| 摘要 |
PURPOSE:To widen the range of gradation by changing the time lag of the generation of a driving pulse behind the generation of a timing pulse which is synchronous to the movement of a carriage. CONSTITUTION:With a time lag of T1 behind the leading edge of the timing pulse 22 generated synchronously with the movement of the carriage, the driving pulse 21 for jetting the ink is impressed on a piezoelectric element, and with a further time lag of T2 corresponding to gradation data, the driving pulse 20 is impressed on the piezoelectric element. The driving pulse 20 is always impressed earlier than the driving pulse 21, and the time lag T2 between the two driving pulses is set to be longer for a lighter gradation, i.e., a smaller volume of the ink droplet jetted. When the pulse 20 is impressed, since the increase in the pressure in the pressure chamber is slow, the ink tending to be jetted can not overcome the surface tension and it is retracted into a nozzle after forming a meniscus which is convexed to the outside of the nozzle. |
