EP2088837B1 - Method for operating a UV lamp - Google Patents

Abstract

The method involves presetting a lamp reference power without exceeding additional parameter after completion of preset burning in phases such that an operating state of a UV-gas discharge lamp (8) is obtained. Desired lamp power for successive operating phases is adjusted by varying the frequency and the voltage. The presetting of the lamp reference power and the adjustment of the desired lamp power are controlled by an electronic control (14). Desired data of a superior control is provided in form of a peripheral interface for further process development.

Description

The invention relates to a device for operating a UV lamp according to claim 1.

Powerful UV lamps are used as UV lamps for a variety of purposes. For example, for drying and / or curing liquids, gels, adhesives, paints and paints. The UV radiation causes a chemical reaction. For example, DNA strands can also be separated. In general, the UV irradiation with such lamps can support chemical processes, as well as the exposure of photoactive materials (eg, lithography), or fluorescence excitation of various substances (eg, banknote validators). This technique is mainly used for UV curable materials such as curable polymers, paints and adhesives.

Such UV lamps are designed according to the prior art as gas discharge lamps and are electrically powered and driven with appropriately suitable ballasts. The characteristic of such powerful gas discharges requires the operation to comply with certain measures. In the known operation, the lamp is operated on the AC mains and connected in series with the lamp, a throttle for limiting the current. In addition, to start the lamp measures must be taken to ignite the gas discharge, such as the application of a voltage pulse to the discharge path to initiate the discharge. This is a voltage which is excessive compared with the burning voltage and which is applied for a short time and is no longer necessary after ignition has taken place. After ignition, the impedance of the discharge path is lower and the lamp continues to burn with the aid of the applied AC voltage.

According to the state of the art, conventional ballasts (CCG), for example traditional throttle controls, as well as increasingly, special electronic ballasts (EVG) are used for the control of a UV lamp. The ballasts must, however, always have the flat characteristic of a UV lamp - the burning voltage is almost independent of the current - can provide.

The conventional ballasts (KVG) use the property of the choke and are therefore connected in series with the 400V AC grid. For the adjustment of the lamp power single additional chokes are switched to it. This means, for example, to drive with the switch open at 50% power, with the switch closed at 100% power. In addition to the ballast, a ignitor is needed to start the spotlight. In addition, a compensation of the image stream is necessary.

This known arrangement has the disadvantage that a stepless adjustment of the lamp power is only very limited possible. Therefore, in the past various modifications have been made to the power adjustment such. B. Transducer operation with or without stray field transformer or step-up transformer.

Conventional ballasts are large and heavy chokes, transducers and transformers with iron cores and due to the low frequency of 50Hz, components with high inductance values. High stray fields and thermal dependence of the electrical properties are further disadvantages. Each KVG unbalanced loads the three-phase network.

• Symmetrische Netzbelastung,
• Einstellbarkeit der Lampenleistung,
• die Vorschaltgeräte kleiner und leichter zu machen,
• automatische Anpassung an die verschiedenen AC-Netze,
• die schnelle Pulsbarkeit der Leistung im Millisekunden-Bereich ermöglicht die Anpassung auch an schnelle diskontinuierliche Prozesse und führt somit zu Energieersparnis und geringerer Aufwärmung des Substrats bzw. des Werkstücks.

In order to improve the disadvantages of CCGs, electronic ballasts have emerged with the aim of achieving the following improvements:

• Balanced network load,
• Adjustability of the lamp power,
• make the ballasts smaller and lighter,
• automatic adaptation to the various AC networks,
• The fast pulsability of the power in the millisecond range allows the adaptation to fast discontinuous processes and thus leads to energy savings and less heating of the substrate or the workpiece.

Such electronic ballasts are usually constructed as a full-bridge inverter. The Funktionsprinzipe the electronic ballasts can in those with low-frequency rectangular operation (eg, with 250 Hz) and those with higher-frequency throttle operation (eg 100 kHz) are divided. For the ignition of the gas discharge of a UV lamp, on the one hand, the superposition principle with the help of an external igniter, and on the other hand can be divided into one in which a resonant UC resonant circuit is applied. In both cases, however, additional components are required, which increase the effort.

In the EP 0 741 503 A1 For example, a circuit arrangement and a method for operating a high-pressure discharge lamp is described, in which operation should also be possible with a power lower than the rated power. It is proposed to operate the lamp for the rated power with a conventional ballast with low-frequency energy, but to switch to a higher-frequency electronic ballast for the operation with reduced power. Thus, this arrangement requires two ballasts and is therefore expensive. In addition, the power can only be set in two stages, ie not continuously.

In these known arrangements and methods for operating a UV lamp, the individual components must be adapted in each case to the operating parameters and to the different lamp types, so that a standardization of such ballasts is only possible to a limited extent. Another disadvantage is that the known methods for driving a lamp to achieve the longest possible life of the lamp are not optimal, and also the aging effect of the lamp, which is associated with a decrease in the efficiency of the UV lamp is not taken into account, and generally can not be taken into account. In addition, it is difficult to realize compact lamp systems which independently enable lamp operation but can also be integrated directly into higher-level process controllers.

The state of the art attributable to Art. 54 (3) WO 2008/055366 as well as the US-A-2002/145886 constitute the generic term from which the present invention is based, and both documents are concerned with a method of operating a UV lamp.

The EP-0 689 373 envisages the use of an interface in a circuit for operating a UV lamp.

The synchronization by its own control is about in the GB 2 274 430 mentioned for a printing machine, which indicates a synchronization of the switching of the UV lamp from a normal operation in a stand-by mode and the operation of the shutter as possible, to which separate control means are provided, which will not be discussed in detail. About a control device to a possible, but not addressed, synchronization is missing any hint in the US 5,343,629 or in the JP 08-072270 ,

The present invention is therefore based on the object to avoid the disadvantages of the prior art.

