Patent ID: 6929341

Claim:
An ink jet recording apparatus comprising a main-tank for storing ink, a sub-tank for directly supplying ink to a recording head for carrying out the printing operation to a recording medium by ejecting ink, ink supply means for suppling a predetermined amount of ink from said main-tank to said sub-tank, and ink discharge means for discharging ink in said sub-tank, wherein in the following equation: A /( A−a×B ) =R ≦1.20 the maximum amount of ink capable of being stored in said sub-tank is represented by A, an amount of residual ink remaining in said sub-tank after the ink has been discharged by said ink discharge means is represented by “a”, a ratio by weight of a volatile component in the ink used is represented by B, and a ratio of a colorant concentration of the ink at a saturated state by repeating the ink supply and the ink discharge to an initial colorant concentration of the ink is represented by R, and wherein the A, the “a” and the B are set so as to satisfy the above equation.