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. 29, 2005
Filed:
Dec. 11, 2003
Yoshikazu Kawano, Hitachinaka, JP;
Nobuhiro Takano, Hitachinaka, JP;
Yuuichi Satou, Hitachinaka, JP;
Toshihiko Tachibana, Hitachinaka, JP;
Yoshikazu Kawano, Hitachinaka, JP;
Nobuhiro Takano, Hitachinaka, JP;
Yuuichi Satou, Hitachinaka, JP;
Toshihiko Tachibana, Hitachinaka, JP;
Hitachi Koki Co., Ltd., Tokyo, JP;
Abstract
A rotational speed controller maintains a constant low speed during idling, a constant high speed when a load is applied and controls motor rotational speed in the range between low and high speed to ensure safe operation when used in an electrically powered tool. When the current detection signal output from a current detection circuit is lower than a first predetermined value (during idling), a rotational speed setting circuit outputs a rotational speed setting signal indicating a first rotational speed to drive the motor at a constant low speed. When the current detection signal exceeds a second predetermined value (when a load is applied), the rotational speed setting circuit outputs a rotational speed setting signal indicating the second rotational speed to drive the motor at a constant high speed. When the current detection signal output from the current detection circuit is between the first and second predetermined values, the rotational speed setting circuit outputs a rotational speed setting signal indicating a motor rotational speed that is roughly proportional to the current detection signal level.