Patent ID: 8770689

Claim:
An image forming apparatus comprising: a recording head to eject droplets of a liquid; a head tank mounted on the recording head to supply the liquid to the recording head; a main tank removably mounted in the image forming apparatus to store the liquid to be supplied to the recording head; a liquid supply passage connecting the main tank to the head tank to supply the liquid from the main tank to the head tank; a liquid feed device to feed the liquid from the main tank to the head tank and in reverse from the head tank to the main tank; a measurement unit to measure a consumption amount of the liquid discharged from the recording head; and a supply controller to drive the liquid feed device to control a liquid supply operation on the head tank, wherein the head tank includes a tank housing, a liquid storage portion disposed in the tank housing to store the liquid, a liquid level detection member to detect a liquid level of the liquid in the liquid storage portion, a liquid supply port member connected to the liquid feed device via the liquid supply passage, the liquid supply port member having an opening at a position lower than the liquid level detection member in the liquid storage portion, and an air release unit to open and close an interior of the liquid storage portion relative to an atmosphere, and wherein, when the liquid feed device feeds the liquid from the main tank to the head tank with the interior of the liquid storage portion opened relative to the atmosphere by the air release unit and the liquid level detection member does not detect the liquid level of the liquid after an elapse of a threshold time, the supply controller controls the air release unit to close the interior of the liquid storage portion relative to the atmosphere and determines whether or not a measurement value of the consumption amount of the liquid measured by the measurement unit is a first threshold value or lower, and when the measurement value is the first threshold value or lower, the supply controller performs a reverse feed control to drive the liquid feed device to feed the liquid in reverse from the head tank to the main tank.