JPH10162974A - Circuit device for lighting low-pressure discharge lamp with low voltage power source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit device for lighting a low-pressure discharge lamp with a low-voltage power source, capable of lighting the low-pressure discharge lamp even with a power source having extremely low supply voltage, especially with supply voltage of only 2.5V. SOLUTION: A circuit device is formed as a single end type flyback converter having a switching transistor T and a transformer TR having one primary winding Nl and two secondary windings N2, N3 as a main component. In order to assure gentle ignition and long life of a lamp, at least one filament E2 of electrode filaments of a low-pressure discharge lamp L is pre-heated before ignition. Heating voltage for pre-heating the electrode filament E2 is decided by the sum of the partial voltage in the normal direction of the primary winding N1 and the partial voltage in the normal direction of a feedback winding N3, only by mainly the induction voltage of the feedback winding, or by voltage in the forward direction of the feedback winding and battery voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit arrangement in which the circuit arrangement is formed as a single-ended flyback converter having a transistor and a transformer, wherein the primary winding of the transformer is connected in series with the switching section of the transistor and comprises A second terminal having a second secondary winding and a second secondary winding;
, Each having a first and a second terminal, the first secondary winding being used to drive a control electrode of the transistor, and a first terminal of the primary winding. For lighting a low voltage discharge lamp with a low voltage power supply connected to a second terminal of a first secondary winding, and the circuit device is formed as a single-ended flyback converter having a transistor and a transformer Wherein the primary winding of the transformer is connected in series with the switching section of the transistor and has first and second terminals, and the transformer has a first secondary winding and a second secondary winding. , These are respectively the first and second
Circuit device for lighting a low voltage discharge lamp with a low voltage power supply having a first secondary winding used to drive the control electrode of the transistor, and a single circuit device having a transistor and a transformer Formed as an end-type flyback converter, the primary winding of the transformer is connected in series with the switching section of the transistor and has first and second terminals, the transformer comprising a first secondary winding and a second A secondary winding, each having a first and a second terminal, the first secondary winding being used to drive a control electrode of the transistor, the first secondary winding having a first terminal; The present invention relates to a circuit device for lighting a low-pressure discharge lamp with a low-voltage power supply having two terminals connected to a first pole of the low-voltage power supply.

[0002]

2. Description of the Related Art A circuit arrangement of this kind is known, for example, from EP-A-0 655 880. The circuit arrangement described in this publication is formed as a single-ended flyback converter with a switching transistor and a transformer. The transformer has two secondary windings, of which the first secondary is used to drive the control electrode of the switching transistor and the second secondary is the ignition for the low-pressure discharge lamp And to generate a lighting voltage. The primary winding of the transformer is connected in series with the switching section of the transistor.
In this circuit arrangement, a first terminal of a first secondary winding is connected to a first lamp electrode via a first diode, while a second terminal of the first secondary winding is connected to a primary terminal. It is connected to a winding and is further connected to a heatable second lamp electrode via a second diode. This circuit arrangement enables the operation of a low-pressure discharge lamp with a 5V power supply.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-voltage discharge lamp which can operate a low-voltage discharge lamp with a supply voltage of only 2.5 V, even with a power supply having an extremely low supply voltage. It is to provide a circuit device for lighting.

[0004]

SUMMARY OF THE INVENTION According to the invention, the circuit arrangement is formed as a single-ended flyback converter having a transistor and a transformer, the primary winding of the transformer being provided in the switching section of the transistor. Connected in series and having first and second terminals, the transformer having a first secondary winding and a second secondary winding, each having first and second terminals, A first secondary winding is used to drive a control electrode of the transistor, and a first terminal of the primary winding is connected to a low voltage power supply connected to a second terminal of the first secondary winding. In a circuit arrangement for lighting a discharge lamp, a second terminal of a primary winding is connected to a second secondary electrode via a second lamp electrode and a second diode capable of providing a preheating voltage of the low-pressure discharge lamp. Being connected to the first terminal of the wire Therefore, it is resolved.

