Supply circuit for gaseous discharge lamps.

p0001The invention relates to a method and a circuit arrangement for the supply of gas discharge light sources.

p0002The invention is particularly useful when taking place by means of electronic RF Power supply of gas discharge light sources.

p0003For ignition of light sources, which require a high starting voltage, high-voltage high-frequency pulses have been exclusively used and in the manner that such an operating voltage were overlaid, and were synchronized in order to ensure that forms immediately after ignition, the operating current , The various known methods differ from each other only in the production of pulses in the overlay to the operating voltage or in this occurring synchronization. The shortcomings of the superposition and synchronization often lead to inconclusive attempts at ignition, whereby the decay, the aging of the cathode is accelerated.

p0004The ignition pulse is generated in most cases by means of a in the lamp circuit series-connected transformer in the manner that on the primary coil, a capacitor is discharged, such a solution is known from GB-PS 1397031 is known in which by means of a manually actuated switch, a capacitor via the primary coil of a coil with its secondary to the discharge lamp is connected in series transformer discharge. The energy of an ignition pulses generated in this way is constant, and be thus damaged, the new lamp superfluous, since the ignition voltage is lower. After ignition sure this solution via serial, passive control, the corresponding power of the light source.

p0005The ignition circuits in general repeat the ignition process until an operating current begins to flow, or to a nascent fehlerhaf element (eg a bimetallic Glimmentladungszünder) of the ignition circuit fails. In connection errors (if can not train due to a failure of the supply circuit, the operating current) damage such attempts at ignition, the cathode of the intact lamp also. When the ignition of gas discharge light sources, resulting in the unloaded state of the feed transformers large reignition is used in a significant part of the known solutions. This re-ignition will depend to a great extent by the supply voltage and the excitation.

p0006For ignition of gas discharge lamps, for example, a solution is known from US Pat. No. 4,004,188 is known in which the ignition means of a separate ignition electrode, an ignition transformer takes place. This technical solution includes a high-voltage pulse generator is supplemented by a timing generator. This patent deals with the synchronization means of an inverter.

p0007From the literature, processes are known which limit the at the collector of the output transistor of the (fly back voltage) in order to avoid that the voltage increases in an impermissible extent. These methods have the common characteristic that they derive the erscheibende more energy by any circuitry, thus the chip is voltage peak limited, but this will also be a significant loss caused. Serve this purpose as the methods and circuitry for realizing a slow voltage rise.

p0008In order to regulate the gas discharge light source power supplied to a plurality of different methods are also known. In self-oscillating converters a controlled into saturation magnetic circuit based on the saturation current realized an approximately power-proportional control, but that depends to a significant extent on the supply voltage and the impedance of the light source. Therefore, a short-term increase of the supply voltage leads to a significant overload, which leads to a reduction in the life of the light sources. Since the impedance of the gas discharge light source is negative and depends on many factors (gas pressure, temperature, operating voltage and current, etc.), the deviations in the production and the environmental effects result in significant differences and instability.

p0009In gerg sparkled Spannungsunformern the current of the light source is stabilized (see, for example, the above GB-PS), which occur as a result of environmental influences and power fluctuations, however, the dispersion of the internal voltage can not be prevented in general. In the last third of the life of the light sources occurs a significant increase in the operating voltage and the ever increasing lamp power accelerates the harmful detention If the lamps.

p0010A common disadvantage of the known solutions is that this relatively complex and expensive circuit units claims or a manual operation is required. In the application of high-frequency operating voltage, the disadvantages are still increased in that in the additive superposition of the firing pulse, the separation of the on operating circuits due to the proximity of the frequencies can not be completely secured, so the reaction of the ignition leads to further disadvantages. Due to the comparability of the impedances to high losses.

p0011The aim of the invention is to remedy the disadvantages of the known solutions and to develop a method and a circuit arrangement by means of which the adverse effect of the factors which lead to the reduction of the service life of the gas discharge light sources can be reduced.

