JP2008130572A - Electronic circuit for operating a plurality of gas discharge lamps by common voltage source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a uniform electric current distribution to all lamps without using any magnetic components, and only with the use of semiconductor components. <P>SOLUTION: The circuit enables to make operate a plurality of gas discharge lamps, especially, cold cathode discharge tubes, by a common voltage source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic circuit, particularly a semiconductor circuit, for operating a plurality of gas discharge lamps with a common voltage source.

  With the rapid development of liquid crystal display devices (LCDs), corresponding demands have also arisen for suitable broad-illumination light sources used as backlighting for these display devices. These specific requirements for backlighting include, among other things, emitting uniform light over the entire surface and high brightness display capability. At present, particularly gas discharge fluorescent lamps are used as these light sources. On the other hand, these lamps achieve white light (50-100 lumens / watt) highlight generation, while extensive experience in gas discharge fluorescent lamps is available in the lighting art. Substantial developments have also recently made progress with respect to light emitting diode (LED) emission, but the technology in this area is quite expensive and is therefore limited to smaller displays. More importantly, the linear shape of the gas discharge fluorescent lamp facilitates achieving a broad uniformity of light in comparison with a point light source such as an LED. In a flat screen display unit (LCD) based on the current prior art, there is a light diffusion plate behind the liquid crystal display unit, and a plurality of cold cathode discharge tubes are arranged in a regular form behind the light diffusion plate. And arranged in the horizontal direction. Small scale light homogenization is performed by a diffuser plate. For large-scale light homogenization, each fluorescent tube needs to emit the same amount of light. Sufficient light uniformity can be achieved by simply maintaining the individual lamp currents at the same value, since the partial differences already achievable in the lamp characteristics are completely negligible. For a longer effective lamp life, it is necessary to operate the lamp in alternating current. For maximum light emission, an operating frequency exceeding 10 kHz is required. In order to keep the magnetic element small, an operating frequency above 30 kHz is generally preferred. The upper limit of the operating frequency, especially the upper limit of the operating frequency in a long gas discharge lamp, is given by the parasitic capacitive current flowing from the lamp to the housing, so that the end of the gas discharge lamp arranged on the high voltage side emits lighter Is possible. Gas discharge lamps are typically supplied with a voltage of 1000 volts and have a current consumption of a few milliamps.

  Therefore, general technical problems arise when operating all gas discharge lamps with the same individual alternating current. An obvious technical solution is to provide each individual lamp with a high voltage transformer for itself and a regulation loop for itself, with a power supply for itself regulated for each lamp. It is. This solution works well, but is expensive due to the high cost of the components. Recent developments have specifically aimed at supplying power to all lamps from one central high voltage source. Due to the particular form of current / voltage characteristics of gas discharge lamps, in particular negative operating resistance at the operating point, several lamps cannot simply be connected in parallel. However, it is possible to operate several gas discharge lamps La in a common voltage source U˜ with the aid of a balanced transformer Tr. The traditional solution using cascaded balanced transformers is realized with the Ushijima balancer. Other improvements based on the same basic idea have recently been introduced as Newton Balancer, Chen Balancer and finally Gin Balancer (see FIG. 1) (eg, International Publication No. WO 2005/038828 (patents). Literature 1)). While these passive current balancing methods represent a significant advance, they still include the disadvantage of using a relatively large number of magnetic components, thereby using a significant percentage of the total cost of the lamp control circuit. It is out.

U.S. Pat. No. 7,042,171 discloses an electronic circuit that achieves uniform distribution of current in a gas discharge lamp La using only semiconductor components and no magnetic components. (FIG. 2). This patent applies the traditional idea of transistor-based current mirror technology directly to lamp current balancing. An important functional limitation of the circuit provided in US Pat. No. 7,042,171 results from the fact that the traditional circuit shown here only goes through the positive half-cycle, and further limitations are The collector current only when the lead channel (channel 1 in all figures of US Pat. No. 7,042,171), which also carries the total base current, is placed on the lamp having the maximum resistance at the relevant operating point. The equilibrium effect is obtained. However, the lamp having the maximum resistance at the operating point is not known in advance, and the lamp may exchange this role during further operation.
International Publication No. WO2005 / 038828 US Pat. No. 7,042,171

  It is an object of the present invention to operate a plurality of gas discharge lamps with a common voltage source, so that current distribution to the individual lamp branches (current balance) does not use any magnetic components and uses only semiconductor components. It is to provide a circuit that allows it to be fully achieved.