Further, according to the invention, the circuit arrangement is formed as a single-ended flyback converter having a transistor and a transformer, the primary winding of the transformer being connected in series with the switching section of the transistor. And first and second terminals, the transformer having a first secondary winding and a second secondary winding, each having first and second terminals, and a first secondary winding. A circuit arrangement for lighting a low voltage discharge lamp with a low voltage power supply wherein a secondary winding is used to drive a control electrode of a transistor.
Is connected to the second terminal of the first secondary winding via a diode and the preheatable lamp electrode of the low-pressure discharge lamp.

[0006] Furthermore, according to the present invention, the circuit arrangement is formed as a single-ended flyback converter having a transistor and a transformer, the primary winding of the transformer being connected in series with the switching section of the transistor. And first and second terminals, the transformer having a first secondary winding and a second secondary winding, each having first and second terminals, and a first secondary winding. A second winding is used to drive the control electrode of the transistor, and a second terminal of the first secondary winding is used to light the low voltage discharge lamp with the low voltage power supply connected to the first pole of the low voltage power supply In a circuit arrangement, the first terminal of the first secondary winding is connected to the second pole of the low-voltage power supply via a diode and a preheatable lamp electrode of the low-pressure discharge lamp. You.

[0007] Particularly advantageous embodiments of the invention are described in claim 4 and subsequent claims.

The circuit arrangement according to the invention is formed as a single-ended flyback converter having a switching transistor and a transformer with one primary winding and two secondary windings. The primary winding of the transformer is connected in series with the switching section of the transistor. The first secondary winding is used to drive the control electrode of the switching transistor, while the ignition and operating voltage for the low-pressure discharge lamp is generated by the second secondary winding of the transformer.

In the case of the first embodiment of the invention, the first terminal of the primary winding is connected to the second terminal of the first secondary winding. Furthermore, in the case of this first embodiment, according to the invention, the second terminal of the primary winding is connected via a second lamp electrode and a second diode, which can provide the preheating voltage of the low-pressure discharge lamp. Connected to the first terminal of the first secondary winding. This gives the second lamp electrode a sufficiently high heating voltage during its preheating. This is because, according to the wiring of the transformer winding according to the present invention, the series circuit composed of the second lamp electrode filament and the second diode has a voltage of the primary winding and a voltage of the first secondary winding. Is applied. That is, the heating voltage for heating the lamp electrode is mainly determined by the flyback voltage at the primary winding and the induced voltage of the first secondary winding added to the flyback voltage.

In a second embodiment of the invention, according to the invention, the first terminal of the first secondary winding is connected to the first terminal via a diode and a preheatable electrode filament of the low-pressure discharge lamp. Connected to the second terminal of the secondary winding. In this second embodiment, the first secondary winding is used for generating a drive signal for the control electrode of the switching transistor and for heating the second electrode filament of the low-pressure discharge lamp. Also used to generate voltage. The number of turns of the first secondary winding is greater than the number of turns of the primary winding in this embodiment. Thus, the first secondary winding is driven by the pre-heated electrode filament on the basis of an induced voltage of a magnitude corresponding to the number of windings, with respect to the primary winding of the circuit device according to EP-A-0 655 880. Can be supplied with a higher heating voltage than the heating voltage supplied by.

[0011] In a third embodiment of the invention, the second terminal of the first secondary winding is connected to the first pole of the low voltage power supply. Furthermore, according to the invention, the first terminal of the first secondary winding is connected to the second pole of the low-voltage power supply via a diode and a preheatable lamp electrode of the low-pressure discharge lamp. With such a wiring according to the present invention, during the electrode preheating phase, the induced voltage of the first secondary winding and the supply voltage of the power supply are added, thereby forming a series circuit composed of a diode and a preheatable electrode filament. Can be used as a heating voltage for preheating the electrode filament. This usable heating voltage is greater than the supply voltage of the power supply. The electrode preheating phase occurs in this embodiment in the conducting phase of the switching transistor of the single-ended flyback converter, contrary to the first two embodiments.

