公开(公告)号：US20170309806A1

公开(公告)日：2017-10-26

申请号：US15463920

申请日：2017-03-20

Applicant: TOPCON CORPORATION

Inventor： Kaoru KUMAGAI ,  Satoshi YANOBE ,  Tetsutaro KOUJI

IPC: H01L41/04 ,  G01D5/347 ,  B06B1/06 ,  G01C3/08 ,  H01L41/09 ,  G01S3/786

CPC classification number: H01L41/042 ,  B06B1/0644 ,  G01C3/08 ,  G01C15/002 ,  G01D5/3473 ,  G01S3/786 ,  H01L41/09 ,  H02N2/142 ,  H02N2/163

Abstract: Provided is a method for controlling an ultrasonic motor to reduce noise sounding during low-speed rotation in a surveying instrument adopting the ultrasonic motor for a rotary shaft, and a surveying instrument for the same. In a method for controlling an ultrasonic motor according to an aspect of the present invention, in a low-speed rotation range of an ultrasonic motor, a ratio of an acceleration period as a time of application of the drive signal in a control cycle is controlled, and a time to start the acceleration period is randomly shifted for each control cycle. In a method for controlling an ultrasonic motor according to another aspect, a time to start the acceleration period is regularly shifted for each control cycle. In a method for controlling an ultrasonic motor according to still another aspect, second-half acceleration control and first-half acceleration control are alternately repeated.