  This object is achieved by an electronic circuit having the features outlined in claim 1 or claim 8.

  Preferred embodiments and further advantageous features of the invention are listed in the dependent claims.

  A first preferred embodiment of the present invention is a circuit for operating a plurality of gas discharge lamps with a common AC voltage source for a defined current distribution to individual lamp branches, wherein each gas discharge lamp ( The present invention relates to a circuit in which an npn transistor and a pnp transistor are used as main components for a lamp branch). The input AC voltage through each lamp is separated into a positive half cycle and a negative half cycle using a diode. The positive half cycle is fed back to the AC voltage source via the collector-emitter portion of the npn transistor and the emitter resistor. The negative half cycle is fed back to the AC voltage source via the collector-emitter portion of the pnp transistor and the emitter resistor. The base terminals of all npn transistors are either directly electrically connected to each other or are connected via respective base resistors. The base terminals of all pnp transistors are either electrically connected directly to each other or are connected via respective base resistors. The base current of the interconnected transistors is derived from the lamp current of the gas discharge lamp (of the lamp branch), more precisely the gas discharge lamp with the lowest real impedance, and is equivalent to a Zener diode or Zener voltage. It flows over the potential barrier.

A preferred second embodiment of the present invention is a circuit for operating a plurality of gas discharge lamps with a common AC voltage source for a defined current distribution to individual lamp branches, wherein each gas discharge lamp ( It relates to a circuit in which two npn transistors or two pnp transistors are used as main components for a lamp branch). For each gas discharge lamp (each lamp branch), one half cycle of the input AC voltage is applied to the lamp and the first transistor through the first diode, and the other half cycle feeds the second diode. Via the lamp and the second transistor. The base terminals of all the first transistors are electrically connected directly to each other or are connected via respective base resistors. Similarly, the base terminals of all the second transistors are electrically connected directly to each other or are connected via respective base resistors. The base current of the interconnected transistors is derived from the lamp current of one gas discharge lamp (of one lamp branch), more precisely the gas discharge lamp with the lowest real impedance, and the Zener diode or Zener voltage. It flows over the potential barrier of the equivalent potential.

  In one embodiment of the present invention, each transistor generates a potential difference between a base terminal and a collector terminal, and has a high impedance when the potential difference between both ends is lower than a specific voltage potential. It is preferable to have an element or circuit component having a low impedance when higher than the potential. Alternatively, a single common element or circuit component that generates a potential difference may be provided for the first group of transistors interconnected at the base. Similarly, a single common element or circuit component that generates a potential difference can be used for a second group of transistors interconnected at the base.

  The base terminal of each transistor can be connected directly to the rest of the circuit or can be connected through a resistor. However, the base terminal can also be connected to other parts of the circuit via a resistor and a capacitor connected in parallel to the resistor.

  In order to balance the charge in each lamp current branch associated with the gas discharge lamp, preferably a capacitor can be connected in series with the associated gas discharge lamp.

  The base current for the transistors interconnected at the base can also be supplied from an auxiliary voltage source via an additional transistor whose base terminal is connected to the element generating the potential difference.

  On the other hand, the base current for the transistors interconnected at the base can be supplied using an additional circuit in the form of a multiplying current mirror. By the additional circuit, a small proportion of the emitter current of the lamp current branch is fed back to the base terminal until the first transistor enters the saturation region. The additional circuit maintains a stabilized circuit in this state.

