lower sensitivity can be set according to the expected high voltages.

The detection of errors such as the detection of the EOL effect can be activated depending on the operating state of the lamp or the circuit.

The following is an example of a method for avoiding overcurrent in lamp ignition.

After starting the process in a first step, the heating coils are preheated. In the next step, switch Q1 of the inverter is closed. Switch Q2 is open at this time. After a time t _R , the switch Ql is opened again. At t _R , it is preferably half the period of the current operating frequency of the inverter, but it may also be a shorter period of time.

In the following step, the switch Q2 is closed. There may be a delay time t _D between the opening of the switch Q 1 and the closing of the switch Q 2.

In the next step, the signal applied to .Pin SDV _{lamp is} measured. If it is above a threshold value iamp peak (pk), the lamp is supplied with an excessively high current. However, it is also conceivable, an inadmissible high current only when the threshold has been exceeded several times, for example five times. In addition, the increase in the current can also be assessed and an inadmissibly high rise can be used as an additional assessment criterion.

When the threshold value is determined, the signal to be analyzed in the ASIC must always take into account the signal of the lamp replacement voltage. For this purpose, the signal of the lamp voltage from the ASIC must be compensated analogously without delay. By means of the time window in which switch Q2 is opened and, accordingly, the measured half-bridge current is zero, the lamp voltage signal can be determined.

In a smoothing or damping of

AC component of the lamp voltage through a capacitor (see Fig. L), it may be sufficient that only the DC component of the lamp voltage must be considered.

For returning the half-bridge current to permissible ranges, the switch Q2 is now opened again immediately. This is equivalent to an increase in the current switching frequency. The actual operating frequency of the inverter is not changed. The process is instead repeated with keeping the current operating frequency, preferably after a dead time, by a return to the step of closing the switch Ql. However, it is also possible to return the half-bridge current to allowable ranges reach by increasing the operating frequency of the inverter in the short term.

The voltage applied to pin SEV _lamp signal is below a threshold value Vi _amp _peak (pk) is located, the switch Q2 is again opened after the time t _R. However, the switch Q2 can also be opened again in a time t <t _R. In a subsequent step, the duty cycle t _{R is} increased. Thus, the operating frequency of the inverter is reduced.

The process is repeated several times in succession. There may be a delay time t _D between the steps of opening and closing the switches.

During normal operation of the lamp, the inadmissible state may occur that the lamp is operated capacitively. In this state, a current flows through the switch when switching on. This can destroy the switch. Furthermore, in capacitive operation, the regulation of the lamp by the ASIC no longer works.

The following example shows a method of avoiding capacitive operation of the lamp. To identify a capacitive operation, a gradient measurement is made here between the phase of the lamp voltage and the half-bridge current. (Instead of the lamp voltage, it is also possible to monitor another voltage in the load circuit, for example the voltage across the choke or via a transformer, if present). After a successful ignition, the lamp is in normal operation. At least two measurements are now taken at successive times on the SDVi _amp pin. The measurements are samples. The measurements are taken at a time when switch Q2 has just not been opened.

The difference of the at least 2 measurements is then calculated.

If the subsequent sample is lower than the previous one, then there is an inductive operation of the lamp. This operation is permissible.

The measuring process is repeated several times. However, the possibility also exists after a time interval, or only after the change of parameters, e.g. the lamp dimming, make another measurement.

If the subsequent sample value is higher than the previous one, then there is a capacitive operation of the lamp. This operation is prohibited.

However, it is also conceivable to detect an impermissibly capacitive operation only when the subsequent sample value has been higher than the previous one several times, for example five times in succession.

Then the switch Q2 is opened.

After a dead time, the switch Ql is closed again. The dead time is preferably a predetermined value, but it is also conceivable to use an adaptive method for determining the dead time. For example, an extension of the dead time would be possible with a single or renewed occurrence of a capacitive operation. The dead time can also be adjusted by measuring and checking the half-bridge current shortly before switching on the switch Q2 (ie while a current is already flowing through the free-wheeling diode from the switch Q2). With an impermissible value for the half-bridge current, the dead time can be increased and thus the switch Q2 can be protected from an overcurrent or an overload.

After closing the switch Ql jumps back and the measuring process is repeated.

Another method for avoiding capacitive operation of the lamp is explained below. To identify a capacitive operation, a differential measurement of absolute values is made here.

Ah place the difference measurement but also an absolute value detection is conceivable. Here, a comparison of the current value is made before turning off switch Q2 with a threshold.