In particular, the object of the invention is to enable a simplified and economical operation of the UV lamp using largely standardized components, since the invention comprises the essential operating elements including the control for the operation of the lamp in a single system, and simply a higher level Process control is einbindbar. Furthermore, the operational reliability and service life of the lamp should be increased by the invention, wherein the operating values are reproducible with high accuracy. In addition, the arrangement for operating the UV lamp and the method itself should be easy and economical to implement.

This object is achieved by a device having the features of claim 1.

This method allows a very smooth operation of the lamp and a very flexible process management with complete integration of all necessary conditions for safe operation in a single arrangement thanks to the voltage and frequency control of the inverter. It also makes it possible to operate different lamp types and outputs with the same concept. A scaling of the performance classes with standard components is thus given in a very large area.

The ignition process can with a separate ignition arrangement or with an additional ignitor by briefly applying and superimposing a voltage over the voltage boosted voltage as a voltage pulse with sufficient voltage-time surface be initiated. The method with control of the frequency and / or the output voltage of the inverter makes it possible to completely dispense with such an additional ignitor. As a result, the arrangement is greatly simplified and allows a gentle ignition of the lamp. Advantageously, the current-limiting means consist of a series-connected inductor, which further simplifies the structure of the arrangement and additionally allows a voltage increase on the lamp to ignite in a simple manner, if for the ignition of the electronic control in each case the frequency and the voltage according to predetermined Values increased until the ignition occurs. The ignition process can be easily monitored, preferably by measuring the voltage dip and / or the current increase on the lamp or in the supply lines or on the inverter, or with a light sensor. If the ignition is unsuccessful, another ignition process or several of these can be initiated automatically, as required, until a safe and stable operating state is achieved. The operating power of the lamp is set or regulated with the frequency according to the higher specification or according to a profile with the control. In addition, a movable shutter is operated as a so-called shutter in front of the lamp according to the process specifications by means of the controller. Such a shutter can be opened, for example, for the UV radiation of the lamp when the baking phase is over and a stable operation is ensured, and it can be selectively closed again after delivery of a radiation dose to the workpiece, sheet or other object to be machined. The controller itself advantageously has an interface, which makes it possible to connect the system to a further, external or higher-level process controller. This makes it possible to modularly build the system as a stand-alone unit, increasing the flexibility of delivery and reducing the cost of storage, and reliably operate and monitor the UV lamp with all its operating parameters.

Fig. 1

schematisch eine bevorzugte Schaltungsanordnung des Speisungs- und Steuerungssystems für den Betrieb von UV-Gasentladungslampen;

Fig. 2

eine Spannungskennlinie für das Verfahren zum Betrieb einer UV-Lampe mit bevorzugter Zündung mittels des Spannungs-/Frequenz- Zündverfahrens durch den gesteuerten Umrichter;

Fig. 3

eine Frequenzkennlinie für das Verfahren zum Betrieb einer UV-Lampe mit bevorzugter Zündung mittels des Spannungs-/Frequenz-Zündverfahrens durch den gesteuerten Umrichter mit den der Kennlinie nach Fig. 2 entspre- chenden Schritten;

Fig. 4

eine der Fig. 2 entsprechende Darstellung, aber mit einem separaten, externen Zündgerät;

Fig. 5

eine der Fig. 3 entsprechende Darstellung, aber mit einem separaten, externen Zündgerät;

Fig. 6

schematisch eine Schaltungsanordnung des Speisungs- und Steuerungssystems für den Betrieb von UV-Gasentladungslampen mit einem bevorzugten separaten Zündgerät als Zündhilfe; und die

Fig. 7

im Detail eine bevorzugte Schaltungsanordnung für eine Zündhilfenbeschaltung eines Zündgerätes entsprechend der Anordnung nach Fig. 6.

Further details and features of the invention will become apparent with reference to the following description of schematically illustrated in the drawings embodiments. Show it:

Fig. 1

schematically a preferred circuit arrangement of the supply and control system for the operation of UV gas discharge lamps;

Fig. 2

a voltage characteristic for the method of operating a UV lamp with preferential ignition by means of the voltage / frequency ignition method by the controlled inverter;

Fig. 3

a frequency characteristic for the method for operating a UV lamp with preferential ignition by means of the voltage / frequency ignition method by the controlled inverter with the characteristic according to Fig. 2 corresponding steps;

Fig. 4

one of the Fig. 2 corresponding representation, but with a separate, external ignitor;

Fig. 5

one of the Fig. 3 corresponding representation, but with a separate, external ignitor;

Fig. 6

schematically a circuit arrangement of the supply and control system for the operation of UV gas discharge lamps with a preferred separate ignitor as ignition aid; and the

Fig. 7

in detail a preferred circuit arrangement for a Zündhilfenbeschaltung an igniter according to the arrangement according to Fig. 6 ,

The Fig. 1 is divided into two parts, the two parts are thought to be connected to each other via the lines 17, 18, 11 'and 20'. In this preferred arrangement according to Fig. 1 For the operation of a UV lamp 8, a converter 1 is used as a ballast having a full bridge 4, which converts an input voltage 2, 2 'in a bipolar voltage with a predetermined frequency and voltage and at the output 16, 16' of the inverter 1 for the lamp 8 provides. The lamp 8 is connected via leads 17, 18, 19 with the outputs 16, 16 'of the inverter 1 via a series-connected throttle 13 as a current limiting element. However, other means limiting the current can be provided as the throttle 13, for example, directly within the inverter 1. However, the throttle 13 is a particularly easy-to-implement device and is robust. Therefore, it is preferably used.

