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. 07, 2017
Filed:
Feb. 27, 2014
Adamant Co., Ltd., Tokyo, JP;
Yoshihiro Konno, Tochigi, JP;
Masaru Sasaki, Kawaguchi, JP;
ADAMANT CO., LTD., Tokyo, JP;
Abstract
Current measuring device keeps fluctuation range for the ratio error in output within ±0.5% range and simplified assembly thereof. The measuring device includes at least a light entrance and exit, optical fiber for a sensor, Faraday rotator, first and second ¼-wavelength plates, polarization separator, light source, and signal-processing-circuit including a photoelectric-conversion-element. Optical fiber for a sensor has birefringence and includes one end wherein two circularly polarized light-beams having different rotation enter directions and another end reflects circularly polarized light-beams entered. Phase difference of two linearly polarized light-beams in the round-trip light path between two ¼-wavelength plates is compensated, and the Faraday rotational angle when the Faraday rotator is magnetically saturated set to 22.5°+α° so fluctuation range for ratio error in measured value of the current to be measured is set in range, ±0.5%. The crystal-axes on optical faces of two ¼-wavelength plates are set to be perpendicular or same direction.