Robert Boschgmbh

Robert Kern

Karl-Heinrich Preis

Hartmut Seiler

Lothar Borho

Thomas Mohr

Klaus Eckert

Gerhard Decker

Claus Schmiederer

Bernd Mueller

Ingo Gorille

Peter Braun

Wolfgang Schwenk

Joerg Sutter

Michael Soellner

Johann Freundorfer

Thomas Wizemann

Oliver Heyna

Wolfgang Pfaff

Ernst Damerau

Wolfgang Schuetze

Tobias Kiefer

Ulrich Exner

R&uuml;diger Laubenstein

A device for monitoring signal levels of signals that are generated, for the purpose of detecting a magnetic field, by a plurality of Hall sensors includes a first, second, and third input and a diagnostic device. The first input is configured to receive a first signal from a first Hall sensor. A first electrical resistor is connected between the first input and a central point. The second input is configured to receive a second signal from a second Hall sensor. A second electrical resistor is connected between the second input and the central point. The third input is configured to receive a third signal from a third Hall sensor. A third electrical resistor is connected between the third input and the central point. The diagnostic device is connected to the central point and is configured to determine a position of the detected magnetic field using an average value.

Device and method for monitoring signal levels

A method for detecting the resonance frequency of an electrical oscillation circuit, in particular that of a starter oscillation circuit for high-pressure gas discharge lamps, is described in which the oscillation circuit is excited with various frequencies. The frequency search is undertaken in a search run with individual search attempts. A specific, fixed frequency is used for the sampling tests. Each fixed frequency is selected and used according to a specific search pattern. In the search pattern, the first sampling test is carried out with the mean frequency, which is the mean between the minimum and maximum possible resonance frequencies. In each of the subsequent sampling tests, the test frequency is modified in steps. The resonance frequency found in a search run can be stored as a learning frequency for use as a starting frequency for subsequent search runs and updated as necessary.

Method for determining the resonance frequency of an electric resonant circuit

A circuit for detecting an impermissibly high current in an output stage contains two transistors arranged in a bridge branch of a bridge circuit. A comparator compares the voltage obtained at the connection point of the two transistors with the voltage obtained at the center tap of a voltage divider connected to the power supply terminals. A switching transistor changes the voltage divider ratio of the voltage divider as a function of the switching signal of one of the transistors.

Circuit for detecting and inadmissibly high current in an output stage

A gaseous-discharge lamp, in particular for motor-vehicle headlamps, includes a burner vessel made of glass or the like that contains a gas. Into this burner vessel extend two main electrodes via two gas-tight electrode bushings. Between the end regions of the main electrodes arranged in the burner vessel, an arc gap is formed, along which an electric arc develops during operation. To achieve a smallest possible ignition voltage, an arrangement is provided for producing a creepage spark gap along the inner vessel wall and/or a spark gap that is shorter than the arc gap, serving as an ignition gap that is spatially separated from the arc gap.

Gas discharge lamp, in particular for motor-vehicle headlights

A polarity reversal protective circuit for an electronic power output stage that can be driven via a drive circuit is described. In the case of an incorrect polarization of a supply voltage, power FETs are used in at least one supply terminal to interrupt a connection of the wrongly applied supply voltage to the drive circuit and the power output stage. A definite polarity reversal protection is obtained using a circuit that is improved with respect to cost and space requirement. A single N-channel power FET is looped, with its source-drain path, into the positive supply terminal of the supply voltage. The source terminal of the N-channel power FET is connected with the positive supply terminal. The gate terminal of the N-channel power FET is connected to a collector of a PNP transistor, which is additionally connected to an output of the drive circuit via a current-limiting resistor. An emitter of the PNP transistor is connected&mdash;via a diode that is conductive when the supply voltage is wrongly applied&mdash;to the positive supply terminal. The base of the PNP transistor is connected&mdash;via a base resistor&mdash;to a negative (ground) supply terminal of the supply voltage.

