Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Osram Sylvania Inc.

Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft

Patent-truehand Gesellschaft M.b.h.

Eugen Statnic

Valery A Godyak

Felix Franck

Franz Bernitz

Alwin Veser

Bernhard Ertl

Hans-Jurgen Fahnrich

Ulrich Roll

Frank Hansmann

Erhard Rasch

Gunther Loehmann

Water Hirschmann

Wolfgang Tausch

A radio frequency (RF) power supply for an electrodeless lamp includes a pair of DC rails, an RF inverter having power input terminals connected between the rails, a first inductor arranged to inductively couple with an electrodeless lamp, first and second resonance capacitors that each connects a respective one of two input terminals of the first inductor to a same first rail of the pair of DC rails, and a second (ballasting) inductor connecting an output of the RF inverter to one of the two input terminals of the first inductor. Thus, the first inductor is connected in a symmetrical &#x3c0;-filter and supplied by two equal but phase-opposite voltages whose sum is the lamp voltage. The inductance of the ballasting inductor is significantly reduced so that the RF efficiency of the power supply is 96%.

Symmetrical RF power supply for inductively coupled electrodeless lamps

An electrical circuit arrangement for producing pulsed-voltage sequences for the operation of discharges which are impeded dielectrically comprises a series circuit formed from a tuned circuit inductance (TR,-A) and a controlled switch (T,), a pulse generator (OS) which drives the switch (T,), an electrical valve (D,) which is connected in parallel with the switch (T,), a tuned circuit capacitance (C,) which is likewise connected in parallel with the switch (T,), a means (TR,-B, a&Prime;, b&Prime;) for coupling a lamp (La,) to at least one electrode which is impeded dielectrically, and, optionally, a buffer and feedback capacitor (C,) which is connected in parallel with the series circuit formed by the tuned circuit inductance (TR,-A) and the switch (T,). The means for coupling a lamp comprises in particular two connections (a&Prime;, b&Prime;) and the secondary winding (TR,-B) of an autotransformer (TR,), which is connected between a first pole of the switch (T,) and the corresponding connection (a&Prime;), the primary winding (TR,-A) of the autotransformer (TR,) acting as the tuned circuit inductance. The second connection (b&prime;) is connected to the second pole of the switch (T,). In operation, the switch (T,) opens and closes alternately in time with the drive signal of the pulse generator (OS), as a result of which a sequence of voltage pulses, which are separated by pauses, is produced at the electrodes, which are impeded dielectrically, of a lamp (La,) which is connected to the connections (a&Prime;, b&Prime;).

Process for generating voltage pulse sequences and circuit assembly therefor

The invention relates to an operating circuit for an electrodeless low-prure gas discharge lamp designed for power between some watts and some kilowatts having a switching system which operates at high frequency in a freewheeling mode close to resonance.

Operating circuit for an electrodeless low-pressure discharge lamp

To substantially reduce harmonic distortion and improve the power factor of n operating circuit for a fluorescent lamp, a smoothing circuit (G) is interposed between the outputs from a power rectifier (GL) and an inverter (WR) supplying the fluorescent lamp (L) with high-frequency energy. The smoothing circuit includes a two electrolytic capacitor (C1, C2)--three diode (D1, D2, D3) network, which is so connected, and the diodes so polarized that, during charging of the capacitors, a series circuit is established with one (D2) of the three diodes in series with the two capacitors. For discharge of the capacitors to supply the inverter when the rectified voltage is lower than the capacitor voltage, the two capacitors (C1, C2), through the other two diodes (D1, D3), are connected in parallel to supply the inverter. To substantially reduce harmonic distortion to less than about 30% and improve the power factor of the circuit to above 0.95, a parallel resistor-capacitor (RC) circuit is connected between two junctions (V1, V2) serially with the series connected diode (D2). The resistor (R1), in combination with the capacitors, reduces, and time-delays, inrush current upon charging of the capacitors (C1, C2). The capacitor (C3) connected in parallel to the resistor (R1) permits backflow of high-frequency current from the inverter to the electrolytic capacitors (C1, C2), thus preventing transfer back to the network supply.

