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:
Feb. 22, 2000
Filed:
Sep. 30, 1997
Yasuhei Shimada, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In a steady-state operation, a rectified voltage obtained from an output current Io of a piezoelectric transformer 1 is compared in a comparator 10 with Vref. When the voltage is lower than Vref, a signal Vdown is at an 'H' level, and otherwise it is at an 'L' level. A switch SW1 or SW2 is thus turned on to charge or discharge a capacitor Cvco. This has an effect of sweeping the oscillation frequency of a VCO 14 downward or upward to increase or reduce the output voltage Vo of the piezoelectric transformer 1 which is driven at the oscillation frequency. When a load 2 is open-circuited, a voltage VR obtained from an output voltage Vo becomes higher than Vmax to set a flip-flop 13 and turn on a switch SW3. The capacitor voltage Vvco is thus reduced to reduce the oscillation frequency of the VCO 14 and reduce the output voltage Vo. When the voltage VR becomes lower than Vmin, the flip-flop 18 is reset by the output of the comparator 16 to turn off the switch SW3.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile