Patent ID: 8777374
Filing Date: 2014-07-15
Classification: B41J

Abstract:
1. An image forming apparatus comprising: a main carriage to move and scan in a main scanning direction, the main carriage including at least one recording head mounted thereon; a sub-carriage connectable to the main carriage to move and scan in the main scanning direction together with the main carriage, the sub-carriage including one or more recording heads mounted thereon, wherein the main carriage including the at least one recording head mounted thereon and the sub-carriage including the one or more recording heads mounted thereon are connected to each other; a positioning guide provided on one of the main carriage and the sub-carriage; a position detector provided on the other one of the main carriage and sub-carriage, wherein the position detector reads the positioning guide as the main carriage and the sub-carriage are connected to, or disconnected from, each other to detect relative positions of the main carriage and the sub-carriage in states in which the main carriage and the sub-carriage are connected to, or disconnected from, each other, respectively; and a control unit connected to the position detector to control the main carriage and the sub-carriage based on data from the position detector indicating the relative positions of the main carriage and the sub-carriage, and to control liquid droplet ejection by the recording head on the main carriage and liquid droplet ejection by said one or more recording heads, wherein the control unit determines whether the relative position detected by the position detector is shifted from a reference position in a connected state of the main carriage and the sub-carriage, and when the relative position is shifted from the reference relative position, the control unit determines an amount of the shift, and wherein the control unit corrects timing to discharge liquid droplets from said recording head on the main carriage or from said one or more recording heads on the sub-carriage, based on the amount of the shift when the relative position is shifted from the reference relative position.