Patent ID: 8523336

Claim:
An ink supply apparatus, which supplies ink to a recording head having a nozzle, an ink supply opening and ink recovery opening, comprising: a pump including an intake port and a discharge port; a first tank including a first inflow port connected to the discharge port of the pump and a first outflow port connected to the ink supply opening of the recording head; a second tank including a second inflow port connected to the ink recovery opening of the recording head and a second outflow port connected to the intake port of the pump; a third tank, including an ink storage part open to air, which is supplied with ink from an ink supply source; a first relay pipe connected between the first tank and the third tank; a first pressure adjusting mechanism, arranged at the first relay pipe, which is configured to open if the pressure in the first tank is greater than a first given value to discharge ink in the first tank to the third tank; a second relay pipe which connects the ink storage part of the third tank and the second tank; and a second pressure adjusting mechanism, arranged at the second relay pipe, which is configured to open if the pressure in the third tank is lower than a second given value smaller than the first given value to draw ink in the third tank into the second tank.