Title:
ROTARY ABSOLUTE ENCODER WITH ERROR CORRECTION DETECTION FUNCTION
Document Type and Number:
Japanese Patent JP3175054
Kind Code:
B2
Abstract:
PURPOSE: To locate a sensor causing a read error and to raise an alarm in the case of two sensors causing simultaneous read error by arranging number of sensors at which all read binary numbers have inter-Humming distance of 4 or more to a detection section for the purpose of discrimination.
CONSTITUTION: Sensors S1-S13 are arranged along a pattern T of a detection section B moved relatively with respect to a code plate A. A discrimination circuit C discriminates a binary number read from the sensors, and outputs respectively a signal c1 in the case of no read error, a sensor location signal c2 in the case of one read error and an alarm signal c3 in the case of two-read errors. A 2nd discrimination circuit D collates a binary number read by each sensor with an equation of X5+X4+X2+X+1=0 and outputs respectively a signal d1, a sensor location signal d2, and an alarm signal d3 depending on the cases of no read error, one sensor read error and two-sensor read error. A distance detection circuit E checks each output of the discrimination circuits C, D and outputs respectively a signal e1, a sensor location signal e2, and an alarm signal e3 depending on the cases of no read error, one sensor read error and two-sensor read error, then the occurrence of an error is recognized.
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Inventors:
Yasushi Ohno
Go Matsumoto
Go Matsumoto
Application Number:
JP6380491A
Publication Date:
June 11, 2001
Filing Date:
March 06, 1991
Export Citation:
Assignee:
NIKON CORPORATION
International Classes:
G01D5/249; G01D5/244; G01D5/245; H03M1/06; H03M1/24; H03M13/00; (IPC1-7): H03M1/24; G01D5/249; H03M1/06; H03M13/00
Domestic Patent References:
| JP4131713A |