Polarity reversal protection circuit for a final electronic power stage

A DC-DC converter having a transformer, a reactance coil and a controllable switch for turning a DC supply voltage on and off. The contact gap of a switching transistor is set at a reference potential at a connecting tap between a primary winding and a secondary winding of the reactance coil, which is connected like a transformer with a certain transformation ratio. The anode-cathode segment of a diode and an output capacitor are set at reference potentials in series with the secondary winding of the reactance coil, with the output voltage for a load being applied across the output capacitor. The DC supply voltage is supplied to the primary winding of the reactance coil over an inductance arrangement, and a capacitance arrangement is arranged in parallel with the contact gap of the switching transistor so that a series resonant circuit, which is operative in the turn-on and turn-off phases of the switching transistor, is provided by the inductance arrangement and the capacitance arrangement.

D.C.-d.c. converter with a transformer and a reactance coil

A control circuit for a direct-current motor driven in a clocked manner, includes an electrolytic capacitor connected in parallel and free-wheeling diode. Spurious radiation is reduced, in that a choke is connected between the positive motor supply voltage and the plus terminal of the electrolytic capacitor, and that the free-wheeling diode is disposed with its cathode between the choke and the electrolytic capacitor, and with its anode on the negative side of the d.c. motor.

Control circuit for a dc motor

An arrangement for protecting a control device for gas discharge lamps from overtemperature contains a control device and a DC/DC converter. Regulation of the power conveyed to the gas discharge lamp is performed. The output value of the power controller (to be considered the manipulated variable) and the input value of the power controller (to be considered the setpoint) are ascertained by way of the control device. The ratio of these two values (manipulated variable to setpoint) is determined. The value determined for that ratio can be used to limit the output power of the control device. The control device may contains a microcontroller, and the controller is provided as a program in the microcontroller and is implemented as software in order to limit the output power of the control device.

Overheating protection device for a control device in gas discharge lamps

Proposed is a gaseous-discharge lamp, in particular for motor-vehicle headlamps, comprising a burner vessel of glass or the like having at least two electrodes, the burner vessel being provided with a lamp base that includes the electrical terminals and that is insertable into a lamp base socket. Arranged in the lamp base is an electronic ballast unit that supplies the lamp with the necessary ignition and maintaining voltage. By accomodating the balast unit in the lamp base, one can achieve a small-volume gaseous-discharge lamp having short high-voltage leads i an integrated type of construction, making it possible to keep the ignition voltage to a minimum.

Gas discharge lamp, in particular for a motor-vehicle headlight

A device for operating a gas discharge lamp (,), with the device including an energy supply circuit which provides an alternating-current voltage (U,) or an alternating current (I,) having a predetermined period (T,) during operation at normal rating in order to feed the gas discharge lamp (,) with a predetermined electrical power. When the average lamp power is reduced with respect to operation at normal rating, an extension of the period (T,&plus;T,, T,&plus;T,) is provided. The amount of the extension of the period (T,&plus;T,, T,&plus;T,) is a function of the amount of the reduction in power. The device of the invention for operating the gas discharge lamp (,) extensively prevents an extinguishing of the light arc located in the gas discharge lamp (,) during the pole-reversal process, and therefore assures re-ignition following the pole-reversal process, even during operation with reduced power. A preferred use of the device of the invention is in a gas discharge lamp installed in a motor vehicle.

Device for operating a gas discharge lamp with reduced average lamp power

A device for operating a gas discharge lamp (,) is proposed, having a power supply circuit which makes available an alternating voltage (U,) or an alternating current (I,) of a predetermined period duration (T,) for the supply of the gas discharge lamp (,) with predetermined electrical power. During an intended reduction of the mean lamp rating compared to the operation at normal rating, an increase of the instantaneous power is provided within a half period duration (T,/2) prior to the pole change of the alternating voltage (U,) or alternating current (I,). Preferably, the duration of the increase of the instantaneous power is a function of the period duration (T,). The device according to the invention for operating the gas discharge lamp (,) largely prevents the arc comprised in the gas discharge lamp (,) from going out during the pole-changing process and therefore ensures reignition following the pole-changing process. A preferred application of the device according to the invention is a gas discharge lamp (,) which is installed in a motor vehicle.

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Buehlertal, Germany

Robert Kern