The full bridge 4 is operated via a driver circuit 3 and controlled by a control unit 14 via a supply line 6 for the specification of desired values (eg via a respective setpoint generator) such that the frequency and the voltage at the lamp 8 are selected within wide ranges can. The DC voltage (DC) 5 at the input 2, 2 'or the output voltage at the converter 1 is detected by the controller 14 (for example by means of corresponding sensor arrangements) and processed according to the setpoint specifications, in particular for control purposes. Likewise, in the output circuit, measured on the load side of the lamp current 7, detected by the controller 14 and processed. The controller advantageously has an interface or is connected to one such as, for example, input and output lines 15 having a bus connection, e.g. a fieldbus to allow a higher-level process control.

The UV lamp 8 is arranged in a cassette-like lamp holder 9, which can be designed in a variety of ways, for example in the manner of, as the US 5,094,010 or the 5,343,629 it can be seen, wherein the holder 9 in the latter case is an insertion part. A reflector 21 is accommodated in the cassette-like lamp holder 9 in such a way that the radiation emitted by the UV lamp 8 impinges bundle on the respective substrate or object, for example a flat printed surface, and thereby does not overheat the lamp Substrates allows. For emitting the radiation 10 containing UV and IR light, the cassette 9 is opened in the front area or covered by a transparent plate, below which the workpieces to be treated or the substrate are placed. Between this light opening or the lamp 8 and the respective workpiece, a swiveling aperture with a controlled drive is advantageously provided as a shutter 20 in order to be able to carry out the exposure of the workpiece with UV light in a targeted and controlled manner. For simplicity, here the shutter 20 is shown as consisting of two linearly displaceable shutter blades, but it may take any known form in the art, so be a pivotable or rotatable shutter.

The drive of this shutter 20 is suitably controlled again by the controller 14. In order to be able to monitor the thermal operating state of the lamp 8 at any time, a temperature sensor 11 is advantageously provided in the region of the lamp 8, for example a platinum sensor, as it is known as PT 100, the signal of which is in turn detected and taken care of by the controller 14 (FIG. Regulation) that the lamp 8 is not thermally overloaded. However, it is also possible to provide other monitoring means 11, for example a sensor for detecting the UV radiation of the UV lamp 8, or several methods can be combined in order to be able to control the operating state of the lamp 8 at any time.

In addition to a reduction in performance, a cooling system may additionally be provided, as indicated by means of a cooling fan 22. From the prior art, such as the above-cited US patents, a water cooling is known, which could also be used here. The controller 14 is advantageously a programmable controller, such as a computer controller, a microcomputer controller or a so-called PLC controller. With this control 14, the lamp 8 can be ignited and operated in a gentle manner, which increases their life. The desired operating values are maintained, taking into account the delicate operating requirements, since the correct operation is constantly monitored. In addition, age-related changes can be automatically compensated via the controller 14 and associated sensors by tracking at least one of the parameters of power and / or time of UV exposure, for example via an output line 23 of the controller 14 and the cooling or temperature regulated becomes, for which the sensor 11 is particularly advantageous as a temperature sensor.

In addition, the shutter 20 can be used for precise adjustment or correction. Thus, the inventive method allows a flexible and application-specific operation.

If now under the lamp 8 indicated by an arrow 24 transport system, such as a conveyor belt for supplying workpieces, in particular printed flat material is provided, which is driven by a drive motor 25, so it can to determine a sufficient irradiation with UV light 10 be advantageous to synchronize this drive 25 with the shutter 20. For this purpose, one, only shown schematically without the required Motoransteuerstufe, synchronizing 27 as the output of the control device 14 is provided. Depending on the application, the motor may then be speed-controlled in analogue form, but may be continuous, or it may be started intermittently synchronously with the shutter movement.

The same applies to the drive of the only schematically indicated turntable 26. This can, as shown, on the circumference cams (or recesses) have, which cooperate with the bearing switch 29, which then connected instead of the sensor 28 to the control unit 14 leading line 38 is. For this purpose, a switch S may be provided. In this case, the turntable motor can, for example, via a switch 29 bridging pulse in motion, whereupon the turntable cam removed from the switch, this is switched and then keeps the engine in motion.

Below the linear conveyor 24 is dashed as an alternative turntable or the like. Rotary drive 26 indicated, which can also be used continuously or (preferably) intermittently used to record each workpiece at one point and then bring under the lamp 8. The synchronization may be in both transport systems 24 and 26 by a sensor device, such as an optical sensor 28 for detecting the arrival of an edge of a printed sheet at a predetermined location under the lamp 8, or by a switch 29 as a position sensor for the position of the turntable 26, to be supported. Of course, a marker for a particular position for synchronization with the shutter 20 could also be provided on the belt 24, and it is also possible to completely dispense with a sensor by the motor 25 as stepper motor (or synchronous motor) is formed, which performs as many steps as the length of a printed sheet corresponds to bring it under the lamp 8.

If direct lines 23, 27 or to the sensor 28 are also shown here, which directly connect the parts 22, 25, 28 to the controller 14, then it goes without saying that these parts, if desired, are also linked to the superordinate control already mentioned and so indirectly via the interface 15 may be connected to the controller 14.

As a very suitable further possibility for an ignition device is in Fig. 1 an external ignition device 12 is shown, which outputs an ignition voltage to the lamp 8, which can be coordinated by the controller 14. This type of ignition can be used for individual specific dopings or special lamp geometries. However, operation via such an ignition preserves the lamp 8 somewhat less than the ignition directly with controlled frequency and voltage variation of the converter voltage itself, which is referred to herein as "internal ignition".