  FIG. 3 shows a preferred first embodiment of the present invention in which an npn transistor Qp and a pnp transistor Qn are used as main components for each gas discharge lamp La (lamp branch). In general, each lamp branch or channel has two diodes Dp and Dn that separate the following subcircuits: an alternating current (AC) voltage source U ~ applied across the lamp La into positive and negative current half cycles. have. The alternating voltage source U is supplied by a high voltage source such as a high voltage transformer. The positive half cycle passes through the npn transistor Qp and the negative half cycle passes through the pnp transistor Qn. Both positive and negative half cycles are fed back to the voltage source via an emitter resistor Re common to the two transistors Qp, Qn. In some applications, it may be advantageous to provide a separate emitter resistor for each transistor Qp and Qn. The bases of all npn transistors Qp are connected to each other (p current mirror). Similarly, the bases of all pnp transistors Qn are connected to each other (n current mirror). The base terminal of the npn transistor Qp is connected to the collector terminal of the same transistor Qp using a Zener diode Zp. The base terminal of each pnp transistor Qn is connected to the collector terminal of the same transistor Qn using a Zener diode Zn. All zener diodes Zp and Zn have the same nominal zener voltage, typically in the range of 100-300 volts. These Zener diodes Zp, Zn are extremely important to the function of the circuit because the current isolation effect of the circuit still exists even if the channel with the maximum impedance is not known or changes during operation. is there. A conventional current mirror circuit as proposed in US Pat. No. 7,042,171 (FIG. 4 of the publication) is such that the channel with the maximum impedance is the lead channel (the channel in the drawing included in this patent publication). Realize current distribution only when used as 1). This non-negligible functional limitation is overcome by the use of a Zener diode according to the present invention.

  The technical function shown in FIG. 3 can be described as follows. That is, as long as the voltage drop between the collectors and emitters of the transistors Qp and Qn is lower than the Zener voltages of the Zener diodes Zp and Zn, all the transistors are blocked because no base current flows. Here, when the voltage of the common lamp supply voltage source U to half-cycle voltage rises, the Zener voltage first reaches the channel with the lamp La of the minimum impedance, and the associated Zener diode Zp or Zn is turned on, respectively. Become. Since the bases of all npn or pnp transistors Qp and Qn are connected to each other, all interconnected transistors Qp and Qn are triggered via the first conducting Zener diodes to establish the transistor base. Current begins to flow. Thus, in this way, the first Zener diodes that become conductive are transistors whose bases are interconnected, each with one Zener diode in the positive half cycle and one Zener diode in the negative half cycle. Trigger all of the bases. At this stage, the collector voltage in the other ramp channel with high resistance is slightly lower than the zener voltage. Because of the same base voltage (because the base is directly connected) and the same emitter resistance value, the emitter current values in all transistors Qp or Qn interconnected at the base are the same. The same applies to the collector current as long as no transistor enters saturation, i.e. neither transistor is fully switched on, and so is the lamp current. In this case, the lamp current is maintained at the same value (balanced) by the circuit. As soon as the voltage difference between the collector and emitter in one of the channels approaches zero, the circuit loses its ability to distribute the current evenly. This state is more likely to occur as the level of the Zener voltage is lower and the tolerance of the lamp characteristics is larger. By selecting the zener voltage at a sufficiently high level, a very stable and reliable current distribution can be achieved. However, as the Zener voltage level increases, the energy loss in the circuit also increases. This means that during circuit design, the Zener voltage level needs to be selected based on lamp operating parameters and tolerances.

  In the embodiment according to FIG. 3, the half-cycle base current for all transistors is supplied by one ramp channel, and therefore the current through the lamp in this channel is reduced. The base current of conventional transistors is typically as low as 1 / 100th of the collector current, but will not present any problem for balanced current distribution unless too many channels are used. In the circuit according to FIG. 3, two Zener diodes are required for each ramp channel.

  In a further preferred embodiment of the invention according to FIG. 4, the number of Zener diodes Zp and Zn required can be reduced to a total of two, one of which is positive for the supply voltage source U˜. The other half is for the negative half cycle. However, instead of the thus omitted zener diode, several conventional diodes are required. The functionality of the basic circuit of FIG. 3 does not change in the variant shown in FIG. 4, but this variant provides a structural advantage to the circuit, and ordinary diodes are less expensive than zener diodes. As such, it also provides a cost advantage.

