| US 7,579,749 B2 | ||
| Power supply device and image forming apparatus using the power supply device | ||
| Hiroki Murata, Sunto-gun (Japan); Teruhiko Namiki, Mishima (Japan); Osamu Nagasaki, Numazu (Japan); Atsuhiko Yamaguchi, Izu (Japan); Tomohiro Nakamori, Yokohama (Japan); Takehiro Uchiyama, Sunto-gun (Japan); and Kouji Yasukawa, Susono (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Jul. 06, 2006, as Appl. No. 11/456,049. | ||
| Claims priority of application No. 2005-200646 (JP), filed on Jul. 08, 2005. | ||
| Prior Publication US 2007/0007855 A1, Jan. 11, 2007 | ||
| Int. Cl. H01L 41/08 (2006.01) | ||
| U.S. Cl. 310—316.01 [310/317] | 22 Claims |
| 1. A power supply device that generates an output voltage by driving a piezoelectric transformer using a frequency signal,
comprising:
a comparison unit configured to compare an output voltage and a voltage setting signal that sets the output voltage; and
a voltage control oscillation unit configured to generate the frequency signal to drive the piezoelectric transformer based
on comparison results of the comparison unit,
wherein frequency characteristics of the piezoelectric transformer when driving the piezoelectric transformer using the frequency
signal include a resonant frequency of the piezoelectric transformer at which a maximum voltage is output and a plurality
of spurious resonant frequencies of the piezoelectric transformer, the plurality of spurious resonant frequencies being higher
than the resonant frequency and at which a voltage lower than the maximum voltage is output, and
wherein the voltage control oscillation unit generates the frequency signal within a range between the resonant frequency
and a closest spurious resonant frequency to the resonant frequency among the plurality of spurious resonant frequencies,
sets an initial frequency of the frequency signal for driving the piezoelectric transformer to be lower than the closest spurious
resonant frequency, and sweeps a frequency from the set initial frequency to a frequency corresponding to a target voltage.
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