The internal ignition is based on a method in which over time a defined frequency and output voltage (U _{RMS_OUT} ) is set up. This method of igniting the UV lamp 8 requires as the only power components the inverter 1 and the choke 13 and 31, respectively. The course of the voltage as a function of time is in Fig. 2 shown, the course of the frequency in Fig. 3 , This variation of voltage and frequency results in a voltage-time area that is sufficiently large that it causes the UV lamp 8 to ignite. It uses the property of the voltage overshoot of a series resonant circuit, which is formed from the inductance of the inductor 13, 31 and the capacity of the UV lamp 8 itself. Because the lamp 8 can be idealized as a parallel connection of a capacitor and an ohmic resistance, wherein the capacity changes after ignition. This idealization of the UV lamp 8 is essentially defined by the lamp geometry and the filling. The ignition of the UV lamp 8 takes place at a voltage which results both when the positive voltage is reached and when the negative voltage is reached. The inventive concept realized in this way thus lies in the combination of the three components and a special method of varying the lamp voltage in combination with the frequency.

Starting from the point A, the frequency and at the same time the effective value of the output voltage at the converter 1 is preferably continuously varied or increased. The voltage is increased until the ignition occurs and the transition from the glow discharge to the arc discharge B is detected. The transition from B to D manifests itself in a very strong increase in current and can thus be detected easily. For a certain configuration and dimensioning of the arrangement of inverter 1, UV lamp 8 and throttle 13, the transition is in a known and repeatable frequency range F1, t1 to F2, t2. If the radiator 8 could not be ignited, then the controller 14 breaks off at point C, t2. After a short residence time then the ignition is new, for example, again at point A, started. The same applies to the voltage curve V1, t1 to V2, t2 according to the representation of Fig. 2 ,

For the burn-in phase, which the lamp 9 requires, the discharge current and / or the voltage is regulated to a defined value until the required operating point of the UV radiator 8 (temperature, power) is reached, that is in the point E.

After the end of the baking phase at E, the lamp 8 is set directly to the required target power F. From this point the lamp 8 is ready for use. However, it is possible, for example for dimming, to vary the power by varying the frequency to the point G, which is shown here as a reduction of the frequency. The phases from the point G to the points H, K and L can be defined as actual production phase or process phase. In this phase, the shutter 20 is selectively opened and closed again after reaching the process window. For example, a standby state is activated at point H by increasing the frequency F and lowering the voltage V, which lowers the power. This state is deactivated, for example, in point J again. In the standby phase HJ, the shutter 20 is closed, the workpiece, substrate or area to be irradiated is changed for the next treatment, without the sensitive UV lamp 8 has to be switched off and re-ignited. This standby phase can also be used in translating presses during the retraction phase.

For the power control or adjustment, the frequency-dependent resistance of the throttle can be exploited. This means: To increase the output power, the frequency must be reduced, namely from point F to Points G. Conversely, for a power reduction, the frequency must be increased, for example, from the point E to F or from H to I. If you consider the structure idealized (UV emitter 8 as ohmic consumer, inductance as RL combination), Thus, the radiator performance can be calculated without knowing the characteristics of the radiator 8. For the calculation, the current I, the frequency f, the output voltage of the inverter U _OUT and the inductance L of the choke are then sufficient.

However, the power can also be set in an advantageous manner by adjusting or by controlling the voltage for influencing the current, or it can also be done in combination with the frequency variation by the inverter 1 is driven by the control unit 14 accordingly. The voltage setting is made in the inverter 1 by setting a specific pulse width ratio, whereby after the choke on the lamp 8, a mean DC voltage value (DC) appears.

In the 4 and 5 is shown in an analogous manner, the voltage waveform and the frequency response for the case that the ignition is performed by an external ignitor 12. The ignition is done by superimposing an excessive voltage, for example by a voltage pulse in the points D, ti, wherein the inverter 1 is operated at a fixed predetermined frequency and fixed voltage to the lamp 8 and then after ignition, as described above, the Power values for the burn-in phase and the operation by setting the frequency and the voltage is set or regulated. When using an external ignition device 12 as a starting aid, the arrangement is preferably operated over all operating phases with a constant frequency, for example, with a few hundred Hz, for example with 250Hz.

In the following Table 1 are the various states as shown in the Fig. 2 to 5 are listed for an overview: <b> Table 1: </ b> Point operating mode description A to B ignition Glow discharge and / or arc discharge in the small power range A to C ignition Without ignition B to D ignition Change from glow to arc discharge, detection due to very strong current increase D to E burn-in current-controlled burn-in phase until the operating temperature of the lamp is reached C to R ignition Restart of the ignition after failed ignition R to A ignition restart E to F business operational F to G business Power adjustment (dimming) G to H business Production phase without power control H to I business Change to standby I to J. business standby J to K. business Change of operating mode K to L business Production phase with power control by varying frequency and / or voltage F1 ignition minimum ignition frequency Fi ignition Ignition frequency with successful ignition F2 ignition maximum ignition frequency T1 ignition first possible ignition Ti ignition Time of ignition T2 ignition latest possible ignition

The above-mentioned characteristics are not exhaustively enumerated. After the ignition D of the UV lamp 8, for example, this can occupy any desired operating point. Intermediate values for the desired lamp power, for the full power, for the standby mode, the shutter operation as well as at which time these intermediate values take place can be adjusted by the user on the controller 14 (eg in the program, eg via the software) or by the higher-level process control Need to be specified.