In order to ensure a reliable ignition of the low-pressure discharge lamp, it is advantageous if the circuit arrangement according to the invention has one terminal for an auxiliary ignition electrode of the lamp. It is advantageous if this terminal is connected to the second secondary winding via a capacitor.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on three excellent embodiments.

FIG. 1 shows an excellent first embodiment of the circuit arrangement according to the invention.
1 schematically shows a circuit diagram of an embodiment of the present invention. This circuit device is used for lighting a hand lamp provided with a small U-shaped fluorescent lamp. The circuit arrangement operates on the principle of a single-ended flyback converter, and comprises a transistor T as its main components, a transformer comprising one primary winding N1, two secondary windings N2, N3 and a ferrite core. T
R. A battery or accumulator, for example, two minyon batteries supplying a supply voltage of about 2.5 V is used as power supply. A relatively large-capacity electrolytic capacitor C1 is connected in parallel with the power supply. This input capacitor C1 is charged to the battery voltage and prevents the internal impedance, which increases with discharge of the battery, from adversely affecting the lamp lighting, ie the lamp brightness does not drop too much with increasing discharge of the battery.

The capacitor C1 or the positive pole of the power supply is on the one hand the winding start of the primary winding N1 of the transformer TR, on the other hand the winding end of the first secondary winding N3 and the first of the capacitor C4. Connected to terminal. This capacitor C
The second terminal 4 is connected to both short-circuited terminals of the first electrode filament E1 of the low-pressure discharge lamp L. This first electrode filament E1 is further connected to the cathode of the first diode D1. The anode of this diode D1 is connected on the one hand to the winding end of the second secondary winding N2 and on the other hand to the first terminal of the auxiliary ignition capacitor C6. The second terminal of the starting auxiliary capacitor C6 is connected to the starting auxiliary electrode Z of the low-pressure discharge lamp L. This ignition auxiliary electrode Z is provided outside the glass bulb or is a reflector made of a conductive material or provided with a conductive coating and partially surrounding the lamp.

The terminal end of the primary winding N1 is led to the collector terminal of the switching transistor T, while the emitter terminal of the transistor T is connected to the input capacitor C1 or the negative pole of the power supply. The base terminal of the transistor T is a low-pass filter R1, C2 and an adjustable resistor R
2 to the winding start of the first secondary winding N3 of the transformer. A capacitor C3 is connected in parallel with the adjustable resistor R2. The low-pass filter capacitor C2 is located in parallel between the base and the emitter of the transistor T. A capacitor C5 for reducing the occurrence of power loss is arranged in parallel between the collector and the emitter of the transistor T.

Further, the winding end of the primary winding N1 is connected to the winding start of the second secondary winding N2 and the first terminal of the second electrode filament E2 of the low-pressure discharge lamp L.
The second terminal of the second electrode filament E2 is connected to the anode of the second diode D2. This second
Of the diode D2 is connected to the winding start end of the first secondary winding N3. Symbol S represents a switch for turning on and off the circuit device.

This circuit device operates based on the functional principle of a single-ended flyback converter. During the conducting phase of the transistor T, the transformer TR stores energy on the primary side and releases this energy to the lamp L via the secondary winding N2 during the cut-off phase. Switching transistor T
Is controlled by the first secondary winding N3 and the components R2, C3, which are fed back to the primary winding N1.

When the switch S is closed, a current flows through the feedback winding N3 of the transformer TR to turn on the transistor T, and this current flows between the primary winding N1 and the conducting collector-emitter of the transistor T. Increase the current. When the current flow through the primary winding N1 reaches a maximum value, a reverse polarity voltage called a flyback voltage is induced in the feedback winding N3, which turns off the transistor T. After the disappearance of the induction event, the transistor T is connected to the primary winding N1.
Is turned on again by feedback between the feedback winding N3 and the feedback winding N3.
This starts a new switching cycle.

