| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To make an alternating-current bias means used for detection of a remaining amount of toner by an electrostatic-capacitance detection method small in size and low in cost by applying an alternating voltage outputted from a piezoelectric-transformer high voltage power source to a developing unit. <P>SOLUTION: The image forming apparatus has the alternating-current high-voltage power supply. The alternating-current high-voltage power supply used for the alternating-current bias means for detection of a remaining amount of toner includes a piezoelectric transformer, a piezoelectric-transformer driving means, a piezoelectric-transformer driving-signal generating means, an excitation level detecting means, an excitation level setting means, and an controlling means that feeds back a difference signal between a detection level signal supplied from an excitation level detecting means and a setting level signal supplied from the excitation level setting means to the piezoelectric-transformer driving-signal generating means to control an excitation level. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
