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:
Dec. 13, 2011
Filed:
Mar. 24, 2009
Takao Ohsawa, Tokyo, JP;
Takao Ohsawa, Tokyo, JP;
Sony Corporation, , JP;
Abstract
A drive device for a piezoelectric element includes a transformer, a driver circuit, and a control circuit. The transformer has a primary side and a secondary side. The drive circuit causes the secondary side to generate a drive signal whose frequency varies in accordance with a control signal input to the primary side and to supply the generated drive signal to the piezoelectric element. The control circuit changes a frequency of the control signal in a predetermined frequency range multiple times, detects an impedance change in the piezoelectric element each time the control-signal frequency is changed, determines a resonant frequency of the piezoelectric element on the basis of a transition of the impedance change, and controls the control-signal frequency so that the determined resonant frequency is obtained.