Patent ID: 7196475

Claim:
A piezoelectric-transformer high-voltage power supply in combination with an image-forming apparatus which includes a latent-image forming section configured to form an electrostatic latent image on an image carrier, a developing section configured to form a toner image on the electrostatic latent image, and a transfer section configured to transfer the toner image onto a transfer material, the piezoelectric-transformer high-voltage power supply comprising: a piezoelectric transformer; a piezoelectric-transformer drive circuit; an output-voltage setting-signal output circuit configured to output an output-voltage setting-signal; an output-voltage detector circuit; and a drive control circuit configured to output a control signal on the basis of a signal from the output-voltage detector circuit and the output-voltage setting-signal, for controlling the piezoelectric-transformer drive circuit, wherein the output-voltage setting-signal output circuit is configured to output an output-voltage setting-signal corresponding to a voltage lower than a target voltage, and then output another output-voltage setting-signal corresponding to the target voltage.