p0012The invention is based on the insight that, in particular in the high frequency range (20-100 kHz), the ignition pulses, which contain the frequency components of 100-1 MHz, in terms of their effect can not be separated from the primary circuit, the pulses but which is opposite to one of the have time period substantially lower time constant, can be effectively separated and can be done with these ignition with greater certainty. The invention is also based on the recognition that the the ignition pulse storage capacitor can be connected directly to the power circuit of the light source, which can thus combine the functions of the separation of low frequency.

p0013A further finding made it possible to simplify the realization of the circuit arrangement and indeed, that the ratio of without damage to the light source from the light source endured DC component can be the operating current substantially greater than the ratio of the operating impedance of the light source for cold resistance of the light source. This means that the internal impedance of the serving for the charging of the ignition capacitor high-voltage circuit can be selected so large that are negligible during operation even without switching off the high voltage of the source through the light flowing direct current and the resulting in the ignition circuit losses.

p0014Another finding of the invention is based on that increased significantly by improving the function parameters of the Power, the stabilization of the ignition voltage in the entire range of the supply voltage and / or the stabilization of the votes on the light source power in a wide range of environmental effects, the service life of the gas discharge light sources can be. It was recognized that in the unloaded or lightly loaded output transformers of Power, the restarting voltage is variable in extraordinarily wide limits by changing the energizing time. (In the other parts of the specification are "unencumbered" by analogy to the low miteinbegriffen moderately polluted circuits under the term.)

p0015It has also been found that the ignition characteristics of the gas discharge lamp is not deteriorated with an increase in the frequency of the ignition pulses.

p0016This fact is surprising, since based on the Penning effect due to the durability and the excitation energy of the metastable state of the filling gas, a reduction of the Zündbereitschaft would be expected.

p0017It has been further recognized that in order to stabilize the output power of the stabilization of the power absorbed by the Power output by changing the duty factor of the output voltage - under service factor is the expressed as a percentage of the period time switch understood - is sufficient, ie from the caused by the environmental change efficiency fluctuation of the voltage converter may be waived.

p0018The object of the invention is therefore to increase the service life of the gas discharge light sources by reducing the profit or non-ignition attempts and / or prevention of overloads during operation. The success loose ignition attempts can be reduced by increasing the Zündbereitschaft.

p0019The invention relates to a process for the ignition of gas discharge light sources, with a regulated operating AC voltage is applied to said gas discharge light source and in accordance with the invention, the circuit of the gas discharge light source is interrupted with respect to the direct current, further, the operation alternating voltage, a DC voltage is superimposed, the DC voltage will be increased, until extending through the superposition of the AC operating voltage and the DC voltage resulting, a DC voltage component and an AC component-containing voltage exceeds the firing voltage of the gas discharge light source and the gas discharge light source is ignited.

p0020In an implementation form of the invention required to produce the DC component of current after the ignition of the gas discharge light source is turned off.

p0021In a further preferred form of implementation of the invention, required to produce the DC component of current to several order of magnitude is selected to be smaller than the operating current of the gas discharge light source and maintained after ignition.

p0022For carrying out the inventive method further comprises a circuit arrangement has been formed, which has a transformer whose inputs are applied to a controlled operating alternating voltage and is formed according to the invention, the transformer with high-voltage outputs which are fed to a rectifier, while the output of the rectifier via a current limiter is guided to a terminal of the gas discharge light source, to this terminal further including a terminal of locking the operating current is coil of the transformer via an isolating capacitor applied while the other terminal of the gas discharge light source is directly connected to the other terminal of locking the operating current coil of the transformer.

p0023For carrying out process a further circuit arrangement is provided in which a terminal of a Betriebswechelspannung an operating current limiting impedance is created, wherein according to the invention, the impedance is connected via a decoupling capacitor to a terminal of the gas discharge light source, while the other terminal of the gas discharge light source to the other terminal of the regulated operating alternating voltage is guided, between the common node of the impedance and the separating capacitor and the other terminal of the AC operating voltage, a primary coil of a transformer is connected, whose secondary coil is connected to a rectifier, while the output of the rectifier via a current limiter with a connected terminal of the gas discharge light source.

