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:
Jan. 11, 2000
Filed:
Mar. 30, 1999
Takashi Noma, Moriyama, JP;
Yasuyuki Morishima, Kyotanabe, JP;
Abstract
A boosting drive circuit includes first and second series combinations of a coil and a transistor. The two series combination of a coil and a transistor are connected in parallel. The middle points between the coils and the transistors are connected to respective primary electrodes of a piezoelectric transformer. The transistors are alternately operated with a two-phase drive circuit. Thus, a boosting drive circuit providing for the class 'semi-E' operation is formed. A driving voltage control circuit controls an average voltage applied to the input terminal of the boosting drive circuit to ensure that current on the secondary electrode side of the piezoelectric transformer is controlled at a predetermined value is provided between the input power supply and the boosting drive circuit. A driving frequency control circuit changes the driving frequency of the transistors in the boosting drive circuit in such a manner that the phase difference between an alternating voltage applied to the primary electrodes of the piezoelectric transformer and an alternating current flowing in the load is controlled at a predetermined value.