Important numerical values will now be given by way of example in Table 2 below. In addition, the important work areas for the operation are shown, especially for the most important components, such as inverter, choke and UV lamp as well as for an external ignition aid: <b> Table 2: </ b> minimum value Typical value maximum value inverter Maximum output power [kW] 0.5 10 30 Maximum output voltage [V] 10 450 1800 Maximum output current [A] 1 30 60 Maximum output frequency [Hz] 1 3000 100000 throttle Inductance [mH] 0.01 2 100 Rated current [A] 1 20 60 UV lamp Specific rated power [W / cm] 130 Rated power [W] 500 4000 30000 Radiator voltage [V] 230 380 1600 Radiator current [A] 1 10 40 Short-circuit current [A] 22 ignition aid Charging voltage [V] 10 150 1000 Gear ratio [u] 15 5 20 Limiting the output voltage [V] 10 4000 15000 Voltage switch (24) [V] 1 800 50000 Charging capacitor (25,26) [nF] 1 500 50000

For a specific configuration of inverter, choke, and UV lamp, another numerical example of a voltage / frequency characteristic is given in the following Table 3, for which the operating points correspond to those of FIG FIGS. 2 and 3 to go through: <b> Table 3: </ b> Point Voltage [V] Frequency [Hz] description A) 10 1 Start, ignition B) 150 100 UV lamp has ignited C) 250 150 Termination of the ignition phase D) 360 1200 Start, baking phase e) 420 1000 Burn-in phase with current control, setpoint to I _nominal , finished when lamp reaches 110 ° C F) 420 3000 Change to minimum performance G) 420 200 Set production phase H) 310 3000 Set standby power I) 310 3000 standby J) 420 3000 Set production phase (operating phase) K) 420 200 production phase L) 420 200 production phase R) restart

The inventive method is particularly suitable for lamp operating power in the range of 0.5 to 30 kW at current values of 1A to 60A. For the operating phase, ie when the lamp 8 is operating in power mode, the converter 1, without the ignition, voltages and at least in the range of 10 to 1600V, but preferably in the range of 10V to 500V, in particular variable, generate and can deliver. For ignition, the arrangement should be designed in such a way that an ignition voltage> 800 V is achieved at the lamp 8 is, preferably> 1000V, but highest 6000V. The frequency of the output voltage of the inverter 1 should be within the range of 1 Hz to 100 kHz, preferably in the range of 1 Hz to 10 kHz, and should be suitably varied. The bipolar voltage is in this case substantially symmetrical and advantageously substantially rectangular. The feeding of the lamp 8 is conveniently carried out by a single inverter 1, which is advantageously used on the market standard component.

After successful ignition D of the UV lamp 8, this is thus brought into a defined operating state. This phase includes a power control and / or control, preferably in the form of a current control. This phase continues until thermally sufficient conditions are reached. Typically, above all the conditions within the cassette 9 are of interest, and here too, in particular those of the UV lamp 8.

For the normal operation (production) beginning after reaching the thermally sufficient conditions, the power variation can be adjusted by adjusting the frequency and / or the output voltage. The standby power is adjusted by adjusting the output voltage and / or the frequency.

If the internal ignition method (point A to D) is used, as mentioned, for example, an external ignition device 12 can be completely dispensed with. In this case, the voltage at the converter output 16, 16 'is varied in such a way that frequency and voltage reach a value (voltage-time surface) defined for the ignition of the UV lamp 8, which fulfills the ignition conditions. With this ignition method according to the present invention, the UV lamp 8 is ignited with fewer components, and also gentler.

With the use of commercially available modules, customer benefit can be created in terms of quality (standard product), flexibility (PLC) and scalability (performance classes). The conveniently programmable controller 14, such as a PLC controller, may include additional functions such as control of the shutter 20, communication, and the like. provide. A possibly provided bus connection (Profibus, Ethernet, etc.) allows coupling to a higher-level control.

Also, throughout the system certain components, as mentioned, are subject to aging but are relevant to UV cure (e.g., UV lamp, mirror, etc.). Here, the controller 14 allows an adjustment of important operating parameters that change due to aging, so as to ensure optimum conditions for the curing process over the entire lamp life.

In certain types of UV lamps, however, an external ignition device 12 is preferred in order to achieve a safe ignition, as shown schematically in FIG Fig. 6 is shown. Such lamps, for example, have a smaller diameter or a different doping, which makes the ignition more difficult. The advantage of such a starting aid (36) is that only low-power components are used, but not the operating current for the UV lamp flows through the exclusive auxiliary power. For this purpose, the additional, external ignition device 12 is connected as a starting aid in the power circuit with the negative line 39 and the positive line 40. The ignition device 12 includes a transformer 30 having two windings 31, 32, which are coupled together via a ferromagnetic core, and an electrical circuit, the Zündhilfenbeschaltung 36. The one winding is formed as a main winding 31 and takes over the function of the throttle 13, 31 as the current limiting element, which is connected in series in one of the lamp leads 39, 40. In this case, it does not matter whether this throttle 13, 31, is integrated in the negative line 39 or in the positive line 40. For the external ignition of the transformer 30 can be performed with throttle 31 and ignition coil 32 as a single component.

The second winding 32 represents the ignition winding, and via this potential, a firing voltage via its two terminals 33, 34 is coupled. The ignition voltage is provided at these two terminals 33, 34 by a Zündhilfenbeschaltung 36, which in turn via its two terminals 35, 37 refers to a supply voltage from the lamp connection lines 39, 40. This Zündhilfenbeschaltung 36 includes a Spannungsvervielfacheranordnung, which generates from the provided at the inverter 1 lamp supply voltage to safely ignite the lamp 8, a correspondingly increased voltage. In most cases, a voltage doubling is sufficient, which is preferred. In addition, it is advantageous, the ignition voltage across the feed line 17, 18 and 39, 40 of the UV lamp 8 with to limit a voltage limiter 46, so that the ignition voltage is substantially independent of the cable length used and the lamp 8 can still be safely ignited. Such a voltage limiter can also be provided directly in the Zündhilfenbeschaltung 36 via the feed terminals 35, 37. The Zündhilfenbeschaltung 36 is operated via a switch 47 such that it is active only in the ignition phase and deactivated in the operating phase of the lamp 8 (eg off). For this purpose, the switch 47 is actuated by the control unit 14 via a control line 48.