p0024The invention weriterhin relates to a method for producing a composition suitable for powering gas discharge light sources, controlled operation AC, the occurring in unloaded Antreibstransformatoren restarting voltage is to increase Zündbereitschaft the gas discharge light source is used and / or given to the gas discharge light source power by changing the operating factor (DUTY CYCLE) the output voltage is regulated and in accordance with the invention, the optimum ignition voltage of the light source and is necessary to achieve the optimum ignition voltage reignition be found, which is associated with a predetermined reference voltage value, further the drive transformer on a selected supply voltage in the usual voltage converters frequencies corresponding limits for any time duration is energized, the current of the primary circuit at high speed is interrupted, and is led out a signal proportional to the restarting voltage signal from the drive transformer after the voltage proportional to the restarting voltage signal with the reference voltage value is compared and in case of deviation the energizing time of the transformer - by means of a to be known value hold control - changes in the way is that when compared with the reference voltage value lower signal value increases the excitation time and at a relative to the reference voltage value larger signal value, the energization period is reduced and / or controlled the output of the voltage converter in the manner that the output power with the power dissipation is added and as a result, absorbed by the supply source, nominal input power is obtained, which is associated with an internal reference value, that furthermore during operation of the voltage converter the instantaneous power absorbed, or of an associated value of an electrical variable is compared with the internal reference value, is amended - by a value hold control is known per se - in deviation of the operating factor of the output voltage.

p0025In one embodiment of the method of the instantaneous power of the voltage converter is determined in the manner that the current supply voltage of the voltage converter and the absorbed current are measured and the product of these measured values ​​is formed.

p0026In another embodiment, the internal reference value determined at nominal power of the voltage converter nominal signal value is assigned, besides the instantaneous supply voltage and the instantaneous current are measured, proportional thereto signals are formed, wherein the current supply voltage and the instantaneous current measured circuit elements are selected to that at the nominal value of the proportional signals to each other - and associated with the half of the nominal power signal value - match, Further, the instantaneous power absorbed, the sum of the signals.

p0027This embodiment will be explained below for a better understanding and by way of numerical example closer. It is assumed here that the nominal parameters of the Spannungsunformers are: 20V, 1A as an internal reference value is 1V determined then the invention, the chosen, the instantaneous supply voltage and the current drawn measured circuit elements on the way in this form of implementation that nominal at this value of the current eye to the supply voltage and the power absorbed proportional signal value 0.5V. If the nominal current to 2H increased (to twice), the value of the current measured Schaltungsselementes is to reduce to half, in order to ensure that the signal generated at the nominal value also amounts to 0.5V.

p0028In this implementation of the invention, although the percentage size of the error committed is greater than that of the real - based on the product of current and voltage - power control, but this embodiment is extremely advantageous due to the simpler design of the circuit and the important clotting Geren manufacturing costs.

p0029To perform the method for producing a composition suitable for powering gas discharge light sources, controlled operation AC voltage circuitry was created, a control unit, an up having the control unit subsequent drive unit and connected to the drive unit transformer, the outputs of the transformer, the outputs of the circuit (voltage converter ) form. According to the invention, the transformer is provided with a further output terminal to which a feedback unit is connected, whose output is connected to an input of a control unit, while the output of the control unit is connected to an input of the drive unit and / or the control unit is a unit for forming having a power proportional signal.

p0030In an advantageous embodiment of the invention, the transformer having a feedback coil is provided, while the feedback unit comprises a diode and a filter capacitor, an output terminal of the feedback coil is connected via the diode to the filter capacitor and the common node of the diode and the filter capacitor forming the output of the feedback unit , It is further advantageous if the control unit is arranged a Zener diode, whose one terminal is connected to the input of the control unit and the other terminal to the output of the control unit.

p0031In a further embodiment of the invention, the unit to form a power signal proportional to a control transistor, whose emitter is connected to the other input terminal, which is guided via a current monitoring resistance to the combined node. The base of the control transistor is connected to the common point of a Spannungstei coupler, of which one resistor is connected with the combined node, while the other resistor is connected to a further input terminal of the voltage converter. The collector of the control transistor is connected to the output of the unit to form a power signal proportional.

p0032Further embodiments are set forth in the claims below. The invention based on preferred embodiments with reference will be explained in more detail to the accompanying drawings.

