Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh

Patent-Truehand Gesellschaft M.b.h.

Ulrich Roll

Hans-Jurgen Fahnrich

Eugen Statnic

Ludwig Reiser

Roland Kastl

Werner Bernhard

To eliminate the necessity for a saturated or air gap inductance to provide feedback circuit for a self-exciting oscillator including two active electronic switches (T1, T2) , for example MOSFETs, an auxiliary winding (HW1, HW2, . . . HW11) is inductively coupled to the resonance inductance (L2) present in the circuit for the discharge lamp (LP) anyway; and a pulse shaping - phase shifting network (R3, C3; R4, C4 . . . ) , devoid of inherent resonance, coupling the auxiliary winding to the active switching elements. The pulse shaping - phase shifting network is formed of a one or multiple-stage RC low-pass circuit, connected serially between the auxiliary winding and the control input, for example the gate, of the active switching element. The RC network can be constructed with variable elements, for example including PTC resistors, a varistor or the like, and may include a current source, protective circuits to protect against voltage peaks including Zener diodes. The low-pass characteristics of the pulse shaping - phase shifting network permits switching of the active semiconductor switches after the maximum current flow.

Transformerless fluorescent lamp operating circuit, particularly for a

To provide enhanced starting voltages for fluorescent lamps operating, for xample, from 110 V power networks through a rectifier, and in which a high-frequency oscillatory circuit is used which includes a ring core transformer (TR1, TR2, TR3) operated under saturation conditions, and controlling switching transistors (T1, T2), which have emitter-resistors (R4, R5) connected thereto to stabilize the operation of the circuit and of the transistors, at least one diode (FIG. 4: D4, D5) is connected in parallel to at least one of the emitter resistors; for some circuits (FIGS. 2-4) a diode, or two diodes (D6, D7, D8, D9) can form the emitter-resistors or resistors.

Fluorescent lamp high frequency 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.

Discharge lamp starting circuit particularly for compact fluorescent

To provide for reliable starting of compact-type fluorescent lamps, or ot discharge lamps difficult to start, a voltage divider which is formed only by serially connected capacitors (C1, C2) is connected across the lamp (L), the junction point (5) of the voltage divider being connected to a charging circuit formed by a resistor (R1) and a capacitor (C3). The junction (4) between the charging resistor and capacitor (R1, C3) is connected through a diac (D) to the trigger or gate electrode (3) of a triac (T) connected across the lamp. Preferably, the capacity relationship of each one of the capacitors (C1, C2) of the voltage divider to the trigger capacitor (C3) is between about 1:1 and 1:5, desirably about 1:3. The time constant formed by the charge circuit (R1, C3), preferably, is between about 4 to 6 milliseconds, so that the charge time of the trigger capacitor (C3) is sufficiently long to provide multiple starting pulses to the triac (T) at peak values. A circuit to provide for polarity independence (FIG. 2: G, R2) can be connected between the diac junction (4) and the charge capacitor (C3).

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Munich, Germany

Ulrich Roll