  For each channel, four diodes Dp, Dpz and Dn, Dnz are required. The positive half-cycle current from the supply voltage source U is fed back to the voltage source via the gas discharge lamp La, the diode Dp, the transistor Qp and the resistor Re. For the negative half cycle, the current is fed back to the voltage source via the lamp La, the diode Dn, the transistor Qn and the resistor Re. The zener diode Zp for the positive half cycle is triggered via the diode Dpz of each channel, and the zener diode Zn for the negative half cycle is triggered via the diode Dnz. All channel diodes Dpz form a logical OR circuit, and so does diode Dnz. The voltage applied across the logic diode network must overcome the voltage level of the Zener diode Zp or Zn (the Zener voltage level) plus the respective voltage drop at the respective diode Dpz or Dnz. The channels with the maximum voltage, ie the lamp with the lowest impedance, and therefore the lamp with the lowest voltage drop in the lamp, are switched through the zener diodes Zp and Zn, respectively, and are respectively base to the transistor Qp or Qn. Provides current.

  In the embodiment of the circuit shown in FIG. 4, even if the lamp currents are no longer the same, for example, the collector-emitter voltage drop of either transistor Qp or Qn approaches zero (saturation region), respectively. The voltage drop across the resistor Re is always the same.

  By introducing an additional base resistor Rb to the transistors Qp and Qn according to FIG. 5, current sharing disturbances can also be observed by the voltage drop across the emitter resistor. As long as the circuit function is "normal", i.e. no transistor is operating in the saturation region, the base current is correspondingly small and only a very small voltage drop occurs in the base resistor Rb. However, as soon as the transistor enters saturation and more current flows to the base, a larger voltage drops in the base resistor Rb. The base potential of this transistor operating in the saturation region is therefore no longer the same as the base potential of the other transistors. When the base potential changes, the current flowing through the emitter resistor Re changes and therefore the voltage drop also changes. This voltage drop can be measured. The measurement result is advantageous for the subsequent monitoring of the circuit. Since the base resistor Rb does not impair the distribution of the supplied current, the base resistor Rb is not sufficiently larger than the emitter resistor Re. The dynamic characteristics of the circuit can be improved by a capacitor Cb in parallel with each base resistor Rb.

  A further embodiment of a circuit for distributing current is shown in FIG. 6 and includes a balancing capacitor Cs connected in series with each of the lamps La. Capacitor Cs ensures that the amount of positive and negative charges transmitted through the lamp are exactly the same, thus allowing the maximum useful life of the lamp to be maximized. Since the capacitor Cs passes only the AC component, this ensures that the amount of charge passing through the capacitor Cs in one direction and the amount of charge passing through the capacitor Cs in the other direction are exactly the same.

  All of the circuit variations shown in FIGS. 3 to 6 do not require any additional external voltage source other than voltage source U˜ because the base currents of transistors Qp and Qn are derived from the lamp current. Has the advantage. As long as the required base current is small compared to the lamp current, no serious disturbance of current distribution will appear. However, if the number of lamps La increases and / or the current amplification of the transistor decreases, this characteristic means a limitation.

  This limitation can be overcome by the auxiliary circuit element shown in FIG. 7 having transistors TBp and TBn. Transistors TBp and TBn function as current amplifiers. The base current for the transistors Qp and Qn in the lamp branch is now derived from two auxiliary voltage sources (V +, V−). Only the residual current reduced by the current amplification of the transistor TBp or TBn, respectively, now flows through the Zener diode Zp or Zn, respectively, so that this effectively causes the base currents of the transistors Qp and Qn to be the current of the lamp current. Stop affecting distribution.

  In another preferred embodiment, a resistor is connected between the base and emitter terminals of transistor TBp to increase the interference resistance, and a capacitor is connected in parallel with this resistor. The same auxiliary circuit element can also be used for transistor TBn.

  All the embodiments described so far with reference to FIGS. 3 to 7 of the current distribution circuit require a compromise in the selection of the voltage levels of the zener diodes Zp and Zn. Higher voltage levels increase the tolerance range of the circuit, but also increase energy loss. Experience has shown that the Zener voltage level required for reliable distribution of current drops as the lamp La heats up. Thus, the Zener voltage level can be lowered after the lamp heating phase, which allows the lamp to operate at a high level of efficiency. Similar considerations can be applied to changing environmental temperatures. To maximize efficiency, the circuit element therefore needs to function like a Zener diode, but its Zener voltage must be dynamically adapted to the actual operating conditions of the lamp. This type of operation is achieved by the following circuit elements shown in FIG. 8 and described below. FIG. 8 is based on the basic circuit according to FIG.

