FIG. 4 is a perspective view accompanied with a schematic diagram, showing a system for checking connection between a connector receiver of a first pipe for yellow from an ink tank unit and a connector of a second pipe for yellow from an ink supply device;
FIG. 5A shows a cross-reference table showing correspondence between a light emitter of each color in the ink tank unit and a light receiver of each color in the ink supply device;
FIG. 5B shows another example of the cross-reference table;
FIG. 6 is a flowchart showing an operation performed by the control device of the image forming apparatus according to the first embodiment;
FIG. 7 is a schematic drawing showing an example of an operation device;
FIG. 8A is a schematic drawing showing a decision result indicating normal connection, presented by a decider;
FIG. 8B is a schematic drawing showing an example of a screen displaying the decision result indicating normal connection;
FIG. 8C is a schematic drawing showing another example of the decision result indicating normal connection;
FIG. 9A is a schematic drawing showing a decision result indicating wrong connection, presented by the decider;
FIG. 9B is a schematic drawing showing an example of a screen displaying the decision result indicating wrong connection;