The schematic of a preferred arrangement for a priming circuit 36 is shown in FIG Fig. 7 shown schematically and corresponds substantially to the in Fig. 1 shown arrangement. The circuit for the voltage increase is preferably made of passive electronic components. An expedient embodiment is constructed as follows. A capacitor and a diode are electrically connected in series with each other, which in turn are connected in parallel with a further, separate series circuit of a capacitor and a diode. The two diodes 44, 45 are connected in anti-parallel. On one side of the first terminal 35 of the UV lamp 8 is connected, and on the other side via an activation switch 47, a second terminal 37 of the UV lamp. Parallel to the first terminal 35 and the second terminal 37, a voltage limiter 46 is provided. However, as already mentioned, the polarities can also be interchanged, ie the polarity of the ignition pulses can be positive or negative.

This Zündhilfenbeschaltung 36 can be advantageously adapted to existing chokes 13 with an additional auxiliary winding 32, so as to provide the possibility of retrofitting existing circuit. The output lines 33, 34 of the ignition assistance circuit 36 lead, for example, in the in Fig. 6 shown manner to ignition coil 32nd

If the inverter 1 is turned on, the ignition aid 12 is activated. The capacitors are charged with a voltage doubling circuit until a defined voltage level is reached. The stored charge is discharged from the capacitors via the voltage switch and transformer 30 to the lamp 8. The two windings 31, 32 are used for the transformation of the ignition voltage. From the ignition winding 32 to the main winding 31, the voltage is transformed up. The voltage of the transformed charge is at least so large that the ignition of the lamp 8 is made possible. The main winding 31 is also used for smoothing the lamp current.

In the Zündhilfenbeschaltung 36 the required energy for the ignition (voltage-time area) is stored by charging the capacitors 42, 43 to different voltage potentials. The diodes 44, 45 and capacitors 42, 43 are connected to provide voltage multiplication (e.g., voltage doubling). If the charge is sufficiently large, i. the charging voltage reaches a predetermined, possibly adjustable, switching threshold of the voltage switch 41, so this is delivered to the ignition winding 32. The ignition energy is up-converted with a conversion from the ignition winding 32 to the main winding 31. The output voltage (ignition voltage) is limited by means of a voltage limiter 46 and thus independent of the line length used 39, 40. The ignition aid 12 is activated with a switch 47 during the ignition phase, but deactivated in the operating phase. As long as the switch 47 keeps the ignition aid 12 in operation, this successively generates ignition pulses, which are defined in time by the wiring until the lamp 8 ignites and then the controller 14 via the switch 47, the ignition aid 12 again disabled.

The preferred method of ignition with an external ignitor 12 thus comprises the following steps:

An ignition voltage is by charging at least two capacitors 42, 43 to voltage potentials for storing the energy required for the ignition, wherein the diodes 44, 45 are connected to the capacitors 42, 43 such that at least one voltage doubling is achieved. When the desired predetermined charging voltage reaches a corresponding switching threshold of a voltage switch 41 (threshold value switch), it is output when switching on to the ignition winding 32 of the transformer 30. Thereby, the ignition energy is up-converted to a predetermined value with conversion from the ignition coil 32 to the reactor 31 constituting the main coil. Now ignited or the ignition process, for example by means of the switch 47, activated for the ignition phase, but then deactivated in the operating phase.

• Das UV-System ist ein eigenständiges, komplettes System zum Ansteuern von UV-Lampen einschliesslich der Temperaturregelung und der Ansteuerung des Shutters;
• es handelt sich um ein Standardprodukt, bei dem daher leicht eine hohe Qualität, Zuverlässigkeit, auch in grossen Leistungsklassen erreicht werden kann, wobei auf Grund der Standardisierung die Zulassung durch Behörden im Ausland erleichtert und ein grosses Service- und Ersatzteilnetz gesichert ist, was die Wirtschaftlichkeit insgesamt erhöht;
• bevorzugt kann eine industrielle Busankoppelung verwendet werden, wie CANopen, Profibus etc.;
• in Form einer SPS kann ein zusätzlicher Kundennutzen erzielt werden, die sich für die Temperaturregelung, die Shutteransteuerung eignet und als integrierte SPS auch für den Kunden, z.B. für eine Anlagensteuerung, nutzbar ist;
• da UV-Lampen auf Temperatureinflüsse sehr empfindlich sind, ist eine integrierte Temperaturregelung von Vorteil. Denn die Temperatur hat einen entscheidenden Einfluss auf die Lebensdauer, das Lichtspektrum u.dgl. Eine schnelle, Kommunikation zwischen der Ist-Temperatur und der Soll-Lampenleistung ist daher sinnvoll.
• die Lampenlebensdauer wird über die sich mit der Betriebsdauer verändernden Zündparameter bestimmt, so dass auch Serviceeinsätze planbar werden (z.B. bei Farbwechsel od.dgl.).
• die Lebensdauer der Lampe wird merklich erhöht, weil, insbesondere für eine interne Zündung, nur die erforderliche Zündenergie ohne schockartige Zündimpulse aufgebracht wird. Dies reduziert Stillstandszeiten und ServiceEinsätze;
• die vorrichtungsmässige Realisierung ist einfacher und kostengünstiger zu bewerkstelligen, da nur wenige zusätzliche Bauteile erforderlich sind;
• die Betriebsparameter der Spannung und/oder der Frequenz beim Betrieb der UV-Lampe 8 und/oder des Shutters 20 können - abhängig von der Alterung der Lampe 8 - mit Hilfe der Steuerung 14, z.B. mit Hilfe eines eingebauten Betriebsstundenzählers, nach vorgebbaren Werten nachgeführt werden;
• die Betriebsparameter für verschiedene Lampentypen und Prozesskenngrössen lassen sich über die Software verändern und bedürfen für präzise Prozesse nicht mehr einer genau angepassten Hardware;
• da in der Industrie laufend neue Standardgeräte entwickelt werden, braucht die Hardware nicht immer wieder angepasst werden, wenn etwa bestimmte Teile nicht mehr erzeugt werden.