  The transistors Q1 and Q2 and the similar Q3 and Q4 shown in FIG. 8 form a multiplication current mirror circuit, and feed back a small amount of the emitter current of the balanced circuit to the common base terminal of the transistor Qp or Qn, respectively. The ratio of the feedback current can be determined by the values of resistors R1 and R2. If the feedback current is smaller than the total base current of the interconnected transistors Qp or Qn, respectively, the Zener diode Zp or Zn must now carry part of the base current for the transistor Qp or Qn, respectively. Since there are only new circuit elements, the respective loads on the Zener diodes Zp or Zn are reduced. However, if the design of a current mirror circuit having characteristics (loop amplification degree> 1) such that the feedback current exceeds the common base current required by each of the interconnected transistors Qp or Qn is determined, each npn Until one transistor of transistor Qp and one transistor of each pnp transistor Qn operate in the saturation region, the operating point drift is fixed due to positive feedback, and until each loop gain becomes equal to 1 again, Conduction is conducted so that the current amplification level drops greatly. This ensures that the voltage drop in each transistor Qp or Qn almost disappears under each operating state. The voltage drop in the other transistors is just large enough for the same current to flow through each channel. This results in the circuit automatically self adjusting the efficiency to the maximum level.

  The functionality of the current mirror circuit will now be described based on the circuit elements of the lamp branch that function for the positive half cycle of the input alternating current. The functionality of the circuit elements that function for the negative half cycle of the input alternating current is the same as that of the positive half cycle. Transistor Q1 forms a current mirror and emitter current whose emitter current is determined by the value of resistor R1. If the resistor R1 has the same value as the resistor Re in the lamp branch, the current flowing through the resistor R1 is also the same value as the current flowing through the resistor Re. If a different value of resistor R1 is used, a multiplication current mirror is obtained in which the emitter current is only a third to a tenth of the lamp branch current, for example. Transistor Q2 also forms another current mirror that again substantially reflects the collector current of transistor Q1 depending on resistor R2. Eventually, the current from transistor Q2 is supplied to the node at the base of transistor Q1, and the current from transistor Q2 is proportional to the lamp current in each lamp branch (a factor such as 0.1 or 0.01 for the lamp current). Multiplication). In accordance with the present invention, the current mirror is designed such that the base current of transistor Q1 is somewhat larger than the common base current for transistor Qp supplied via zener diode Zp, thereby providing a Zener diode. The current flowing through Zp becomes zero. At this point, the circuit begins to drift and becomes unstable, and the current mirror becomes unstable to feed back more current than is actually needed to stop the current through the Zener diode Zp. Become. As a result, the base potential at the interconnection base of transistor Qp rises and transistor Qp begins to conduct. The circuit continues to be in that state, and transistor Qp turns on gradually, and this state continues until one of transistors Qp enters saturation. The process becomes more stable when the transistor that enters saturation draws more strongly the current drawn by the current mirror. At this point, one of the transistors Qp is fully conductive (enters saturation) and has a very low impedance. The other transistors Qp in the group have a smaller degree of conduction and a large resistance value between the collector and the emitter. This state is essential to improve the level of circuit efficiency. For transistor Qp entering saturation, the voltage drop between the collector and emitter is minimal and somewhat higher for other transistors. The power loss in transistor Qp is thereby minimized.

  Thus, the (multiplier) current mirror has the same effect as a Zener diode whose voltage level is precisely adjusted so that only transistor Qp is just close to saturation. When the effect of the current mirror circuit becomes significant, no current flows through the Zener diode after that point, so the Zener diode Zp is no longer needed immediately. However, in order to start the process, an initial current supplied via the Zener diode Zp is required. However, as soon as the process is started, the zener diode Zp becomes unnecessary. The same description and functionality applies to the Zener diode Zn and the associated current mirror formed by transistors Q3 and Q4.

  In the above-mentioned possible application of the circuit according to the invention, the positive half cycle of the lamp current is transmitted via the npn transistor Qp and the negative half cycle is transmitted via the pnp transistor Qn. However, it is possible to modify the circuit so that only npn transistors or only pnp transistors are used.

  In FIG. 9, npn transistors To1,. . . , Presents a circuit for balancing current using only Ton. If the polarity of all diodes is reversed, a similar circuit is possible for npn transistors. npn transistors To1,. . . , Ton is advantageous because npn transistors are generally less expensive than pnp transistors.