After a successful ignition, the lamp is in normal operation. A measurement Sl is made immediately before switch Q2 is turned off at pin SDVi _arap .

Another measurement S2 is made immediately after switching on switch Ql.

Then the threshold is compared with the difference Sl - S2. If the difference Sl - S2 is greater than the threshold, then there is an inductive operation of the lamp. This operation is permissible. It will jump back and the measurement process repeated. However, it is also possible to make a measurement again only after a time interval, or only after the change of parameters, eg the lamp dimming.

If the difference Sl - S2 is smaller than the threshold, then there is a capacitive operation of the lamp. This operation is prohibited. However, it is also conceivable to detect an impermissibly capacitive operation only when the difference has been smaller than the threshold value several times, for example five times in succession.

The driving frequency of the half-bridge is subsequently increased. As a result, the lamp operation returns to the inductive branch of the resonance curve.

If an inadmissible capacitive operation is detected beyond a predetermined number of measurements, the lamp is turned off.

For this purpose, a counter x can be used, which is increased by one.

The value of the counter x is compared with a reference value.

If x ^ Χ, -ax, the lamp is switched off. In this case, the counter x can be reset to 0. Instead of an immediate shutdown, any other measure is conceivable, for example, a signal that warns of a capacitive operation. It should be noted that, of course, the approaches of the above examples can be reversed. This means that in a gradient measurement also a frequency increase of the half-bridge, and in an absolute value measurement, an early opening of switch 2 is possible. Other combinations of features from the above examples are conceivable.

After a successful ignition of the lamp, the charge in capacitor C1Ö1 slowly becomes smaller. This charge was caused by a high half-bridge current during the ignition phase. Charge the internal DC power source and the DC component of the lamp voltage, however, due to an EOL (End of Lamp Life) - ^one effect ^"the capacitor C101 at the same time again in this way the load stabilizes at a certain level..

By means of a measurement before or during the switching off of the switch Q1, the DC component of the lamp voltage can be easily monitored.

FIG. 2 shows the time profile of different signals or voltages within the operating device 1.

The signal Vgs / Ql indicates the gate-source voltage or the control voltage of the higher-potential switch Ql of the inverter 2. The signal Vgs / Q2 is the gate-source voltage or the control voltage of the potential-low Switch Q2. Both switches are turned on and off periodically. In each period TP, each switch Q1, Q2 is turned on once. The higher-potential switch Q1 is turned on at a time TO, T4 and turned off again at a later time Tl. The potential-low switch Q2 is turned on at a time T2 and turned off again at a later time T3. Between switching off one of the switches and turning on the other switch, there is preferably a delay time T2-T1 and T4-T3. The control voltages Vgs / Ql, Vgs / Q2 for the switches are preferably PWM signals.

With regard to the low-potential switch Q2, the voltage Vds / Q2 between drain and source is also shown in FIG. When switch Q2 is on, this voltage Vds / Q2 is at a low voltage level, preferably zero. After switching off the switch Q2, this voltage Vds / Q2 rises to a constant value and, after switching off the higher-potential switch Ql, it again drops to the low voltage level.

The signal SDEOL corresponds to the signal SDV _Lamp described above, which is present at the pin of ASIC and which represents the measurement of the half-bridge current and the lamp voltage.

According to the invention, as described above, a rectifier effect can be deduced. In particular, this effect is detected on the basis of the signal SDEOL, for example if the DC component of the lamp voltage is higher than a first threshold value SEOL +. Alternatively or additionally, a rectifier effect is detected if the DC component of the lamp voltage is smaller than a second threshold value SEOL-. The rectifier effect can occur, for example, on older gas discharge lamps or fluorescent lamps and lead to an overload of the operating device 1. Because of the uneven emission surfaces of the two

Lamp electrodes may then be higher in one direction than in the other over the gas discharge path of the gas discharge lamp lamp current flowing in one direction. The fluorescent lamp then acts in a similar way to a rectifier, preferentially passing the lamp current in one direction while being less well transmitted in the opposite direction.

A slower occurring rectifier effect is detected according to the invention. This is done e.g. by means of the signal SDEOL, in which the value of this signal SDEOL is detected during the switch-off time of the higher-potential switch Q1 or during the switch-on time of the low-potential switch Q2. The only measured DC component of the signal SDEOL indeed comes from the lamp voltage during this period. If the measured value of the DC lamp voltage is not between the two prescribed threshold values SEOL + and SEOL-, an inadmissible rectifier effect is detected and appropriate measures are taken.

