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:
Oct. 03, 2000
Filed:
Jul. 08, 1998
Masanobu Tanaka, Miyagi-ken, JP;
Tatsumaro Yamashita, Miyagi-ken, JP;
Shoichi Kyoya, Miyagi-ken, JP;
Alps Electric Co., Ltd., Tokyo, JP;
Abstract
Light emitted from a light emitting device is reflected by a first reflection curved face so that the travel direction of the light is almost perpendicularly diffused, the light is reflected by a reflection face circumferentially formed on an end face of a rotor in the direction parallel to an axial line, and after that, the light is supplied to a stator side along a cylindrical part on the outer periphery of the rotor. In a stator, light is condensed again in the axial direction by a reflection face and, after that, the light is reflected by a second reflection curved face and is received by a photo sensing device. In this instance, since the light passed through whole slits on the end face of the rotor and whole slits in the peripheral part of the stator is converged and then detected by an FG, the signal level upon detection is increased, the detection accuracy is improved at low cost.