Joint for coordinate measurement device

Abstract

An articulating joint for a coordinate measurement machine can include an improved optical encoder. The optical encoder can have an encoder hub and a read head that are rotatable with respect to each other based on movement of the articulating joint about an axis of rotation of the joint. The encoder hub has a read surface. The read surface can be an outer surface of a generally cylindrical segment. The read head can be positioned such that a read direction defined by the read surface is generally perpendicular to the axis of rotation of the articulating joint.

1 . An optical encoder comprising
 a housing;   a shaft rotationally coupled to the housing and defining an axis of rotation, the shaft comprising a read surface directly on the shaft;   a read head rotationally fixed with respect to the housing;   wherein a read direction defined by the position of the read head with respect to the read surface is transverse to the axis of rotation of the shaft.   
   
   
       2 . The optical encoder of  claim 1 , wherein the read direction is substantially perpendicular to the axis of rotation of the shaft. 
   
   
       3 . The optical encoder of  claim 1 , further comprising optical demarcations defining the read surface. 
   
   
       4 . The optical encoder of  claim 1 , further comprising an encoder hub disposed on the shaft, the encoder hub defining the read surface. 
   
   
       5 . The optical encoder of  claim 4 , further comprising optical demarcations on the encoder hub. 
   
   
       6 . The optical encoder of  claim 1 , wherein the read surface comprises a magnetic pattern. 
   
   
       7 . An optical encoder comprising:
 a housing;   a shaft rotationally coupled to the housing and defining an axis of rotation and comprising a tapered receiving portion;   a read surface comprising a tapered mounting portion with which the read surface mounts the tapered receiving portion;   a read head rotationally fixed with respect to the housing;   wherein a read direction defined by the position of the read head with respect to the read surface is transverse to the axis of rotation of the shaft.   
   
   
       8 . The optical encoder of  claim 7 , wherein the read direction is substantially perpendicular to the axis of rotation of the shaft. 
   
   
       9 . The optical encoder of  claim 7 , further comprising optical demarcations defining the read surface. 
   
   
       10 . The optical encoder of  claim 7 , further comprising an encoder hub disposed on the shaft, the encoder hub defining the read surface. 
   
   
       11 . The optical encoder of  claim 10 , further comprising optical demarcations on the encoder hub. 
   
   
       12 . The optical encoder of  claim 7 , wherein the read surface comprises a magnetic pattern. 
   
   
       13 . An optical encoder comprising:
 a housing;   a hollow shaft rotationally coupled to the housing and defining an axis of rotation and comprising a tapered receiving portion;   a read surface rotationally fixed with respect to the shaft;   a read head rotationally fixed with respect to the housing;   wherein a read direction defined by the position of the read head with respect to the read surface is transverse to the axis of rotation of the shaft.   
   
   
       14 . The optical encoder of  claim 13 , further comprising a processor within the hollow shaft and in communication with the read head. 
   
   
       15 . The optical encoder of  claim 13 , wherein the read direction is substantially perpendicular to the axis of rotation of the shaft. 
   
   
       16 . The optical encoder of  claim 13 , further comprising optical demarcations defining the read surface. 
   
   
       17 . The optical encoder of  claim 13 , further comprising an encoder hub disposed on the shaft, the encoder hub defining the read surface. 
   
   
       18 . The optical encoder of  claim 17 , further comprising optical demarcations on the encoder hub. 
   
   
       19 . The optical encoder of  claim 13 , wherein the read surface comprises a magnetic pattern.