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Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Osram Gesellschaft MIT Beschraenkter Haftung

Osram Gmbh

Osram Ag

Peter Krummel

Andreas Mitze

Max Kerscher

Manfred Klamt

Armin Kroning

Various embodiments may relate to a circuit arrangement and a method for operating and dimming at least one LED. In this case, the LEDs are supplied from a bridge arrangement, wherein, in order to dim the at least one LED, the frequency of the control signals is increased with increasing dimming until a predefinable dimming threshold value. In order to adjust dimming values which are below the predefinable dimming threshold value, the output signal of the bridge arrangement is short-circuited by means of a short-circuit device during predefinable periods.

Circuit arrangement and method for operating and dimming at least one LED

Various embodiments relate to a circuit arrangement for operating at least one discharge lamp. In order to prevent intrinsic flicker at low dimming settings and low temperatures, according to various embodiments, a direct current which is fed into the discharge lamp so as to avoid striated discharges at relatively high dimming settings is reduced or entirely eliminated.

Circuit arrangement and method for operating at least one discharge lamp

A method for operating a lamp, wherein in the preheating phase a first value of the voltage drop correlated with the reciprocal of the electrical resistance of a coil of the lamp is determined across a resistor at a first instant, and a second value of the voltage drop is determined at a second instant, may include: a) determining the difference between a first and the second value; b) b1) if the difference is greater than a first threshold value: carrying out an algorithm for lamp-type recognition; b2) if the difference is not greater than the first threshold value: c1) if the difference is greater than a second threshold value: d1) if the second value is greater than a third threshold value: determining a coil short circuit; d2) if the second value is not greater than the third threshold value: operating the lamp with the current set of operating parameters.

Method and circuit arrangement for operating at least one discharge lamp

A circuit arrangement for operating at least one discharge lamp may include: a first and a second input terminal for connecting a supply voltage; an inverter, which includes at least one first switch and one second switch, which are coupled in series between the first and the second input terminal and between which a bridge center point is defined; a drive circuit for at least the first switch and the second switch with an input for receiving a control signal; an apparatus for generating an auxiliary voltage. The apparatus may include: a first capacitor; a terminal for the provision of the auxiliary voltage, which terminal is coupled to a reference potential via the first capacitor; a two-state controller with a first input to which the control signal in inverted form is coupled, a second input, which is coupled to the terminal for the provision of the auxiliary voltage, and an output; a switch&#x2014;with a control electrode, a working electrode and a reference electrode, the control electrode being coupled to the output of the two-state controller, the working electrode being coupled to the terminal for the provision of the auxiliary voltage; and a nonreactive resistor; wherein the apparatus for generating the auxiliary voltage furthermore includes a transformer with a primary winding and a secondary winding, the transformer being coupled to the first and the second input terminal, the terminal for the provision of the auxiliary voltage and the switch-in such a way that a current through the switch results in a current through the primary winding, in a current through the secondary winding and therefore in charging of the first capacitor.

Circuit configuration for operating at least one discharge lamp and method for generating an auxiliary voltage

A method for operating at least one low-pressure discharge lamp having heatable lamp electrodes, in which, during the preheating phase of the lamp electrodes, the type of lamp is identified. In this case, the temperature dependence of the electrical resistance of the lamp electrodes is exploited.

Method for operating at least one low-pressure discharge lamp

The invention relates to a microcontroller (MC) having at least one device (G) for generating pulse-width modulated or frequency modulated control signals for a switched-mode power supply. The device (G) has a further device (SQ , SS ) for the alternate charging and discharging an electric charge store (C ) that can be connected to the microcontroller (MC), control means for this device (SQ , SS ) for controlling the charging and discharging operations, and an evalutor for evaluating the time periods which are needed for the individual charging and discharging operations to generate pulse-width modulated or frequency modulated control signals. The microcontroller (MC) generates finely graduated, frequency modulated or pulse-width modulated control signals which are independent of the operating cycle frequency of the microcontroller (MC).

