Position measuring system
AssigneeDr. Johannes Heidenhain GmbH
InventorJan Braasch
Life of this patent
Estimating the term…
Abstract
A position measuring system for increasing operational dependability, wherein the absolute position is generated by scanning a chain code and erroneously scanned code words are detected and excluded from further processing. A plurality of codes are scanned at areas of the code track which are distanced from each other and are supplied to an error check device.
Claims34
A position measuring system for determining the absolute position of a scanning unit which can be displaced relative to a measurement representation in a measuring direction comprising:
- a measurement representation having a code track with code elements following each other in the measuring direction and forming a sequence of different code words;
- a scanning unit having a plurality of detector elements following each other in the measuring direction for simultaneously scanning several complete, non-overlapping code words;
- and
- an error check device receiving said code words or decoded code words and checking said code words or decoded code words for errors, whereby a correct code word is recognized from several simultaneously detected code words and is used to determine the instantaneous absolute position, and whereby code words recognized as being erroneous are excluded from further processing.
A method of determining the absolute position of a second object displaceable relative to a first object in a measuring direction, the method comprising the steps of:
- providing a measurement representation disposed on the first object having a code track formed by code elements following each other in the measuring direction wherein a sequence of different code words is formed by the code elements;
- simultaneously scanning several code words having predetermined set distances from each other using a scanning unit disposed on the second object, the scanning unit having a plurality of detector elements following each other in the measuring direction and generating at least two code word signals;
- and
- evaluating said code word signals for errors;
- excluding code word signals evaluated as having errors from further processing;
- and
- using code word signals evaluated as not having errors to determine the absolute position of the second object.
A method of determining the absolute position of a second object displaceable relative to a first object in a measuring direction, the method comprising the steps of:
- scanning a measurement representation disposed on the first object with a scanning unit disposed on the second object wherein the measurement representation has a code track formed by code elements sequentially arranged in the measuring direction wherein different code words having predetermined set distances from each other are formed by groups of code elements wherein at least two code words are simultaneously scanned by the scanning unit;
- generating at least two code word signals from the scanned at least two code words;
- evaluating the code word signals for errors;
- excluding code word signals evaluated as having errors;
- and
- using code word signals evaluated as not having errors to determine the absolute position of the second object.
Dependencies are inferred from the claim text.