The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 29, 2003
Filed:
Aug. 31, 2001
Nobuyasu Kanekawa, Hitachi, JP;
Kohei Sakurai, Hitachi, JP;
Kenji Tabuchi, Hitachinaka, JP;
Mitsuru Watabe, Urizura, JP;
Shoji Sasaki, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In order to ensures a stable reduction of noise level at all times, in the steps of switching input voltage with a switching element smoothing the voltage of rectangular wave obtained by switching with a reactor L and capacitor Cf and outputting it, the voltage obtained by dividing the output voltage is compared with the sawtooth wave output from a sawtooth wave generator by a comparator . When the switching signal in response to the result of this comparison is applied to the switching element the counter is actuated synchronously with the vertex of the sawtooth wave to perform opening/closing operation of the switch SW . The time constant of the time constant circuit comprising a R and C is adjusted according to whether a resistor R is present or not, and the signals of frequencies f and f coming out of the sawtooth wave generator are sequentially switched to be sent to the comparator . The peak of the switching noise is diffused in the frequency range by sequential selection of switching frequencies, and noise level is reduced by diffusion of noise energy.