p0033In the drawings:<ul><li>FIG. 1 shows an embodiment of the inventive circuit arrangement for ignition of gas discharge light sources with transformer adjustment,</li><li>Fig. 2 shows another embodiment of the inventive circuit arrangement for ignition of gas discharge light sources with series connected impedance,</li><li>Fig. 3 is a block diagram of the inventive circuit arrangement for generating a form suitable for powering gas discharge light sources, controlled operation alternating voltage,</li><li>Fig. 4 shows an embodiment of a one-bar self-oscillating converter, and</li><li>Fig. 5 shows another embodiment of the formed with a special unit for forming a power proportional signal, and with a controlled generator according to the invention the circuit arrangement.</li></ul>

p00341 as is seen from Fig., A Betreibswechselspannung to inputs of a transformer TR1 is applied, the high-voltage outputs are connected to a rectifier G1. The output of the rectifier G1 is guided via a current limiter B to a terminal A of a light source L. This at connecting terminal a is still a separation capacitor TC to one terminal of locking the operating current of the light source coil of the transformer TR1, while the other terminal b of the light source L to the other terminal of the operating current-locking coil of the transformer TR1 is connected directly.

p0035. The embodiment illustrated in Figure 1 operates in the following way:

p0036To the inputs of a transformer operating alternating voltage is switched, followed by Leerlaufbetriebsspanung appears at the terminals of the operating current-locking coil of the transformer TR1, which passes via the separating capacitor TC to the terminals a, b of the light source L. a high voltage transformed which the separating capacitor TC fed rectified via the current limiter B with charging current appears at the high voltage output of the transformer TR1. Since on the light source L, no current flows is on the separating capacitor TC recorded in to the capacity and the current-proportional voltage rise.

p0037Since the time constant of the voltage increase is several times the period time of the alternating voltage operation, the light source L will appear at the terminals a, b is a continuously increasing voltage, which is superimposed on the no-load operating voltage. When the composite voltage reaches the ignition voltage of the light source, lights the light source L and the idle operating voltage drops to the level of the internal voltage. By using a switch in the ignition circuit, the ignition voltage can be switched off and the output reaches no DC component. In a preferred embodiment, when the current limiter has a very high internal resistance, the gelangene to the output DC component is also negligible without interruption.

p0038In the embodiment according to FIG. 2, the dual function of serving for adjustment of the light source transformer was separated. For limiting the current used a series connected impedance I, on the other hand, the high voltage generated by the transformer TR2.

p0039Accordingly, an input terminal of Betriebswechelspannung is a terminal A of the light source L is connected via the impedance and the decoupling capacitor TC with, while the other input terminal of the AC operating voltage is connected directly to the other terminal b of the light source L.

p0040Between the common node of the impedance I and the separating capacitor and the other input terminal of the AC operating voltage, a primary coil of a transformer TR2 is connected, while the secondary coil of the transformer TR2 is connected to a rectifier G1, the output of which a current limiter B with a terminal b of the light source L is connected.

p0041The function of the embodiment shown in Fig. 2 differs from that shown in Fig. 1 that the voltage applied to the input AC operating voltage practically passes without a reduction to the light source L and this is reduced just after the ignition of the light source L to the value of the operating voltage and that the ignition voltage is generated by a separate transformer TR2. In another embodiment of transformer TR2 can be formed with a large internal impedance and thus partially or completely, the impedance of the current limiter B are installed in the transformer TR2.

p0042Both in Fig. 1 as well as in Fig. 2 illustrated embodiment can also be such be imagined that in any element of the ignition circuit or between the elements at any point an interrupt is inserted which is controlled by means of a comparator, which in some known manner (eg, by current monitoring, voltage monitoring) detects the ignition of the light source L and then also interrupts the circuit in known manner.

p0043The embodiments of the invention described above allow the ignition of light sources, which is a high ignition voltage demand (eg high-pressure gas discharge lamps) primarily when fed with a high frequency in a simple manner such that minimum losses and recorded no adverse reaction in the feed circuit ,

p0044In Fig. 3 is a block diagram of the inventive circuit arrangement is shown for producing a form suitable for powering gas discharge light sources, controlled AC operating voltage. In this circuit arrangement is to input terminals 1.2 a supply voltage U_on applied while the gas discharge light source can be connected to the outputs 27,28. The input terminal 2 is connected via an input 4 with a control unit S, whose output 7 is connected to an input 14 of a drive unit A.