Alternatively, the rectifier effect can also be recognized by the fact that asymmetries in the lamp current occur. An excessive asymmetry would then lead to a fault condition. As a monitoring signal so can also serve the lamp current. According to one exemplary embodiment of the invention, the measurement of the lamp current takes place with the aid of the above-described signal SDVI _lamp . This signal SDVI _lamp is connected to a pin of the ASIC present, to which the measurement of the half-bridge current, the lamp voltage and the lamp current are supplied. Alternatively, a measuring resistor (not shown) may be provided for measuring the lamp current.

Alternatively, a current shift occurring between individual lamp branches due to the rectifier effect can also be detected by evaluating the impedance or the power of the lamp 4, the impedance or the power being measured in a known manner.

When the potential-low switch Q2 is switched on, the above-described method for avoiding overcurrent, which has already been described above, is carried out with the aid of the signal SDEOL. During this period, the lamp current is compared with a threshold for the lamp current SOCP. If the measured lamp current exceeds this threshold SOCP, an error condition OCP (Overcurrent Protection) is triggered, i. too high a current flows through the resistor in series with the lower-potential switch of the half-bridge. Preferably, the above-described corresponding measures are to be taken.

According to the invention, this threshold value for the lamp current SOCP is set as a function of a detected rectifier effect. In the embodiment of FIG. 2, the DC component of the lamp voltage Sbase is taken into account when setting the threshold value for the lamp current SOCP. If the DC lamp voltage Sbase increases, the control circuit 3 causes the threshold value for the lamp current SOCP to increase.

In a similar manner, according to the invention, the threshold value SCCD for the error state as well. one capacitive state, and the threshold for the switching of the switches of the half-bridge inverter at zero voltage state adjusted according to the DC lamp voltage.

3 shows an exemplary embodiment of the adaptation of the threshold value SOCP for the detection of an error state due to an excessively high current through the potential-low switch Q2. The low-potential switch Q2 of the half-bridge is turned on and off once per period TP. A period can also be called a clock.

In the first period between 0 and TP, the control circuit 3 measures a DC lamp current of 0. At the same time, the control circuit 3 performs overcurrent monitoring. For this purpose, as already described, it compares the current through the switch Q2 with the set threshold SOCP / 0. Since no DC lamp voltage has been measured, the threshold for detecting an overcurrent in the second period remains the same.

In this second period between TP and 2TP, a DC lamp voltage Δ1 is measured. This value is taken into account according to the invention for adapting the threshold value SOCP. Thus, in the third period between 2TP and 3TP, the threshold SOCP is increased accordingly, preferably to SOCP / 0 + Δ2. It can be seen from FIG. 3 that the adaptation of the threshold value SOCP preferably already takes place one period after the detection of a DC lamp voltage. As soon as a variation of the DC lamp voltage is measured by the control circuit 3, in the next clock or in the next Period of threshold SOCP adjusted and recalculated.

A variation Δ1 in the DC lamp voltage causes the new threshold value to be changed by the value Δ2. According to one embodiment, the threshold increases or decreases in accordance with the variation of the DC lamp voltage. In this case, Δ2 = Δ1. Alternatively, the adjustment of the threshold value may be made proportional to the variation Δ1 of the DC lamp voltage: Δ2 = k-ΔΙ, where k is a preferably positive value. Preferably, the variation Δ2 of the threshold SOCP is a function of the variation Δ1 of the DC lamp voltage.

The invention thus preferably proposes to detect a multiplicity of possible fault states during operation of a gas discharge lamp at a pin of an ASIC. The detection on different pins is also provided. These error conditions are, as already mentioned:

OCP (Overcurrent Protection), i. too high current through the shunt in series to the lower potential

Switch of the half bridge,

EOL (End of Lifetime), rectifier effect of the lamp,

CCD (Capacitive Current Detection), Capacitive Current or Capacitive Operation,

Saturation It would also be conceivable to switch the switch of the

Half-bridge inverter to detect at zero voltage state. Meanwhile, the thresholds for OCP and CCD as well as optional other errors such as saturation or switching at zero voltage setting and adaptive are set. For this purpose, the reference value (SOCP, SCCD) in each cycle, in which the higher-potential switch Ql is turned on, new

set.

Upon manipulation of the voltage on the sense pin during the period during which higher potential switch Q1 is turned on, the corresponding thresholds (SOCP, SCCD) may be changed in the subsequent cycle.

