DC/AC and DC/DC power supply for LCD displays
AssigneeDelphi Technologies, Inc.
InventorsAndrew Michael Voto, Robert Martin Voto
Life of this patent
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Abstract
A voltage power supply circuit is provided that uses the voltage output of an oscillator to provide a high voltage DC output to drive a liquid crystal display device. A controller IC opens and closes an FET to allow the EMF of an inductor to generate a DC voltage that exceeds the battery voltage source for the liquid crystal display device. Accordingly, the oscillator circuit that drives a back light display for a liquid crystal device is simultaneously used to generate the high voltage DC source for the liquid crystal display device.
Claims20
A voltage power supply circuit comprising:
- an oscillator circuit that provides a voltage output;
- an inductor in series with the voltage output of the oscillator circuit;
- a switch positioned in series with the inductor and the voltage output of the oscillator circuit, the switch being positioned between the inductor and a ground;
- a DC circuit electrically connected to a high potential side of the switch;
- and
- a battery voltage source supplying voltage to the oscillator circuit;
- wherein the inductor generates an EMF when the switch does not conduct to create a voltage in the DC circuit that exceeds a voltage level of the battery voltage source.
A voltage power supply circuit for a liquid crystal display system comprising:
- a Royer oscillator having a voltage output;
- an inductor in series with the voltage output of the Royer oscillator;
- a FET in series with the inductor and the voltage output, the FET positioned at a low potential side of the inductor;
- a controller IC controlling voltage supplied to a gate of the FET for turning the FET on and off at a predetermined frequency;
- a DC voltage circuit electrically connected to a position between the inductor and the FET;
- an AC voltage circuit driven by the Royer oscillator;
- a cold cathode fluorescent lamp driven by the AC voltage circuit;
- a LCD glass, a voltage across the LCD glass being selectively driven by the DC circuit;
- a battery voltage source supplying battery voltage to the Royer oscillator;
- and
- a clamping circuit connected between the DC voltage circuit and the battery voltage source that clamps the DC voltage circuit to a level above a voltage level of the battery voltage source;
- wherein EMF generated by the inductor when the controller IC closes the FET generates a voltage in the DC voltage circuit that exceeds the voltage level of the battery voltage source.
An improved voltage power supply for a liquid crystal display device of the type that provides a DC voltage across an LCD glass and an AC voltage to drive a back light display for the liquid crystal display device, the improvement comprising:
- an oscillator circuit that provides a voltage output and drives an AC circuit;
- an inductor in series with the voltage output of the oscillator circuit;
- a switch positioned in series with the inductor and the voltage output of the oscillator circuit, the switch being positioned between the inductor and a ground;
- a DC circuit electrically connected to a high potential side of the switch;
- and
- a battery voltage source supplying voltage to the oscillator circuit;
- wherein the inductor generates an EMF when the switch does not conduct to create a voltage in the DC circuit that exceeds a voltage level of the battery voltage source.
An LCD device comprising:
- A voltage power supply circuit for generating a high AC voltage and a high DC voltage to a liquid crystal display of the LCD device, the voltage power supply circuit comprising:
- an oscillator circuit that provides a voltage output;
- an inductor in series with the voltage output of the oscillator circuit;
- a switch positioned in series with the inductor and the voltage output of the oscillator circuit, the switch being positioned between the inductor and a ground;
- a DC circuit electrically connected to a high potential side of the switch;
- and
- a battery voltage source supplying voltage to the oscillator circuit;
- wherein the inductor generates an EMF when the switch does not conduct to create a voltage in the DC circuit that exceeds a voltage level of the battery voltage source.
Dependencies are inferred from the claim text.