Patent ID: 7137691

Claim:
An ink stick for use in a solid ink feed system of a phase change ink jet printer, wherein the ink feed system comprises a feed channel having a feed direction and an insertion opening permitting insertion of an ink stick in an insertion direction, different from the feed direction, into the feed channel, the ink stick comprising: an ink stick body adapted to be inserted in the insertion direction into the feed channel, the ink stick body having an ink stick insertion perimeter in a plane substantially perpendicular to the insertion direction; wherein the ink stick insertion perimeter includes two substantially parallel lateral perimeter segments; wherein the ink stick insertion perimeter includes at least one end perimeter segment; wherein the end perimeter segment is oriented at an angle with respect to the lateral perimeter segments; wherein the end perimeter segment forms a leading portion of the ink stick as the ink stick moves in the feed direction along the feed channel; wherein the ink stick insertion perimeter includes at least three nonlinear key elements; wherein a first of the nonlinear key elements is on a first one of the lateral perimeter segments of the ink stick insertion perimeter; wherein a second of the nonlinear key elements is on a second one of the lateral perimeter segments of the ink stick insertion perimeter; wherein a third of the nonlinear key elements is on the end perimeter segment of the ink stick insertion perimeter; and wherein the third nonlinear key element has a shape substantially identical to the shape of a portion of the insertion opening.