Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Osram Gesellschaft MIT Beschraenkter Haftung

Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Osram Gmbh

Alwin Veser

Andreas Huber

Josef Osterried

Christian Breuer

Bernd Rudolph

Simon Lankes

Eugen Statnic

Martin Honsberg-Riedl

Bernhard Ertl

Wolfram Graser

Frank Hansmann

Burkhard Ulrich

A starting circuit arrangement for starting at least one discharge lamp by applying an electrical starting voltage pulse to the discharge lamp, the starting circuit arrangement has: at least one source circuit arrangement for providing an electrical primary voltage pulse, at least one starting circuit for providing the starting voltage pulse, and at least one inductive coupling element for inductively coupling-in the primary voltage pulse into the starting circuit for the purpose of generating the starting voltage pulse. The inductive coupling element has a transformation ratio for a voltage transformation which is selected from the range of from 1/25 to 1/400. A method for starting a discharge lamp by applying a starting voltage pulse using the starting circuit arrangement is also disclosed.

Ignition circuit for igniting a discharge lamp and method for igniting the discharge lamp

The present invention relates to a driver circuit for an HID lamp having a circuit arrangement for applying a radiofrequency signal for the purpose of starting the lamp and for applying a low-frequency signal for the purpose of operating the lamp after starting, the driver circuit being designed to drive the HID lamp, immediately after starting, using a radiofrequency signal for a period of time, the period of time being variable and depending on at least one operating parameter for the lamp which is set after starting. It also relates to a corresponding method for operating an HID lamp.

Driver circuit for an HID lamp and method for operating an HID lamp

Flickering phenomena in gas discharge lamps are undesired in projection technology, in particular. According to the invention, the problem is solved by setting a lamp operation which does not form a focal spot. A specific control structure which includes a cascade structure and feedforward control is proposed for implementing this operation.

Stabilizing the operation of gas discharged 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

An electrical circuit arrangement for the production of voltage pulse sequences, in particular for the operation of dielectrically impeded discharges, has a charging circuit, with a charging capacitor (C2), fed with an input voltage (U.sub.E), a discharge and pulse circuit with a fast controllable switch, in particular with an IGBT (T1), which is connected to a clocked drive circuit (A), and a pulse transformer (TR1) with a load (L) connected thereto, and a feedback circuit with a feedback rectifier, for example semiconductor diodes (D3-D4) and a feedback energy accumulation circuit, for example a buffer capacitor (C1) connected in parallel with the input of the charging circuit. During each phase in which the IGBT is on, the electrical energy stored in the charging capacitor (C2) is transferred via the pulse transformer (TR1) to the load (L). The energy reflected from the load (L) and the pulse transformer (TR1) passes through the feedback diodes (D3-D5), is fed to the feedback point (R) and is received by the buffer capacitor (C1). During the reflection phases, the potential of the secondary winding is thereby clamped to the potential of the input voltage (U.sub.E). Furthermore, the energy fed back is in this way used as a contribution for the charging phases of the charging capacitor (C2).

Circuit arrangement for the production of voltage pulse sequences, in

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 operate one or more serially connected low-pressure discharge lamps, tcally fluorescent lamps, a preheating circuit is provided to preheat the electrodes of the lamps (E1, E2, E3, E4), which changes from low-impedance to high-impedance state after the lamps have been preheated by controlling a semiconductor switch (Q3) in the heating circuit. In accordance with the invention, to eliminate reliance on the resistances of the lamp filaments themselves, which are subject to variation from lamp-to-lamp due to manufacturing tolerances, and later on, to changes due to aging of the lamp, and to provide for reliable switching of the semiconductor switch, a sensing impedance element (Z), which may be an ohmic resistor or a capacitor (Z', Z'), is serially connected to the switching path of the semiconductor switch (Q3) which, typically, is a field effect transistor (FET). The voltage drop across the series circuit formed by the impedance element (Z, Z', Z') and the semiconductor switch (Q3) is set by suitable dimensioning of the impedance element, to be sufficient to retain the main switching path of the semiconductor switch in low-impedance state when it carries full heater current, that is, is already in low-impedance state. To change over to high-impedance state, control signals to the semiconductor switch are removed, for example by shunting a resistor (R2) in a voltage divider, thus turning the semiconductor switch (Q3) OFF.

Growing community of inventors

Hallbergmoos, Germany

Alwin Veser