When the transistor T is switched off, an induced voltage is generated in the second secondary winding N2 which also generates the necessary ignition or operating voltage for the lamp L. The diode D1 and the slight resistance of the still cold lamp electrode filament E2 prevent the immediate ignition of the lamp L. First, the heating current supplied from the primary winding N1 and the feedback winding N3 flows through the second electrode filament E2 of the lamp L and the diode D2. During the electrode preheating phase, in the cutoff phase of the switching transistor T, the second electrode filament E2
That is, a voltage obtained by subtracting only the voltage drop at the diode D2 from the sum of the partial voltages dropped to the primary winding N1 and the feedback winding N3 is applied to both terminals of the electrode filament E2. That is, during the preheating phase of the electrode filament E2, the flyback voltage of the first secondary winding N3 and the partial voltage generated in the primary winding N1 due to self-inductance are added to serve as a heating voltage for the electrode filament E2. Is polarized. As the heating of the electrode filament E2 increases, its resistance increases, so that the voltage induced in the secondary winding N2 likewise increases, and a firing voltage of about 700 volts is obtained between the lamp electrodes E1, E2. , The lamp L is ignited, so that the discharge section becomes electrically conductive. The electrode heating phase extends over a number of switching cycles of transistor T and lasts about 0.25 seconds. The switching frequency of the transistor T is 20 kHz or more.

Since both terminals of the first electrode filament E1 are short-circuited to each other, that is, electrically connected to each other, this electrode filament E1 is connected to the low-pressure discharge lamp L
Is not preheated before firing.

After the ignition of the lamp L, this lamp L
Only a clearly low operating voltage of 10 volts is applied.
Since the flyback converter supplies power to the lamp L only during the cutoff phase of the transistor T, it is assumed that the lamp L is lit by a unipolar DC pulse. That is, the diode D1 has a certain cut-off delay that allows a short-time current flow in the cut-off direction, so that a high-frequency alternating current flows through the lamp L. A sufficiently high heating current through the second electrode filament E2 of the lamp L flows only during the interruption phase of the transistor T and likewise before the ignition of the lamp L. Capacitor C4 is used to smooth the ignition voltage and allows good ignition of the fluorescent lamp.

The base drive of the switching transistor T includes, in addition to the feedback winding N3 of the transformer, an adjustable resistor R2 connected in parallel with a capacitor C3, and a low-pass filter composed of a resistor R1 and a capacitor C2. .
This low pass filter filters out high frequency components from the base input signal of transistor T. Base series resistance R2
The switching frequency of the transistor can be adjusted to a target value, if properly designed by the capacitor C3 connected in parallel with the capacitor C3. Table 1 shows appropriate design data for the components used in the first embodiment.

FIG. 2 schematically shows a circuit diagram of a second embodiment of the present invention. This circuit device is likewise used for lighting a hand lamp with a small U-shaped fluorescent lamp. This circuit device also operates based on the principle of a single-ended flyback converter, and includes a transistor T ', one primary winding N4, two secondary windings N5, N6, and a ferrite core as main components. Transformer TR '. A battery or accumulator, for example, two minyon batteries supplying a supply voltage of about 2.5 V, is used as power supply. A relatively large-capacity electrolytic capacitor C7 is connected in parallel with the power supply. This input capacitor C7 is charged to the battery voltage and prevents the internal impedance, which increases with discharge of the battery, from adversely affecting the lamp lighting, i.e., the lamp brightness does not drop too much with increasing discharge of battery.

The capacitor C7 or the positive pole of the power supply is, on the one hand, at the beginning of the winding of the primary winding N4 of the transformer TR ', on the other hand, at the winding end of the first secondary winding N6, and at the first end of the capacitor C10. Terminal. The second terminal of the capacitor C10 is connected to both short-circuited terminals of the first electrode filament E1 'of the low-pressure discharge lamp L'. This first electrode filament E1 'is further connected to the cathode of the first diode D3.
The anode of this diode D3 is connected on the one hand to the winding end of the second secondary winding N5 and, on the other hand, to the auxiliary ignition capacitor C1.
2 first terminals. A second terminal of the starting auxiliary capacitor C12 is connected to the starting auxiliary electrode Z 'of the low-pressure discharge lamp L'. This ignition auxiliary electrode Z 'is provided outside the glass bulb or is a reflector made of a conductive material or provided with a conductive coating and partially surrounding the lamp.