The method according to the invention achieves the following improvements:

• The UV system is a self-contained, complete system for controlling UV lamps, including temperature control and shutter control;
• it is a standard product, which therefore easily high quality, reliability, can be achieved even in large power classes, with the standardization facilitates the approval by authorities abroad and a large service and spare parts network is secured, which is cost-effective increased overall;
• preferably an industrial bus coupling can be used, such as CANopen, Profibus etc .;
• in the form of a PLC, an additional customer benefit can be achieved, which is suitable for temperature control, the shutter control and as an integrated PLC for the customer, eg for a plant control, is available;
• Since UV lamps are very sensitive to the effects of temperature, integrated temperature control is an advantage. Because the temperature has a decisive influence on the life, the light spectrum and the like. A fast, communication between the actual temperature and the target lamp power is therefore useful.
• the service life of the lamp is determined by the ignition parameters which change with the duration of operation so that service interventions can also be planned (eg when changing colors or the like).
• the life of the lamp is significantly increased, because, in particular for an internal ignition, only the required ignition energy is applied without shock-like ignition pulses. This reduces downtime and service interventions;
• the device implementation is easier and cheaper to accomplish, since only a few additional components are required;
• the operating parameters of the voltage and / or the frequency during operation of the UV lamp 8 and / or the shutter 20 can - depending on the aging of the lamp 8 - be tracked by the controller 14, for example by means of a built-hour meter, according to specifiable values ;
• the operating parameters for different lamp types and process parameters can be changed via the software and no longer require exactly adapted hardware for precise processes;
• As new standard devices are constantly being developed in the industry, the hardware does not have to be adapted again and again if certain parts are no longer produced.

• Trocknen und Härten von Flüssigkeiten, Gelen, Klebstoffen, Lacken, Farben usw.;
• Hervorrufen chemischer Reaktionen (z.B. Auftrennung von DNA-Strängen etc.);
• Unterstützung anderer chemischer Prozesse;
• Belichtung von photoaktiven Materialien (Lithographie);
• Fluoreszenzanregung verschiedener Stoffe, etwa zum Prüfen von Banknoten.

The method according to the invention is advantageously used in the following fields of application:

• Drying and curing liquids, gels, adhesives, paints, paints, etc .;
• Inducing chemical reactions (eg separation of DNA strands etc.);
• Support of other chemical processes;
• Exposure of photoactive materials (lithography);
• Fluorescence excitation of various substances, for example for checking banknotes.

LIST OF REFERENCE NUMBERS

1

inverter

3

Driver circuit for 4

5

DC voltage at 2, 2 '

7

Lamp current (load side)

9

cassette-type lamp holder

11

"Monitoring means", radiation sensor

13

throttle

15

Input / output lines (interface)

17

Feeder of 8

19

Supply of 8

21

lamp reflector

23

Output line of 14

25

Drive motor for 24

27

Synchronization line to 25

29

Position sensor (switch)

31

Throttle to 12

33

Connection of 32

35

first connection of 8

37

second port of 8

39

Cable length in 12

41

Voltage switch (threshold) v. 12

43

Capacitor of 12

45

Diode of 12

47

(Zündauslöse-) Switch

2, 2 '

Inputs from 1

4

full bridge

6

Supply of 14

8th

lamp

10

Radiation from 9

12

external ignitor

14

control

16.16 '

inverter output

18

Feeder of 8

20

shutter

22

cooling fan

24

transport means

26

turntable

28

opt. sensor

30

Transformer of 12

32

Ignition winding of 30

34

Connection of 32

36

Ignition aid circuit for 12

38

Position sensor line

40

Performance length in 12

42

Capacitor of 12

44

Diode of 12

46

Voltage limiter of 12

48

Control line from 14 to 47

Claims (27)

