US 5,866,969 A · Actuating circuit of piezoelectric transformer and actuating method thereof

Abstract

An actuating circuit of a piezoelectric transformer which is small in thickness and size and has a wide input voltage range is developed. In the actuating circuit of the piezoelectric transformer, when a sine wave outputted from a AGC circuit is input to a delta-sigma modulator, the sine wave switches output driver and switches a second output driver through an invertor with a 1-bit quantized bit signal so as to generate a pulse signal having an amplitude of power supply voltage Vdd from the GND potential. Actuating waves output from the output drivers and are applied to 1 piezoelectric transformer extracting resonance frequency of a piezoelectric transformer through a filtering effect provided with an input capacitance of the piezoelectric transformer and coil converting the 1-bit quantized bit signal into a sine wave. Consequently, since the piezoelectric transformer can be operated with the sine wave, the piezoelectric transformer can be actuated efficiently.

Claims12

Dependent claims

An actuating method of a piezoelectric transformer which outputs a voltage from secondary terminals, actuated by a voltage input to primary terminals, comprising the steps of:

generating an analog high frequency voltage;
converting said high frequency voltage to a digital signal;
converting said digital signal into a first high frequency voltage having a predetermined amplitude whose frequency is proximal to the resonance frequency of the piezoelectric transformer and an inverted high frequency voltage which has opposite phase to the first high frequency voltage having the same predetermined amplitude;
applying the first high frequency voltage to a primary electrode of the piezoelectric transformer;
extracting the output high frequency current from the secondary electrode of the piezoelectric transformer;
applying the first high frequency voltage to a primary electrode of the piezoelectric transformer;
extracting the output high frequency current from the secondary electrode of the piezoelectric transformer;
converting the extracted high frequency current into a high frequency voltage;
and
feeding back the high frequency voltage to the A/D converting step.

7 more elements

An actuating circuit of a piezoelectric transformer which outputs a voltage from a secondary terminal, actuated by a voltage input to primary terminals comprising:

a frequency sweeping oscillating circuit for generating a pulse signal of a second frequency higher than twice a first frequency which is the resonance frequency of the piezoelectric transformer;
a frequency divider circuit for dividing the pulse signal into the first frequency of said piezoelectric transformer;
a first band-pass filter for passing a sine wave of the first frequency of an output of said frequency divider circuit;
a delta-sigma modulator for converting the sine wave into a 1-bit quantized bit signal by oversampling the sine wave with the second frequency;
a first output driver for converting the output of the delta-sigma modulator to a first actuating high frequency voltage having amplitude of predetermined dc power to input into a first primary electrode of the piezoelectric transformer;
and
a second output driver for converting the output of the delta-sigma modulator to an opposite phase actuating high frequency voltage having the same amplitude but opposite phase to the first actuating high frequency voltage to input a second primary electrode of the piezoelectric transformer.

4 more elements

Dependencies are inferred from the claim text.

Actuating circuit of piezoelectric transformer and actuating method thereof

Life of this patent

Actuating circuit of piezoelectric transformer and actuating method thereof

Life of this patent

Abstract

Claims12