The winding terminal of the primary winding N4 is led to the collector terminal of the switching transistor T ', while the emitter terminal of the transistor T' is connected to the input capacitor C7 or the negative pole of the power supply. Transistor T '
Is connected to the winding start end of the first secondary winding N6 of the transformer via low-pass filters R3 and C8 and an adjustable resistor R4. A capacitor C9 is connected in parallel with the adjustable resistor R4. The low-pass filter capacitor C8 is located in parallel between the base and the emitter of the transistor T '. A capacitor C for reducing the occurrence of power loss is connected in parallel between the collector and the emitter of the transistor T '.
11 are arranged.

Further, the winding end of the primary winding N4 is connected to the winding start of the second secondary winding N5. The beginning of the first secondary winding N6 is connected to the cathode of the second diode D4. The anode of this second diode D4 is the second electrode filament E2 of the low-pressure discharge lamp L '.
'Is connected to the first terminal. The second terminal of the electrode filament E2 'is connected to the first terminal of the capacitor C10, the winding start of the primary winding N4, and the winding end of the first secondary winding N6. The symbol S in FIG. 2 represents a switch for turning on and off the circuit device.

This circuit device also operates based on the functional principle of a single-ended flyback converter.
During the conducting phase of the transistor T ', the transformer TR' stores energy on the primary side and releases this energy to the lamp L 'via the secondary winding N5 during the cut-off phase. The switching transistor T 'is controlled by the first secondary winding N6 fed back to the primary winding N4.

When the switch S is closed, a current flows through the feedback winding N6 of the transformer TR 'to turn on the transistor T', which current flows through the primary winding N4 and the conducting collector-emitter of the transistor T '. Increase the current passing between them. When the current flowing through the primary winding N4 reaches a maximum value, a reverse polarity voltage called a flyback voltage is induced in the feedback winding N6, and this voltage is applied to the transistor T4.
´ is shut off. After the disappearance of the inductive event, the transistor T 'is turned on again by the feedback between the primary winding N4 and the feedback winding N6. This starts a new switching cycle.

When the transistor T 'is turned off, an induced voltage is generated in the second secondary winding N5, which also generates the necessary ignition or ignition voltage for the lamp L'. Diode D3 and still cold lamp electrode filament E2 '
Low resistance prevents immediate ignition of lamp L '. First, the heating current supplied from the feedback winding N6 flows through the diode D4 and the second electrode filament E2 'of the lamp L'. During the electrode preheating phase, the second electrode filament E2 'in the cutoff phase of the switching transistor T'
That is, a voltage obtained by subtracting only the voltage drop of the diode D4 from the flyback voltage of the feedback winding N6 is applied to both terminals of the electrode filament E2 '. As the heating of the electrode filament E2 'increases, its resistance increases, so that the voltage induced in the secondary winding N5 likewise increases,
An ignition voltage of about 700 volts is obtained between the lamp electrodes E1 'and E2', and the lamp L 'is ignited, thereby electrically conducting the discharge section. The electrode heating phase is transistor T '
For a number of switching cycles and lasts about 0.25 seconds. The switching frequency of the transistor T 'is 20 kHz or more.

Since the two terminals of the first electrode filament E1 'are short-circuited to each other, that is, electrically connected to each other, this electrode filament E1' is not preheated before the ignition of the low-pressure discharge lamp L '. .

After the ignition of the lamp L ', only a distinctly lower operating voltage of about 110 volts is applied to this lamp L'. Since the flyback converter supplies power to the lamp L 'only during the cut-off phase of the transistor T', it is assumed that the lamp L 'is lit by a unipolar DC pulse. The diode D3 thus has a certain cut-off delay allowing short-time current flow also in the cut-off direction, and therefore the lamp L3
And a high-frequency alternating current flows through it. A sufficiently high heating current through the second electrode filament E2 'of the lamp L' flows only during the blocking phase of the transistor T 'and likewise before the ignition of the lamp. Capacitor C10 is used to smooth the ignition voltage and allows a good ignition of the fluorescent lamp.