According to the invention, therefore, a shutdown due to an OCP, CCD, and / or another fault condition is dependent on a DC lamp voltage. For example, the shutdown can be done only at a higher (SOCP / 0 + Δ2) or even at a much lower switch current (OCP state).

The DC lamp voltage, also called baseline or zero line in FIG. 2, or this level is at the same time also the level which is set in relation to the error states EOL with the non-relative but absolute threshold values SEOL +, SEOL-. This means that the corresponding error states are reached when the baseline level reaches the corresponding absolutely predefined switch-off thresholds SEOL +, SEOL-. However, interference can also be coupled in, for example by timing other switches in the operating device, PFC switches, heating switches, etc. A further development of the invention thus proposes such short-term disturbances in the adaptation of the various Threshold values SOCP, SCCD should be ignored or not taken into account as far as possible. According to the invention, such disturbances are taken into account only stepwise or clockwise to a certain extent in which, in the course of the adaptation, a maximum variation of a threshold per cycle is determined.

4 shows a corresponding exemplary embodiment of a filter 170. With each switching cycle of the half-bridge, the threshold values SOCP, SCCD are adaptively changed in such a way that the coupling of the disturbances due to misinterpretation can be prevented from leading to premature switching off of the half-bridge or of the operating device.

The filter 170 prevents such abrupt changes in the DC lamp voltage from leading to undesired error conditions OCP, CCD. The detected signal of the pin SDV lamp is supplied to the filter, for example via a low-pass filter. Optionally, an analog-to-digital converter (174) may detect and relay the signal. An input comparator 171 feeds an increment-decrement counter 172. A sampling unit 173 is preferably clocked with the clocked inverter 2, e.g. at a period of 50 ps. The sampling unit 173 provides the adaptation for the threshold values SOCP, SCCD to the output of the filter 170.

The input and output signals INPUT, OUTPUT of the filter 170 are shown in Figs. The input signal INPUT preferably corresponds to the detected DC component of the lamp voltage or outputs this value again. The output signal OUTPUT corresponds to the adjusted threshold value SOCP, SCCD or Variation of the threshold Δ2 or reflects these values.

In FIG. 5, the input signal INPUT takes the value 20 at t-0 s and then remains constant until the time t = 0.010 s. At this time, the input signal INPUT rises to the value 30.

According to the invention, the maximum variation of the threshold value SOCP, SCCD is limited for each cycle. The filter 170 limits e.g. the variation to the value 1 for each cycle. In other words, within 50 με, which corresponds to the cycle of the inverter, the threshold values can increase or decrease by a maximum of 1. The values for the input and output signals indicated in FIGS. 5, 6 are preferably voltages in volts.

At the exit, after only 0.001 seconds, i. after 20 cycles, the input value of 20 is taken into account.

In FIG. 6, however, an input signal is shown which remains nearly constant from t = 0 to t = 0.020 s. Only at t = 0.010 s is there a short-term spike increase in the DC lamp voltage, e.g. due to a disturbance.

The value of the output signal rises rapidly, ie already after 0.0025 s, to the predetermined input value of 50. Thereafter, the output signal and thus also the threshold value SOCP, SCCD remain stable at the desired value. The erratic disturbance at t = 0.010 merely results in the output signal being increased by the maximum permissible value 1 for two cycles. After two cycles If the fault is over and the input signal drops back to the value 50. Accordingly, the output falls within two additional cycles to the desired value. The short-term disturbance thus has no negative influence on the error detection OCP, CCD.

The adaptive tracking of the threshold values SOCP, SCCD proposed by the invention is particularly advantageous in a state in which a certain EOL contribution is already provided, but the EOL switch-off thresholds SEOL +, SEOL- have not yet been reached.

The DC offset of the lamp voltage may be subject to certain fluctuations. However, according to the present invention, it is contemplated that these variations adaptively result in the corresponding shift of the turn-off threshold SOCP, SCCD in the next cycle.