  In FIG. 9, the positive half cycle of the input AC voltage source U˜ (explained by way of example for the first lamp branch) feeds back through the transistor To1 via the diode Do1 and the transistor Tu1 via the lamp La. And passes through the resistor Re and returns to the voltage source. At the same time, the positive half cycle reaches the zener diode Zu via the diode Dv1. The negative half cycle of the input AC voltage source U˜ returns through the transistor Tu1 via the diode Du1, and returns to the voltage source via the transistor To1 and the resistor Re via the lamp La. At the same time, the negative half cycle reaches the zener diode Zo via the diode Dp1. The other functionality of the circuit according to FIG. 9 corresponds to the circuit of FIG.

  FIG. 10 shows the circuit of FIG. 9 with an additional amplifier circuit for Zener diode current. The amplifier circuit is constituted by two transistors TBp respectively associated with zener diodes Zo and Zu, each operated by an auxiliary voltage source V +. The base current for the lamp branch transistors Tu1 and To1 is drawn here from the auxiliary voltage source V +. The functionality of the amplifier circuit is described in connection with FIG.

  FIG. 11 shows the auxiliary circuit element of FIG. 8 applied to the circuit of FIG.

  The additional circuitry used in FIGS. 10 and 11 to improve current distribution and efficiency levels can also be used in other advantageous embodiments simultaneously (together with each other).

FIG. 1 schematically shows a circuit for balancing currents using a balanced transformer (prior art). It is a figure which shows roughly the circuit for balancing an electric current using a semiconductor circuit (prior art). FIG. 2 schematically shows an embodiment according to the invention of a circuit for balancing currents using a semiconductor circuit. FIG. 3 is a modified embodiment of a circuit for balancing currents using a semiconductor circuit, wherein a single Zener diode is used for each positive and negative current branch. FIG. FIG. 4 is a modified embodiment of a circuit for balancing current using a semiconductor circuit, in which a transistor base resistor is used and a capacitor connected in parallel to the base resistor can also be used. It is a figure showing an embodiment roughly. FIG. 5 schematically illustrates an embodiment with respect to FIG. 4 of a circuit for balancing current using a semiconductor circuit, wherein a capacitor for balancing the charge of the lamp current is used. is there. FIG. 5 schematically illustrates an embodiment with respect to FIG. 4 of a circuit for balancing current using a semiconductor circuit, wherein an auxiliary voltage source for supplying a base current is used. FIG. 6 schematically illustrates a further embodiment of a circuit for balancing current using a semiconductor circuit, wherein an additional current mirror circuit for supplying a base current is used. FIG. 6 schematically illustrates a further embodiment of a circuit for balancing current using a semiconductor circuit, in which only transistors of the same type (npn) are used. FIG. 10 schematically illustrates an embodiment modified with respect to FIG. 9 of a circuit for balancing current using a semiconductor circuit, wherein an auxiliary voltage source for supplying a base current is used. FIG. 10 schematically illustrates an embodiment with respect to FIG. 9 of a circuit for balancing current using a semiconductor circuit, wherein an additional current mirror circuit for supplying a base current is used. is there.

Claims (14)

