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. 25, 2006
Filed:
Mar. 05, 2003
Darin Williams, Tucson, AZ (US);
Walter Wrigglesworth, Tucson, AZ (US);
Darin Williams, Tucson, AZ (US);
Walter Wrigglesworth, Tucson, AZ (US);
Raytheon Company, Waltham, MA (US);
Abstract
A position encoder uses a track encoded with a pattern of bit-widths in accordance with a sequence. The sequence may be any sequence having unique subsequences, and may be a pseudo-random noise (PRN) sequence such that each N-bit subsequence occurs only once on the track. Sensors detect transitions between the bits and bit-widths as the track moves with respect to the sensors to provide in-phase and quadrature-phase pick-off signals. The pickoff signals are summed and absolute value thresholded. The absolute value thresholded sum signal is sampled when the quadrature pairs are in the '00' or '11' quadrants, and latched when the sum signal goes high to distinguish between wide and narrow bit widths. The latch is shifted into a shift data register for use in determining the position of the encoder track. In the case of a PRN sequence having a length of 2bits, the position may be an absolute position when the number of valid bits in the shift data register is at least N. The position may be an incremental position when the number of transitions detected is less than N.