High density stacker crane storage system

Abstract From the Canadian patent

Abstract of the Disclosure, A stacker crane storage and retrieval system comprises a storage rack comprising a plurality of positions defined by vertically and horizontally addressed storage areas, a stacker crane, and a track extending horizontally along the rack on which the stacker crane is adapted to be moved. A table is mounted for vertical movement on a vertical track on the stacker. A sensing scale extends along each track. Each scale includes a Gray code array including alternately dark and light increments, each increment defining a bit. An optical source provided on the crane and the table respectively, includes a source of radiant energy adapted to direct radiant energy against …