The base drive of the switching transistor T 'includes an adjustable resistor R4 connected in parallel with a capacitor C9 in addition to the feedback winding N6 of the transformer, and a low-pass filter composed of a resistor R3 and a capacitor C8. I have. This low pass filter filters out high frequency components from the base input signal of transistor T '. With the base series resistor R4 and the capacitor C9 connected in parallel with it, the switching frequency of the transistor can be adjusted to a target value if properly designed.

The function of the second embodiment is completely similar to that of the first embodiment. The main difference is that in the second embodiment, the heating voltage for preheating the second electrode filament E2 'of the low-pressure discharge lamp L' is mainly determined only by the flyback voltage in the feedback winding, It is not determined by the sum of the partial voltages in the primary winding and the feedback winding as in the case of the embodiment. For this reason, in the second embodiment, the first secondary winding of the transformer TR ', that is, the feedback winding N6, has a clearly larger number of turns than the primary winding N4. Suitable design data for the components used in the second embodiment are shown in Table 2.

FIG. 3 is a schematic circuit diagram of a third embodiment of the present invention. This circuit device is likewise used for lighting a hand lamp with a small U-shaped fluorescent lamp. This circuit device also operates based on the principle of a single-ended flyback converter, and includes a transistor T ″, one primary winding N7, and two secondary windings N as main components.
8, N9 and a transformer TR '' having a ferrite core. A battery or accumulator, for example, two minyon batteries supplying a supply voltage of about 2.5 V, is used as power supply. A relatively large-capacity electrolytic capacitor C13 is connected in parallel with the power supply. This input capacitor C1
3 is charged to the battery voltage and prevents the internal impedance, which increases with discharge of the battery, from adversely affecting the lamp operation, i.e. the lamp brightness does not fall too much with increasing discharge of the battery.

The capacitor C13 or the positive pole of the power supply is, on the one hand, at the beginning of the winding of the primary winding N7 of the transformer TR '', on the other hand, at the winding end of the first secondary winding N9 and at the end of the winding of the capacitor C16. 1 terminal. The second terminal of this capacitor C16 is connected to both short-circuited terminals of the first electrode filament E3 of the low-pressure discharge lamp L ''. This first electrode filament E3 is further connected to the cathode of a first diode D5. The anode of this diode D5 is connected on the one hand to the winding end of the second secondary winding N8 and on the other hand to the first terminal of a starting auxiliary capacitor C18. The second terminal of the starting auxiliary capacitor C18 is connected to the starting auxiliary electrode Z '' of the low-pressure discharge lamp L ''. This ignition auxiliary electrode Z '' is provided outside the glass bulb or is a reflector made of a conductive material or provided with a conductive coating and partially surrounding the lamp.

The terminal end of the primary winding N7 is led to the collector terminal of the switching transistor T '', while the emitter terminal of the transistor T '' is connected to the input capacitor C13 or the negative pole of the power supply. The base terminals of the transistor T ″ are low-pass filters R5 and C14.
And the first secondary winding N of the transformer via an adjustable resistor R6.
Nine windings. A capacitor C15 is connected in parallel with the adjustable resistor R6. The low-pass filter capacitor C14 is located in parallel between the base and the emitter of the transistor T ''. A capacitor C17 for reducing the occurrence of power loss is arranged in parallel between the collector and the emitter of the transistor T ''.

Further, the winding end of the primary winding N7 is connected to the winding start of the second secondary winding N8. The winding start end of the first secondary winding N9 is connected to the anode of the second diode D6. The cathode of this second diode D6 is the second electrode filament E4 of the low-pressure discharge lamp L ''.
Are connected to the first terminal of The second terminal of the electrode filament E4 is connected to the negative electrode of the power supply or the negative terminal of the electrolytic capacitor C13. Reference symbol S in FIG. 3 represents a switch for turning on and off the circuit device.

This circuit device also operates based on the functional principle of a single-ended flyback converter.
During the conducting phase of the transistor T '', the transformer TR '' stores energy on the primary side and releases this energy to the lamp L '' via the secondary winding N8 during the cut-off phase. The switching transistor T '' is controlled by the first secondary winding N9 fed back to the primary winding N7 and the components R6, C15.

