Patent ID: 8870317

Claim:
An image forming apparatus comprising: an apparatus body; a recording head to eject liquid droplets; a head tank to store liquid to be supplied to the recording head; a carriage mounting the recording head and the head tank; a main tank to store the liquid to be supplied to the head tank; a liquid feed device to supply the liquid from the main tank to the head tank; a supply controller to control driving of the liquid feed device to supply the liquid from the main tank to the head tank; a displacement member provided at the head tank and displaceable with a remaining amount of the liquid in the head tank; a first detector mounted on the carriage to detect a first position of the displacement member; and a second detector mounted on the apparatus body to detect a second position of the displacement member, wherein the supply controller detects and retains a differential supply amount corresponding to a displacement amount of the displacement member between the first position and the second position, when the first position of the displacement member is detected with the first detector, the remaining amount of the liquid in the head tank is smaller than when the second position of the displacement member is detected with the second detector, after the printing operation is performed, the supply controller determines whether the displacement member is at a position at which the remaining amount of the liquid in the head tank is smaller than when the displacement member is at the first position, and if the supply controller determines that the displacement member is at the position at which the remaining amount of the liquid in the head tank is smaller than when the displacement member is at the first position, the supply controller controls the liquid feed device to supply the liquid until the first detector detects that the displacement member is at the first position, and after the first detector detects that the displacement member is at the first position, the supply controller controls the liquid feed device to supply the liquid by the differential supply amount from the main tank to the head tank and then the supply controller controls the liquid feed device to stop supply of the liquid.