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. 23, 1991
Filed:
Mar. 22, 1989
Alfons Spies, Seebruck, DE;
Dr. Johannes Heidenhain GmbH, Traureut, DE;
Abstract
A position measuring arrangement is disclosed which comprises a three-grid measuring system. A first grid is illuminated under an angle .alpha.. Two partial beams result from diffraction on the first grid. the two partial beams impinge on a second grid, which may be the scale of the position-measuring arrangement. Diffraction of the partial-beams on the second grid result in four partial-beams of which the two partial-beams lying closest to the grid normal impinge upon a third grid. The third grid again diffracts the partial-beams and brings them into interference. The partial-beams which are intensity-modulated by interference by the third grid impinge upon photodetectors, by which they are transformed into phase-shifted electric signals and fed to and evaluated arrangement.