Title:
ABSOLUTE POSITION ENCODER
Document Type and Number:
WIPO Patent Application WO2004079320
Kind Code:
A3
Abstract:
A position encoder (200) uses a track (202) encoded with a pattern of bit-widths (203) 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 (204, 206) 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 (208, 210). The pick-off signals are summed and a bit value is produced. This value 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 2N bits, the position may be an absolute position when the number of valid bits in the shift data register is a least N. The position may be an incremental position when the number of transitions detected is less than N.
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Inventors:
WILLILAMS DARIN S
WRIGGLESWORTH WALTER
WRIGGLESWORTH WALTER
Application Number:
PCT/US2004/005521
Publication Date:
May 06, 2005
Filing Date:
February 26, 2004
Export Citation:
Assignee:
RAYTHEON CO (US)
International Classes:
G01D5/249; G01D5/347; (IPC1-7): G01D5/347
Foreign References:
| US6327791B1 | 2001-12-11 | |||
| DE4436784A1 | 1995-04-27 | |||
| DE19813803C1 | 2000-01-05 | |||
| US6459389B1 | 2002-10-01 | |||
| US5898421A | 1999-04-27 |
Other References:
PATENT ABSTRACTS OF JAPAN vol. 1996, no. 06 28 June 1996 (1996-06-28)
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