Additionally or alternatively, also a possible DC offset at the input SDV lamp can be determined already in the phase before the ignition of the lamp and then taken into account in the operation of the lamp, ie after ignition, in the evaluations of the measurements and when setting the thresholds ,

List of reference numbers:

1 operating device

2 inverters

3 control circuit with internal DC power source

4 light element

5 load

6 storage capacitor

7 AC / DC converters

8 filters

Ql potential higher switch (HS = High Side)

Q2 · low-potential switch (LS = low side)

R102 Measuring resistor in series with the half bridge to

Measurement of the half-bridge current

R104 Voltage divider resistor parallel to

Luminous element for measuring the lamp voltage SDV _Lamp Pin of the ASIC to which the measurement of the

Half-bridge current and the lamp voltage can be supplied

SDVI _Lamp Pin of the ASIC to which the measurement of the

Half-bridge current, the lamp voltage and the

Lamp current can be supplied

A internal DC power source of the ASIC

R101 measuring resistor ("shunt")

C101 AC filter

R107 Measuring resistor in series with the light element for

Measurement of the lamp current

C62 coupling capacitor

L60 series resonance resonant circuit C63 Capacitor of series resonant circuit

I _S half-bridge current

ILamp lamp current

VLamp lamp voltage

Claims

Claims: 1. Method for operating at least one luminous means (4), such as, for example, a gas discharge lamp, starting from a clocked circuit (2), wherein

for detecting a state, in particular an error state, of the luminous means operation, a measurement signal, which reproduces a first electrical parameter with respect to the light-emitting operation, is compared with a threshold value (SOCP),

the threshold (SOCP) depends on a

Illuminant (4) having rectifier effect

is adjustable.

2. The method according to claim 1,

wherein the rectifier effect is detected by direct or indirect monitoring of a rectifier effect parameter, and

the rectifier effect parameter the voltage dropping at the light source (4), the light source current, the

Illuminant impedance and / or from the light source (4) related power maps.

3. The method according to claim 1,

the rectifier effect parameter reproduces the DC voltage (Sbase) dropping at the light source (4) or the asymmetry of the lamp current.

4. The method according to any one of claims 2 to 3, wherein the threshold value (SOCP) is adjustable such that a variation (Δ1) of the rectifier effect parameter causes a corresponding variation (Δ2) of the

Threshold (SOCP).

5. The method according to any one of claims 2 to 4,

wherein the threshold value (SOCP) is adjustable at every clock or period of the clocked circuit (2).

6. The method according to any one of claims 2 to 5,

wherein a detected change of the rectifier effect parameter in the next clock of the clocked circuit (2) results in the adjustment of the threshold value (SOCP).

7. The method according to any one of claims 2 to 6,

wherein, within one clock, the maximum change in threshold (SOCP) is limited.

8. The method according to any one of claims 2 to 7,

an error condition (EOL) is triggered as soon as the rectifier effect parameter (Sbase) reaches or reaches a threshold value (SEOL +, SEOL-) several times.

9. The method according to any one of the preceding claims,

wherein the measurement signal represents the current through a switch (Q2) of the clocked circuit (2) and is compared with a threshold value (SOCP) for detecting an overcurrent (OCP).

10. The method according to any one of the preceding claims,

wherein the threshold value is for detecting a voltage-free reconnection of a switch of the clocked circuit.

11. The method according to any one of the preceding claims,

wherein the threshold value (SCCD) serves to detect a capacitive operation of the luminous means (4).

12. A method for operating at least one light source (4), such as. Gas discharge lamp, starting from a clocked circuit (2), wherein

to detect a fault condition of the operation of the

Illuminant (4) a measurement signal representing an electrical parameter with respect to the operation of the illuminant, with a threshold value (SOCP, SCCD) is compared, wherein the threshold value is adjustable depending on a DC component of the lamp voltage (Sbase).

13. A method for operating at least one light source (4), such as. Gas discharge lamp, wherein

a rectifier effect of the luminous means 4 is determined in such a way that an error state (EOL) can be derived from a comparison of a value (Sbase) with a threshold value (SEOL +) representing this rectifier effect,

- The determined rectifier effect is taken into account when monitoring another fault condition.

14. Control circuit (3), in particular ASIC or

Microcontroller designed for a method according to one of the preceding claims.

15. operating device for illuminants, in particular for gas discharge lamps,

comprising a control circuit according to claim 14.

16. lighting system, comprising a control unit and at least one preferably connected via a bus line

Operating device according to claim 15.

17. Circuit (1) for operating a luminous means (4), such as, for example, gas discharge lamp,

including

a half-bridge or full-bridge circuit (2) for providing a supply voltage for the

at least one lighting means (4), and

a control circuit (3) for controlling the operation of the lighting means (4) and / or fault detection,

wherein a detection signal representing a first electrical parameter with respect to the light-emitting operation is compared with a threshold value (SOCP) for detecting an error state of operation of the lighting means (4), and

the threshold (SOCP) depends on one

Illuminant (4) having rectifier effect

is adjustable.