Patent ID: 7328983

Claim:
An ink-jet printer, comprising: an ink-jet recording head having (a) an ink inflow passage including an ink inlet into which an ink inflows, and (b) an air-discharge passage which allows the ink inflow passage to communicate with an atmosphere; an air-discharge valve which selectively opens and closes the air-discharge passage; an ink tank which stores the ink and which has (c) an ink outlet from which the ink outflows and (d) an air inlet into which an air inflows; a first connector having an ink supply passage which communicates, at one end thereof, with the ink outlet of the ink tank and communicates, at an other end thereof, with the ink inlet of the ink-jet recording head; an air supplying device which supplies the air to the ink tank via the air inlet thereof; an obtaining portion which obtains one of (e) an elapsed time, t, from a reference time and (f) a volume, V, of an air present in the ink supply passage and the ink inflow passage at the elapsed time t, based on an other of the elapsed time t and the volume V of the air, and a following relationship: V=a·e bt where a and b are coefficients, and e is a base of a natural logarithm; and a control portion which controls, based on the obtained one of the elapsed time t and the volume V of the air, an operation of at least one of the air supplying device and the air-discharge valve.