When the switch S is closed, a current flows through the feedback winding N9 of the transformer TR '' to turn on the transistor T '', and this current turns on the primary winding N7 and the transistor T ''. Increase the current passing between the collector and the emitter. When the current flow through the primary winding N7 reaches a maximum value, a reverse polarity voltage is induced in the feedback winding N9, which shuts off the transistor T ''. After the disappearance of the inductive event, the transistor T '' is turned on again by the feedback between the primary winding N7 and the feedback winding N9. This starts a new switching cycle.

When the transistor T '' is switched off, an induced voltage is generated in the second secondary winding N8 which also generates the necessary ignition or operating voltage for the lamp L ''. Diode D5 and still cold lamp electrode filament E4
Low resistance prevents the immediate ignition of the lamp L ''.
First, the heating current supplied from the induced voltage in the first secondary winding and the battery voltage flows through the diode D6 and the second electrode filament E4 during the conducting phase of the transistor T ″, and this heating current is Before the low-pressure discharge lamp L ″ is ignited, the lamp electrode E4 is heated. During the conducting phase of the switching transistor T ″, the induced voltage of the first secondary winding N9 is polarized such that this induced voltage and the battery voltage are added to serve as a heating voltage for the electrode filament E4. The electrode heating phase extends over a number of switching cycles of transistor T ″ and lasts about 0.25 seconds. The switching frequency of the transistor T ″ is 2
0 kHz or more. Thereafter, the low-pressure discharge lamp L '' is ignited, and a gas discharge is formed between the two electrode filaments E3 and E4.

Since both terminals of the first electrode filament E3 are short-circuited to each other, that is, electrically connected to each other, this electrode filament E3 is connected to the low-pressure discharge lamp L
It is not preheated before the ignition of ''''.

After the ignition of the lamp L '', this lamp L ''
Only a very low ignition voltage of about 110 volts is applied. Flyback converter is transistor T ''
Is supplied to the lamp L '' only during the cutoff phase of the lamp L '', it is assumed that the lamp L '' is lit by a unipolar DC pulse. The diode D5 thus has a certain cut-off delay allowing short-time current flow also in the cut-off direction, so that a high-frequency alternating current flows through the lamp L ''. Capacitor C16 is used to smooth the ignition voltage and allows good ignition of the fluorescent lamp.

The base driving portion of the switching transistor T ″ is connected to a capacitor C15 in addition to the feedback winding N9 of the transformer.
Are connected in parallel, and a low-pass filter composed of a resistor R5 and a capacitor C14. This low-pass filter filters out high-frequency components from the base input signal of the transistor T ″. Base series resistor R6 and capacitor C1 connected in parallel thereto
5, the switching frequency of the transistor can be adjusted to a target value when properly designed.

Table 3 shows appropriate design data of the parts used in the third embodiment.

The invention is not limited to the embodiments described in detail above. For example, it is also possible to preheat both electrode filaments of the low-pressure discharge lamp before the lamp is ignited by stopping the short circuit of both terminals of the electrode filament E1, E1 'or E3. Furthermore, the variable resistance R
A dimming potentiometer that enables dimming of the low-pressure discharge lamp or energy-saving lighting can also be connected in series with 2 or R4. Energy-saving lighting means that the lamp is lit with less power than the rated power.

[0047]

Table 1 Design data of the circuit device according to the first embodiment Ferrite / transformer EF16 N1, N3 25 turns N2 420 turns R1 47Ω R2 1KΩ C1 100μF C2, C5 10nF C3 22nF C4 100pF T D882-Y D1, D2 1N4937

[0048]

Table 2 Design data of the circuit device according to the second embodiment Ferrite / transformer EF16 N4 25 turns N6 50 turns N5 420 turns R3 47Ω R4 1KΩ C7 100μF C8, C11 10nF C9 22nF C10 100pF T ′ D882-Y D3, D4 1N4937

[0049]

Table 3 Design data of the circuit device according to the third embodiment Ferrite / transformer EF16 N7, N925 turn N8 420 turn R5 47Ω R6 1KΩ C13 100μF C14, C17 10nF C15 22nF C16 100pF T '' D882-Y D5, D6 1N4937

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a circuit device according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the circuit device according to the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the circuit device according to the present invention.

