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. 25, 1994
Filed:
Jun. 28, 1993
Masaru Nyui, Tokyo, JP;
Masahiko Igaki, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
Disclosed is a Talbot's interference type optical encoder constructed so as to minimize a measurement error due to a signal distortion. A semiconductor laser is installed so that a vertical transverse mode is set in a direction vertical to a moving direction of a diffraction grating serving as a scale. Further, a stop for regulating light beams from a light source is prepared. An aperture of this stop assumes such a configuration that a dimension in a direction along the moving direction of the scale diffraction grating is set equal to or shorter than a dimension in a direction vertical to the moving direction of the scale diffraction grating. Distortions of signals obtained are thereby reduced. A comparison level in signal processing can be centered on an amplitude of the signal, and, as a result, an occurrence of error can be prevented.