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:
Aug. 26, 2003
Filed:
Dec. 05, 2001
Yoshinori Ito, Nagano-ken, JP;
Kazuhiro Hane, Miyagi-ken, JP;
Harmonic Drive Systems, Inc., Tokyo, JP;
Abstract
In an optical linear encoder, light from an LED passes through a moving grating formed in a semiconductor moving plate and is reflected by a reflective grating of a reflective grating plate An image of the reflective grating is detected by photodiodes that are formed in the shape of a grid on the semiconductor moving plate The moving grating and the photodiodes are formed on the same semiconductor substrate with the photodiodes in the form of a grid having a lens effect. Consequently, a lens optical system is not required, making it possible to produce a compact, small-scale encoder. A differential signal for an A-phase signal obtained from a group of photodiodes arranged on the semiconductor substrate and an inverse of this signal is produced as the A-phase signal, and a differential signal for a B-phase signal and an inverse of this signal is produced as the B-phase signal, so that an encoder output with little error can be obtained.