[Explanation of symbols]

 T, T ', T' 'Switching transistor TR, TR', TR '' Transformer L, L ', L' 'Low-pressure discharge lamp C1, C7, C13 Electrolytic capacitors R2, R4, R6 Adjustable resistors N1, N4, N7 Primary winding N3, N6, N9 First secondary winding N2, N5, N8 Second secondary winding D1, D2, D3, D4, D5, D6 Diode E1, E1 ', E3 First electrode Filaments E2, E2 ', E4 Second electrode filaments Z, Z', Z '' Firing auxiliary electrodes C2, C3, C4, C5 Capacitors C8, C9, C10, C11 Capacitors C14, C15, C16, C17 Capacitor C6, C12, C18 Ignition auxiliary capacitor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Walter Hirschyumann Germany 81827 Miyunchen Huaustschlasse 70

Claims (5)

[Claims] 1. A transistor (T) and a transformer (TR)
, The primary winding (N1) of the transformer (TR) is connected in series with the switching section of the transistor (T) and has first and second terminals, (TR) has a first secondary winding (N3) and a second secondary winding (N2), each having first and second terminals, and a first secondary winding (N3). N3) is used to drive the control electrode of the transistor (T), the first terminal of the primary winding (N1) being the first terminal
In the circuit device for lighting a low-pressure discharge lamp with a low-voltage power supply connected to a second terminal of a secondary winding (N3), the second terminal of the primary winding (N1) is connected to the low-pressure discharge lamp (L). ) Via a second lamp electrode (E2) and a second diode (D2) capable of providing a preheating voltage of
A circuit device for lighting a low-voltage discharge lamp with a low-voltage power supply, which is connected to a first terminal of a secondary winding (N3). 2. A transistor (T ′) and a transformer (TR)
') Is formed as a single-ended flyback converter with a primary winding (N4) of the transformer (TR') connected in series to the switching section of the transistor (T ') and having first and second terminals Holding, transformer (TR ')
Is the first secondary winding (N6) and the second secondary winding (N5)
Which have first and second terminals, respectively.
The first secondary winding (N6) is a circuit device for lighting a low-pressure discharge lamp with a low-voltage power supply used to drive a control electrode of a transistor (T '). The first terminal of N6) is a diode (D4) and a preheatable lamp electrode (E2 ') of the low-pressure discharge lamp (L').
Circuit device for lighting a low-pressure discharge lamp with a low-voltage power supply, wherein the circuit device is connected to a second terminal of a first secondary winding (N6) through a second terminal. 3. A transistor (T '') and a transformer (T '').
R '') as a single-ended flyback converter with a primary winding (N '') of the transformer (TR '').
7) is connected in series with the switching section of the transistor (T '') and has first and second terminals, and the transformer (TR '') has a first secondary winding (N9) and a second It has secondary windings (N8), each having first and second terminals, the first secondary winding (N9) being used to drive the control electrode of the transistor (T ''). The second terminal of the first secondary winding (N9) is a low-voltage power supply connected to the first pole of the low-voltage power supply. First of the next winding (N9)
Is connected via a diode and the preheatable lamp electrode (E4) of the low-pressure discharge lamp (L '') to the second terminal of the low-voltage power supply.
Circuit device for lighting a low-pressure discharge lamp with a low-voltage power supply, wherein the circuit device is connected to the negative electrode. 4. The circuit device comprises a low-pressure discharge lamp (L; L ';
The circuit device according to claim 1, further comprising a terminal for the auxiliary ignition electrode (Z; Z ′; Z ″) of L ″). 5. A second secondary winding (N2; N5; N8) is connected to a first terminal of a capacitor (C6; C12; C18), the second terminal of which is connected to a low-pressure discharge lamp (L). L ′; L ″) firing auxiliary electrode (Z; Z ′; Z ′)
The circuit device according to claim 4, wherein the circuit device is connected to a terminal for (1).