p0045The output 17 of the drive unit A is connected to the terminal 22 of the transformer TR3. The outputs 25,26 of the transformer TR3 form the outputs 25,26 of the voltage converter at which the voltage U_out appears. The transformer TR3 is provided with a further output terminal 24 at which an input 20 of a feedback unit K is connected. An output 18 of the feedback unit K is connected to an input 12 of a control unit R, while an output 10 of Rege treatment unit R at an input 15 of the drive unit A and a further output 8 of the control unit R is connected to an input 6 of control unit S. The input terminal 1 is connected to a terminal 3 of the control unit S, a terminal 21 of the transformer TR3, and - if necessary - is connected to a terminal 11 of the control unit R and a terminal 13 of the drive unit A.

p0046The connections 5,9,16,19 of the individual units of the voltage converter according to FIG. 3 are performed on a combined node of the circuit, is guided on which the output terminal 23 of the transformer TR3.

p0047. The illustrated in Figure 3 embodiment of the invention works in the following way:

p0048The control unit S on using the drive unit A after a predetermined time at high speed, the excitation of the transformer TR3 from, and because over at the outputs 25,26 of the transformer TR3 connected cold light source can flow no current induced in all coils of transformer TR3 a reignition with large peak.

p0049The voltage appearing at the output terminal 24 of the transformer TR3 enters the feedback unit K via its input 20, which rectifies this voltage, filters, transforms, and forwards from their output 18 to the input 12 of the control unit R. The control unit R compares the gelangene at its input 12 signal with its inner reference signal and provides a signal proportional to the error signal on their outputs 8 and 10 to the input 6 of the control unit S and to the input 15 of the drive unit A. On effect of the signals increase or decrease the control unit S and the driving unit A, the duration of the next Erregungszyklusses. About the switched on effect of the firing light source flows a stream and takes from the transformer TR3 a significant achievement on and loaded the drive unit A in relation to the translation, thus a significant supply current.

p0050A signal proportional to the received power signal is supplied from the unit shown in Fig. 4 and Fig. 5 E to form a power signal proportional to or from the transistor T2, with this signal, the internal circuits of the control unit S in a known manner the operation factor of the regulate at the output 7 of the control unit S appearing control voltage.

p0051In Fig. 4 an embodiment of the application of the new procedures in self-oscillating converters-bar is illustrated. Fig. 4 shows, with the exception of the control unit S, a detailed circuit arrangement of the invention designed according to voltage converter, which circuit is a possible, one-bar self-oscillating embodiment.

p0052According to FIG. 4 is formed of the transformer TR3 having a primary coil L1, a feedback coil L2 and a secondary coil L3. The terminal 24 of the feedback coil L2 is guided through a diode D2 to the filter capacitor C2. That shown in Fig. 3 correspond to feedback unit K in the present embodiment, the diode D2 and the filter capacitor C2. The common point of the diode D2 and the filter capacitor C2 forms the output 18 of the feedback unit K.

p0053In the control unit R Fig. 4 according to a Zener diode D1 arranged whose one terminal to input 12 of the control unit R forms, while the other terminal of the Zener diode D1 forms the output 10 of the control unit R. At the output 10 of the corresponding input 15 of the drive unit A is connected in FIG. 3. The drive unit A is shown in FIG. 4 is formed with a transistor T1 whose base b1 connected to the output 10, the output 7 of the control unit S and via a capacitor C1 to an output 26 of the secondary coil L3. The collector c1 of the transistor T1 is connected to a terminal 22 of primary coil L1 of the transformer TR3, while the emitter E1 of the transistor T1 in the combined node of the filter capacitor C2, the other output terminal 23 of the feedback coil L2 and the output 16 of the drive unit is guided A , This united node simultaneously forms one output 28 of the voltage converter in the present embodiment, while the other Ausgung 27 forms the other output of the secondary coil L3 of the transformer TR3. The output terminal 24 of the feedback coil L2 is connected via a resistor R1 to the capacitor C1. One other terminal 21 of the primary coil L1 is guided to one input terminal of the voltage converter 1, whereas the other input terminal 2 is connected to the input 4 of the control unit S. The located in the control unit S unit E to form a power signal proportional with its terminals 29,30,31,32 and its output 33 in a corresponding rubbing result to the terminal 3, the input 4, the terminal 5, the input 6, and the output 7 of the control unit S out.

