Patent ID: 8226188

Claim:
An image former comprising: an ink discharge unit including a plurality of nozzles and corresponding ink propelling mechanisms for the nozzles, and configured to discharge ink through the nozzles in accordance with drive signals to drive the ink propelling mechanisms; an ink temperature sensor adapted to measure a temperature of ink at the ink discharge unit; and a negative-pressure controller configured to control negative pressures acting on menisci formed in vicinities of the nozzles by surface tension of ink at the ink discharge unit, wherein the negative-pressure controller is configured to work with a discharge of ink by the ink discharge unit, operating for a measured temperature of ink by the ink temperature sensor equal to or higher than a first reference, to control the negative pressures to a first value, and for a measured temperature of ink by the ink temperature sensor lower than the first reference, to control the negative pressures to a second value which is lower than the first value.