Patent ID: 8020983
Filing Date: 2011-09-20
Classification: B41J

Abstract:
1. An image forming apparatus comprising: a recording head including one or more nozzles to discharge liquid droplets; a main tank that accommodates liquid to be supplied to the recording head; a sub tank that temporarily accommodates liquid received from the main tank via a liquid supply path and supplies the received liquid to the recording head; a filter integrally attaching the sub tank and the recording head; an air bubble detection unit that detects air bubbles that have penetrated into the liquid supply path; a liquid level detection unit that detects a liquid level within the sub tank, the liquid level detection unit including detection electrodes disposed within the sub tank for detecting whether liquid is contacting tips of the detection electrodes in the sub tank; an exhaust unit that discharges air accommodated within the sub tank, the exhaust unit being configured to release air accumulated within the sub tank to outside atmosphere; a liquid transfer unit including a rotary pump that rotates in one of two opposite directions to transfer liquid from the main tank to the sub tank via the liquid supply path and that rotates in the other of the two opposite directions to retransfer liquid from the sub tank to the main tank via the liquid supply path; and a control unit that is configured to activate the exhaust unit and the liquid transfer unit according to an air bubble detection result of the air bubble detection unit, control the liquid transfer unit to transfer a predetermined amount of liquid from the main tank to the sub tank via the liquid supply path and retransfer liquid from the sub tank to the main tank until the detection electrodes of the liquid level detection unit detect that the liquid is not contacting the tips of the detection electrodes, while controlling the exhaust unit to release air within the sub tank to the outside atmosphere, and control the liquid transfer unit to retransfer liquid from the sub tank to the main tank according to a liquid level detection result of the liquid level detection unit.