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:
Mar. 09, 1993
Filed:
Feb. 26, 1992
Applicant:
Inventor:
Osamu Myohga, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
310316 ; 310317 ; 310323 ; 318116 ;
Abstract
An ultrasonic motor driver includes a voltage-current phase difference detector for detecting a phase difference between an applied voltage and a current of a torsional vibration piezoelectric element and a phase shifter for adjusting phases of voltages applied to the longitudinal and torsional vibration piezoelectric elements so that the phase difference is minimum. Even if changes in application environment, e.g., an external force or temperature, occur, a rotational speed can be kept stable to drive an ultrasonic motor.