1. An apparatus for operating a UV lamp (8) having electrodes,
   comprising
   a transverter (1) having outputs (16, 16') for producing a bipolar feed voltage at said outputs (16, 16'), which is supplied to said UV lamp (8) via supply lines (17-19),
   a current-limiting element (13), connecting said UV lamp (8) to said outputs (16, 16') via said supply lines (17-19);
   wherein said transverter (1) further comprises voltage rectifying means, which are connected to a supply network via rectifier terminals, as well as an electronic control unit (14);
   said electronic control unit (14) being formed in such a manner that a frequency at the output of said transverter (1) and the effective value of said bipolar feed voltage may be chosen, wherein the effective value of said bipolar feed voltage is adjustable by adjusting a predetermined pulse width relationship;
   the apparatus being formed in such a manner
   that after starting said transverter (1), said bipolar feed voltage is applied to said electrodes of said UV lamp (8), and an ignition operation (A, D) may be initiated at the discharge space of said UV lamp (8), ignition (D) effected being monitored by means of said electronic control unit (14);
   that a predetermined heating phase (D, E) of said UV lamp (8) is realised after said ignition (D) has been effected, said electronic control unit (14) determining, monitoring and processing it by means of monitoring means (7, 11, 38), wherein said electronic control unit (14) adjusts and/or regulates the effective value of said bipolar feed voltage and/or the frequency in such a manner that predetermined lamp specific parameters are kept;
   that after termination of said heating phase (D, E), a predetermined nominal lamp power may be given, by which readiness for operation of said UV lamp (8) is achieved, wherein said predetermined nominal lamp power is adjusted for a following operation phase (F, H, J, K, L) by regulating the frequency and/or the effective value of said bipolar feed voltage;
   wherein said electronic control unit (14) is formed to control the passing phases, and comprises a peripheral interface to put data at the disposal of a superposed control unit for further processing,
   characterised in that
   the apparatus comprises furthermore transport drive means (24, 25, 26) for transporting a substrate to be irradiated, particularly flat material, as well as a shutter (20), wherein said electronic control unit (14) is formed to synchronise said transport drive means and said shutter and to operate said shutter (20) during said operation phase (F, H, J, K, L) of said UV lamp (8) in correspondence with given process points.
2. Apparatus according to claim 1, characterised in that said current-limiting element (13, 31) comprises a choke (31) in series to said UV lamp (8).
3. Apparatus according to any of the preceding claims, characterised in that the apparatus comprises a series-resonant circuit formed by the capacity of said UV lamp (8) and the choke (31), wherein it is caused to be in resonance by varying the frequency and/or the effective value of said bipolar feed voltage, thus producing an ignition energy for igniting (B, D) said UV lamp (8).
4. Apparatus according to any of the preceding claims, characterised in that both the frequency and the effective value of said bipolar feed voltage are varied during the ignition operation (A, D).
5. Apparatus according to any of the preceding claims, characterised in that both the frequency and the effective value of said bipolar feed voltage are simultaneously increased during the ignition operation (A, D).
6. Apparatus according to claim 2, characterised in that said choke (31) is formed as the coil of a transformer (30) having a core of a ferro-magnetic material, and that said transformer (30) is electromagnetically coupled to a further ignition coil (32).
7. Apparatus according to claim 6, characterised in that the apparatus comprises a controlled ignition aid (12), which is connected to said transverter (1) and comprises merely low power components, only auxiliary energy passing said controlled ignition aid (12).
8. Apparatus according to any of the preceding claims 6 or 7, characterised in that said controlled ignition aid (12) produces an additional ignition voltage of a voltage/time area to be given, which, during ignition (B, D), is superimposed to said bipolar feed voltage.
9. Apparatus according to any of the preceding claims 6, 7 or 8, characterised in that said controlled ignition aid (12) comprises said further ignition coil (32).
10. Apparatus according to any of the preceding claims 6, 7, 8 or 9, characterised in that said controlled ignition aid (12) comprises an ignition aid circuit (36), which is formed as a voltage multiplier arrangement, preferably as a double voltage multiplier arrangement.
11. Apparatus according to the preceding claim 10, characterised in that said ignition aid circuit (36) comprises at least two condensers (42, 43), diodes (44, 45), a voltage switch (41) and a switch (47) and is formed in such a manner that the ignition voltage is produced by charging said at least two condensers (42, 43) up to voltage potentials for storing the necessary energy for ignition, wherein the two diodes (44, 45) are connected to said at least two condensers (42, 43) in such a manner that at least a voltage duplication is attained,
    and that, when the given charging voltage attains the given switching threshold of said voltage switch (41), it connects through, and is released to said ignition coil (32) of said transformer (30) by connecting through, by which the ignition energy, with a transformation from said ignition coil (32) to said choke (31), forming the main coil, is transformed up according to a given value and is superimposed to said bipolar feed voltage, by which said UV lamp is ignited.
12. Apparatus according to the preceding claim 11, characterised in that said ignition aid (12) is respectively activated during the ignition phase, and is deactivated in the operation phase by said switch (47).
13. Apparatus according to any of the preceding claims, characterised in that the frequency and/or the effective value of said bipolar feed voltage is adjusted in the operation phase (F-L), wherein the effective value of said bipolar feed voltage is adjusted and/or regulated by adjusting the predetermined pulse width.
14. Apparatus according to any of the preceding claims, characterised in that the apparatus is formed in such a way
    that a change of the lamp power may be made to a stand-by value within said operation phase (F-L) by increasing the frequency and reducing said bipolar feed voltage without extinguishing the discharge of said UV lamp (8) so that it has to be ignited anew, and that subsequently the operation phase (F-L) is continued with the previous lamp power by decreasing the frequency and by increasing the bipolar feed voltage.
15. Apparatus according to any of the preceding claims, characterised in that the output power can have values which are within a range of 0.5 to 30 kW, and current values which are within a range of 1A to 60A.
16. Apparatus according to any of the preceding claims, characterised in that the bipolar feed voltage, for operation without an additional ignition voltage, produces at least a value within a range of 10V to 1600V, preferably within a range of 10V to 500V.
17. Apparatus according to any of the preceding claims, characterised in that the frequency comprises values within a range of 1 Hz to 100kHz, preferably within a range of 1 Hz to 10kHz.
18. Apparatus according to any of the preceding claims, characterised in that the ignition voltage is higher than 800V, preferably higher than 1000V.
19. Apparatus according to any of the preceding claims, characterised in that the bipolar feed voltage is substantially symmetrical, preferably substantially rectangular.
20. Apparatus according to any of the preceding claims, characterised in that the electronic control unit (14) is a computer control unit or a microcomputer control unit or an SPS control unit.
21. Apparatus according to any of the preceding claims, characterised in that said monitoring means comprise at least one sensor.
22. Apparatus according to claim 21, characterised in that said at least one sensor comprises a temperature sensor for determining the temperature of said UV lamp (8), and which provides a temperature measuring signal to determine the operational condition of said UV lamp (8) and/or to regulate lamp cooling means.
23. Apparatus according to claim 21, characterised in that said at least one sensor comprises an emission determining sensor for determining the UV emission of said UV lamp (8) and provides an emission measuring signal to determine the operational condition of said UV lamp (8) and/or to regulate lamp cooling means.
24. Apparatus according to claim 21, characterised in that said at least one sensor comprises a sensor for determining the position of the substrate to be irradiated and for providing a measuring signal for synchronisation.
25. Apparatus according to any of the preceding claims, characterised in that the electronic control unit (14) comprises a field bus coupling for operating said superposed control unit.
26. Apparatus according to any of the preceding claims, characterised in that means are provided for determining ageing of said UV lamp, and that the apparatus is formed in such a way, that the frequency and/or the effective value of said bipolar feed voltage are followed up in dependence on ageing of said UV lamp (8) according to values to be given.
27. The use of an apparatus according to an of the preceding claims for curing UV curable materials, such as polymers, varnishes or adhesives.

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