Minebea Company, Limited

Em Microelectronic-marin Sa

Mykhaylo Raykhman

Manfred Schlenk

Hans Hoffmann

Robert Weger

Josef Fisch

Yves Theoduloz

Fabien Maupas

Daniel N Luthi

Martin Feldtkeller

Michael Herfurth

The invention describes a control circuit for backlighting having a plurality of control channels in each of which a light emitting diode string is controlled. The control circuit has a balancing device for balancing the currents in the individual control channels, and a control unit that is connected to a power factor correction circuit (PFC), to a bridge circuit and to a primary-side current measuring device. Each control channel has a switch for switching the light emitting diode string that is connected to a separate dimming signal. The control circuit furthermore has at least one smoothing capacitor and one current limiter that limits the charging current for the smoothing capacitor. The control unit is additionally designed such that if all the dimming signals are logical ON, the output voltage of the PFC is regulated with the aid of the current measuring device such that the current on the primary side corresponds to a pre-determined setpoint value and that as soon as at least one dimming signal is logical OFF, the output voltage of the PFC is kept constant at its last value (FIG.).

Control circuit for LED backlighting

A down converter for converting an input DC voltage (Vin) into a lower output DC voltage (Vout). The down converter has on the primary side () an LC series resonance circuit () that can be connected via a first switch (S) to the input voltage (Vin) and via a second switch (S) to ground. On the secondary side (), an output switch (S) and an output capacitor (C) are each connected in parallel to the DC voltage output (Vout) and connected to each other through an inductor (L). The output switch (S) is connected via a diode (Dr) to the input voltage (Vin) so as to divert voltage overshoots.

Down converter

An electrical device, particularly having at least one lighting system having light emitting diodes, such as a television having LED backlighting (), which has a stand-by mode (ZPM) with very low power consumption in which only one control unit () is supplied with power via a capacitive voltage divider. For this purpose, alongside parts of the power supply unit (), the interference suppression capacitor () is also switched off.

Electric device having low power consumption in the stand-by state

An electrical device having at least one interference suppression capacitor () that is actively discharged when there is an interruption to the mains voltage () by connecting an electrical load () in parallel. For this purpose, the device has a monitor for the mains voltage () and means for connecting () the electrical load.

Electric device having an interference suppression capacitor circuit

A DC power supply () having a series regulator () for generating a fixed output DC voltage (VCC) at a variable input AC voltage (VAC) with low power loss. For this purpose, the DC power supply () has a transformer () having at least two auxiliary windings (W, W) having different numbers of windings that can each be connected via a switching device () to the series regulator (). Switching is effected such that the power loss is kept as low as possible.

DC power supply with low power loss

A control circuit () for light emitting diode arrangements (), used particularly for backlighting LC flat screens. The circuit has a plurality of control channels (') in each of which one or more light emitting diode arrangements () are disposed. The circuit has a balancing device () which allows currents in the individual control channels (&#x2032;) to be balanced. Each control channel (&#x2032;) has a separate dimming device () through which a brightness of the light emitting diode arrangements () in this control channel (&#x2032;) can be changed separately from the other control channels (&#x2032;). For this purpose, the control circuit has a compensation device () which allows a flow of current in the individual control channels (&#x2032;) to be balanced when the light emitting diodes have different brightnesses.

Control circuit for light emitting diode arrangements

A method and a device for controlling gas discharge lamps using a direct current/alternating current inverter (DC/AC inverter) that is operated at a predetermined frequency and that generates an AC output voltage U for operating the gas discharge lamps from a DC input voltage which has a residual ripple. The DC/AC inverter is operated in zero voltage switching (ZVS) mode, wherein the DC input voltage is used as the control variable for the lamp current I, wherein fluctuations in the lamp current Icaused by the residual ripple of the DC input voltage are compensated by a variation in the switch-on times and/or switch-off times of the switching elements Q, Qof the DC/AC inverter.

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Munich, Germany

Mykhaylo Raykhman