Patent ID: 8007095

Claim:
A system for reading a coded marker of an ink stick, the system comprising: an optical source located in a feed channel of an ink loader, the optical source being configured to direct a beam of light onto a coded marker formed in an exterior surface of a body of an ink stick as the ink stick passes the optical source in the feed channel, the coded marker having textured areas that are configured to reflect light at a first signal level and non-textured areas that are configured to reflect light at a second signal level, the textured areas and non-textured areas of the coded marker being serially arranged in the exterior surface of the ink stick body; an optical sensor configured to detect light having the first signal strength reflected from the textured areas of the coded marker, to detect light having the second signal strength reflected from the non-textured areas of the coded marker, and to generate signals that correspond to the detected light having the first signal strength and the detected light having the second signal strength; an opaque wall configured to increase a contrast of a detected signal strength of light reflected from the coded marker, the optical source being further configured to focus a beam of light at a point that is directly below the optical sensor and adjacent one end of the opaque wall to shade the optical sensor from the beam of light when the optical sensor is above one of the textured areas of the coded marker; and a controller configured to receive the signals generated by the optical sensor and to process the received signals to identify a code word encoded into the coded marker of the ink stick.