DC-AC converter circuit using resonating multi-layer piezoelectric transformer

• US 6,052,300 A
• Filed: 05/26/1999
• Issued: 04/18/2000
• Est. Priority Date: 11/09/1998
• Status: Expired due to Fees

• Current Assignee: Face International Corp.
• Original Assignee: Face International Corp.
• Inventors: Boyd, Clark Davis, Bishop, Richard Patten
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Patel, Rajnikant B.
• Application Number:
  US09/318,967
• Time in Patent Office: 328 Days
• Field of Search: 363/131, 363/18, 363/19, 363/97, 323/299, 310/359, 310/316
• US Class Current: 363/131
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H05B 41/2822 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H10N 30/804 for piezoelectric transformers conversion of DC or AC power H02M; for operating discharge lamps H05B41/282
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

DC-AC voltage transformation circuits are provided which use a resonating piezoelectric transformer along with complementary circuit components, to efficiently convert a DC first voltage to a transformer-output AC second voltage. In the preferred embodiment of the invention, A High Displacement Piezoelectric (HDP) transformer achieves sufficiently high voltage output to "cold fire" a gas discharge lamp. The disclosed circuit may be modified using conventional electrical sub-circuitry to pre-heat the cathodes of the lamp. The transformer circuit may be a "self resonating" circuit which relies on an initial pulse from turning on the DC power supply to cause the transformer to begin resonating. In a modified voltage converter circuit, the circuit is not "self resonating" and instead has a phase shift oscillator sub-circuit that provides small pulse signals to start the transformer resonating when the circuit is initially turned on.

Claims

1. A voltage converter circuit comprising:

a resonant sub-circuit;

said resonant sub-circuit comprising a transformer device;

said transformer device having an input portion and output portion,

said input portion comprising an electroactive layer disposed between a first electrode layer and a second electrode layer; and

said output portion comprising a third electrode layer adjacent an electroactive layer;

said resonant sub-circuit further comprising an inductor (L1) electrically connected in parallel with said input portion (1A) of said transformer device between said first electrode layer (4) and said second electrode layer (6);

a first conductor adapted to be connected to a DC first voltage;

a second conductor adapted to be connected to a DC second voltage, said DC first voltage being greater than said DC second voltage;

said first conductor being electrically connected to said first electrode (4) and to a first end of said inductor (L1);

a switching device (Q1),

said switching device having a control input conductor (G), a first switch terminal (D) and a second switch terminal (S);

said first switch terminal (D) being electrically connected to said second electrode layer;

said second switch terminal (S) being electrically connected to said second conductor;

a first resistor (R1) in parallel with said inductor (L1), said first resistor being electrically connected at a first end to said inductor (L1) and said first conductor and said first electrode, and said first resistor being electrically connected at a second end to said control input conductor (G) of said switching device (Q1);

a second resistor (R2) in parallel with said switching device (Q1), said second resistor being electrically connected at a first end to said control input conductor (G) of said switching device (Q1), and said second resistor being electrically connected at a second end to said second terminal (S) of said switching device (Q1);

and a first output conductor connected to said third electrode;

whereby a DC voltage potential applied between said first conductor and said second conductor may be converted to an AC voltage potential between said first output conductor and second switch terminal (S).

2. The circuit according to claim 1, further comprising an oscillator sub-circuit, said oscillator sub-circuit comprising an oscillator switch (Q2), said oscillator switch having an oscillator switch first terminal (C) and an oscillator switch second terminal (E) and an oscillator switch input control conductor (B);

and further comprising a third resistor (R3) electrically connected at a first end to said first conductor (65) and at a second end to said oscillator switch first terminal (C);

a first capacitor (C2) electrically connected at a first end to said oscillator switch second terminal (E) and at a second end to said control input conductor (G) of said switching device (Q1);

and further comprising a feedback conductor electrically connecting said first output conductor with said oscillator switch input control conductor (B).