Piezoelectric transformer driving device controlled by variable reference voltage values and image forming device

A piezoelectric transformer driving device, comprising:

• a piezoelectric transformer with a certain resonance frequency configured such that when an input voltage is intermittently applied to a primary side, an alternating high voltage is output from a secondary side;
• a switching part configured to generate the input voltage by switching based on a control signal having a control frequency, and configured to supply the voltage to the piezoelectric transformer;
• a switching control part configured to control the control frequency of the control signal based on a comparison result, and configured to supply the control signal to the switching part;
• a reference voltage waveform generation part configured to switch between a first voltage value as a target value, a second voltage value that is lower than the first voltage value, and a third voltage value that is higher than the first voltage value, within a given unit time so that a reference voltage waveform is generated;
• a monitor voltage generation part configured to generate a monitor voltage waveform based on the high voltage output from the piezoelectric transformer;
• and
• a comparison part configured to compare the reference voltage waveform with the monitor voltage waveform to generate the comparison result, and configured to supply the comparison result to the switching control part, wherein
• the first voltage value is a constant voltage value over a certain period of time,
• a triangle wave voltage value is formed by the second voltage value and the third voltage value, and
• the first voltage value and the triangle wave voltage value are exchanged when the triangle wave voltage value reaches the first voltage value.

A piezoelectric transformer driving device, comprising:

• a piezoelectric transformer with a certain resonance frequency configured such that when an input voltage is intermittently applied to a primary side, an alternating high voltage is output from a secondary side;
• a switching part configured to generate the input voltage by switching based on a control signal having a control frequency, and configured to supply the voltage to the piezoelectric transformer;
• a switching control part configured to control the control frequency of the control signal based on a comparison result, and configured to supply the control signal to the switching part;
• a reference voltage waveform generation part configured to switch between a first voltage value as a target value, a second voltage value that is lower than the first voltage value, and a third voltage value that is higher than the first voltage value, within a given unit time so that a reference voltage waveform is generated;
• a monitor voltage generation part configured to generate a monitor voltage waveform based on the high voltage output from the piezoelectric transformer;
• a comparison part configured to compare the reference voltage waveform with the monitor voltage waveform to generate the comparison result, and configured to supply the comparison result to the switching control part;
• a divider part configured to divide a clock signal;
• and
• a divider ratio setting part configured to set a divider ratio for the clock signal, wherein
• the divider ratio setting part has an integer part and a fractional part, and
• the fractional part is binarized by a binarization part and is added to the integer part so that the frequency is controlled by the divider ratio per unit time as a first dividing and a second dividing.