p0054. The Power illustrated in Figure 4 works in the following way:

p0055From the transformer TR3, a signal proportional to the restarting voltage signal of the feedback coil L2 removed, which is rectified by the diode D2 and filtered by the Fitlerkondensator C2. When this voltage exceeds the Zener diode through laßspannung D1, this initiates a negative-going current to the base B1 of the transistor T1. Thereby, the transistor T1 is biased in the negative direction, whereby the opening time is reduced, and the value of the re-generated U_CEV is reduced. The flow through the Zener diode D1 starting current at the same time increases the load of the transformer TR3 by the coupling to the feedback coil L2, thereby contributing to the limitation of the reignition. contributes to the scheme continues to be the at the common point of the resistance R1 and the capacitor C1, which are necessary for self-oscillating primary circuit, connected output 26 of the secondary coil L3 at through which positive feedback is realized and the number of turns of the secondary coil can be selected L3 low ,

p0056A further advantage can be ensured that the resistor R1 is formed with a negative temperature coefficient. By controlling the operating base current of the transistor T1, the service factor can be changed to a limited extent. While the ignition is increased to the input 6 of the controller S signal appearing at low re-ignition of the output at the output 7 base current and decreases at large reignition, whereby the return scheme is also supported.

p0057After ignition, the unit E regulates the formation of a power signal proportional to the base current of the transistor in erwünschtem measure.

p0058Referring to FIG. 5 shows a possible design of Steuerinheit S and their connection to other units is illustrated by this embodiment in more detail.

p0059The arranged in the control unit S unit E to form a power proportional signal is provided with a control transistor T2, whose emitter is e2 directly connected to the other input terminal 2, which is conducted through a current monitoring resistor R2 to the combined node. The base b2 of the control transistor T2 is connected to the common point of a voltage divider, wherein the one resistor R4 of the voltage divider with the combined circuit point is connected, while the other resistor R3 of the voltage divider is connected to an input terminal 1 of the voltage converter. The collector c2 of the control transistor T2 is connected to the input 34 of a trained variable operation factor generator G. A further input 36 of the generator G is guided at the output 8 of the control unit R, while an output 35 of the generator G - which is simultaneously the output 7 of the control unit S is formed - is connected to the input 14 of the drive unit A.

p0060. The embodiment illustrated in Figure 5 of the inventive circuit arrangement works in the following way:

p0061The excitation of the transformer TR3 is performed by the drive unit A according to the control voltage obtained from the output 35 of the generator G. During Zündzyklusses the generator G receives its input 6 from the output 8 of the control unit a the ratio of the re corresponding to the internal reference value control voltage, and adjusts accordingly, the excitation time.

p0062After the ignition of the generator G is controlled by its input 34 by the collector c2 of the control transistor T2 on the basis of comparison of the sum of the voltage across the resistor R2 (which is proportional to the via the resistor R2 flowing current is) and is proportional to the supply voltage voltage across which, consisting of the voltage divider resistors R3 and R4, mi t the forward voltage between the base and the emitter e2 b2. Based on the result of the comparison in the devoted signal changes of the generator G in a known manner the operation factor of appearing at its output 35 a control voltage.

p0063The inventive method and trained to carry out the process circuitry allow the light sources burn at low supply voltage and high supply voltage no losses, and the converter is not defective. The power control ensures in a wide temperature range Speisespannungs- and supplying the light source with adjusted power. One appears in the power control adverse effect is occurring at the current monitoring resistor R2 dissipation. This loss can be on the one hand by increasing the sensitivity of the unit E can be reduced to form a power proportional signal and on the other hand, compensated by the significant improvement of the functional properties of the circuit arrangement, since the power stabilization may be compared to the previously known solutions much better realized.