Fluorescent-lamp excitation circuit using a piezoelectric acoustic transformer and methods for using same

A circuit for operating a fluorescent lamp from a DC power source, the circuit comprising:

• a regulator having an input coupled to the DC power source, an output, and a control terminal for receiving a feedback signal to control current produced at the output;
• a DC-to-AC converter, having a ceramic transformer, coupled to the output of the regulator, for producing at an output terminal an AC signal;
• a coupling element for coupling the lamp to the converter;
• and
• a monitoring element for monitoring a current signal indicative of current conducted by the lamp and for generating a feedback signal indicative of current conducted by the lamp, said feedback signal being coupled to the regulator to cause light to be emitted by the lamp to be regulated.

A circuit for operating a fluorescent lamp from a source of DC power, the circuit comprising:

• a regulator for producing a regulated DC output, the regulator having an input for receiving a feedback signal to control current produced at the DC output;
• a DC-to-AC converter, coupled to the regulated DC output of the regulator, for producing an AC voltage at an AC output;
• a ceramic step-up transformer having a first terminal coupled to the AC output of the converter and having a second terminal coupled to the fluorescent lamp;
• and
• a monitoring element for monitoring current supplied to the fluorescent lamp and generating a feedback signal to regulate light emitted by the lamp.

A circuit for operating a fluorescent lamp from a source of DC power, the circuit comprising:

• a current-mode switching regulator having an input coupled to the source of DC power, an output, and a control terminal adapted for receiving a signal to control current produced at the output;
• an oscillator coupled to the output of the switching regulator, the oscillator producing an AC voltage;
• a ceramic step-up transformer having a first terminal, and a second terminal coupled to the fluorescent lamp, the first terminal being coupled to the oscillator to transform the AC voltage produced by the oscillator to a high AC voltage at the second terminal sufficient to operate the fluorescent lamp;
• and
• a sensing element including an impedance adapted to sense an input current at the input of the switching regulator to generate a feedback signal proportional to the input current, the current-sensing element being coupled to conduct the feedback signal to the control terminal of the switching regulator to regulate current conducted and intensity of light emitted by the fluorescent lamp.

A circuit for operating a fluorescent lamp from a source of DC power, the circuit comprising:

• a current-mode switching regulator having an input coupled to the source of DC power, an output, and a control terminal for receiving a signal to control current produced at the output;
• an oscillator coupled to the output of the switching regulator, the oscillator producing an AC voltage;
• a ceramic step-up transformer having a first terminal, and a second terminal coupled to the fluorescent lamp, the first terminal being coupled to the oscillator to transform the AC voltage produced by the oscillator to a high AC voltage at the second terminal sufficient to operate the fluorescent lamp;
• and
• a current-sensing element including an impedance adapted to sense an input current at the first terminal of the transformer to generate a feedback signal proportional to the input current, the current-sensing element being coupled to conduct the feedback signal to the switching regulator to regulate current conducted and intensity of light emitted by the fluorescent lamp.

A circuit operable from a DC power source, the circuit comprising:

• at least one fluorescent lamp;
• a DC-to-AC converter, having an input coupled to the DC power source, an output, and a control terminal for receiving a feedback signal to control a current indicative of current conducted by the fluorescent lamp;
• a ceramic step-up transformer, coupled to the output of the converter, for producing at an output terminal high-voltage AC sufficient to cause the fluorescent lamp to emit light, the output terminal being coupled to generate a current through the fluorescent lamp;
• and
• a sensing element for sensing current conducted by the fluorescent lamp by monitoring current passing through the converter, for generating a feedback signal indicative of the magnitude of current passing through the fluorescent lamp, and for coupling the feedback signal to the converter to regulate current conducted and intensity of light emitted by the lamp.

A method for operating a fluorescent lamp from a DC power source, the method comprising the steps of:

• converting DC power into AC voltage;
• using a ceramic transformer to convert the AC voltage to a high-voltage AC signal sufficient to generate a current through the fluorescent lamp to cause the fluorescent lamp to emit light;
• sensing current conducted by the fluorescent lamp by monitoring a current indicative of current conducted by the fluorescent lamp during the step of converting;
• generating a feedback signal indicative of the magnitude of the monitored current;
• and
• controlling the conversion of DC power to high-voltage AC in response to the feedback signal to regulate current conducted and intensity of light emitted by the lamp.