Minimum harmonic distortion operating circuit for at least one

To insure high power factor for the operating circuit of a low-pressure discharge lamp, especially of miniature fluorescent lamps, a high-frequency active rectifier bridge (D1-D4) is provided which interrupts charging of a smoothing capacitor (C2), which smoothing capacitor supplies an inverter circuit (WR) in the switching rhythm of the inverter. A storage choke or inductance (L1), a negative feedback capacitor (CG) and an auxiliary capacitor (CS) are coupled to the high-frequency rectifier bridge (D1-D4) which, together with the inductance insure an approximately sinusoidal current being taken from a power network, with a power factor of 0.98 or higher. Preferably, the circuit includes voltage dividers (R8, R9, R11; R15, R16, R17) which are coupled to a voltage sensitive trigger circuit (DI, TH) to turn OFF alternate switching of transistors (T1, T2) of the inverter (WR) in case excess supply voltage or operating voltages of the lamp are sensed.

High power factor, high-frequency operating circuit for a low-pressure

A control circuit for controlling a known active harmonic filter operating as a step-up converter in a power supply with sinusoidal network current input and a power factor of almost unity. The step-up converter comprises: a main rectifier, a storage inductance (L.sub.S), a cross-connected high-speed transistor (T.sub.Q), a diode (D1) and a power storage capacitor (C.sub.L). The high-speed transistor (T.sub.Q) is controlled by a first threshold switch (STc) whose input is controlled by a control capacitor (C12) coupled to receive a signal representative of instantaneous rectified d.c. output voltage (U.sub.E), instantaneous power output voltage (U.sub.o) and a signal representative of the charge state of the inductance. The inductance charge signal is obtained from a voltage jump (ringing voltage) between the inductance and the diode (D1) by sensing a flank of an oscillation voltage occurring at the diode by a RC circuit (R8, C10), which triggers a second threshold switch (STa) to control charge reversal and recharge of the capacitor (C12), thus determining the time instants of operation of the first threshold switch to control the cross-connected electronic switch (T.sub.Q) to conduction, and hence re-storing of electrical energy in the inductance.

Regulated rectifier d.c. power supply

To operate a fluorescent lamp having a lamp operating voltage of to about 0 V from a power supply having a nominal voltage level below lamp operating voltage, and without use of a voltage doubler circuit or a transformer to increase the power supply voltage, the power supply voltage is rectified, chopped, and then applied to the fluorescent lamp through a voltage increasing circuit which is formed as an LC resonance circuit. The inductive component can be formed by the current limiting choke, already present in a typical fluorescent lamp circuit, and the capacitative component by a small capacitor, for example of 6 nF value, connected to the choke to form a series resonance circuit.

Power network fluorescent lamp operating circuit

To provide for reliable ignition of low-pressure discharge lamps, particularly compact fluorescent lamps, operated at high frequency, for example in the order of about 45 kHz, an ignition circuit is connected in parallel to the lamp and serially with the electrodes (16, 17) thereof, which comprises a limiting capacitor (19) and the parallel circuit of a positive temperature coefficient (PTC) resistor (20) and a starting capacitor (18). The two capacitors (18, 19), together with an inductance (13, 14) in the operating circuit of the lamp, and a further capacity formed by a blocking capacitor (15), after preheating of the lamp electrodes by current flowing through the initially cold PTC resistor, will cause voltage rise across the resonance capacitors (18, 19) which will cause ignition of the lamp. The ratio of the limiting capacitor to the starting capacitor is in the order of 1:1 to 5:1, preferably about 2:1, resulting in gentle ignition in minimum time, for example about 1/2 second after energization of the lamp.

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Munich, Germany

Eugen Statnic