Regulated electroluminescent panel power supply
AssigneeAbbott Laboratories
InventorArie Ravid
Life of this patent
Estimating the term…
Abstract
A power supply that converts an unregulated DC voltage source to a regulated AC power source suitable for energizing an electroluminescent panel. The DC voltage source powers a DC-to-AC inverter to generate an AC output. A feedback circuit monitors the AC output and compensates for any changes in amplitude that arise due to fluctuations in the DC input voltage. A single reference voltage is used to both selectively energize and deenergize the circuit and to control the amplitude of the AC output.
Claims20
A power supply for an electroluminescent panel that is driven by an unregulated direct current (DC) voltage source, said power supply comprising:
- (a) a variable frequency oscillator connected to an electroluminescent panel having a characteristic capacitance, said oscillator generating a continuous, alternating current (AC) voltage having a frequency that varies in response to a change in the capacitance of the electroluminescent panel and an amplitude that varies in response to a level of DC that is coupled to an input of the oscillator,
- (b) a transformer having a plurality of windings and comprising an inductive portion of the oscillator, said transformer stepping-up the AC voltage generated by the oscillator to an amplitude suitable to drive the electroluminescent panel;
- and
- (c) a feedback circuit connected between one of the plurality of windings of the transformer and the input of the oscillator, said feedback circuit including a rectifier for rectifying an AC signal on said one of the plurality of windings, producing a corresponding rectified signal and controlling the level of DC that is coupled to the input of the oscillator in response to the rectified signal, to adjust the amplitude of the AC voltage generated by the oscillator if it varies due to fluctuations in the unregulated DC voltage source input to the power supply in order to maintain a stable light level from the electroluminescent panel.
A power supply for an electroluminescent panel having a characteristic capacitance, said power supply being driven by an unregulated DC voltage source, said power supply comprising:
- (a) a transformer including a plurality of input windings, said plurality of windings including a first input winding that is connected to an unregulated DC voltage source, a second input winding that is connected to the unregulated DC voltage source and is driven by a current source, and an output winding that produces a stepped-up AC voltage;
- (b) an oscillator having a resonant frequency determined at least in part by the capacitance of the electroluminescent panel and an inductance of the output winding of the transformer;
- (c) a rectifier connected to the output winding of the transformer and generating a rectified signal from the AC voltage produced by the output winding of the transformer;
- and
- (d) a comparator with a first input, a second input, and an output, said first input being connected to the rectified signal, said second input being connected to a reference voltage level, and said output being connected to the current source to control an amplitude of the stepped-up AC voltage produced by the output winding of the transformer, to maintain a stable light level output from the electroluminescent panel.
A power supply that is driven by an unregulated DC voltage source, said power supply energizing an electroluminescent panel and comprising:
- (a) oscillator means for generating a continuous, AC signal having a frequency that varies in response to a change in capacitance of an electroluminescent panel and an amplitude that changes in response to a control signal that is coupled to an input of the oscillator means;
- (b) transformer means for stepping-up the AC signal generated by the oscillator, producing an AC output voltage with an amplitude suitable to drive the electroluminescent panel;
- and
- (c) control means for monitoring the AC output voltage of the transformer means and for producing the control signal that is coupled to the input of the oscillator means, said control means including a rectifier that is coupled to the transformer means to produce a rectified signal corresponding to the AC output voltage, said control signal controlling the amplitude of the AC output of the transformer means as a function of the rectified signal and a reference signal if the AC output varies due to fluctuations in the unregulated DC voltage source input to the power supply, in order to maintain a stable light level output from the electroluminescent panel.
Dependencies are inferred from the claim text.