Piezoelectric transformer inverter
First Claim
1. A piezoelectric transformer inverter, which drives a load by a piezoelectric transformer, comprising:
- a piezoelectric transformer which has an input electrode and an output electrode and which boosts an AC voltage applied to the input electrode to supply the boosted AC voltage to a load connected to the output electrode;
piezoelectric transformer driving means connected to the piezoelectric transformer to drive the piezoelectric transformer, the piezoelectric transformer driving means having conductive elements, switching elements, and a phase drive circuit into which a pulse voltage signal for driving the switching elements is inputted, and converting an inputted AC voltage into an AC voltage of a substantially constant frequency lower than the inputted voltage to output to the piezoelectric transformer;
phase-difference detecting means for detecting the phase difference between a driving signal for controlling the on-off operation of the switching elements and an output current or an output voltage of the piezoelectric transformer to output a control voltage corresponding to the phase difference; and
frequency controlling means for outputting a pulse voltage signal of a frequency based on the control voltage outputted from the phase-difference detecting means to the phase difference drive circuit of the piezoelectric transformer driving means so that the value of the phase difference can be a desired value.
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Accused Products
Abstract
A piezoelectric transformer inverter can be driven in wide ranges of input voltages and output currents so that a wide range of dimming can be achieved. Furthermore, the piezoelectric transformer inverter can maintain high efficiency in the overall driven ranges thereof so as to yield stable luminance. The above piezoelectric transformer inverter includes a piezoelectric transformer drive unit having conductive elements, switching elements, and a phase drive circuit to convert an inputted AC voltage into an AC voltage having a substantially constant frequency which is lower than the inputted AC voltage and output to a piezoelectric transformer, a phase-difference detecting unit for detecting the phase difference between a drive controlling signal of one of the switching elements and an output current or output voltage of the piezoelectric transformer to output a control voltage corresponding to the phase difference, and a frequency control circuit for outputting a pulse voltage signal of a frequency based on the control voltage to the phase drive circuit of the piezoelectric transformer drive unit.
43 Citations
12 Claims
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1. A piezoelectric transformer inverter, which drives a load by a piezoelectric transformer, comprising:
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a piezoelectric transformer which has an input electrode and an output electrode and which boosts an AC voltage applied to the input electrode to supply the boosted AC voltage to a load connected to the output electrode;
piezoelectric transformer driving means connected to the piezoelectric transformer to drive the piezoelectric transformer, the piezoelectric transformer driving means having conductive elements, switching elements, and a phase drive circuit into which a pulse voltage signal for driving the switching elements is inputted, and converting an inputted AC voltage into an AC voltage of a substantially constant frequency lower than the inputted voltage to output to the piezoelectric transformer;
phase-difference detecting means for detecting the phase difference between a driving signal for controlling the on-off operation of the switching elements and an output current or an output voltage of the piezoelectric transformer to output a control voltage corresponding to the phase difference; and
frequency controlling means for outputting a pulse voltage signal of a frequency based on the control voltage outputted from the phase-difference detecting means to the phase difference drive circuit of the piezoelectric transformer driving means so that the value of the phase difference can be a desired value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification