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:
Feb. 16, 1988
Filed:
Dec. 24, 1985
Richard A Hutchin, Marlboro, MA (US);
Novon, Inc., Swampscott, MA (US);
Abstract
A system for determining the position of an object in which a moving periodic pattern is projected onto the object. A sensor on the object generates a sensor signal related to the periodic pattern. A reference signal is generated relating to the position of the moving periodic pattern. The sensor signal and the reference signal are compared to determine the position of the object. The pattern may be generated by projecting light through two gratings which are separated and have the same pattern. Errors created by instability or nonisotropy can be corrected employing a third grating having a different pattern and generating a correction value related to the difference between the position of the object determined employing the pattern generated by the two gratings and the pattern generated by the third grating. The moving nature of the pattern may be created by employing a fixed projector and a moving mirror. The reference signal may be generated by a sensor in the field of the moving periodic pattern fixed with respect to the coordinate system in which the position of the object is determined or by monitoring the position of the rotating mirror.