Microcontroller, switched-mode power supply, ballast for operating at least one electric lamp, and method of operating at least one electric lamp

An integrated control and regulating circuit (IC) controls, via a half-bridge circuit (V,V,), a load circuit (,) having the at least one fluorescent lamp (FL) by means of a drive circuit (CCO, SEL, HSD, LSD) regulated in a high-frequency manner. In the control and regulating circuit, each time the lamp is started and/or when there is a disturbance, a timer (PST, IT, CT) is started, which thus defines a sequence predetermined periods of time (&Dgr;pt, &Dgr;it, &Dgr;st, &Dgr;ot), inter alia preheating period (&Dgr;pt) and ignition period (&Dgr;it). In a monitoring circuit (MON), the pulsed load current of the load circuit is cyclically monitored in comparison with reference levels (Mp, Mi, Mdo and Mo) which are respectively predetermined for the periods of time, in order to detect a normal state or a disturbance in the load circuit, to control the current regulation of the drive circuit (CCO, ISC, SEL, HSD, LSD) in the normal state, or to trigger an automatic disconnection of the electronic ballast in the event of a disturbance. During the ignition period (&Dgr;it), a current signal which is derived from the load current and is fed to the monitoring circuit (MON) has superposed on it an internally generated DC signal (DC) having a defined level. The value thereof is dimensioned in accordance with the types and/or circuits of the fluorescent lamp(s) which are used in the load circuit, with the result that the signal that is superposed in this way is adapted to the predetermined, fixed reference levels (e.g. Mp, Mi) of the monitoring circuit (MON) independently of the lamp selection in the load circuit.

Method for operating at least one fluorescent lamp, and electronic ballast therefor

A circuit arrangement used with electronic ballast equipment has an inverter which supplies a high-frequency half-bridge voltage to at least one load circuit having a lamp throttle, a fluorescent lamp, an ignition capacitor, and a half-bridge capacitor. In order to pre-heat the coils of the fluorescent lamp in a short period of time, a switchable voltage source is activated. This voltage source is connected to the output of the inverter. The outputs of the voltage source are constructed as a pair, to which the electrodes and the fluorescent lamp are connected in parallel. This voltage source includes a transformer having a primary winding coupled to the inverter and is switched between non-conducting and conducting (energized) states by a switching stage. The secondary windings of the transformer are connected in parallel to the electrodes of the fluorescent lamp.

Circuit arrangement for electrode pre-heating of a fluorescent lamp

Method for operating at least one fluorescent lamp with an electronic

Electronic ballasts are essentially composed of a series connection of a harmonic filter that has its input side connected to the AC line, a rectifier and an inverter to which is connected at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a fluorescent tube and a capacitor. When a high electric tolerance is required of such a ballast in view of a desired increase in the power factor, standard circuit designs required a relatively expensive storage capacitor that smooths the AC rectified line voltage. In order to be able to use a storage capacitor that has a lower electric tolerance in comparison to the required voltage tolerance of the ballast, a storage capacitor is incorporated into one of the two capacitor branches of the inverter which is composed of a switch bridge arrangement having two switch branches and two capacitor branches, this storage capacitor being connected in series with the actual load.

Electronic ballast for fluoroscent lamps

A shut-off device is provided for an inverter which feeds at least one discharge lamp, the shut-off device operable to shut-off the inverter in limiting cases and remaining in this condition until a lamp replacement. The shut-off device flips into its normal condition when a holding current in a monitoring circuit falls below a flyback limit value. In order to keep the losses as low as possible, the monitoring circuit is dimensioned high-resistant and a separate holding circuit is provided, the separate holding circuit having a controlled dependency on the low control current in the monitoring circuit. In the disconnect case, the control current also suffices to hold the shut-off device in the disconnect condition when an electrode is broken.

Arrangement for shutting off an inverter

In an inverter controlled with a firing unit connected to switches and defining an operating frequency, a resonant frequency of a series oscillating circuit of the inverter connected to one of the switches is placed below this operating frequency. Given this operating situation, a short of the d.c. voltage source is impossible. Given, for example, unfavorable component tolerances, however, the operating frequency can be moved close to the resonant frequency and cause impermissibly high voltages at the components. Such a voltage rise is limited according to the invention by means of a voltage-dependent resistor. It preferably lies in series with a capacitor and takes care of a voltage-dependent shift of the resonant frequency.

Inverter with a load circuit containing a series oscillating circuit and

An inverter with a dc-source has a charging condenser connected through a charging diode and a charging inductor to the dc-supply. A charging switch is periodically closed by a control component with a variable keying ratio to connect the charging inductor to the dc-supply. The inverter includes an AC voltage converter with two alternatingly controlled switches supplied with power by the charging condenser, hereinbelow identified as the primary switch and the secondary switch, which are in a series circuit in parallel with the charging condenser. In this arrangement, the control component for the charging switch of the charging regulator is synchronized with a square wave voltage at one of the switches of the alternating voltage converter. The charging switch operates at the same switching frequency as the alternating voltage converter. When the square-wave voltage at a switch of the alternating voltage converter terminates during a non-oscillating condition of the alternating voltage converter, then the charging switch of the charging regulator also remains open. At a disruption, there need, accordingly, only be deactivated the inverter.

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Traunreut, Germany

Peter Krummel