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:
Apr. 25, 2000
Filed:
Feb. 10, 1998
Hajime Nakajima, Tokyo, JP;
Masahiro Shikai, Tokyo, JP;
Toru Oka, Tokyo, JP;
Toshiro Nakashima, Tokyo, JP;
Kazuo Takashima, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A detecting unit provided with an optical system is disposed away from a control unit formed by an electric circuit and an optical transmission/receiving means, and the detecting unit and the control unit are coupled through a transmission optical fiber. The control unit transmits to the detecting unit through the optical fiber a light wave which was subjected to the intensity modulation by a sinusoidal wave of a predetermined frequency. The transmitted light wave is branched into at least two branched optical paths within the detecting unit thereby to perform the phase modulation as to the respective light waves. The light waves passed through the respective branched optical paths are subjected to the phase modulation by the sinusoidal waves which differ in phase 1/4 period by 1/4 period from one another according to a position on a straight line or a rotation angle of a subject to be detected. Then, the light waves thus subjected to the intensity modulation are coupled to a single transmission optical fiber through the branched optical paths and transmitted to the control unit through the transmission optical fiber. In the control unit, the modulated light wave is received and subjected to the phase detection, thereby to calculate and output the position and the rotation angle in accordance with the phase modulation amount of the received light wave.