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:
May. 21, 2013
Filed:
May. 27, 2011
Akihiro Kuroda, Isehara, JP;
Akihiro Kuroda, Isehara, JP;
Mori Seiki & Co., Ltd., Nara, JP;
Abstract
A position detection device in which 2nd-order or higher order diffracted light as well as stray light is suppressed from being generated to improve the S/N ratio of a position detection signal as well as to improve detection accuracy. With a pitch d of a diffraction grating, whose grating surfaceis covered with a protective layerof a refractive index n, and with a wavelength λin vacuum of coherent light illuminated, d<2λ/n is set. An angle of incidence θof the coherent light on the diffraction gratingis set to satisfy the following relationship: |sin θ|<(2λ/dn)−1. The 1st order diffracted light is used for position detection.