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:
Jul. 22, 1997
Filed:
May. 22, 1996
Masahiro Inaniwa, Hitachinaka, JP;
Shinji Watanabe, Hitachinaka, JP;
Tsutomu Takamura, Hitachinaka, JP;
Noriyasu Matsufuji, Hitachinaka, JP;
Takahiro Fujimaki, Hitachinaka, JP;
Hitachi Koki Co., Ltd., , JP;
Abstract
A centrifugal protection apparatus including: a rotor having markers connected to a motor responsive to drive signals; first and second detectors for detecting the marker upon rotation of the rotor and generating first and second detection signals respectively; a drive circuit responsive to a command for generating the drive signals from the supply power via input terminal in response to the first or second detection signal; first and second switch circuits, arranged in series between the input terminal and the motor, for controlling the supply of the drive signals to the motor; a current detector for detecting a current of one of the drive signals and generating a current detection signal; and first and second judging portions for detecting whether the first and second detection signals are within a predetermined value and for operating the first and second switch circuits to cut off the drive signals when the first and second detection signals are not within the predetermined value respectively and when a magnitude of the current detection signal is larger than the predetermined value when the second detection signal is not generated. The first and second judging portions, first and second detectors, and the current detector operate in parallel and independently. The first and second switch circuits are arranged in series to provide more dependable protection.