Patent ID: 6840595

Claim:
An ink jet recording apparatus comprising: a pressure chamber for storing ink; a nozzle fluidly coupled with the pressure chamber for discharging the ink from the pressure chamber; an actuator for increasing and reducing the capacity of the pressure chamber in response to driving signals and continuously discharging a plurality of ink drops through the nozzle for gradational printing to form a single pixel on a recording medium; and a driving signal generator for successively generating, an expansion pulse for increasing the capacity of the pressure chamber and reducing the increased capacity, and a contraction pulse for reducing the capacity of the pressure chamber after a latency subsequent to the expansion pulse and increasing the reduced capacity with a timing such that a time lag between the respective, centers of the expansion pulse and the contraction pulse substantially corresponds to the resonance period of a meniscus generated in the nozzle by the ink in the pressure chamber to prevent involution of air bubbles from appearing in the ink.