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:
Jun. 20, 2000
Filed:
Feb. 24, 1999
Naoki Furuhashi, Tokyo, JP;
Shuuji Yamaguchi, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A piezoelectric transformer driving circuit and method can prevent degradation of characteristics of a piezoelectric transformer. A repetition frequency of a drive voltage lower than a predetermined value, sweeping range narrower than a predetermined range and an output voltage of the piezoelectric transformer higher than a predetermined reference value are detected by a load current comparing circuit and an output voltage comparing circuit. In response to the results of the comparisons, a sweeping range varying means varies the repetition frequency to be higher than an upper limit value of the sweeping range in a frequency sweeping oscillator. By variation, the sweeping of the output voltage of the piezoelectric transformer is initiated from a small value to correct an effective value of a piezoelectric transformer vibration velocity to prevent degradation of characteristics of the piezoelectric transformer.