Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Patent-treuhand-gesellschaft

Frank Hansmann

Andreas Huber

Franz Bernitz

Josef Osterried

Eugen Statnic

Alwin Veser

To largely, or entirely inhibit glow discharges during the start-up or run-on phase (Ta) of a high-pressure discharge lamp, the lamp is operated in a second time period (T2) immediately after ignition (T1) with continuous direct current during which the electrode of the lamp which then functions as an anode has reached emission temperature; in a third time period (T3), the polarity of the direct current is reversed and the other electrode, which now will function as an anode, is heated to emission temperature; thereafter, alternating current energy is supplied to both electrodes, typically in frequencies between 90 and 150 Hz. A suitable second time period (T2) can be about 2 to 21/2 second, the third time period (T3) being shorter. The total warm-up time may extend to a minute or more; current being supplied during the second, third and subsequent periods is usually higher, for example by a factor of 1.5 of the normal or rated operating current.

Ignitional run circuit that immediately applies only a DC voltage after

To ensure ignition of a high-pressure discharge lamp, for example a metal vapor halogen high-pressure dicharge lamp which has an ignition circuit, and is operated by direct current from an inverter circuit controlled for pulse width modulation, current flow to the lamp is extended in time upon initial energization thereof so that an initial hot spot which forms on an electrode can remain hot to establish a stabilized arc. This extension of current flow can be obtained by an R/C circuit in parallel to the output or storage capacitor (C.sub.A) of the inverter circuit (FIG. 1) or by an NTC resistor (H) in series with the lamp, or by a resistor which is short-circuited by a relay contact as the lamp operates, or the like.

High-pressure discharge lamp with pulsed inverter operating circuit, and

A switched mode power supply (SNT) is coupled to a source of d-c energy (U.sub.Batt) and provides electrical energy to a lamp within widely varying limits. The switching conditions of the switched mode power supply are controlled by an operation control circuit (ADD) which has a current sensing resistor, serially connected to the lamp, to provide a lamp current signal, and a voltage divider (R2, R3) connected across the lamp to sense lamp voltage and provide a lamp voltage signal. The lamp current signal and the lamp voltage signal are added, compared in a comparator formed by an operational amplifier (IC2-A), with respect to a reference setting power level, and the output signal from the comparator is coupled back to the switched mode power supply to control the switching rate thereof, based on the instantaneous lamp current and lamp voltage. Excess voltage can be compensated by providing either an active semiconductor switching network (T1, T2, FIG. 3) or a passive semiconductor switch (ZD), which affects the added current-voltage signal applied to the comparator (IC2-A).

Operating circuit for a discharge lamp

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.

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Barsinghausen, Germany

Frank Hansmann