An electronic circuit that regulates and distributes current to individual lamp branches in order to operate a plurality of gas discharge lamps (La) with a common AC voltage source (U).
a: The alternating current flowing through each of the lamps (La) is separated into positive and negative half cycles by a diode (Dp, Dn),
b: The positive half cycle is fed back to the AC voltage source via the collector-emitter part of the npn transistor (Qp) and the emitter resistor (Re),
c: The negative half cycle is fed back to the AC voltage source via the collector-emitter part of the pnp transistor (Qn) and the emitter resistor (Re),
d: the base terminals of all npn transistors (Qp) are either electrically connected directly to each other or to each other via individual base resistors (Rb);
e: The base terminals of all pnp transistors (Qn) are electrically connected directly to each other or to each other via individual base resistors (Rb),
f: A common base current for the transistor (Qp; Qn) derived from the lamp current of the gas discharge lamp (La) is applied to a potential barrier having a potential equivalent to a Zener diode (Zp; Zn) or a Zener voltage. Triumph and flow,
An electronic circuit characterized by that.   Each of the transistors (Qp; Qn) generates a potential difference between a base terminal and a collector terminal, and has a high impedance when the potential difference between both ends thereof is lower than a specific voltage potential, and a low impedance when higher than the specific voltage potential. 2. The electronic circuit according to claim 1, comprising an element (Zp; Zn) or a circuit element including   For the first group of transistors (Qp) interconnected at the base, a single common element (Zp) or circuit element that generates a potential difference is used, and similarly the transistors interconnected at the base The electronic circuit according to claim 1, wherein a single common element (Zn) or a circuit element that generates a potential difference is used for the second group of (Qn).   The base terminal of each transistor (Qp; Qn) is connected to the other part of the circuit via a resistor (Rb) or a resistor (Rb) to which a capacitor (Cb) is connected in parallel. The electronic circuit according to claim 1, wherein the electronic circuit is provided.   A capacitor (Cs) is connected in series with the gas discharge lamp to balance the charge in each lamp current branch associated with the gas discharge lamp (La). The electronic circuit as described in any one.   The base current for the transistors (Qp; Qn) interconnected at the base is supplied by an auxiliary voltage source (V +; V−) via an additional transistor (TBp; TBn), which generates a potential difference. 6. The electronic circuit according to claim 1, wherein a base terminal is connected to the element (Zp; Zn).   Using an additional circuit in the form of a multiplying current mirror (Q1, Q2, Q3, Q4), a small percentage of the emitter current of the lamp current branch is fed back to the base terminal of each transistor (Qp; Qn). The electronic circuit according to claim 1, wherein the electronic circuit is provided. An electronic circuit that regulates and distributes current to individual lamp branches in order to operate a plurality of gas discharge lamps (La) with a common AC voltage source (U).
a: For each gas discharge lamp, one half cycle of the input AC voltage is applied to the lamp (La) and the first transistor (Tu) via a first diode (Do), the other A half cycle is applied to the lamp (La) and the second transistor (To) via a second diode (Du),
b: the base terminals of all the first transistors (Tu1, ..., Tun) are electrically connected directly to each other or to each other via individual base resistors;
c: the base terminals of all the second transistors (To1,..., Ton) are electrically connected directly to each other or to each other via individual base resistors;
d: a common base current of the transistors (To1, ..., Ton; Tu1, ..., Tun) derived from the lamp current of the gas discharge lamp (La) is a zener diode (Zo; Zu) or Overcoming the potential barrier with a potential equivalent to the Zener voltage,
An electronic circuit characterized by that.   Each of the transistors (To1,..., Ton; Tu1,..., Tun) generates a potential difference between the base terminal and the collector terminal, and has a high impedance when the potential difference between both ends is lower than a specific voltage potential. 9. An electronic circuit according to claim 8, further comprising an element (Zo; Zu) or a circuit element having a low impedance when higher than the specific voltage potential.   For the first group of the transistors (To1,..., Ton) interconnected at the base, a single common element (Zo) or circuit element that generates a potential difference is used, as well 9. A single common element (Zu) or circuit element for generating a potential difference is used for the second group of interconnected transistors (Tu1,..., Tun). The electronic circuit according to.   A base terminal of each of the transistors (To1,..., Ton; Tu1,..., Tun) is connected to a resistor (Rb) via a resistor (Rb) or a capacitor (Cb) connected in parallel. 11. The electronic circuit according to claim 8, wherein the electronic circuit is connected to another part of the circuit via   12. A capacitor (Cs) connected in series with the gas discharge lamp in order to balance the charge in each lamp current branch associated with the gas discharge lamp (La). The electronic circuit as described in any one.   Base current for the transistors (To1, ..., Ton; Tu1, ..., Tun) interconnected at the base is supplied by an auxiliary voltage source (V +) via an additional transistor (TBp) and the additional 13. The electronic circuit according to claim 8, wherein a base terminal of the transistor is connected to an element (Zo; Zu) that generates a potential difference.   Using an additional circuit in the form of a multiplying current mirror (Q1, Q2, Q3, Q4), a small proportion of the emitter current of the lamp current branch is reduced to each of the transistors (To1,... Ton; Tu1 14. The electronic circuit according to claim 8, wherein the electronic circuit is fed back to a base terminal.

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